Systems and methods for hydraulic control of excavators and other power machines

Abstract

A hydraulic system 403 for a power machine 100 is provided. The hydraulic system 403 can include a supply system 510 configured to provide pressurized fluid to a hydraulic actuator 630 and an energy recovery system 540. The energy recovery system 540 can include an energy storage device 650, a first valve that includes a first position that permits an outflow from the hydraulic actuator 630 to flow across the first valve and a second position that blocks the outlet flow from the hydraulic actuator 630 from flowing across the first valve, and a second valve that is arranged to control flow of the outlet flow from the hydraulic actuator 630 to the energy storage device 650.

Description

Attorney Docket No.: B2023-0036-W01SYSTEMS AND METHODS FOR HYDRAULIC CONTROL OF EXCAVATORS AND OTHER POWER MACHINES CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States provisional application no.63 / 749,931, filed 27 January 2025, which is hereby incorporated by reference in its entirety as though fully set forth hereinBACKGROUND

[0002] This disclosure is directed toward power machines. More particularly, this disclosure is directed to excavators and control systems for excavators and workgroups thereof.

[0003] Power machines, for the purposes of this disclosure, include any type of machine that generates power to accomplish a particular task or a variety of tasks. One type of power machine is a work vehicle. Work vehicles are generally self-propelled vehicles that have a work device, such as a lift arm (although some work vehicles can have other work devices) that can be manipulated to perform a work function. Work vehicles include excavators, loaders, utility vehicles, tractors, and trenchers, to name a few examples.

[0004] Excavators are a known type of power machine that generally have an undercarriage and a house that selectively rotates on the undercarriage. A lift arm, to which an implement can be attached, is operably coupled to the house and moveable under power with respect to the house. Excavators are also typically self-propelled vehicles. Typical excavators include one or more operator input devices (e g., joysticks or pedals) that are physically moved by an operator to directly adjust hydraulic fluid flow through a particular component of the excavator (e.g., a control valve for an actuator for a lift arm) thereby adjusting the movement of a particular component (e.g.. the lift arm).

[0005] The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.SUMMARY

[0006] According to some aspects of the disclosure, a hydraulic system for a power machine is provided. The hydraulic system can include a supply system that is configured to provide pressurized fluid to a hydraulic actuator and an energy recovery system. The energyAttorney Docket No.: B2023-0036-W01recovery system can include an energy storage device, a first valve, and a second valve. The first valve can move between a first position that permits an outflow from the hydraulic actuator to flow across the first valve and a second position that blocks the outlet flow from the hydraulic actuator from flowing across the first valve. The second valve can be arranged to control flow of the outlet flow from the hydraulic actuator to the energy storage device.

[0007] According to some aspects of the disclosure, a method of recovenng energy from one or more hydraulic actuators of a power machine is provided. Whether an actuator is a highest-load actuator can be determined. Upon determining that the actuator is the highest-load actuator, a working mode (e.g., a resistive load mode or an overrunning load mode) of the actuator of the one or more hydraulic actuators can be determined. Upon determining that the working mode is a resistive load mode, one or more valves of an energy recovery system can be controlled to divert an outflow from the actuator to tank. Upon determining that the working mode is an overrunning load mode, a maximum pressure of the outflow from the actuator can be determined. Based on the determined maximum pressure, the one or more valves of the energy recovery system can be selectively controlled to route the outflow from the actuator to an energy storage device of the energy recovery system or to divert the outflow from the actuator to tank. Pressurized flow from the energy storage device can be released to boost a supply system that provides pressurized fluid to the one or more hydraulic actuators.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The following drawings are provided to help illustrate various features of nonlimiting examples of the disclosure and are not intended to limit the scope of the disclosure or exclude alternative implementations.

[0009] FIG. 1 is a block diagram illustrating functional systems of a representative power machine on which embodiments of the present disclosure can be practiced.

[0010] FIG. 2 is a front left axonometric view of a representative power machine in the form of an excavator on which the disclosed embodiments can be practiced.

[0011] FIG. 3 is a rear right axonometric view of the excavator of FIG. 2.

[0012] FIG. 4 is a schematic illustration of a control system for a power machine.Attorney Docket No.: B2023-0036-W01

[0013] FIG. 5 is a block diagram illustrating an example hydraulic system for a power machine.

[0014] FIG. 6A is a diagrammatic illustration of an example energy recovery system of the hydraulic system of FIG. 5.

[0015] FIG. 6B is a diagrammatic illustration of an alternate configuration of the energy recovery system of FIG. 6A.

[0016] FIG. 7A is a diagrammatic illustration of an example energy recovery system of the hydraulic system of FIG. 5.

[0017] FIG. 7B a diagrammatic illustration of an alternate configuration of the energy recovery system of FIG. 7A.

[0018] FIG. 8A a diagrammatic illustration of an example energy recovery system of the hydraulic system of FIG. 5.

[0019] FIG. 8B a diagrammatic illustration of an alternate configuration of the energy recovery system of FIG. 8 A.

[0020] FIG. 9 is a flowchart illustrating a method of operating an energy recovery system, according to examples of the disclosed technology.

[0021] FIG. 10 is a flowchart illustrating a control method for the energy recovery system of FIGS. 6A and 6B.

[0022] FIG. 11 is a flowchart illustrating a control method for the energy7recovery system of FIGS. 7 A and 7B.

[0023] FIG. 12 is a flowchart illustrating a control method for the energy recovery system of FIGS. 8 A and 8B.

[0024] FIG. 13 is a flowchart illustrating a method of controlling an energy recovery system, according to examples of the disclosed technology.

[0025] FIG. 14 is a flowchart illustrating a control method for discharging an energy recovery device to a supply system of the hydraulic system of FIG. 5.Attorney Docket No.: B2023-0036-W01

[0026] FIG. 15 is a simplified hydraulic diagram illustrating an example configuration of workgroup systems of a power machine with an energy recovery system, according to examples of the disclosed technology.

[0027] FIG. 16 is a diagram illustrating power savings and losses during operation of the workgroup system of FIG. 15.

[0028] FIG. 17 is a simplified hydraulic diagram illustrating an example configuration of workgroup systems of a power machine with an energy7recovery system, according to examples of the disclosed technology.

[0029] FIG. 18 is a simplified hydraulic diagram illustrating an example configuration of workgroup systems of a power machine with an energy7recovery system, according to examples of the disclosed technology.

[0030] FIG. 19 is a simplified hydraulic diagram illustrating an example configuration of workgroup systems of a power machine with an energy7recovery7system, according to examples of the disclosed technology.

[0031] FIGS. 20 is a diagram illustrating energy^ recovery^ for some operations with the operational systems of FIGS. 17-19.

[0032] FIG. 21A is a hydraulic diagram illustrating an example supply system of the hydraulic system of FIG. 5.

[0033] FIG. 21B is a hydraulic diagram illustrating an alternate configuration of the supply system of FIG. 21 A.

[0034] FIG. 22A is a hydraulic diagram illustrating another example supply system of the hydraulic system of FIG. 5.

[0035] FIG. 22B is a hydraulic diagram illustrating an alternate configuration of the supply system of FIG. 22A.

[0036] FIG. 22C is a hydraulic diagram illustrating an alternate configuration of the supply system of FIG. 22A.Attorney Docket No.: B2023-0036-W01

[0037] FIG. 23 is a diagram illustrating operational envelopes of pumps of any one of the hydraulic systems of FIGS. 22A-22C.

[0038] FIG. 24 is a simplified hydraulic diagram illustrating an example energy recovery system and an example supply system of the hydraulic system of FIG. 5, according to examples of the disclosed technology.DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE

[0039] The concepts disclosed in this discussion are described and illustrated by referring to exemplary embodiments. These concepts, however, are not limited in their application to the details of construction and the arrangement of components in the illustrative embodiments and are capable of being practiced or being carried out in various other ways.

[0040] Typical excavators (and other power machines) can include one or more workgroup elements that are operatively coupled (e.g., mechanically or hydraulically coupled) to a hydraulic system of the excavator. For example, one or more extendable hydraulic actuators can be provided for lift arm assemblies or other workgroup actuators (e.g., a boom cylinder, an arm cylinder, a bucket cylinder, an auxiliary cylinder, etc.), in hydraulic communication with a supply pump (e.g., dedicated workgroup hydraulic pump).

[0041] In some cases, an actuator can operate in a particular mode based on present operating conditions (e.g., corresponding to a directional movement of the actuator piston, and directional load on the actuator). As one example, a particular operation (under load) can generally be classified as being either in resistive mode or overrunning mode. For an extendable actuator, overrunning mode corresponds to an external load acting in the same direction as (i.e., with) the motion of an actuator, whereas resistive mode corresponds to an external load acting in an opposite direction to (i.e., against) the motion of the actuator. For example, an arm actuator can retract in a resistive mode to raise an excavator arm against gravity relative to a boom, or a boom actuator can retract in an overrunning mode to lower an excavator bucket with gravity toward the ground.

[0042] In conventional power machines, during overrunning mode in particular, some pow er provided to the w orkgroup actuator may essentially be w asted, i.e., not used or necessary7to complete the commanded operation, and not available to be used in or for other hydraulic operations. For example, in some conventional designs, high pressure fluid outflow from anAttorney Docket No.: B2023-0036-W01actuator may simply be passed through an orifice to tank, and the pressure energy of the fluid may thus be lost through throttling and other turbulent dissipation (e.g.. in the return flow into the tank). Thus, it may be beneficial to provide a hydraulic system that can recover energy that is lost during operations of workgroup cylinders, or that can more effectively regulate the backpressure of workgroup systems in various operational modes, including to recover excess energy for particular operations and to improve overall operational efficiency and efficacy.

[0043] Examples of the present disclosure can address these problems, for example, by providing an energy recovery system to recover excess energy' from pressurized hydraulic fluid that is discharged from one or more workgroup actuators of a power machine. In particular, some energy recovery systems according to the disclosure can include one or more valves that can be controlled to direct hydraulic outflow from one or more operational actuators (e.g., workgroup actuators) selectively to tank or to an energy' storage device (e.g., an accumulator). In different examples, the one or more valves can be selectively controlled to direct the hydraulic flow based on a pressure condition of an outflow from one or more operational actuators, or based on various other system conditions, as further detailed below.

[0044] In some examples, recovered hydraulic energy' can be stored in the energy storage device and then released to provide supplemental or replacement flow to a supply pump based on demands of the hydraulic system. In other examples, recovered energy may be converted to other forms to otherwise boost available power or flow of a relevant supply^ system. In some cases, systems as disclosed herein can also (or alternatively) help to reduce throttling losses by more effectively regulating backpressure for workgroup operations. Accordingly, and as further detailed below, the disclosed technology can generally provide improved efficiency and operational capabilities for various power machine systems.

[0045] The concepts presented herein can be practiced on various power machines, as will be described below. A representative power machine on which the embodiments can be practiced is illustrated in diagram form in FIG. 1 and one example of such a power machine is illustrated in FIGS. 2-3 and described below before any embodiments are disclosed. For the sake of brevity', only one power machine is discussed. However, as mentioned above, the embodiments below can be practiced on any of a number of power machines, including power machines of different types from the representative power machine shown in FIGS. 2-3. Power machines, for the purposes of this discussion, include a frame, at least one work element, and a power source that can provide power to the work element to accomplish a work task. OneAttorney Docket No.: B2023-0036-W01type of power machine is a self-propelled work vehicle. Self-propelled work vehicles are a class of power machines that include a frame, work element, and a power source that can provide power to the work element. At least one of the work elements is a motive system for moving the power machine under power.

[0046] Referring now to FIG. 1. a block diagram illustrates the basic systems of a power machine 100 upon which the embodiments discussed below can be advantageously incorporated and can be any of several distinct ty pes of power machines. The block diagram of FIG. 1 identifies various systems on power machine 100 and the relationship between various components and systems. As mentioned above, at the most basic level, power machines for the purposes of this discussion include a frame, a power source, and a work element. The power machine 100 has a frame 110, a power source 120, and a work element 130. Because power machine 100 shown in FIG. 1 is a self-propelled work vehicle, it also has tractive elements 140, which are themselves work elements provided to move the power machine over a support surface and an operator station 150 that provides an operating position for controlling the work elements of the power machine. A control system 160 is provided to interact with the other systems to perform various work tasks at least in part in response to control signals provided by an operator.

[0047] Certain work vehicles have work elements that can perform a dedicated task. For example, some work vehicles have a lift arm to which an implement such as a bucket is attached such as by a pinning arrangement. The work element, e.g., the lift arm, can be manipulated to position the implement for performing the task. The implement, in some instances can be positioned relative to the work element, such as by rotating a bucket relative to a lift arm, to further position the implement. Under normal operation of such a work vehicle, the bucket is intended to be attached and under use. Such work vehicles may be able to accept other implements by disassembling the implement / work element combination and reassembling another implement in place of the original bucket. Other work vehicles, however, are intended to be used with a wide variety of implements and have an implement interface such as implement interface 170 shown in FIG. 1. At its most basic, implement interface 170 is a connection mechanism between the frame 110 or a work element 130 and an implement, which can be as simple as a connection point for attaching an implement directly to the frame 110 or a work element 130 or more complex, as discussed below.Attorney Docket No.: B2023-0036-W01

[0048] On some power machines, implement interface 170 can include an implement carrier, which is a physical structure movably attached to a work element. The implement carrier has engagement features and locking features to accept and secure any of several implements to the work element. One characteristic of such an implement carrier is that once an implement is attached to it, it is fixed to the implement (i.e., not movable with respect to the implement) and when the implement carrier is moved with respect to the work element, the implement moves with the implement carrier. The term implement carrier is not merely a pivotal connection point, but rather a dedicated device specifically intended to accept and be secured to various different implements. The implement carrier itself is mountable to a work element 130 such as a lift arm or the frame 110. Implement interface 170 can also include one or more power sources for providing power to one or more work elements on an implement. Some power machines can have a plurality of work elements with implement interfaces, each of which may, but need not, have an implement carrier for receiving implements. Some other power machines can have a work element with a plurality of implement interfaces so that a single work element can accept a plurality of implements simultaneously. Each of these implement interfaces can, but need not, have an implement carrier.

[0049] Frame 110 includes a physical structure that can support various other components that are attached thereto or positioned thereon. The frame 110 can include any number of individual components. Some power machines have frames that are rigid. That is, no part of the frame is movable with respect to another part of the frame. Other power machines have at least one portion that can move with respect to another portion of the frame. For example, excavators can have an upper frame portion that rotates about a swivel with respect to a lower frame portion. Other work vehicles have articulated frames such that one portion of the frame pivots with respect to another portion for accomplishing steering functions. In exemplary embodiments, at least a portion of the power source is located in the upper frame or machine portion that rotates relative to the lower frame portion or undercarriage. The power source provides power to components of the undercarriage portion through the swivel.

[0050] Frame 110 supports the power source 120, which can provide power to one or more work elements 130 including the one or more tractive elements 140, as well as, in some instances, providing power for use by an attached implement via implement interface 170. Power from the power source 120 can be provided directly to any of the work elements 130, tractive elements 140, and implement interfaces 170. Alternatively, power from the powerAttorney Docket No.: B2023-0036-W01source 120 can be provided to a control system 160, which in turn selectively provides power to the elements that are capable of using it to perform a work function. Power sources for power machines typically include an engine such as an internal combustion engine and a power conversion system such as a mechanical transmission or a hydraulic system that can convert the output from an engine into a form of power that is usable by a work element. Other types of power sources can be incorporated into power machines, including electrical sources or a combination of power sources, known generally as hybrid power sources.

[0051] FIG. 1 shows a single work element designated as work element 130, but various power machines can have any number of work elements. Work elements are typically attached to the frame of the power machine and movable with respect to the frame when performing a work task. In addition, tractive elements 140 are a special case of work element in that their work function is generally to move the power machine 100 over a support surface. Tractive elements 140 are shown separate from the work element 130 because many power machines have additional work elements besides tractive elements, although that is not always the case. Power machines can have any number of tractive elements, some or all of which can receive power from the power source 120 to propel the power machine 100. Tractive elements can be, for example, wheels attached to an axle, track assemblies, and the like. Tractive elements can be rigidly mounted to the frame such that movement of the tractive element is limited to rotation about an axle or steerably mounted to the frame to accomplish steering by pivoting the tractive element with respect to the frame. In contrast to tractive elements and actuators, workgroup actuators and elements are configured to provide powered movement of one or more components of a power machine for work operations (i.e., other than for travel of the power machine over terrain). Correspondingly, “workgroup function” refers to one or more functions that relate to movement of one or more components of a power machine other than for travel of the power machine over terrain.

[0052] Power machine 100 includes an operator station 150, which provides a position from which an operator can control operation of the power machine. In some power machines, the operator station 150 is defined by an enclosed or partially enclosed cab. Some power machines on which the disclosed embodiments may be practiced may not have a cab or an operator compartment of the type described above. For example, a walk behind loader may not have a cab or an operator compartment, but rather an operating position that serves as an operator station from which the power machine is properly operated. More broadly, powerAttorney Docket No.: B2023-0036-W01machines other than work vehicles may have operator stations that are not necessarily similar to the operating positions and operator compartments referenced above. Further, some power machines such as power machine 100 and others, whether they have operator compartments or operator positions, may be capable of being operated remotely (i.e., from a remotely located operator station) instead of or in addition to an operator station adjacent or on the power machine. This can include applications w here at least some of the operator-controlled functions of the power machine can be operated from an operating position associated with an implement that is coupled to the power machine. Alternatively, with some power machines, a remotecontrol device can be provided (i.e., remote from both of the power machine and any implement to which is it coupled) that can control at least some of the operator-controlled functions on the power machine.

[0053] FIGS. 2-3 illustrate an excavator 200, which is one particular example of a power machine of the type illustrated in FIG. 1, on which the disclosed embodiments can be employed. Unless specifically noted otherwise, embodiments disclosed below can be practiced on a variety of power machines, with the excavator 200 being only one of those power machines. Excavator 200 is described below for illustrative purposes. Not every excavator or power machine on which the illustrative embodiments can be practiced need have all the features or be limited to the features that excavator 200 has. Excavator 200 has a frame 210 that supports and encloses a power system 220 (represented in FIGS. 2-3 as a block, as the actual power system is enclosed within the frame 210). The powder system 220 includes an engine that provides a power output to a hydraulic system. The hydraulic system acts as a power conversion system that includes one or more hydraulic pumps for selectively providing pressurized hydraulic fluid to actuators that are operably coupled to work elements in response to signals provided by operator input devices. The hydraulic system also includes a control valve system that selectively provides pressurized hydraulic fluid to actuators in response to signals provided by operator input devices. The excavator 200 includes a plurality of work elements in the form of a first lift arm structure 230 and a second lift arm structure 330 (not all excavators have a second lift arm structure). In addition, excavator 200, being a work vehicle, includes a pair of tractive elements in the form of left and right track assemblies 240A and 240B, which are disposed on opposing sides of the frame 210.

[0054] An operator compartment 250 is defined in part by a cab 252, which is mounted on the frame 210. The cab 252 shown on excavator 200 is an enclosed structure, but other operatorAttorney Docket No.: B2023-0036-W01compartments need not be enclosed. For example, some excavators have a canopy that provides a roof but is not enclosed A control system, shown as block 260, is provided for controlling the various work elements. Control system 260 includes operator input devices, which interact with the power system 220 to selectively provide power signals to actuators to control work functions on the excavator 200. In some embodiments, the operator input devices include at least two two-axis operator input devices to which operator functions can be mapped.

[0055] Frame 210 includes an upper frame portion or house 211 that is pivotally mounted on a lower frame portion or undercarriage 212 via a swivel joint. The swivel joint includes a bearing, a ring gear, and a slew motor with a pinion gear (not pictured) that engages the ring gear to swivel the machine. The slew motor receives a power signal from the control system 260 to rotate the house 211 with respect to the undercarriage 212. House 211 is capable of unlimited rotation about a swivel axis 214 under power with respect to the undercarriage 212 in response to manipulation of an input device by an operator. Hydraulic conduits are fed through the swivel joint via a hydraulic swivel to provide pressurized hydraulic fluid to the tractive elements and one or more work elements such as lift arm 330 that are operably coupled to the undercarriage 212.

[0056] The first lift arm structure 230 is mounted to the house 211 via a swing mount 215. (Some excavators do not have a swing mount of the type described here.) The first lift arm structure 230 is a boom-arm lift arm of the type that is generally employed on excavators although certain features of this lift arm structure may be unique to the lift arm illustrated in FIGS. 2-3. The swing mount 215 includes a frame portion 215A and a lift arm portion 215B that is rotationally mounted to the frame portion 215A at a mounting frame pivot 231 A. A swing actuator 233 A is coupled to the house 211 and the lift arm portion 215B of the mount. Actuation of the swing actuator 233A causes the lift arm structure 230 to pivot or swing about an axis that extends longitudinally through the mounting frame pivot 231 A.

[0057] The first lift arm structure 230 includes a first portion 232, known generally as a boom, and a second portion 234, known as an arm or a dipper. The boom 232 is pivotally attached on a first end 232A to mount 215 at boom pivot mount 23 IB. A boom actuator 233B is attached to the mount 215 and the boom 232. Actuation of the boom actuator 233B causes the boom 232 to pivot about the boom pivot mount 23 IB, which effectively causes a second end 232B of the boom to be raised and low ered with respect to the house 211. A first end 234A of the arm 234 is pivotally attached to the second end 232B of the boom 232 at an arm mountAttorney Docket No.: B2023-0036-W01pivot 231C. An arm actuator 233C is attached to the boom 232 and the arm 234. Actuation of the arm actuator 233C causes the arm to pivot about the arm mount pivot 231C. Each of the swing actuator 233A, the boom actuator 233B, and the arm actuator 233C can be independently controlled in response to control signals from operator input devices.

[0058] An exemplary’ implement interface 270 is provided at a second end 234B of the arm 234. The implement interface 270 includes an implement carrier 272 that can accept and securing a variety of different implements to the lift arm 230. Such implements have a machine interface that is configured to be engaged with the implement carrier 272. The implement carrier 272 is pivotally mounted to the second end 234B of the arm 234. An implement carrier actuator 233D is operably coupled to the arm 234 and a linkage assembly 276. The linkage assembly includes a first link 276A and a second link 276B. The first link 276A is pivotally mounted to the arm 234 and the implement carrier actuator 233D. The second link 276B is pivotally mounted to the implement carrier 272 and the first link 276A. The linkage assembly 276 is provided to allow the implement carrier 272 to pivot about the arm 234 when the implement carrier actuator 233D is actuated.

[0059] The implement interface 270 also includes an implement power source (not shown in FIGS. 2-3) available for connection to an implement on the lift arm structure 230. The implement power source includes pressurized hydraulic fluid port to which an implement can be coupled. The pressurized hydraulic fluid port selectively provides pressurized hydraulic fluid for powering one or more functions or actuators on an implement. The implement power source can also include an electrical power source for powering electrical actuators or an electronic controller on an implement. The electrical power source can also include electrical conduits that are in communication with a data bus on the excavator 200 to allow communication between a controller on an implement and electronic devices on the excavator 200. It should be noted that the specific implement power source on excavator 200 does not include an electrical power source. However, in some configurations, the specific implement power source or other power sources of an excavator or other power machine can include an electrically powered actuator, for example, when the excavator is an electrically pow ered work vehicle that includes an electrical power storage device (e.g., a batten ). Correspondingly, control of actuators in some cases may not necessarily require control of hydraulic flow (e.g., may be accomplished via electronic control of an electronic actuator by a control device).Attorney Docket No.: B2023-0036-W01

[0060] The lower frame 212 supports and has atached to it a pair of tractive elements 240, identified in FIGS. 2-3 as left track drive assembly 240A and right track drive assembly 240B. Each of the tractive elements 240 has a track frame 242 that is coupled to the lower frame 212. The track frame 242 supports and is surrounded by an endless track 244, which rotates under power to propel the excavator 200 over a support surface. Various elements are coupled to or otherwise supported by the track 242 for engaging and supporting the track 244 and cause it to rotate about the track frame. For example, a sprocket 246 is supported by the track frame 242 and engages the endless track 244 to cause the endless track to rotate about the track frame. An idler 245 is held against the track 244 by a tensioner (not shown) to maintain proper tension on the track. The track frame 242 also supports a plurality of rollers 248, which engage the track and, through the track, the support surface to support and distribute the weight of the excavator 200. An upper track guide 249 is provided for providing tension on track 244 and preventing the track from rubbing on track frame 242.

[0061] A second, or lower, lift arm 330 is pivotally atached to the lower frame 212. A lower lift arm actuator 332 is pivotally coupled to the lower frame 212 at a first end 332A and to the lower lift arm 330 at a second end 332B. The lower lift arm 330 is configured to carry a lower implement 334, which in one embodiment is a blade as is shown in FIGS. 2-3. The lower implement 334 can be rigidly fixed to the lower lift arm 330 such that it is integral to the lift arm. Alternatively, the lower implement can be pivotally atached to the lower lift arm via an implement interface, which in some embodiments can include an implement carrier of the type described above. Lower lift arms with implement interfaces can accept and secure various different types of implements thereto. Actuation of the lower lift arm actuator 332, in response to operator input, causes the lower lift arm 330 to pivot with respect to the lower frame 212, thereby raising and lowering the low er implement 334.

[0062] Upper frame portion 211 supports cab 252, which defines, at least in part, operator compartment or station 250. A seat 254 is provided within cab 252 in which an operator can be seated while operating the excavator. While siting in the seat 254, an operator will have access to a plurality of operator input devices 256 that the operator can manipulate to control various work functions, such as manipulating the lift arm 230, the lower lift arm 330, or the tractive elements 240, pivoting the house 211. the tractive elements 240, and so forth.

[0063] Excavator 200 provides a variety of different operator input devices 256 to control various functions. For example, hydraulic joysticks are provided to control the lift arm 230 andAttorney Docket No.: B2023-0036-W01swiveling of the house 211 of the excavator. Foot pedals with attached levers are provided for controlling travel and lift arm swing. Electrical switches are located on the joysticks for controlling the providing of power to an implement attached to the implement carrier 272. Other types of operator inputs that can be used in excavator 200 and other excavators and power machines include, but are not limited to, switches, buttons, knobs, levers, variable sliders, and the like. The specific control examples provided above are exemplary in nature and not intended to describe the input devices for all excavators and what they control.

[0064] Display devices are provided in the cab to give indications of information relatable to the operation of the power machines in a form that can be sensed by an operator, such as, for example audible or visual indications. Audible indications can be made in the form of buzzers, bells, and the like or via verbal communication. Visual indications can be made in the form of graphs, lights, icons, gauges, alphanumeric characters, and the like. Displays can provide dedicated indications, such as warning lights or gauges, or dynamic to provide programmable information, including programmable display devices such as monitors of various sizes and capabilities. Display devices can provide diagnostic information, troubleshooting information, instructional information, and various other types of information that assists an operator with operation of the power machine or an implement coupled to the power machine. Other information that may be useful for an operator can also be provided.

[0065] The description of power machine 100 and excavator 200 above is provided for illustrative purposes, to provide illustrative environments on which the embodiments discussed below can be practiced. While the embodiments discussed can be practiced on a power machine such as is generally described by the power machine 100 shown in the block diagram of FIG.1 and more particularly on an excavator such as excavator 200, unless otherwise noted, the concepts discussed below are not intended to be limited in their application to the environments specifically described above.

[0066] In some embodiments, sensors of other known types can be arranged to measure parameters relating to a current orientation of a workgroup or other system of a power machine, including to measure angular orientations of various components of a lift arm. For example, as shown in FIG. 3, the excavator 200 can include angle sensors 235, 237. 239 each of which can determine the relative orientation of specific components of the work group of the excavator 200. For example, the angle sensor 235 can be coupled to the swing mount 215 at the boom pivot mount 23 IB and can sense the angle between the swing mount 215 and the boom 232Attorney Docket No.: B2023-0036-W01(e.g., relative to a line parallel to the end 232A of the boom 232). As another example, the angle sensor 237 can be coupled to the boom 232 at the arm mount pivot 231C and can sense the angle between the boom 232 (e.g., relative to a line parallel to the end 232B of the boom 232) and the arm 234 (e.g., relative to a line parallel to the end 234A of the arm 234). As yet another example, the angle sensor 239 can be coupled to the arm 234 at an implement interface pivot mount 231D and can sense the angle between the arm 234 (e.g.. relative to a line parallel to the end 234B of the arm 234) and the implement earner 272 (e.g., relative to a line parallel to a cutting angle of a bucket (not shown) secured to the implement carrier 272).

[0067] Referring also to FIG. 2, the excavator 200 can also include angle sensors 241, 243. The angle sensor 241 can be coupled to the swing mount 215 at the mounting frame pivot 231 A and can sense the angle between the frame portion 215A and the swing mount 215 to sense a boom offset angle for the excavator 200 (i.e., to indicate rotation of the lift arm 230 about an offset axis that is parallel to the axis 214 relative to the house 211). The angle sensor 243, which is obstructed from view in FIGS. 2 and 3, can be coupled to the undercarriage 212 (or the house 211) and can sense the angle between the house 211 and the undercarriage 212. In some cases, this angle can be considered the slew angle for the excavator 200 (i.e., the rotational position of the excavator about axis 214, relative to a neutral location).

[0068] As further discussed below, signals from the angle sensors 235, 237, 239, 241, 243 can be processed in known ways to determine a current orientation of the implement carrier 272 or other components relative to a reference frame (e.g., a fixed frame defined by undercarriage 212. In some cases, orientation of a particular component can be determined from the perspective of the excavator 200 in isolation. In some cases, orientation of a particular component can be determined relative to a surrounding environment. For example, based on a known position of the excavator 200 in an environment, and known dimensions of the undercarriage 212, the track drive assemblies 240A, 240B, and other excavator components, signals from the angle sensors 235, 237, 239, 241. 243 can be analyzed to specify a position of any part of the lift arm 230 relative to the environment.

[0069] In different embodiments, the angle sensors 235, 237, 239, 241, 243 can be implemented in different ways. For example, each angle sensor 235. 237, 239, 241. 243, can be a hall-effect sensor, a torque sensor, an accelerometer, a rotary encoder, etc. Further, in some cases, non-rotational sensors can be used. For example, data from linear displacement or other position sensors (not shown) on various actuators for the lift arm 230 can be used inAttorney Docket No.: B2023-0036-W01combination with known dimensions of the excavator 200 to specify relevant triangular identities for the lift arm 230 and thereby also indicate the angular orientation of particular components and the relative (or absolute) orientation of any particular part of the lift arm 230. Regardless of the specific sensor configuration, however, various known kinematic approaches can be used to determine a current orientation of any particular lift arm (or other) component based on measurements from the angle sensors 235, 237, 239, 241, 243 (or others, including sensors (not shown) for the lower lift arm 330) and known geometries of relevant one or more relevant components (e.g., the boom 232, the arm 234, the implement interface 270, an implement coupled to the implement interface 270, the frame portion 215A, the house 211, a distance between the sensors 241, 243, etc.).

[0070] FIG. 4 shows a schematic illustration of a control system 400 for an excavator (or other power machine), as can be implemented as a specific example of the control system 160 (see FIG. 1), or a portion thereof. The control system 400 can include one or more operator input devices 402, a hydraulic (or other actuation) system 403, and a control device 408. The operator input devices 402 can be implemented in different ways, including as one or more joysticks, one or more pedals, or other known types of devices for receiving input from operators for control of components of a power machine.

[0071] In one embodiment, as shown in FIG. 4, the operator input devices 402 can include joysticks 404, 406. Each joystick 404, 406 can be located within a cab of the excavator (e.g., the cab 252 of FIG. 3), and each can be pivoted about at least tw o axes to adjust a current respective position of the joystick 404, 406. Each joystick 404, 406 can include a respective orientation sensor 412. 414, which can sense the current orientation of each joystick 404, 406 relative to a pivot point of the respective joystick 404, 406. For example, the orientation sensor 412 can sense the orientation of the joystick 404 relative to a neutral position (or pivot point) of the joystick 404, while the orientation sensor 414 can sense the orientation of the joystick relative to a neutral position (or pivot point) of the joystick 406. The orientation sensors 412, 414 can each be in communication with the control device 408 and can each be implemented in a variety of known ways. For accelerometer, a magnetometer (e.g., one or more Hall-effect sensors), an inertial measurement unit ("IMU"). etc. Thus, regardless of the configuration, the control device 408 can be configured to receive a signal from each orientation sensor 412, 414 (or the joysticks 404, 406, generally), to indicate a current orientation of each joystick 404, 406.Attorney Docket No.: B2023-0036-W01

[0072] As further detailed below, the orientation of the joysticks 404, 406 can generally correspond to operator inputs for particular power machine operations, which can then be converted to commands for actuators by the control device 408. For example, in some embodiments, the spatial orientation of either of the joysticks 404, 406 can correspond to a particular ty pe and intensity of commanded movement. For example, a region of all possible positions for a two-axis joystick can be segmented into one or more regions (e.g., four quadrants arranged around an origin), which can correspond to a particular task for the excavator. In particular, when the control device receives, from the corresponding orientation sensor, that the joystick is within a particular region, then the control device can implement the task associated with the particular region (e.g., driving forward). In addition, movement of the joystick towards or away a neutral position of the joystick while the joystick is positioned within the particular region can adjust a property related to the task associated with the particular region. For example, further movement of the joystick away from the neutral position can correspond to a commanded increase in speed of a relevant movement, while further movement of the joystick towards the neutral position can correspond to a commanded decrease in speed, including when the task associated with the particular region is driving forward. As further detailed below, in some cases, the control system 400 can allow customization of which particular operation is associated with which orientation(s) of the joysticks 404, 406 or other operator input device(s), as well as the characteristics (e.g., speed, maximum or minimum values, etc.) of the commanded operation.

[0073] In some embodiments, operator input devices 402 can include one or more actuatable buttons or other operator input devices that can have one or more corresponding positions. Some of these operator input devices can be integrated into handles for joysticks 404, 406. For example, an actuatable button can be a single pole switch (e.g., a trigger, a rocker switch, etc.) that has two corresponding positions, with a first position indicating the trigger being off, and with a second position indicating the trigger being on. As another example, an actuatable button can be a double pole double throw switch having two actuated positions. As yet another example, an actuatable button can be a push-button having two positions (e.g., on - actuated, and off - not actuated). As another example, an actuatable button can be a double push button. In some cases, an operator input device can include other operator input devices including a roller sensor, a toggle sensor, a joystick, etc., each of which can have more than three positions, including a plurality of intermediate positions. Thus, generally, an operator input device can provide commands for power machine operations via bulk movement of theAttorney Docket No.: B2023-0036-W01operator input device (e.g., movement of the joysticks 404, 406) or via actuation of buttons on any of the operator input devices 402 (e.g., movement of switches, push-buttons, rollers, etc.). (As used herein, “button” is intended also to include virtual icons or other virtual interfaces that can receive input similar to mechanical buttons).

[0074] Regardless of the configuration, the actuatable buttons (or other input mechanisms) integrated into the handle of either joystick 404, 406 can be in communication with the control device 408. In this way, the control device 408 can receive an indication that a particular actuatable button (or other mechanism) has been, or has not been, actuated. Similar to the orientation of the joysticks 404, 406, some or all of the actuatable buttons can be mapped to corresponding actuators or functions of the excavator. In some cases, as also generally noted above, buttons on the joysticks 404, 406 can correspond to operation of particular actuators. In some cases, buttons on the joysticks 404, 406 can correspond to adjustments to the control system 400 itself. For example, in some cases, actuatable buttons integrated into the handle associated with the joystick 404 can adjust an operational mode or control mode of a power machine, including to specifically indicate particular control modes, cycle through a sequence of control modes, or adjust parameters of a particular control mode. In some cases, as described in more detail below, a particular control mode can correspond to a particular control-function mapping of the operator input devices 402, or components thereof, to particular commands (e.g., commands for particular actuators, commands to adjust system response or other operational parameters, etc.). In some cases, each control mode for the control system 400 can correspond to a different mapping of functionality to the one or more input devices 402, so that the one or more input devices 402 can control a power machine differently , depending on the currently selected mode.

[0075] In some embodiments, the operator input devices 402 can include pedals 416, 418 each having a respective position sensor 420, 422 that can sense the direction of movement of the corresponding pedal (e.g.. forwards or backwards) and the amount of movement of the pedal from a neutral position. In some cases, the position sensors 420, 422 can be implemented in a similar manner as the previously described orientation sensors. For example, each position sensor 420, 422 can be a hall-effect sensor, an optical sensor, etc. In some embodiments, and similarly to the joysticks 404. 406, the pedals 416, 418 can be programmable and assigned different functions for each direction. For example, the pedal 416 moving forwards from a neutral orientation can be assigned with a first function, while the pedal 416 moving backwardsAttorney Docket No.: B2023-0036-W01from the neutral orientation can be assigned with a second function different from the first function. Further, as with other input devices discussed herein different control-function mapping for the pedals 416, 418 can be assigned for different control modes.

[0076] As shown in FIG. 4, the operator input devices 402 are physically decoupled from the hydraulic system 403. Thus, adjustment of the orientation (or actuation of a mechanical button of an operator input device) of the operator input devices 402 does not directly adjust the operation of the hydraulic system 403 or of the actuators of the hydraulic system 403. Rather, operator inputs are received by the control device 408, modified as appropriate, and then transmitted to the hydraulic system 403 to control movement of an actuator. In this regard, for example, the hydraulic system 403 can include actuators 424, 426. 428 that have respective actuatable valves 430, 432, 434 to control operation of the actuators 424, 426, 428. Each of the valves 430, 432, 434 can be in communication with the control device 408 and can be in fluid communication with the respective actuator 424, 426, 428. Thus, the control device 408 can adjust a position of each actuatable valve 430, 432, 434 (e.g., by providing electrical signals to each actuatable valve 430, 432, 434), and thereby control hydraulic flow to the respective actuators 424, 426, 428 to control movement of the actuators 424, 426, 428 (e.g., to extend the actuator, to retract the actuator, to rotate the actuator, etc.). In other embodiments, however, other known devices can be used to control operation of other known actuators, based on signals from the control device 408 that are, in turn, based on signals from the operator input devices 402. In some embodiments, the actuatable valves 430, 432, 434 are control valves that control a spool valve, which in turn provides hydraulic flow to the respective actuators 424, 426, 428. While three actuators are shown for illustrative purposes, in various embodiments the total number of actuators may be more than three actuators.

[0077] As generally discussed above, in different embodiments, power machine actuators can be implemented in different ways. For example, one or more of the actuators 424, 426, 428 can be a swing actuator (e.g., similar to the swing actuator 233A of FIG. 2). a boom actuator (e.g., similar to the boom actuator 233B of FIG. 2), an arm actuator (e.g., similar to the arm actuator 233C of FIG. 2), an implement carrier actuator (e.g., the similar to implement carrier actuator 233D), an auxiliary actuator (e.g., an actuator for a lifting clamp), a slew' motor (or in other words a slew actuator) for a swivel joint (e.g., the slew motor that rotates upper frame portion 211 relative to the undercarriage 212), a drive assembly for a tractive element (e.g., the track drive assembly 240A), or otherwise. Thus, generally, each of the actuators 424, 426, 428Attorney Docket No.: B2023-0036-W01can be a linear actuator (e.g., that extends and retracts), a rotational actuator, or other actuators of known types.

[0078] The actuatable valves 430, 432, 434 can also be implemented in different ways. For example, each actuatable valve 430, 432, 434 can be an electrically controlled valve including a solenoid valve, a pilot solenoid valve, etc. In this way, when a control device 408 electrically powers the electrically controlled valve (e.g., according to a command output value), the valve position changes to adjust the flow of hydraulic fluid through the electrically controlled valve thereby adjusting the hydraulic flow to a respective actuator. In other implementations, however, other known valve types or other known mechanisms for control of actuators can be used.

[0079] While three actuators 424, 426, 428 are illustrated in FIG. 4, in other configurations the control system 400 can have other numbers of actuators (e.g., one, two, four, five, etc.). In addition, while each of the actuators 424, 426, 428 are illustrated as having, or being in fluid communication with, a respective actuatable valve 430, 432, 434 other configurations are possible. For example, one actuatable valve can be in fluid communication with multiple actuators, or multiple actuatable valves can be in fluid communication with one actuator. In this way, adjusting the valve position of one actuatable valve can sometimes control movement of the multiple actuators, and adjusting the valve position of multiple actuatable valves can sometimes control movement of a single actuator.

[0080] Generally, the control device 408 can be implemented in a variety of different ways. For example, the control device 408 can be implemented as known types of processor devices, (e.g., microcontrollers, field-programmable gate arrays, programmable logic controllers, logic gates, etc.), including as general or special purpose computers. In addition, the control device 408 can also include other computing components, such as memory, inputs, other output devices, etc. (not shown). In this regard, the control device 408 can be configured to implement some or all of the steps of the processes described herein, as appropriate, which can be retrieved from memory. In some embodiments, the control device 408 can include multiple control devices (or modules) that can be integrated into a single component or arranged as multiple separate components. In some embodiments, the control device 408 can be part of a larger control system (e.g., the control system 160 of FIG. 1) and can accordingly include or be in electronic communication with a variety of control modules, including hub controllers, engine controllers, drive controllers, and so on.Attorney Docket No.: B2023-0036-W01

[0081] FIG. 5 illustrates a hydraulic system 500 that can be implemented on a power machine such as the power machine 100 of FIG. I. the excavator 200 of FIGS. 2-4, or other power machines (e.g., other excavators). For example, the hydraulic system 500 can be incorporated into a power machine that includes an internal combustion engine, an electric power source, or a combination of different types of power sources, known generally as hybrid power sources.

[0082] In the illustrated example, the hydraulic system 500 can include a supply system 510 that provides pressurized hydraulic fluid for operation of one or more hydraulic actuators. For example, the supply system 510 can include one or more pumps of various generally known configurations that are powered by a corresponding power source (e.g.. engine or electric motor) to supply a flow of hydraulic fluid to downstream components and sub-systems of the hydraulic system 500. In different cases, the supply system 510 can include a fixed displacement pump or a variable displacement pump, with the pump powered by an electric motor (e.g., directly), an internal combustion engine (e.g., directly), or other source of rotational power.

[0083] Generally, the supply system 510 can provide the flow' of hydraulic fluid at desired flow conditions, e.g., at a commanded flowrate, according to demands of the hydraulic system 500. In some examples, for a predetermined pump speed or a range of pump speeds, variable displacement pumps may be operated at different displacements to provide different flow rates. In some cases, the supply system 510 can adapt to changes in flow7demand of the hydraulic system 500 by changing a (rotational) speed of a motor or other rotational power source and thereby changing the (rotational) speed of a supply pump.

[0084] In some embodiments, an electronic control unit can be provided to electronically control settings of devices of the hydraulic system 500 or receive user commands. For example, the hydraulic system 500 can be an implementation of the hydraulic system 403 and implementations of the control device 408 can correspondingly provide electronic (or other) control of various valves or other components of the hydraulic system 500. For example, the control device 408 can operate to electronically control operation of the supply system 510 or other sub-systems of the hydraulic system 500, including based on operator input or according to particular automated control operations (e.g., as further discussed below).Attorney Docket No.: B2023-0036-W01

[0085] Continuing, a valve system 520 can be provided to control a flow of hydraulic fluid for operation of hydraulic actuators. In the illustrated example, the valve system 520 can include a first valve (sub)system 522 that is in communication with first and second ports in a first actuator 530 and a second valve (sub)system 524 that is in communication with first and second ports in a second actuator 532. In some cases, the first valve system 522 and the second valve system 524 can include or be configured to interoperate with various sensors (e.g., a pressure sensor) to control the flow or pressure of hydraulic fluid into or out of the first actuator 530 or the second actuator 532. Generally, a flow of hydraulic fluid from the supply system 510 can be selectively routed by the valve systems 522, 524, from the supply system 510 to the first actuator 530 and the second actuator 532, respectively, based on demands of corresponding work operations or corresponding user inputs (e.g., as implemented via the control device 408).

[0086] The first actuator 530 and the second actuator 532 can be workgroup actuators that receive or discharge a flow of hydraulic fluid to operate a work element and thereby perform various tasks for a power machine. For example, the workgroup actuators of an excavator can include a boom cylinder, an arm cylinder, or a bucket cylinder that can be used individually or collectively to lift, dig, or load material. Thus, for example, the first actuator 530 can be an arm actuator (e.g., the actuator 233C) and the second actuator 532 can be a boom actuator (e.g., the actuator 233B), although a variety of other configurations are possible. While the hydraulic system 500 includes two actuators, a hydraulic system can include a smaller or a greater number of actuators in other examples.

[0087] Continuing, an energy recovers- system 540 can be provided downstream of the first valve system 522 and the second valve system 524 (e.g., between the valve systems 522, 524 and tank). Correspondingly, an outflow of hydraulic fluid from the first actuator 530 and the second actuator 532 can be selectively routed through the energy recovery system 540 to recover energy from the hydraulic fluid before the fluid is returned to tank. For example, the energy recovery system 540 can include one or more valves that can selectively direct the outflow of hydraulic fluid to tank (e.g., a reservoir at atmospheric pressure) or an energy storage device that can capture energy from the hydraulic fluid (e.g., via storage of pressurized fluid). In some examples, the recovered energy can then be reutilized to support further operation of the hydraulic system 500 (e.g., for further workgroup functions) or of other systems of a power machine.Attorney Docket No.: B2023-0036-W01

[0088] In some examples, an outflow from the energy storage device or the energy recovery system 540 can be routed to the supply system 510. For example, when the hydraulic system 500 requires an increased flow of hydraulic fluid, the supply system 510 can receive hydraulic fluid at from the energy recovery system 540 (e.g., and thereby satisfy the demands of the actuators 530, 532). Or energy7from the energy7recovery7system 540 can be otherw ise used to boost the power of the supply system 510. Accordingly, the energy recovery system 540 can assist in supplying hydraulic fluid to hydraulic actuators with greater flexibility and controllability, as well as in overall improvement of power machine efficiency.

[0089] As noted above, different implementations of the hydraulic system 500 can include different numbers of actuators, or valve systems. Correspondingly, different implementations can include the energy recovery system 540 arranged to receive flow from various configurations or one or more actuators (or one or more valve systems). Similarly, multiple energy recovery sy stems 540 can be included, in some examples, dedicated to particular one or more actuators (or one or more valve systems).

[0090] Particular examples of the supply system 510, the valves systems 522, 524, the actuators 530, 532, and the energy7recovery system 540 are presented below, including with particularly beneficial inter-arrangement of the various systems and actuators for some implementations. However, a variety of other approaches are possible under the disclosed technology. For example, a wide range of known valve systems, supply systems, or actuators can be employed with the various examples of the energy recovery system 540 presented below or otherwise disclosed herein.

[0091] FIGS. 6A and 6B illustrate an example hydraulic system 600 and an energy recovery system 640, which are particular examples of the hydraulic system 500 and the energy recovery system 540 of FIG. 5. To that end, features of the hydraulic system 600 and the energy recovery system 640 described below include reference numbers that are generally similar to those used in FIG. 5, and discussion above applies to similar named or numbered items below, unless otherwise noted or required. For example, the hydraulic system 600 includes a supply system 610, a valve system 620, and an actuator 630, just as the hydraulic system 500 includes the supply system 510, the valve system 520. and the actuator 530. For convenience, the systems 610, 620, 630 are illustrated together in FIGS. 6A and 6B, but may be implemented independently in some cases. Further, absent contrary indication, the principles discussed below7, for this and other embodiments, are not limited to single-actuator systems.Attorney Docket No.: B2023-0036-W01

[0092] In the illustrated example, the energy recovery system 640 of the hydraulic system 600 includes an energy (e.g.. pressure) storage system, an upstream valve arrangement to control flow into the pressure storage system, and a downstream valve arrangement to control flow out of the pressure storage system to the systems 610, 620, 630. A variety of valve arrangements may be implemented in this regard, including as may implement particular control logic discussed below.

[0093] In particular, in the illustrated example, the energy recovery system 640 includes a proportional valve 642 and a relief valve 644 that are in communication with the hydraulic actuators 630 of the valve system 620. The proportional valve 642 and the relief valve 644 are arranged in parallel relative to an outlet flow from hydraulic actuators. The relief valve 644 and the proportional valve 642 can be independently controlled via separate solenoids or other control mechanisms. Thus, the proportional valve 642 and the relief valve 644 may open sequentially or simultaneously and by varying relative degrees. Accordingly, backpressure of the hydraulic fluid and flow for energy can be efficiently controlled for a variety of operations.

[0094] In particular, the proportional valve 642 can provide a variable-size orifice to control back-pressure at an outlet of a hydraulic actuator. For example, as shown, the proportional valve 642 can be a 2-way discharge valve that is movable between positions to selectively permit an outflow from the hydraulic actuator 630 to flow across the proportional valve 642 to tank 660 (e.g., a reservoir). With the valve 642 at varying degrees of open, the size of the corresponding orifice can dictate a corresponding particular pressure drop for flow received from the actuator 630 (or the supply or valve systems 610, 620) and thus provide control over backpressure seen by the actuator 630. In contrast, by fully closing an orifice of the proportional valve 642, the outflow from the hydraulic actuator may not be permitted to flow across the proportional valve 642 to tank 660. Thus, pressure at an inlet to the energy recovery system 640 may build (while the proportional valve 642 is closed), until high enough to reach the set pressure of the pressure relief valve 644 and thus flow through the valve 644.

[0095] In this regard, the relief valve 644 can control an outflow of hydraulic fluid from the hydraulic actuator 630 to an energy storage device 650, so that pressure energy of the hydraulic fluid can be captured for later use (e.g., rather than simply being directed to tank). Correspondingly, in some cases, the energy storage device 650 can be sized based on duty cycle data of the hydraulic system 600. In the illustrated example, the relief valve 644 is an electro-proportional relief valve, although differently controlled relief valves are possible inAttorney Docket No.: B2023-0036-W01different embodiments. Similarly, as illustrated, an opening area of an orifice of the relief valve 644 can be partly controlled based on a pilot signal pressure difference between an inlet of the relief valve 644 and the energy storage device 650.

[0096] While the energy storage device 650 is illustrated as an accumulator, the energy¬ storage device can be a battery, a supercapacitor, or a flywheel that can store various forms of energy including compressed air, electricity, or kinetic energy in different examples. As illustrated, however, the relief valve 644 can provide hydraulic fluid to the energy storage device 650, at a desired pressure, hydraulic fluid received from the actuator 630 into the energyrecovery system 640 - provided that the proportional valve 642 is controlled to correspondingly restrict (e.g., block) flow through the valve 642 to tank. Correspondingly, fluid of appropriately high pressure can be selectively routed from the outflow of an actuator to an accumulator (or other storage) device, for later use. In some examples, particular control logic can be employed for the valve 642, as further detailed below.

[0097] In other examples, other valve arrangements can be implemented to provide similar selective control over flow routing and orifice size as discussed above (and further below). However, in some cases, the use of two separately movable valves (e.g., a proportional valve and a relief valve for pressure control) can provide particular advantages for operation of energy recovery systems for hydraulic actuators (e.g., the actuator 630). For example, approaches that implement three-way selector valves relative to tank and an energy^ recovery device may sometimes require additional valves - and corresponding control - to independently regulate back pressure at separate ports of the actuator. Further, a three-way proportional selector valve may not be readily available for installation or require precise area characteristics of the valve for back pressure regulation at the ports of the actuator.

[0098] Continuing, a control valve 652 can be provided between the energy storage device 650 and the supply system 610. As shown, the control valve 652 can be (electronically) controlled to selectively permit or block a flow of hydraulic fluid from the energy storage device 650 to an inlet of the supply system 610. For example, the control valve 652 can be controlled to block a flow path from the energy storage device 650 to the supply system 610, so that the energy- storage device 650 can be charged to a desired capacity. Further, the control valve 652 can be controlled to open, based on the demands of the supply system 610 or the valve system 620, to direct a flow of hydraulic fluid from the energy storage device 650 to the supply system 610.Attorney Docket No.: B2023-0036-W01

[0099] In particular, the example configuration of FIG. 6A provides a direct flow of hydraulic fluid from the energy storage device 650 into the supply system 610 and thus on to the valve system 620. For example, flow from the energy storage device 650 can directly feed an inlet to a pump of the supply system 610 (e.g., as further discussed below). In some such cases, fluid from the tank 660 can be supplied to the supply system 610 when the control valve 652 is closed. Thus, for example, an elevated initial pressure to the supply system 610 can be provided, as needed for a particular workgroup (or other) operation.

[0100] In some examples, flow of hydraulic fluid from the energy storage device 650 can be used to indirectly boost power of a supply system 610, e.g., without directly providing additional flow as discussed for FIG. 6A. For example, with specific reference to FIG. 6B, a hydraulic motor 670 can be provided in operational communication with a pump of the supply system 610, so that power from the motor 670 can assist in powdering the pump. For example, the hydraulic motor 670 can be mechanically (e.g., directly) coupled to a shaft of a pump of the supply system 610 to provide assistive rotational power to the supply system 610 when the motor 670 is rotated by a hydraulic flow. In some such cases, the hydraulic motor 670 can be a four-quadrant pump that operates as a pump and a motor in bi-directional rotational directions and can be configured to operate at appropriately high pressure. Thus, generally, the hydraulic motor 670 can be powered by a discharge of hydraulic fluid from the energy storage device 650 to tank 660 and can thus provide boost power to the supply system 610. In some cases, the hydraulic motor 670 can operate in an idle mode (e g., a pumping mode) when there is no flow from the energy storage device 650. In some cases, a one-way valve can be provided to ensure sufficient supply at an upstream side of the motor 670 (relative to tank), regardless of flow from the energy storage device 650.

[0101] FIGS. 7A and 7B illustrate an example hydraulic system 700 and an energy recovery system 740, which are particular examples of the hydraulic system 500 and the energy recovery system 540 of FIG. 5, and alternatively configurations of the hydraulic system 600 and the energy recovery system 640 of FIGS. 6A and 6B. To that end, features of the hydraulic system 700 and the energy recovery' system 740 described below include reference numbers that are generally similar to those used in FIGS 5-6B, and discussion of above applies to similar named or numbered items below unless, otherwise noted or required. For example, the hydraulic system 700 includes a supply system 710, a valve system 720, and an actuator 730, just as the hydraulic system 600 includes the supply system 610 and the valve system 620. ForAttorney Docket No.: B2023-0036-W01convenience, the systems 710, 720, 730 are illustrated together in FIGS. 7A and 7B, but may be implemented independently in some cases. Further, absent contrary indication, the principles discussed below, for this and other embodiments, are not limited to single-actuator systems.

[0102] In some aspects, the hydraulic system 700 and the energy’ recovery’ system 740 differ from the hydraulic system 600 and the energy recovery system 640. For example, FIGS.7A and 7B show the energy recovery system including a proportional valve 742 and a selector valve 744 that are arranged in series relative to an outlet flow from the actuator 730. Similar to the valve 642, the proportional valve 742 can be a 2-way proportional valve that moves between open and closed positions. For example, in the open position, the proportional valve 742 can permit an outflow from a hydraulic actuator to flow through the proportional valve 742 and to the selector valve 744. In the closed position, the proportional valve 742 may block the outflow from the hydraulic actuator from flowing to the selector valve 744. Thus, as also similarly described above, a change in orifice size across the proportional valve 742 as the valve 742 moves between the open and closed positions can indirectly control a pressure of hydraulic fluid at an outlet of the hydraulic actuator 730.

[0103] Continuing, the selector valve 744 can be a 3-way valve that moves between a first position that routes the fluid flow from the proportional valve 742 to tank 760 and a second position that routes the fluid flow from the proportional valve 742 to an energy’ storage device 750. Thus, the selector valve 744 and the proportional valve 742 can be controlled together to selectively route outflow from the actuator 730 to tank 760 or to the energy storage device 750 (e.g.. a hydraulic accumulator).

[0104] In some examples, the selector valve 744 can be a simple two-position valve, controlled by on-off solenoid or other similar control device. In some examples, the selector valve 744 can be operated to provide a variable orifice for flow from the proportional valve 742. Thus, in some cases, the variable orifice of the selector valve 744 can be controlled to regulate backpressure at the hydraulic actuator of the hydraulic system 700.

[0105] To provide additional energy to the supply or valve systems 720. 730, a control valve 752 can route the flow of hydraulic fluid from the energy’ storage device 750 to the supply system 710. In various examples, as also discussed above, the hydraulic flow from the energy storage device 750 can thus be used to provide boost flow to the supply or valve systems 720,Attorney Docket No.: B2023-0036-W01730 (see, e.g., FIG. 7A) or to provide boost rotational power (see, e.g., FIG. 7B). Or, as with other examples herein, the stored energy from the energy storage device 750 can be otherwise employed. Further, as shown in FIG. 7B, a hydraulic motor 770 can be provided at an inlet (e.g., via a shaft) of the supply system 710 between the control valve 752 and the supply system 710 to provide assistive rotational power.

[0106] FIGS. 8A and 8B illustrate an example hydraulic system 800 and an energy recovery system 840, which are particular examples of the hydraulic system 500 and the energy recovery' system 540 of FIG. 5, and alternatively configurations of the hydraulic system 600 and the energy recovery system 640 of FIGS. 6A and 6B and the hydraulic system 700 and the energy recovery system 740 of FIGS. 7A and 7B. To that end. features of the hydraulic system 800 and the energy' recovery' system 840 described below include reference numbers that are generally similar to those used in FIGS 5-7B, and discussion of above applies to similar numbers below unless otherwise noted or required. For example, the hydraulic system 800 includes a supply system 810 and a valve system 820, just as the hydraulic system 600 includes the supply system 610 and the valve system 620. For convenience, the systems 810, 820, 830 are illustrated together in FIGS. 8A and 8B, but may' be implemented independently in some cases. Further, absent contrary' indication, the principles discussed below, for this and other embodiments, are not limited to single-actuator systems.

[0107] In some aspects, the hydraulic system 800 differ from the hydraulic system 600 or the hydraulic system 700. For example, FIGS. 8A and 8B show the energy recovery system 840 including a three-way proportional valve 842. The proportional valve 842 can discretely move between positions to control pressure and outflow from hydraulic actuators of the hydraulic system 800. For example, in a first position, an orifice of the proportional valve 842 can be fully open to discharge an outflow from hydraulic actuators to tank 860 with small to no throttle losses (e.g., as suitable for resistive operations). In a second position, the outflow from hydraulic actuators can be routed through a variable orifice of the proportional valve 842, for example, to control backpressure in the hydraulic actuators (e.g., for overrunning operations). In a third position, the outflow from hydraulic actuators can be directed to an energy storage device 850 to store excess energy during operation of the hydraulic actuators (e.g., during select operating conditions, as further detailed below). Correspondingly, in some cases, separate selector valves may be included in the valve system 820, to selectively route one or another port of the actuator 830 to the energy recovery system 840.Attorney Docket No.: B2023-0036-W01

[0108] In other regards, the hydraulic system 800 may operate similarly to the hydraulic systems 600. 700 as discussed above, including with regard to a control valve 852 to provide hydraulic fluid to the supply or valve systems 810, 820. Further, as shown in FIG. 8B, a hydraulic motor 870 can be provided at an inlet of the supply system 810 between the control valve 852 and the supply system 810 to provide assistive rotational power.

[0109] FIG. 9 illustrates an example hydraulic operation method 900 using a hydraulic system such as the hydraulic system 500, the hydraulic system 600, the hydraulic system 700, or the hydraulic system 800, although other types of hydraulic systems can be used. The method 900 generally refers to FIGS. 6A and 6B for brevity, but other hydraulic systems can be implemented to carry out the method 900. Although the flowchart illustrates blocks sequentially and in a particular order, in some examples, at least one or more blocks are executed at least partially in parallel, in another order, or bypassed.

[0110] Generally, under the method 900, an outflow from the actuator (e.g., a highest-load actuator) can be controllably routed according to a working mode of an actuator, to selectively route pressurized flow from the actuator to tank (e.g., with a particular pressure drop) or from the actuator to an energy recovery device (e.g., accumulator). For example, for multi-actuator systems, pressure signals may be used to determine a highest-load actuator (i.e., an actuator, of an active set of actuators, that is presently operating at the highest pressure) and whether an actuator is in a resistive or an overrunning mode, and flow from the actuator can then be routed accordingly either to tank or to an energy recovery device.

[0111] At block 902, whether a particular hydraulic actuator is a highest-load actuator of the hydraulic system can be determined. For example, the hydraulic system can include a plurality of actuators (e.g., a boom cylinder, an arm cylinder, a bucket cylinder, etc.) that operates different workgroup functions and can accordingly operate simultaneously at different pressures. In some cases, particular control of flow from the actuator may depend upon determining that the actuator is the highest-load actuator, e.g., relative to directing an outflow from the actuator to an energy recovery device as further detailed below. For example, for actuators that are not the highest-load actuator, the method may instead proceed to block 910 (as detailed below), for diversion of outflow to an energy storage device or to tank (e.g.. with selective restriction, as further detailed below).Attorney Docket No.: B2023-0036-W01

[0112] At block 904, a working mode of a hydraulic actuator can be determined (e.g., based on pressure data from the hydraulic actuator). For example, a pressure signal from the hydraulic actuator via a signal line or sensor may indicate that the hydraulic actuator is operating in an overrunning mode or a resistive mode (e.g., based on the relative motion of the hydraulic actuator and the pressure loading). In some cases, as also detailed below, a working mode of an actuator that is not a highest-load actuator may also be evaluated at block 904 (e.g., to determine whether to route outflow to tank with a particular orifice size, as further detailed below)

[0113] In some cases, for a highest-load actuator operating in a resistive mode, one or more recovery system valves (e.g., the proportional valve 642) can be controlled to open a path to tank 660 at block 906. Thus, for example, the energy recovery system may not increase the loading on the hydraulic system overall, and maximum power may be available for the commanded workgroup operation.

[0114] In contrast, at block 910, for a highest-load actuator operating in an overrunning mode (or for other actuators, as detailed below) the method 900 can include determining whether the outflow from the actuator can be diverted to the energy storage device 650 (e.g., an accumulator). For example, routing of flow to the energy storage device 650 can be controlled based on whether the energy storage device 650 may be at a maximum capacity, or have a remaining volume to receive pressurized hydraulic fluid. Further, routing of flow to the energy storage device 650 can be controlled based on whether the pressure of the outflow from an actuator may be sufficient to charge the energy storage device 650 (e.g., without causing an unwanted deviation from pump pressure at the opposed chamber of the actuator). In this regard, for example, the determination at block 910 may be based on whether an outlet pressure of the actuator (e.g., a maximum possible, or actual pressure) is greater than a required pressure to charge the energy storage device 650 (e.g., a required inlet pressure of an accumulator).

[0115] As noted above, whether an outflow from an actuator can charge an energy recovery device may depend on whether the outflow can reach sufficient pressure for a given pump pressure (e.g., as set by a highest-load actuator through known load-sense systems). In this regard, a maximum possible pressure of the outflow can correspond to a maximum pressure level, for the outflow of the relevant actuator, at which an inflow pressure for the actuator is maintained at a target offset from a pressure of a supply pump of the actuator (e.g., as defined by a target pressure drop of the valve system 522). In other words, for example, the maximumAttorney Docket No.: B2023-0036-W01possible pressure of the outflow may correspond to operation of the actuator 530 at a commanded operational (e.g., extension) speed, with a maximum inlet pressure for a given operating supply pressure from the supply system 510 and with a target pressure drop across the valve system 522. In some cases, in particular, the maximum possible pressure can thus correspond to a maximum outflow pressure level that does not cause a deviation from demanded flow to (and corresponding speed of) the corresponding actuator.

[0116] Upon determining that the outflow can be diverted, one or more recovery system valves (e.g., the relief valve 644) can be controlled to open a path to the energy' storage device 650, at block 912. If the outflow cannot be diverted to the energy storage device 650, the one or more recovery system valves (e.g., the proportional valve 642) can be controlled to open a flow path to tank 660, at block 914. Therefore, the method 900 can selectively direct an outflow from hydraulic actuators to tank 660 or the energy storage device 650 based on the condition of the energy storage device 650 or the load condition of the hydraulic actuators.

[0117] FIG. 10 illustrates an example hydraulic operation method 1000 for using the hydraulic system 500, and in particular the hydraulic system 600 of FIGS. 6A and 6B, although other types of hydraulic systems can be used. The method 1000 is a particular example of the method 900 of FIG. 9 and generally refers to FIGS. 6A and 6B for brevity’. To that end, discussion of above generally applies to the method 1000, except that control of one or more recovery system valves are specified in greater detail.

[0118] In some implementations, the method 1000 may include determining whether an active actuator is a highest load actuator (e.g., based on pressure signals from multiple active actuators). For a highest load actuator, the method 1000 may further determine whether the actuator is in an overrunning or resistive mode (e.g., based also on corresponding pressure signals). For operation in resistive mode, the outflow of the actuator can be routed to tank with a fully open control valve (i.e., with maximum orifice, or minimum flow restriction), and thus set the pump pressure level corresponding to the operation of the highest-load actuator for load sense supply systems.

[0119] For operation in overrunning mode, further control can be based on a determination of whether to divert the outflow to an accumulator (or other energy storage device). For example, when an actual outflow pressure of the actuator or a maximum outflow pressure is less than an accumulator pressure, flow can be routed to tank across a restricted orifice thatAttorney Docket No.: B2023-0036-W01provides back pressure corresponding to atarget supply pressure (e.g., 5-15 bar). In some cases, the target supply pressure can be set to a pre-determined value (e.g., 10 bar) that reduces or eliminates cavitation in a chamber of the actuator or throttling losses at the valves, based on characteristics of the valves. In contrast, when an outflow pressure of the actuator is (or may be) greater than an accumulator pressure, flow can be routed to an accumulator. For example, a relief command can be provided so that a pressure drop across the relief valve 644 provides an actuator outflow pressure that corresponds to atarget supply (e.g., load sense) pressure and atarget inlet pressure for the energy storage device 650.

[0120] Thus, for example, when a hydraulic actuator with the highest load is in a resistive mode, an orifice of the proportional valve 642 can be fully open to direct an outflow of the hydraulic actuator to tank 660. When the hydraulic actuator is in an overrunning mode and the outflow is not permitted to be diverted to the energy storage device 650 (e.g., accumulator), an area of the orifice of the proportional valve 642 can be controlled based on a predetermined load sense pressure of the supply system 610 (e.g., 10 bar). When the hydraulic actuator is in an overrunning mode or does not correspond to the highest load and the outflow is permitted to be diverted to the energy storage device 650, the relief valve 644 can be controlled (again) such that the pressure value of the supply system 610 matches a load sense pressure of the supply system 610.

[0121] FIG. 11 illustrates an example hydraulic operation method 1100 for using the hydraulic system 500 an in particular the hydraulic system 700 of FIGS. 7A and 7B, although other types of hydraulic systems can be used. The method 1100 is a particular example of the method 900 of FIG. 9 and generally refers to FIGS. 7A and 7B for brevity. To that end, discussion of above generally applies to the method 1100, except that control of one or more recovery system valves are specified in greater detail.

[0122] Generally, the method 1100 is similar to the method 1000 as detailed above, and discussion of particular operations illustrated in FIG. 10 thus also applies to similarly illustrated operations of FIG. 11. Thus, for example, when a hydraulic actuator is in a resistive mode, an orifice of the proportional valve 742 can be fully open, and the selector valve 744 can be controlled to direct an outflow of the hydraulic actuator to tank 760. Further, when the hydraulic actuator is in an overrunning mode and the outflow is not to be diverted to the energy storage device 750 (e.g., accumulator), the valves 742, 744 can be controlled to similarly route flow but with an orifice restriction based on a predetermined pressure for the supply systemAttorney Docket No.: B2023-0036-W01710 (e.g., 10 bar). In contrast, for example, when the hydraulic actuator is in an overrunning mode or does not correspond to the highest load and the outflow is to be diverted to the energy storage device 750, the valves 742, 744 can be controlled to route flow to the energy storage device 750, with an orifice size controlled such that the pressure of the supply system 710 matches a load sense pressure of the supply system 710.

[0123] FIG. 12 illustrates an example hydraulic operation method 1200 for using the hydraulic system 500, and in particular the hydraulic system 800 of FIGS. 8A and 8B, although other types of hydraulic systems can be used. The method 1200 is a particular example of the method 900 of FIG. 9 and generally refers to FIGS. 8A and 8B for brevity. To that end, discussion of above generally applies to the method 1200, except that control of one or more recovery system valves are specified in greater detail.

[0124] Generally, the method 1200 is similar to the method 1100 as detailed above, and discussion of particular operations illustrated in FIG. 11 thus also applies to similarly illustrated operations of FIG. 12. Thus, for example, when a hydraulic actuator with the highest load is in a resistive mode, an orifice of the proportional valve 842 can be fully open to direct an outflow of the hydraulic actuator to tank 860. When the hydraulic actuator is in an overrunning mode and the outflow is not to be diverted to the energy storage device 850 (e.g., accumulator), a restricted flow to tank 860 can be provided, with an area of the orifice of the proportional valve 842 controlled based on a predetermined pressure of the supply system 810 (e.g., 5 bar). In contrast, when the hydraulic actuator is in an overrunning mode or does not correspond to the highest load and the outflow is to be diverted to the energy storage device 850, the proportional valve 842 can route flow to the energy storage device 850. with the area of the orifice of the proportional valve 842 controlled such that the pressure of the supply system 810 matches a load sense pressure of the supply system 810.

[0125] As noted above, recovered energy that is stored by an energy recovery system can then be selectively provided to a supply (or other) hydraulic system. In this regard, for example, FIG. 13 illustrates an example hydraulic operation method 1300 using a hydraulic system such as the hydraulic system 500, the hydraulic system 600, the hydraulic system 700, or the hydraulic system 800, although other types of hydraulic systems can be used. The method 1300 generally refers to FIGS. 6A and 6B for brevity, but other hydraulic systems can be implemented to cany7out the method 1300. Although the flowchart illustrates blocksAttorney Docket No.: B2023-0036-W01sequentially and in a particular order, in some examples, at least one or more blocks are executed at least partially in parallel, in another order, or bypassed.

[0126] At block 1302, the method 1300 can include determining whether stored energy is available from the energy storage device 650. For example, the energy storage device 650 can include a pressure sensor, a level sensor, or other sensor that indicates an amount of the stored energy in the energy storage device 650. In some examples, it may be desirable to provide the stored energy at a high and sustained level to reduce a torque required to operate a supply pump during high-demand operations. Thus, in some cases, the stored energy may not be available for use until the energy storage device 650 is fully charged. In some cases, however, the energy storage device 650 may not need to be fully charged (e.g., may be available to provide boost energy once charged to a particular threshold). Generally, the availability of the stored energy may depend on a size of the energy storage device 650, a frequency of movement by hydraulic actuators, or various other factors.

[0127] In some examples, an operating quadrant of a pump system of the supply system 610 can be determined at block 1304. For example, the hydraulic system 600 can receive data for an instantaneous power consumption of a supply pump of the supply system 610. The instantaneous power consumption can be compared to an available power from the energy storage device 650 to determine whether assistance from the energy storage device 650 is needed. For example, if the energy storage device 650 is charged at 100 bar and a pump supply pressure is only 80 bar, providing power from the energy storage device 650 would effectively motor the supply pump, with corresponding inefficiencies overall. Thus, for example, by evaluating required power relative to available power at block 1304. the method 1300 can provide the stored energy to an inlet of the supply pump only at a pressure value that is appropriately equal to or lower than the required pressure of the supply pump.

[0128] In some examples, at block 1306. it can be determined if an inflow of hydraulic fluid is being routed to the energy storage device 650 (e g., from the relief valve 644). Differently put, the hydraulic system 600 can receive data to determine if there is a present flow into the energy storage device 650 from one or more hydraulic actuators. In some cases, for example, it may be advantageous to keep the control valve 652 closed when there is a flow into the energy storage device 650. For example, by keeping the control valve 652 closed to block a flow path to tank 660, a pressure of a fluid flow within the energy storage device 650 can increase more quickly, and corresponding throttling losses for the inflow to the device 650Attorney Docket No.: B2023-0036-W01can be reduced. Further, for some operations, it may be desirable to draw power from the energy storage device 650 only when fully charged (e.g., to provide maximum-duration boost flow). However, although the energy storage device 650 can generally be charged and discharged at different times according to operations at block 1306, the energy storage device 650 can be charged and discharged simultaneously in different cases. For example, for some operations, it may be useful to draw power from for energy storage devices of smaller overall capacity, even during simultaneous charging of the device(s).

[0129] At block 1308, the control valve 652 can be controlled to direct the flow from the energy storage device 650 to an inlet of the supply system 610 or an inlet of a supply pump. For example, the control valve 652 can be selectively opened based on a determination of whether stored energy is available (e.g., at block 1302), a state of the corresponding supply system (e.g., at block 1304), or a charging state of the energy storage device 650 (e.g., at block 1308). Thus, in some cases, the supply system 610 can be boosted by the flow of pressurized hydraulic fluid from the energy storage device 650, to more efficiently provide pressurized fluid to hydraulic actuators.

[0130] FIG. 14 illustrates an example method 1400 which is a particular example of the method 1300 of FIG. 13. To that end, discussion above for the blocks of the method 1300 applies to discussion of the method 1400, and the method 1400 generally refers to FIGS. 6A and 6B for brevity. In particular, the method 1400 further specifies operations of an inlet valve (e.g., the control valve 652) based on pressure or flow conditions of one or more devices of the hydraulic system 600. For example, upon the method 1400 determining the energy storage device 650 (e.g., an accumulator) is presently charging (e.g., recovering energy from an outflow of hydraulic actuators), the control valve 652 can close or remain closed. Similarly, in some cases, the control valve 652 can open or remain opened upon determining that the accumulator is not (fully) charged, that a pressure of a supply pump is less than a pressure of the accumulator, that a flowrate of the supply pump is zero, or that the accumulator is charging or recovering energy from the outflow of hydraulic actuators.

[0131] FIG. 15 illustrates an example hydraulic system 1500, which is aparticular example of the hydraulic system 500 of FIG. 5. the hydraulic system 600 of FIGS. 6A and 6B, the hydraulic system 700 of FIGS. 7A and 7B, and the hydraulic system 800 of FIGS. 8A and 8B. To that end, features of the hydraulic system 1500 described below include reference numbers that are generally similar to those used in FIGS. 5-8B, and discussion of above applies to similarAttorney Docket No.: B2023-0036-W01numbers below unless otherwise noted or required. For example, the hydraulic system 1500 includes a supply system 1510 and an energy recovery system 1540, just as the hydraulic system 500 includes the supply system 510 and the energy recover}' system 540.

[0132] In some aspects, the hydraulic system 600 and the hydraulic system 1500 differ. For example, a valve system 1520 includes a first valve subsystem 1522 and a second valve subsystem 1524. The first valve subsystem 1522 and the second valve subsystem 1524 can include independent metering valves that independently control an inflow of hydraulic fluid into and an outflow of the hydraulic fluid out of the first actuator 1530 and the second actuator 1532, respectively. In particular, mechanical connections between a meter-in valve and a meter-out valve can be separated, such that a relationship between opening areas of the meterin valve and the meter-out valve are independent. Accordingly, the first valve subsystem 1522 and the second valve subsystem 1524 can achieve flow and pressure of hydraulic fluid into and from the first actuator 1530 and the second actuator 1532, respectively, with greater flexibility. In the illustrated example, the first valve subsystem 1522 and the second valve subsystem 1524 can operate with a constant pressure at a pump of the supply system 1510.

[0133] The energy recovery system 1540 can include a plurality of recover}' system valves for each of the first valve subsystem 1522 and the second valve subsystem 1524. Thus, outflows of hydraulic fluid from the first actuator 1530 and the second actuator 1532 can be separately recovered by the energy recovery system 1540, for example, as illustrated in FIG. 16. In some cases, different amounts of recoverable energy can be available based on operating modes or demands of the first actuator 1530 and the second actuator 1532 as illustrated in FIG. 16.

[0134] FIGS. 17-19 illustrate example hydraulic systems, which are particular examples of the hydraulic system 500 of FIG. 5, the hydraulic system 600 of FIGS. 6A and 6B, the hydraulic system 700 of FIGS. 7A and 7B, the hydraulic system 800 of FIGS. 8A and 8B, or the hydraulic system 1500 of FIG. 15. To that end, features of a hydraulic system 1700 of FIG. 17. a hydraulic system 1800 of FIG. 18, and a hydraulic system 1900 of FIG. 19 described below include reference numbers that are generally similar to those used in FIGS. 5-8B and FIG. 15, and discussion of above applies to similar numbers below unless otherwise noted or required. For example, the hydraulic system 1700 includes a supply system 1710 and an energy recovery system 1740, the hydraulic system 1800 includes a supply system 1810 and an energy recovery system 1840, the hydraulic system 1900 includes a supply system 1910 and an energy recoveryAttorney Docket No.: B2023-0036-W01system 1940, just as the hydraulic system 1500 includes the supply system 1510 and the energy recovery system 1540.

[0135] However, the hydraulic system 1700, the hydraulic system 1800, and the hydraulic system 1900 differ from the hydraulic system 1500 in some aspects. For example, a valve system 1720 of the hydraulic system 1700, a valve system 1820 of the hydraulic system 1800, and a valve system 1920 of the hydraulic system 1900 can include independent metering control that is pressure compensated. For example, a first valve subsystem 1722 and a second valve subsystem 1724 can include meter-in valves that are post-compensated. Likewise, a first valve subsystem 1822 and a second valve subsystem 1824 can include meter-in valves that are post-compensated, with relief valves that are controlled differently than relief valves of the valve system 1720. Further, a first valve subsystem 1922 and a second valve subsystem 1924 can include meter-in valves that are pre-compensated. Accordingly, energy can be recovered from hydraulic actuators in communication with valve systems that are post-compensated or pre-compensated. As illustrated in FIG. 20, throttling losses in meter-out valves can be reduced by incorporating pressure compensated valve systems and a load-sensing pump that is hydraulically or electronically controlled.

[0136] FIGS. 21 A and 21B illustrate example configurations of an inlet of a supply system for a hydraulic system, which can be incorporated into any one of the hydraulic systems depicted in FIGS. 5-8B, 15, or 17-19. To that end, discussion of above generally applies to discussion relative to various substantially identical features, such as an energy storage device 2150 of an energy recovery system 2140 and a control valve 2152.

[0137] However, hydraulic systems of FIGS. 21 A and 21B differ, including with regard to supply inlet configurations. In particular, as shown in FIG. 21 A, a supply motor 2112 can be provided on a shaft with a supply pump 2114, which receives hydraulic fluid from tank 2160 for operation. In the present embodiment, the supply motor 2112 can be a fixed speed engine, and the supply pump 2114 can be a single variable displacement pump.

[0138] Of note, a hydraulic motor 2170 can also be mechanically connected with (e.g., on the same rotating shaft as) the supply motor 2112 and the supply pump 2114. Further, the hydraulic motor 2170 can receive pressurized hydraulic fluid from the energy storage device 2150, when available, to power rotation of the motor 2170. For example, the control valve 2152 can open a path to direct a flow of hydraulic fluid to the hydraulic motor 2170, and then to tankAttorney Docket No.: B2023-0036-W012160 via an orifice of appropriate sizing according to various approaches detailed above. Accordingly, by drawing down energy stored in the energy storage device 2150, the hydraulic motor 2170 can supply assistive rotational power to the supply pump 2114, e.g., to supply fluids to downstream actuators or other hydraulic systems.

[0139] Turning to FIG. 2 IB, in an alternate configuration, a supply motor 2116 of the supply system 2110 can be a variable speed electric motor, and a supply pump 2118 can be a fixed displacement pump (e.g., arranged as a single workgroup pump). Further, a supply line from the energy storage device 2150 can be provided from the control valve 2152 to an inlet of the supply pump 2118. Thus, in the example illustrated, the control valve 2152 can selectively open to provide pressurized hydraulic fluid to the supply pump 2118 (e.g., to replace flow from tank 2160).

[0140] Although the illustrated configurations may be particularly beneficial, for efficiency or ease of control, other configurations are possible. For example, the hydraulic motor 2170 of FIG. 21 A or other similar devices can be arranged to provide boost power relative to differently configured pumps, or to assist other types of main drivers. Similarly, the flow arrangement of FIG. 21 B or other similar flow arrangements can be arranged to provide boost flow to differently configured pumps, or pumps driven by different types of main drivers.

[0141] Further in this regard, FIGS. 22A-22C illustrate additional example configurations of a supply system 2210 with a tandem pump configuration. In particular, a plurality of pumps can be provided, powered by a motor (or other driver), to provide a flow of pressurized fluid to one or more hydraulic actuators (e.g., via a common valve system). Further, an unloading valve system can be provided to selectively route flow from the plurality of pumps to the actuator(s) or to tank, based on a desired pressure level of a flow of hydraulic fluid to be supplied to hydraulic actuator(s). Additionally, the pump(s) can also, in some cases, be arranged to be boosted by flow or power from an energy recovery system.

[0142] With specific reference to FIG. 22A, a supply motor 2212 can be provided to power a first pump 2280, a second pump 2282, and a third pump 2284 that are arranged in parallel and coupled to the same shaft (e.g., with each pump 2280, 2282, 2284 operating simultaneously, in tandem). In some cases, the supply motor 2212 can be a variable speed electric motor, although different types of drivers are possible, including an internal combustion or other fixed speed driver 2214, as shown in the alternate configuration of FIG.Attorney Docket No.: B2023-0036-W0122B. In some examples, the pumps 2280, 2282, 2284 may be relatively simple pumps (e.g., fixed displacement gear pump) to provide a more inexpensive system, with improved control over flow regimes for the supply system 2210 as further detail below.

[0143] As regulated by an unloading valve system (e.g., as further detailed below), the first pump 2280, the second pump 2282, and the third pump 2284 can be selectively operated to provide flow for workgroup operations in different respective pressure and flow regimes (e.g., as illustrated in FIG. 23). Thus, the first pump 2280, the second pump 2282, and the third pump 2284 can be available to provide a flow of hydraulic fluid to hydraulic actuators more efficiently than a single pump sized to cover the same ranges of pressure and flow (e.g., as indicated by an offset dot on the pressure-flow diagram of FIG. 23). In some cases, a size of the supply motor 2212 can correspondingly also be downsized.

[0144] Generally, an unloading valve system 2290 can include a plurality of pathways for the first pump 2280. the second pump 2282, and the third pump 2284, which can selectively divert an outflow' from the first pump 2280 or the second pump 2282 based on present operating conditions (or other factors). For example, as illustrated, respective unloading valves 2292, 2294 can be provided betw een an outlet of the first pump 2280 and tank 2260, and betw een an outlet of the second pump 2282 and tank 2260. e.g., with respective relief settings pl*. p2*. Generally, the set pressure of the relief valve for the first pump 2280 can be different than the set pressure of the relief valve for the second pump 2280. For example, pl* for the first valve 2292 can be less than p2* for the second valve 2294.

[0145] Thus, according to the relief settings pl*, p2*, the corresponding unloading valve 2292, 2294 can open or close depending on the present supply pressure of the supply system 2210 (e.g., as controlled by load-sense or other systems). Correspondingly, as also represented in the pressure-flow diagram of FIG. 23, at particular supply pressures the unloading valve system 2290 can cause an outflow of one or more of the pumps 2280, 2282 to bypass the hydraulic actuators (or other downstream loads) and return to tank 2260.

[0146] In particular, in the illustrated example, with pl* < p2*, when the supply pressure is less than pl*, the three pumps 2280, 2282, 2284 may collectively provide a relatively high flow rate. When the supply pressure exceeds pl* but remains less than p2*, flow from the pump 2280 can be routed to tank 2260, and the two pumps 2282, 2284 may collectively provide a somewhat lower flow' rate, at the higher pressure. Finally, when the supply pressure exceedsAttorney Docket No.: B2023-0036-W01p2*, flow from the pump 2282 can also be routed to tank 2260, and thus only the pump 2284 (of the three) may provide a relatively high pressure and lower flow rate flow for downstream operations.

[0147] As noted above, the supply system 2210 can also receive boosting power or flow from the energy recover)’ system 2240. For example, as illustrated in FIGS. 22A through 22C, an inlet of the third pump 2284 can be in communication with the energy storage device 2250, via the control valve 2252. Thus, additional energy can be provided to operate the third pump 2284 by providing recovered pressurized flow from the energy’ storage device 2250 to an inlet of the third pump 2284 (e.g., to provide a boosting, pressurized inlet flow during high pressure operation of the relevant actuator, with sole supply from the pump 2284).

[0148] Turning to FIG. 22C, in some examples, unloading valves 2296, 2298 of the unloading valve system 2292 can be electronically operated (e.g., by solenoids) to allow for electronic control over which of the pumps 2280, 2282, 2284 supply flow to power a particular operation. Thus, in some cases, the unloading valves can be controlled at least partly independently of a pressure condition of hydraulic fluid (e.g., controlled to open at a supply pressure value lower than a set pressure of the corresponding unloading valve). In some cases, such selective operation of the unloading valve system 2290 can help to conserve power. For example, at low flow and low pressure operations, as indicated by pressure signals, operator inputs, or other factors, the valves 2296, 2298 can be controlled to open at below the corresponding set pressure, so that flow from one or both of the pumps 2280, 2282 is routed (with minimal power loss) to tank 2260.

[0149] The valve arrangements illustrated for the unloading valve system 2290 can be useful across a variety’ of power machine implementations, including to provide improvements in efficiency as detailed above. In some cases, however, a different valve control mechanism (e.g.. an intelligent valve system) can be provided to regulate flow of the first pump 2280. the second pump 2282, or the third pump 2284 relative to a commanded operation. For example, the unloading valve system 2290 as shown, or other components, can be replaced in some cases with a unified valve system (e.g., with electronically controlled spool(s) to selectively route flow from one or more of the relevant pumps to tank based on present operating conditions).

[0150] FIG. 24 illustrates an example hydraulic system 2400 and an energy recovery system 2440, which are particular examples of the hydraulic system 500 and the energyAttorney Docket No.: B2023-0036-W01recovery system 540 of FIG. 5, the hydraulic system 600 and the energy recovery system 640 of FIGS. 6A and 6B, the hydraulic system 700 and the energy recovery system 740 of FIGS.7A and 7B, and the hydraulic system 800 and the energy recovery system 840 of FIGS. 8A and 8B. To that end, features of the hydraulic system 2400 and the energy recovery system 2440 described below include reference numbers that are generally similar to those used in FIGS 5-8B. and discussion of above applies to similar numbers below unless otherwise noted or required. For example, the hydraulic system 2400 includes a supply system 2410, a valve system 2420, and an actuator 2430 just as the hydraulic system 600 includes the supply system 610, the valve system 620, and the actuator 630. Further, the energy recovery system 2440 includes a proportional valve 2442 and a relief valve 2444, just as energy recovery system 640 includes the proportional valve 642 and the relief valve 644.

[0151] In some aspects, the energy recovery’ system 2440 and the energy' recovery' system 640 differ. In particular, a hydraulic transformer 2462 is provided between the relief valve 2444 and an energy storage device 2450. The hydraulic transformer 2462 can receive a flow of hydraulic fluid from the hydraulic actuators via the relief valve 2444 and be thus powered to provide pressurized flow to boost the supply system 2410. For example, when a potential recoverable energy from a hydraulic actuator is 90 bar, the hydraulic transformer 2462 can provide flow to the energy’ storage device or to the supply or valve systems 2410, 2420 at a pressure greater than 90 bar (e.g., 250 bar).

[0152] In the illustrated example, a proportional reducing valve 2456 can selectively supply a boost flow of pressurized hydraulic fluid to the supply system 2410 with a regulated pressure (e.g., to match a supply pressure from the pump 2414. up to the elevated pressure of flow from the energy storage device 2450 or the transformer 2462). In some cases, the flow from the energy' recovery system 2440 can be combined with (or replace) a flow of pressurized fluids from a supply pump 2414 of the supply system 2410. Therefore, the hydraulic transformer 2462 can assist in achieving a desired flow rate of hydraulic fluid for elevated pressure operations of the hydraulic system 2400. In some cases, a compensated valve (e.g., a control valve in series with a pressure reducing valve) can be provided to selectively supply a boost flow to the supply system 2410.

[0153] Thus, examples of the disclosed technology can provide improved energy recovery from hydraulic systems, particularly during operation of hydraulic actuators as supplied by a dedicated hydraulic supply system. Further, in some examples, the disclosed technology7canAttorney Docket No.: B2023-0036-W01provide improved supply for various hydraulic operations (e.g., via particular configurations of supply systems or via particular arrangements to provide boost power or flow). Although the present invention has been described by referring preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the discussion.

[0154] Also as used herein, unless otherwise specified or limited, “or” indicates a nonexclusive list of components or operations that can be present in any variety of combinations, rather than an exclusive list of components that can be present only as alternatives to each other. For example, a list of “A, B, or C” indicates options of: A; B; C; A and B; A and C; B and C; and A, B. and C. Correspondingly, the term “or” as used herein is intended to indicate exclusive alternatives only when preceded by terms of exclusivity, such as “only one of,” or “a single one of.” For example, a list of “only one of A, B, or C” indicates options of: A, but not B and C; B, but not A and C; and C, but not A and B. In contrast, a list preceded by “one or more” (and variations thereon) and including “or” to separate listed elements indicates options of one or more of any or all of the listed elements. For example, the phrases “one or more of A, B, or C” and “at least one of A, B, or C” indicate options of: one or more A; one or more B; one or more C; one or more A and one or more B; one or more B and one or more C; one or more A and one or more C; and one or more A, one or more B, and one or more C. Similarly, a list preceded by “a plurality of’ (and variations thereon) and including “or” to separate listed elements indicates options of one or more of each of multiple of the listed elements. For example, the phrases “a plurality of A, B, or C” and “two or more of A, B, or C” indicate options of: one or more A and one or more B; one or more B and one or more C; one or more A and one or more C; and one or more A, one or more B, and one or more C.

[0155] It is to be understood that the phraseology' and terminology' used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising.” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Further, unless otherwise noted, features or functionality of any particular example presented herein can be substituted into or otherwise combined with other examples, including to supplement or replace various features or functionality of the other examples.

[0156] Likewise, unless otherwise specified or limited, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both directAttorney Docket No.: B2023-0036-W01and indirect mountings, connections, supports, and couplings. Further, unless otherwise specified or limited, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

[0157] In some embodiments, aspects of the invention, including computerized implementations of methods according to the invention, can be implemented as a system, method, apparatus, or article of manufacture using standard programming or engineering techniques to produce software, firmware, hardw are, or any combination thereof to control a processor device (e.g., a serial or parallel general purpose or specialized processor chip, a single- or multi-core chip, a microprocessor, a field programmable gate array, any variety of combinations of a control unit, arithmetic logic unit, and processor register, and so on), a computer (e g., a processor device operatively coupled to a memory), or another electronically or operated controller to implement aspects detailed herein. Accordingly, for example, embodiments of the invention can be implemented as a set of instructions, tangibly embodied on a non-transitory computer-readable media, such that a processor device can implement the instructions based upon reading the instructions from the computer-readable media. Some embodiments of the invention can include or utilize a control device (or controller) such as an automation device, a special purpose or general purpose computer including various computer hardware, software, firmware, and so on, consistent with the discussion below. As specific examples, a control device can include a processor, a microcontroller, a field-programmable gate array, a programmable logic controller, logic gates etc., and other typical components that are known in the art for implementation of appropriate functionality (e.g., memory, communication systems, power sources, user interfaces and other inputs, etc.). In some embodiments, a control device can include a centralized hub controller that receives, processes and (re)transmits control signals and other data to and from other distributed control devices (e.g., an engine controller, an implement controller, a drive controller, etc.), including as part of a hub-and-spoke architecture or otherwise.

[0158] The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier (e.g., non-transitory signals), or media (e.g., non-transitory media). For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, and so on), optical disks (e.g., compact disk (CD), digital versatile disk (DVD), and so on), smart cards, and flash memory devices (e.g., card, stick, and so on). Additionally, it shouldAttorney Docket No.: B2023-0036-W01be appreciated that a carrier wave can be employed to carry computer-readable electronic data such as those used in transmitting and receiving electronic mail or in accessing a network such as the Internet or a local area network (LAN). Those skilled in the art will recognize that many modifications may be made to these configurations without departing from the scope or spirit of the claimed subject matter.

[0159] Certain operations of methods according to the disclosed technology, or of systems executing those methods, may be represented schematically in the FIGS, or otherwise discussed herein. Unless otherwise specified or limited, representation in the FIGS, of particular operations in particular spatial order may not necessarily require those operations to be executed in a particular sequence corresponding to the particular spatial order. Correspondingly, certain operations represented in the FIGS., or otherwise disclosed herein, can be executed in different orders than are expressly illustrated or described, as appropriate for particular examples of the disclosed technology. Further, in some examples, certain operations can be executed in parallel, including by dedicated parallel processing devices, or separate computing devices configured to interoperate as part of a large system.

[0160] As used herein in the context of computer implementation, unless otherwise specified or limited, the terms “component." “system,” “module.” “block,” “device.” and the like are intended to encompass part or all of computer-related systems that include hardware, software, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a processor device, a process being executed (or executable) by a processor device, an object, an executable, a thread of execution, a computer program, or a computer. By way of illustration, both an application running on a computer and the computer can be a component. One or more components (or system, module, and so on) may reside within a process or thread of execution, may be localized on one computer, may be distributed between two or more computers or other processor devices, or may be included within another component (or system, module, and so on).

[0161] Also as used herein, unless otherwise specified or limited, “configured to” indicates that a component, system, or module is particularly adapted for the associated functionality'. Thus, for example, an XX configured to YY is specifically adapted to YY, as opposed to merely being generally capable of doing so.Attorney Docket No.: B2023-0036-W01

[0162] In some implementations, devices or systems disclosed herein can be utilized, manufactured, installed, etc. using methods embodying aspects of the disclosed technology. Correspondingly, unless otherwise indicated, any description herein of particular features, capabilities, or intended purposes of a device or system should be considered to disclose, as examples of the disclosed technology a method of using such devices for the intended purposes, a method of otherwise implementing such capabilities, a method of manufacturing relevant components of such a device or system (or the device or system as a whole), and a method of installing disclosed (or otherwise known) components to support such purposes or capabilities. Similarly, unless otherwise indicated, discussion herein of any method of manufacturing or using for a particular device or system, including installing the device or system, should be understood to disclose, as examples of the disclosed technology, the utilized features and implemented capabilities of such device or system.

[0163] Some methods of the disclosed technology may be presented above or below with operations listed in a particular order. Unless otherwise required or specified, the operations of such methods can be implemented in different orders, in parallel, or as selected sub-sets of one or more individual operations (e.g., with a particular listed operation being implemented alone, rather than in combination with others).

[0164] Also as used herein in the context of power machines, unless otherwise defined or limited, ‘"tractive” or “drive” are used to designate actuators and other work elements of a pow er machine that can be powered by a power source to cause movement of the power machine over terrain (e.g., wheeled or tracked ground-engaging elements, motors configured to power ground-engaging elements, and related assemblies). In contrast, “workgroup” is used to designate actuators or other work elements of a power machine associated with powered operation of work elements that are not configured to provide pow ered travel over terrain (e.g., lift arm structures, attached implements, motors or other actuators to power movement of lift arm structures or attached implements, auxiliary power take-off interfaces, and related assemblies). Thus, tractive (or drive) actuators are arranged to power travel of a pow er machine whereas w orkgroup actuators are arranged to power non-travel work operations of the powder machine. Correspondingly, discussion of workgroup functions refers to one or more functions provided by movement of one or more workgroup elements of a power machine, whereas discussion of tractive (or drive) functions refer to one or more functions provided for movement of the power machine itself over terrain.Attorney Docket No.: B2023-0036-W01

[0165] Also as used herein in the context of hydraulic flow, unless otherwise specified or limited, “between” indicates a component or path that is along a flow from a first reference component to a second reference component. For example, a heat exchanger located “between” an upstream pump and a downstream tank may be located so that flow from the pump passes through the heat exchanger to reach the tank. Similarly, as used herein in the context of hydraulic flow, unless otherwise specified or limited, “communication” indicates the ability’ of hydraulic fluid to flow within a system between particular components. Unless otherwise specified, hydraulic components are not considered to be in communication with each other simply by way of sharing a common tank.

Claims

Attorney Docket No.: B2023-0036-W01CLAIMS1. A hydraulic system for a power machine, the hydraulic system comprising: a supply system configured to provide pressurized fluid to a hydraulic actuator; and an energy recovery system that includes:an energy storage device;a first valve having a first position that permits an outlet flow from the hydraulic actuator to flow across the first valve and a second position that blocks the outlet flow7from the hydraulic actuator from flowing across the first valve; anda second valve arranged to control flow of the outlet flow from the hydraulic actuator to the energy storage device.

2. The hydraulic system of claim 1, wherein the first valve is in parallel to the second valve relative to the outlet flow from the hydraulic actuator; andwherein the first valve, in the first position, permits the outlet flow from the hydraulic actuator to flow across the first valve to tank.

3. The hydraulic system of claim 2, wherein the first valve is a 2-way proportional valve.

4. The hydraulic system of either of claims 2 or 3, wherein the second valve is an electro-proportional relief valve.

5. The hydraulic system of claim 1. wherein the first valve is in series with the second valve relative to the outlet flow from the hydraulic actuator; andwherein the first valve:in the first position, permits the outlet flow from the hydraulic actuator to flow to the second valve; andin the second position, blocks the outlet flow from the hydraulic actuator from flowing to the second valve.

6. The hydraulic system of claim 5, wherein the first valve is a 2-way proportional valve.Attorney Docket No.: B2023-0036-W017. The hydraulic system of either of claims 5 or 6, wherein the second valve is a selector valve that:in a first position, routes flow received from the first valve to the energy storage device ; andin a second position, diverts the flow received from the first valve to tank.

8. The hydraulic system of any of the preceding claims, further comprising: a first metering valve and a second metering valve that are independently controllable to permit or block flow of the outlet flow from the hydraulic actuator to the energy recovery system.

9. The hydraulic system of any of the preceding claims, further comprising: a control valve arranged between the energy storage device and the supply system, the control valve being electronically controllable to selectively permit or block flow from the energy storage device to the supply system.

10. The hydraulic system of any of the preceding claims, wherein flow from the energy storage device operates a hydraulic motor to provide rotational power to the supply system.

11. The hydraulic system of any of claims 1 through 9, wherein flow from the energy storage device is provided to an inlet of a pump of the supply system that provides the pressurized fluid to the hydraulic actuator.

12. The hydraulic system of claim 11, wherein the pump of the supply system is a fixed displacement pump.

13. The hydraulic system of either of claims 11 or 12, wherein supply system includes:a plurality of additional pumps that provide the pressurized fluid to the hydraulic actuator; anda valve system to selectively divert outflow from any of the plurality of additional pumps to tank, bypassing the hydraulic actuator.Attorney Docket No.: B2023-0036-W0114. The hydraulic system of claim 13, wherein the valve system includes:a first pressure relief valve with a first set pressure arranged between a first pump of the plurality of additional pumps and tank; anda second pressure relief valve with a second set pressure arranged between a second pump of the plurality of additional pumps and tank, the second set pressure being greater than the first set pressure.

15. The hydraulic system of claim 14, wherein the first and second pressure relief valves are solenoid operated pressure relief valves.

16. The hydraulic system of any of the preceding claims, wherein the supply system is configured to provide pressurized fluid to the hydraulic actuator via a precompensated control valve system.

17. The hydraulic system of any of the preceding claims, wherein the energy storage system is an accumulator arranged to be charged by the outlet flow from the hydraulic actuator.

18. A method of recovering energy from one or more hydraulic actuators of a power machine, the method comprising:determining whether an actuator is a highest-load actuator;upon determining that the actuator is the highest-load actuator, determining whether a working mode of the actuator of the one or more hydraulic actuators is a resistive load mode or an overrunning load mode;upon determining that the working mode is the resistive load mode, controlling one or more valves of an energy' recovery' system to divert an outflow from the actuator to tank; upon determining that the working mode is the overrunning load mode:determining a maximum pressure of the outflow from the actuator; and based on determining the maximum pressure, selectively:controlling the one or more valves of the energy recovery system to route the outflow from the actuator to an energy storage device of the energy recovery' system; orcontrolling the one or more valves of the energy recovery system to divert the outflow from the actuator to tank; andAttorney Docket No.: B2023-0036-W01releasing pressurized flow from the energy storage device to boost a supply system that provides pressurized fluid to the one or more hydraulic actuators.

19. The method of claim 18, further comprising, upon determining that the actuator is not the highest-load actuator:determining a maximum pressure of the outflow from the actuator; andbased on determining the maximum pressure, selectively:controlling the one or more valves of the energy recovery system to route the outflow from the actuator to an energy' storage device of the energy' recovery system; orcontrolling the one or more valves of the energy recovery system to divert the outflow from the actuator to tank.

20. The method of claim 18, wherein releasing the pressurized flow from the energy storage device to boost the supply system includes:determining if stored energy is available from the energy storage device; and if stored energy' is available from the energy storage device , controlling an inlet valve to direct flow from the energy' storage device to the supply system.

21. The method of claim 20, wherein releasing the pressurized flow from the energy storage device to boost the supply system further includes controlling the inlet valve based on one or more of:determining an operating quadrant for a pump of the supply system; and determining if the one or more valves of the energy recovery system are routing the outflow from the actuator to the energy storage device.

22. The method of any of claims 18 through 21, wherein the pressurized flow from the energy storage device is directed to an inlet of a first pump of the supply system; andwherein the supply system further includes a plurality of additional pumps that provide the pressurized fluid to the one or more hydraulic actuators in parallel with the first pump.Attorney Docket No.: B2023-0036-W0123. The method of claim 22, further comprising:controlling one or more valves of the supply system to selectively divert outflow from one or more of the plurality of additional pumps to tank.

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