Piston and compressor

Abstract

The present application relates to the field of compressor, specifically relates to a piston and compressor;Piston includes: piston main body, axial first end is formed with pressurizing end face, pressurizing end face is used for pressurizing the fluid in the compression chamber;The pressurizing end face is provided with sliding hole, and the sliding hole is provided with sliding rod;The first end of the sliding rod can gradually extend into the compression chamber as the temperature in the compression chamber rises to solve the technical problem that the volumetric efficiency decreases caused by the increase of the pressure ratio of the piston compressor working frequency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of compressors, in particular to a piston and a compressor. BACKGROUND

[0002] For reciprocating piston compressors, the pump head assembly of the cylinder includes, in addition to the valve assembly of the suction valve and the discharge valve, a cylinder cover that presses and fixes the valve assembly on the cylinder base, which completely covers the valve assembly to form a closed cavity. When the piston reciprocates inside the cylinder, it compresses the gas or refrigerant and then discharges it from the cylinder through the discharge hole and the discharge valve into the cavity surrounded by the cylinder cover. The compressed refrigerant is then transported to the outside of the compressor through the internal discharge coil and finally enters the refrigeration cycle system of the refrigerator. To prevent the piston from being damaged by collision with the valve assembly during the operation of the piston to the top dead center, (when the piston connected to one end of the connecting rod generates a large centrifugal force, and the crankshaft connected to the other end of the connecting rod also generates a large deformation, which further aggravates the problem of collision), and to avoid the impact noise caused by the collision of the compressor with the valve assembly, which affects the user experience, a certain gap is usually left between the front end face of the piston and the valve assembly when the piston of the conventional piston compressor is at the top dead center. The main factors affecting the volumetric efficiency λ are the volume coefficient λ V , the pressure coefficient λ P , the temperature coefficient λ T , and the leakage coefficient λ l , i.e. λ = λ V λ P λ T λ l , where the volume coefficient λ V mainly reflects the influence of the clearance volume and the compression ratio on the volumetric efficiency, and can be expressed as λ V = 1 - c (ε 1 / m - 1), where c is the clearance volume, ε is the compression ratio, and m is a variable index. It can be seen that as the clearance volume and the compression ratio increase, λ V decreases, especially in low-temperature refrigeration conditions, i.e. the influence of the compression ratio on λ V is dominant, and the volume coefficient is very low at this time. Therefore, the larger the gap, the smaller the volume coefficient, and the lower the volumetric efficiency, especially in high-compression-ratio conditions, the decrease in volumetric efficiency will be more obvious.

[0003] For energy saving considerations, the variable displacement adjustment technology of small piston compressors also has some patents that propose some technical means, such as the patent CN 110469497 A "Compressor and refrigeration equipment with same" of Gree Electric Appliances, the patents CN214787931 U "Effective cylinder volume for refrigeration compressor", CN 215256727 U "Electromagnetic variable displacement device for compressor cylinder", CN 214787934 U "Variable displacement device for adjusting effective cylinder volume of compressor" and CN112012918 A "Piston refrigeration compressor variable displacement structure" of Gaskinella, all of which are to add a slide valve structure or a rotary valve structure capable of adjusting the size of the cylinder volume to the side of the cylinder block in the direction of piston movement or the cylinder head at the front end in the direction of piston movement. The position of the slide valve structure can be adjusted by using different pressure gases in the cylinder head under different working conditions, or the position of the slide valve structure can be adjusted by an electromagnetic structure, and the rotary valve structure can be controlled by a micro motor.

[0004] However, these structures are all improved on the basis of a certain distance between the piston and the valve assembly at the top dead center of the original piston compressor, but the cavity added with these slide valve structures will increase the clearance volume of the compressor on the original basis, the volume coefficient of the compressor will be smaller, and the volumetric efficiency will be lower.

[0005] At present, there is no good solution to the above technical problems. SUMMARY

[0006] To solve the technical problem of volumetric efficiency reduction caused by the increase of working frequency and pressure ratio of the piston compressor, a piston and a compressor are proposed.

[0007] In one aspect, the present application proposes a piston for a piston compressor, wherein the piston compressor forms a compression chamber, comprising:

[0008] a piston body, an axial first end of which forms a pressurizing end face, the pressurizing end face being used for pressurizing fluid in the compression chamber;

[0009] a sliding hole is arranged on the pressurizing end face, and a sliding rod is arranged in the sliding hole; a first end of the sliding rod can gradually extend into the compression chamber as the temperature in the compression chamber increases.

[0010] Preferably, the sliding rod gradually retracts into the sliding hole as the temperature in the compression chamber decreases.

[0011] Preferably, a thermal response spring is arranged in the sliding hole, a first end of the thermal response spring is fixedly connected with the sliding rod, and a second end of the thermal response spring is fixedly connected with an inner wall surface of the sliding hole.

[0012] The length of the thermal responsive spring can be increased with the temperature rise in the compression cavity to push the first end of the slide rod into the compression cavity.

[0013] The slide hole is further provided with an elastic member, and the thermal responsive spring can be compressed by the elastic member.

[0014] Preferably, the slide hole is provided with a thermal responsive spring, the first end of the thermal responsive spring is connected with the slide rod, and the second end of the thermal responsive spring is connected with the inner wall of the slide hole.

[0015] The length of the thermal responsive spring can be increased with the temperature rise in the compression cavity to push the first end of the slide rod into the compression cavity, and the length of the thermal responsive spring can be shortened with the temperature drop in the compression cavity to pull the first end of the slide rod to slide towards the direction away from the compression cavity.

[0016] Preferably, the slide hole is a through hole penetrating through the axial two ends of the piston, and the end of the slide hole away from the compression cavity is sealed by a screw; when the slide rod is arranged in the slide hole, a first interval is formed between the screw and the end of the slide rod away from the compression cavity, and the thermal responsive spring is arranged in the first interval.

[0017] Preferably, the end of the first end of the slide rod is provided with a buffer part.

[0018] Preferably, the inner wall of the slide hole comprises a first step surface away from the compression cavity.

[0019] The second end of the slide rod is provided with a rod head, the rod head is formed with a second step surface towards the first end of the slide rod; when the slide rod is inserted into the slide hole, a second interval is formed between the first step surface and the second step surface, the elastic member is a mechanical spring, and the mechanical spring is arranged in the second interval and sleeved on the slide rod.

[0020] Preferably, the slide rod comprises a first rod segment and a second rod segment, the cross-sectional area of the first rod segment is greater than that of the second rod segment, and the slide rod is fixedly connected with the rod head through the second rod segment.

[0021] Preferably, the rod head is provided with a protrusion protruding away from the slide rod.

[0022] Preferably, the first rod segment is sealed and slides with the slide hole.

[0023] In another aspect, the application further provides a compressor comprising the piston.

[0024] The application sets the slide bar on the piston, so that the slide bar can slide towards or away from the compression cavity to change the clearance volume included by the compression cavity, with the increase of the compressor working frequency, the temperature in the compression cavity increases accordingly, the longer the length of the slide bar extending into the compression cavity, the smaller the compression cavity and the clearance volume, thereby reducing the adverse effects caused by the increase of the pressure ratio due to the temperature rise, improving the working efficiency of the compressor, compared with other settings of electromagnetic structure to adjust the compression cavity volume to increase the clearance volume, the disclosed mode reduces the clearance volume while adjusting the size of the compression cavity, thereby improving the operating efficiency of the compressor. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is an exploded view of the pump body assembly of the compressor of the embodiment of the application;

[0026] Figure 2 It is a sectional view of the pump body assembly of the embodiment of the application;

[0027] Figure 3 It is an exploded view of the piston and accessories of the embodiment of the application;

[0028] Figure 4 It is an oblique view of the piston of the embodiment of the application;

[0029] Figure 5 It is a sectional view of the piston of the embodiment of the application;

[0030] Figure 6 It is an exploded view of the thermal induction slide bar assembly of the embodiment of the application;

[0031] Figure 7 It is a schematic view of the relationship between the slide bar and the rod head of the embodiment of the application;

[0032] Figure 8 It is a schematic view of the slide bar on the piston under low-frequency operation of the embodiment of the application;

[0033] Figure 9 It is a schematic view of the slide bar on the piston under medium-frequency operation of the embodiment of the application;

[0034] Figure 10 It is a schematic view of the slide bar on the piston under high-frequency operation of the embodiment of the application;

[0035] Figure 11 It is an embodiment of the application Figure 10 Enlarged view at K;

[0036] Figure 12 It is an embodiment of the application Figure 10 Schematic view when the thermal induction spring and the mechanical spring are removed at K;

[0037] Figure 13Actual operating pressure-volume (P-V) diagram of the piston compressor of the embodiment of the present application;

[0038] Reference signs are indicated as:

[0039] 10, cylinder block; 20, plain rolling bearing; 30, crankshaft assembly; 40, piston assembly; 41, piston body; 41a, outer cylindrical surface; 41b, cutout groove; 41c, inner hole; 41d, upper limiting rib; 41e, lower limiting rib; 41h, sliding hole; 41h-1, large round hole; 41h-2, small round hole; 41h-3, first step surface; 41f, large pin hole; 41g, small pin hole; 42, connecting rod; 43, piston pin; 44, circlip pin; 45, thermal induction sliding rod assembly; 45a, sliding rod; 45a-1, first rod segment; 45a-2, second rod segment; 45b, mechanical spring; 45c, rod head; 45c-1, abutment, 45c-2, protrusion; 45c-3, groove; 45c-4, second step surface; 45d, thermal induction spring; 46, screw; 50, valve assembly; 51, suction valve gasket; 52, suction valve plate; 53, valve plate; 54, exhaust valve plate; 55, exhaust valve limiting plate; 56, V-shaped circlip; 60, cylinder head; 70, suction muffler assembly; 2, compression chamber; 3, pressurized end face; 101, first interval; 102, second interval. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0041] The terms used in the embodiments of the present application are merely for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Plural" generally includes at least two, but does not exclude the case of including at least one.

[0042] It should be understood that the term "and / or" as used herein merely describes an associated relationship, that is, there can be three relationships, for example, A and / or B, which can represent three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects; "first", "second" in the text are only to distinguish different technical features, and not have a sequence; "upper", "lower", "front", "rear" in the text are only to make the position relationship of the technical features more convenient to explain, and have certain significance only in combination with the actual use situation or the specific position description in the preceding text, and not an absolute position relationship.

[0043] It should also be noted that the terms "comprise", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the goods or system comprising a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such goods or system. Without more limitation, the element defined by the sentence "comprising a" does not exclude the existence of another identical element in the goods or system comprising the element.

[0044] The present application relates to the field of compressors, in particular to a piston and a compressor.

[0045] For a reciprocating piston compressor, the pump head assembly of its cylinder includes, in addition to the valve assembly of the suction valve and the exhaust valve, a cylinder cover that presses and fixes the valve assembly on the cylinder base. The cylinder cover completely covers the valve assembly to form a closed cavity. When the piston reciprocates inside the cylinder, it compresses the gas or refrigerant and then discharges it from the exhaust hole and exhaust valve into the cavity surrounded by the cylinder cover. The compressed refrigerant is then transported to the outside of the compressor through the internal exhaust coil and finally enters the refrigeration cycle system of the refrigerator. To prevent the piston from being damaged by collision with the valve assembly during the operation of the piston to the top dead center, (when operating at high speed, the piston connected to one end of the connecting rod will generate a large centrifugal force, and the crankshaft connected to the other end of the connecting rod will also generate a large deformation, which will make the problem of collision even worse), and to avoid the impact noise caused by the collision of the compressor with the valve assembly, which will affect the user's experience, a certain gap is usually left between the front end face of the piston and the valve assembly when the piston of the conventional piston compressor is at the top dead center. The main factors affecting the volumetric efficiency λ are the volumetric coefficient λ V , the pressure coefficient λ P , the temperature coefficient λ T , and the leakage coefficient λ l , that is, λ = λ V λ P λ T λl wherein, volume coefficient λ V mainly reflects the size of the influence of the clearance volume and compression ratio on the volumetric efficiency, which can be expressed as λ V = 1-c(ε 1 / m -1), where c is the clearance volume, ε is the compression ratio, and m is the polytropic index. It can be seen that as the clearance volume and compression ratio increase, λ V decreases, especially in the low-temperature refrigeration working condition, that is, the influence of the compression ratio on λ V is dominant, at which time the volume coefficient is very low. Therefore, the larger the reserved gap, the smaller the volume coefficient, and the lower the volumetric efficiency, especially in the high compression ratio working condition, the decrease in volumetric efficiency will be more obvious.

[0046] For energy saving considerations, some patents have proposed some technical means for variable displacement adjustment technology of small piston compressors, such as the patent CN 110469497 A “Compressor and Refrigeration Equipment Having the Same” of Gree Electric Appliances, the patents CN 214787931 U “Effective Cylinder Volume for Refrigeration Compressor”, CN 215256727 U “Electromagnetic Variable Displacement Device for Cylinder of Compressor”, CN 214787934 U “Variable Displacement Device for Adjusting Effective Cylinder Volume of Compressor” and CN 112012918 A “Variable Displacement Structure of Piston Refrigeration Compressor” of Gaskin Bell. These patents all add a slide valve structure or a rotary valve structure capable of adjusting the size of the cylinder volume to the side of the cylinder base in the direction of piston movement or the cylinder cover at the front end in the direction of piston movement. The position of the slide valve structure can be adjusted by using different pressure gases in the cylinder cover under different working conditions, or the position of the slide valve structure can be adjusted by an electromagnetic structure, and the rotary valve structure can be controlled by a micro motor.

[0047] However, these structures are all improved on the basis of a certain distance between the piston and the valve assembly at the top dead center of the original piston compressor, but the cavity of the added slide valve structure will increase the clearance volume of the compressor on the original basis, the volume coefficient of the compressor will be smaller, and the volumetric efficiency will be lower.

[0048] To solve the technical problem of the decrease in volumetric efficiency caused by the increase in working frequency and compression ratio of the piston compressor, the present application provides a piston, as shown in Figures 1-13 Fig. 1, for a piston compressor, the piston compressor is formed with a compression chamber 2, comprising: a piston body 41, an axially first end of which is formed with a pressurizing end face 3, the pressurizing end face 3 being used for pressurizing the fluid in the compression chamber 2; a sliding hole 41h is arranged on the pressurizing end face 3, and a slide rod 45a is arranged in the sliding hole 41h; the first end of the slide rod 45a can gradually extend into the compression chamber 2 as the temperature in the compression chamber 2 increases.

[0049] The compression chamber 2 includes a clearance volume, and the slide rod 45a enters the clearance volume when the slide rod 45a extends into the compression chamber 2; the slide rod 45a extending into the clearance volume reduces the size of the clearance volume, thereby at least partially reducing the adverse effects of the increase in compression ratio on the compressor. The piston compressor is provided with a cylinder hole, and the piston sliding in the cylinder hole performs compression work on the compression chamber 2 of the compressor; when the compressor operates at a low frequency and a low speed, the heat generated by mechanical friction is small, the temperature of the compressed gas or refrigerant is low, and the first end of the slide rod 45a does not or rarely extends into the compression chamber 2; when the first end of the slide rod 45a does not extend into the compression chamber 2, the end face of the first end of the slide rod 45a is flush with the end face of the first end of the piston, thereby avoiding an increase in the clearance volume. When the operating frequency of the compressor increases, the operating speed of the piston also increases accordingly, the heat generated by mechanical friction is large, the temperature of the compressed gas or refrigerant is high, and the length of the first end of the slide rod 45a extending into the clearance volume is large, thereby reducing the clearance volume. When the compressor operates at the highest frequency and the highest speed, the heat generated by mechanical friction is the largest, the temperature of the compressed gas or refrigerant reaches the highest, the length of the first end of the slide rod 45a extending into the compression chamber 2 also reaches the longest, and the clearance volume reaches the smallest; and the slide rod 45a gradually retracts into the sliding hole 41h as the temperature in the compression chamber 2 decreases.

[0050] That is, the size of the clearance volume decreases as the temperature increases, and the size of the compression chamber 2 also decreases as the temperature increases; the volumetric efficiency of the piston compressor is λ = λ V × λ P × λ T × λ l . Wherein, the volumetric coefficient λ V reflects the influence of the clearance volume and the compression ratio on the volumetric efficiency, and is expressed as λ V = 1-c(ε 1 / m -1), c is the clearance volume, ε is the compression ratio, and m is a variable index. It can be seen that λ V decreases as the clearance volume and the compression ratio increase, and in particular, at a high-pressure ratio operating condition of low-temperature refrigeration, the volumetric coefficient λ V is low, and at this time, the influence of the compression ratio on λ V begins to dominate. Therefore, in the case where the temperature in the compression chamber 2 increases to cause an increase in the compression ratio, the slide rod 45a extending into the clearance volume reduces the size of the clearance volume, thereby at least partially reducing the adverse effects of the increase in compression ratio on the compressor.

[0051] As the working frequency of the compressor is higher, the temperature in the compression chamber 2 is higher, and when the suction pressure is constant, the exhaust pressure is greater, and the corresponding pressure ratio (the ratio of the absolute exhaust pressure to the absolute suction pressure) is greater, and the greater the pressure ratio, the greater the pressure required by the compressor to compress the gas or refrigerant in the compression chamber 2, so that the power consumption of the compressor is large, and the performance of the compressor is reduced; the reduction of the clearance volume can reduce the adverse effects of the increase of the pressure ratio on the compressor. The volumetric efficiency of the compressor under low frequency working condition is not only not affected, but also the volumetric efficiency under high compression ratio working condition such as medium and high frequency is not reduced.

[0052] The second end of the piston is provided with an inner hole 41c of the piston, one end of the connecting rod 42 slidingly driving the piston is arranged in the inner hole 41c of the piston, and the inner hole 41c of the piston is provided with an upper limiting rib 41d and a lower limiting rib 41e for limiting the connecting rod 42; the sliding hole 41h is arranged on the plane of the upper limiting rib 41d and the lower limiting rib 41e about the piston axis; due to the structural limitation of the piston, the number of sliding holes 41h is generally even and arranged symmetrically about the piston axis.

[0053] When the working frequency of the compressor is reduced, the temperature in the compression chamber 2 is reduced, the pressure ratio is reduced, the slide rod 45a slides into the sliding hole 41h, the clearance volume is increased, and the larger compression chamber 2 can suck more gas for compression, thereby improving the compression efficiency.

[0054] Preferably, as shown in Figures 6-12 The first end of the thermal sensitive spring 45d is fixedly connected with the slide rod 45a, and the second end of the thermal sensitive spring 45d is fixedly connected with the inner wall surface of the sliding hole 41h; the length of the thermal sensitive spring 45d can be increased with the increase of the temperature in the compression chamber 2 to push the first end of the slide rod 45a into the compression chamber 2.

[0055] The elastic member is compressed when the thermal responsive spring 45d is elongated. The elastic member can be a mechanical spring 45b made of spring steel; the thermal responsive spring 45d is made of one-way memory alloy, which is binary memory alloy or ternary memory alloy; the binary memory alloy or ternary memory alloy is Ni-Ti system or Cu-based system or Fe-based system, and the austenite temperature line Ac of the memory alloy is within the operating temperature range of the compressor, which is generally room temperature to 200°C. When the temperature in the compression chamber 2 is higher than the temperature line Ac, the memory alloy gradually changes from martensite phase to austenite phase, at which time the thermal responsive spring 45d is elongated and the mechanical spring 45b is compressed to store elastic potential energy. When the ambient temperature decreases, the thermal responsive spring 45d cannot be automatically shortened, at which time the compressed mechanical spring 45b releases the elastic potential energy and the slide rod 45a slides into the sliding hole 41h, and at the same time the slide rod 45a shortens the thermal responsive spring 45d. The one-way memory alloy is low in price and the mechanical spring reacts quickly. By using the thermal responsive spring 45d and the mechanical spring 45b, on the one hand, the thermal responsive spring 45d is made of one-way memory alloy, which reduces the cost; on the other hand, the mechanical spring 45b deforms more quickly, which can accelerate the movement of the slide rod 45a.

[0056] Preferably, the sliding hole 41h is provided with a thermal responsive spring 45d, the first end of the thermal responsive spring 45d is connected with the slide rod 45a, and the second end of the thermal responsive spring 45d is connected with the inner wall surface of the sliding hole 41h; the length of the thermal responsive spring 45d can increase with the increase of the temperature in the compression chamber 2 to push the first end of the slide rod 45a into the compression chamber 2; the length of the thermal responsive spring 45d can decrease with the decrease of the temperature in the compression chamber 2 to pull the first end of the slide rod 45a to slide toward the direction away from the compression chamber 2. The thermal responsive spring 45d is made of two-way memory alloy, the thermal responsive spring 45d is elongated when the ambient temperature increases, and the thermal responsive spring 45d is shortened when the ambient temperature decreases; the two-way memory alloy can cancel the mechanical spring, simplify the structure, and improve the production efficiency.

[0057] Preferably, as shown in Figures 11-12 the sliding hole 41h is a through hole penetrating through the axial two ends of the piston, and the end of the sliding hole 41h away from the compression chamber 2 is sealed by a screw 46; when the slide rod 45a is arranged in the sliding hole 41h, the screw 46 and the end of the slide rod 45a away from the compression chamber 2 form a first interval 101, and the thermal responsive spring 45d is arranged in the first interval 101.

[0058] The thermal sensitive spring 45d is arranged in the first interval 101 and is elongated or shortened with the temperature change in the compression chamber 2. Since the first interval 101 is arranged at the end of the slide rod 45a, on one hand, the thermal sensitive spring 45d is arranged at the axial end to enable the slide rod to have a buffering effect when colliding with the valve assembly in the compression chamber 2, preventing the slide rod 45a from being bent and unable to retract into the slide hole 41h; on the other hand, the cross-sectional area of the slide rod 45a can be as large as possible within the allowable range. When the first end of the slide rod 45a extends into the compression chamber 2 by a certain length, the larger the cross-sectional area, the larger the size range of the adjustable clearance volume, and the further reduction of the adverse effects of pressure ratio rise on the compressor.

[0059] Preferably, the end of the first end of the slide rod 45a is provided with a buffer portion.

[0060] The buffer portion can be formed by coating a polymer layer on the end of the first end of the slide rod 45a, such as coating polytetrafluoroethylene; the buffer portion can effectively avoid the impact noise and vibration caused by the slide rod 45a colliding with the valve assembly under accidental circumstances (the slide rod 45a has a tendency to move forward due to inertial force when the piston runs to the top dead center direction). The screw 46 is an internal countersunk screw 46, and to ensure sealing, sealing glue or adhesive can be applied to the threaded portion of the screw 46.

[0061] Preferably, as shown in Figures 6-7 the inner wall surface of the slide hole 41h includes a first step surface 41h-3 facing away from the compression chamber 2; the second end of the slide rod 45a is provided with a rod head 45c, and the rod head 45c is formed with a second step surface 45c-4 facing the first end of the slide rod 45a; when the slide rod 45a is inserted into the slide hole 41h, a second interval 102 is formed between the first step surface 41h-3 and the second step surface 45c-4, and the elastic member is a mechanical spring 45b arranged in the second interval 102 and sleeved on the slide rod 45a.

[0062] The rod head 45c has a guiding effect on the sliding rod 45a in the sliding hole 41h, avoiding the sliding rod 45a from being stuck in the sliding hole 41h. Meanwhile, the first step surface 41h-3 formed by the rod head 45c has a limiting effect on the mechanical spring 45b, facilitating the mechanical spring 45b to work on the sliding rod 45a. The mechanical spring 45b is arranged in the second interval 102 and sleeved on the sliding rod 45a, and the two ends of the mechanical spring 45b are respectively in abutment with the first step surface 41h-3 and the second step surface 45c-4. The mechanical spring 45b is sleeved on the sliding rod 45a, which can reduce the cross-sectional area of the sliding hole 41h, reduce the occupation of the piston body by the sliding hole 41h, and ensure the rigidity of the piston. At the same time of ensuring the rigidity of the piston, the cross-sectional area of the sliding rod 45a can be as large as possible. When the first end of the sliding rod 45a extends into the compression chamber 2 by a certain length, the larger the cross-sectional area is, the larger the size range of the adjustable clearance volume is, and the adverse effect of the pressure ratio increase on the compressor is further reduced.

[0063] The rod head 45c can be provided with a groove 45c-3, and one end of the sliding rod 45a is inserted into the groove 45c-3 in an interference fit. In the radial direction of the sliding rod 45a, the cross-sectional area of the sliding rod 45a4 is smaller than that of the rod head 45c. In actual processing, the sliding rod 45a4 and the rod head 45c are processed respectively, which can reduce material consumption and reduce costs.

[0064] Preferably, as shown in Figure 7 The sliding rod 45a includes a first rod segment 45a-1 and a second rod segment 45a-2, and the cross-sectional area of the first rod segment 45a-1 is larger than that of the second rod segment 45a-2. The sliding rod is fixedly connected with the rod head 45c through the second rod segment 45a-2.

[0065] The cross-sectional area of the first rod segment 45a-1 is larger than that of the second rod segment 45a-2, which can reduce the weight of the sliding rod 45a and improve the sliding sensitivity of the sliding rod 45a under the action of the thermal induction spring 45d and the mechanical spring 45b while ensuring the effective adjustment of the sliding rod 45a on the clearance volume.

[0066] Preferably, as shown in Figure 7 The rod head 45c is provided with a protrusion 45c-2 protruding away from the sliding rod 45a4.

[0067] When the thermal sensitive spring 45d is arranged in the first interval 101, one end of the thermal sensitive spring 45d is sleeved on the protrusion 45c-2, the protrusion 45c-2 forms a radial positioning effect on the thermal sensitive spring 45d, avoids the thermal sensitive spring 45d from shaking in the first interval 101, and improves the stability of the movement of the slide rod 45a driven by the thermal sensitive spring 45d. The length of the protrusion 45c-2 can be prolonged, and the length of the screw 46 is adjusted to be screwed in, when the protrusion 45-c is in contact with the screw 46, the mechanical spring 45b has a certain elastic force to make the protrusion 45-c keep in contact with the screw 46, at this time, the end surface of the first end of the slide rod 45a is flush with the pressurizing end surface 3 of the piston.

[0068] Preferably, the first rod segment 45a-1 and the slide hole 41h are sealed from sliding.

[0069] The first rod segment 45a-1 and the slide hole 41h are sealed from sliding, the inside of the slide hole 41h is avoided from being communicated with the compression cavity 2, and then the increase of the residual space volume caused by the setting of the slide hole 41h is avoided, which is beneficial to improve the performance of the compressor.

[0070] The application further provides a compressor comprising the above piston.

[0071] As Figures 1-13As shown, the compressor's pump body assembly includes a cylinder block 10, a flat rolling bearing 20, a crankshaft assembly 30, a piston assembly 40, a valve assembly 50, a cylinder head 60, and an intake muffler assembly 70. The crankshaft assembly 30 is placed within the shaft bore of the cylinder block 10. A flat rolling bearing 20 is positioned between the crankshaft assembly 30 and the cylinder block to prevent wear between the bearing housing of the cylinder block 10 and the crankshaft assembly 30, thus converting sliding friction into rolling friction and reducing frictional power consumption. The piston body 41 of the piston assembly 40 and the small shaft hole of the connecting rod 42 are connected together by the piston pin 43. The piston pin 43 is installed in the through hole large pin hole 41f, and the piston pin 43 is limited and fixed on the piston body 41 by the snap ring pin 44. The snap ring pin 44 is installed in the blind hole small pin hole 41g, and the large shaft hole of the connecting rod 42 is connected to the eccentric crank part of the crankshaft assembly 30. The motor drives the crankshaft assembly 30 to drive the piston assembly 40 to perform reciprocating linear motion in the compression chamber of the cylinder seat 10 to compress the intake gas or refrigerant and do work. Valve assembly 50 includes intake and exhaust valve gaskets 51, intake valve plate 52, valve plate 53, exhaust valve plate 54, exhaust valve limiting plate 55, and V-ring 56. The fixed cylinder head 60 not only compresses the valve assembly 50 to form a sealed cavity in the compression chamber of the cylinder seat 10, but also compresses the exhaust valve limiting plate 50 and V-ring 56 of the valve assembly 50, thereby limiting the lift of the exhaust valve plate 54. The intake and exhaust valve gaskets 51 are respectively placed between the cylinder seat 10 and the intake valve plate 52, and between the valve plate 53 and the cylinder head 60, thereby enhancing the sealing performance between the valve assembly 50 and the cylinder seat, and between the valve assembly 50 and the cylinder head 60. An intake muffler assembly 70 is added to the intake front end of the valve assembly 50. This intake muffler assembly 70 can reduce the airflow pulsation noise generated by the gas or refrigerant drawn into the compression chamber from the intake port. Figure 4 As shown, a notch 41b is provided on the outer cylindrical surface 41a of the piston body 41 in the piston assembly 40 to store lubricating oil and reduce the contact area between the piston body 41 and the cylinder wall of the cylinder seat 10, thereby reducing frictional power consumption. An upper limit rib 41d and a lower limit rib 41e are provided in the inner hole 41c of the piston body 41, which not only strengthens the overall strength of the piston body 41 but also facilitates the provision of small pin holes 41g and sliding holes on these two limit ribs. A through-hole large pin hole 41f is provided on the outer cylindrical surface 41a of the piston body 41, into which a piston pin 43 can be inserted, thus forming a rotatable hinge structure between the piston body 41 and the connecting rod 42. A blind small pin hole 41g is provided on the plane of the upper limit rib 41d, into which a snap ring pin 44 is inserted to prevent the piston pin 43 from moving freely within the large pin hole 41f.

[0072] The following describes the working process of the compressor at different operating frequencies.

[0073] like Figure 6As shown, the slide rod 45a, mechanical spring 45b, rod head 45c, and thermal spring 45d together constitute the thermal sliding rod assembly 45. The thermal sliding rod assembly 45 is fixed and limited within the sliding hole 41h by an internal countersunk screw 46. The sliding hole includes a large circular hole 41h-1 and a small circular hole 41h-2, which are connected by a first stepped surface.

[0074] like Figure 7 As shown, one end of the slide rod 45a is the first rod segment 45a-1, and the other end is the small second rod segment 45a-2. One end of the rod head 45c is the base 45c-1, and the other end is the protrusion 45c-2. A groove 45c-3 is formed on the plane of the base 45c-1, and the rod head 45c can slide within the axial direction of the sliding hole 41h. Then, the second rod segment 45a-2 of the slide rod 45a is press-fitted into the groove 45c-3 of the base 45c-1 of the rod head 45c.

[0075] like Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the assembly sequence of the heat-sensitive slide rod assembly 45 is as follows: first, a mechanical spring 45b is installed at the end of the assembly consisting of the already clamped slide rod 45a and the rod head 45c facing the slide rod 45a; then, the assembly consisting of the already clamped slide rod 45a, the rod head 45c, and the mechanical spring 45b is assembled into the sliding hole 41h; next, the heat-sensitive spring 45d is also installed into the sliding hole 41h; and finally, the countersunk screw 46 is assembled and fixed at the tail end in the sliding hole 41h.

[0076] In this assembly, the first segment 45a-1 of the slide rod 45a of the thermally sensitive slide rod assembly 45 is inserted into the small round hole 41h-2 at the front end of the sliding hole 41h of the piston body 41. One end of the mechanical spring 45b abuts against the plane of the base 45c-1 of the rod head 45c, and the other end of the mechanical spring 45b abuts against the first step surface 41h-3 between the large round hole 41h-1 and the small round hole 41h-2 of the sliding hole 41h. One end of the thermally sensitive spring 45d abuts against the large base surface of the rod head 45c where the protrusion 45c-2 is provided, and the other end of the thermally sensitive spring 45d abuts against the plane of the countersunk screw 46.

[0077] Furthermore, to prevent the sealing performance of the piston body 41 from being adversely affected after the heat-sensitive slide rod assembly 45 is installed, adhesive is applied before the countersunk screw 46 is assembled and fixed into the sliding hole 41h.

[0078] The base material of the thermal induction spring is a shape memory alloy, while the mechanical spring is made of spring steel. The shape memory alloy also exhibits shape memory effect (SME) and superelasticity (SE).

[0079] Furthermore, the shape memory alloy is either a binary or ternary shape memory alloy, and the binary or ternary shape memory alloy is either Ni-Ti based, Cu-based, or Fe-based. The austenite temperature line Ac of the selected shape memory alloy falls within the operating temperature range of the compressor, which is approximately room temperature to 200°C. When the temperature inside the compressor is higher than this austenite temperature line Ac, the shape memory alloy gradually transforms from martensite to austenite; when the temperature inside the compressor is lower than this austenite temperature line Ac, the shape memory alloy gradually transforms from austenite to martensite, thereby achieving the purpose of causing the thermally induced spring to deform, elongate, and contract.

[0080] like Figure 8 As shown, when the compressor operates under low-frequency and low-speed conditions, the temperature generated by the compressed gas or refrigerant and the temperature generated by mechanical friction are relatively low. This temperature does not reach the austenitic temperature line Ac of the shape memory alloy base material of the thermal induction spring 45b. At this time, the mechanical spring 45b is in a compressed state, and the thermal induction spring 45d is in an extended state. Consequently, the end face 45a-3 of the first segment of the slide rod 45a is flush with the end face of the first end of the piston body 41. That is, the first segment 45a-1 of the slide rod 45a is still completely inside the small circular hole 41h-2 of the sliding hole 41h of the piston body 41. At this time, the volume of the compressor inside the compressor is V1. The actual pressure-volume (PV) of the piston compressor during operation is as follows: Figure 13 As shown, the intake process is curve 4-1, the compression process is curve 1-2, the exhaust process is curve 2-3, and the expansion process is curve 3-4. That is, the PV change of the piston compressor at this time is a closed loop curve 4-1-2-3 that repeats repeatedly.

[0081] like Figure 9 As shown, when the compressor operates under medium-frequency and medium-speed conditions, the temperature generated by the compressed gas or refrigerant and the temperature generated by mechanical friction gradually increase. This temperature is slightly higher than the austenitic temperature line Ac of the shape memory alloy base material of the thermal induction spring 45d. At this time, the thermal induction spring 45d gradually elongates, and the mechanical spring 45b gradually contracts, causing the slide rod 45a to gradually extend beyond the first end of the piston body 41. That is, the first segment 45a-1 of the slide rod 45a gradually extends into the compression chamber from the small circular hole 41h-2 of the sliding hole 41h in the piston body 41. During this process, the thermal induction spring 45d begins to exert the shape memory effect (SME) of the shape memory alloy, and the volume of the compressor inside the compressor is V2. The main influencing factor on the volumetric efficiency λ of the piston compressor is the volume coefficient λ. V Pressure coefficient λ P Temperature coefficient λ T Leakage coefficient λ l That is, λ = λV λ P λ T λ l Wherein, the volume coefficient λ V This mainly reflects the magnitude of the influence of clearance volume and compression ratio on volumetric efficiency, which can be expressed as λ. V =1-c(ε) 1 / m -1), where c is the clearance volume, ε is the compression ratio, and m is the polytropic index. It can be seen that as the clearance volume and compression ratio increase, λ V Consequently, the volumetric coefficient λ decreases, especially under high-pressure conditions in low-temperature refrigeration. V The compression ratio is lower, meaning that the compression ratio relative to λ is lower at this point. V The influence of the compression ratio begins to dominate. Therefore, when the compression ratio increases, the adverse effects of the increased compression ratio can be partially or completely offset by reducing the size of the clearance volume, so that the volume of the compression chamber V2 < V1. In this way, the increase in compression ratio has a smaller impact on the volume coefficient λ. V The impact will gradually decrease, and the compressor's volumetric efficiency λ will only be slightly adversely affected or completely unaffected. At this point, the actual pressure-volume (PV) of the piston compressor during operation will be as follows: Figure 13 As shown, the intake process is curve 4'~1, the compression process is curve 1~2', the exhaust process is curve 2'~3, and the expansion process is curve 3~4'. That is, the PV change of the piston compressor at this time is a closed loop curve 4'~1~2'~3 that repeats repeatedly.

[0082] like Figure 12 As shown, when the compressor operates under high frequency and high speed conditions, the temperature generated by the compressed gas or refrigerant and the temperature generated by mechanical friction reach their highest levels. This temperature is significantly higher than the austenitic temperature line Ac of the shape memory alloy base material of the thermal induction spring 45d. At this time, the thermal induction spring 45d is in a fully extended state, while the mechanical spring 45b is in a fully contracted state. This causes the slide rod 45a to extend to its maximum extent beyond the first end of the piston body 41. Specifically, the first segment 45a-1 of the slide rod 45a extends to its maximum extent from the small circular hole 41h-2 of the sliding hole 41h in the piston body 41 into the compression chamber. During this process, the thermal induction spring 45d fully utilizes the shape memory effect (SME) of the shape memory alloy, and the volume of the compressor inside the compressor is V3. The main influencing factor on the volumetric efficiency λ of the piston compressor is the volume coefficient λ. V Pressure coefficient λ P Temperature coefficient λ T Leakage coefficient λ l That is, λ = λ V λ P λ T λ l Wherein, the volume coefficient λ VThis mainly reflects the magnitude of the influence of clearance volume and compression ratio on volumetric efficiency, which can be expressed as λ. V =1-c(ε) 1 / m -1), where c is the clearance volume, ε is the compression ratio, and m is the polytropic index. It can be seen that as the clearance volume and compression ratio increase, λ V Consequently, the volumetric coefficient λ decreases, especially under high-pressure conditions in low-temperature refrigeration. V The compression ratio is lower, meaning that the compression ratio relative to λ is lower at this point. V The influence of the compression ratio begins to dominate. Therefore, when the compression ratio increases, the adverse effects of the increased compression ratio can be partially or completely offset by reducing the size of the clearance volume, so that the volume of the compression chamber V2 < V1. In this way, the increase in compression ratio has a smaller impact on the volume coefficient λ. V The impact will gradually decrease, and the compressor's volumetric efficiency λ will only be slightly adversely affected or completely unaffected. At this point, the actual pressure-volume (PV) of the piston compressor during operation will be as follows: Figure 13 As shown, the intake process is curve 4”~1, the compression process is curve 1~2”, the exhaust process is curve 2”~3, and the expansion process is curve 3~4”. That is, the PV change of the piston compressor at this time is a closed loop curve 4”~1~2”~3 that repeats repeatedly.

[0083] When the piston compressor switches from high frequency to low frequency operation, or stops directly after switching from high frequency / medium frequency operation, the thermal spring 45d no longer tends to elongate, but instead tends to return to its original contracted state. Therefore, it will no longer exert force on the mechanical spring 45b. Moreover, the force exerted by the thermal spring 45d at this time is less than the force of the mechanical spring 45b. The thermal spring 45d will be gradually compressed by the force of the mechanical spring 45b until it is completely compressed and returns to its original contracted state. During this process, the thermal spring 45b plays the role of superelasticity (SE) of the shape memory alloy.

[0084] Another implementation scenario, in Figure 6 Based on this, the positions of the thermal induction spring 45d and the mechanical spring 45b are interchanged. The thermal induction spring 45d shortens when heated, while the mechanical spring 45b is stretched. The austenite temperature line Ac of the selected shape memory alloy is within the operating temperature range of the compressor, which is approximately room temperature to 200°C. When the temperature inside the compressor is higher than this austenite temperature line Ac, the shape memory alloy gradually transforms from the martensite phase to the austenite phase; when the temperature inside the compressor is lower than this austenite temperature line Ac, the shape memory alloy gradually transforms from the austenite phase to the martensite phase, thereby achieving the purpose of causing the thermal induction spring to deform and contract.

[0085] The process is as follows:

[0086] When the compressor is running at low frequency and low speed, the temperature of the compressed gas or refrigerant and the temperature generated by mechanical friction are relatively low, and the temperature does not reach the austenite temperature line Ac of the base material of the memory alloy of the thermal induction spring 45b. At this time, the thermal induction spring 45b is in an elongated state, and the mechanical spring 45d is in a compressed state. At this time, the end surface 45a-3 of the first end of the slide rod 45a is flush with the first end surface of the piston body 41, that is, the first rod segment 45a-1 of the slide rod 45a is still completely in the small circular hole 41h-2 of the sliding hole 41h of the piston body 41, and the volume of the compressor in the compressor is V1. At this time, the actual pressure-volume (P-V) of the piston compressor during operation is as shown in FIG. 4, the suction process is curve 4-1, the compression process is curve 1-2, the exhaust process is curve 2-3, and the expansion process is curve 3-4, that is, the P-V change of the operation of the piston compressor at this time is a closed loop curve 4-1-2-3 in repeated cycles. Figure 13

[0087] When the compressor is running at medium frequency and medium speed, the temperature of the compressed gas or refrigerant and the temperature generated by mechanical friction gradually increase, and the temperature is slightly greater than the austenite temperature line Ac of the base material of the memory alloy of the thermal induction spring 45b. At this time, the thermal induction spring 45b gradually contracts, the mechanical spring 45d gradually elongates, and further causes the slide rod 45a to gradually extend out of the front end surface of the piston body 41, that is, the first rod segment 45a-1 of the slide rod 45a gradually extends from the small circular hole 41h-2 of the sliding hole 41h of the piston body 41 into the compression chamber. During this process, the thermal induction spring 45b begins to play a role of the shape memory effect (SME) of the memory alloy, and the volume of the compressor in the compressor is V2. The main influencing factors of the volumetric efficiency λ of the piston compressor include the volumetric coefficient λ V , the pressure coefficient λ P , the temperature coefficient λ T , and the leakage coefficient λ l , that is, λ = λ V λ P λ T λ l , wherein the volumetric coefficient λ V mainly reflects the influence of the clearance volume and the compression ratio on the volumetric efficiency, and can be expressed as λ V = 1-c(ε 1 / m -1), wherein c is the clearance volume, ε is the compression ratio, and m is a variable index. It can be known that as the clearance volume and the compression ratio increase, λ V decreases, and in particular, in the high-pressure ratio working condition of low-temperature refrigeration, the volumetric coefficient λ V is low, that is, the compression ratio has a great influence on λ V ​The influence of the compression ratio begins to dominate. Therefore, when the compression ratio increases, the adverse effects of the increased compression ratio can be partially or completely offset by reducing the size of the clearance volume, so that the volume of the compression chamber V2 < V1. In this way, the increase in compression ratio has a smaller impact on the volume coefficient λ. V The impact will gradually decrease, and the compressor's volumetric efficiency λ will only be slightly adversely affected or completely unaffected. At this point, the actual pressure-volume (PV) of the piston compressor during operation will be as follows: Figure 10 As shown, the intake process is curve 4'~1, the compression process is curve 1~2', the exhaust process is curve 2'~3, and the expansion process is curve 3~4'. That is, the PV change of the piston compressor at this time is a closed loop curve 4'~1~2'~3 that repeats repeatedly.

[0088] like Figure 12 As shown, when the compressor operates under high frequency and high speed conditions, the temperature generated by the compressed gas or refrigerant and the temperature generated by mechanical friction reach their highest levels. This temperature is significantly higher than the austenitic temperature line Ac of the shape memory alloy base material of the thermal induction spring 45b. At this time, the thermal induction spring 45b is in a fully contracted state, and the mechanical spring 45d is in a fully extended state. This causes the slide rod 45a to extend to its maximum extent beyond the first end of the piston body 41. That is, the first segment 45a-1 of the slide rod 45a extends into the compression chamber through the small circular hole 41h-2 of the sliding hole 41h in the piston body 41. During this process, the thermal induction spring 45b fully utilizes the shape memory effect (SME) of the shape memory alloy, and the volume of the compressor inside the compressor is V3. The main influencing factor on the volumetric efficiency λ of the piston compressor is the volume coefficient λ. V Pressure coefficient λ P Temperature coefficient λ T Leakage coefficient λ l That is, λ = λ V λ P λ T λ l Wherein, the volume coefficient λ V This mainly reflects the magnitude of the influence of clearance volume and compression ratio on volumetric efficiency, which can be expressed as λ. V =1-c(ε) 1 / m -1), where c is the clearance volume, ε is the compression ratio, and m is the polytropic index. It can be seen that as the clearance volume and compression ratio increase, λ V Consequently, the volumetric coefficient λ decreases, especially under high-pressure conditions in low-temperature refrigeration. V The compression ratio is lower, meaning that the compression ratio relative to λ is lower at this point. V The influence of the compression ratio begins to dominate. Therefore, when the compression ratio increases, the adverse effects of the increased compression ratio can be partially or completely offset by reducing the size of the clearance volume, so that the volume of the compression chamber V2 < V1. In this way, the increase in compression ratio has a smaller impact on the volume coefficient λ.V The influence of the heat will gradually decrease, and the volumetric efficiency λ of the compressor will only be slightly affected or not affected at all. The actual pressure-volume (P-V) of the piston compressor at this time is shown in Fig. 4, wherein the suction process is curve 4"~1, the compression process is curve 1~2", the discharge process is curve 2"~3, and the expansion process is curve 3~4", i.e., the P-V change of the piston compressor at this time is a closed loop curve 4"~1~2"~3. Figure 13

[0089] When the piston compressor is switched from high frequency to low frequency, or is directly stopped after running at high frequency / medium frequency, the thermal responsive spring 45b has been contracted to the limit state and has a tendency to gradually restore the original elongation state. At this time, the force generated by the thermal responsive spring 45b is greater than the force of the mechanical spring 45d, and the mechanical spring 45d will be gradually compressed by the force of the thermal responsive spring 45b until it is completely compressed and restored to the original contraction state of the mechanical spring 45d. In this process, the thermal responsive spring 45b plays a super-elasticity (SE) role of a memory alloy.

[0090] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application. The above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A piston for a piston compressor, which piston compressor is formed with a compression chamber (2), characterised in that The piston body (41) is provided with a pressurized end face (3) at the axial first end, which is used to pressurize the fluid in the compression cavity (2); a sliding hole (41h) is arranged on the pressurized end face (3), and a sliding rod (45a) is arranged in the sliding hole (41h); the first end of the sliding rod (45a) can gradually extend into the compression cavity (2) as the temperature in the compression cavity (2) rises; the sliding rod (45a) gradually retracts into the sliding hole (41h) as the temperature in the compression cavity (2) falls; a thermal sensitive spring (45d) is arranged in the sliding hole (41h), and an elastic member is also arranged in the sliding hole (41h), and the thermal sensitive spring (45d) can be elongated to compress the elastic member; the inner wall surface of the sliding hole (41h) comprises a first step surface (41h-3) facing away from the compression cavity (2); the second end of the sliding rod (45a) is provided with a rod head (45c), and the rod head (45c) is formed with a second step surface (45c-4) facing away from the first end of the sliding rod (45a); when the sliding rod (45a) is inserted into the sliding hole (41h), a second interval (102) is formed between the first step surface (41h-3) and the second step surface (45c-4), and the elastic member is a mechanical spring (45b) arranged in the second interval (102) and sleeved on the sliding rod (45a); the two ends of the mechanical spring (45b) are respectively in contact with the first step surface (41h-3) and the end surface of the rod head (45c) opposite to the second step surface (45c-4). The first end of the thermal sensitive spring (45d) is fixedly connected with the sliding rod (45a), and the second end of the thermal sensitive spring (45d) is fixedly connected with the inner wall surface of the sliding hole (41h); the length of the thermal sensitive spring (45d) can increase as the temperature in the compression cavity (2) rises to push the first end of the sliding rod (45a) to extend into the compression cavity (2). The first end of the thermal sensitive spring (45d) is fixedly connected with the sliding rod (45a), and the second end of the thermal sensitive spring (45d) is fixedly connected with the inner wall surface of the sliding hole (41h); the length of the thermal sensitive spring (45d) can increase as the temperature in the compression cavity (2) rises to push the first end of the sliding rod (45a) to extend into the compression cavity (2). The first end of the thermal sensitive spring (45d) is fixedly connected with the sliding rod (45a), and the second end of the thermal sensitive spring (45d) is fixedly connected with the inner wall surface of the sliding hole (41h); the length of the thermal sensitive spring (45d) can increase as the temperature in the compression cavity (2) rises to push the first end of the sliding rod (45a) to extend into the compression cavity (2). ​ ​ ​ ​ 2. The piston of claim 1 wherein, ​ ​ 3. The piston of claim 1 wherein, ​ ​ 4. The piston of claim 2 wherein, The sliding hole (41h) is a through hole penetrating through both axial ends of the piston, and an end of the sliding hole (41h) away from the compression cavity (2) is sealed by a screw (46); when the sliding rod (45a) is arranged in the sliding hole (41h), a first interval (101) is formed between the screw (46) and an end of the sliding rod (45a) away from the compression cavity (2), and the heat-sensitive spring (45d) is arranged in the first interval (101).

5. The piston of claim 4 wherein, An end of the first end of the sliding rod (45a) is provided with a buffer part.

6. The piston of claim 1 wherein, The sliding rod (45a) comprises a first rod segment (45a-1) and a second rod segment (45a-2), a cross-sectional area of the first rod segment (45a-1) is greater than that of the second rod segment (45a-2), and the sliding rod (45a) is fixedly connected with the rod head (45c) through the second rod segment (45a-2).

7. The piston of claim 6 wherein, The rod head (45c) is provided with a protrusion (45c-2) protruding away from the sliding rod (45a).

8. A compressor characterized by, The piston comprises the piston according to any one of claims 1-7.

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