Integrated linear generator system

Abstract

To provide an excellent integrated linear generator system.SOLUTION: An integrated linear generator system includes, for example, a generator assembly, a control system, a frame system, an exhaust system, an intake system, a cooling system, a bearing system, one or more auxiliary systems, or a combination thereof. The generator system is configured to generate power, as controlled by the control system. The generator assembly may include an opposed- and free-piston linear generator configured to operate on a two-stroke cycle. The intake and exhaust systems are configured to provide reactants for and remove products from the generator assembly, respectively. The cooling system is configured to effect heat transfer, material temperature, or both, of components of the integrated linear generator system.SELECTED DRAWING: Figure 55

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This disclosure relates to an integrated linear generator system and aspects thereof. This application claims the benefit of U.S. Provisional Patent Application No. 62 / 781,586, filed December 18, 2018, the entire disclosure of which is incorporated herein by reference. [Background technology]

[0002] Power generation systems typically rely on various subsystems working in concert. For example, a typical crankshaft engine includes a rotating assembly including pistons, connecting rods, oiled bearings, and a crankshaft, an oil system, a cooling system, an ignition system, a valve system and camshaft, a fuel system, and an exhaust system. These subsystems are tailored to the crankshaft engine. Summary of the Invention [Means for solving the problem]

[0003] In some embodiments, the present disclosure relates to a linear generator. The linear generator includes a structural frame, a cylinder, a first linear electromagnetic machine (LEM), and a second LEM. The cylinder is attached to a central region of the structural frame. The LEM is disposed on a first longitudinal side of the cylinder and is attached to the structural frame. The second LEM is disposed on a second longitudinal side of the cylinder and is attached to the structural frame. The second longitudinal side is opposite the first longitudinal side. The second LEM is aligned with the first LEM, and the cylinder is aligned with the first and second LEM. For example, in some embodiments, the first LEM is aligned laterally or axially with respect to the second LEM, or both. In some embodiments, the first LEM includes a first stator bore, the second LEM includes a second stator bore, and the first stator bore is aligned with the second stator bore. In some embodiments, the cylinder is attached to the structural frame by one or more flexures, e.g., in some embodiments, the one or more flexures are relatively stiffer to lateral displacement than to axial displacement.

[0004] In some embodiments, the linear generator includes a first gas spring cylinder attached to the structural frame and aligned with a first LEM, and a second gas spring cylinder attached to the structural frame and aligned with a second LEM.

[0005] In some embodiments, the structural frame includes one or more openings in a top surface that allow for insertion of a cylinder into the structural frame, that allow for insertion of a first LEM into the structural frame, and that allow for insertion of a second LEM into the structural frame.

[0006] In some embodiments, the linear generator includes at least one mount attached to the frame, the linear generator being capable of operating in one or more frequency ranges, and the mount being capable of damping vibrations from the linear generator.

[0007] In some embodiments, the structural frame includes one or more end members that allow for axial thermal expansion and maintain lateral rigidity.

[0008] In some embodiments, the present disclosure relates to a linear generator including a structural frame, a cylinder, a first stator, and a second stator. The cylinder is mounted in a central region of the structural frame, the first stator is disposed on a first longitudinal side of the cylinder and is mounted to the structural frame, and the second stator is disposed on a second longitudinal side of the cylinder and is mounted to the structural frame. The second longitudinal side is opposite the first side, and the second stator is aligned with the first stator, and the cylinder is aligned with the first and second stators.

[0009] In some embodiments, the linear generator includes a first translator arranged to interact with both the first stator and the cylinder, and a second translator arranged to interact with both the second stator and the cylinder. In some embodiments, the linear generator includes one or more first gas bearing housings that constrain the first translator relative to the first stator, and one or more second gas bearing housings that constrain the second translator relative to the second stator. In some embodiments, each translator includes a first piston arranged to move along the axis of the cylinder and a magnet section that interacts with the respective stator. For example, the piston on the opposite side of the translator defines a reaction section of the cylinder.

[0010] In some embodiments, the structural frame includes one or more end members that allow for axial thermal expansion and maintain lateral stiffness.

[0011] In some embodiments, the present disclosure relates to a structural frame for mounting components of a linear generator. The structural frame includes one or more members for providing axial and lateral stiffness, a first mounting region of the one or more members for receiving a first LEM, a second mounting region of the one or more members for receiving a second LEM, a third mounting region of the one or more members for receiving a cylinder, and one or more openings between the one or more members. The one or more openings correspond to the first mounting region, the second mounting region, and the third mounting region.

[0012] In some embodiments, the one or more openings are disposed in the top surface of the structural frame such that the first mounting area receives a first LEM through the top surface, the second mounting area receives a second LEM through the top surface, and the third mounting area receives a cylinder through the top surface.

[0013] In some embodiments, the structural frame includes one or more end members coupled to one or more members. The one or more end members allow for axial thermal expansion while maintaining lateral stiffness. In some embodiments, the first mounting region, the second mounting region, and the third mounting region are aligned axially and laterally.

[0014] In some embodiments, the present disclosure relates to a linear generator including an intake system configured to supply intake gas to a reaction section.

[0015] In some embodiments, the present disclosure relates to a linear generator including an exhaust system configured to remove exhaust gases from a reaction section.

[0016] In some embodiments, the present disclosure relates to a linear generator including a fuel system configured to supply fuel to a mixture with intake air upstream of or in a reaction section.

[0017] In some embodiments, the present disclosure relates to a linear generator that includes an electrical system configured to manage electrical interactions such as power management, control signals, sensor circuits, control circuits, and other circuits.

[0018] In some embodiments, the present disclosure relates to a linear generator including a control system configured to communicate with sensors, receive sensor signals, generate control signals, determine operating parameters, execute computer instructions, and otherwise control aspects of the operation and characterization of the linear generator.

[0019] In some embodiments, the present disclosure relates to a system including one or more cores, for example, each core can include a linear generator or generator assembly.

[0020] In some embodiments, the present disclosure relates to a linear generator including a cooling system configured to manage heat flow and temperature of the linear generator.

[0021] In some embodiments, the present disclosure relates to a linear generator including a bearing system configured to manage the stiffness and operation of a bearing, for example, a gas bearing (e.g., gas bearing pressure, flow rate, or both). The present invention provides, for example, the following. (Item 1) A structural frame; a cylinder attached to a central region of the structural frame; a first linear electromagnetic machine (LEM) disposed on a first longitudinal side of the cylinder and attached to the structural frame; a second LEM disposed on a second longitudinal side of the cylinder and attached to the structural frame, the second longitudinal side being opposite the first longitudinal side, the second LEM being aligned with the first LEM, and the cylinder being aligned with the first LEM and the second LEM. Linear generator. (Item 2) a first gas spring cylinder attached to the structural frame and aligned with the first LEM; a second gas spring cylinder attached to the structural frame and aligned with the second LEM; Item 1. The linear generator according to item 1, further comprising: (Item 3) The structural frame is Inserting the cylinder into the structural frame; Inserting the first LEM into the structural frame; Inserting the second LEM into the structural frame; and Item 1. The linear generator according to item 1, comprising one or more openings in the top surface that allow (Item 4) the first LEM includes a first stator bore; the second LEM includes a second stator bore, and the first stator bore is aligned with the second stator bore; Item 1. A linear generator according to item 1. (Item 5) Item 1. The linear generator according to item 1, wherein the cylinder is attached to the structural frame by one or more flexures. (Item 6) Item 6. A linear generator according to item 5, wherein the one or more flexures are relatively stiffer to lateral displacement than to axial displacement. (Item 7) Item 1. The linear generator of item 1, wherein the first LEM is aligned laterally relative to the second LEM. (Item 8) Item 1. The linear generator of item 1, wherein the first LEM is axially aligned with respect to the second LEM. (Item 9) further comprising at least one mount attached to the frame; the linear generator operates in one or more frequency ranges; the mount is capable of damping vibrations from the linear generator; Item 1. A linear generator according to item 1. (Item 10) Item 1. The linear generator of item 1, wherein the structural frame includes one or more end members, the one or more end members allowing for axial thermal expansion, and the one or more end members maintaining lateral stiffness. (Item 11) A structural frame; a cylinder attached to a central region of the structural frame; a first stator disposed on a first longitudinal side of the cylinder and attached to the structural frame; a second stator disposed on a second longitudinal side of the cylinder and attached to the structural frame, the second longitudinal side being opposite the first side, the second stator being aligned with the first stator, and the cylinder being aligned with the first stator and the second stator. Linear generator. (Item 12) a first translator arranged to interact with the first stator and the cylinder; and a second translator arranged to interact with the second stator and the cylinder. Item 12. The linear generator according to item 11, further comprising: (Item 13) one or more first gas bearing housings that constrain the first translator relative to the first stator; one or more second gas bearing housings that constrain the second translator relative to the second stator; and Item 13. The linear generator according to item 12, further comprising: (Item 14) The first translator: a first piston disposed for movement along the axis of the cylinder; a first magnet section interacting with the first stator; and Including, The second translator: a second piston disposed to move along the axis of the cylinder; a second magnet section interacting with the second stator; and Including, Item 13. The linear generator according to item 12. (Item 15) Item 15. The linear generator of item 14, wherein the first piston and the second piston define a reaction section of the cylinder. (Item 16) Item 12. The linear generator of item 11, wherein the structural frame includes one or more end members, the one or more end members allowing for axial thermal expansion, and the one or more end members maintaining lateral stiffness. (Item 17) 1. A structural frame for mounting components of a linear generator, comprising: one or more members for providing axial and lateral stiffness; a first mounting area of ​​the one or more members for receiving a first linear electromagnetic machine (LEM); a second mounting area of ​​the one or more members for receiving a second LEM; a third mounting region of the one or more members for receiving a cylinder; and one or more openings in the one or more members corresponding to the first mounting region, the second mounting region, and the third mounting region. Including, structural frame. (Item 18) the one or more openings are located on a top surface of the structural frame; the first mounting area receives the first LEM through the top surface; the second mounting area receives the second LEM through the top surface; The third mounting area receives the cylinder through the top surface. Item 18. The structural frame according to item 17, (Item 19) Item 18. The structural frame of item 17, further comprising one or more end members coupled to the one or more members, the one or more end members allowing for axial thermal expansion and the one or more end members maintaining lateral stiffness. (Item 20) Item 18. The structural frame of item 17, wherein the first mounting region, the second mounting region, and the third mounting region are axially and laterally aligned.

[0022] The present disclosure, in accordance with one or more various embodiments, will be described in detail with reference to the following figures. The drawings are provided for illustrative purposes only and merely represent typical or example embodiments. These drawings are provided to facilitate understanding of the concepts disclosed herein and should not be considered as limiting the breadth, scope, or applicability of these concepts. It should be noted that for clarity and ease of illustration, these drawings have not necessarily been made to scale. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 illustrates a system diagram of an exemplary integrated linear generator system, according to some embodiments of the present disclosure. [Figure 2] FIG. 2 illustrates a cross-sectional side view of an exemplary generator assembly according to some embodiments of the present disclosure. [Figure 3]FIG. 3 is a block diagram of an exemplary linear generator including a control system for controlling operation of the generator assembly, according to some embodiments of the present disclosure. [Figure 4] FIG. 4 illustrates a portion of an exemplary generator assembly with a reaction section piston at various respective axial positions according to some embodiments of the present disclosure. [Figure 5] FIG. 5 illustrates a portion of an exemplary generator assembly with lean fronting, according to some embodiments of the present disclosure. [Figure 6] FIG. 6 shows two cross-sectional views of an exemplary translator having a reservoir, according to some embodiments of the present disclosure. [Figure 7] FIG. 7 illustrates a system diagram of an exemplary air intake system, according to some embodiments of the present disclosure. [Figure 8] FIG. 8 shows a side view of an exemplary breathing port in a cylinder, according to some embodiments of the present disclosure. [Figure 9] FIG. 9 illustrates a cross-sectional end view of the exemplary cylinder of FIG. 8, according to some embodiments of the present disclosure. [Figure 10] FIG. 10 shows a side view of an exemplary breathing port in a cylinder sized and positioned to reduce ring stress, according to some embodiments of the present disclosure. [Figure 11] FIG. 11 shows a cross-sectional end view of an exemplary shape of a breathing port in a cylinder, according to some embodiments of the present disclosure. [Figure 12] FIG. 12 shows a cross-sectional end view of an exemplary shape of a breathing port in a cylinder, according to some embodiments of the present disclosure. [Figure 13] FIG. 13 illustrates a cross-sectional view of an example integrated linear generator system portion configured for premixed air and fuel, according to some embodiments of the present disclosure. [Figure 14] FIG. 14 illustrates a cross-sectional view of an exemplary integrated linear generator system portion configured for in-port injection, according to some embodiments of the present disclosure. [Figure 15]FIG. 15 illustrates a cross-sectional view of an exemplary integrated linear generator system portion configured for injection, according to some embodiments of the present disclosure. [Figure 16] FIG. 16 illustrates a cross-sectional side view of an exemplary intake portion of a linear generator, according to some embodiments of the present disclosure. [Figure 17] FIG. 17 illustrates a cross-sectional side view of an exemplary intake portion of a linear generator, according to some embodiments of the present disclosure. [Figure 18] FIG. 18 illustrates a system diagram of an exemplary fuel system, according to some embodiments of the present disclosure. [Figure 19] FIG. 19 shows a system diagram of an exemplary exhaust system according to some embodiments of the present disclosure. [Figure 20] FIG. 20 illustrates a cross-sectional view of an exemplary integrated linear generator system portion configured for exhaust gases, according to some embodiments of the present disclosure. [Figure 21] FIG. 21 illustrates a cross-sectional view of an exemplary exhaust manifold according to some embodiments of the present disclosure. [Figure 22] FIG. 22 shows a cross-sectional view of an exemplary gas spring system according to some embodiments of the present disclosure. [Figure 23] FIG. 23 shows a cross-sectional side view of an exemplary gas spring system having a reservoir, according to some embodiments of the present disclosure. [Figure 24] FIG. 24 illustrates a cross-sectional side view of the exemplary gas spring system of FIG. 23 with the translator in a second position, according to some embodiments of the present disclosure. [Figure 25] FIG. 25 illustrates a cross-sectional side view of an exemplary gas spring system having a reservoir configured for intake compression, according to some embodiments of the present disclosure. [Figure 26] FIG. 26 shows a side cross-sectional view of a portion of an exemplary gas spring system having a reservoir, according to some embodiments of the present disclosure. [Figure 27] FIG. 27 shows a side cross-sectional view of a portion of an exemplary gas spring system having a reservoir, according to some embodiments of the present disclosure. [Figure 28] FIG. 28 shows a side cross-sectional view of a portion of an exemplary gas spring system having a reservoir, according to some embodiments of the present disclosure. [Figure 29] FIG. 29 shows several perspective views of an exemplary gas spring system, according to some embodiments of the present disclosure. [Figure 30] FIG. 30 shows a side cross-sectional view of an exemplary gas spring cylinder assembly, according to some embodiments of the present disclosure. [Figure 31] FIG. 31 illustrates a side cross-sectional view of the exemplary gas spring cylinder assembly of FIG. 30 opened using a sliding bushing, according to some embodiments of the present disclosure. [Figure 32] FIG. 32 shows a system diagram of an exemplary bearing system, according to some embodiments of the present disclosure. [Figure 33] FIG. 33 illustrates a cross-sectional view of an exemplary generator assembly portion, according to some embodiments of the present disclosure. [Figure 34] FIG. 34 illustrates a cross-sectional view of an exemplary generator assembly portion, according to some embodiments of the present disclosure. [Figure 35] FIG. 35 illustrates a cross-sectional view of an exemplary generator assembly portion, according to some embodiments of the present disclosure. [Figure 36] FIG. 36 shows an enlarged cross-sectional view of the example generator assembly portion of FIG. 34 with a seal axially positioned in front of the intake port, according to some embodiments of the present disclosure. [Figure 37] FIG. 37 shows an enlarged cross-sectional view of the example generator assembly portion of FIG. 34 with a piston seal axially positioned aft of the intake port, according to some embodiments of the present disclosure. [Figure 38] FIG. 38 shows an enlarged cross-sectional view of an exemplary generator assembly portion, according to some embodiments of the present disclosure. [Figure 39A] FIG. 39A shows a cross-sectional view of an example generator assembly portion with a seal in a ring compressor, according to some embodiments of the present disclosure. [Figure 39B] FIG. 39B shows a cross-sectional view of the example generator assembly portion of FIG. 39A with a seal on the outside of the ring compressor, according to some embodiments of the present disclosure. [Figure 40] FIG. 40 illustrates a cross-sectional view of an exemplary generator assembly portion having an intake seal, according to some embodiments of the present disclosure. [Figure 41] FIG. 41 shows a cross-sectional view of an example generator assembly portion having an intake manifold that seals against a bearing housing, according to some embodiments of the present disclosure. [Figure 42] FIG. 42 shows a side view of an exemplary translator, according to some embodiments of the present disclosure. [Figure 43] FIG. 43 shows an axial end view of the example translator of FIG. 42, according to some embodiments of the present disclosure. [Figure 44] FIG. 44 shows a side cross-sectional view of an exemplary translator having a tapered region and an optional spacer according to some embodiments of the present disclosure. [Figure 45] FIG. 45 shows a side cross-sectional view of an exemplary translator tube end and rail with a cantilever cross-section, according to some embodiments of the present disclosure. [Figure 46] FIG. 46 shows a perspective view of an exemplary translator tube end coupled to a piston via a fastener, according to some embodiments of the present disclosure. [Figure 47] FIG. 47 shows a perspective view of an exemplary translator tube end coupled to a piston via an obliquely oriented fastener, according to some embodiments of the present disclosure. [Figure 48] FIG. 48 shows an end view of an example translator and additional components according to some embodiments of the present disclosure. [Figure 49] FIG. 49 shows a cross-sectional view of an example translator and stator and an enlarged portion according to some embodiments of the present disclosure. [Figure 50]FIG. 50 illustrates a cross-sectional view of an example translator and stator according to some embodiments of the present disclosure. [Figure 51] FIG. 51 shows a cross-sectional view of an exemplary translator and bearing housing, according to some embodiments of the present disclosure. [Figure 52] FIG. 52 shows a system diagram of an exemplary cooling system, according to some embodiments of the present disclosure. [Figure 53] FIG. 53 shows a top view of an exemplary frame system according to some embodiments of the present disclosure. [Figure 54] FIG. 54 shows a side view of an exemplary frame system according to some embodiments of the present disclosure. [Figure 55] FIG. 55 shows a side view of an exemplary assembly including a frame system coupled to a generator assembly, according to some embodiments of the present disclosure. [Figure 56] FIG. 56 shows an end view of an exemplary frame system according to some embodiments of the present disclosure. [Figure 57] FIG. 57 shows a cross-sectional view of a portion of an exemplary integrated linear generator system including an end member, a gas spring cylinder, and a head, according to some embodiments of the present disclosure. [Figure 58] FIG. 58 illustrates a side view of an exemplary assembly including a cylinder with a mount, according to an embodiment of the present disclosure. [Figure 59] FIG. 59 illustrates an exemplary cylinder assembly with an intake manifold having a mount, according to some embodiments of the present disclosure. [Figure 60] FIG. 60 shows a perspective view of an exemplary core according to some embodiments of the present disclosure. [Figure 61] FIG. 61 shows a perspective view of an exemplary system including two cores, according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0024] In some embodiments, the present disclosure provides a linear generator system configured to provide electrical work (i.e., power) from fuel and oxidant inputs. In some embodiments, the present disclosure provides a linear system configured to convert between kinetic energy and electrical energy. In some embodiments, the linear generator includes a pair of opposing vibration translators arranged along an axis. Both translators contact a single compression or reaction section, and each translator also contacts a respective driver section (e.g., a gas spring). As each translator moves along the axis, the compression or reaction section and the gas spring are alternately compressed and expanded. In some embodiments, there is no mechanical linkage between the translators (i.e., a linear free-piston generator or a linear free-translator generator). Electrical work is extracted from the linear generator via a multi-phase stator configured to electromagnetically interact with the translator as it moves.

[0025] 1 shows a system diagram of an exemplary integrated linear generator system 100 according to some embodiments of the present disclosure. The integrated linear generator system 100 includes a generator assembly 102, a control system 104, an electrical system 105, a frame system 106, an exhaust system 108, an air intake system 110, a cooling system 112, a bearing system 114, and auxiliary system(s) 116. The generator system 100 is configured to generate and manage electrical power as controlled by the control system 104 and the electrical system 105. In some embodiments, the electrical system 105 includes both low-voltage and high-voltage components. For example, the electrical system 105 may include 480 VAC components (e.g., grid or grid-connected components, auxiliary components), 120 VAC components / circuits (e.g., auxiliary components), high-voltage DC buses and components (e.g., greater than 400 VDC, greater than 700 VDC, or greater than 1000 VDC components), low-voltage DC buses and components (e.g., 12 VDC, 24 VDC, or 48 VDC components), low-voltage DC components (e.g., 12 VDC, 24 VDC, or 48 VDC components), other suitable electrical circuits operating at any suitable voltage and current characteristics, or any combination thereof. The intake system 110 is configured to provide reactants (e.g., air, fuel, or both) to the generator assembly 102, and the exhaust system 108 is configured to remove exhaust products from the generator assembly 102. The cooling system 112 is configured to limit, control, or otherwise influence heat transfer and material temperatures of the components of the integrated linear generator system 100. The bearing system 114 is configured to constrain off-axis motion (e.g., radial, lateral, or other transverse motion) of the translator of the generator assembly 102 using, for example, low-friction gas bearings. The frame system 106 is configured to manage the stiffness, flexibility, and alignment of the components of the integrated linear generator system 100.The division among, or combination of, systems 102-114 may be implemented in any suitable arrangement and are shown separately in Figure 1 for purposes of the following description. For example, any suitable components of control system 104, electrical system 105, frame system 106, bearing system 114, air intake system 110, exhaust system 108, and cooling system 112 may be integrated into generator assembly 102. Auxiliary system(s) 116 may include any suitable system or subsystem configured to support operation of integrated linear generator system 100.

[0026] It will be understood that system 100 is merely exemplary. Any suitable combination of subsystems may be used, including those that include fewer or more than those shown in FIG. 1.

[0027] The generator assembly 102 includes moving and stationary assemblies and components configured to convert, for example, chemical and / or thermal energy into electrical energy. In some embodiments, the generator assembly 102 includes a cylinder, a translator, a stator, bearings, bearing housings, seals, corresponding alignment hardware, any other suitable components, or any suitable combination thereof. In some embodiments, the generator assembly 102 is configured to run a thermodynamic cycle, such as, for example, a chemical engine cycle. An exemplary example includes a two-stroke piston engine cycle using compression ignition and port breathing via uniflow scavenging (e.g., an intake port at a first axial end and an exhaust port located at a second axial end, with scavenging occurring primarily axially). In further examples, cycle approximations, for example, the generator assembly 102 may be configured to run, for example, an Otto cycle, a Diesel cycle, an Atkinson cycle, a Miller cycle, a Carnot cycle, an Ericsson cycle, a Stirling cycle, or any other suitable idealized or real cycle, or any suitable combination thereof.

[0028] FIG. 2 illustrates a cross-sectional view of an exemplary generator assembly 200 according to some embodiments of the present disclosure. The generator assembly 200 is configured as an opposed generator. The generator assembly 200 includes translators 210 and 220 configured to move along an axis 206 (e.g., linearly translate along the axis 206). The translators 210 and 220 are configured to move within cylinders 202, 204, and 205, thus forming expansion and compression volumes 297, 298, and 299 for performing boundary actions (e.g., determined using the circular integral of PdV over an appropriate range, such as strokes or cycles). For clarity, the spatial arrangements of the systems and assemblies described herein are generally referenced in the context of cylindrical coordinates having axial, radial, and azimuthal directions. It will be understood that any suitable coordinate system can be used according to the present disclosure (e.g., cylindrical coordinates can be mapped to any suitable coordinate system). Note that axis 206 is oriented in an axial direction, and radial directions are defined as being perpendicular to axis 206 (e.g., directed away from axis 206). Azimuthal directions are defined as angular directions about axis 206 (e.g., perpendicular to both axis 206 and the radial direction and directed about axis 206).

[0029] In some embodiments, the fixed mounting components of generator assembly 200 include cylinder 202, cylinder 204, cylinder 205, stator 218, stator 228, bearing housing 216, bearing housing 217, bearing housing 226, bearing housing 227, seal 215, seal 225, exhaust manifold 271, and intake manifold 272. In some embodiments, bearing housings 216 and 217 are coupled to stator 218 (e.g., directly connected or coupled by an intermediate component such as a flexure or mount). For example, bearing housings 216 and 217 may be aligned (e.g., laterally or axially aligned) and fixed to stator 218 to maintain a radial air gap between magnet assembly 213 and stator 218. Similarly, in some embodiments, bearing housings 226 and 227 are rigidly coupled to stator 228.

[0030] Translator 210 includes tube 212, piston 211, seal 262, piston 214, seal 261, and magnet assembly 213, all of which are substantially rigidly coupled to move along axis 206 relative to a mounting component. Translator 220 includes tube 222, piston 221, seal 263, piston 224, seal 264, and magnet assembly 223, all of which are substantially rigidly coupled to move along axis 206. In some embodiments, pistons 211 and 221 can include mechanisms or components (e.g., spacers with low thermal conductivity, collars that affect the flow of blow-by gases, or both) that manage, modify, reduce, or otherwise control the thermal expansion of or heat transfer to tubes 212 and 222, respectively. In some embodiments, magnet assemblies 213 and 223 can be regions of tubes 212 and 222, respectively. In some embodiments, magnet assemblies 213 and 223 may comprise separate components attached to tubes 212 and 222, respectively. Reaction section 297 is bounded not only by bore 203 of cylinder 202 but also by pistons 211 and 221 (e.g., also by seals 262 and 263). Gas springs 298 and 299 are bounded by respective pistons 214 and 224 and respective cylinders 204 and 205. Thus, as translators 210 and 220 move along axis 206, the volumes of reaction section 297, gas spring 298, and gas spring 299 expand and contract. Further, for example, the pressure within those volumes decreases or increases as the volumes increase or decrease, respectively. Each of bearing housings 216, 217, 226, and 227 is configured to provide a gas bearing between itself and the corresponding translator (e.g., tube 212 and 222).For example, each of bearing housings 216, 217, 226, and 227 may be configured to direct pressurized gas to the gas bearings (e.g., via a flow system). In an exemplary embodiment, each of bearing housings 216, 217, 226, and 227 may be configured to direct pressurized gas having an absolute pressure greater than ambient pressure (e.g., 1 atmosphere at sea level) to the gas bearings such that the bearing gas has sufficient pressure to flow through the gas bearings (e.g., directly or via other ducts) to the environment. In some embodiments, the bearing gas may be pressurized relative to the environment (e.g., approximately 1 atmosphere), pressure in a breathing system (e.g., boost pressure or gas pressure in an exhaust system that may be greater or less than 1 atmosphere), or other suitable pressure reference. In some embodiments, generator assembly 200 is configured for oil-less operation with bearing housings 216, 217, 226, and 227 forming gas bearings relative to translators 210 and 220. Each of translators 210 and 220 is configured to achieve a position-velocity trajectory. The trajectory can include a top dead center (TDC) position when each translator is closest to (i.e., more inboard than) the axial centerline 207, and a bottom dead center (BDC) position when each translator is furthest from (i.e., more outboard than) the axial centerline 207.

[0031] Cylinder 202 includes bore 203 that houses reaction section 297. Cylinder 202 also includes exemplary intake breathing port 219 and exhaust breathing port 229, which couple bore 203 to the exterior of cylinder 202. For example, intake breathing port 229 couples bore 203 to an intake system such as its intake manifold 272. In a further example, exhaust breathing port 219 couples bore 203 to an intake system such as its exhaust manifold 271. Intake manifold 272 can be sealed to cylinder 202, to seal 225 (e.g., by extending axially to seal 225), to bearing housing 226 (e.g., by extending axially to bearing housing 226), to an intervening component, or a combination thereof. Exhaust manifold 271 may seal to cylinder 202, to seal 215, to bearing housing 216 (e.g., by extending axially into bearing housing 216), to an intervening component, or a combination thereof. In some embodiments, as shown, seal 215 includes a contact seal, which may be made of a self-lubricating material (e.g., graphite), a ceramic material, a metal, a plastic, or any other suitable material, or any combination thereof. Seal 215 is stationary relative to the movement of translator 210 and may be housed within ring compressor 281 (as shown), cylinder 202, a dedicated seal holder, or other suitable component, or any combination thereof. In some embodiments, seal 215 includes a contact seal, a contactless seal, other suitable seal, or any combination thereof. In some embodiments, as shown, a translator cooler 270 may be included to provide a flow of pressurized gas used to cool translator 210. In some embodiments, cooling gas for translator cooler 270 may be provided by a blower (e.g., in an air intake system), a reservoir in a gas spring system, a port in a gas spring system, an external gas supply, other suitable gas supply, or any combination thereof.In some embodiments, the translator cooler 270 may be configured to provide preferential cooling fluid flow. For example, the translator cooler 270 may provide more cooling fluid flow to one or more surface regions of the translator 210 and less cooling fluid flow to one or more other surface regions of the translator 210, or vice versa. In some embodiments, the translator cooler 270 may be configured to provide substantially uniform cooling. When the intake breathing port 229 is not covered by the piston 221 (e.g., when the intake port is open), fluid exchange may occur between the reaction section 297 and the intake system. When the exhaust breathing port 219 is not covered by the piston 211, fluid exchange may occur between the reaction section 297 and the exhaust system. Fluid flow occurs primarily from the intake system through the intake breathing port 229 to the bore 203, and from the bore 203 through the exhaust breathing port 219 to the exhaust system. For example, averaged over time, fluid flows from the intake system to the bore 203 and from the bore 203 to the exhaust system. However, flow may also occur during periods (e.g., intermittent or transient events) in the opposite direction, such as from blowback or plugging pulses. In some embodiments, the radially outer surface of the cylinder 202 is cooled. For example, the radially outer surface of the cylinder 202 may be air-cooled (e.g., by a cooling system), liquid-cooled (e.g., by a cooling system), or both. In some embodiments, a thermal interface material may be disposed between the air-cooling mechanism (such as fins) and the cylinder 202 to improve thermal conductivity. In some embodiments, the cylinder 202 may include one or more ports disposed between the intake breathing port 229 and the exhaust breathing port 219, which may be configured to accommodate sensors (e.g., coupled to a control system), fuel injectors (e.g., coupled to the intake system or a dedicated fuel system), or other suitable components that may require access to the bore 203.Along axis 206, intake breathing port 229 and exhaust breathing port 219 may, but need not, be symmetrically positioned about the center of cylinder 202. Port locations can be referenced to any suitable datum, with one datum being the location of the port's front face (e.g., nearest axial centerline 207). The port's front face defines a closed portion of the cycle (e.g., start of compression, end of expansion, start of breathing, end of breathing). For example, in some embodiments, exhaust breathing port 219 may be closer to axial centerline 207 than intake breathing port 229. Illustratively, exhaust breathing port 219 can open to reaction section 297 before intake breathing port 229 during the expansion stroke, and exhaust breathing port 219 can close to reaction section 297 after intake breathing port 229 during the compression stroke. In some embodiments, breathing techniques other than uniflow scavenging, such as loop scavenging or cross scavenging, can be used, and thus the breathing ports can be positioned to be opened by only a single piston (e.g., with the intake and exhaust breathing ports on the same axial side of the cylinder). In some embodiments, the centerline of the piston position can be changed during operation to change the relative timing of port opening and closing. For example, the port locations can be fixed spatially on the cylinder 202, but the apex positions (e.g., TDC and BDC positions) of the pistons 211 and 221 can be selected to move the TDC centerline (e.g., the midpoint between the TDC positions of the pistons 211 and 221 in either axial direction). In a further example, moving the TDC centerline can allow for altering the breathing behavior. Correspondingly, the timing of port opening and closing, the relative strength (e.g., pressure wave amplitude), or both of the breathing behavior can be changed. Furthermore, the compression ratio, the expansion ratio, or both can be changed by moving the TDC centerline or the BDC position. To illustrate, the TDC centerline may be, but need not be, axially aligned with the axial centerline 207 .The location of the breathing ports and the piston apex position can be used to affect breathing behavior. In some embodiments, the BDC position of one or both pistons can be changed during operation to change the relative timing of port opening and closing. For example, one port can be left open longer to affect breathing. It will be understood that TDC and BDC refer to the respective positions of the piston in contact with the reaction section (e.g., corresponding to the TDC and BDC of the piston in contact with the gas spring, respectively). For example, at or near TDC, the reaction section has a minimum volume and the gas spring has a maximum volume. As a further example, at or near BDC, the reaction section has a maximum volume and the gas spring has a minimum volume. In some embodiments, the cylinder assembly 254 includes the cylinder 202, the intake manifold 272, the exhaust manifold 271, mounting hardware (e.g., mounts, flexures, or other hardware), and any other suitable components that can be mounted as a unit. Ring compressors 281 and 282 are coupled to the axial ends of cylinder 202 for the purpose of maintaining seals 262 and 263 within pistons 211 and 221, respectively, during replacement, installation, removal, or inspection. For example, during inspection or maintenance, translators 210 and 220 may be axially positioned such that ring compressors 281 and 282 are axially aligned with their respective seals 262 and 263. Additionally, ring compressors 281 and 282 may be removed along with their respective pistons 211 and 221 during maintenance or inspection. Ring compressors 281 and 282 may have the same or similar inner diameter as bore 203 of cylinder 202. In some embodiments, ring compressors 281 and 282 may include two or more sections (e.g., a clamshell design) configured to hold seals 262 and 263 in place during replacement, installation, removal, or inspection.In some embodiments, ring compressors 281 and 282 may comprise a single component configured to retain seals 262 and 263 during replacement, installation, removal, or inspection. Ring compressors 281 and 282 may be attached to cylinder 202 via any suitable means, including, but not limited to, V-band clamps, fasteners, bolts, springs, or any combination thereof.

[0032] In some embodiments, as shown, cylinders 204 and 205 are closed by respective heads 208 and 209, which may be bolted or otherwise secured to cylinders 204 and 205 (e.g., to appropriate flanges on cylinders 204 and 205). In some embodiments, cylinders 204 and 205 include closed ends (e.g., to seal gas springs 298 and 299, respectively) and do not need to include separate heads. In some embodiments, as shown, spacers 295 and 296 are positioned to provide axial space, and therefore volume, to respective gas springs 298 and 299. Spacers 295 and 296 may be bolted, fastened, or otherwise secured to respective cylinders 204 and 205, respective heads 208 and 209, or both. In some embodiments, spacers 295 and 296 are configured to function as ring compressors (e.g., during ring disassembly, inspection, or replacement). In some embodiments, spacers 295 and 296 may include two or more sections (e.g., a clamshell design). Cylinders 204 and 205 include respective low-pressure ports 230 and 240 for exchanging low-pressure gas (e.g., for exchanging low-pressure gas) and respective high-pressure ports 231 and 241 for exchanging high-pressure gas (e.g., for exchanging high-pressure gas). In some embodiments, low-pressure ports 230 and 240 are coupled to the environment by corresponding gas flows, referred to herein as "atmospheric breathing." In some embodiments, low-pressure ports 230 and 240 are coupled to a low-pressure reservoir or source (e.g., regulated atmosphere or other suitable gas reservoir or source above atmospheric pressure). For example, low-pressure ports 230 and 240 can be coupled to respective reservoirs 273 and 274, as shown. Reservoirs 273 and 274 can be configured to seal the back sections of pistons 214 and 224, respectively. As shown, reservoirs 273 and 274 are also sealed to bearing housings 217 and 227, respectively, and to cylinders 204 and 205, respectively.Reservoirs 273 and 274 may be sealed to any suitable component of the linear generator, including, for example, the frame, the stator, the gas spring head, any other suitable component, or any combination thereof. The volumes of reservoirs 273 and 274 may be sized to minimize or otherwise limit gas pressure fluctuations in their respective back sections. In some embodiments, filters may be installed at or upstream of low-pressure ports 230 and 240 to prevent ingestion of particles (e.g., dust or debris), certain molecules (e.g., water in some cases), or other undesirable gas source components. In some embodiments, cylinders 204 and 205 need not include low-pressure ports 230 and 240, high-pressure ports 231 and 241, or any ports at all. For example, in some embodiments, no high-pressure port is included, and low-pressure ports 230 and 240 are included to provide make-up gas to supplement blow-by passing through respective pistons 214 and 224 (e.g., may also be included in appropriate locations on the corresponding cylinders or cylinder heads, if applicable). In some embodiments, driver sections 250 and 258 can include mechanisms for removing energy from the generator system to protect against damage or failure (e.g., overpressure of gas spring 298 or 299, loss of seal in gas spring 298 or 299). Further details of such mechanisms are described in the context of FIG. 12. For example, either or both of cylinders 204 and 205 can include grooves (e.g., "scallops") configured to allow high-pressure gas to leak around seals (e.g., rings) if pistons 214 and 224 overtravel, resulting in loss of pressure and energy in the gas spring. In further examples, a pressure relief valve can be included and coupled to the gas spring to cause the gas spring to release energy (e.g., gas) if the pressure exceeds a design threshold.

[0033] Stator 218, magnet assembly 213, tube 212, and bearing housings 216 and 217 form linear electromagnetic machine (LEM) 256. Similarly, stator 228, magnet assembly 223, tube 222, and bearing housings 226 and 228 form LEM 252. Additionally, the LEM may optionally include one or more pistons. For example, the LEM may be defined to include stator 218, translator 210, and bearing housings 216 and 217. In a further example, the LEM may be defined to include stator 228, translator 220, and bearing housings 226 and 227. The LEM includes a mounting assembly (e.g., stator and bearing housing) and a translation assembly (e.g., translator) constrained to move along an axis, where the stator can apply an electromagnetic force to the translator to cause and / or effect movement along the axis. The bearing housing of the LEM may, but need not, be attached to the stator. For example, the bearing housing may be coupled to the stator, structural frame, or cylinder directly, by intervening components, or by any combination thereof. Stators 218 and 228 may include multiple phase windings forming multiple phases. The current in each phase may be controlled in time by a control system (which may include, for example, corresponding power electronics and processing equipment) to affect the position of translators 210 and 220, the movement of translators 210 and 220, the working interaction with translators 210 and 220, or any combination thereof. In some embodiments, magnet assemblies 213 and 223 include permanent magnets (e.g., alternating north and south poles) arranged in an array. Because translators 210 and 220 move as a substantially rigid assembly, electromagnetic forces applied to each magnet assembly 213 and 223 accelerate and decelerate translators 210 and 220.In some embodiments, stators 218 and 228 can be air-cooled (e.g., by an air-cooling system), liquid-cooled (e.g., by a liquid-cooling system), or both. In some embodiments, stators 218 and 228 are disposed around the respective translators 210 and 220 or their respective magnet assemblies 213 and 223 (e.g., the motor's air gap has an arcuate thickness profile). For example, stators 218 and 228 can extend completely (e.g., 360 degrees azimuthally) or partially (e.g., with azimuthally disposed segments and azimuthally disposed gaps between phase windings) around the respective translators 210 and 220. In some embodiments, stators 218 and 228 are disposed axially along the respective translators 210 and 220 or their respective magnet assemblies 213 and 223. For example, magnet assemblies 213 and 223 can include flat magnet sections, and stators 218 and 228 can include flat surfaces corresponding to the magnet sections (e.g., the air gap of the motor has a planar thickness profile). In some embodiments, stators 218 and 228 extend axially along their respective translators 210 and 220 or their respective magnet assemblies 213 and 223.

[0034] In some embodiments, generator assembly 200 includes one or more mechanisms to protect components of generator assembly 200 from damage due to mechanical failure, control failure, component failure, operation in extreme conditions, or a combination thereof. Bump stops 290 and 291 are positioned to convert kinetic energy from each translator 210 and 220 into deformation by contacting respective pistons 214 and 224 in the event of translator overtravel, as shown. For example, one or both of stators 218 and 228 can include one or more mechanisms to protect generator assembly 200. In some embodiments, one or both of stators 218 and 228 include one or more mechanisms (e.g., bump stops, mechanical springs, pneumatic pistons) configured to convert the translator kinetic energy into sound, heat, solid deformation, or a combination thereof, that slow, stop, or redirect the translator motion. For example, the bump stops may be configured to undergo plastic deformation (e.g., bend, compress, crush, puncture, or otherwise deform) upon contact with the translator to convert the kinetic energy of the translator. In some embodiments, one or more bump stops may be located on either or both of driver sections 250 and 258. In some embodiments, bump stops are included as part of other components of generator assembly 200, such as, for example, driver sections 250 and 258. In some embodiments, bump stops are located at each end of cylinder 202 near the BDC. The bump stops may be attached to the structural frame directly or with intervening components in any suitable location, to the cylinders (e.g., cylinders 203, 204, 205, or combinations thereof) directly or with intervening components in any suitable location, to the stator directly or with intervening components, or combinations thereof.In some embodiments, generator assembly 200 can include features or components for attachment to a structural frame (e.g., as shown in FIGS. 53-57 ). For example, cylinder assembly 254, driver sections 250 and 258, and LEMs 252 and 256 can include one or more features or components for attachment to the structural frame, one or more features or components for alignment to the structural frame, one or more components or features for alignment to another component away from the structural frame (e.g., LEM 252 to LEM 256, cylinder assembly 254 to LEM), or any combination thereof. In some embodiments, the features or components used to attach portions of generator assembly 200 to the structural frame can provide compliance in one direction (e.g., axial, lateral, or radial), stiffness in a different direction (e.g., axial stiffness while radial compliance), and allow for changes during operation.

[0035] 3 is a block diagram of an exemplary linear generator 300 including a control system 310 for controlling operation of the generator assembly 350, according to some embodiments of the present disclosure. The generator assembly 350 can include one or more stators, each including multiple windings corresponding to multiple phases (e.g., each phase including one or more windings). For example, a stator can include three or more phases, which can electromagnetically interact with a translator to apply forces to the translator. For example, the phases can apply forces to the translator in the same direction of motion (e.g., motoring) or opposite directions of motion (e.g., braking or generating electricity) or combinations thereof (alternating) over the course of a stroke or cycle. The current flow (e.g., direction and magnitude) in each winding, and therefore each phase (e.g., even when a phase includes multiple windings), can be controlled by the control system 310 and supplied / received using a power subsystem 322.

[0036] Control system 310 may include a processing unit 312, a memory 314, one or more communication interfaces 316, one or more user interfaces 318, a sensor interface 320, a power subsystem 322, any other suitable components or modules not shown, or any combination thereof. Control system 310 may be implemented, at least in part, in one or more computers, embedded systems, terminals, control stations, handheld devices, modules, any other suitable interface devices, or any combination thereof. In some embodiments, the components of control system 310 may be communicatively coupled via one or more communication buses 324, as shown in FIG. 3 .

[0037] In some embodiments, control system 310 is configured to control translator trajectory, control power output, control energy storage, control operating conditions, respond to electrical loads, manage the supply of intake gas to the cylinders, manage the removal of exhaust gas from the cylinders, ensure safe operation (e.g., perform diagnostics and detect faults), any other suitable function, or a suitable combination thereof (e.g., all of the foregoing).

[0038] In some embodiments, control system 310 receives information from one or more sensors 330, user input (e.g., at user interface 318), a reference database (e.g., a look-up table stored in memory 314), any other source, or any combination thereof, and determines a corresponding control response. For example, control system 310 can receive position information along with desired force information from sensors 330 associated with the translator and stator of generator assembly 350 and determine current values ​​for one or more phases of the electromagnetic machine. In some embodiments, control system 310 controls the current for each phase of the stator. In some embodiments, control system 310 controls the current for each phase based on position information (e.g., axial position, axial speed, axial acceleration), magnetic flux information, motor constant information (e.g., force constant, back EMF), any other suitable information, or any combination thereof. Control system 310 can control the magnitude of the current for each phase, the direction of the current for each phase, or both. Control system 310 can control the commutation of current in multiple phases.

[0039] Processing unit 312 may include a processor (e.g., a central processing unit), a cache, a random access memory (RAM), a read-only memory (ROM), any other suitable components, or any combination thereof, capable of processing information related to poly-phase electromagnetic machine 350. Memory 314 may include any suitable volatile or non-volatile memory, which may include, for example, random access memory (RAM), read-only memory (ROM), flash memory, a hard disk, any other suitable memory, or any combination thereof. Information stored in memory 314 may be accessed by processing unit 312 via communication bus 324. For example, computer-readable program instructions (e.g., for implementing the techniques disclosed herein) stored in memory 314 may be accessed and executed by processing unit 312. In some embodiments, memory 314 includes a non-transitory computer-readable medium for storing computer-executable instructions that cause processing unit 312 (e.g., a processing unit of a suitable computing system) to perform methods for controlling a generator assembly, an intake system, an exhaust system, a cooling system, a bearing system, a gas spring system, any other suitable system, or any combination thereof. For example, memory 314 may include computer-executable instructions for implementing any of the control techniques described herein.

[0040] In some embodiments, communication interface 316 includes a wired connection (e.g., using IEEE 802.3 Ethernet or Universal Serial Bus Interface Protocol), a wireless coupling (e.g., using IEEE 802.11 "Wi-Fi," Bluetooth, or over a cellular network), an optical coupling, an inductive coupling, any other suitable coupling, or any combination thereof, for communicating with one or more systems external to control system 310. For example, communication interface 316 may include a USB port configured to accept a flash memory drive. In further examples, communication interface 316 may include an Ethernet port configured to enable communication with one or more devices, networks, or both. In further examples, communication interface 316 may include a transceiver configured to communicate using any suitable standard over a cellular network.

[0041] In some embodiments, the user interface 318 includes a wired connection (e.g., using an IEEE 802.3 Ethernet or Universal Serial Bus interface, tip-ring-seal RCA-type connection), a wireless coupling (e.g., using IEEE 802.11 “Wi-Fi,” infrared, Bluetooth, or over a cellular network), an optical coupling, an inductive coupling, any other suitable coupling, or any combination thereof, for communicating with one or more user interface devices 326. The user interface device(s) 326 may include a display, a keyboard, a mouse, an audio device, any other suitable user interface device, or any combination thereof. For example, the display may include a display screen, such as a cathode ray tube screen, a liquid crystal display screen, a light-emitting diode display screen, a plasma display screen, any other suitable display screen, or any combination of such screens, capable of providing graphics, text, images, and other visuals to a user. Additionally, the display may include a touchscreen, capable of providing tactile interaction with a user, for example, by providing one or more soft commands on the display screen. In further examples, user interface device(s) 326 may include a keyboard, such as a QWERTY keyboard, a numeric keypad, any other suitable collection of hard command buttons, or any combination thereof. In further examples, user interface device(s) 326 may include a mouse or any other suitable pointing device capable of controlling a cursor or icons on a graphical user interface displayed on a display screen. In further examples, user interface device(s) 326 may include an audio device, such as a microphone, a speaker, headphones, any other suitable device for providing and / or receiving audio signals, or any combination thereof.In some embodiments, it is not necessary to include user interface 318, user interface device(s) 326, or both (e.g., control system 310 need not receive user input or provide output to a user). In some embodiments, user interface device(s) 326 include computing devices with which a user can interact. For example, user interface device(s) 326 may include a computer with a touchscreen, and a software application (e.g., a web portal hosted by an application server or other host system) may generate the display and process user input. In further examples, user interface device(s) 326 may be coupled to communication interface 316 (e.g., using a web-based application implemented over a network connection).

[0042] In some embodiments, the sensor interface 320 includes a power source (e.g., for powering the sensor(s) 330), a signal conditioner, a signal preprocessor, any other suitable components, or any combination thereof. For example, the sensor interface 320 may include one or more filters (e.g., analog and / or digital), amplifiers, samplers, and analog-to-digital converters for conditioning and preprocessing signals from the sensor(s) 330. In some embodiments, the sensor interface 320 communicates with the sensor(s) 330 via a communications coupling 332, which may be a wired connection (e.g., using an IEEE 802.3 Ethernet or Universal Serial Bus interface), a wireless coupling (e.g., using IEEE 802.11 "Wi-Fi" or Bluetooth), an optical coupling, an inductive coupling, any other suitable coupling, or any combination thereof.

[0043] Sensor(s) 330 may include any suitable type of sensor that may be configured to sense any suitable characteristic or aspect of generator assembly 350, any other system, or any combination thereof. In some embodiments, sensor(s) 330 include a linear encoder, a rotary encoder, or both configured to sense the relative position between a translator and a stator of generator assembly 350. In some embodiments, sensor(s) 330 include an accelerometer configured to sense acceleration of the translator relative to a fixed stator, vibration of a nominally static component, or any other suitable acceleration. In some embodiments, sensor(s) 330 include a camera configured to capture images (e.g., time-lapse imaging) of the translator relative to the stator of generator assembly 350. In some embodiments, the sensor(s) 330 include one or more current sensors (e.g., coupled to a phase of a stator of the generator assembly 350), one or more voltage sensors (e.g., coupled to a phase of a stator of the generator assembly 350), or both configured to sense voltage, current, work output and / or input (e.g., current multiplied by voltage), other suitable electrical properties of the linear generator, or any combination thereof. In some embodiments, the sensor(s) 330 include one or more temperature sensors, such as, for example, thermocouples, thermistors, resistance temperature detectors (RTDs), any other suitable sensors for detecting temperature, or any combination thereof. For example, the sensor(s) 330 may include thermocouples positioned to measure the temperature of power subsystem components such as permanent magnets, windings, transistors, cylinders, bearing housings, gases (e.g., intake gases or exhaust gases), or other components or fluids of the linear generator. In some embodiments, the control system 310 is configured to control the axial position of the translator of the generator assembly 350 during non-operating events (eg, when not generating power).For example, in some embodiments, the control system 310 is configured to move the translator axially outward and engage a locking mechanism (not shown) to lock the translator axially in place during maintenance, inspection, or removal, installation, or replacement of components of the generator assembly 350.

[0044] In some embodiments, sensor(s) 330 may be included in control system 310. In some embodiments, sensor(s) 330 may be partially or wholly integrated into generator assembly 350 (e.g., an encoder tape attached to a translator). In some embodiments, sensor(s) 330, sensor interface 320, or both may be removable from, external to, optionally omitted from, optionally installed in, or otherwise not included in control system 310. For example, sensor(s) 330 may include a piezoelectric pressure sensor with control circuitry separate from control system 310. Further to this example, control circuitry may optionally be integrated into control system 310.

[0045] In some embodiments, power subsystem 322 includes control circuitry, power electronics, an electrical load (e.g., for dissipating electrical energy for heating via a resistive load bank), a ground (e.g., chassis or earth ground), a terminal block, a power storage device (e.g., battery, capacitor), electrical bus lines for transmitting power, insulated gate bipolar transistors (IGBTs), mechanical relays, solid-state relays, power diodes, thyristors, metal-oxide semiconductor field-effect transistors (MOSFETs), any other suitable transistors, switches, contactors, fuses, pulse-width modulation controllers, digital-to-analog controllers, any other suitable electronic components, any other suitable controllers, or any combination thereof. Power subsystem 322 can receive control signals from processing unit 312 via communication bus 324 regarding generator assembly 350. For example, power subsystem 322 can include multiple IGBTs coupled to corresponding phase leads of multiple phases of a stator via power couplings 352. Illustratively, the IGBTs can be coupled to phase windings that can be coupled to high and low bus voltage lines and a wye neutral. In some embodiments, power coupling 352 includes one or more cables, leads, connectors, or a combination thereof. For example, each phase of the stator may be coupled to a corresponding terminal of power subsystem 322 via a respective cable. In some embodiments, power subsystem 322 includes a virtual phase that may correspond to current flow but does not correspond to any phase of the stator of generator assembly 350. In some embodiments, power subsystem 322 includes a grid-tie inverter (GTI) configured to manage power interaction between linear generator 300 and a power grid. For example, in some embodiments, power subsystem 322 may include a DC bus having a DC voltage managed by the GTI.In some embodiments, power subsystem 322 includes a battery, a capacitor, or both, for storing electrical energy from the linear generator system, an external power source (e.g., a power grid), or both, and for discharging the stored electrical energy to support operation of the linear generator system (e.g., for startup, for output loads). In an exemplary example, power subsystem 322 may include or be similar to electrical system 105 of Figure 1. Thus, with reference to Figure 1, control system 104 and electrical system 105 may be combined.

[0046] 3, the control system 310 may include one or more system interfaces for controlling, monitoring, receiving information from, or a combination of any suitable systems. For example, the control system may include a motor controller for controlling a boost blower motor. In a further example, the control system may include a motor controller for controlling a cooling system fan.

[0047] In an exemplary example, control system 310 may be configured to control force interactions between the translator and the stator. Force may be applied to the translator by controlling current (e.g., magnitude and direction) in one or more phases that electromagnetically interact with the translator. In some embodiments, a desired force is determined based on position information, velocity information, acceleration information, or a combination thereof, and control system 310 applies current to one or more phases to achieve the desired force on the translator (e.g., the achieved force may be, but is not required to be, equal to the required force). Encoders may be used to determine the position of the translator relative to the stator, the velocity of the translator (e.g., by calculating an appropriate time derivative or second derivative using any suitable analytical or numerical differentiation technique), the acceleration of the translator (e.g., by calculating a time derivative using any suitable analytical or numerical differentiation technique), any other suitable information, or any combination thereof.

[0048] In further illustrative examples, the control system 310 may be configured to control the storage, accumulation, and conversion of energy in the gas spring during operation of the linear generator system (e.g., during cycling of the generator assembly). In some embodiments, the operation of the gas spring may be adjustable (e.g., the amount of energy stored, the maximum pressure, or the minimum pressure may be adjustable). In some embodiments, a low-pressure port, a high-pressure port, or both may be utilized to control the characteristics of the gas spring. For example, the low-pressure port, the high-pressure port, or both may be used to control the amount of gas in the gas spring, the temperature, the pressure, other suitable characteristics, and / or any combination thereof. In some embodiments, adjusting any of the aforementioned characteristics, and therefore the total mass of the gas spring, may change the effective spring constant of the gas spring. The effective spring constant may depend, for example, on gas temperature, gas pressure, gas composition, quantities derived therefrom (e.g., density), or combinations thereof. For example, to change the energy stored, the effective spring constant, the displacement, or both may be changed. Two exemplary approaches include: (1) for a fixed effective spring constant (e.g., which may still include a known position dependency), displacement can be used to control the amount of energy stored in the gas spring; and (2) for a fixed displacement (e.g., fixed TDC and BDC positions), effective spring constants can be used to control the amount of energy stored in the gas spring. To illustrate, in some embodiments, control system 310 is configured to control the axial displacement of the translator to control the storage of energy in the gas spring. For example, control system 310 can control the BDC position of the translator during a stroke (i.e., the outer apex position, which is the TDC of the gas spring) to store a desired amount of energy in the corresponding gas spring (e.g., at least an amount of energy sufficient to perform the subsequent stroke without requiring a net electrical input during the subsequent stroke).Further, in some circumstances, a more outer BDC position may correspond to a relatively large amount of energy stored in the gas spring (e.g., such that it is possible to provide enough energy to perform a subsequent stroke while still producing a net electrical output from the generator assembly 350 to the power subsystem 322 during the subsequent stroke). Additionally, the control system 310 may determine or estimate the energy required to perform the subsequent stroke and may control the energy storage in the gas spring to store at least the energy required during the expansion stroke (i.e., during expansion of the reaction section and simultaneous compression of the gas spring). In some embodiments, one or more parameters associated with the auxiliary system are adjusted to effect flow into or out of the gas spring. For example, the gas spring supply tank pressure, regulator pressure, or other parameters may be adjusted to effect gas flow into (e.g., flow into) or out of (e.g., flow from) a low-pressure port or high-pressure port of the gas spring system.

[0049] In some embodiments, the geometry of the gas spring can be adjusted to obtain a desired operation. For example, the volume of the gas spring can be increased or decreased by controlling the gas exchange with the gas spring through the low-pressure port, the high-pressure port, or both, and the characteristics of the gas flowing therethrough. In some embodiments, the dead volume within the cylinder can be adjusted to change the spring constant of the gas spring (e.g., another form of affecting the position or volume change of the gas spring). It will be appreciated that any of the above controls and adjustments of the gas spring therein can provide control over the amount of energy stored by the gas spring during the expansion stroke of the generator assembly. It will also be appreciated that the above control of the characteristics of the gas spring can provide variability in the frequency of the generator assembly's cycles.

[0050] In some embodiments, the exhaust system can be tuned along with the intake system to affect the breathing process. In some embodiments, one or more intake runners and one or more exhaust tuned pipes can be configured to provide a breathing process with specific breathing characteristics. For example, one or more intake runners and one or more exhaust tuned pipes can include a predetermined length, diameter, or both to generate desired breathing characteristics. In an exemplary embodiment, the desired breathing characteristics can include an instantaneous pressure profile in the intake manifold and an instantaneous pressure profile in the exhaust manifold that draws intake gases into the bore (e.g., high intake manifold pressures generated when an exhaust suction wave occurs). In a further exemplary embodiment, the desired breathing characteristics can include a plugging pulse from the exhaust system that limits, reduces, or prevents substantial blow-through of unreacted fuel in the exhaust (e.g., prevents fuel in the exhaust gases from increasing by more than 1 part per million, 10 parts, 100 parts, or 1000 parts). The desired breathing characteristics may allow for lower boost pressure (e.g., produced by boost blower 704 in FIG. 7), lower blower power requirements, lower emissions, higher indicated power, higher indicated efficiency, less fuel consumption, or a combination thereof.

[0051] In some embodiments, the exhaust system, intake system, and generator assembly can be configured to exhibit desired breathing characteristics. For example, the axial placement and design of the intake and exhaust breathing ports (e.g., the location of the breathing ports along the axis of the cylinder), the intake system design (e.g., the size and shape of the intake manifold or the type of fuel injection strategy), the exhaust system design (e.g., the size and shape of the exhaust manifold or the adjusted pipe length), and the intake boost pressure, along with other appropriate system characteristics and operating modes, can affect the breathing characteristics. In some embodiments, the desired breathing and exhaust characteristics can be achieved by configuring various geometric characteristics, such as the open / closed position of the intake breathing ports, the length and cross-sectional area of ​​the intake runner, the open / closed position of the exhaust breathing ports, the adjusted pipe length and cross-sectional area, the length and cross-sectional area of ​​the exhaust runner, the manifold volume and length scale, or any combination thereof. It will be understood that the opening and closing of a port is referred to in the context of its coupling to the compression / expansion volume (e.g., before a seal, such as the front portion of the piston). For example, a port may be closed by the piston but still open to a volume behind the piston seal near the translator tube (e.g., the reaction backsection). In a further example, the opening or closing of a port refers to the path of gas exchange between the respective manifolds / plenums and the volume of the cylinder bore between the intake and exhaust ports. To illustrate, the volume "V" of the compression / reaction section may be given by: V=A cyl (x ip +x ep ) where "Acyl" is the nominal cross-sectional area of ​​the bore, "x ip ” is the axial position of the intake piston face, “x ep" is the axial position of the exhaust piston, measured from the centerline of the cylinder (e.g., axial centerline 207 in Figure 2). The volume behind the piston may also be compressed and expanded depending on the circumstances. Breathing characteristics, such as the amplitude of the blowdown pulse, plugging pulse, and suction wave, and their timing during the breathing process, can be influenced by the geometric characteristics of the system. Additionally, operating characteristics can be configured to induce desired breathing characteristics and may include the intake gas pressure generated by the boost blower, the gas pressure in the bore when the exhaust breathing port is open, the equivalence ratio, the top dead center (TDC) position of the piston face when the reaction cylinder volume is minimum (e.g., near the center) during the operating cycle, the bottom dead center (BDC) position of the piston face when the reaction cylinder volume is maximum (e.g., away from the center of the cylinder) during the operating cycle, fuel pressure, and the frequency of the translator's reciprocating motion (e.g., the inverse of the cycle time). For example, the positions of TDC and BDC can affect the timing and duration of the breathing process. In a further example, the equivalence ratio can affect the amplitude of the blowdown pulse and the wave characteristics in the adjusted pipe. In some embodiments, the TDC position of the piston face can be adjusted relative to the centerline to affect breathing, the BDC position can be adjusted relative to the port to affect breathing, or both. For example, in an opposed piston configuration, the TDC and BDC positions of each translator can be adjusted to affect breathing or other engine performance.

[0052] 4 illustrates a portion of an exemplary generator assembly 400 with reaction section pistons 410 and 420 at various respective axial positions in accordance with some embodiments of the present disclosure. The intake piston 410 and the exhaust piston 420 move within the bore of a cylinder 405 along an axis 406. The axial positions of the reaction section pistons 410 and 420 may be referenced to any suitable datum, including, for example, an axial centerline 407. An intake port 415 and an exhaust port 425 are axially disposed at respective positions on the cylinder 405. The axial positions of the intake port 415 and the exhaust port 425 may be, but need not be, equidistant from the axial centerline 407. For example, as illustrated, the exhaust port 425 is closer to the axial centerline 407 than the intake port 415.

[0053] Panel 490 shows an exemplary breathing initiation, with intake piston 410 with seal 411 positioned axially inside intake port 415 (e.g., intake port 415 just open to volume 401 of cylinder 405). Panel 491 shows exhaust piston 420 with seal 421 positioned just axially within axial range of exhaust port 425 (e.g., exhaust port 425 partially open to volume 401 of cylinder 405).

[0054] Panel 491 shows intake piston 410 with seal 411 positioned axially outboard of intake port 415 (e.g., intake port 415 opens to volume 402 of cylinder 405). Panel 491 shows exhaust piston 420 with seal 421 positioned axially outboard of exhaust port 425 (e.g., exhaust port 425 opens to volume 401 of cylinder 405).

[0055] Panel 492 shows intake piston 410 with seal 411 positioned axially at the opening and closing threshold of intake port 415 near the end of breathing (e.g., intake port 415 is closed to volume 401 of cylinder 405). Panel 492 shows exhaust piston 420 with seal 421 positioned axially toward the center of exhaust port 425, as exhaust port 425 is axially further inboard than intake port 415.

[0056] Panel 493 shows intake piston 410 with seal 411 positioned axially inside intake port 415 at the end of breathing and the beginning of compression (e.g., intake port 415 is closed to volume 401 of cylinder 405). Panel 493 shows exhaust piston 420 with seal 421 positioned axially inside exhaust port 425. Panel 493 shows both intake port 415 and exhaust port 425 closed to volume 401.

[0057] FIG. 5 illustrates a portion of an example generator assembly 500 with lean fronting, according to some embodiments of the present disclosure. Lean fronting is a process in which relatively lean intake gases "lead" relatively rich intake gases during the breathing process, thereby reducing blow-through, lowering the residual mass fraction (RMF), or both. For example, during the breathing process, it may be desirable for the slug of intake gases entering the cylinder to have a relatively lean portion at the beginning and end. The relatively lean portion reduces the tendency for fuel to blow through to the exhaust system near the end of the breathing process. For example, this non-uniform intake gas concentration profile may allow for a smaller amount of trapped residual exhaust gas while restricting or eliminating the flow of fuel through. In some embodiments, control of piston position in time may allow for control of the breathing behavior. For example, synchronization of opposing piston positions may allow for the timing of port opening and closing to generate desired breathing behaviors (e.g., blowdown pulses, section pulses, plugging pulses, or other behaviors). In further examples, lean fronting may allow for greater boost pressure and reduced RMF (e.g., resulting in increased power density, compression ratio, other operating performance, or a combination thereof). Panel 590 shows reaction piston section 510 (e.g., intake piston) with seal 511 and reaction section piston 520 (e.g., exhaust piston) with seal 521 toward the end of the breathing process. Intake gases include a fuel and air mixture entering volume 501 of cylinder 505 through intake port 515, as shown. The intake gases displace exhaust gases formed during the reaction of gases in the previous cycle. The displaced exhaust gases exit volume 501 through exhaust port 525. At the end of the breathing process, some exhaust gas remains in volume 501. This residual gas is referred to as residual gas and, when considered along with the trapped intake gases at the end of the breathing process, may be characterized by RMF. In some embodiments, reduced RMF is desired.Panel 591 illustrates the end of breathing (e.g., the beginning of compression) with lean fronting applied to generator assembly 500. Residual gas, lean front, and aft-end intake gas are trapped in volume 501. The lean front and aft-end intake gas together are the "intake gas." Lean fronting allows for axial stratification of gas in volume 501 and prevents fuel in the aft-end intake gas from exiting exhaust port 525 during breathing. In an exemplary embodiment, lean fronting can be achieved using the configuration shown in FIGS. 16-17.

[0058] In some embodiments, the injector may be configured to inject gas fuel, liquid fuel, or both. For example, the injector may be configured to inject natural gas, methane, propane, biogas, hydrogen, or other suitable gas fuel into the intake system. In some embodiments, for example, the injector may include a carburetor-type injector configured to inject fuel at a relatively low supply pressure. The injector may inject fuel at a constant rate, a variable rate, a rate dependent on local intake gas pressure, a frequency (e.g., pulsed), other suitable time schedule, or any combination thereof. For example, the injector may exhibit pulsed operation, continuous operation, pulsed operation aligned with piston position, any other suitable operating mode, or any combination thereof. The injector may induce or experience any suitable flow characteristics (e.g., average or local flow velocity, pressure drop, or other characteristics) and may be controlled using any suitable control technique based on any suitable flow characteristics. For example, the injector may be driven by pulse width modulation (PWM), pulse density modulation (PDM), DC pulses (e.g., from an injector drive), any other suitable actuation technique, or any combination thereof. In further examples, the drive signal to the injector may be controlled based on fuel flow rate, fuel pressure, boost pressure, in-runner pressure, in-cylinder pressure, pressure drop (e.g., across the injector or other suitable component), exhaust composition, load requirements (e.g., electrical output of a linear generator), reaction timing (e.g., advance, maintain, or retard timing), translator position (e.g., related to opening or closing a port), breathing characteristics (e.g., timing and amplitude of pressure waves during breathing), any other suitable operating parameter, or any combination thereof.

[0059] It will be appreciated that the above description is merely exemplary and that any suitable geometric, operational, or other system characteristics may be configured to affect breathing characteristics.

[0060] 6 shows two cross-sectional views of an exemplary translator having a reservoir, according to some embodiments of the present disclosure. For example, panels 600 and 650 show an exemplary enlarged cross-section behind seals 262 and 263 of FIG. 2. In further examples, pistons 211 and 221 of FIG. 2 can include a collar, a diffuser, a reservoir, a restriction, or a combination thereof, as described in the context of FIG. 6.

[0061] Panel 600 illustrates a translator including a tube 622, a piston 620, a seal 621 (e.g., a piston ring), and a collar 610, all of which are substantially rigidly coupled to move as a substantially rigid body along the axis of a cylinder 602. Cylinder 602 includes a bore 603 configured to accommodate a reaction section 697. As shown, piston 620 is attached to collar 610 using fastener 613, and collar 610 is attached to tube 622 using fastener 614. Panel 650 illustrates a translator including a tube 672, a piston 670, a seal 671 (e.g., a piston ring), and a collar 660, all of which are substantially rigidly coupled to move as a substantially rigid body along the axis of cylinder 652. As shown, piston 670 is attached to collar 660 using fastener 663, and collar 660 is attached to tube 672 using fastener 664.

[0062] As shown in panel 600, collar 610, together with bore 603, forms reservoir 606, which influences the flow of blow-by gas bearings. Collar 610 also, together with bore 603, forms restriction 612 (e.g., a labyrinth restriction as shown), which influences the flow of gas from reservoir 606. For example, if a leak path opens at seal 621, relatively hot gas from reaction section 697 may erupt along bore 603, potentially causing axially asymmetric thermal deformation of tube 622 (e.g., at approximately the same azimuthal position as the leak path). Collar 610 is configured to reduce the velocity of the leaking gas (e.g., blow-by gas) and distribute the gas azimuthally to reduce asymmetric thermal deformation downstream of the collar (e.g., to the translator tube). As shown in panel 600, piston 620 includes diffuser 624. A diffuser 624 may optionally be included to improve the effectiveness of reservoir 606 by slowing the velocity of leak gas before it reaches reservoir 606. Reservoir 606 includes a volume that extends azimuthally around collar 610, allowing for the accumulation and azimuth distribution of leak gas. Restriction 612 restricts the flow of gas exiting reservoir 606, allowing the leak gas to accumulate in reservoir 606. As shown in panel 600, restriction 612 extends azimuthally around collar 610 and includes a labyrinth restriction that provides some appropriate axial pressure drop and azimuth distribution to each groove of the labyrinth.

[0063] As shown in panel 650, collar 660 forms a reservoir 656 with bore 603, which influences the flow of blow-by gas bearings. Collar 660 includes restriction 662, which includes a ring that restricts the flow of gas along tube 672 exiting reservoir 656. In some embodiments, a ring restriction, such as restriction 662, provides an improved thermal path to bore 603 of cylinder 602. In some embodiments, one or more ring restriction may be included to provide a greater pressure drop, although adding ring restriction may increase frictional losses. In some embodiments, restriction 662 may be configured to not be energized by leaking gas and have limited or no contact with bore 603. In some embodiments, restriction 662 may be configured to not contact bore 603 during normal operation. In some embodiments, restriction 662 may include a mechanism configured to create swirl (e.g., azimuthal distribution) downstream of collar 660 to further reduce asymmetric thermal deformation of tube 672. In some embodiments, the restriction 662 can include one or more gear-shaped teeth and grooves azimuthally around the collar 660 to further distribute the flow downstream of the collar. For example, the collar can include a labyrinth restriction (e.g., restriction 612), a contact or non-contact ring restriction (e.g., restriction 662), a restriction with a mechanism that provides a swirl downstream of the one or more gear-shaped teeth and grooves, any other suitable restriction, or any combination thereof.

[0064] Although shown as separate components, piston 620 and collar 610 (e.g., or piston 670 and collar 660) may be a single component (e.g., the piston may form a reservoir with a cylinder bore), separate components (e.g., as shown), or a collection of three or more components (e.g., a multi-part collar). In some embodiments, collar 610 may include a diffuser, a reservoir, and a restriction, or any combination thereof. In some embodiments, piston 620 may include a diffuser, a reservoir, and a restriction, or any combination thereof. The collar, or collar-like sections of the piston, may comprise any suitable material, such as, for example, metal, ceramic, plastic, composite, any other suitable material, or any combination thereof. In some embodiments, piston 620 is comprised of a high-temperature alloy metal (e.g., Inconel), and collar 610 is comprised of a different type of metal. In some embodiments, collar 610 is comprised of a metal with a similar thermal expansion coefficient as fasteners 613 and 614.

[0065] The intake system is configured to bring reactants to the cylinder of the generator assembly. For example, the intake system may be configured to provide a controlled air-fuel mixture to the cylinder during breathing (e.g., intake and exhaust of gases from the bore of the cylinder). In further examples, the intake system may be configured to provide a controlled amount of air (e.g., via breathing) and a controlled amount of fuel (e.g., via direct injection, near-port injection, or other suitable fuel injection type) to the cylinder. In further examples, the intake system may be configured to provide a controlled amount of air / fuel mixture to the cylinder. In still further examples, the intake system may be configured to provide a controlled amount of air to the cylinder and separately provide a controlled amount of fuel to the cylinder. The intake system may be configured to provide reactants under appropriate conditions, such as appropriate pressure, temperature, velocity, composition (e.g., equivalence ratio, humidity, residual trapped exhaust gas, exhaust gas recirculation content), or other suitable characteristics, or any combination thereof. Figures 7-17 illustrate exemplary intake systems and components thereof according to the present disclosure. While the following description primarily relates to air, it will be understood that the present disclosure may be applied to any intake gas (e.g., contaminated air, oxygen, other oxidizers, inerts, or other gases) in accordance with the present disclosure. It will also be understood that the present disclosure may be applied to any suitable fuel, including gaseous fuels, liquid fuels, aerosolized fuels, slurry fuels, any other suitable fuel, or any suitable combination thereof.

[0066] 7 shows a system diagram of an exemplary air intake system 700 according to some embodiments of the present disclosure. Air intake system 700 optionally includes, for example, a filter 702, a boost blower 704, an intercooler 706, a manifold system 710, corresponding ducts (e.g., runners and fittings), sensors, any other suitable components, or any suitable combination thereof.

[0067] Filter 702 is configured to restrict one or more components of the intake gas supply from entering the remainder of intake system 700 and the corresponding generator assembly. As shown, filter 702 is positioned upstream of boost blower 704, intercooler 706, and manifold system 710. In some embodiments, filter 702 is positioned downstream of intercooler 706 and upstream of manifold system 710. In some embodiments, filter 702 is positioned downstream of boost blower 704 or any other suitable location in the intake system. In some embodiments, multiple filters 702 may be included and positioned at various locations in the intake system. For example, filter 702 may be configured to filter particles, dust, particulate matter, debris, humidity (e.g., dry or agglomerated type filters), or other materials that may be in the intake gas supply. Filter 702 may include any suitable number of filters (e.g., one or more) arranged in any suitable configuration (e.g., in series or parallel, at one or more locations along the intake system). For example, multiple filters can be used in series, parallel, or a combination thereof.

[0068] The boost blower 704 is configured to increase the pressure of the intake air, the velocity of the intake air, or both. For example, the boost blower 704 may allow the intake air to more completely purge the exhaust air from the cylinder during a breathing process (e.g., during a uniflow scavenging process). In a further example, the boost blower 704 may allow for higher in-cylinder pressure when the port is closed, thereby increasing the power density of the generator system (e.g., by increasing trapped pressure, reducing residual gas trapping, or both). The boost blower 704 may include any suitable type of blower, such as, for example, a centrifugal blower, a positive displacement compressor, a fan, a reciprocating compressor, any other suitable compressor having any number of suitable stages, or any suitable combination thereof. In some embodiments, the boost blower 704 includes an electric motor configured to drive a compressor directly (e.g., direct drive) or indirectly (e.g., using gears, belts, pulleys, and other linkages). In some embodiments, for example, boost blower 704 includes a centrifugal compressor driven by an electric motor. For example, the electric motor may be driven by a variable frequency drive (e.g., controlled by control system 310 of FIG. 3 ). In some embodiments, boost blower 704 includes a centrifugal compressor coupled via a shaft to a radial gas turbine (e.g., as a turbocharger coupled to the intake and exhaust systems). In some embodiments, for example, referring to FIG. 2 , boost blower 704 may be replaced or supplemented by diverted air from gas springs 298 or 299 of driver sections 258 and 250, respectively. In some embodiments, boost blower 704 provides air or an air-fuel mixture at a desired pressure to manifold system 710.The linear generator system may include any suitable type of boost blower (e.g., turbocharger, supercharger), any suitable number of boost stages (e.g., one or more compression stages), with any suitable auxiliary systems (e.g., intercooling system, oil system, blow-off safety system) in accordance with the present disclosure.

[0069] The intercooler 706 is configured to cool the intake air, intake fuel, or air-fuel mixture downstream of the boost blower 704. The boost blower 704 typically increases the temperature of the intake gases from the work input, for example, due to thermodynamic and / or mechanical inefficiencies. This increase in temperature is generally undesirable because it reduces the density of the intake gases and, in some cases, can affect the amount of trapped mass that can be achieved in the cylinder and can also affect ignition of the reaction section. For example, an increase in the gas temperature of the trapped gases can cause compression ignition to occur relatively early, reduce the operating compression ratio, or both, each of which can be undesirable. The intercooler 706 can be air-cooled (e.g., by an air-cooling system), liquid-cooled (e.g., by a liquid-cooling system), or both. In some embodiments, the intercooler 706 includes a radiator-style heat exchanger with a fan to blow gas (e.g., atmospheric air) across cooling fins. In some embodiments, the intercooler 706 can be enclosed and may include flowing fluid-to-flowing fluid heat transfer (e.g., a cross-flow heat exchanger, a counter-flow heat exchanger, or a parallel-flow heat exchanger). In some embodiments, the intercooler 706 includes one or more heat pipes configured to transfer heat from the intake gas. For example, a liquid-filled heat pipe may be used to transfer heat from the intake gas with or without a phase change. In further examples, the heat pipe may be closed with no inflow or outflow flow (e.g., a sealed tube containing a fluid that operates via capillary effect). In further examples, the heat pipe may be open and allow fluid to flow (e.g., include a flow path and a separate heat sink). The intercooler 706 may include any suitable intercooling fluid capable of accepting energy from the intake gas. For example, the intercooling fluid may include water, air, propylene glycol, ethylene glycol, a refrigerant, a corrosion inhibitor, any other suitable fluid, any other suitable additive, or any combination thereof.

[0070] The manifold system 710 is configured to interface with the cylinder and manage the flow of intake gas to the intake breathing ports of the cylinder. The intake gas can include intake air, fuel (e.g., gaseous or dispersed droplets), an air-fuel mixture, an oxidizer-fuel mixture, along with any other suitable fluid, such as, for example, recirculated exhaust gas, water vapor, or other suitable fluid. In some embodiments, the manifold system 710 includes a runner, a swirl inducer, a mixing inducer, a flow divider, or other mechanism capable of collecting, distributing, mixing, or otherwise providing suitable intake gas to the bore of the cylinder. In some embodiments, the intake system need not include a manifold, but can include a plenum or other suitable component. In some embodiments, the manifold system 710 is configured to operate in coordination with the intake ports of the cylinders of the generator assembly to supply intake gas to the cylinders.

[0071] In some embodiments, a fuel system is configured to supply fuel to intake system 700. As shown in FIG. 7, the fuel system is not included as part of the intake system; however, in some embodiments, the fuel system may be integrated into intake system 700. In some embodiments, fuel is supplied downstream of filter 702, downstream of boost blower 704, downstream of intercooler 706, or to manifold system 710 to form the intake air mixture (e.g., before flowing through the intake breathing ports). In further examples, in some embodiments, fuel is supplied to manifold system 710 for manifold injection, near-port injection, port injection, or a combination of injection configurations. In some embodiments, intake system 700 need not be coupled to a fuel system. For example, fuel injection can be directly into the bore of the cylinder (e.g., direct injection). Further details regarding fuel systems are included, for example, in the discussion in the context of FIG. 15.

[0072] It will be understood that an integrated linear generator system may include any, all, or none of the components discussed in the context of the intake system. For example, the intake breathing port of the generator assembly may be coupled to the atmosphere (e.g., to achieve natural aspiration). Figures 4-17 show exemplary breathing ports and breathing port configurations, which may correspond to any of the intake breathing ports, exhaust breathing ports, and gas spring breathing ports.

[0073] FIG. 8 illustrates a side view of an exemplary breathing port 820 in a cylinder 810, according to some embodiments of the present disclosure. FIG. 9 illustrates an axial cross-sectional view of the exemplary cylinder 810 of FIG. 8, according to some embodiments of the present disclosure. As illustrated, the breathing port 820 includes a plurality of exemplary rectangular openings (e.g., axially elongated) extending through the sidewall of the cylinder 820 and positioned axially on the cylinder 810 (e.g., with end or center positions aligned with specific spatial positions along the axial direction of the cylinder). Also illustrated in FIGS. 8-9 is a piston ring 830 positioned such that the piston ring 830 axially overlaps the breathing port 820 (e.g., the port is open or partially open). In some embodiments, as illustrated, the piston ring 830 includes a ring gap 831. If the ring gap 831 is azimuthally clocked so that it is covered by one of the port bridges 811 (i.e., the solid material between the ports of the breathing port 820), the end of the piston ring 830 is supported during axial movement along the length of the breathing port. However, if the ring gap 831 clocks (e.g., rotates azimuthally about an axis defining the axial direction) the breathing port of the breathing port 820 (e.g., as shown in Figures 8-9), there can be a significant risk of radial movement and shear stress (e.g., potentially damaging the end of the piston ring 830). In some circumstances, breathing ports with large azimuth openings (e.g., short bridges) have a relatively high likelihood of the ring gap being misaligned with the bridge. In some embodiments, the ring includes an anti-rotation feature to prevent the ring from clocking so that the ring gap remains azimuthally aligned with the port bridge.

[0074] FIG. 10 illustrates a side view of an exemplary breathing port 1020 in a cylinder 1010 sized and positioned to reduce ring stress, according to some embodiments of the present disclosure. The exemplary breathing port 1020 in FIG. 10 includes staggered holes (e.g., a hexagonal arrangement as shown) separated by port bridges 1011, each hole having a diameter smaller than the azimuthal width of the breathing port 820 in FIG. 8. The scale of the breathing port 1020 (e.g., the diameter as shown) is relatively smaller than the scale of the breathing port 820, making it less likely that the ring gap will be fully seated in the breathing port of the breathing port 1020 (e.g., at least a portion of the ring gap is always covered by the bridge). In some embodiments, with a relatively small port size, the ring does not need to be pinned or otherwise restrained against rotation within the piston ring groove (e.g., it does not need to include an anti-rotation feature). The bridges in FIG. 10 resemble webs more than those shown in FIG. 8. Thus, the ports and corresponding bridges may be any suitable shape. In some embodiments, the relatively large port openings of breathing ports 820 of Figure 8 can be used. For example, large openings (e.g., larger than the length scale of the ring, such as the axial thickness) can reduce flow losses due to surface friction. In some embodiments, the relatively small, staggered openings of breathing ports 1020 of Figure 10 can be used. For example, small openings (e.g., smaller than the length scale of the ring, such as the axial thickness) can help reduce the likelihood of ring damage. In some embodiments, alternative port shapes can be used to meet one or more competing criteria, including, for example, improved breathing and improved ring wear. For example, in some embodiments, the ports can have a rectangular shape similar to the ports shown in FIG. 8, but each port has a narrower width in the lateral or azimuthal direction and / or a longer dimension in the axial direction (e.g., similar to an oval). These oval or other rectangular ports can provide a larger open surface area compared to breathing port 1020, while providing greater ring wear characteristics compared to breathing port 820. The cylinder can include any suitable port shape and size, or combination of shapes and sizes, according to the present disclosure. For example, the ports can include holes, slots, ellipses, polygons, rounded polygons, compound-shaped openings, any other suitable openings, or any combination thereof. In some embodiments, the size and / or shape of the breathing port can be configured to reduce the pressure drop of gases flowing through the port, prevent an unsupported ring gap, reduce ring wear, induce a desired breathing behavior, or a combination thereof. In some embodiments, the breathing port can be sufficiently long axially so that the piston seal does not move completely axially outward of the breathing port. For example, when the piston is at BDC, the port can be sufficiently long (axially outward from TDC) so that at least a portion of the port is open to the front of the piston's sealing ring (e.g., allowing exhaust gases in the cylinder to enter the exhaust manifold) and at least a portion of the port is open to the back of the piston's sealing ring (e.g., allowing gases in the back section of the piston to exit the cylinder and enter the exhaust manifold).

[0075] FIG. 11 shows a cross-sectional end view of an exemplary shaped breathing port 1120 in a cylinder 1110, according to some embodiments of the present disclosure. The breathing port 1120 includes a larger cross-sectional area on the outer surface (e.g., the outside of the cylinder 1110) than on the inner surface (e.g., the bore cylinder 1110). FIG. 12 shows a cross-sectional end view of an exemplary shaped breathing port 1220 in a cylinder, according to some embodiments of the present disclosure. The breathing port 1220 includes a smaller cross-sectional area on the outer surface (e.g., the outside of the cylinder 1210) than on the inner surface (e.g., the bore cylinder 1210). For example, in some embodiments, the intake breathing port can be shaped similar to the breathing port 1120 shown in FIG. 11 to reduce pressure loss across the port compared to sharp edges (e.g., to reduce the boundary layer of flow passing through the port from outside to inside). In further examples, in some embodiments, the exhaust breathing port can be shaped similarly to the breathing port 1220 shown in FIG. 12 to reduce pressure loss across the port compared to sharp edges (e.g., to reduce the boundary layer of flow passing through the port from inside to outside). Therefore, the expected direction of the average flow can provide guidance on how the breathing port should be contoured to reduce losses (e.g., the port should be shaped as a nozzle rather than a diffuser relative to the flow direction). In some embodiments, the breathing port can include a composite shape of those shown in FIGS. 11-12 (e.g., having a wide-narrow-wide cross-sectional area profile). For example, the breathing port can include a compound curve, a piecewise profile, any other suitable profile, or any combination thereof. In some embodiments, the breathing port can include an azimuthal path or feature (e.g., to introduce an azimuthal component or “swirl” into the flow). In some embodiments, the breathing port can include an axial path or feature (e.g., tilted axially forward or backward to introduce an axial component into the flow).

[0076] FIG. 13 illustrates an axial cross-sectional view of an exemplary integrated linear generator system portion 1300 configured for premixed air and fuel, according to some embodiments of the present disclosure. The integrated linear generator portion 1300 includes a cylinder 1302 and a manifold 1304. The cylinder 1302 includes an intake breathing port 1310. For purposes of discussion, four intake breathing ports 1310 spaced 90 degrees apart are illustratively shown in FIG. 13 , but any suitable number of intake breathing ports may be included with any suitable spacing and separation, according to the present disclosure. The intake breathing ports may be shaped to reduce ring wear and / or to direct the flow of air or fuel mixture. In some embodiments, the intake ports may be replaced with a design including multiple smaller diameter holes or any other suitable shape. For example, smaller diameter holes (such as those shown in FIG. 10 ) may reduce piston ring wear and improve uniform premixed air and fuel injection into the manifold. Premixed air and fuel enter the manifold 1304, are distributed to the volume between the manifold 1304 and the cylinder 1302 (referred to herein as the "manifold volume"), enter the intake breathing port 1310, and flow into the bore 1303 when the corresponding piston opens the intake breathing port 1310, and a pressure field directs the flow into the bore 1303 (e.g., during the breathing process). During an engine cycle, the flow in the manifold volume can be unsteady due to the opening and closing of the intake breathing port 1310 by the piston (not shown in FIG. 13), the opening and closing of the exhaust breathing port by the piston (not shown in FIG. 13), or both. In some embodiments, the manifold volume, manifold geometry, or both can be selected to enhance breathing, make the flow field more symmetrical between the intake breathing ports, reduce pressure loss, introduce swirl, swirl, or a combination thereof. For example, features such as crevices can be used to promote swirl and swirl. Providing swirl or swirl can improve scavenging of residual gases from the reaction cylinder bore and / or improve intake fuel and air mixing.The seal 1320 is configured to seal between the manifold 1304 and the cylinder 1302. For example, the seal 1320 may include a gasket, an O-ring, a bead of cured sealant, a press fit, any other suitable seal, or any combination thereof. In some embodiments, the breathing port 1310 is sized so that the flow experiences a greater pressure drop through the breathing port 1310 than within the manifold volume. In some embodiments, the manifold 1304 may be sized to ensure a desired level of air-fuel mixing (i.e., uniformity) prior to intake into the cylinder 1302.

[0077] FIG. 14 illustrates a cross-sectional view of an exemplary integrated linear generator system portion 1400 configured for near-port or in-port injection according to some embodiments of the present disclosure. The integrated linear generator portion 1400 includes a cylinder 1402 and a manifold 1404. The cylinder 1402 includes an intake breathing port 1410. For clarity, four intake breathing ports 1410 spaced 90 degrees apart are illustratively shown in FIG. 14 , but any suitable number of intake breathing ports may be included with any suitable separation according to the present disclosure. Air enters the manifold 1404, is distributed to the manifold volume between the manifold 1404 and the cylinder 1402, enters the intake breathing port 1410, and flows into the bore 1403 when the corresponding piston opens the intake breathing port 1410, and the pressure field directs the flow into the bore 1403 (e.g., during the breathing process). During an engine cycle, flow within the manifold volume can be unsteady due to the opening and closing of intake breathing ports 1410 by pistons (not shown in FIG. 14 ) and the opening and closing of exhaust breathing ports by pistons (not shown in FIG. 14 ). In some embodiments, the manifold volume, manifold geometry, or both can be selected to enhance breathing, make the flow field more symmetrical between the intake breathing ports, reduce pressure loss, introduce swirl, swirl, or a combination thereof. The fuel injectors 1430 are configured to deliver fuel to corresponding intake ports of the intake breathing ports 1410. In some embodiments, each of the intake breathing ports 1410 can have a corresponding fuel injector (e.g., similar to fuel injector 1430), but this is not required. In some embodiments, the fuel injectors 1430 are configured to deliver fuel for a predetermined period of time. For example, the fuel injector 1430 may be configured to inject fuel only during the breathing process (eg, when the intake breathing port 1410 is opened by the corresponding piston).In further examples, the fuel injector 1430 may be configured to inject fuel only during a time window of the breathing process to limit the amount of fuel that does not enter the bore 1403 during the breathing process (e.g., to prevent fuel from accumulating in the manifold 1404), limit the amount of fuel that blows through the cylinder during the breathing process (e.g., to prevent fuel from entering or leaving the bore 1403 during the breathing process), or both. In some embodiments, the fuel injector 1430 is configured to deliver fuel continuously. Although shown as being partially inserted into one of the intake breathing ports 1410, the fuel injector 1430 need not be inserted into one of the intake breathing ports 1410. For example, the fuel injector 1430 may be aimed at the intake breathing port and generate a jet of fuel that enters the intake breathing port due to momentum effects (e.g., jet velocity). The fuel injector 1430 may include any suitable type of fuel injector capable of delivering fuel to the intake breathing port. For example, the fuel injector 1430 may be configured for near-port injection, in-port injection, or both. The seal 1420 is configured to seal between the manifold 1404 and the cylinder 1402. For example, the seal 1420 may include a gasket, an O-ring, a bead of cured sealant, a press fit, any other suitable seal, or any combination thereof. Although shown sealing directly against the cylinder 1402, the seal 1420 need not directly engage the cylinder 1402. For example, the seal 1420 may seal against another component of the integrated linear generator system (e.g., a bearing housing, a rod seal).

[0078] FIG. 15 shows a cross-sectional view of an example integrated linear generator system portion 1500 configured to inject fuel upstream of an intake breathing port 1510, according to some embodiments of the present disclosure. The integrated linear generator portion 1500 includes a cylinder 1502, a manifold 1504, a plenum 1531, intake runners 1591-1594, a fuel injector 1530, and a seal 1520. The seal 1520 is configured to seal between the manifold 1504 and the cylinder 1502 (e.g., to prevent leaks between the intake system). For example, the seal 1520 may include a gasket, an O-ring, a bead of cured sealant, a press fit, any other suitable seal, or any combination thereof. In some embodiments, the fuel injector 1530 is configured to inject fuel into the plenum 1531, which receives intake air (e.g., from a boost blower and / or intercooler, and / or a filter). The air and fuel mixture flows from plenum 1531 through intake runners 1591, 1592, 1593, and 1594 to corresponding intake breathing ports 1510. In some embodiments, intake runners 1591-1594 have the same or similar lengths, thus providing similar residence times for intake gases within each intake runner. For example, intake runners 1591-1594 can be tailored (e.g., have geometric characteristics such as length and cross-sectional area) to have flow paths that result in particular breathing characteristics. The air and fuel mixture is further discussed in the context of FIG. 18. An intake system can include any suitable number (e.g., one or more) of plenums, fuel injectors, breathing ports, and breathing enhancement features in any suitable arrangement according to the present disclosure.

[0079] In some embodiments, the intake runners 1591-1594 are sealed to corresponding ports in the intake breathing port 1510 so that the intake gas flow in the intake runners does not leak into the manifold 1504. In some embodiments, the plenum 1531 is open to the manifold 1504 (e.g., the plenum 1531 and the manifold 1504 are the same). In some embodiments, the manifold 1504 need not be included (e.g., the intake runners 1591-1594 are sealed to the plenum 1531). In some embodiments, the intake runners 1591-1594 need not directly engage the cylinder 1502 or the intake breathing port 1520. For example, the ends of the intake runners 1591-1594 may be located near the respective intake breathing port 1520 but may not be sealed.

[0080] FIG. 16 shows a diagram of an exemplary intake manifold arrangement 1600 according to some embodiments of the present disclosure. Arrangement 1600, shown from the side of the generator assembly toward the intake side, illustrates a partitioned intake. The partitioned intake is an approach for selectively injecting a relatively lean or rich air / fuel mixture into the reaction cylinder during the breathing process (e.g., lean fronting). As shown, air and fuel are supplied to intake manifold 1610. Screen 1650 and partition 1660 separate regions 1611 and 1612 from each other. Fuel is supplied to region 1611 (e.g., using injector 1670), and air is supplied to region 1612. Screen 1650 allows a portion of the air from region 1612 to enter region 1611 and mix with the fuel there. Thus, the gas mixture in region 1611 is richer than the gas mixture in region 1612 (e.g., the equivalence ratio of region 1611 is greater than the equivalence ratio of region 1612). Divider 1660 provides axial partitioning of the intake gas flow into the bore of cylinder 1602. Divider 1660 may be porous, perforated, or gas-permeable (e.g., indicated by the arrows) as shown, but provides at least some restriction to mixing between regions 1611 and 1612. The placement of region 1612 axially inward of region 1611 (toward TDC as shown) allows relatively lean intake gases to enter the bore of cylinder 1602 during breathing. This axial partitioning of the intake gases can reduce the concentration of unreacted fuel in the exhaust gases due to blow-through. For example, when the exhaust port is closed, the intake gas charge in the bore of cylinder 1602 can be relatively lean toward the exhaust side of cylinder 1602. In some embodiments, the partition 1660 extends radially inward to the outer surface of the cylinder 1602 at the intake port 1603. In some embodiments, the partition 1660 is sealed to the intake manifold by a seal 1661, as shown.

[0081] In an exemplary embodiment, during a power stroke of the linear generator, the intake translator 1620 moves away from TDC (e.g., away from the exhaust breathing port). When the seal ring opens the intake breathing port 1603, gas from region 1612 of the intake manifold 1610 begins to enter the cylinder 1602. Region 1612 closest to the centerline of the cylinder 1602 contains gas with a relatively low concentration of fuel. When the translator 1620 begins to open the intake breathing port 1603, the gas in region 1612 enters the cylinder 1602 first. Fuel is injected (e.g., using an injector 1670) into region 1611 farther from the centerline of the cylinder 1602 (e.g., away from TDC), causing region 1611 to contain a more fuel-rich zone. Gas in region 1611 enters cylinder 1602 later in the breathing cycle because it takes longer for translator 1620 to open that portion of intake breathing port 1603 corresponding to region 1611. Screen 1650 can be used to control the relative flow of fresh air from region 1612 to region 1611. For example, the porosity or open area of ​​screen 1650, the position of screen 1650 (e.g., axial or radial position), the porosity or open area of ​​partition 1660, the position of partition 1660 (e.g., axial position of partition 1660), or a combination thereof, affect the partitioning of intake gases flowing from intake manifold 1610 to cylinder 1602.

[0082] 17 illustrates a cross-sectional side view of an exemplary intake section 1700 of a linear generator according to some embodiments of the present disclosure. Intake section 1700 is similar to intake section 1600, except that divider 1760 is impermeable to intake gases, whereas divider 1660 is permeable to intake gases. As illustrated, air and fuel are provided to region 1711 of intake manifold 1710. Screen 1750 and divider 1760 separate regions 1711 and 1712 from each other. Fuel and air are provided to region 1711, and air is provided to region 1712. Screen 1750 allows the intake gases to be partitioned into a first stream of air provided to region 1612 and a second stream of air or air and fuel provided to region 1711. In some embodiments, screen 1750 partitions intake air into regions 1711 and 1712, and fuel is provided to region 1711 using optional fuel injector 1770. Thus, the gas mixture in region 1711 is richer than the gas mixture in region 1712 (e.g., the equivalence ratio of region 1711 is greater than the equivalence ratio of region 1712). For example, the equivalence ratio of region 1712 may be zero or near zero (e.g., region 1712 may contain air without fuel). Divider 1760 provides an axial partition for the flow of intake gases into the bore of cylinder 1702. Divider 1760 is impermeable to intake gases (e.g., as indicated by the arrows) and prevents mixing between regions 1711 and 1712. The placement of region 1712 axially inward of region 1711 (toward TDC as shown) allows relatively lean intake gases to enter the bore of cylinder 1702 during breathing. This axial partitioning of the intake gases can reduce the concentration of unreacted fuel in the exhaust gases due to blow-through. For example, when the exhaust port is closed, the intake gas charge in the bore of cylinder 1702 can be relatively lean toward the exhaust side of cylinder 1702. In some embodiments, partition 1760 extends radially inward to the outer surface of cylinder 1702 at intake port 1703. In some embodiments, partition 1760 is sealed to the intake manifold by seal 1761, as shown.

[0083] FIG. 18 shows a system diagram of an exemplary fuel system 1800 according to some embodiments of the present disclosure. In some embodiments, air intake system 400 includes fuel system 1800. In some embodiments, fuel system 1800 need not be included in the air intake system. Fuel system 1800 illustratively shown in FIG. 18 includes a fuel filter 1802, a fuel compressor 1804, and a fuel valve 1806. Fuel system 1800 receives a suitable fuel from a fuel supply, which may include, for example, a tank (e.g., a propane tank, a diesel tank, a storage tank), a pipe or pipeline (e.g., a natural gas or biogas pipeline), or any other suitable fuel source. In an exemplary example, fuel system 1800 may be the same as the fuel system of FIG. 7.

[0084] The fuel filter 1802 is configured to filter unwanted components from the fuel, such as, for example, water, particulate matter, condensable vapors, sulfur, siloxanes, or other components. In some embodiments, the fuel system 1800 need not include the fuel filter 1802. For example, the fuel supply, source, or reservoir can provide sufficient composition or cleanliness to the fuel and therefore does not require further filtering (e.g., utility pipeline natural gas). The optional fuel compressor 1804 is configured to increase the pressure of the fuel. In some embodiments, the fuel compressor 1804 is configured to significantly increase the pressure of the fuel for use with high-pressure drop fuel injectors (e.g., for gas or liquid fuels). In some embodiments, the fuel compressor 1804 is configured to provide a relatively small increase in pressure. For example, the fuel valve 1806 can include a carburetor-type fuel valve, and the fuel compressor 1804 can increase the pressure of the fuel enough for the fuel valve 1806 to operate. In some embodiments, fuel system 1800 need not include fuel compressor 1804. For example, the fuel supply, source, or reservoir may be able to provide fuel at sufficient pressure and therefore not require additional boost. Fuel compressor 1804 may be selected based on the fuel injection technology used. For example, fuel compressor 1804 may be capable of generating a relatively high pressure (e.g., much greater than the boost pressure of the intake gas) to achieve direct injection or near-port injection over an appropriate time scale (e.g., a time scale less than the cycle period). In further examples, fuel compressor 1804 need not be capable of generating high pressure, but rather may generate a pressure greater than the air boost pressure, particularly if the time scale of injection is relatively long or if fuel injection is continuous.In some embodiments, one or more gas springs (e.g., 204 and / or 205 of FIG. 2), gas spring reservoirs (e.g., 273 and / or 274 of FIG. 2), or combinations thereof may be configured to compress fuel to supplement, complement, or negate the need for fuel compressor 1804.

[0085] The exhaust system is configured to facilitate the removal of reaction products from the cylinder to the atmosphere. For example, the exhaust system is configured to induce the removal of reaction products during breathing. FIGS. 17-19 illustrate exemplary exhaust systems and components thereof according to the present disclosure. The exhaust system can be configured to reduce or prevent blow-through (i.e., intake gases entering the intake breathing ports and exiting the exhaust breathing ports during the breathing process). For example, blow-through can allow unreacted fuel to reach the exhaust system in some circumstances. Additionally, the exhaust system can be configured to assist in drawing intake gases into the cylinder during the breathing process.

[0086] FIG. 19 shows a system diagram of an exemplary exhaust system 1900 according to some embodiments of the present disclosure. The exhaust system 1900 optionally includes, for example, an exhaust manifold system 1902, tuned piping 1910, a stinger 1912, optional emission / noise pollution devices 1914, corresponding ducting, sensors, any other suitable components, or any suitable combination thereof. In some embodiments, the exhaust system 1900 can include a heat exchanger (not shown in FIG. 19 ) to generate useful thermal energy that can be later utilized or stored for cogeneration applications, additional power generation (e.g., via a bottoming cycle), other thermal applications, or any combination thereof. Exhaust gases flow from the bore of a cylinder through exhaust breathing ports (not shown in FIG. 19 and covered by the manifold system 1902) to the manifold system 1902 when released by the corresponding piston (e.g., during the breathing process). In some embodiments, when the piston opens the exhaust breathing port, the gas pressure in the cylinder is higher than the gas pressure in the manifold system 1902 (e.g., in some circumstances, sufficient to create choked flow at the exhaust breathing port), causing a blowdown pulse (e.g., a pressure wave propagating through the exhaust gases). The tuned pipe 1910 is configured to utilize the blowdown pulse (e.g., the energy of the pressure wave) to enhance the breathing process. For example, the tuned pipe 1910 may be configured to generate a suction pulse (e.g., to help draw intake gases into the cylinder) and a plugging pulse (e.g., to reduce blow-through and increase in-cylinder pressure) in response to the blowdown pulse during the breathing process. Thus, the transient breathing process and the tuned pipe cause the flow in the manifold system 1902 to become unsteady. The blowdown pulse, suction pulse, and plugging pulse are examples of pressure waves (e.g., having pressure peaks, valleys, or other characteristics) propagating through the exhaust system and the gases in the cylinder bore.

[0087] The tuned pipe 1910 includes a runner 1904, a diverging section 1906, an optional section 1907 having a fixed cross-sectional area, and a converging section 1908. In some embodiments, the runner 1904 can include a length of duct having a fixed diameter, cross-sectional area, or both at both ends of the tuned pipe 1910 (e.g., separate from section 1907). In some embodiments, the diverging section 1906 has a predetermined length, a predetermined first diameter or cross-sectional area, and a predetermined second diameter or cross-sectional area. For example, the diverging section 1906 can be shaped as a hollow frustum section (e.g., a regular or oblique frustum) with a smaller cross-sectional area closer to the manifold system 1902. The converging section 1908 is downstream of the diverging section 1906 and can be shaped as a hollow frustum section (e.g., a regular or oblique frustum) with a smaller cross-sectional area facing downstream. The length, cross-sectional area, and placement of the tuned pipe 1910 can affect the performance of the generator assembly, particularly the breathing process. For example, the length of the tuned pipe 1910 can be configured to affect the breathing characteristics (e.g., the timing of the suction wave or plugging pulse). In some embodiments, the section 1907 includes a constant diameter. In some embodiments, the spatial dimensions of the tuned pipe can be determined based on the desired operating characteristics of the linear generator, such as, for example, power output, air and / or fuel flow, operating frequency, emissions, or any other suitable operating characteristic. In some embodiments, the tuning of the tuned pipe 1910 is specific to or otherwise based on the operating frequency of the generator assembly. For example, the timing and phase of the pressure wave can be tuned to a particular engine frequency or frequency range. In an exemplary example, the generator assembly can be configured to operate over a relatively limited frequency range, to which the tuned pipe 1910 is tuned. For example, the tuned pipe 1910 may be tuned to a frequency range of 10%, 20%, 30%, 40%, or 50% less than ideal load to full load.

[0088] Downstream of the converging section 1908 is a stinger 1912. In some embodiments, the stinger 1912 comprises a duct having a relatively smaller diameter or cross-sectional area than the portion of the tuned pipe 1910. The stinger 1912 can be positioned at any suitable location in the tuned pipe 1910 and provides an outlet for exhaust gases to flow out of the tuned pipe 1910. In some embodiments, the diverging section 1906 connects to an expansion volume (e.g., an expansion tank) that replaces section 1907 and the converging section 1908, and the stinger 1912 is connected to such expansion volume.

[0089] An optional emissions / noise pollution device 1914 is disposed downstream of the stinger 1912. The emissions / noise pollution device 1914 may be configured to assist in balancing the chemical composition of the exhaust (e.g., by selectively catalyzing a reaction), reducing noise output, or both. For example, in some embodiments, the emissions / noise pollution device 1914 includes an oxidation catalyst configured to assist in the oxidation of unburned hydrocarbons, carbon monoxide, or any other suitable fuel or partial combustion products. In a further example, in some embodiments, the emissions / noise pollution device 1914 includes a three-way catalyst configured to assist in the oxidation of unburned hydrocarbons, carbon monoxide, or any other suitable fuel or partial combustion products, as well as the reduction of nitrogen oxides (e.g., to reduce NOx content). In a further example, in some embodiments, the emissions / noise pollution device 1914 includes a selective catalytic reduction (SCR) system configured to assist in the reduction of nitrogen oxides. In some embodiments, the emission / noise pollution device 1914 includes an SCR system, a catalyst, a muffler, a combination thereof, or none of these components. In some embodiments, the exhaust system need not include the emission / noise pollution device 1914. For example, an exhaust breathing port or tuned pipe can vent directly to the atmosphere. In some embodiments, the exhaust system need not include a muffler, and an exhaust duct is used to muffle noise. In some embodiments, the volume or space of the package (e.g., the enclosure of the linear generator system) is used to muffle noise, and a separate muffler component need not be included (e.g., excluding a muffler may provide more available space within the package / enclosure). In some embodiments, the emission / noise pollution device 1914 includes a suitable duct inside or outside the package / enclosure (e.g., an acoustic duct), a sound-deadening or acoustic panel, any other suitable mechanism configured to reduce the intensity of sound waves, another suitable mechanism configured to reduce audible noise outside the package, or any combination thereof.

[0090] The tuned pipe may include simple bends, compound bends, or both, of any suitable path and shape, according to some embodiments of the present disclosure. For example, the tuned pipe may be bent, wrapped, coiled, or otherwise reduced or modified in overall footprint to accommodate packaging constraints.

[0091] FIG. 20 illustrates an axial cross-sectional view of an exemplary integrated linear generator system portion 2000 configured for exhaust gas use, according to some embodiments of the present disclosure. The integrated linear generator portion 2000 includes a cylinder 2002 and a manifold 2004. The cylinder 2002 includes an exhaust breathing port 2010. For clarity, four exhaust breathing ports 2010 spaced 90 degrees apart are illustratively shown in FIG. 20; however, any suitable number of exhaust breathing ports may be included, with any suitable spacing and separation, according to the present disclosure. While shown as having a single outlet, the exhaust manifold may include any suitable number of outlets (e.g., one or more outlets). The exhaust breathing port may be shaped to reduce ring wear and / or to direct exhaust flow (e.g., as described in the context of FIGS. 11 and 12). In some embodiments, the exhaust port may include multiple small-diameter holes or any other suitable shape, which may reduce piston ring wear and improve uniform flow to the manifold (e.g., as described in the context of FIGS. 8-12). Exhaust gases flow out of the bore 2003, into the manifold 2004, and into the volume between the manifold 2004 and the cylinder 2002 (referred to herein as the "manifold volume") when the corresponding piston opens the exhaust breathing ports 2010 and a pressure field directs flow from the bore 2003 (e.g., during the breathing process). The flow in the manifold volume can be unsteady due to the opening and closing of the exhaust breathing ports 2010 by the piston (not shown in FIG. 20) during the engine cycle. In some embodiments, the manifold volume, the manifold geometry, or both can be selected to enhance breathing, make the flow field more symmetrical between the exhaust breathing ports, reduce pressure loss, introduce swirl, or a combination thereof. The seal 2020 is configured to seal between the manifold 2004 and the cylinder 2002. For example, the seal 2020 can include a gasket, an O-ring, a bead of cured sealant, a press fit, any other suitable seal, or any combination thereof.

[0092] In some embodiments, the exhaust manifold and exhaust breathing ports are designed to merge the flow from all exhaust breathing ports into one or more outlets in the hopes of maintaining low pressure loss, efficient transmission of pressure waves, a substantially uniform azimuthal pressure profile, a substantially uniform azimuthal temperature profile, or any combination thereof. In some embodiments, this performance is achieved by avoiding sharp bends or abrupt changes in the cross-sectional area of ​​the manifold system. In an exemplary embodiment, each exhaust breathing port may include a respective flow path defined by one or more curved vanes extending from the cylinder port bridge. The curved vanes direct the flow of exhaust gas from each exhaust breathing port into an annular volute. The flow from each exhaust breathing port merges sequentially with the volute, the cross-sectional area of ​​which increases along its length to accommodate the combined flow. The volutes (e.g., one, two, or more volutes) transition into a single outlet (e.g., a D-shaped outlet) with a total cross-sectional area at least as large as the total area of ​​the ports. FIG. 21 shows a cross-sectional view of an exemplary exhaust manifold 2100 according to some embodiments of the present disclosure. The exhaust manifold 1900 includes an internal joint 2101 configured to seal against a cylinder, vanes 2102, and an outlet 2103. In some embodiments, the exhaust manifold 1900 is configured to maintain a sufficiently smooth (e.g., uniform) azimuthal pressure field, a sufficiently smooth (e.g., uniform) azimuthal temperature field, or both. For example, a more uniform pressure field can help maintain a more uniform flow of exhaust gases (e.g., and thus more uniform convective heating of components). In a further example, a more uniform temperature field can help maintain a more azimuthal uniform temperature profile (e.g., and thus thermal expansion or deformation) of components. In some embodiments, the exhaust manifold 1900 helps eliminate or otherwise reduce translator bending due to the effects of uneven heating (e.g., which can result in bearing housing misalignment and increased wear).In some embodiments, the exhaust system can include a translator cooling system for providing cooling to the exhaust translator. For example, a compressed gas flow can be used to impinge on or otherwise flow along the surfaces of the translator to provide convection cooling. In some embodiments, cooling gas is provided to one or both of the intake and exhaust translators to provide translator cooling. In some embodiments, the translator cooler can include a mechanism configured to preferentially cool the surfaces of the translator. For example, the translator cooler can be configured to preferentially cool one or more surface regions of the translator over one or more other surface regions of the translator. For example, the translator cooler can include a mechanism configured to preferentially cool one or more sides of the translator closest to the exhaust manifold gas exit location (e.g., the top right of FIG. 20 or the top of FIG. 21). In some embodiments, the translator cooler can include a mechanism configured for uniform cooling of the translator.

[0093] A gas spring (GS) system is configured to convert energy from the corresponding translator motion into potential energy used to at least decelerate the translator during an expansion stroke. In some embodiments, the GS system is used to at least partially return the translator (e.g., from BDC). In some embodiments, the GS system is used to partially return the translator (e.g., from BDC), to provide compressed gas for use in other areas of the linear generator system (e.g., the bearing system), or both. In some embodiments, the gas spring system is configured to store a sufficient amount of energy during the expansion stroke to at least fully return the translator (e.g., from BDC to TDC) for a subsequent stroke so that no net electrical input is required. For example, the gas spring gas can include air, which can be provided in air bearings that interface with one or more translators. The gas spring system can include a gas spring assembly (i.e., hardware including a cylinder) that houses a gas spring (i.e., a volume of suitable gas capable of operating in a boundary action fashion). For example, as the translator moves away from TDC (i.e., moving outward from the center), the pressure in the respective gas spring increases (e.g., during the compression stroke of the gas spring and the expansion stroke of the reaction section). The compressive action exerted by the translator on the gas spring is at least partially stored as internal energy of the gas within the gas spring. This stored energy can then be converted to work (e.g., electrical energy) during the same stroke, a subsequent stroke (e.g., during expansion of the gas spring), or both. In some embodiments, a control system is configured to manage the storage and release of energy in one or more gas springs.For example, in some embodiments, the control system is configured to manage the storage and conversion of energy in one or more gas springs to avoid the need for a net electrical energy input throughout the stroke (i.e., to provide a net electromagnetic work output throughout the stroke), such that the integrated linear generator system extracts net electrical energy from the generator assembly from each stroke of the cycle. In a further example, in some embodiments, the control system is configured to avoid the need for an electrical energy input during the stroke, and always extracts electrical energy during each stroke of the cycle. Specifically, when the translator undergoes an extension stroke, the kinetic energy of the translator is both partially converted to electrical power by the LEM(s) and partially converted to internal energy stored in the gas spring. Furthermore, when the translator undergoes a compression stroke, the energy stored in the gas spring is partially converted to kinetic energy of the translator, which is partially converted to electrical energy by the LEM(s), and partially converted to internal energy in the reaction section (e.g., used to compress the reaction mixture). In some embodiments, the control system is configured to provide net electrical energy to the generator assembly, for example, when the free-piston linear generator is operating as a motor (e.g., during startup). For example, net electrical energy can be input to augment energy (e.g., kinetic energy, internal energy, and potential energy) in the linear generator system before introducing fuel. In some embodiments, the LEM can operate as an electric motor, in which case the control system is configured to supply electrical energy to the translator to move the translator to a desired position. For example, the electrical energy can be used by the stator to cause or assist actuation of the translator to a desired position closer to or farther from a position the translator would have reached without the input of electrical energy.In some embodiments where there is a net electrical output over the cycle, there may be time intervals during the cycle where electrical energy is input to the generator assembly (e.g., short periods of motoring rather than generating electricity).

[0094] A gas spring system may include, for example, a pair of gas springs. Each gas spring assembly may include a gas spring cylinder having a bore, a cylinder head, a low-pressure port, a high-pressure port, a valve, a filter, a sensor, any other suitable components, or any suitable combination thereof. In some embodiments, an integrated linear generator system may include a single gas spring assembly. For example, if a single translator is included, a single corresponding gas spring assembly may be included. In some such embodiments, a cylinder head may be included to seal the reaction section. In some embodiments, an integrated linear generator system may include two gas spring assemblies, and only one of the two gas spring assemblies includes a low-pressure port, a high-pressure port, or both. In some embodiments, an integrated linear generator system may include two gas spring assemblies, each including a respective low-pressure port and a respective high-pressure port. In some embodiments, the low-pressure ports of all gas springs in an integrated linear generator system may be in fluid communication (e.g., connected via a common reservoir or piping), and the high-pressure ports of all gas springs in the integrated linear generator system may be in fluid communication, or both. In some embodiments, the low pressure ports of some gas springs in an integrated linear generator system may be in fluid communication (e.g., connected via a common reservoir or piping), the high pressure ports of some integrated gas springs in an integrated linear generator system may be in fluid communication, or both. In some embodiments, the low pressure ports are not in fluid communication, the high pressure ports are not in fluid communication, or both. In some embodiments, the high pressure port of one or more gas springs can be used to partially or completely supply compressed gas for gas bearings (e.g., translator bearings, anticlocking bearings) used in the integrated linear generator system.In some embodiments, a low-pressure gas spring outlet port can be used to partially or completely supply air to the intake system to reduce or eliminate the power required by the intake boost blower. In some embodiments, a reservoir can be used to reduce pressure waves caused by translator vibrations (e.g., from the backside of the gas spring piston). In some embodiments, the reservoir can include a low-pressure inlet port that provides make-up air to the gas spring, a low-pressure outlet port that supplies gas (e.g., air) to the intake system, or both. In some embodiments, the reservoir can be configured to reduce pressure waves, sound, noise, or any combination thereof (e.g., infrasonic pressure waves).

[0095] 22 shows a cross-sectional view of an exemplary gas spring system 2200 according to some embodiments of the present disclosure. The gas spring system 2200 includes a gas spring cylinder 2202 having a bore 2203, a piston 2250 (e.g., part of a translator 2252), a low-pressure port 2204, a high-pressure port 2205, a valve 2215, and a cylinder head 2206. In some embodiments, the gas spring 2298 is a volume formed between the piston face 2251 and the gas spring cylinder 2202 and cylinder head 2206. The seal 2253 is configured to seal gas between the piston 2250 and the bore 2203, although in some embodiments, the seal 2253 is not required. In some embodiments, the seal 2253 includes a seal ring assembly (e.g., formed from graphite, plastic, metal, or other suitable material and configured to wear against the bore 2203, an oiled seal ring, or any other suitable seal ring). In some embodiments, seal 2253 is configured for oil-less operation (e.g., sealing without the use of oil or liquid for lubrication). Gas spring 2298 is configured to store and release energy during compression and expansion, respectively, as the gas pressure within gas spring 2298 changes.

[0096] In some embodiments, low pressure port 2204 is configured to allow gas to enter bore 2203 when piston 2250 (e.g., it and seal 2253) opens low pressure port 2204. In some embodiments, low pressure port 2204 is configured for near atmospheric breathing (e.g., 1 atmosphere ±0.5 atmospheres), during which atmospheric air is drawn into bore 2203 (e.g., where the pressure in bore 2203 is less than atmospheric). For example, at the end of the stroke (e.g., gas spring expansion) as the translator moves from BDC to TDC, the gas pressure in gas spring 2298 may be less than atmospheric at or near BDC due to losses. To explain, mass loss can occur from gas spring 2298 passing through seal 2253, referred to herein as "blow-by," or through high-pressure port 2205 via valve 2215, referred to herein as "high-pressure breathing." In some embodiments, gas from behind seal 2253 (i.e., away from piston face 2251) can interact with low-pressure port 2204. For example, in some circumstances, gas behind seal 2253 can flow between low-pressure port 2204 and the volume behind piston 2250 (i.e., driver back section 2270). In some embodiments, driver back section 2270 is open to near atmosphere. In some embodiments, driver back section 2270 can be open to near atmospheric pressure (e.g., 1 atmosphere ± 0.5 atmospheres). In some embodiments, driver back section 2270 can be sealed from near atmospheric pressure. For example, a gas seal can seal between translator 2252 and gas spring cylinder 2202. In further examples, driver back section 2270 can be sized to reduce or limit the compressive effect of gas within driver back section 2270 during a stroke of the cycle. In some embodiments, low pressure port 2204 is configured for boost air breathing, during which boost air at above atmospheric pressure is drawn into bore 2203. For example, a boost blower can be used to supply inlet air (e.g., make-up air) to low pressure port 2204, which provides make-up air to gas spring 2298. In some embodiments, low pressure port 2204 is located in or near cylinder head 2206 (e.g., still located within cylinder 2202). Any suitable number of low pressure ports 2204 having any suitable size, location, or both can be included in the gas spring system. In some embodiments, low pressure port 2204 is valved or otherwise controllable with respect to being "open" or "closed." In some embodiments, the low pressure port 2204 is configured to allow gas to exit the gas spring 2298 .For example, the gas spring system can include a first low pressure port for supplying make-up air to the gas spring 2298, and a second low pressure port for supplying air from the gas spring 2298. In an exemplary embodiment, the low pressure port can be used to supply reaction intake air (e.g., with an appropriate boost pressure by using a timed valve).

[0097] High pressure port 2205 is configured to allow gas in gas spring 2298 to exit bore 2203 when the gas pressure in gas spring 2298 exceeds a threshold value. In some embodiments, valve 2215 is configured to prevent gas flow until the pressure in gas spring 2298 exceeds a threshold value. The threshold value may be, for example, a pressure downstream of valve 2215, a cracking pressure of valve 2215, or any other suitable threshold value. In some embodiments, high pressure port 2205 is configured to provide high-pressure gas to a system outside bore 2203. For example, in some embodiments, high pressure port 2205 may be coupled to a gas bearing system and may supply bearing gas to the bearing system. Thus, in some embodiments, the gas spring system may also function as a gas compressor. Valve 2215 may include any suitable type of valve, such as, for example, a check valve, a reed valve, or any other suitable passive (e.g., spring-loaded) or active (e.g., actuated) valve. In some embodiments, the BDC position is closer to head 2206 than high pressure port 2205. For example, in some embodiments, during a stroke to the BDC position, the seal 2253 can move past the high pressure port 2205, and therefore the gas spring 2298 may not transmit significant pressure at the high pressure port 2205. In some embodiments, if the pressure in the gas spring 2298 exceeds a threshold value and the seal 2253 is not blocking the high pressure port 2205 and is closer to the head 2206 than the high pressure port 2205, gas from the gas spring 2298 can flow through the valve 2215. In an exemplary implementation, the peak pressure of the gas spring 2298 achieved at or near BDC may be 20 bar or more, while the gas outlet valve 2215 may be 6 bar or less. This example is merely illustrative, and any suitable location of the high pressure port 2205 and BDC may be used to achieve any suitable pressure within the gas spring 2298 (e.g., from a few bar to well over 50 bar). Any suitable number of pressure ports 2215 having any suitable size, location, or both may be included in the gas spring system.The high pressure port 2205 may be located in the cylinder 2202, the cylinder head 2206, any other suitable component, or any combination thereof (e.g., multiple high pressure ports, or a port formed in the mating surface of a component).

[0098] In some embodiments, the gas spring system need not include a high-pressure port. For example, the gas spring system may include a low-pressure port to provide make-up air during the breathing process to counteract blow-by during compression and expansion of the gas spring 2298 (e.g., to maintain approximately consistent cycle-to-cycle operation). In further examples, the low-pressure port may include a valve (e.g., located on the gas spring cylinder or head) coupled to a gas source, supply, or reservoir and configured to allow make-up gas to enter the bore during the breathing process. The low-pressure port (e.g., make-up air port) may be located in any suitable location, including, for example, in the cylinder head (e.g., configured to open only when the translator is near TDC) or in the cylinder wall.

[0099] In some embodiments, the gas spring system need not include a low pressure port. For example, in some embodiments, when the piston 2250 is near the TDC position, air from behind the piston 2250 (i.e., the driver back section 2270 away from the piston face 2251) can flow past the seal 2253 and into the gas spring 2298.

[0100] In some embodiments, the gas spring system need not include a low pressure port or a high pressure port.

[0101] In some embodiments, gas spring system 2200 can include one or more mechanisms 2232 for removing energy from gas spring 2298, limiting the peak pressure of gas spring 2298, limiting the compression ratio of gas spring 2298, limiting the expansion ratio of gas spring 2298, or combinations thereof. In some embodiments, gas spring system 2200 includes pressure relief valve 2231, which may optionally include, for example, pressure relief valve 2230. In some embodiments, pressure relief valve 2230 is configured to open when the pressure in gas spring 2298 exceeds a threshold value. For example, pressure relief valve 2230 can include a spring-loaded valve that opens when the pressure in gas spring 2298 is sufficient to overcome the spring force. Pressure relief port 2231 can be included to protect against overpressure conditions in gas spring 2298 by releasing energy from gas spring 2298 (e.g., to reduce the force acting on translator 2252). Optional pressure relief ports 2231 may be included in the cylinder head 2206, the gas spring cylinder 2202, or both. Any suitable number of pressure relief ports with any suitable cracking pressure may be included in the gas spring system.

[0102] In some embodiments, gas spring system 2200 includes a pressure relief mechanism 2232. For example, pressure relief mechanism 2232 may include one or more axial grooves or scallops included in the bore of cylinder 2202 configured to provide a leak path around seal 2253 (i.e., as blow-by) if seal 2253 moves past pressure relief mechanism 2232 (e.g., to a more distal BDC position). One or more of the length, axial position, and depth of pressure relief mechanism 2232 may be configured to introduce and maintain a leak path relative to a predetermined position of piston 2250. In some embodiments, the inclusion of one or more pressure relief mechanisms 2232 may provide pressure relief for gas spring 2298 without the need for mechanical or moving parts (e.g., pressure relief valve 2230, etc.).

[0103] In some embodiments, seal 2253 allows backflow when the pressure in driver back section 2270 is greater than the pressure in gas spring 2298. For example, seal 2253 can seal against bore 2203 when the pressure in gas spring 2298 is greater than the pressure in driver back section 2270 (e.g., greater than or by a threshold value). In a further example, seal 2253 can allow gas from driver back section 2270 to flow (i.e., backflow) into gas spring 2298 when the pressure in gas spring 2298 is less than the pressure in driver back section 2270 (e.g., less than or equal to a threshold value). To illustrate, in some such embodiments in which seal 2253 is configured to allow backflow, cylinder 2202 may not need to include low pressure port 2204. Make-up gas can enter the gas spring 2298 from the driver back section 2270 by flowing across the seal 2253 when the pressure in the driver back section 2270 is greater than the pressure in the gas spring 2298 (or greater than a threshold value).

[0104] FIG. 23 shows a cross-sectional side view of an exemplary gas spring system 2400 having a reservoir 2440, according to some embodiments of the present disclosure. FIG. 24 shows the exemplary gas spring system 2400 of FIG. 23 with a translator (e.g., including a piston 2450) in a second position, according to some embodiments of the present disclosure. Panel 2480 shows the piston 2450 when the translator is near BDC, and panel 2481 shows the piston 2450 when the translator is near TDC, indicating that the breathing port 2404 is open. In some embodiments, the gas spring system can include a reservoir configured to seal between the gas spring cylinder 2402 and the gas spring bearing housing 2412. In some embodiments, a seal can be included to seal against the cylinder, bearing housing, stator, structural frame, any other suitable component, or any combination thereof, which in turn seal against the bearing housing. For example, reservoir 2440 may be configured to seal against a stator (not shown) to react to axial loads and against bearing housing 2412 to reduce axial loads and provide radial compliance. In further examples, reservoir 2440 may be sealed against a structural frame (not shown), a flange (not shown) of cylinder 2402, or any other suitable component. As shown, reservoir 2440 has an associated volume (e.g., volume 2470). As shown, gas spring system 2400 includes a reservoir supply port 2443. For example, in some embodiments, ambient air (e.g., unconditioned from the environment, or optionally filtered, compressed, cooled, heated, or otherwise conditioned) is supplied via reservoir supply port 2443 (e.g., using a reed valve 2444 as shown).In illustrative examples, the reservoir 2440 can exhibit a breathing behavior (e.g., alternating flow of gas in and out) when gas is introduced into the reservoir 2440 through the reservoir supply port 2443 and then flows into the gas spring 2498 through the breathing port 2404. In some embodiments, as shown, the gas spring cylinder 2402 includes a high-pressure port 2405. For example, the high-pressure port 2405 can be coupled to a gas bearing system and configured to provide pressurized gas to one or more gas bearings of the gas bearing system. In some embodiments, when the piston seal 2453 opens the breathing port 2404, gas in the volume 2470 of the reservoir 2440 flows into the gas spring 2498 through the breathing port 2404 (e.g., to replenish gas lost through the high-pressure port 2405, gas leaking past the piston seal 2453, or both). In some such embodiments, the gas in the reservoir 2440 can be sized to build up pressure before flowing into the gas spring 2498 through the port 2404. In some embodiments, reservoir 2440 is sealed to bearing housing 2412 (e.g., by an O-ring, gasket, close tolerance, or other suitable seal), thus effectively forming a seal against translator tube 2452 against flow from reservoir 2440 (e.g., when the pressure in volume 2470 is lower than the gas bearing pressure). As piston 2450 translates (e.g., gas spring 2498 expands and contracts), the pressure in volume 2470 may change accordingly (e.g., generally with a pressure change opposite in sign to the change in pressure in gas spring 2498). The larger volume 2470, the smaller the change in pressure in volume 2470. For example, fluctuations in pressure in volume 2470 can be reduced by increasing volume 2470 (e.g., by increasing the size of reservoir 2440). Conversely, fluctuations in pressure in volume 2470 can be increased by decreasing volume 2470 (e.g., by decreasing the size of reservoir 2440).In some embodiments, reservoir 2440 is adjustable (e.g., volume 2470 is adjustable). For example, one or more tanks, bladders, or any other suitable components can be coupled to reservoir 2440 and can be opened, closed, or otherwise adjusted to adjust the total volume (e.g., volume 2470 plus additional volume). In some embodiments, reservoir 2440 is itself adjustable using any suitable mechanism, feature, or component. In some embodiments, reservoir 2440 is configured to seal against a structural frame (e.g., instead of bearing housing 2412).

[0105] In some embodiments, reservoir 2440 may be used to provide fuel compression. For example, natural gas or other suitable gas fuel may be supplied to volume 2270 and may be subjected to compression by the action of piston 2450, thus increasing the pressure of the fuel. In some embodiments, gas spring 2498 may be used to provide fuel compression. For example, fuel may be placed directly into gas spring 2498 (e.g., gas spring 2498 may comprise fuel), or compressed gas in gas spring 2498 may be used to compress the fuel (e.g., using high pressure port 2405 and a bladder or piston pump assembly).

[0106] FIG. 25 shows a cross-sectional side view of an exemplary gas spring system 2500 having a reservoir 2540 configured for intake compression, according to some embodiments of the present disclosure. As shown, the system of FIG. 25 is similar to the systems shown in FIGS. 22-24 , but with the addition of an intake supply valve 2542 disposed at an intake supply port 2541 and an optional intake supply tank 2544. As the piston 2550 and seal 2553 move along an axis 2570 within the cylinder 2502, the pressure within the reservoir volume 2570 may change. For example, as the gas spring 2598 expands, the pressure within the reservoir volume 2570 may increase, and as the gas spring 2598 contracts, the pressure within the reservoir volume 2570 may decrease. As shown, when the pressure in reservoir volume 2570 exceeds the cracking pressure of intake supply valve 2542, gas from reservoir volume 2570 flows through intake supply port 2541 to intake supply tank 2544 and then to the intake system. Thus, the driver back section (e.g., including reservoir volume 2570 and the volume between translator 2552 and cylinder 2502) can be used to provide intake gas (e.g., intake air for the reaction cylinder) or otherwise pressurize intake gas to increase boost pressure in the reaction cylinder (not shown in FIG. 25). In some embodiments, for example, the driver back section is used to pressurize intake gas to reduce or eliminate the need for an intake boost blower. In some embodiments, for example, the driver back section is used to pressurize intake gas in addition to the intake boost blower (e.g., gas from intake supply tank 2544 is provided to the boost blower of the intake system). In some embodiments, the reservoir 2540 can include one or more filters before or after the intake supply valve 2542, before or after the intake supply tank 2544, before the intake system, or combinations thereof.In the illustrative example, reservoir 2540 exhibits a breathing action when gas is introduced into reservoir 2540 via reservoir supply port 2543 (e.g., shown with supply port valve 2544), which then flows into gas spring 2598 via breathing port 2504 (e.g., which may be, but need not be, controlled by optional valve 2580), and out intake supply port 2541 into intake supply tank 2544. In some embodiments, it is not necessary to include an intake supply tank. For example, the volume of the duct from the intake supply port may include sufficient volume (e.g., to reduce pressure fluctuations from unsteady flow from valve opening and closing), and a separate tank may not be required.

[0107] FIG. 26 shows a side cross-sectional view of a portion of an exemplary gas spring system 2600 with a reservoir, according to some embodiments of the present disclosure. A translator 2620 is configured to move along the indicated axis. A bearing housing 2630 forms a bearing gap 2631 with a surface of the translator 2620 (e.g., to form a gas bearing). The translator 2620, including the seal 2621, and the cylinder 2602 define a gas spring 2697 (e.g., a sealed volume that functions as a spring). In some embodiments, the portion of the translator 2620 that defines the gas spring 2697 is a separate but attached piston assembly (shown in FIG. 26 as an integral part of the translator 2620) that includes the seal 2621. The gas spring port 2604 is configured to allow gas to enter the gas spring 2697 from a gas spring supply (e.g., which may include atmosphere, compressed air, or other suitable gas supply) when open (e.g., as shown, the seal 2621 opens the gas spring port 2604). Gas spring port 2604 may be open or valved (e.g., by one or more passive valves, one or more valves controlled by a control system, or any combination thereof). Reservoir 2640 seals against stator 2650, bearing housing 2630, and cylinder 2602 to define volume 2641, as shown. Reservoir port 2642 is configured to allow gas to enter volume 2641. Reservoir port 2643 is configured to allow gas to exit volume 2641. In some embodiments, reservoir ports 2642 and 2643 are each valved (e.g., by one or more passive valves, one or more valves controlled by a control system, or any combination thereof). For example, reservoir port 2643 may be configured to allow gas from volume 2641 to flow to an intake system (not shown), to provide boosted intake air to a gas spring inlet port (e.g., gas spring port 2604), or both.In some embodiments, it is not necessary to include reservoir port 2642 (inlet port), and only reservoir port 2643 (outlet port) may be included. For example, gas spring inlet port 2604 may provide make-up air to gas spring 2697 when gas spring inlet port 2604 is open to the gas spring (e.g., when seal 2621 is in a position near TDC as shown in FIG. 26 ), and may supply air to reservoir 2641 when gas spring inlet port 2604 is closed to the gas spring (and thus open to reservoir 2641). In some embodiments, it is not necessary to include reservoir port 2642 (inlet port), and it is not necessary to include reservoir port 2643 (outlet port).

[0108] FIG. 27 shows a side cross-sectional view of a portion of an exemplary gas spring system 2700 having a reservoir, according to some embodiments of the present disclosure. A translator 2720 is configured to move along the indicated axis. A bearing housing 2730 forms a bearing gap 2731 with a surface of the translator 2720 (e.g., to form a gas bearing). The translator 2720, including the seal 2721, and the cylinder 2702 define a gas spring 2797. In some embodiments, the portion of the translator 2720 that defines the gas spring 2797 is a separate but attached piston assembly (shown in FIG. 27 as an integral part of the translator 2720) that includes the seal 2721. The gas spring port 2704 is configured to allow gas to enter the gas spring 2797 from the volume 2741 when open (e.g., as shown, the seal 2721 opens the gas spring port 2704). The gas spring port 2704 may be open or valved (eg, by one or more passive valves, one or more valves controlled by a control system, or any combination thereof). Reservoir 2740 seals against stator 2750, bearing housing 2730, and cylinder 2702, as shown, to define volume 2741. Reservoir port 2742 is configured to allow gas to enter volume 2741. Reservoir port 2743 is configured to allow gas to exit volume 2741. In some embodiments, reservoir ports 2742 and 2743 are each valved (e.g., by one or more passive valves, one or more valves controlled by a control system, or any combination thereof). Gas spring system 2700 allows gas in volume 2741, which is compressed as translator 2720 moves from BDC toward TDC, to flow into gas spring port 2704 at high pressure when open. For example, reservoir port 2743 may be configured to allow gas from volume 2741 to flow to an intake system (not shown) to provide boosted intake air.

[0109] FIG. 28 shows a side cross-sectional view of a portion of an exemplary gas spring system 2800 having a reservoir, according to some embodiments of the present disclosure. A translator 2820 is configured to move along the indicated axis. A bearing housing 2830 forms a bearing gap 2831 with a surface of the translator 2820 (e.g., to form a gas bearing). The translator 2820, including the seal 2821, and the cylinder 2802 define a gas spring 2897. In some embodiments, the portion of the translator 2820 that defines the gas spring 2897 is a separate but attached piston assembly (shown in FIG. 28 as an integral part of the translator 2820) that includes the seal 2821. The gas spring port 2804 is configured to allow gas to enter the gas spring 2897 from the volume 2841 when open (e.g., as shown, the seal 2821 opens the gas spring port 2804). Gas spring port 2804 may be open or valved (e.g., by one or more passive valves, one or more valves controlled by a control system, or any combination thereof). Reservoir 2840 seals against stator 2850, bearing housing 2830, and cylinder 2802 to define volume 2841, as shown. Reservoir port 2842 is configured to allow gas to enter volume 2841. In some embodiments, reservoir port 2842 is valved (e.g., by one or more passive valves, one or more valves controlled by a control system, or any combination thereof).

[0110] In some embodiments, the flow of gas into and out of reservoir 2641, 2741, or 2841 is used to cool one or more components, such as, for example, the encoder readhead, the encoder strip / tape, any other suitable component, or any combination thereof. For example, the encoder readhead can be located on a gas spring cylinder or bearing housing that is at least partially contained within the reservoir, and the gas flow into and out of the reservoir can be used to cool the readhead. In another example, the encoder strip or tape can be located on a translator that moves at least partially within the reservoir, and the gas flow into and out of the reservoir can be used to cool the encoder strip or tape.

[0111] FIG. 29 shows a diagram of an exemplary gas spring system of an integrated linear generator system 2900, in accordance with some embodiments of the present disclosure. As shown, cylinder 2902 includes port 2962 (e.g., for receiving gas spring make-up gas) and port 2963 (e.g., for supplying gas for a gas bearing to a bearing housing 2916 of integrated linear generator system 2900). As shown, reservoir 2998 seals to cylinder 2902 using seal 2992 and to bearing housing 2916 using seal 2993. As shown, bearing housing 2916 is coupled to stator 2917 (e.g., using one or more mounts, flexures, or other components not shown). Piston 2911 with translator tube 2912 and seal 2979 is configured to move axially along gas spring cylinder 2902. As shown, piston 2911 can be positioned axially out of cylinder 2902 for maintenance, inspection, or repair. Hatch 2999 is removable, allowing access to piston 2911, seal 2979, and the end of translator tube 2912. For example, hatch 2999 can be attached (e.g., using fasteners, clamps, sliding joints, hinges, or any other attachment) to and sealed to reservoir 2998 during operation. Reservoir 2998 can include port 2967 for receiving make-up gas to supply port 2962.

[0112] FIG. 30 shows a side cross-sectional view of an exemplary gas spring cylinder assembly 3000 according to some embodiments of the present disclosure. The gas spring cylinder assembly 3000 includes a cylinder 3002, a head 3012, a spacer 3015, an energy absorber 3005, and a breathing port 3004. The cylinder 3002 includes a flange 3006 attached to the head 3012 by a fastener 3013. The spacer 3015 is axially disposed between the flange 3006 and the head 3012. The flange 3006, the spacer 3014, and the head 3012 have corresponding recesses for receiving a sliding bushing 3014 (e.g., as further described in the context of FIG. 31 ). The energy absorber 3005 is disposed radially inward of the cylinder 3002, as shown. When the translator 3020 moves sufficiently inward (e.g., toward the center of the corresponding generator assembly), it contacts and deforms an energy absorber 3005 configured to convert the translator's kinetic energy. The cylinder 3002 includes a flange 3030 for mounting to a frame system 3050 by a fastener 3031. In some embodiments, a spacer 3015 can be included to affect the compression ratio of the gas spring 3098. FIG. 31 shows a side cross-sectional view of an exemplary gas spring cylinder assembly 3000 opened using a sliding bushing 3014, according to some embodiments of the present disclosure. The sliding bushing 3014 allows the head 3012, the spacer 3015, or both, to be axially removed a distance from the flange 3006 (e.g., when the fastener 3013 is removed or otherwise loosened). In some embodiments, the distance is sufficient to allow removal, installation, and inspection of the piston 3021, the seal 3022, the tube 3023, any other suitable hardware, or any combination thereof. For example, the cylinder 3002 can be separated from the assembly position by any suitable length that is sufficient for inspection, maintenance, repair, or any combination thereof.In some embodiments, the spacer 3015 is configured to function as a ring compressor (eg, for ring removal, ring installation, ring replacement, ring inspection, or any combination thereof).

[0113] The bearing system is configured to constrain the translator's motion (primarily radially) while maintaining low frictional losses. The bearing system may include, for example, contact bearings, non-contact bearings, or a combination thereof, or any other suitable means for supporting translator motion while providing low friction. In some embodiments, the bearing system includes a gas bearing system configured to provide a layer of gas against the translator, e.g., to function as a gas bearing for frictionless, near-frictionless, or low-friction movement of the translator. For example, the gas bearing system may maintain a layer of pressurized gas between the translator and a bearing surface against which the translator moves.

[0114] 32 shows a system diagram of an exemplary bearing system 3200, according to some embodiments of the present disclosure. The bearing system may include, for example, one or more bearing housings (e.g., bearing housings 3212 and 3214), a regulator 3210, a tank 3208, an optional auxiliary bearing gas supply system 3250 with corresponding filters, a compressor, valves, piping, sensors, any other suitable components, or any suitable combination thereof.

[0115] The bearing housings 3212 and 3214 include bearing surfaces (e.g., which may be porous, include orifices, or both) configured to mate with, for example, gas bearings, which in turn mate with, the translator. In some embodiments, the bearing housings are mounted to the stator. Thus, in some such embodiments, alignment (e.g., lateral and axial alignment) of the bearing housing and the stator is maintained, thereby enabling linear motion of the translator along the axis of the linear generator. In some embodiments, the bearing housings include mechanisms for adjusting the alignment between the bearing housing and the translator, mechanisms for adjusting alignment between the bearing housings, or both. In some embodiments, the bearing housings can include mechanisms for automatically adjusting for expansion and contraction of the translator tube (e.g., due to thermal expansion or contraction, due to pressure). The bearing housings 3212 and 3214 are configured to supply bearing gas to the gas bearings, for example, via orifices (e.g., of any suitable cross-section) supplied from a common supply or multiple supplies, porous layers supplied from a common gas supply or multiple gas supplies, or a combination thereof. In some embodiments, the bearing housings 3212 and 3214 are configured to substantially azimuthally surround (e.g., not necessarily azimuthally continuous with) the corresponding translator. In some embodiments, the translator tubes may include bearing surfaces (e.g., polished or otherwise smooth surfaces) configured to mate with the gas bearings. In some embodiments, the inner surfaces of the bearing housings may be coated with a low-friction material (e.g., an abradable powder coating, a graphite-based coating, a ceramic-based coating) to minimize damage (e.g., scratches or galling) to the translator or bearing surfaces (e.g., bearing surfaces) when the surfaces come into contact.In some embodiments, the bearing housings 3212 and 3214 are configured to partially azimuthally surround the corresponding translator.

[0116] Optional tank 3208 is configured to provide an enclosed volume for accumulating bearing gas, thus reducing fluctuations in the bearing gas supply. In some embodiments, for example, tank 3208 is configured to receive bearing gas from a high-pressure port of the gas spring system (e.g., high-pressure port 2205 in FIG. 22 , high-pressure port 2405 in FIGS. 23-24 , or high-pressure port 2505 in FIG. 25 ), auxiliary system 3250, or both. In some embodiments, auxiliary system 3250 can supply all of the bearing gas to bearing housings 3212 and 3214. For example, during startup or shutdown or a maintenance event, auxiliary supply system 3250 may supply all of the bearing gas to the bearing housings (e.g., if the gas spring system is unable to provide the minimum required bearing gas flow or if the gas spring system is unable to provide bearing gas at or above the required pressure). Optional regulator 3210 functions as a pressure regulator to deliver bearing gas to bearing housings 3212 and 3214 at a constant or near-constant pressure. Regulator 3210 can include any suitable type of pressure regulator (e.g., active or passive), flow restrictor (e.g., orifice, passive valve, or controllable valve), any other suitable device, or any combination thereof. In some embodiments, a filter (not shown in FIG. 32) is included upstream or downstream of regulator 3210. In some embodiments, regulator 3210 may be controllable (e.g., manually or remotely) to adjust the pressure to bearing housings 3212 and 3214. In some embodiments, it is not necessary to include tank 3208, regulator 3210, or both, and bearing gas from a source may be delivered directly to bearing housings 3212 and 3214. Tank 3208 can include any suitable pressure vessel, such as, for example, a tank, pipe, box, plenum, or any other suitable component configured to reduce or limit fluctuations in gas pressure.In some embodiments, the tank 3208 can be implemented using a structural frame of the integrated linear generator system. For example, the structural frame can include hollow members (e.g., lateral members, end members, tubes, or other) configured to contain pressurized gas (e.g., bearing gas).

[0117] For example, air is a convenient bearing gas because it is abundant and generally readily available, but any suitable gas can be used as a bearing gas in accordance with the present disclosure. In some embodiments, the bearing gas is preferably sufficiently dry (e.g., non-condensing), sufficiently clean, and capable of being compressed to a pressure suitable for the desired gas bearing performance. The stiffness of the gas bearing may depend on the pressure of the gas bearing (e.g., a higher pressure gas bearing may have a higher stiffness up to the instability limit). In some embodiments, the bearing housings 3212 and 3214 may be configured to allow condensed liquid (e.g., water) to accumulate in the bearing housing, drain from the bearing housing, or both.

[0118] In some embodiments, the gas bearing system can be coupled to a high-pressure port of the gas spring system (e.g., high-pressure port 2205 in FIG. 22 , high-pressure port 2405 in FIGS. 23-24 , or high-pressure port 2505 in FIG. 25 ). For example, compressed gas from the gas spring can be extracted from the gas spring during high-pressure breathing, optionally conditioned, and used as bearing gas. In some embodiments, the high-pressure ports of one or more gas springs can be coupled to a reservoir, such as tank 3208, that can supply one or more gas bearings. In some embodiments, the high-pressure ports of one or more gas springs located on one or more linear generator systems within the same package can be coupled together via a common reservoir or other means and configured to supply gas to one or more gas bearings of one or more linear generator systems within the same package. In some such embodiments, an external gas compressor may not be required (but may optionally be included, e.g., particularly for startup), thus avoiding the need to include an additional mechanical system. In some embodiments, an external gas compressor is included and is used only during startup, shutdown, or maintenance of the linear generator assembly (e.g., when the pressure in the gas spring is insufficient to supply gas to the gas bearings). The tank 3208 is configured and sized to reduce pressure fluctuations of the gas from the high pressure port (e.g., via valve 2215 in FIG. 22), which may be pulsed due to the nature of the high pressure breathing process.

[0119] In some embodiments, the auxiliary system 3250 is configured to optionally supply bearing gas to the gas bearings. For example, in some embodiments, during startup of the linear generator, the gas spring system may not yet provide enough gas to function as a gas bearing (e.g., to have sufficient bearing stiffness), and the auxiliary system 3250 can be used to provide bearing gas at an appropriate pressure. In some such embodiments, once the gas spring system is able to provide sufficient bearing gas, the auxiliary system 3250 is deactivated; however, in some embodiments, the auxiliary system 3250 can remain in standby mode or continue to provide at least some bearing gas (e.g., supplementing the gas spring system). In a further example, the auxiliary system 3250 can be configured to provide bearing gas at an appropriate pressure and flow during maintenance events when the linear generator system is substantially turned off (e.g., not generating power).

[0120] Referring to FIG. 2 , bearing housings 216, 217, 226, and 227, or a subset thereof, may be supplied from a single bearing gas source, such as high-pressure ports 2305, 2405, or 2505, auxiliary system 2950, ​​or both, of FIGS. 23 , 24, and 25, respectively. In some embodiments, for example, any of bearing housings 216, 217, 226, and 227 of FIG. 2 may be supplied by either gas spring 298 or gas spring 299. In some embodiments, any gas spring disposed within a package may be supplied by any gas spring disposed within the same package, and the package may include one or more generator assemblies. FIG. 33 shows a cross-sectional view of generator assembly portion 3300 according to some embodiments of the present disclosure. Generator assembly portion 3300 includes a subassembly of an integrated linear generator system, including translator 3360, stator 3350, bearing housings 3302 and 3304, and gas bearings 3312 and 3314. The translator 3360 includes a tube 3362, which functions as a rigidly coupled piston and other components to form the rigid translator; a piston 3361 configured to contact the reaction section; a piston 3364 configured to contact the gas spring; and a section 3363 configured to electromagnetically interact with the stator 3350. Although discussed as a tube, the tube 3362 may have any suitable cross-sectional shape, and thus the gas bearings 3312 and 3314 may have a corresponding shape. For example, in some embodiments, the tube 3362 may have a rectangular cross-section, and thus the gas bearings 3312 and 3314 may be flat rather than annular. In some embodiments, the translator 3360 includes one or more tapered regions along at least a portion of its length. For example, the translator 3360 may be subject to high-temperature heat transfer from the reaction piston 3361. As a result of the high temperatures, the translator 3360 may experience thermal expansion that exceeds the maximum allowable air bearing clearance.In some embodiments, the translator 3360 can include one or more tapered sections to compensate for thermal expansion of the translator, allowing the translator and air bearing to function over a range of operating conditions.

[0121] Bearing housings 3302 and 3304 are configured to receive bearing gas from supply line(s) 3303 and 3305, respectively, to form respective gas bearings 3312 and 3314. For example, with reference to a tubular shape, each of bearing housings 3302 and 3304 can include a bearing surface disposed on a radially inwardly facing surface and configured to mate with respective annular gas bearings 3312 and 3314. Tube 3362 can include a cylindrical bearing surface configured to mate with annular gas bearings 3312 and 3314. During operation, gas bearings 3312 and 3314 enable translator 3360 to move along axis 3390 with low, near zero, or no friction and prevent substantial lateral (e.g., radial) movement away from axis 3390. For example, the gas bearings 3312 and 3314 can be configured to maintain a motor air gap 3316 between the stator 3350 (e.g., its iron and copper portions) and the section 3363 during operation. It will be understood that the gas bearings 3312 and 3314, as well as the motor air gap 3316, can have any suitable thickness. For example, it is generally preferable that the thickness be as thin as possible while ensuring reliable operation. The supply line(s) 3303 and 3305 can include one or more pipes, tubes, hoses, plenums, any other suitable conduits, any suitable fittings, or any combination thereof configured to deliver bearing gas to the bearing housings 3302 and 3304, respectively. For example, in some embodiments, the supply lines 3303 and 3305 can include flexible hoses or rigid tubes coupling a tank (e.g., tank 3208 in FIG. 32 ) to the respective bearing housings 3302 and 3304. In some embodiments, as shown, the bearing housings 3302 and 3304 include respective drain lines 3392 and 3394 configured to allow condensate removal based on gravity, pressure (e.g., via purging with pressurized bearing gas), or temperature (e.g., via evaporation of the condensate).The drain lines 3392 and 3394 can include, for example, valves, piping, hoses, tubing, fittings, sensors, condensate evaporation plates, and any other suitable components for removing condensate from the bearing housings, or any combination thereof. In some embodiments, the drain lines 3392 and 3394 can be located on the respective bearing housings 3302 and 3304 to allow condensate removal using gravity (e.g., located at or near the bearing housings to allow the condensed phase to flow out when a drain port is opened, with or without bearing gas pressure above atmospheric pressure). In some embodiments, the condensate from the drain lines 3392 and 3394 is removed from the linear generator assembly or a package enclosing the linear generator assembly, the vapor stator, or both in a liquid state. For example, the condensate from lines 3392 and 3394 can be transported as a liquid from the linear generator assembly or a package enclosing the linear generator assembly to the environment or a reservoir. In further examples, condensate from lines 3392 and 3394 may be transported from the linear generator assembly or the package enclosing the linear generator assembly as vapor (e.g., via evaporation) in the exhaust from the linear generator assembly or the package enclosing the linear generator assembly.

[0122] In some embodiments, one or both of the bearing housings 3302 and 3304 are rigidly attached to the stator 3350. For example, rigidly attaching the bearing housings 3302 and 3304 to the stator 3350 may help counter lateral (e.g., radial) loads on the translator 3360. In some embodiments, one or both of the bearing housings 3302 and 3304 may be attached to the stator 3350 via one or more flexures (e.g., with defined stiffness in one or more directions), fixtures, mounts, fasteners, any other suitable hardware, or any combination thereof. For example, the bearing housings may be attached to flexures, which are in turn coupled to the stator (e.g., by mounts), and the flexures may allow the bearing housings to pitch, yaw, or otherwise conform to the translator while maintaining alignment. In some embodiments, one or both of the bearing housings 3302 and 3304 need not be attached to the stator 3350, but may be attached to the driver cylinder, the reaction cylinder, any other suitable component of the linear generator system, or any combination thereof. In some embodiments, one or both of the bearing housings 3302 and 3304 may be attached to the stator 3350, the driver cylinder, the reaction cylinder, any other suitable component of the linear generator system, or any combination thereof.

[0123] To illustrate, the cantilever design of the translator / air bearing system minimizes constraints on the translator, making the product design and manufacture more tolerant to misalignment, for example. In some embodiments, one or both of the bearing housings 3302 and 3304 can be attached to the reaction cylinder or gas spring cylinder. In some embodiments, one or both of the bearing housings 3302 and 3304 can be attached to the external frame, housing, or block of the linear generator assembly.

[0124] In some embodiments, the bearing gas is configured to exit the bearing housings 3302 and 3304 (e.g., to form the respective gas bearings 3312 and 3314) in a substantially radially inward direction (i.e., with flow lines directed toward the axis 3390). The bearing gas can flow through porous sections of the bearing housings 3302 and 3304, ducts and orifices within the bearing housings 3302 and 3304, or a combination thereof, to reach the respective gas bearings 3312 and 3314. In some embodiments, the bearing housings 3302 and 3304 can include a coating, a wear layer, a dry film lubricant, or a combination thereof, on the corresponding bearing surfaces to accommodate contact with the translator 3360, for example. In some embodiments, the bearing housing extends azimuthally continuously (e.g., 360°) completely around the translator. In some embodiments, the bearing housing includes one or more bearing segments that extend an azimuth range around the translator. For example, the bearing housing can include four bearing segments spaced 90 degrees apart around the translator, with azimuthal gaps between the bearing segments. The bearing housing can include any suitable number of bearing segments with any suitable number of gaps and arranged in any suitable configuration around the translator.

[0125] In some embodiments, the translator 3360 can include one or more features that can engage with corresponding features on the stator 3350, the bearing housing 3302, the bearing housing 3304, or a combination thereof, to substantially lock the translator 3360 in place (e.g., axially, radially, azimuthally, or a combination thereof). For example, when not in operation (e.g., during maintenance, inspection, or repair), the translator 3360 can be positioned in an appropriate axial position relative to the stator 3350 and locked in place. The translator 3360 can include features (e.g., blind holes, through holes, notches, slots, pins, surfaces, any other suitable boss or recess features, or any combination thereof) that can be engaged by corresponding features to prevent the translator 3360 from moving in one or more directions. For example, the translator 3360 can include one or more blind holes configured to engage with one or more pins that prevent axial movement of the translator 3360. In further embodiments, the translator 3360 can include one or more notches configured to engage one or more pins that prevent axial movement of the translator 3360 .

[0126] 34 shows a cross-sectional view of an exemplary generator assembly portion 3400 according to some embodiments of the present disclosure. The generator assembly portion 3400 includes a subassembly of an integrated linear generator system, including a cylinder 3402 (e.g., a reaction cylinder), translators 3410 and 3420, stators 3417 and 3427, bearing housings 3416 and 3426, and seals 3415 and 3425. The translator 3410 includes, for example, a piston 3411 with seal 3479, a tube 3412, and a section 3413. The translator 3420 includes, for example, a piston 3421 with seal 3489, a tube 3422, and a section 3423.

[0127] For purposes of discussion, the generator assembly portion 3400 will be considered to use uniflow scavenging, with the intake and exhaust ports, both unvalved, on axially opposite sides of the cylinder 3402. Thus, for purposes of discussion, the translator 3410 will be considered to be an intake-side translator since the piston 3411 covers and opens the intake breathing port 3419. Additionally, for purposes of discussion, the translator 3420 will be considered to be an exhaust-side translator since the piston 3421 covers and opens the exhaust breathing port 3429. It will be understood that scavenging techniques other than uniflow scavenging may be used in accordance with the present disclosure.

[0128] Seals 3415 and 3425 provide a seal between cylinder 3402 and respective bearing housings 3416 and 3426. In some embodiments, seals 3415 and 3425 seal against cylinder 3402 (e.g., on the radially outer surface or the axially outer surface) and against any suitable surface of respective bearing housings 3416 and 3426. For example, volumes 3418 and 3428 behind respective pistons 3411 and 3421 (e.g., away from reaction section 3497) can contain intake gases and exhaust, respectively. In some situations, it is undesirable for reaction back section 3418 to be vented to atmosphere because the intake gases therein are at a boost pressure higher than atmospheric pressure, which could cause the intake gases to bleed out of bore 3403 of cylinder 3402 into atmosphere (e.g., resulting in possible fuel exhaust if the intake gases are premixed, thus wasting energy). Similarly, in some circumstances, it is undesirable for the reaction back section 3428 to be vented to the atmosphere because the exhaust gases therein are hot and could cause the performance of nearby components (e.g., the stator 3427 or other components) to be affected. Because the bearing housings 3416 and 3426 provide pressurized gas to their respective gas bearings, the corresponding bearing gas acts as an additional seal, preventing gas from the bore 3403 of the cylinder 3402 or gas from volumes 3418 and 3428 from passing through the corresponding gas bearing. For example, if the pressure of the intake gas bearing is greater than the pressure in the intake system or the pressure in volume 3418, the intake gas will be restricted or prevented from leaking to the surroundings (e.g., atmosphere). Similarly, if the pressure of the exhaust gas bearing is greater than the pressure in the exhaust system or the pressure in volume 3428, the exhaust gas in volume 3428 will be restricted or prevented from leaking to the surroundings (e.g., atmosphere).Seals 3415 and 3425 may include, for example, O-rings, crush seals, gaskets, flanges, threads, alignment features, mating tolerances (e.g., near-airtight mating joints), any other suitable components or features, or any combination thereof. Sections 3480 and 3481 provide expanded views in FIGS. 36 and 37. In some embodiments, seal 3415, seal 3425, or both, may be fully or partially integrated into cylinder 3402, the respective bearing housings 3416 and 3426, or a combination thereof. For example, seals 3415 and 3425 need not include rigid components or housing structures, but may include O-rings or gaskets between mating components. In some embodiments, seal 3415, seal 3425, or both, may be configured to indirectly seal against cylinder 3402. For example, the seals may seal against another component of the integrated linear generator system (e.g., an intake or exhaust manifold) that is sealed against cylinder 3402. In some embodiments, the generator assembly portion 3400 can include one or more ring compressors, as shown in Figure 2. For example, a respective ring compressor can be located at each axial end of the cylinder 3402 to interact with a respective seal 3479 and 3489.

[0129] FIG. 35 shows a cross-sectional view of a generator assembly portion 3500 according to some embodiments of the present disclosure. The generator assembly portion 3200 is similar to the generator assembly portion 3400 of FIG. 34 and includes an intake manifold 3598 but does not include the seal 3415. The intake manifold 3598 seals to the cylinder 3402 and bearing housing 3416 and functions as an intake manifold and a seal (e.g., similar in function to the seal 3415 of FIG. 34). An intake port 3419 is disposed within the intake manifold 3598, and intake gas flows from the intake manifold 3498 to the intake port 3419. The bearing gas, or a portion thereof, can flow from the bearing housing 3416 into the gas bearing and then into the intake manifold 3598. The intake manifold 3598 may, for example, be similar in shape and arrangement to the reservoir of FIGS. 23-29 arranged to contain gas in the back section (although, for example, port arrangement, volume, and / or other aspects may differ). In some embodiments, an exhaust manifold is included on the exhaust side of the generator assembly (e.g., similar to the intake manifold 3598 on the intake side). In some embodiments, the manifold may mate with the cylinder, bearing housing, or both.

[0130] FIG. 36 shows an enlarged view of section 3480 of FIG. 34 in which a seal 3479 is positioned axially in front of the intake port 3419 (e.g., the intake port is closed to the reaction section 3497), according to some embodiments of the present disclosure. Bearing gas in the gas bearing 3470 can flow in both axial directions while maintaining a bearing gap 3461 (e.g., the space between the bearing housing 3416 and the translator 3410) between the bearing housing 3416 and the translator 3410 (i.e., the gas bearing) purged with bearing gas. Thus, a mixture of intake gas (e.g., from the intake port) and bearing gas can reside behind the piston 3411 in the bore 3403 (e.g., in the reaction back section 3418), with only the bearing gas exiting near the stator 3417 (e.g., which may be open to the atmosphere). Thus, the bearing housing 3416 and seal 3415 act to seal the gas in the bore 3403 from the atmosphere surrounding the cylinder 3402. The seal 3479 seals the piston 3411 to the cylinder 3402 and is located forward of the intake port as shown in FIG. 34. The reaction back section 3418 extends from the bearing housing 3416 to the seal 3479 and is bounded by the seal 3415 and the cylinder 3402. As the translator 3410 translates axially, the volume of the reaction back section 3418 changes and may be subject to boundary actions (e.g., compression and expansion) accordingly. Gases within the reaction back section 3418 may include a mixture of bearing gases and intake gases (e.g., along with gases from blowback and blow-by) that may flow from the reaction back section 3418 into the port 3419 when the seal 3479 is forward of the port 3419 (e.g., flow through the port 3418 may be unsteady). For example, in some embodiments, the bearing gas is air, and any bearing gas that mixes with the intake gas in the reaction back section 3418 is included in the intake gas that undergoes reaction in the bore 3403.In the exemplary embodiment, approximately half of the bearing gas flowing into bearing gap 3461 flows into reaction back section 3418 and may undergo reactions in reaction section 3497. If air is the bearing gas, any air from bearing gap 3461 entering reaction section 3497 biases the intake gas mixture provided to intake port 3419 from the intake system. To explain, a measurement of exhaust gas composition from the linear generator may represent both the intake gas composition and the bearing gas composition. The pressure in reaction back section 3418 is lower than the pressure of the bearing gas in bearing gap 3461, resulting in at least some bearing gas flowing from bearing housing 3416 to reaction back section 3418.

[0131] FIG. 37 shows an expanded view of section 3481 of FIG. 34, with seal 3419 positioned axially after the intake port (e.g., the intake port is open to reaction section 3497), according to some embodiments of the present disclosure. Sections 3481 and 3480 are identical except for the axial position of the translator 3410. In some embodiments, seal 3415 can be sized to affect this boundary effect. For example, in some embodiments, seal 3415 is configured so that when the breathing port is open (e.g., as shown in FIG. 37), the gas pressure in reaction back section 3418 is lower than the gas pressure of the gas bearing (e.g., to ensure sufficient flow of bearing gas). The reaction back section 3418 may exhibit a maximum pressure when the volume of the reaction back section 3418 is smallest (e.g., at or near the BDC position of the translator 3410), as exemplarily shown in FIG. 37.

[0132] To illustrate, for a given operating condition, the larger the volume of the reaction back section 3418 at BDC, the lower the volumetric compression and expansion ratios of the reaction back section 3418 during operation, and therefore the lower the maximum gas pressure in the reaction back section 3418. In some embodiments, the volume of the reaction back section 3418 is large enough to ensure that the pressure in the reaction back section 3418 is lower than the bearing gas pressure, while achieving the lowest possible pressure (e.g., minimizing boundary effects). For example, to illustrate, the peak pressure in the reaction back section 3418 can be kept low (e.g., less than 3 bar) and the variation over the stroke of the piston 3411 can be kept relatively low (e.g., a pressure ratio of less than 3:1 between maximum and minimum pressures). In some embodiments, the pressure in the reaction back section 3418 is kept below 2 bar with an intake gas pressure (e.g., boost pressure) of 1.2 bar. In some embodiments, the gas bearing operates with a bearing gas supply pressure of 6-10 bar, with the ultimate goal of achieving a pressure of 3-4 bar in the bearing gap 3461. The properties of the gas in the reaction back section 3418 can be influenced by the spatial dimensions of the translator 3410, piston 3411, cylinder 3402, seal 3415, bearing housing 3416, or their relative dimensions (e.g., their gaps or clearances), as well as the location of the seal 3479 and the location of the translator 3410 (e.g., TDC and BDC locations). While FIG. 37 is shown with respect to the intake side, the same mechanism can be utilized on the exhaust side.

[0133] FIG. 38 shows an enlarged cross-sectional view of an exemplary generator assembly portion, according to some embodiments of the present disclosure. The gas bearing is formed by providing a flow of bearing gas in a bearing gap 3871 between the bearing housing 3826 and the translator 3820, which is purged with bearing gas (i.e., a gas bearing). Thus, a mixture of exhaust gas and bearing gas can exist behind the piston 3821 in the bore 3803, with only the bearing gas exiting near the stator 3827 (e.g., which may be open to the atmosphere). The seal 3825 acts to seal the gas in the bore 3803 from the atmosphere. The seal 3825 is fixed against movement of the translator 3820 and is mounted to a seal holder 3875. While the seal 3825 is shown attached to the holder 3875, it could be mounted to the cylinder 3802, the ring compressor 3876, any other suitable component, or any suitable combination. A seal 3889 (e.g., a sealing ring assembly) moves with the seal to seal the piston 3821 to the cylinder 3802. The reaction back section 3828 extends from the seal 3825 to the seal 3889 and is bounded by the ring compressor 3876 and the cylinder 3802. As the translator 3820 translates axially, the volume of the reaction back section 3828 changes and may be subject to boundary actions (e.g., compression and expansion) accordingly. The gas within the reaction back section 3828 may include a mixture of bearing gas and exhaust gas, which may enter and exit the reaction back section 3828 and the port 3829 if the seal 3889 is in front of the port 3829 (e.g., flow through the port 3829 may be unstable). For example, in some embodiments, the bearing gas is air, and any bearing gas that mixes with the exhaust gas in the reaction back section 3828 is included in the gas that is vented to the exhaust system and ultimately to the atmosphere. In an exemplary embodiment, approximately half of the bearing gas flowing into bearing gap 3871 may flow into reaction back section 3828 .To illustrate, measurements of exhaust gas composition from the linear generator can represent both the intake gas composition and the bearing gas composition from the intake and exhaust bearings. The pressure in the reaction back section 3828 is lower than the pressure of the bearing gas in the bearing gap 3871, resulting in at least some bearing gas flowing from the bearing housing 3826 to the reaction back section 3828. To maintain bearing functionality, it may be important to maintain the pressure in the back section 3828 below the bearing supply pressure. If this is important, exposure to the exhaust manifold 3879 and gas exchange between the back section 3838 can avoid overpressurizing the back section. In this embodiment, port 3877 couples the reaction back section 3828 to the exhaust manifold 3879 to limit pressure buildup in the reaction back section 3828 (e.g., when the piston 3821 and seal 3889 are moving axially outward toward BDC). Seal 3899 seals between the outer surface of the cylinder 3802 and the manifold 3879, as shown. In some embodiments, this can be achieved by a port length that is long enough axially so that when the piston 3821 is at BDC, the back section 3838 is still able to exchange gas with the ports and exhaust manifold 3879. In some embodiments, overpressurization of the back section 3828 can be avoided by a check valve.

[0134] The ring compressor 3876 is configured to restrain the seal 3889 from repositioning or disassembly during maintenance. For example, the seal 3889 can be axially disposed within the ring compressor 3876, which can move axially and / or radially during maintenance, inspection, installation, removal, replacement, or any other suitable activity that occurs during other non-operational periods. The spring 3878 is configured to apply an axial force to the ring compressor 3876 (via the holder 3875 in FIG. 38 ) so that the ring compressor 3876 remains in contact with the cylinder 3802. As shown, the spring 3878 presses against the bearing housing 3826, although the spring 3878 can press against any suitable component. In some embodiments, the spring 3878 is integrated with the spring compressor 3876 and / or the holder 3875 as a single component or a single assembly. In some embodiments, the ring compressor 3876 is mechanically attached to the cylinder using, for example, a V-band, a clamp, a bolt, a screw, or any other suitable mechanical attachment method, or any combination. In some embodiments, the seal 3825, holder 3875, ring compressor 3876, and spring 3878 may be integrated as one piece (as shown in FIG. 38), multiple pieces, or separate pieces.

[0135] FIG. 39A shows a cross-sectional view of an example generator assembly portion 3900 with a seal 3989 in a ring compressor 3975, according to some embodiments of the present disclosure. In some embodiments, the seal (e.g., not shown, but similar to seal 3825 and seal holder 3875 of FIG. 38) can be removed (e.g., during maintenance and inspection) in the configuration shown in FIG. 39A. A bearing gap 3971 is disposed between a bearing housing 3926 (e.g., which can be mounted to a stator 3927) and a translator 3920 (i.e., a gas bearing) and can be purged with bearing gas. A seal 3989 (e.g., a sealing ring assembly) seals the piston 3921 to the bore 3903 of the cylinder 3902 and is disposed outside the exhaust port 3929, as shown in FIG. 39A. A seal 3999 seals between the outer surface of the cylinder 3902 and the manifold 3979, as shown.

[0136] The ring compressor 3976 is configured to restrain the seal 3989 from being repositioned or disassembled during maintenance. For example, as shown, the seal 3989 is axially disposed within the ring compressor 3976 (e.g., during maintenance, inspection, installation, removal, replacement, or any other suitable activity that occurs during other non-operational periods). As shown, the seal 3989 includes a multi-part seal that forms a sealing ring assembly (e.g., to accommodate wear of the seal 3989). In some exemplary embodiments, the ring compressor 3976 includes a clamshell structure that can be opened to provide access to the seal 3989. In other exemplary embodiments, the ring compressor 3976 can be comprised of a single piece and can be moved axially out of the way to provide access to the seal 3989.

[0137] 39B shows a cross-sectional view of the example generator assembly portion 3900 of FIG. 39A with the ring compressor 3976 removed axially outward from the seal 3989, according to some embodiments of the present disclosure. As shown, the ring compressor 3976 is moved radially outward, the seal 3989 is partially disassembled, and segments are removed from the piston 3921. For example, the configuration shown in FIG. 39B may correspond to a time between inspection or replacement of the seal 3989, inspection of the lands or ring grooves of the piston 3921, or other suitable time outside of operation of the generator assembly. In some embodiments, the ring compressor 3976 is configured to move radially outward, axially outward, or both to remove ring segments.

[0138] In some embodiments, the seal and bearing housing of Figures 34-39 may be used with a gas spring piston and cylinder. For example, as discussed in the context of Figures 22-29, a reservoir may act as a seal between the cylinder and bearing housing. In some embodiments, the seal (e.g., seal 34115, seal 3425, or both), intake manifold 3298 may mate or otherwise seal against a stator (e.g., stator 3417, stator 3427), similar to the arrangements shown in Figures 26-28.

[0139] In some embodiments, the translator 3920 can include one or more features (not shown) that can engage with corresponding features of the generator assembly to substantially lock the translator 3920 in a predetermined position (e.g., axially, radially, azimuthally, or a combination thereof). For example, in the configuration of FIG. 39B , the translator 3920 can be positioned at an appropriate axial location on the generator assembly (e.g., relative to the stator 3927, bearing housing 3926, cylinder 3902, or features thereof) and locked in place. The translator 3920 can include features (e.g., blind holes, through-holes, notches, slots, pins, surfaces, any other suitable boss or recess features, or any combination thereof) that can be engaged by corresponding features to prevent the translator 3920 from moving in one or more directions. For example, the translator 3920 can include one or more blind holes configured to engage with one or more pins that prevent axial movement of the translator 3920. In further embodiments, the translator 3920 can include one or more notches configured to engage one or more pins that prevent axial movement of the translator 3920 .

[0140] FIG. 40 shows a cross-sectional view of a generator assembly portion 4000 having a seal 4061, according to some embodiments of the present disclosure. The generator assembly portion 4000 may be similar to, for example, one side of the generator assembly portion 3400 of FIG. 34 . The generator assembly portion 4000 includes a manifold 4098 and a seal 4061 that seals between the cylinder 4002 and the bearing housing 4016, as shown. Alternatively, the seal may be configured to seal between the manifold 4098 and the bearing housing 4016 (e.g., as shown by seal 4062). The manifold 4098 seals to the cylinder 4002 (e.g., using seal 4062) and either directs intake gases to a port 4019 or directs exhaust gases from the port 4019 (e.g., depending on which side of the generator assembly manifold 4098 it is mounted on). The port 4019 is located at the cylinder 4002 within the manifold 4098. The bearing gas, or a portion thereof, can flow from the bearing housing 4016 to the gas bearing and then to the manifold 4098. The manifold 4098 can be similar in shape and arrangement to the reservoirs of FIGS. 23-28 arranged to contain gas in the back section (although, for example, the port arrangement, volume, and / or other aspects can differ). In some embodiments, the seal 4061 includes a hatch 4099 that can be removable. For example, the hatch 4099 allows for maintenance of the piston 4011, the seal 4079, or the end of the tube 4012.

[0141] FIG. 41 shows a cross-sectional view of a generator assembly portion 4100 having an intake manifold that seals against a bearing housing, according to some embodiments of the present disclosure. The generator assembly portion 4100 may be similar to, for example, one side of the generator assembly portion 3400 of FIG. 34. The generator assembly portion 4100 includes a manifold 4198 that seals between a cylinder 4102 and a bearing housing 4116, as shown. The manifold 4198 seals to the cylinder 4102 using a seal 4162 and to the bearing housing 4116 using a seal 4161, and directs intake gases to a port 4119 or exhaust, or directs exhaust gases from the port 4119 (e.g., depending on which side of the generator assembly manifold 4198 it is mounted on). The port 4119 is located at the cylinder 4102 within the manifold 4198. The bearing gas, or a portion thereof, can flow from the bearing housing 4116 to the gas bearing and then to the manifold 4198. The manifold 4198 may be similar in shape and configuration to the reservoirs of FIGS. 23-29 arranged to contain gas in the back section (although, for example, the port configuration, volume, and / or other aspects may differ). In some embodiments, the manifold 4198 includes a hatch 4199 that may be removable. For example, the hatch 4199 allows for maintenance of the piston 4111, the seal 4179, or the end of the tube 4112.

[0142] A translation assembly or "translator" is an actuator that couples the expansion and compression of a gas volume to electromagnetic interaction with a stator to generate electrical power. The translator therefore moves under pressure and electromagnetic force, generates an electromotive force (emf) in phase with the stator (e.g., reacts inversely to the emf generated by the stator), achieves a nominally linear path of travel, and can withstand thermal and mechanical loads encountered during an operating cycle.

[0143] FIG. 42 shows a side view of an exemplary translator 4200 according to some embodiments of the present disclosure. FIG. 43 shows an axial end view of the translator 4200 according to some embodiments of the present disclosure. The axial end view in FIG. 43 is taken from direction 4201. The translator 4200 includes a tube 4212 to which pistons 4211 and 4214 are rigidly coupled (e.g., bolted, screwed, clamped, or welded). The translator 4200 includes a section 4213 that can include features (e.g., magnets) to enable desired electromagnetic interaction with the stator. In some embodiments, as shown, the translator 4200 also optionally includes rails 4215 and 4216, each configured to provide a position index, an anti-clocking bearing surface, or both. In some embodiments, the translator 4200 does not include rails, and sufficient anti-clocking stiffness in the azimuthal direction is provided via electromagnetic interaction between the stator and the translator (e.g., as described in the context of FIG. 49). In some embodiments, the translator 4200 or components thereof can be symmetrical about the axis 4290 (e.g., including circular shapes, fastener patterns, rail arrangements, and other aspects having rotational symmetry about the axis 4290). In some embodiments, the translator 4200 or components thereof need not be symmetrical about the axis 4290. In some embodiments, the section 4213, the piston 4211, and the piston 4214 can have substantially the same diameter as the tube 4212. In some embodiments, the section 4213, the piston 4211, and the piston 4214 can have different diameters, both smaller and larger than the tube 4212. As shown, the translator 4200 includes two pistons 4211 and 4214. In some embodiments, the piston 4214 is configured to contact a driver section, such as the gas spring 2298 in FIG. 22. While shown in FIG. 42 as being located at the same axial location, in some embodiments, the rails are included in more than one axial location or region.Pistons 4211 and 4214 may be, but need not be, identical. For example, pistons 4211 and 4214 may differ in size (e.g., diameter, axial length), mechanism, number of seals (e.g., one ring or multiple rings), or attachment (e.g., different fasteners or fastener orientation). In a further example, piston 4211 may be positioned to contact the reaction section and thus configured to accommodate higher temperatures, greater heat fluxes, or both than piston 4214. As shown, translator 4200 does not include bearing housings, gas passages to feed the gas bearings, or bearing components (e.g., gas bearings) other than surfaces configured to interface with the bearings.

[0144] Rail 4215 includes surface 4230, which can include, for example, features for position indication or indexing, and surfaces 4231 and 4232, which can include anti-clocking bearing surfaces. Anti-clocking bearing surfaces 4231 and 4232 can receive forces in the azimuthal direction (e.g., their faces are perpendicular or nearly perpendicular to the azimuthal direction). Rail 4216 includes, for example, surface 4240, which can include features for position indication or indexing, and surfaces 4241 and 4242, which can include anti-clocking bearing surfaces. In some embodiments, the translator can include zero, one, two, or more rails with any suitable azimuthal or axial positioning about the translator in accordance with this disclosure. For example, in some embodiments, the translator can include two or more rails to provide multiple position indications (e.g., for redundancy, precision, symmetry, or a combination thereof). In some embodiments, translator 4200 need not include anti-clocking rails or anti-clocking features. In some embodiments, without anticlocking rails, magnetic interaction between the translator and stator can provide adequate anticlocking stiffness in the azimuthal direction. In some embodiments, for example, without anticlocking rails 4215 and 4216, a position indexing mechanism can be mounted or directly integrated into translator 4200 (e.g., mounted or directly integrated into tube 4212). In some embodiments, without anticlocking rails 4215 and 4216, for example, position can be determined by electromagnetic interaction between the stator and section 4213. In some embodiments, surfaces 4231, 4232, 4241, and 4242 are configured to mate with corresponding anticlocking bearings (e.g., which may include anticlocking gas bearings). The anticlocking bearings provide stiffness in the azimuthal direction, thereby preventing or reducing azimuthal movement of the translator.In some embodiments, surface 4230 or 4240 may include machined features for position indication or indexing, magnetic tape for position indication or indexing, optical or electrical position sensors, any other suitable features for position indication or indexing, or any combination thereof. In some embodiments, sensing the position of the translator relative to the stator may be determined without the use of an external position indexing mechanism by sensing the position of one or more rows of magnetic features in section 4213 of the translator. For example, back electromotive force (emf) may be measured in one or more phase windings to determine the relative position of the stator and translator. In further examples, control signals (e.g., pulse-width modulated signals for applying current), measured currents, or both may be used to determine the relative position of the stator and translator.

[0145] In some embodiments, the translator 4200 can include one or more features that can engage with corresponding features of the generator assembly to substantially lock the translator 4200 in a predetermined position (e.g., axially, radially, azimuthally, or a combination thereof). For example, when not in operation (e.g., during maintenance, inspection, or repair), the translator 4200 can be positioned in an appropriate axial position on the generator assembly (e.g., relative to the stator, bearing housing, cylinder, or features thereof) and locked in place. The translator 4200 can include features (e.g., blind holes, through holes, notches, slots, pins, surfaces, any other suitable boss or recess features, or any combination thereof) that can be engaged by corresponding features to prevent the translator 4200 from moving in one or more directions. For example, the translator 4200 can include one or more blind holes configured to engage with one or more pins that prevent axial movement of the translator 4200. In further embodiments, the translator 4200 can include one or more notches configured to engage one or more pins that prevent axial movement of the translator 4200 .

[0146] FIG. 44 shows a side cross-sectional view of an exemplary translator 4400 having a tapered region 4402 and an optional spacer 4470, according to some embodiments of the present disclosure. As shown, the end 4450 shown is coupled to a spacer 4470, which is coupled to a piston 4460 (e.g., having a seal 4461). Because the piston 4460 may contact relatively hot gases (e.g., from compression and / or chemical reactions), the bearing surface 4410 may exhibit a non-uniform axial temperature field, which may cause radially non-uniform thermal expansion. In some embodiments, the translator tube 4401 may include a tapered region configured to allow for non-uniform radial expansion to maintain a desired bearing clearance (e.g., gas bearing thickness). For example, the tapered region 4402 is axially disposed between a portion of the translator tube having a first outer diameter (OD1) 4411 and a second portion of the translator tube having a second outer diameter (OD2, larger than OD1) 4413. To illustrate, during operation, heat transfer from the power cylinder piston (e.g., reaction section piston), heat transfer from exposure to compressed gas and post-reaction gas, or both, may be reduced to the translator tube by spacer 4470 (e.g., which may include a thermal conductivity lower than that of piston 4460 or translator tube 4401). In some circumstances (e.g., without a tapered region), the magnitude of thermal expansion may cause the diameter to be larger than the maximum allowable diameter while maintaining sufficient gas bearing clearance. Tapered region 4402 of translator 4400 compensates for this thermal expansion, thereby allowing the gas bearing to function over a range of operating conditions (e.g., the axial temperature profile of the translator tube). Tapered region 4402 may include any suitable geometric profile, such as, for example, a straight transition (e.g., conical), a piecewise linear transition (e.g., compound conical), a curved transition (e.g., any suitable curvature, continuous or piecewise), other suitable transition, or any combination or compound transition thereof.In some embodiments, the translator 4400 need not include a spacer 4470, and the piston 4461 can be attached to the translator tube 4401. In some embodiments, the piston can include at least two separate components, the piston section 4460, and an optional collar section (not shown), which may be made of different materials with different material properties, including heat capacity, etc. In an exemplary embodiment, the piston collar helps to further isolate the translator 4401 from the high temperatures of the piston 4460.

[0147] According to some embodiments of the present disclosure, a low thermal conductivity material may be inserted between the end face of the translator tube 4401 and the piston 4460. For example, the low thermal conductivity material may be a ceramic or metallic sheet or ring (e.g., similar to a gasket). This material is configured to support a compressive load (e.g., during operation) but is insulating (e.g., to reduce heat transfer). The insulating material may include any suitable material, such as, for example, a ceramic material or a metal. In some embodiments, the length of the piston (e.g., made of a more heat-resistant material) is relatively long, further separating the axial end face of the translator tube from the heat of the reaction section of the cylinder.

[0148] For example, inclusion of a recess in one or the other mating surface can form a pocket to help reduce heat transfer. The recess can be cut, punched, pressed, machined, or otherwise formed in the piston, the translator tube, or both. In a further example, a layer of insulating material can be inserted at the mating surface to reduce heat transfer. The insulating material can include, for example, ceramic (e.g., woven or fibrous ceramic cloth or gasket). In some embodiments, all or a portion of the piston comprises a more heat-resistant material (e.g., Inconel or ceramic). In some embodiments, increasing the axial length of the piston moves the end face of the translator tube further away from the reaction section of the cylinder, resulting in reduced heat transfer to the translator. It will be understood that the joint between the piston and translator tube can correspond to a reaction section piston, a driver section piston, or any other suitable piston for which reduced heat transfer is desired.

[0149] To illustrate, during operation, heat transfer from the power cylinder piston (e.g., reaction section piston), heat transfer from exposure to compressed gas and post-reaction gas, or both, may be reduced to the translator tube by spacer 4470 (e.g., which may include a thermal conductivity lower than that of piston 4460 or translator tube 4401). In some circumstances (e.g., without a tapered region), the magnitude of thermal expansion may cause the diameter to be larger than the maximum allowable diameter while maintaining sufficient gas bearing clearance. Tapered region 4402 of translator 4400 compensates for this thermal expansion, thereby allowing the gas bearing to function over a range of operating conditions (e.g., the axial temperature profile of the translator tube). Tapered region 4402 may include any suitable geometric profile, such as, for example, a straight transition (e.g., a regular cone), a piecewise linear transition (e.g., a compound cone), a curved transition (e.g., any suitable curvature, continuous or piecewise), other suitable transitions, or any combination or compound transition thereof.

[0150] In some embodiments, as shown, the translator 4400 includes a pocket 4471 or other recessed feature according to some embodiments of the present disclosure. The piston 4460 includes one or more pockets 4471 azimuthally arranged around its mating surface to the spacer 4470 (or, for example, the mating surface of the translator tube 4401 if a spacer is not included), as shown. The pocket 4471 reduces the contact area between the end face of the spacer 4470 or translator tube 4401 and the mating surface of the piston 4460. A recess such as the pocket 4471 can be any suitable shape, such as, for example, a pocket, groove, blind hole, slot, or other suitable shape configured to reduce the contact area while still distributing compressive loads at the mating surface. In some embodiments, the spacer 4470, the translator tube 4401, or both, include a recessed feature. For example, the spacer 4470, the translator tube 4401, or both, can include a continuous groove that reduces the contact area between the end face of the translator tube 4401 and the mating surface of the piston 4460. The grooves may include any suitable cross-sectional shape, such as, for example, square, circular, triangular, trapezoidal, compound, or other suitable shape, etc. In some embodiments, the grooves need not be continuous but may be divided or include pockets.

[0151] In some embodiments, cooling air is directed to the translator to cool one or more surfaces or components (e.g., 2628 in FIG. 2 or 3898 in FIG. 38). For example, a plenum can direct cooling air to a bearing surface to cool the bearing surface and reduce thermal deformation or expansion.

[0152] In some embodiments, the piston may include a mechanism or component to reduce, restrict, disperse, or otherwise control the adverse effects of blow-by gases downstream of the seal (e.g., into the translator tube). An example of this is shown in FIG. 44 along with a spacer 4470. In some embodiments, the piston 4460 may include or be configured with the mechanism shown in FIG. 6. In some embodiments, as shown, [insert description of FIG. 6 based on slide]

[0153] FIG. 45 shows a side cross-sectional view of an example translator tube 4510 end and a rail 4512 with a cantilever cross-section, according to some embodiments of the present disclosure. For example, the rail can be configured to constrain rotational motion of the translator and / or mount an encoder tape for position measurement. In some embodiments, the rail may be comparable in thickness to the translator tube, so the rail may be able to increase the local stiffness of the translator tube (e.g., at least where the rail is attached). In some embodiments, if the rail were rigidly coupled to the translator tube along its entire length, the rail may experience relatively large local stresses at the end of the rail (thus, for example, resulting in deformation of the bearing surface). In some embodiments, the rail is attached to the translator only along a portion of the rail, and the cantilevered portion of the rail is not attached to the tube. Thus, the rail with the cantilevered portion may contribute less to the stiffness of the translator assembly and may cause less deformation. For example, under compressive loads (e.g., caused by high pressure acting on the translator tube), the increased stiffness provided by a fully attached rail can result in localized deformation of the out-of-round shape that is incompatible with gas bearing operation. In some embodiments, the portion of the bearing surface most affected by this deformation can be decoupled from the rail stiffness by cantilevering a portion of the rail. The translator tube 4510 in FIG. 45 is coupled to a rail 4512 having an attached portion 4504 and a cantilever portion 4502. The translator tube 4510 experiences less localized stress than a translator tube with a fully attached rail without the cantilever portion 4502. A piston 4560 is shown attached to the translator tube 4510 for reference.

[0154] 46 shows a perspective view of an end of an exemplary translator tube 4601 coupled to a piston 4650 via a fastener 4605, according to some embodiments of the present disclosure. The translator tube 4601 is sealed to the piston 4650 using a seal 4602 (e.g., an O-ring, gasket, or other sealing material). As shown, the fastener 4605 is oriented to extend axially through the piston 4650 from the piston face 4651 to the axial end of the translator tube 4601. In some embodiments, the piston 4650 can be, for example, a gas spring piston.

[0155] 47 shows a perspective view of an end of an exemplary translator tube 4701 coupled to a piston 4750 via an obliquely oriented fastener 4705, according to some embodiments of the present disclosure. The translator tube 4701 is sealed to the piston 4750. In some embodiments, a pocket 4707 is included in the piston 4750 (e.g., as shown), the translator tube 4701, or both. As shown, the fastener 4705 is oriented at an oblique angle (e.g., relative to the axial direction) and extends through the side of the translator tube 4701 into the piston 4750. In some embodiments, the piston 4750 can be, for example, a reaction section piston. For example, because the fastener 4705 engages the backside of the piston 4750 (e.g., away from the piston face 4708), less clearance volume is formed, which may reduce heat transfer, reaction quenching, or both.

[0156] An obliquely oriented fastener is oriented at a non-zero angle relative to the axial direction (e.g., not parallel or perpendicular to the axial direction). In some embodiments, an obliquely oriented fastener allows for a relatively short piston in the axial direction (e.g., the piston does not need to correspond to the entire length of the fastener, but only the protruding length). In some embodiments, an obliquely oriented fastener allows for a relatively short piston length while using a fastener of a desired length (e.g., for a desired bolt tension / elongation when torqued), which allows for a shorter translator, a shorter total generator assembly length, or both.

[0157] In some embodiments, fasteners (e.g., diagonally oriented fasteners) may be positioned diametrically opposed (e.g., radially opposed). For example, in some such embodiments, the radial tension contribution from each fastener is balanced by the opposing fastener, thus resulting in only a net axial clamping load. In some embodiments, the use of opposing diagonally oriented fasteners 4430 enables sufficient axial clamping load on the piston joint with minimal length and mass. The piston can be attached to the translator tube using any suitable number of fasteners, in any suitable arrangement, and oriented at any suitable angle. For example, the fasteners (e.g., diagonally oriented fasteners) can be equally spaced azimuthally around the piston. In a further example, the diagonally oriented fasteners can be grouped, with the groupings spaced around the piston. In some embodiments, fasteners oriented parallel or perpendicular to the translator axis can be used. In some embodiments, fasteners with different orientations or uneven spacing can be used.

[0158] In some embodiments, the axial length of the piston may be selected to reduce or otherwise limit heat transfer from the piston surface to the bearing surface of the translator.

[0159] 48 shows an end view of a translator 4800 and additional components according to some embodiments of the present disclosure. The translator 4800 includes a rail 4816 rigidly attached at least partially to a translator tube of the translator 4800. Bearing gaps 4845 and 4846 are disposed between the rail 4816 and bearing housings 4841 and 4842, respectively. The bearing gaps 4845 and 4846 are configured to be filled with a bearing gas having a pressure suitable to function as gas bearings for maintaining or otherwise constraining the azimuthal position of the translator 4800 (e.g., during operation or other processes).

[0160] Bearing housings 4841 and 4842 are configured to mate with corresponding gas bearings, which in turn mate with corresponding surfaces of rail 4816. In some embodiments, bearing housings 4841 and 4842 are stationary relative to translator 4800. For example, bearing housings 4841 and 4842 can be rigidly mounted (e.g., fixed), flexibly mounted (e.g., mounted via flexures), or integrated (e.g., as a single piece) to a stator, which is a bearing housing for constraining lateral movement of the translator, a bearing housing for constraining lateral movement of the translator (e.g., bearing housings 3302 and 3304 of FIG. 33), a frame system, any other suitable mounting component, or any combination thereof. In some embodiments, bearing housings 4841 and 4842 are configured to create corresponding gas bearings that provide azimuthal stiffness to the orientation of translator 4800 (e.g., against azimuthal rotation of translator 4800, and thus providing azimuthal anticlocking). As shown, supply lines 4871 and 4872 are configured to supply bearing gas (e.g., pressurized bearing gas supplied from a compressor or gas spring at above 1 atmosphere) to respective bearing housings 4841 and 4842. In some embodiments, contact bearings may be included instead of or in addition to gas bearings. For example, one or both of bearing housings 4841 and 4842 may instead include a bearing surface configured to contact rail 4816 or otherwise limit azimuthal rotation of rail 4816 while allowing rail 4816 to slide axially. In some embodiments, two or more rails, three or more gas bearing housings, or both may be provided and configured to constrain azimuthal rotation of the translator. For example, a second rail and corresponding bearing housing may be positioned 180° from the first rail and corresponding bearing housing.In some embodiments, the rails and bearing housing may not be required, for example, another mechanism or component within the linear generator system (e.g., a stator) may constrain the azimuthal rotation of the translator.

[0161] The position sensor 4840 is configured to sense the relative or absolute position of the rail 4816 (and thus, for example, the relative position of other features of the translator 4800). In some embodiments, the translator 4800 is a rigid assembly (e.g., each component moves at substantially the same speed except for vibrations, pressure-induced strains, or other small perturbations). In some embodiments, for example, the position sensor 4840 can be an encoder readhead (e.g., a magnetic or optical encoder readhead) and the rail 4816 includes a corresponding encoder tape (e.g., a magnetic or optical tape). In some embodiments, the position sensor 4840 can include an encoder readhead (e.g., a magnetic or optical encoder readhead) and the rail 4816 includes one or more indexing features for indicating position. In some embodiments, the position sensor 4840 is stationary with respect to the translator 4800 and therefore can sense the relative movement of the translator with respect to a stator, a cylinder, a bearing housing, any other suitable component, or any combination thereof. For example, the position sensor 4840 can be rigidly mounted (e.g., fixed), flexibly mounted (e.g., mounted via a flexure), or integrated (e.g., as a single piece) to the stator, bearing housing, structural frame system, any other suitable mounting component, or any combination thereof. The position sensor 4840 can include an absolute sensor, a relative sensor, an incremental sensor, any other suitable sensor type for measuring the position of the translator 4800, or any combination thereof. In some embodiments, multiple rails, multiple position sensors, or both may be included. For example, a second rail and corresponding position sensor may be positioned 180° from the first rail and corresponding position sensor. In some embodiments, rails and position sensors may not be required. For example, another mechanism or component (e.g., the stator) within the linear generator system can determine the relative or absolute position of the translator.In some embodiments, the bearing housings 4841 and 4842 may include a mechanism to allow condensed liquid (eg, condensed water from the air) to drain from the bearing housings.

[0162] FIG. 49 shows a cross-sectional view of an example translator 4900 and stator 4970, along with an enlarged region 4980, according to some embodiments of the present disclosure. The cross-sectional view in FIG. 49 is in an axial position and shows a translator tube 4902, a magnet assembly 4903, and a stator 4970. The magnet assembly 4903 is coupled to the translator tube 4902 (e.g., using press-fit, bonding, adhesion (e.g., glue), wrapping, or other techniques to form a rigid assembly). The stator 4970 may include, for example, phase windings and stator teeth (e.g., iron or steel, laminated sheets). The stator 4970 forms an air gap 4972 with the magnet assembly 4903 of the translator 4900. The reluctance of the stator 4970 and translator 4900 assembly is proportional to the size of the air gap 4972. The air gap 4972 directly affects the electromagnetic interaction of the stator 4970 to translator 4900 assembly. In some embodiments, the stator 4970 can include an azimuthal gap 4971 that continues the axial length of the stator 4970 or a portion thereof, and the magnet assembly 4903 of the translator 4900 can include a corresponding azimuthal gap 4901 that continues the axial length of the magnet assembly 4903 or a portion thereof. The gaps in the stator (e.g., gap 4971) and the gaps in the magnet assembly (e.g., gap 4901) can be azimuthal aligned and can act to maintain the azimuthal position of the magnetic assembly 4903 relative to the stator 4970 (and thus, for example, the relative positions of the translator 4900 and stator 4970) during operation. The stator 4970 and translator 4900 can include any suitable number of corresponding gaps (e.g., the translator can include one or more gaps and the stator can include one or more gaps) configured to provide anti-clocking of the translator. When corresponding gaps in the stator and translator are azimuthal misaligned, an electromagnetic force is generated to align the gaps. For example, the dashed magnet assembly in the enlarged view of region 4980 indicates an azimuthal misalignment that will generate a restoring force FR.In some embodiments, one or more gaps in the stator may allow a phase winding to pass through for routing (e.g., by providing an open path for wires routed away from the phase winding). While shown as approximately equal in FIG. 49 , gap 4971 and gap 4901 need not be equal in azimuthal length. For example, in some embodiments, gap 4971 and gap 4901 may have different azimuthal lengths, and their corresponding centerline azimuthal positions may be aligned. In some embodiments, gap 4901, gap 4971, or both may encompass or include a dielectric material. For example, gap 4901 may be completely or partially filled with a plastic “dummy” magnet. In a further example, gap 4971 may include a plastic component to guide the phase winding that is passed through for routing.

[0163] FIG. 50 shows a cross-sectional view of a translator 5000 and a stator 5050 according to some embodiments of the present disclosure. In some embodiments, the stator 5050 may include one or more reliefs 5004 to accommodate each rail 5016, and optionally additional rails, during axial movement of the translator 5000 (e.g., when the rail 5016 is axially aligned with the stator 5050). In some embodiments, an air gap between the translator 5000 and the stator 5050 need not be maintained within the one or more reliefs 5004. In some embodiments, the stator includes one or more reliefs to accommodate corresponding features of the translator during axial movement of the translator. For example, a portion of the stator is configured to form an air gap with the translator (e.g., with a predetermined reluctance and dimensional tolerance), while other portions of the stator do not require an air gap with the translator. In some embodiments, the reliefs 5004 are not required. For example, the combination of rail height and air gap may be sufficient such that no reliefs are required. In a further embodiment, the rails may be attached to the translator in a position that prevents the rails from moving within the stator.

[0164] FIG. 51 shows a cross-sectional view of a translator 5100 and a bearing housing 5150, according to some embodiments of the present disclosure. In some embodiments, the bearing housing 5150 can include one or more reliefs 5104 for accommodating the rails 5116 and any other rails during axial movement of the translator 5100 (e.g., when the rails 5116 are axially aligned or otherwise overlapping with the bearing housing 5150). As shown in FIG. 51 , the gas bearings radially disposed between the bearing housing 5150 and the translator 5100 do not extend into the one or more reliefs 5104. In some embodiments, the gas bearings radially disposed between the bearing housing 5150 and the translator 5100 do extend into the one or more reliefs 5104. In some embodiments, as shown, the bearing housing 5150 is a clamshell-type structure, with two components mating together to form the complete bearing housing 5150, as shown in FIG. 51 . It should be noted that for clarity and ease of explanation, the drawings in this patent application are not necessarily drawn to scale and do not reflect the actual or relative size of each feature. The bearing housing may be of any suitable shape, such as, for example, circular, rectangular, polygonal, curved, or any other shape including a single segment or multiple segments. While shown as cylindrical in this disclosure, the translator “tube” may include any suitable cross-sectional shape or cross-sectional shape profile along its axial length. For example, the translator tube may include an outer surface that is a bearing surface, and the bearing surface may be flat, circular, curved, segmented, or any other suitable profile in which a bearing gap is formed to contain the gas bearing. In some embodiments, the gas bearing need not include a relief 5104. For example, the rail may be attached to the translator in a position that prevents the rail from moving within the gas bearing.

[0165] The cooling system is configured to facilitate the distribution of a cooling fluid (e.g., for air cooling) to various portions of the linear generator and housing. While the following description primarily refers to an air-cooled system, it will be understood that the cooling system can distribute and regulate any suitable cooling fluid (e.g., gas, liquid, or combinations thereof) in accordance with the present disclosure. Cooling can be performed to counteract energy transfer in the form of heat due to chemical processes (e.g., reaction of fuel and air), compression and expansion processes (e.g., compressive action of a working fluid), mechanical processes (e.g., from friction or viscous effects), electrical processes (e.g., ohmic losses in power electronics or electrical components), or combinations thereof.

[0166] 52 shows a system diagram of an exemplary cooling system 5200, according to some embodiments of the present disclosure. The exemplary cooling system 5200 includes a filter 5202, a duct 5203, a heat exchanger 5204, a fan 5206, cooling jackets 5250-5254, a duct 5260, any other suitable ducts (e.g., plenums, manifolds, tubing, piping, and fittings), louvers, sensors, any other suitable components (not shown), or any suitable combination thereof.

[0167] Fan 5206 is configured to draw ambient air or another suitable gas source through filter 5202, duct 5203, and heat exchanger 5204, which may be arranged in any suitable order upstream or downstream of fan 5206 and provide air to any suitable arrangement of cooling jackets 5250, 5251, 5252, 5253, and 5254. As exemplarily shown in FIG. 52, cooling air is supplied to cooling jacket 5250 (e.g., a cylinder housing a reaction section), from which the air enters duct 5260, which distributes the gas in parallel to cooling jackets 5251 and 5252 (e.g., disposed on respective stators) and cooling jackets 5253 and 5254 (e.g., disposed on respective gas springs). As the cooling gas flows through each cooling jacket 5250-5254, the temperature of the cooling gas may increase accordingly based on the heat load, the mass flow rate of the cooling gas, and the thermophysical properties of the cooling gas.

[0168] In some embodiments, the cooling jackets 5250-5254 include plenums that encapsulate, surround, or otherwise encase the components of the generator assembly 5290. In some embodiments, the cooling jackets 5250-5254 include internal passages, tubes, hoses, cooling plates, fins, or other cooling mechanisms configured to cool the components of the generator assembly 5290. For example, in some embodiments, the cooling jacket 5250 includes a cylindrical shroud azimuthally disposed around and outside the cylinder to direct airflow outside the cylinder. In further examples, in some embodiments, the cooling jackets 5253 and 5254 each include a respective cylindrical shroud azimuthally disposed around and outside the respective gas spring cylinder to direct airflow outside the respective gas spring cylinder. In some embodiments, the cooling jackets 5251 and 5252 are integrated into the respective stators of the generator assembly 5290. For example, the cooling jackets 5251 and 5252 can include passages internal to the respective stators (e.g., passages in the iron teeth of the stators). The cooling jackets may include manifolds, shrouds, vanes, any other suitable flow directing mechanism, or any combination thereof. Air provided from the fan 5206 may be directed along any suitable path within the cooling jackets 5250-5254. For example, in some embodiments, the cooling jackets 5250-5254 may all receive air in parallel from the duct 5260. In a further example, in some embodiments, some of the cooling jackets 5250-5254 may receive air in parallel with one another and in series with one or more other cooling jackets of the cooling jackets 5250-5254. In some embodiments, the cooling jackets 5250-5254 are arranged in series in any suitable order. For example, the order and arrangement may depend on the heat load, temperature limitations, piping routing, or a combination thereof. The linear generator system may include components not shown in FIG. 52 that have dedicated cooling paths (e.g., separate from the cooling jackets 5250-5254).For example, the power electronics, the control system enclosure, or both can be cooled separately (e.g., using a cooling jacket). In some embodiments, the airflow from cooling system 5200 can be used to maintain the power electronics and control enclosure at a positive pressure relative to the ambient to protect the electronic components from dust and other particles that may be harmful to their operation. In some embodiments, the airflow used to cool the electronic components can be treated in various ways, including heating and filtering to reduce moisture and particles from the cooling air. In a further example, sections of the translator can be cooled separately. In some embodiments, some of the cooling air downstream of cooling jacket 5250 can be directed away from duct 5260 for other cooling purposes (e.g., general cooling, stator cooling, bearing cooling, translator cooling).

[0169] In some embodiments, intake gas (e.g., filtered) from duct 5203 may be provided to boost blower 5210, which increases the pressure of the intake gas (e.g., air). In some embodiments, an additional filter may be provided to further filter the air before entering boost blower 5210 (e.g., a finer grade filter with a higher associated pressure drop). In some embodiments, the intake gas is diverted to boost blower 5210 upstream of filter 5202, with or without an additional filter. The intake gas may then be directed through heat exchanger 5204 (e.g., to cool the gas after boost blower 5210) and then to other appropriate components of the intake system before entering the intake breathing port of generator assembly 5290. In some embodiments, heat exchanger 5204 may be a gas-to-gas heat exchanger, a gas-to-liquid heat exchanger, or a combination thereof.

[0170] In some embodiments, some or all of the cooling jackets 5250-5254 may be omitted, combined, or otherwise modified from those shown in Figure 52 in accordance with the present disclosure. In some embodiments, additional cooling jackets not shown in Figure 52 may be included. For example, cooling jackets may be included to provide cooling to one or more bearing housings, seals, manifolds, or other system components (e.g., power electronics of a control system, or processing units of a control system).

[0171] In some embodiments, the cooling system can be configured to cool or heat portions of the cylinder, bearing housing, translator, or other suitable component to help bearing clearances and friction remain low enough to minimize damage, wear, or both. For example, the bearing gap can be selected to be as thin as possible without incurring frictional losses from contact due to thermal effects, off-axis loads, or other perturbations.

[0172] In some embodiments, the cooling system 5200 includes a cooling subsystem for cooling the translator. For example, a compressed gas system may be included to provide compressed gas to a translator surface (e.g., its bearing surface) to provide convection cooling of the translator. In some embodiments, the cooling system 5200 is configured to provide slightly heated gas (e.g., heated to a temperature above ambient temperature) to one or more components. For example, the cooling system 5200 may provide slightly heated air to electronics (e.g., within an enclosure or rack) to provide humidity protection (e.g., to avoid condensation). In some embodiments, the cooling system 5200 includes one or more controllable actuators that control flow paths to enable preferential heating or cooling of components.

[0173] The frame system is configured to maintain position, alignment, or both, and provide stiffness against deflection of the components of the integrated linear generator system. For example, the mounting components of the generator assembly can be secured to the frame system to prevent relative motion during operation. In some embodiments, for example, the linear generator can operate using gas bearings and relatively tight spatial tolerances. Therefore, maintaining spatial arrangement and alignment, taking into account structural influences (e.g., component weight and mounts), cyclic pressure loads, off-axis loads, thermal expansion, and other operational influences, is important for low-friction, long-term operation. For example, the frame system can provide alignment along any suitable direction (e.g., axial, azimuthal, radial, or any combination thereof).

[0174] FIG. 53 shows a top view of an exemplary frame system 5300, according to some embodiments of the present disclosure. The exemplary frame system 5300 includes end members 5301 and 5302, an axial member 5303, any other suitable components (not shown), or any suitable combination thereof. In some embodiments, the frame system 5300 is symmetrical or partially symmetrical about an axis 5350 (e.g., an axis around which the generator assembly is centered). In some embodiments, the axial member 5303 provides axial stiffness to the frame system 5300, axial alignment of components along the axis 5350 (e.g., components of the generator assembly can be mounted on the axial member 5303), or both. In some embodiments, the end members 5301 and 5302 are configured to counteract forces from their respective gas spring cylinders. For example, the gas springs can exert a large force axially outward on their respective gas spring heads (e.g., when the translator is outward and the gas spring is compressed). Thus, the end members 5301 and 5302 and the axial member 5303 can be configured to react against corresponding axial forces. The axial member 5303 can be welded, brazed, fastened (e.g., bolted), or otherwise attached to the end members 5301 and 5302. In some embodiments, the attachment of the axial member 5303 to the end members 5301 and 5302 can be rigid (e.g., through the use of tie rods or weldments). In some embodiments, the open area between the axial member 5303 and the end members 5301 and 5302 allows for relatively easy manufacture of the linear generator system by allowing components to be attached to the frame system 5300 from above (e.g., using a crane or other lifting device).

[0175] FIG. 54 shows a side view of an exemplary frame system 5400, according to some embodiments of the present disclosure. The exemplary frame system 5400 includes end members 5401 and 5402, an axial member 5403, a lateral member 5404, any other suitable components (not shown), or any suitable combination thereof. In some embodiments, the frame system 5400 provides longitudinal stiffness, lateral stiffness, azimuthal stiffness, or a combination thereof, to the components of the generator assembly. In some embodiments, for example, the frame system 5400 is symmetrical or partially symmetrical about an axis 5450 (e.g., the axis around which the generator assembly may be centered or otherwise aligned). In some embodiments, the axial member 5403 provides axial stiffness to the frame system 5400, axial alignment of the components along the axis 5450 (e.g., the components of the generator assembly may be mounted on the axial member 5403), or both. In some embodiments, the lateral member 5404 provides a mounting location, lateral stiffness, axial stiffness, or any combination thereof, to the components of the linear generator. In some embodiments, the end members 5401 and 5402 are configured to counteract forces from their respective gas spring cylinders. For example, the gas springs can exert a large force axially outward on their respective gas spring heads (e.g., when the translator is near the BDC position and the gas springs are compressed). Thus, the end members 5401 and 5402 can be configured to counteract corresponding axial forces. The axial member 5403 can be welded, brazed, fastened (e.g., bolted), or otherwise attached to the end members 5401 and 5402. The lateral member 5404 can be welded, brazed, fastened (e.g., bolted), or otherwise attached to the axial member 5403. The frame system can include any suitable number of lateral members positioned at any suitable angle relative to the axial member 5403.The axial spacing of the lateral members may be sufficient to facilitate maintenance (e.g., access to bearings, pistons, rings, stators, and other major components).

[0176] In some embodiments, the frame system includes one or more access areas arranged to accommodate components of the linear generator system. The frame system 5400 includes an access area 5491 of one or more members for receiving a first linear electromagnetic machine (LEM), an access area 5493 of one or more members for receiving a second LEM, an access area 5492 of one or more members for receiving a cylinder, an access area 5490 of one or more members for receiving a gas spring cylinder, and an access area 5494 of one or more members for receiving a gas spring cylinder. The frame system 5400 includes one or more openings between the one or more members, the one or more openings corresponding to the access areas 5490-5494. The access areas 5490 and 5494 can be aligned axially (e.g., along axis 5450), aligned laterally (e.g., relative to axis 5450), or both.

[0177] 55 shows a side view of an example assembly including a frame system 5500 coupled to a generator assembly 5550 (shown in cross section for illustrative purposes), according to some embodiments of the present disclosure. The example frame system 5500 includes end members 5501 and 5502, an axial member 5503, a lateral member 5504, any other suitable components (not shown), or any suitable combination thereof. The generator assembly 5550 can be secured to the frame system 5500. For example, components of the generator assembly 5550 (e.g., one or more cylinders, one or more stators, one or more bearing housings, one or more seals) can be aligned with, attached to, or both of one or more lateral members 5504, the axial member 5503, the end member 5501, the end member 5502, or a combination thereof. In some embodiments, components of the generator assembly 5550 may be aligned and / or secured to one or more lateral members 5504, axial member 5503, end member 5501, end member 5502, or combinations thereof using mount components, flexure components, or a combination thereof. In some embodiments, the lateral members may include openings configured to accommodate the generator assemblies, or components thereof. In some embodiments, one or more lateral members, or all of the lateral members, may include any suitable plate, support, or truss design. For example, the lateral members may include simple beams (e.g., welded box beams), plates with openings, or any other suitable design. In some embodiments, each respective lateral member may include an opening extending around the periphery of the respective lateral member, the opening configured to accommodate the generator assembly, or portions thereof. For example, in some embodiments, the opening in each lateral member may extend to the top of the lateral member, such that the generator assembly, or portions thereof, may be inserted laterally from the top.In further embodiments, portions of the generator assembly may be inserted, installed, or removed through one or more openings in the frame system or members thereof.

[0178] The exemplary frame system 5500 includes mounts 5590 and 5591. In some embodiments, at least one mount can be attached to the frame. For example, the linear generator can operate in one or more frequency ranges, and the at least one mount can damp vibrations from the linear generator. As shown, mounts 5590 and 5591 are attached to the frame system 5500. In some embodiments, the generator assembly 5550 operates in one or more frequency ranges, and the mounts 5590 and 5591 can damp vibrations from the linear generator (e.g., in one or more frequency ranges). Mounts 5590 and 5591 can be separate, part of a mounting system, combined, omitted, or otherwise modified according to some embodiments of the present disclosure. In some embodiments, one or more mounts can include rollers or wheels for transporting the frame system 5500.

[0179] Generator assembly 5550 includes cylinder 5551 (gas spring), bearing housing 5552, translator 5553, stator 5554, bearing housing 5555, cylinder 5556, translator 5557, bearing housing 5558, stator 5559, bearing housing 5560, and cylinder 5561 (gas spring), as shown. Bearing housings 5552 and 5555, translator 5553, and stator 5554 form a first LEM, and bearing housings 5558 and 5560, translator 5557, and stator 5559 form a second LEM. In some embodiments, the first LEM and second LEM are aligned with one another using frame system 5500. In some embodiments, stator 5554 and stator 5559 are aligned with one another using frame system 5500, an assembly table and associated fixtures on which frame system 5500 rests, or both. For example, a first LEM may be laterally aligned relative to a second LEM (e.g., to align the stator bores of the first and second LEMs' respective stators). In further examples, a first LEM may be axially aligned relative to a second LEM (e.g., to set the longitudinal spacing between the first and second LEMs). In exemplary examples, when aligning components with one another using the frame system 5500, this involves positioning the components relative to one another and to the frame system 5500 to achieve the desired alignment. Once positioned, the associated components may be constrained or otherwise secured by attachment, mechanical engagement, boundaries defined by the frame system 5500, constraints imposed by one or more other components constrained or otherwise secured by the frame system 5500, other suitable mechanisms for constraining or securing components to the frame system 5500, or any combination thereof.

[0180] The generator assembly 5550 may be the same as or similar to, for example, the generator assembly 200 of FIG. 2. In some embodiments, the generator assembly 5550 may include one or more subassemblies that may, but need not, be coupled to one another. For example, in some embodiments, the stators 5554 and 5559 (e.g., with or without corresponding bearing housings connected thereto) may be mounted to the frame system 5500. The cylinders 5551, 5556, and 5561 may also be mounted to the frame system 5500 to align with the corresponding stators 5554 and 5559. Thus, the frame system 5500 may help align or maintain alignment of the components of the generator assembly 5550. In some embodiments, the frame system 5500 may include positioning features (e.g., pins), mounting features (e.g., hole patterns, threaded studs), alignment features (e.g., adjustable mounts), or combinations thereof, which may engage with corresponding features on the generator assembly.

[0181] In an exemplary embodiment, the linear generator can include a structural frame (e.g., frame system 5500), a cylinder (e.g., cylinder 202 in FIG. 2), a first LEM (e.g., LEM 256 in FIG. 2), and a second LEM (e.g., LEM 252 in FIG. 2). The cylinder can be attached to a central region of the structural frame. The first LEM is disposed on a first longitudinal side of the cylinder and is attached to the structural frame. The second LEM is disposed on a second longitudinal side of the cylinder and is attached to the structural frame. The second longitudinal side is opposite the first longitudinal side. The second LEM is aligned with the first LEM, and the cylinder is aligned with the first and second LEM. In other embodiments, the first LEM is aligned with the second LEM, and the cylinder is aligned with the first and second LEM. For example, any suitable components of linear generator 200 of FIG. 2 can be aligned with one another using a structural frame and corresponding mounting components. In a further example, the linear generator may further include a first gas spring cylinder (e.g., cylinder 204 of FIG. 2 ) attached to the structural frame and aligned with a first LEM (e.g., LEM 256 of FIG. 2 ), and a second gas spring cylinder (e.g., cylinder 205 of FIG. 2 ) attached to the structural frame and aligned with a second LEM (e.g., LEM 252 of FIG. 2 ). In a further example, the structural frame may include one or more openings in its top surface that allow for insertion of the cylinders, the first LEM, and the second LEM into the structural frame, as well as insertion of other components into the structural frame. In a further example, the cylinder (e.g., cylinder 202 of FIG. 2 ) may be attached to the structural frame (e.g., frame system 5500) by one or more flexures, mounts, or both (e.g., as shown in FIGS. 56-58 ). In some embodiments, the auxiliary device may be attached to the structural frame.For example, one or more power electronics systems may be mounted outside the frame system, near the stator, to reduce connector length, ohmic losses, and electromagnetic interference (EMI). In a further example, an air intake system (with or without a fuel system), an exhaust system, or both, may be mounted on top of the frame system. In a further example, each component required for testing, operation, or both of the generator assembly may be mounted on the frame system. The frame system 5500 includes mounting areas similar to the frame system 5400 of FIG. 54 for convenient access to the components of the generator assembly (e.g., for assembly, maintenance, or both). As shown, the frame system 5500 includes a tie rod 5509 configured to provide a compressive force to the frame system 5500 (e.g., with or without a compressive preload in a non-operating state). The frame system may include one tie rod, two or more tie rods, or none, according to some embodiments of the present disclosure. In some embodiments, the frame system (e.g., frame system 5500) is configured to limit the elongation of the frame members within a predetermined range (e.g., less than 250 microns, less than 500 microns, less than 1 mm, less than 5 mm, or other suitable range). For example, due to stresses resulting from thermal and pressure effects, the frame system may undergo strain in one or more directions. The strain may be quasi-steady (e.g., occurring on a relatively large time scale compared to the cycle) or periodic or near-periodic (e.g., resulting from the operation of the cycle). The frame system 5500 may be configured to provide compliance (e.g., axial compliance) to one or more components while maintaining the centerline of a cylinder, a stator, a bearing housing, any other suitable component, or any combination thereof.

[0182] FIG. 56 shows an end view of an exemplary frame system 5600, according to some embodiments of the present disclosure. For example, the frame system 5600 can be similar to the frame system 5300 of FIG. 53 and the frame system 5400 of FIG. 54. The end member 5601 includes an opening 5606 (e.g., to accommodate a gas spring cylinder) and a feature 5604. The exemplary feature 5604 includes a notch disposed near the attachment location of the axial member 5603 to reduce stiffness between the portion of the end member 5601 near the opening 5606 and the portion of the end member 5601 near the attachment location of the axial member 5603. For example, during operation of the integrated linear generator system, the gas spring cylinder can exert an outwardly directed axial force on the end member 5601 near the opening 5606. The feature 5604 can allow the axial force experienced by the axial member 5603 to be reduced accordingly. For example, the feature 5604 may allow the portion of the end member 5601 between the opening 5606 and the axial member 5603 to function as a flexure. In a further example, the feature 5604 reduces the force transmitted to the axial member 5603, and therefore the deflection experienced by the axial member 5603. When the corresponding translator is at or near the BDC, the end member 5601 may be subjected to large axial forces, which may cause the axial member 5603 to deflect. The feature 5604 reduces the force transmission to the axial member 5603, and therefore the deflection. The reduced deflection of the axial member 5603 may help maintain the alignment of components coupled to the frame system 5600. Although not shown in FIG. 56 , the end member 5601 may include a bolt pattern, a bolt circle, one or more protruding studs (e.g., threaded studs), one or more positioning features (e.g., pins, holes, slots), or any other suitable mounting feature. For example, in some embodiments, end members 5601 and 5602 include hole patterns for mounting corresponding gas spring cylinders (e.g., having corresponding flanges with corresponding retention patterns). In some embodiments, feature 5604 need not be included.

[0183] FIG. 57 shows a cross-sectional view of a portion of an exemplary integrated linear generator system including an end member 5702, a gas spring cylinder 5703, and a head 5705, according to some embodiments of the present disclosure. In some embodiments, the gas spring cylinder 5703 mates with an opening in the end member 5702. For example, the end member 5702 and the gas spring cylinder 5703 can include one or more corresponding locating features 5710. The locating features 5710 can include, for example, stud arrangements, pin arrangements, hole arrangements, slot arrangements, other suitable features for constraining the relative positions of the end member 5702 and the gas spring cylinder 5703, or any suitable combination thereof. For example, the locating features 5710 can include corresponding bolt circles on each of the end member 5702 and the gas spring cylinder 5703, as well as a set of locating pins on one component and corresponding holes on the other component. In some embodiments, the gas spring cylinder 5703 can include a flange 5706 configured to mate with the end member 5702. The flange 5706 can be positioned at any suitable axial location on or as part of the gas spring cylinder 5703. For example, the flange 5706 can be joined to the head 5705 and the end member 5702. In further examples, the flange 5706 can be positioned at a distal end of the cylinder 5703 relative to the head 5705. In further examples, the flange 5706 can be positioned so as not to impact the high pressure port, low pressure, cooling jacket, or a combination thereof. In some embodiments, the end member 5702 includes one or more mechanisms similar to mechanism 5604 of FIG. 56 for adjusting the axial stiffness of one or more portions of the end member 5702. The end member 5702 is configured to provide compliance (e.g., axially) via mechanism 5604 while maintaining a centerline of alignment of the cylinder 5703.

[0184] FIG. 58 shows a side view of an exemplary assembly 5800 including a cylinder 5802 with mounts 5820 and 5822, according to embodiments of the present disclosure. As shown, in some embodiments, a first cylinder mount 5820 and a second cylinder mount 5822 are attached to the cylinder 5802. The cylinder mounts 5820 and 5822 are attached to the cylinder and attached to the frame to substantially immobilize the cylinder 5802. The cylinder mounts 5820 and 5822 can be attached to any suitable component of the frame (e.g., axial members, lateral members, or both). In some embodiments, the cylinder mounts 5820 and 5822 can be configured to or include mechanisms that allow movement of the cylinder 5802 or change in dimensions of the cylinder 5802 (e.g., due to thermal expansion). For example, the first cylinder mount 5820 can be axially rigid and constrain its mounting position to the cylinder 5802. In further examples, the second cylinder mount 5822 is axially flexible, allowing the cylinder 5802 to expand and contract axially (e.g., due to thermal expansion). In some embodiments, both the first cylinder mount 5820 and the second cylinder mount 5822 are radially rigid, restraining the cylinder 5802 from significant radial movement. The first cylinder mount 5820 and the second cylinder mount 5822 can be positioned in any suitable axial location (e.g., on either side of the breathing manifolds 5810 and 5812). In exemplary examples, the first cylinder mount can be attached to the intake-side cylinder (e.g., inside the intake breathing manifold 5810 as shown), and the second cylinder mount can be attached to the exhaust-side cylinder (e.g., outside the exhaust breathing manifold 5812 as shown), where the intake end is the location of axial restraint. Intake breathing ports 5811 are axially disposed within intake manifold 5810, and exhaust breathing ports 5813 are axially disposed within exhaust manifold 5812. In some embodiments, cylinder mounts 5820 are integrated into or part of manifold 5810.In some embodiments, the cylinder mounts 5822 are integrated into or part of the manifold 5812. For example, the intake cylinder mounts 5820 can be attached to or feature on the intake manifold 5810 on either side of the manifold or on both sides of the manifold. In another example, the exhaust cylinder mounts 5822 can be attached to or feature on the exhaust manifold 5812 on either side of the manifold or on both sides of the manifold. The assembly 5800 is configured to provide tracking (e.g., axial) of the cylinder 5802 while maintaining a centerline of alignment of the cylinder 5802 (which may be aligned, e.g., with one or more stator bores, one or more bearing housings, one or more other cylinders, any other suitable component, or any combination thereof).

[0185] 59 shows an exemplary cylinder assembly 5900 with an intake manifold 5910 having a mount 5920, according to some embodiments of the present disclosure. The cylinder assembly 5900 includes a cylinder 5902 (e.g., having an intake port 5911 and an exhaust port 5913), an intake manifold 5910, an exhaust manifold 5912, a mount 5920, a mount 5930, and a flexure 5922. The mount 5920 is configured to attach the intake manifold 5910 to a structural frame (not shown). The mount 5930 is configured to attach the exhaust manifold 5912 to the structural frame (not shown) via the flexure 5922. For example, the flexure 5922 may allow axial displacement of the cylinder 5902 due to thermal expansion without incurring significant stress. In further examples, flexure 5922 can be relatively stiff with respect to lateral displacement of cylinder 5902 (e.g., so as to maintain alignment of axis 5970 with the stator bore). Assembly 5900 is configured to provide compliance of cylinder 5902 (e.g., axially) while maintaining a centerline of alignment of cylinder 5902 (e.g., which may be aligned with one or more stator bores, one or more bearing housings, one or more other cylinders, any other suitable component, or any combination thereof).

[0186] FIG. 60 shows a perspective view of an exemplary core 6000 according to some embodiments of the present disclosure. As shown, the core 6000 includes a generator assembly and frame 6050, an intake system 6010, a fuel system 6020, an exhaust system 6030, power electronics 6070 (e.g., for the intake-side LEM), and power electronics 6071 (e.g., for the exhaust-side LEM). The core 6000 may include any suitable components that enable testing, characterization, or both. For example, the core 6000 may be electrically coupled to a load bank (e.g., a set of resistive elements) for testing (e.g., to dissipate power generated during testing), an AC grid, a DC grid, or any other electrical load before installation in a full package assembly (e.g., as shown in FIG. 61). In some embodiments, one or more subsystems may include backup components that provide redundancy, resilience, and enable continued operation or controlled shutdown in the event of one or more component failures during operation.

[0187] FIG. 61 shows a perspective view of an exemplary integrated linear generator system 6100 according to some embodiments of the present disclosure. The integrated linear generator system 6100 includes an enclosure 6150, a core 6000, and a core 6001. FIG. 61 shows the core 6000 attached to the enclosure 6150, with the core 6001 partially attached / removed. The enclosure 6150 includes a rail system 6198 that can engage with the structural frame of either core to attach and remove each of the cores 6000 and 6001. By including separate cores (e.g., cores 6000 and 6001), the integrated linear generator system 6100 exhibits modularity, allowing for replacement or repair of the cores rather than the entire system. According to the present disclosure, the enclosure can be configured to house any suitable number of cores. In some embodiments, enclosure 6150 includes intake device 6010 (e.g., for supplying intake gas to cores 6000 and 6001), exhaust device 6120 (e.g., for receiving exhaust gas from cores 6000 and 6001), and electronics 6130 (e.g., may include a control system for controlling cores 6000 and 6001). For example, in some embodiments, intake device 6010 couples to intake system 6010 of core 6000. In further examples, in some embodiments, exhaust system 6120 couples to exhaust system 6030 of core 6000. In further examples, in some embodiments, electronics 6130 couples to power electronics 6070 and 6071 of core 6000.

[0188] In some embodiments, one or more components, systems, or auxiliary devices may be shared between cores. For example, an exhaust conditioned pipe may be shared between multiple cores (e.g., each core need not have a dedicated exhaust system or its dedicated conditioned pipe). In some embodiments, two or more packages (e.g., similar to the integrated linear generator system 6100 of FIG. 61) may be in communication with each other. For example, the packages may be communicatively linked to each other via a communications network (e.g., any suitable wired or wireless network). In further examples, the packages may be linked by a shared fuel system, a shared cooling system, a shared air intake system, a shared exhaust system, a shared control system, a shared power electronics system, any other suitable shared system, or any combination thereof. In some embodiments, one or more cores may be synchronized with other cores to achieve operating requirements, including efficiency, power, or noise.

[0189] It will be understood that the present disclosure is not limited to the embodiments described herein and may be implemented in the context of any suitable system. In some suitable embodiments, the present disclosure is applicable to reciprocating engines and compressors. In some embodiments, the present disclosure is applicable to engines and compressors. In some embodiments, the present disclosure is applicable to reciprocating engines and combustion and reaction devices such as engines. In some embodiments, the present disclosure is applicable to non-combustion and non-reaction devices such as reciprocating compressors and compressors. In some embodiments, the present disclosure is applicable to gas springs. In some embodiments, the present disclosure is applicable to oil-free reciprocating engines and engines and compressors. In some embodiments, the present disclosure is applicable to oil-free engines with internal or external combustion or reaction. In some embodiments, the present disclosure is applicable to oil-free engines operating with compression ignition (e.g., homogeneous charge compression ignition, stratified charge compression ignition, or other compression ignition), spark ignition, or both. In some embodiments, the present disclosure is applicable to oil-free engines operating with gas fuel, liquid fuel, or both. In some embodiments, the present disclosure is applicable to linear engines. In some embodiments, the present disclosure is applicable to engines that can be combustion engines with internal combustion / reaction, or any type of heat engine with external heat addition (e.g., from a heat source or external reaction such as combustion).

[0190] The foregoing is merely illustrative of the principles of the present disclosure, and various modifications can be made by those skilled in the art without departing from the scope of the present disclosure. The above-described embodiments are presented for purposes of illustration and not limitation. The present disclosure may also take many forms other than those expressly described herein. It is therefore emphasized that the present disclosure is not limited to the methods, systems, and apparatus expressly disclosed, but is intended to include all such variations and modifications within the spirit and scope of the following claims.

Claims

[Claim 1] The invention described in this specification.

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