Expansion machine, prime mover system and power plant comprising an expansion machine
Patent Information
- Application Number
- PCT/EP2026/058697
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2026-03-26
- Publication Date
- 2026-10-01
Smart Images
Figure EP2026058697_01102026_PF_FP_ABST
Abstract
Description
[0001] A25302DE
[0002] - 1 -
[0003] Karlsruhe Institute of Technology, a public corporation, March 26, 2026, KIT25302PC / ST / PF / PF
[0004] Expansion machine, power machine system and power plant with an expansion machine
[0005] Technical field
[0006] The present invention relates to an expansion machine, a power machine system and a power plant with an expansion machine.
[0007] Technical background
[0008] Expansion machines come in a wide variety of types and forms. The valve openings can be actuated in fundamentally different ways. A basic distinction can be made between harmonic (sinusoidal) oscillation and disharmonic oscillation actuated by a cam.
[0009] Many expansion engines, especially steam engines in locomotives and ships, are operated with harmonic-driven control valves that move at the same speed as the working piston. These drives were mostly developed many years or even decades ago, with efficiency being secondary to engine power. As a result, the opening times of the control valves in such engines were usually chosen to be very long in order to achieve high power densities during start-up and thus set large masses, such as trains or ships, in motion. In ferry operation, when lower power outputs suffice, the valve opening time, and therefore the engine power, was reduced.
[0010] - 2 -
[0011] Despite the numerous advantages of expansion engines known from the prior art, they still exhibit potential for improvement. Historically, throttling the supplied steam was the preferred method for reducing power output, with disastrous consequences for efficiency due to the reduction in pressure and temperature. Reducing the valve opening time already offers a noticeable efficiency advantage over the original approach. However, because a reduction in valve opening time inevitably leads to a reduction in the slide valve opening cross-section, considerable potential is wasted. It is known that in expansion engines, the inflow duration must be very short to achieve high engine efficiency. The harmonic oscillation results in very smooth and durable engine operation. However, the slope of the sine function is lower at short opening durations, i.e.,Near the reversal point, the pressure is very small. This leads to very slow valve opening and therefore high throttling losses.
[0012] Piston engines, especially those operated according to the ORC principle, utilize the valve technology of modern internal combustion engine designs, namely cam-operated poppet valves. The cams must be very sharply shaped to enable high opening speeds. This results in high accelerations, which must be counteracted by high return forces from the valve springs. This increases wear and reduces service life. These concepts were also implemented in steam expansion engines for mobile applications in passenger cars. Piston valves are a known alternative to poppet valves. With proper actuation, a piston valve can open a significantly larger cross-section than a poppet valve. As described above, this has a beneficial effect on efficiency. The disadvantages of piston valves include higher maintenance requirements, as the piston rings travel over the intake port, thus increasing their wear.Furthermore, the level of technical development is lower than that of poppet valves, which have undergone intensive development in recent decades. A larger installation space is also required for gate valves compared to poppet valves.
[0013] According to the current state of the art, it is not possible to actuate harmonically moving actuators or control elements briefly and quickly. The current state of the art allows either non-harmonically but quickly moving control elements or harmonically but briefly and slowly moving control elements. A25302DE
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[0015] Object of the invention
[0016] It would therefore be desirable to provide an expansion machine and a power plant with an expansion machine that largely avoid the disadvantages of known expansion machines and power plants. In particular, the expansion machine should enable high opening speeds and low throttling losses at short opening times.
[0017] General description of the invention
[0018] This task is addressed by an expansion machine, a power machine system, and a power plant with an expansion machine, having the features of the independent claims. Advantageous further developments, which can be implemented individually or in any combination, are described in the dependent claims.
[0019] In the following, the terms "have," "exhibit," "comprise," or "include," or any grammatical variations thereof, are used in a non-exclusive manner. Accordingly, these terms can refer both to situations in which, apart from the features introduced by these terms, no other features are present, and to situations in which one or more additional features are present. For example, the expression "A has B," "A exhibits B," "A comprises B," or "A includes B" can refer both to the situation in which, apart from B, no other element is present in A (i.e., a situation in which A consists solely of B) and to the situation in which, in addition to B, one or more other elements are present in A, such as element C, elements C and D, or even further elements.
[0020] It is further noted that the terms "at least one" and "one or more," as well as grammatical variations of these terms, when used in connection with one or more elements or features and intended to express that the element or feature may be provided for once or multiple times, are generally used only once, for example, when the feature or element is first introduced. Upon subsequent mention of the feature or element, the corresponding term "at least one" or "one or more" is generally no longer used, without restricting the possibility that the feature or element may be provided for once or multiple times.
[0021] - 4 -
[0022] Furthermore, the terms "preferably," "in particular," "for example," or similar terms are used in the following text in conjunction with optional features without limiting alternative embodiments. Features introduced by these terms are optional features, and it is not intended that these features limit the scope of protection of the claims, and in particular the independent claims. As the person skilled in the art will recognize, the invention can also be implemented using other embodiments. Similarly, features introduced by "in one embodiment of the invention" or by "in an exemplary embodiment of the invention" are understood as optional features without limiting alternative embodiments or the scope of protection of the independent claims.Furthermore, these introductory expressions are intended to leave all possibilities of combining the features introduced herein with other features, whether optional or non-optional features, unaffected.
[0023] In a first aspect, the present invention relates to an expansion machine. The expansion machine has at least one cylinder that defines a working chamber. In such a working chamber, a working piston can perform mechanical work by moving back and forth.
[0024] The cylinder has an inlet port for introducing a working medium into the working chamber and an outlet port for releasing it from the working chamber. The working medium can be a gas, a gas mixture, or steam. The expansion of the gas or steam in the working chamber causes usable mechanical work to be performed. The pressurized steam or gas converts the thermal energy (also called pressure energy) it contains into kinetic energy by moving a piston within the cylinder.
[0025] The expansion engine also features a working piston that is arranged to move back and forth within the cylinder. The expansion of gas or steam in the working chamber causes usable mechanical work to be performed. The pressurized steam or gas converts the thermal energy (also known as pressure energy) it contains into kinetic energy by moving the working piston within the cylinder.
[0026] - 5 -
[0027] The expansion machine also features a control element designed for selectively opening and closing the inlet port. This control element is mounted outside the cylinder and is reciprocally movable. Thus, opening the inlet port allows the working fluid to flow into the working chamber, where it expands and moves the working piston. After expansion, the working fluid can flow out of the working chamber through the outlet port. The movements of the working piston and the control element are synchronized such that the speed of the control element is half that of the working piston. This enables high opening speeds and low throttling losses at short opening times.
[0028] The working piston can move linearly back and forth. Alternatively or additionally, the control element can also move linearly back and forth. This results in a simple and low-wear movement for the working piston and / or the control element.
[0029] Preferably, the working piston and the control element move harmonically back and forth. The harmonic or sinusoidal oscillation results in very smooth and durable machine operation. However, the slope of the sine function is very small at short opening times, i.e., near the reversal point. This leads to very slow opening of the valves in the form of the control element and the inlet port, and thus to high throttling losses. The sine function also exhibits regions with very high gradients, which, however, occur around the zero point. In order to utilize these times for valve actuation, the present invention proposes halving the travel speed, i.e., the rotational speed of the control element relative to the working piston. This enables high opening speeds and low throttling losses at short opening times. At the same time, the advantages of harmonic and minimally accelerated component excitation are maintained.
[0030] The control element can be designed as a control piston or control slide. This allows the control element to be used as a valve that opens and closes the inlet port.
[0031] The expansion machine may further include a control cylinder. The control cylinder may define a control chamber. The control piston may be arranged to move back and forth within the control chamber. The control chamber may have at least one inlet opening for the working medium to enter the control chamber and one outlet opening for the working medium to exit the control chamber. The control chamber may be configured as shown in A25302DE.
[0032] - 6 -
[0033] The working medium must undergo at least one deflection along its flow path from the inlet opening to the outlet opening.
[0034] This allows the working medium to be well sealed in the radial direction by the control piston.
[0035] The inlet and outlet openings can be arranged with an offset relative to each other in the axial direction of the control cylinder. This allows for a particularly simple way of achieving the deflection.
[0036] The control piston can comprise a first control piston section and a second control piston section. On the first control piston section, a first piston ring and a second piston ring can be arranged circumferentially around the control piston. The first and second piston rings of the first control piston section can be spaced apart axially. On the second control piston section, a first piston ring and a second piston ring can be arranged circumferentially around the control piston. The first and second piston rings of the second control piston section can be spaced apart axially. This creates a space between the piston rings that does not provide a seal and therefore does not impede the flow of a linearly moving working medium.
[0037] The control piston can have a piston recess. This allows the working medium to either exit from the outlet opening if the piston recess is aligned with the outlet opening, or to block the outlet if the piston recess is not aligned with the outlet opening.
[0038] The control piston can define an interior space. This interior space can be fluid-connected to the piston recess. Thus, the control piston can be hollow and the working medium can flow through it in an axial direction. The working medium can be deflected twice in this process.
[0039] The control element can have a first control edge and a second control edge. The first control edge and the second control edge can each be configured to release the inlet opening during a forward movement and to open the inlet opening during a reverse movement, and vice versa. By halving the rotational speed or movement-A25302DE
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[0041] The speed of the control element relative to the working piston results in two control edges, each of which opens during an upward movement and closes during a downward movement, and vice versa.
[0042] The expansion machine can further comprise at least one first and a second sliding crank mechanism. The working piston can be moved back and forth by means of the first sliding crank mechanism. The control element can also be moved back and forth by means of the first sliding crank mechanism. The first and second sliding crank mechanisms can be connected such that the rotational speed of the second sliding crank mechanism is half that of the first. With such sliding crank mechanisms, the linear motion of the working piston or control element can be converted from a rotary motion into an oscillating linear motion, or vice versa. Thus, the linear motion of the working piston can be converted into a rotary motion of, for example, a flywheel or gear, which in turn can drive a shaft and / or another component.
[0043] The gear ratio of the first and second crankshaft drives is preferably i = 1 :2. Thus, the rotational speed of the second crankshaft drive is half that of the first crankshaft drive.
[0044] The first and second crankshaft drives can be connected by means of gears, a toothed belt, or a timing chain. Therefore, the speeds of the first and second crankshaft drives can be fixed or unadjustable relative to each other.
[0045] The control element can alternatively be driven separately from the working piston. This increases flexibility in designing the control element's drive mechanism. This includes, for example, actuating the control element with an electric, hydraulic, or pneumatic actuator.
[0046] In another aspect, the present invention relates to a power machine system. The power machine system comprises at least one generator configured to generate electrical energy and at least one expansion machine according to one of the embodiments described above or below. The expansion machine is configured to drive the generator. Alternatively, the power machine system can comprise at least one compressor, in particular an air compressor, a pump, and / or a driven machine. The expansion machine is configured to drive the A25302DE
[0047] - 8 -
[0048] The expansion machine is designed to control the compressor, pump, and / or driven machine. An expansion machine equipped with the control concept according to the invention can be used in a variety of applications today. As part of a power plant, the expansion machine allows a heat flow to be converted into high-quality electrical energy through expansion. Economical use can be expected wherever a fluctuating, high-quality heat flow is generated. Turbomachines, such as turbines, have significant disadvantages regarding efficiency, especially with fluctuating heat supply. The potential dynamics of the expansion machine allow a wide range of power or driven machines to be driven as needed.
[0049] In another aspect, the present invention relates to a power plant. The power plant comprises a power engine system according to one of the embodiments described above or below and a device for supplying a working medium. The working medium comprises a predetermined quantity of thermal energy. The working medium supplied by the device can thus be fed to the expansion engine in order to transfer its thermal energy to the working piston in the working chamber, enabling the working piston to perform mechanical work.
[0050] The power plant can be designed as a solar thermal power plant, ship propulsion system, or industrial power plant.
[0051] The expansion machine according to the invention can therefore be used in decentralized, solar power plants with concentrating solar thermal energy. Very high temperatures can be achieved in these applications. Furthermore, direct steam generation (using only one working medium) results in a highly fluctuating and dynamic heat flow. For this, the use of a turbomachine is not optimal. Here, a robust and efficient expansion machine in the form of a steam engine can offer decisive advantages.
[0052] The use of residual heat in large mobile applications, such as shipping, is also possible. Ship propulsion systems will only be electrifiable to a small extent in the future. Therefore, a high-quality and fluctuating heat flow will be available in this application. Current ship propulsion systems utilize exhaust gas heat energy with ORC systems. However, these are significantly inferior to the steam engine concept according to the invention (CRC process), especially with regard to efficiency. In addition, the expansion engine according to the invention offers a significant advantage, also in terms of robustness. A25302DE
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[0054] Furthermore, the utilization of industrial process heat is possible. Many industrial processes are subject to significant fluctuations (demand, weather, etc.). This can lead to inefficient conversion of the resulting heat into electricity. Examples include the chemical industry, glass / steel production, food processing, and others. All these processes are conceivable applications where the control concept according to the invention (piston expansion engine in the CRC process) offers significant advantages over current heat-to-electricity conversion (mostly ORC systems with turbomachines).
[0055] The term "expansion engine," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a power engine in which the expansion of gas or steam causes usable mechanical work to be performed. The pressurized steam or gas converts the thermal energy (also known as pressure energy) it contains into kinetic energy by moving a piston within a cylinder. Typically, the piston is part of a crankshaft mechanism, which converts the reciprocating motion of the piston into the rotation of a flywheel that drives the working engine. In this process, the cylinders of an expansion engine are only pressurized with steam or gas at the beginning of each piston stroke.Further movement is caused by the expansion of the steam or gas as the pressure decreases. This allows for significantly better utilization of the energy stored in the steam or gas.
[0056] The term "working space," as used here, is a broad term and should be understood in its usual and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a cavity in which a piston performs mechanical work.
[0057] The term "piston," as used here, is a broad term to which its ordinary and common meaning, as understood by a person skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a movable component which, together with the surrounding housing, the so-called cylinder, forms a closed cavity whose volume changes as a result of the movement.
[0058] - 10 -
[0059] The term "control element," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a movable part of an expansion engine that causes the inflow of steam or gas into and outflow from the cylinder. Through the alternation between inflow and outflow mediated by the control element, the steam or gas in the cylinder can perform work and move the piston back and forth. The control element influences the operation and direction of movement of the expansion engine by opening or closing the inlet and outlet ports. The control element can, for example, be designed in the form of a control piston or a control valve.
[0060] The term "deflection," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to at least one change of direction of a flowing fluid medium.
[0061] The term "piston ring," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a sealing element on a piston. Piston rings have several functions, including sealing the working chamber in which the piston is located from the surrounding housing.
[0062] The term "control edge," as used here, is a broad term and should be understood in its ordinary and common sense, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to that part of a control element, such as a control piston or control valve, which closes or opens the inlet port into the working chamber of the cylinder.
[0063] The term "sliding crank mechanism," as used here, is a broad term to which its ordinary and common meaning, as understood by a person skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a linkage mechanism, such as the A25302DE.
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[0065] This is used to convert a rotary motion into an oscillating linear motion, or vice versa. The linear element is typically a piston that moves back and forth within a cylinder. The coupling is the connecting rod, which links the piston to a rotating shaft or other rotating component.
[0066] The term "gear ratio," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to a specific or adapted meaning. Without restriction, the term can refer in particular to the quotient of the rotational speed of the power machine (gearbox input) and the rotational speed of the driven machine (gearbox output). The quotient of these two values is the dimensionless gear ratio, denoted by the symbol i. When i > 1, the rotational speed is reduced, but the transmitted torque is increased. In everyday language, i > 1 is referred to as a reduction gear or a slower gear ratio, and i < 1 as a faster gear ratio.
[0067] The term "power machine system," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a system comprising at least one expansion machine and at least one working machine.
[0068] The term "working machine," as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to a specific or adapted meaning. Without restriction, the term can refer in particular to a driven machine that absorbs energy in the form of mechanical work. It is the counterpart to the drive or motor, also called a power machine, which outputs mechanical energy. In conjunction with the drive, the working machine is sometimes also referred to as the output. The working machine is connected to the drive via a mechanism. This is often a rotating shaft. However, other forms such as linkages, levers, ropes, and belts are also possible. A clutch can be used to disconnect the power machine and the working machine. Gearboxes can also be used for transmission.Working machines generate electricity or convey, crush, deform, compact, mix, or sieve solids. Some machines can both absorb and release energy; they can switch between power and working functions. Examples include the flywheel, the pump turbine, and the motor-generator. Working machines that transfer the absorbed energy to a fluid—a liquid or a gas—belong to A25302DE.
[0069] - 12 -
[0070] Fluid energy machines. Examples include pumps, compressors, blowers, and fans. Fluid energy machines can also be power machines that extract energy from the fluid, which is then delivered as mechanical work. The expansion machine according to the invention forms the power machine for driving the working machine. Accordingly, the expansion machine is not intended as a drive for a mobile application (ship, locomotive, or other).
[0071] The term "power plant," as used here, is a broad term to which its usual and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to a specific or adapted meaning. Without restriction, the term can refer in particular to a technical facility for generating electricity and, in some cases, also provides thermal energy. In a power plant, mechanical energy is converted into electrical energy by means of generators, which is then fed into the power grid. The mechanical energy to drive the generators, in turn, originates from kinetic energy (hydropower and wind power plants) or thermal energy (via, for example, steam turbines, gas turbines, or ORC turbines).The thermal energy comes from solar radiation energy (solar thermal power plant), geothermal energy (geothermal power plant), chemical energy (burning of coal (coal-fired power plant), petroleum (oil-fired power plant), natural gas (gas-fired power plant), biomass (biomass power plant), waste) or nuclear energy (nuclear power plant, possibly, in the future nuclear fusion).
[0072] The term “predetermined quantity of thermal energy,” as used here, is a broad term to which its ordinary and common meaning, as understood by those skilled in the art, should be attributed. The term is not limited to any specific or adapted meaning. Without limitation, the term can refer in particular to a quantity of thermal energy sufficient to effect the performance of usable mechanical work in an expansion engine through the expansion of gas or steam.
[0073] Brief description of the characters
[0074] Further details and features will become apparent from the following description of exemplary embodiments, particularly in conjunction with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments. The exemplary embodiments are shown schematically in the figures. (Same reference numeral in A25302DE)
[0075] - 13 -
[0076] The individual figures denote elements that are identical or functionally equivalent, or that correspond to each other in terms of their functions.
[0077] Specifically, we show:
[0078] Figure 1 shows a schematic representation of an expansion machine according to an embodiment of the present invention;
[0079] Figure 2 shows a schematic representation of a conventional control concept for an expansion machine;
[0080] Figure 3 shows a schematic representation of a control concept for the expansion machine according to the invention;
[0081] Figure 4 shows another schematic representation of the expansion machine and
[0082] Figures 5A to 5C show a schematic representation of the expansion machine according to a further embodiment in different positions of the control piston.
[0083] Description of the exemplary implementations
[0084] Figure 1 shows a schematic representation of an expansion engine 100 according to an embodiment of the present invention. The expansion engine 100 can, by way of example, be a steam engine. The expansion engine 100 has at least one cylinder 102. The cylinder 102 defines a working chamber 104. The cylinder 102 has an inlet opening 106 for introducing a working medium into the working chamber 104 and an outlet opening 108 for releasing the working medium from the working chamber 104. The working medium can be steam, a gas, or a gas mixture.
[0085] The expansion machine 100 has a working piston 110 which is arranged to move back and forth within the cylinder 102. Specifically, the working piston 110 is arranged to move linearly back and forth within the cylinder 102. More precisely, the working piston 110 is arranged to move harmonically, and in particular sinusoidally, back and forth within the cylinder 102. The reciprocating motion of the working piston 110 changes the volume of the working chamber 104; that is, the volume of the working chamber 104 increases sinusoidally.
[0086] - 14 -
[0087] smaller. Thus, the expansion machine 100 has a first sliding crank mechanism 112. The working piston 110 is movable back and forth by means of the first sliding crank mechanism 112. The working piston 110 thus serves as the thrust element of the first sliding crank mechanism 112. A first connecting rod 114 is provided as a coupling, which connects the working piston 110 to a first rotating component 116. The first connecting rod 114 can, for example, be a first crosshead-guided connecting rod. The first rotating component 116 can be a first gear 118.
[0088] The expansion machine 100 has a control element 120. The control element 120 is designed for selectively opening and closing the inlet opening 106. The control element 120 is designed as a control piston 122. Alternatively, the control element 120 can be designed as a control slide. The control element 120 is arranged to move back and forth outside the cylinder 102. For example, the control element 120 is arranged in a control cylinder 124. The expansion machine 100 also has a second sliding crank mechanism 126. The control element 120 serves as the push member of the second sliding crank mechanism 126. A second connecting rod 128 is provided as a coupling, connecting the control element 120 to a second rotating component 130. The second connecting rod 128 can, for example, be a second crosshead-guided connecting rod. The second rotating component 128 can be a second gear 132.
[0089] The movements of the working piston 110 and the control element 120 are coordinated such that the speed of the control element 120 is half the speed of the working piston 110. In other words, the speed of the control element 120 during movement is always half the speed of the working piston 110 during movement, regardless of the absolute speeds. The first sliding crank mechanism 112 and the second sliding crank mechanism 126 are connected to each other by means of the first gear 118 and the second gear 132. By appropriately designing the first gear 118 and the second gear 132, a transmission ratio of i = 1:2 is achieved between the first sliding crank mechanism 112 and the second sliding crank mechanism 126.
[0090] The push-pull mechanism 112 is a mechanical connection between the working piston 110 and the control element 120. This can also be replaced by the use of other actuator principles. Thus, the control element 120 can also be electrically or pneumatically actuated.
[0091] - 15 -
[0092] or hydraulic actuators. The movement behavior of the control element 110, i.e., half the frequency of the working piston 110, cannot be changed by altering the actuator principle.
[0093] The expansion machine 100 has an exhaust element 134. The exhaust element 134 is designed for selectively opening and closing the exhaust port 108. The exhaust element 134 is designed as an exhaust piston 136. Alternatively, the exhaust element 134 can be designed as an exhaust slide. The exhaust element 134 is arranged to move back and forth outside the cylinder 102. For example, the exhaust element 134 is arranged in an exhaust cylinder 138. The expansion machine 100 also has a third sliding crank mechanism 140. The exhaust element 134 serves as the push member of the third sliding crank mechanism 140. A third connecting rod 142 is provided as a coupling, connecting the exhaust element 134 to a third rotating component 144. The third connecting rod 142 can, for example, be a third crosshead-guided connecting rod. The third rotating component 144 can be a third gear 146.
[0094] The movements of the working piston 110 and the exhaust element 134 are coordinated such that the speed of the exhaust element 134 is exactly the same as the speed of the working piston 110. The first sliding crank mechanism 112 and the third sliding crank mechanism 140 are connected to each other by means of the first gear 118 and the third gear 146. By appropriately designing the first gear 118 and the third gear 146, a gear ratio of i = 1:1 is achieved between the first sliding crank mechanism 112 and the third sliding crank mechanism 140. However, it is explicitly stated that by appropriately designing the first gear 118 and the third gear 146, a gear ratio of i = 1:2 between the first sliding crank mechanism 112 and the third sliding crank mechanism 140 can also be achieved.
[0095] The expansion machine 100 can be modified as follows. The first sliding crank mechanism 112 and the second sliding crank mechanism 126 can be connected to each other by means of a toothed belt or a timing chain. The control element 120 can be driven separately from the working piston 110. The control concept according to the invention can also be implemented with a double-acting working piston.
[0096] Figure 2 shows a schematic representation of a conventional control concept for an expansion machine. Time t is plotted on the X-axis (148). The Y-axis (150A25302DE)
[0097] - 16 -
[0098] The position of the control element at a given time is plotted. Curve 152 shows the temporal evolution of the control element's position. As can be seen in Figure 2, the conventional control element performs a harmonic or sinusoidal motion. The control element moves at the same speed as the working piston. The control element has only one control edge 154. At an exemplary first time tl, shortly before a reversal point 156, the control element opens the inlet opening, and at a second time t2, later than the first time tl, shortly after the reversal point 156, the control element closes the inlet opening. The harmonic oscillation or motion results in very smooth and durable machine operation. However, as schematically illustrated in Figure 2, the slope of the sine function of the control element's motion is very small for short opening durations, i.e., near the reversal point 156.This leads to very slow opening valves and therefore to high throttling losses.
[0099] Figure 3 shows a schematic representation of a control concept for the expansion machine 100 according to the invention. Time t is plotted on the X-axis 148. The position of the control element 120 at a given time is plotted on the Y-axis 150. The curve 152 indicates the temporal progression of the position of the control element 120. As can be seen in Figure 3, the control element 120 performs a harmonic or sinusoidal motion. The control element 120 moves at half the speed of the working piston 110. At an exemplary first time tl before a first zero point 158, the control element 120 opens the inlet opening 106, and at a second time t2, which is later than the first time tl after the first zero point 158, the control element 120 closes the inlet opening 106.Due to the control element 120's speed being half that of the working piston 110, the control element 120 opens the inlet opening 106 again at an exemplary third time t3 after the second time t2 and before a second zero point 160, and the control element 120 closes the inlet opening 106 at a fourth time t4 after the second zero point 160, which is later than the third time t3. The control concept according to the invention is based on the finding that the sinusoidal function of the movement of the control element 120 also has regions with very high gradients or slopes, which, however, occur around the zero point. In order to be able to use these times for valve actuation, the invention provides that the travel speed, i.e., the rotational speed of the control element 120, is halved relative to the working piston 110. This is shown schematically in Figure 3.This results in a first control edge 162 and a second control edge A25302DE.
[0100] - 17 -
[0101] The 164 sensors, each opening during forward movement and closing during backward movement, and vice versa, enable high opening speeds and low throttling losses with short opening times. Simultaneously, the advantages of harmonic and minimally accelerating component excitation are achieved.
[0102] Figure 4 shows a further schematic representation of the expansion machine 100. Figure 4 shows preferred details of the expansion machine 100 and, in particular, of the control element 120. The control cylinder 124 defines a control chamber 166 in which the control element 120, or the control piston 122, is arranged to move back and forth. The control chamber 166 has an inlet opening 168 for the working medium to enter the control chamber 166 and an outlet opening 170 for the working medium to exit the control chamber 166. The outlet opening 170 is fluidly connected to the inlet opening 106 in the working chamber 104. The inlet opening 168 and the outlet opening 170 are arranged with an offset 172 relative to each other in the axial direction of the control cylinder 124. The control piston 122 has a piston recess 174. The piston recess 174 is formed, for example, in an axial center of the control piston 122.Accordingly, the control piston 122 has a first control piston part 176 and a second control piston part 178. A first piston ring 180a and a second piston ring 182a are arranged circumferentially around the control piston 122 on the first control piston part 176. The first piston ring 180a and the second piston ring 182a are spaced apart axially. The first piston ring 180a and the second piston ring 182a are designed as seals. Similarly, a first piston ring 180b and a second piston ring 182b are arranged circumferentially around the control piston 122 on the second control piston part 178. The first piston ring 180b and the second piston ring 182b are spaced apart axially. The first piston ring 180b and the second piston ring 182b are designed as seals.The first piston ring 180a of the first control piston section 176 and the first piston ring 180b of the second control piston section 178 face each other, whereas the second piston ring 180a of the first control piston section 176 and the second piston ring 182b of the second control piston section 178 face away from each other. The control piston 122 is slightly spaced from a wall 184 of the control cylinder 124, so that a gap 186 is formed between the control piston 122 and the wall 184 of the control cylinder 124 to prevent the control piston 122 from jamming. The sealing of the working medium is achieved via the piston rings 180, 180b, 182a, and 182b. Due to the axial offset 172 between inlet opening 168 and outlet opening 170, the control chamber 166 is such A25302DE.
[0103] - 18 -
[0104] designed so that the working medium undergoes at least one deflection on a flow path from the inlet opening 168 to the outlet opening 170.
[0105] Figures 5A to 5C show a schematic representation of the expansion machine 100 according to a further embodiment in various positions of the control piston 122. Only the differences from the embodiment shown in Figures 1 to 4 are described below, and identical or comparable components and features are designated with the same reference numerals. In the embodiment shown in Figures 5A to 5C, the control piston 122 is hollow. Accordingly, the control piston 122 defines an interior space 188. The working medium can enter the interior space 188 from at least one axial end 190 of the control piston 122, as indicated by an arrow 192. The interior space 188 is fluidically connected to the piston recess 174. Furthermore, the control cylinder 124 has a first inlet opening 168a and a second inlet opening 168b.The first inlet opening 168a, the second inlet opening 168b, and the outlet opening 170 are each arranged with an offset 172 in the axial direction of the control cylinder 124 relative to one another. Due to the axial offset 172 between the inlet openings 168a, 168b, and the outlet opening 170, the control chamber 166 is configured such that the working medium undergoes at least one deflection on its flow path from the inlet openings 168a, 168b to the outlet opening 170.
[0106] Figure 5A shows the control piston 122 in a first closed position. In this first closed position, the control piston 122 is located on the left side of the control chamber 166. Between the first piston ring 180b and the second piston ring 182b of the second control piston section 178, there is a space 194 in the axial direction. This space does not have a sealing function and therefore does not impede the flow of a linearly moving working medium. In the first closed position, the first piston ring 180b of the second control piston section 178 has passed over the outlet opening 170. This prevents fluid communication between the inlet openings 168a, 168b or the interior space 188 and the outlet opening 170 via the piston recess 174, thus fluidically separating them.
[0107] Figure 5B shows the control piston 122 in an open position. In the open position, the control piston 122 is in a position where the piston recess 174 and the outlet opening 170 are aligned and thus fluidly connected. (According to A25302DE)
[0108] - 19 -
[0109] The working medium can enter the interior 166 from the inlet openings 168a, 168b and exit the control chamber through the piston recess 174 and the outlet opening 170, whereby the working medium is deflected twice.
[0110] Figure 5C shows the control piston 122 in a second closed position. In this second closed position, the control piston 122 is located on the right side of the control chamber 166. Between the first piston ring 180a and the second piston ring 182a of the first control piston section 176, there is a chamber 194 that does not provide a seal and therefore does not impede the flow of a linearly moving working medium. In the first closed position, the first piston ring 180a of the first control piston section 176 has passed over the outlet opening 170. This prevents fluid communication between the inlet openings 168a, 168b or the interior space 188 and the outlet opening 170 via the piston recess 174, thus fluidically separating them.
[0111] The expansion machine 100 according to the invention can be part of a power machine system (not shown in detail) comprising at least one generator configured to generate electrical energy, a compressor, a pump, and / or a working machine, and at least one such expansion machine 100. The expansion machine 100 according to the invention can also be part of such a power machine system, which is not shown in detail and includes a device for providing a working medium with a predetermined amount of thermal energy. For example, the power plant comprises at least one generator configured to generate electrical energy and at least one such expansion machine 100. The expansion machine 100 is configured to drive the generator. For instance, the first crankshaft drive 112 can be connected to a drive shaft of the generator.The mechanical force generated by the working piston 110 during the expansion of the working medium in the working chamber 104 is transmitted via the first crankshaft drive 112 to the drive shaft of the generator or an intermediate gearbox. By driving the piston, the generator produces electrical energy, such as electric current. The power plant, in turn, can be configured as a solar thermal power plant, a ship propulsion system, or an industrial power plant. A25302DE.
[0112] - 20 -
[0113] Reference symbol list
[0114] 100 Expansion machine
[0115] 102 cylinders
[0116] 104 workroom
[0117] 106 Entrance
[0118] 108 Outlet opening
[0119] 110 working pistons
[0120] 112 first push-crank mechanism
[0121] 114 first connecting rod
[0122] 116 first rotating component
[0123] 118 first gear
[0124] 120 control element
[0125] 122 control pistons
[0126] 124 control cylinders
[0127] 126 second push-crank mechanism
[0128] 128 second connecting rod
[0129] 130 second rotating component
[0130] 132 second gear
[0131] 134 Outlet element
[0132] 136 exhaust pistons
[0133] 138 exhaust cylinders
[0134] 140 third push-crank mechanism
[0135] 142 third connecting rod
[0136] 144 third rotating component
[0137] 146 third gear
[0138] 148 X-axis
[0139] 150 Y-axis
[0140] 152 temporal evolution of the control element's location 154 control edge
[0141] 156 Turning Point
[0142] 158 first zero point
[0143] 160 second zero point
[0144] 162 first control edge
[0145] 164 second control edge
[0146] 166 Control room
[0147] 168 Entrance A25302DE
[0148] - 21 -
[0149] 168a first entrance opening
[0150] 168b second entrance
[0151] 170 Exit opening
[0152] 172 axial offset
[0153] 174 Piston recess
[0154] 176 first control piston part
[0155] 178 second control piston part
[0156] 180a first piston ring
[0157] 180b second piston ring
[0158] 182a first piston ring
[0159] 182b second piston ring
[0160] 184 gap
[0161] 188 Interior
[0162] 190 axial end
[0163] 192 Entry into the working medium
[0164] Room 194
[0165] tl first point in time
[0166] t2 second time point
[0167] t3 third time point
[0168] t4 fourth time point
Claims
A25302DE - 22 - Karlsruhe Institute of Technology, a public corporation, March 26, 2026, KIT25302PC ST / PF / PF Claims 1. Expansion machine (100), comprising at least one cylinder (102) defining a working chamber (104), wherein the cylinder (102) has an inlet opening (106) for introducing a working medium into the working chamber (104) and an outlet opening (108) for releasing the working medium from the working chamber (104), a working piston (110) which is arranged to move back and forth in the cylinder (102), and a control element (120) designed for selectively opening and closing the inlet opening (106), wherein the control element (120) is arranged to be movable back and forth outside the cylinder (102), wherein the movements of the working piston (110) and the control element (120) are coordinated such that the speed of the control element (120) is half the speed of the working piston (110).
2. Expansion machine (100) according to the preceding claim, wherein the working piston (110) and / or the control element (120) are linearly reciprocating.
3. Expansion machine (100) according to one of the preceding claims, wherein the working piston (110) and the control element (120) are harmonically reciprocating.
4. Expansion machine (100) according to one of the preceding claims, wherein the control element (120) is designed as a control piston (122) or control slide.
5. Expansion machine (100) according to the preceding claim, further comprising a control cylinder (124), wherein the control cylinder (124) defines a control chamber (166), wherein the control piston (122) is arranged to be reciprocating in the control chamber (166), wherein the control chamber (166) has at least one inlet opening (168, 168a, 168b) for the working medium to enter the control chamber (166) and an outlet opening (170) for the working medium to exit the control chamber (166) - 23 - exhibits, wherein the control chamber (166) is designed such that the working medium undergoes at least one deflection on a flow path from the inlet opening (168, 168a, 168b) to the outlet opening (170).
6. Expansion machine (100) according to the preceding claim, wherein the inlet opening (168, 168a, 168b) and the outlet opening (170) are arranged with an offset (172) in the axial direction of the control cylinder (124) to each other.
7. Expansion machine (100) according to one of the two preceding claims, wherein the control piston (122) has a first control piston part (176) and a second control piston part (178), wherein a first piston ring (180a) and a second piston ring (182a) are arranged circumferentially around the control piston (122) on the first control piston part (176), wherein the first piston ring (180a) and the second piston ring (182a) are spaced apart axially, wherein a first piston ring (180b) and a second piston ring (182b) are arranged circumferentially around the control piston (122) on the second control piston part (178), wherein the first piston ring (180b) and the second piston ring (182b) are spaced apart axially.
8. Expansion machine (100) according to one of claims 5 to 7, wherein the control piston (122) has a piston recess (174).
9. Expansion machine (100) according to the preceding claim, wherein the control piston (122) defines an interior space (188), wherein the interior space (188) is fluidly connected to the piston recess (174).
10. Expansion machine (100) according to one of the preceding claims, wherein the control element (120) has a first control edge (162) and a second control edge (164), wherein the first control edge (162) and the second control edge (164) are configured to open the inlet opening (106) during a forward movement and to close the inlet opening (106) during a backward movement and vice versa.
11. Expansion machine (100) according to one of the preceding claims, further comprising at least a first push-crank gear (112) and a second push-crank gear (A25302DE) - 24 - belgetriebe (126), wherein the working piston (110) is movable back and forth by means of the first sliding crank mechanism (112), wherein the control element (120) is movable back and forth by means of the second sliding crank mechanism (126), wherein the first sliding crank mechanism (112) and the second sliding crank mechanism (126) are connected to each other in such a way that a rotational speed of the second sliding crank mechanism (126) is half as large as a rotational speed of the first sliding crank mechanism (112).
12. Expansion machine (100) according to the preceding claim, wherein the transmission ratio of the first sliding crank mechanism (112) and the second sliding crank mechanism (126) is i = 1:
2.
13. Expansion machine (100) according to one of the two preceding claims, wherein the first sliding crank mechanism (112) and the second sliding crank mechanism (126) are connected to each other by means of gears (118, 132), a toothed belt or a timing chain.
14. Expansion machine (100) according to one of claims 1 to 10, wherein the control element (120) can be driven separately from the working piston (110), in particular by an electric, hydraulic or pneumatic actuator.
15. Expansion machine (100) according to one of the preceding claims, wherein the expansion machine (100) is designed as at least one expansion machine (100) from the group consisting of: steam engine, refrigeration machine.
16. Power engine system, comprising at least one generator designed to produce electrical energy, a compressor, a pump and / or a working machine and at least one expansion machine (100) according to one of the preceding claims, wherein the expansion machine (100) is designed to drive the generator, the compressor, the pump and / or the working machine.
17. Power plant comprising a power engine system according to the preceding claim and a device for providing a working medium having a predetermined amount of thermal energy. A25302DE - 25 - 18. Power plant according to the preceding claim, wherein the working medium is gas or steam.
19. Power plant according to one of the two preceding claims, wherein the power plant is designed as a solar thermal power plant, ship propulsion or industrial power plant.