Stirling engine and heat pump system

Abstract

Provided in the present application are a Stirling engine and a heat pump system. The Stirling engine comprises at least: a housing, which is provided with an accommodating cavity; a first heat exchanger, which is disposed in a first end of the accommodating cavity; a second heat exchanger, which is disposed in a second end of the accommodating cavity; a regenerator, which is arranged in the accommodating cavity and is located between the first heat exchanger and the second heat exchanger; and a first piston, which is arranged in the first end and is located on the side of the first heat exchanger facing away from the regenerator, the first piston being in sealed fit with the inner side wall of the first end, and a first pressure cavity being formed between the first piston and the first heat exchanger. The first piston is provided with a first buffer cavity, and the side of the first piston facing the first heat exchanger is provided with a gas-passing mechanism that is in communication with the first buffer cavity and the first pressure cavity, and the first piston is configured to adjust the air pressure in the first pressure cavity by means of the gas-passing mechanism and the first buffer cavity. In this way, the present application can improve the heat pumping efficiency and energy efficiency of the Stirling engine.

Description

Stirling engines and heat pump systems

[0001] This application claims priority to Chinese patent application No. 202510100319.X, filed on January 21, 2025, entitled “Stirling Heat Engine and Heat Pump System”, which is incorporated herein by reference in its entirety. [Technical Field]

[0002] This application relates to the field of heat pump technology, and in particular to a Stirling engine and a heat pump system. [Background Technology]

[0003] A traditional Stirling engine typically consists of a compression piston, an expansion piston, a hot-end heat exchanger, a cold-end heat exchanger, and a regenerator. The compression piston and the expansion piston reciprocate at a certain phase angle, and thermo-acoustic conversion occurs in the regenerator, forming a temperature gradient in the regenerator, pumping heat from the low-temperature end to the high-temperature end.

[0004] In related technologies, during the entire cycle of the working fluid in a Stirling engine, the compression piston and expansion piston rely on the crankshaft, connecting rod, and piston rod to convert the motor rotation into the piston's axial reciprocating motion. However, the mechanical efficiency of the axial reciprocating motion of the compression and expansion pistons is low. Furthermore, during the compression and expansion phases of the entire cycle, the two pistons need to overcome inertial forces, which leads to increased power consumption and decreased pumping efficiency. [Summary of the Invention]

[0005] This application provides a heat pump system to improve the heat pumping efficiency and energy efficiency of a Stirling engine.

[0006] To solve the above-mentioned technical problems, one technical solution adopted in this application is: providing a Stirling engine, the Stirling engine comprising at least: a shell with a receiving cavity; a first heat exchanger disposed at a first end of the receiving cavity; a second heat exchanger disposed at a second end of the receiving cavity; a regenerator disposed in the receiving cavity and located between the first heat exchanger and the second heat exchanger; a first piston disposed at the first end and located on the side of the first heat exchanger opposite to the regenerator, the first piston being sealed to the inner wall of the first end, and a first pressure chamber being formed between the first piston and the first heat exchanger; wherein, the first piston is provided with a first buffer chamber, and the side of the first piston facing the first heat exchanger is provided with a venting mechanism that communicates with the first buffer chamber and the first pressure chamber respectively, for adjusting the air pressure in the first pressure chamber through the venting mechanism and the first buffer chamber.

[0007] In some embodiments, the venting mechanism includes a throttling orifice formed in the first piston, which communicates with the first buffer chamber and the first pressure chamber, respectively.

[0008] In some embodiments, the ventilation mechanism includes: a one-way air intake mechanism, which guides the working fluid in the first pressure chamber to the first buffer chamber when the pressure difference between the first pressure chamber and the first buffer chamber is greater than a first pressure threshold; and a one-way air outlet mechanism, which guides the working fluid in the first buffer chamber to the first pressure chamber when the pressure difference between the first buffer chamber and the first pressure chamber is greater than a second pressure threshold.

[0009] In some embodiments, the second heat exchanger is spaced apart from the end wall of the second end to form a second buffer cavity between the end of the second heat exchanger away from the regenerator and the end wall of the second end.

[0010] In some embodiments, the Stirling engine further includes a third heat exchanger disposed within the housing cavity and located between the first piston and the first heat exchanger.

[0011] In some embodiments, the Stirling engine includes two first pistons, respectively disposed in the first end and the second end, and the first piston located in the second end is sealed to the inner wall of the second end.

[0012] In some embodiments, the volume of the first buffer chamber of the first piston located at the first end is greater than or equal to the volume of the first buffer chamber of the first piston located at the second end.

[0013] In some embodiments, the motion phase of the first piston located in the second end precedes the motion phase of the first piston located in the first end.

[0014] In some embodiments, the Stirling engine further includes a second piston disposed within the second end; during the isothermal compression phase of the Stirling engine, the second piston moves toward the first heat exchanger to an equilibrium position, and the venting mechanism on the first piston is in a closed state; during the isobaric heat release phase of the Stirling engine, the second piston continues to move from the equilibrium position toward the first heat exchanger, and the venting mechanism on the first piston is in an intake state; during the isothermal expansion phase of the Stirling engine, the first piston moves away from the second heat exchanger to a limit position, and the venting mechanism on the first piston is in a closed state; during the isobaric heat absorption phase of the Stirling engine, the second piston moves away from the equilibrium position toward the first heat exchanger, the first piston moves toward the second heat exchanger, and the venting mechanism on the first piston is in an exhaust state.

[0015] In some embodiments, the Stirling engine further includes: a piston rod connected to the side of the first piston away from the first heat exchanger; wherein the piston rod has a hollow cavity communicating with the first buffer chamber.

[0016] In some embodiments, the throttling orifice is located at the center of the side of the first piston near the first heat exchanger.

[0017] To solve the above-mentioned technical problems, one technical solution adopted in this application is to propose a heat pump system, including the Stirling engine mentioned above.

[0018] The beneficial effects of this application are as follows: The Stirling engine provided by this application includes at least a first heat exchanger, a second heat exchanger, a regenerator, and a first piston disposed within a housing cavity formed by the shell; wherein, the first piston is disposed within a first end and located at the end of the first heat exchanger opposite to the regenerator, the outer edge of the first piston is sealed to the inner wall of the first end, and a first pressure chamber is formed between the first piston and the first heat exchanger; the first piston is provided with a first buffer chamber, and a venting mechanism is provided on the side of the first piston facing the first heat exchanger, which is respectively connected to the first buffer chamber and the first pressure chamber, for adjusting the air pressure in the first pressure chamber through the venting mechanism and the first buffer chamber. In this way, on the one hand, this application utilizes the first buffer chamber formed within the first piston as a working fluid buffer space for the first pressure chamber. Combined with the venting mechanism, the gas pressure within the first pressure chamber can be adjusted, thus enabling alternating motion of the working fluid between the first and second ends of the chamber. This creates a temperature gradient in the regenerator, achieving heat pumping from the low-temperature end to the high-temperature end. On the other hand, through improvements to the piston structure, this application allows for the adjustment of the gas pressure within the first pressure chamber via the venting mechanism and the first buffer chamber within the first piston. Compared to existing methods that rely solely on the axial reciprocating motion of the piston relative to the piston cylinder to adjust the gas pressure, this application's venting mechanism offers higher operational efficiency, improving the mechanical efficiency of the Stirling engine. Furthermore, the first buffer chamber, as a buffer space for the first pressure chamber, allows for faster and more precise adjustment of the system's pressure and velocity waves. It also addresses the problem of inefficient work done by the piston during working fluid compression and expansion due to inertial forces, optimizing the working fluid circulation pattern. Therefore, this application can improve the heat pumping efficiency and energy efficiency of the Stirling engine. [Attached Image Description]

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0020] Figure 1 is a schematic diagram of the structure of an embodiment of the Stirling engine of this application;

[0021] Figure 2 is a schematic cross-sectional view of the embodiment in Figure 1 along AA;

[0022] Figure 3 is a cross-sectional structural schematic diagram of another embodiment of the Stirling heat engine of this application;

[0023] Figure 4 is a structural schematic diagram of yet another embodiment of the Stirling engine of this application;

[0024] Figure 5 is a structural schematic diagram of another embodiment of the Stirling engine of this application;

[0025] Figure 6 is a schematic diagram of the state structure of the Stirling engine in the isothermal compression stage of this application.

[0026] Figure 7 is a schematic diagram of the state structure of the Stirling heat engine in the isobaric exothermic stage of this application.

[0027] Figure 8 is a schematic diagram of the state structure of the Stirling heat engine in the isothermal expansion stage of this application.

[0028] Figure 9 is a schematic diagram of the state structure of the Stirling heat engine in the isobaric heat absorption stage of this application;

[0029] Figure 10 is a schematic diagram of the ideal waveform of the pressure-volume change of the Stirling heat engine;

[0030] Figure 11 is a waveform diagram of the actual pressure-volume change of the Stirling engine in this application;

[0031] Figure 12 is a waveform diagram of the actual pressure-volume change of the Stirling heat engine in the relevant technology.

Detailed Implementation Methods

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0034] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0035] A traditional Stirling engine typically consists of a compression piston, an expansion piston, a hot-end heat exchanger, a cold-end heat exchanger, and a regenerator. The compression piston and the expansion piston reciprocate at a certain phase angle, and thermo-acoustic conversion occurs in the regenerator, forming a temperature gradient in the regenerator, pumping heat from the low-temperature end to the high-temperature end.

[0036] In related technologies, during the entire cycle of the working fluid in a Stirling engine, the compression piston and expansion piston are converted from the rotation of the motor into the reciprocating motion of the piston along the axial direction by the crankshaft, connecting rod, and piston rod. However, the mechanical efficiency of the reciprocating motion of the compression piston and expansion piston along the axial direction is lower.

[0037] Furthermore, throughout the entire cycle, the compression piston and expansion piston need to overcome inertial forces during the compression and expansion phases, leading to increased power consumption and decreased pump efficiency. This issue becomes a bottleneck for improving overall system performance. Additionally, traditional piston phase angles and system cycle pressure ratios are fixed values, resulting in a significant temperature gradient distribution within the system. The alternating piston motion causes alternating motion of the working fluid, and system pressure and velocity fluctuations create a phase difference due to temperature distribution and component flow resistance, leading to a decrease in heating capacity and system energy efficiency.

[0038] Therefore, this application first proposes a Stirling engine, as shown in Figure 1, which is a structural schematic diagram of an embodiment of the Stirling engine of this application; Figure 2 is a cross-sectional structural schematic diagram of the embodiment of Figure 1 along line AA. The Stirling engine 10 of this embodiment includes at least: a casing 110, a first heat exchanger 120, a second heat exchanger 130, a regenerator 160, and a first piston 140; wherein, the casing 110 has a receiving cavity (not shown); the first heat exchanger 120 is disposed in the first end of the receiving cavity; the second heat exchanger 130 is disposed in the second end of the receiving cavity; the regenerator 160 is disposed in the receiving cavity and located between the first heat exchanger 120 and the second heat exchanger 130; the first piston 140 is disposed in the first end and located between the first and second heat exchangers 120 and 130. A heat exchanger 120 is located on the side away from the regenerator 160; a first piston 140 is sealed to the inner wall of the first end of the receiving cavity, and a first pressure chamber A1 is formed between the first piston 140 and the first heat exchanger 120; the first piston 140 is provided with a first buffer chamber C1, and a venting mechanism 150 is provided on the side of the first piston 140 facing the first heat exchanger 120, which is connected to the first buffer chamber C1 and the first pressure chamber A1 respectively, for adjusting the air pressure in the first pressure chamber A1 through the venting mechanism 150 and the first buffer chamber C1.

[0039] The first piston 140 can reciprocate along the axial direction X of the receiving cavity within the first end, i.e., the arrangement direction of the first heat exchanger 120, the second heat exchanger 130, and the regenerator 160, to adjust the gas pressure in the first pressure chamber A1, thereby realizing the alternating motion of the working fluid in the receiving cavity between the first end and the second end, thus forming a temperature gradient in the regenerator 160 and realizing heat pumping from the low temperature end to the high temperature end.

[0040] The first end of the receiving cavity is provided with an end wall and an inner side wall. The first piston 140 is sealed to the inner side wall of the first end of the receiving cavity and is relatively movable to improve the efficiency of the reciprocating motion of the first piston 140 in regulating the air pressure in the first pressure chamber A1. Specifically, the outer peripheral wall of the first piston 140 along the axial direction X, i.e., the outer edge, is sealed to the inner side wall of the first end.

[0041] On the one hand, in this embodiment, a first buffer chamber C1 is formed within the first piston 140, and the first buffer chamber C1 is used as a working fluid buffer space for the first pressure chamber A1. Combined with the ventilation mechanism 150, the gas pressure within the first pressure chamber A1 can be adjusted, thus enabling alternating motion of the working fluid between the first and second ends of the chamber, thereby creating a temperature gradient in the regenerator 160 and achieving heat pumping from the low-temperature end to the high-temperature end. On the other hand, this embodiment improves the structure of the first piston 140, and through the ventilation mechanism 150 and the first buffer chamber within the first piston 140… The first pressure chamber A1 can be adjusted by chamber C1. Compared to existing methods that only adjust the pressure in the first pressure chamber by the axial reciprocating motion of the piston relative to the piston cylinder, the ventilation mechanism 150 in this embodiment has high operating efficiency, which can improve the mechanical efficiency of the Stirling engine 10. Furthermore, the first buffer chamber C1, as a buffer space for the first pressure chamber A1, can adjust the pressure and velocity waves of the system more quickly and accurately, increasing the phase adjustment capability. It can also improve the problem of inefficient work done by the working fluid due to inertial force during compression and expansion, and optimize the working fluid circulation pattern. Therefore, this embodiment can improve the pumping efficiency and energy efficiency of the Stirling engine 10.

[0042] In some embodiments, within the receiving cavity formed by the housing 110, the first heat exchanger 120, the regenerator 160, and the second heat exchanger 130 are sequentially arranged in contact to increase heat transfer efficiency; and the first heat exchanger 120, the regenerator 160, and the second heat exchanger 130 are arranged sequentially from the first end to the second end.

[0043] In other embodiments, the first heat exchanger, the regenerator, and the second heat exchanger may be arranged alternately.

[0044] In some embodiments, as shown in FIG1 and FIG2, the ventilation mechanism 150 includes a throttling orifice 141 formed in the first piston 140, the throttling orifice 141 being connected to the first buffer chamber C1 and the first pressure chamber A1 respectively.

[0045] In this embodiment, the venting mechanism 150 is implemented by directly setting a throttling orifice 141 on the side of the first piston 140 facing the first heat exchanger 120. This structure is simple and easy to implement, requires no control, and has high reliability. Therefore, this embodiment simplifies the structure of the Stirling engine 10 and improves its reliability.

[0046] In some embodiments, the aperture of the throttling orifice 141 can be set based on at least one of the following parameters: the cross-sectional area of ​​the first pressure chamber A1, the volume of the first pressure chamber A1, the volume of the first buffer chamber C1, and the pressure regulation requirements of the working medium in the first pressure chamber A1.

[0047] In some embodiments, the throttling orifice 141 is located at the center of the first piston 140 on the side near the first heat exchanger 120. This embodiment places the throttling orifice 141 at the center of the first heat exchanger 120, which not only improves the uniformity of structural strength in various regions of the first piston 140 and enhances its reliability, but also balances the uniformity of the working fluid flow within the first buffer chamber C1, thereby improving the buffering effect.

[0048] The center location can be the geometric center. Of course, in other embodiments, the center location can be a middle region, which is set relative to the edge region. For example, the middle region is a circular region with a radius less than one-third of the full radius, and so on.

[0049] In some embodiments, the throttling orifice 141 is located at the top of the first piston 140 or at other locations.

[0050] In some embodiments, as shown in FIG3, FIG3 is a cross-sectional structural schematic diagram of another embodiment of the Stirling heat engine of this application, and the cross-sectional direction can be seen in FIG1; the ventilation mechanism 150 includes a one-way air intake mechanism 142 and a one-way air outlet mechanism 143; when the pressure difference between the first pressure chamber A1 and the first buffer chamber C1 is greater than the first pressure threshold, the one-way air intake mechanism 142 guides the working fluid in the first pressure chamber A1 to the first buffer chamber C1; when the pressure difference between the first buffer chamber C1 and the first pressure chamber A1 is greater than the second pressure threshold, the one-way air outlet mechanism 143 guides the working fluid in the first buffer chamber C1 to the first pressure chamber A1.

[0051] The pressure difference between the first pressure chamber A1 and the first buffer chamber C1 being greater than the first pressure threshold means that the air pressure in the first pressure chamber A1 is greater than the air pressure in the first buffer chamber C1, and the difference between the two is greater than the first pressure threshold. The pressure difference between the first buffer chamber C1 and the first pressure chamber A1 being greater than the second pressure threshold means that the air pressure in the first buffer chamber C1 is greater than the air pressure in the first pressure chamber A1, and the difference between the two is greater than the second pressure threshold.

[0052] The first pressure threshold can be equal to or different from the second pressure threshold, and can be set according to the air pressure adjustment needs in the first pressure chamber A1.

[0053] In some embodiments, the first pressure threshold and the second pressure threshold can be adjusted based on at least one of the following parameters: the cross-sectional area of ​​the first pressure chamber A1, the volume of the first pressure chamber A1, the volume of the first buffer chamber C1, and the working fluid pressure regulation requirements in the first pressure chamber A1.

[0054] The first piston 140 is provided with a first mounting through hole (not shown in the figure) and a second mounting through hole (not shown in the figure) on the side facing the first heat exchanger 120. The one-way air intake mechanism 142 is provided in the first mounting through hole, and the one-way air outlet mechanism 143 is provided in the second mounting through hole.

[0055] In some embodiments, both the one-way inlet mechanism 142 and the one-way outlet mechanism 143 can be implemented using one-way valves. The one-way valve achieves unidirectional flow based on the pressure difference between the working fluid in the first buffer chamber C1 and the working fluid in the first pressure chamber A1. The inlet end of the one-way valve, serving as the one-way inlet mechanism 142, is connected to the first buffer chamber C1, and its outlet end is connected to the first pressure chamber A1; similarly, the inlet end of the one-way valve, serving as the one-way outlet mechanism 143, is connected to the first pressure chamber A1, and its outlet end is connected to the first buffer chamber C1. The one-way valve is internally designed with a valve disc or valve core. When the working fluid enters from the inlet end, pressure acts on the valve disc, and if the pressure difference exceeds the aforementioned threshold, it opens, allowing fluid to pass through. When the fluid attempts to flow in the reverse direction from the outlet end, the valve disc closes under the action of fluid pressure, thereby preventing reverse flow.

[0056] In some embodiments, the central axis of the first mounting through hole and the central axis of the second mounting through hole may coincide with the central axis of the piston 140, and the first mounting through hole and the second mounting through hole are coaxially arranged.

[0057] In some embodiments, the central axis of the first mounting through hole and / or the central axis of the second mounting through hole may also be located above the central axis of the piston 140.

[0058] In some embodiments, as shown in FIG1, the second heat exchanger 130 is spaced apart from the end wall of the second end of the receiving cavity to form a second buffer cavity C2 between the end of the second heat exchanger 130 away from the regenerator 160 and the end wall of the second end.

[0059] The second end of the receiving cavity is provided with an end wall and an inner wall, and the second end is connected to the first end only on the side where the second heat exchanger 130 is located. A second buffer cavity C2 is formed between the end of the second heat exchanger 130 away from the regenerator 160 and the end wall of the second end of the receiving cavity.

[0060] This embodiment further provides a second buffer chamber C2 on the side of the second heat exchanger 130 away from the regenerator 160. This allows for faster and more precise adjustment of pressure and velocity waves, forming a pressure waveform, thereby improving pumping efficiency, increasing phase adjustment capability, and mitigating the problem of inefficient work done by the piston during working fluid compression and expansion due to inertial forces, thus optimizing the working fluid circulation pattern. Therefore, this embodiment can further improve the pumping efficiency and energy efficiency of the Stirling engine 10. Furthermore, the second buffer chamber C2 allows for a spaced-out arrangement between the end walls of the first heat exchanger 120 and the second end, enabling the working fluid to flow through multiple heat exchange channels within the second heat exchanger 130, thereby improving the working fluid flow efficiency and pumping efficiency.

[0061] In some embodiments, as shown in FIG4, FIG4 is a structural schematic diagram of another embodiment of the Stirling engine of this application. The Stirling engine 10 of this embodiment further includes: a third heat exchanger 180, disposed in the receiving cavity and located between the first piston 140 and the first heat exchanger 120.

[0062] In this embodiment, a third heat exchanger 180 is provided in the first end of the receiving cavity, and the third heat exchanger 180 is located on the side of the first piston 140 away from the first heat exchanger 120. The first end can be used as the cold end. By providing the third heat exchanger 180 at the cold end, the heat of the cold end can be increased, the phase adjustment can be accelerated, and the pumping efficiency of the Stirling heat engine 10 can be improved.

[0063] Similar improvements can be made to other embodiments of this application, which will not be elaborated here.

[0064] In some embodiments, as shown in FIG5, FIG5 is a structural schematic diagram of another embodiment of the Stirling engine of this application. The Stirling engine 10 of this embodiment includes two first pistons 140, which are respectively disposed in the first end and the second end of the receiving cavity, and the first piston 140 located in the second end is sealed to the inner sidewall of the second end.

[0065] The first piston 140 located inside the second end is sealed to the inner wall of the second end of the receiving cavity and is movable relative to it, so as to improve the efficiency of the reciprocating motion of the first piston 140 in regulating the air pressure in the second pressure chamber A2. Specifically, the outer peripheral wall of the first piston 140 along the axial direction X, i.e., the outer edge, is sealed to the inner wall of the second end.

[0066] The second pressure chamber A2 is formed between the first piston 140 located at the second end and the second heat exchanger 130.

[0067] On the one hand, this embodiment can utilize the first buffer chamber C1 formed within the first piston 140 located at the second end and the corresponding ventilation mechanism 150 to regulate the gas pressure in the second pressure chamber A2. Therefore, it can realize the alternating motion of the working fluid in the chamber between the first and second ends, thereby forming a temperature gradient in the regenerator and realizing heat pumping from the low-temperature end to the high-temperature end. On the other hand, this embodiment improves the structure of the first piston 140, and the gas pressure in the second pressure chamber A2 can be regulated by the ventilation mechanism 150 and the first buffer chamber C1 within the first piston 140. Compared with the existing method of regulating the gas pressure in the second pressure chamber A2 by the reciprocating motion of the piston relative to the piston cylinder along the axial direction, the ventilation mechanism 150 in this embodiment has high operating efficiency, which can improve the mechanical efficiency of the Stirling engine 10. Moreover, the first buffer chamber C1, as a buffer space for the second pressure chamber A2, can regulate the pressure wave and velocity wave of the system more quickly and accurately, increase the phase adjustment capability, and improve the problem of inefficient work caused by inertial force during the compression and expansion of the working fluid, thereby optimizing the working fluid circulation pattern. Therefore, this embodiment can improve the pumping efficiency and energy efficiency of the Stirling heat engine 10.

[0068] In some embodiments, pistons with the same or different structures may be provided in the first and second ends of the receiving cavity.

[0069] In some embodiments, the volume of the first buffer chamber C1 of the first piston 140 located at the first end is greater than or equal to the volume of the first buffer chamber C1 of the first piston 140 located at the second end. This embodiment provides first buffer chambers C1 of different volumes at both ends of the accommodating cavity, enabling different discharge rates of the working fluid at the cold and hot ends, thereby improving phase adjustment capability.

[0070] In some embodiments, the movement phase of the first piston 140 located in the second end precedes the movement phase of the first piston 140 located in the first end. The second end with the piston movement phase preceding the first end is the hot end of the system, i.e., the compression end, and the first end with the piston movement phase preceding the first end is the cold end of the system, i.e., the expansion end. Setting the buffer space of the expansion end to be larger than that of the compression end can form a more efficient cycle.

[0071] In some embodiments, as shown in Figures 1, 3 and 5, the Stirling engine 10 further includes: a piston rod 170 connected to the side of the first piston 140 away from the first heat exchanger 120; wherein the piston rod 170 is provided with a hollow cavity D1 communicating with the first buffer chamber C1.

[0072] In this embodiment, the piston rod 170 is provided with a hollow cavity D1 that communicates with the first buffer chamber C1, so as to expand the buffer space of the first pressure chamber A1 and increase the phase adjustment range, thereby further improving the pumping efficiency and energy efficiency of the Stirling heat engine 10; or the volume of the piston 140 can be reduced, which is conducive to the miniaturization and lightweight design of the Stirling heat engine 10.

[0073] The piston rod 170 is used to drive the first piston 140 to reciprocate along the axial direction X, thereby improving the stability and operability of the piston 140's movement. One end of the piston rod 170 is connected to the side of the first piston 140 away from the first heat exchanger 120, and the other end of the piston rod 170 can extend outside the receiving cavity to obtain driving force.

[0074] In some embodiments, each first piston 140 is provided with a corresponding piston rod 170. The two piston rods 170 can be driven by the same motor or other driving component, and their speed and rotation direction can be consistent to simplify control and improve mechanical efficiency and pumping efficiency.

[0075] In some embodiments, as shown in Figures 6 to 9, Figure 6 is a schematic diagram of the state structure of the Stirling engine 10 in the isothermal compression stage; Figure 7 is a schematic diagram of the state structure of the Stirling engine 10 in the isothermal heat release stage; Figure 8 is a schematic diagram of the state structure of the Stirling engine 10 in the isothermal expansion stage; and Figure 9 is a schematic diagram of the state structure of the Stirling engine 10 in the isothermal heat absorption stage. The Stirling engine 10 also includes a second piston 60 disposed within the second end. The operating stages of the Stirling engine 10 include: an isothermal compression stage, an isothermal heat release stage, an isothermal expansion stage, and an isothermal heat absorption stage. As shown in Figure 6, in the isothermal compression stage of the Stirling engine 10, the second piston 60 moves toward the first heat exchanger 120 to an equilibrium position, and the venting mechanism located on the first piston 140 is in a closed state. As shown in Figure 7, in the isothermal heat release stage of the Stirling engine 10, the second piston 60 continues to move from the equilibrium position toward the first heat exchanger 120. Furthermore, the venting mechanism 150 located on the first piston 140 is in the intake state; as shown in Figure 8, during the isothermal expansion stage of the Stirling engine 10, the first piston 140 moves away from the second heat exchanger 130 to its limit position, and the venting mechanism 150 located on the first piston 140 is in the closed state; as shown in Figure 9, during the isobaric heat absorption stage of the Stirling engine 10, the second piston 60 moves away from the first heat exchanger 120 from its equilibrium position, the first piston 140 moves toward the second heat exchanger 130, and the venting mechanism 150 located on the first piston 140 is in the exhaust state.

[0076] Within one alternating cycle, the Stirling heat engine 10 operates sequentially in the isothermal compression stage, the isobaric heat release stage, the isothermal expansion stage, and the isobaric heat absorption stage. ① Isothermal compression stage, hot end (second end) releases heat: the compression piston (second piston 60) moves to the equilibrium position, the system pressure P1 = Pin0, and the venting mechanism 150 of the expansion piston (first piston 140) is closed; ② Isothermal heat release stage, hot end releases heat, regenerator 160 stores heat: the compression piston continues to move to the right, the system pressure P2 = Pin0 + ΔP, the venting mechanism 150 of the expansion piston takes in air, and the compression piston moves isothermally to the rightmost side; ③ Isothermal expansion stage, cold end absorbs heat: the expansion piston moves to the right, the system pressure P3 > Pout0, the venting mechanism 150 of the expansion piston is closed, and the expansion piston moves to the rightmost side; ④ Isothermal heat absorption stage, cold end absorbs heat, regenerator 160 releases heat: the compression piston and expansion piston reset to the left, the system pressure P4 = Pout0 - ΔP, the venting mechanism 150 of the expansion piston exhausts air, and the compression piston and expansion piston move to the leftmost side.

[0077] In the four operating stages described above, the theoretical changes in pressure P and volume V within the first pressure chamber A1 and the second pressure chamber A2 are shown in Figure 10, forming two isothermal and two isochoric theoretical Stirling cycles. The theoretical cycle efficiency of this cycle is 100%, equivalent to the Carnot cycle efficiency. Since the heat exchange process in the heat exchanger is non-ideal isothermal, the actual pressure-volume changes in the above operating stages are shown in Figure 12. The actual cycle efficiency can be improved by at least 21.7% compared to the cycle efficiency of a conventional vapor compression cycle (as shown in Figure 12; Figures 11 and 12 use the same coordinate system and scale).

[0078] This application further proposes a heat pump system, including a Stirling engine 10 and a drive mechanism, the drive mechanism driving a first piston 140 to move.

[0079] In some embodiments, the drive mechanism may be a compressor, including a rotary compressor. Rotary compressors have advantages such as high mechanical efficiency and energy saving, thus improving the efficiency of the heat pump system.

[0080] In some embodiments, the rotary compressor may be a rotary compressor such as a rotor, scroll, or centrifugal compressor, which has a higher mechanical efficiency than a traditional reciprocating piston compressor.

[0081] For information on the structure and principle of the Stirling engine 10, please refer to the above embodiments.

[0082] The Stirling engine provided in this application includes at least a first heat exchanger, a second heat exchanger, a regenerator, and a first piston disposed within a housing cavity formed by the shell. The first piston is disposed within a first end and located at the end of the first heat exchanger opposite to the regenerator. The outer edge of the first piston is sealed to the inner wall of the first end, and a first pressure chamber is formed between the first piston and the first heat exchanger. The first piston is provided with a first buffer chamber, and a venting mechanism is provided on the side of the first piston facing the first heat exchanger, which is connected to the first buffer chamber and the first pressure chamber respectively, for adjusting the air pressure in the first pressure chamber through the venting mechanism and the first buffer chamber. In this way, on the one hand, this application utilizes the first buffer chamber formed within the first piston as a working fluid buffer space for the first pressure chamber. Combined with the venting mechanism, the gas pressure within the first pressure chamber can be adjusted, thus enabling alternating motion of the working fluid between the first and second ends of the chamber. This creates a temperature gradient in the regenerator, achieving heat pumping from the low-temperature end to the high-temperature end. On the other hand, through improvements to the piston structure, this application allows for the adjustment of the gas pressure within the first pressure chamber via the venting mechanism and the first buffer chamber within the first piston. Compared to existing methods that rely solely on the axial reciprocating motion of the piston relative to the piston cylinder to adjust the gas pressure, this application's venting mechanism offers higher operational efficiency, improving the mechanical efficiency of the Stirling engine. Furthermore, the first buffer chamber, as a buffer space for the first pressure chamber, allows for faster and more precise adjustment of the system's pressure and velocity waves. It also addresses the problem of inefficient work done by the piston during working fluid compression and expansion due to inertial forces, optimizing the working fluid circulation pattern. Therefore, this application can improve the heat pumping efficiency and energy efficiency of the Stirling engine.

[0083] Furthermore, the Stirling engine of this application features an optimized design of the piston inlet / outlet ports / valve and hollow volume, resulting in an optimal circulation pattern. This design is simple in structure, has few adjustable parts, simplifies control, and achieves higher system energy efficiency than traditional Stirling cycles. The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

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