Piston assembly and air compressor

Abstract

The embodiment of the invention provides a piston assembly and an air compressor. The piston assembly comprises: a piston; the piston is used for being arranged in an air cylinder of the air compressor; the packing cup comprises a bottom wall and a side wall, the bottom wall is fixedly connected to the piston, the side wall is arranged on the outer side of the piston in a sleeving mode, and a gap is formed between the side wall and the piston; the side wall is used for being in elastic contact with the inner wall of the air cylinder; wherein the width of the gap is l1, and the preset range meets the conditions that l1 is larger than h * sin alpha, and l1 is larger than r1-s-r2 * cos alpha-h * sin alpha. According to the piston assembly, the overall performance of the air compressor can be improved, and the service life of the air compressor can be prolonged.

Description

Technical Field

[0001] The present application belongs to the technical field of air compressors, and in particular relates to a piston assembly and an air compressor. Background Art

[0002] An air compressor is a mechanical device that compresses air to a higher pressure and is widely used in a variety of industries and fields. The cylinder of an air compressor is equipped with a piston assembly and a leather cup. The gas is compressed by the reciprocating motion of the piston assembly in the cylinder. The leather cup is a key sealing component. Its function is to prevent the gas inside the cylinder from leaking during the movement of the piston assembly, thereby ensuring the efficient operation of the compressor.

[0003] However, the existing leather cups are prone to problems such as poor sealing and leather cup wear after long-term use, which reduces the service life and sealing performance of the leather cups, thereby affecting the overall performance and life of the air compressor. Summary of the invention

[0004] The present application aims to provide a piston assembly and an air compressor to solve the problem that the leather cup of the existing piston assembly has a low service life and sealing performance, which affects the overall performance and life of the air compressor.

[0005] In order to solve the above technical problems, this application is implemented as follows:

[0006] In a first aspect, the present application discloses a piston assembly, the piston assembly comprising:

[0007] A piston, the piston being arranged in a cylinder of an air compressor;

[0008] and a leather cup, the leather cup comprising a bottom wall and a side wall surrounding the bottom wall, the bottom wall being fixedly connected to the piston, the side wall being sleeved on the radially outer side of the piston, and a gap being provided between the side wall and the piston; the side wall being used for elastically contacting with the inner wall of the cylinder; wherein the width of the gap is l1, and l1 satisfies: l1>h·sinα and l1>r1-s-r2·cosα-h·sinα;

[0009] Among them, h is the height of the leather cup, α is the maximum deflection angle of the piston in the cylinder; r1 is the radius of the cylinder; r2 is the radius of the piston, and s is the wall thickness of the side wall.

[0010] Optionally, a mounting groove is provided on the piston, and the bottom wall is fixedly disposed in the mounting groove.

[0011] Optionally, the bottom wall is welded in the mounting groove.

[0012] Optionally, the wall thickness of the bottom wall is the same as the wall thickness of the side wall.

[0013] Optionally, the piston assembly further comprises a connecting rod, wherein the connecting rod and the piston are formed integrally, and an interface portion is provided at one end of the connecting rod away from the piston, and the interface portion is used to be connected to a driving mechanism in the air compressor.

[0014] Optionally, the connecting rod and the piston are integrally injection molded.

[0015] Optionally, the piston assembly also includes a slice, the piston includes a first end face, a second end face and an intake channel, the first end face and the second end face are arranged in a direction opposite to each other along the axial direction of the piston, the intake channel runs through the first end face and the second end face, the slice is arranged on the first end face through a fastener, and the slice is used to cover the intake channel on the first end face.

[0016] In a second aspect, the present application further discloses an air compressor, which comprises: a piston assembly as described in any one of the above items.

[0017] Optionally, the air compressor includes a cylinder and a driving mechanism, the piston assembly is located in the cylinder and connected to the driving mechanism, and the driving mechanism is used to drive the piston assembly to move in the cylinder.

[0018] Optionally, the driving mechanism includes a crankshaft, and the connecting rod of the piston assembly is connected to the crankshaft. The rotation of the crankshaft drives the connecting rod to move in the cylinder. The eccentricity of the crankshaft is R, the length of the connecting rod is L, and the maximum deflection angle of the piston in the cylinder is α=arcsin(R / L).

[0019] In the embodiment of the present application, by making the gap width l1 between the leather cup and the piston satisfy l1>h·sinα and l1>r1-s-r2·cosα-h·sinα, the leather cup can always be in contact with the inner wall of the cylinder during the movement of the piston, thereby reducing gas leakage, improving the sealing performance of the leather cup, and reducing the collision between the leather cup and the piston during the movement of the piston, reducing the wear of the leather cup, and extending the service life of the leather cup, thereby improving the overall performance and life of the air compressor.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0022] Figure 1is a structural schematic diagram of a piston assembly described in an embodiment of the present application;

[0023] Figure 2 It is a schematic diagram of the structural decomposition of a piston assembly described in an embodiment of the present application;

[0024] Figure 3 It is a schematic diagram of the leather cup structure of a piston assembly described in an embodiment of the present application;

[0025] Figure 4 is a cross-sectional schematic diagram of a piston assembly shown in an embodiment of the present application;

[0026] Figure 5 It is a cross-sectional schematic diagram of a piston assembly and a cylinder described in an embodiment of the present application;.

[0027] Figure numerals: 10 - piston, 101 - mounting groove; 102 - air intake channel; 20 - leather cup; 201 - bottom wall; 202 - side wall; 30 - connecting rod; 301 - interface; 40 - scriber; 50 - fastener; 1 - cylinder. DETAILED DESCRIPTION

[0028] Embodiments of the present invention will be described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] The term "first" or "second" in the specification and claims of the present application may include one or more of the features explicitly or implicitly. In the description of the present invention, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0030] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The embodiment of the present application provides a piston assembly, and in practical applications, the piston assembly can be used in an air compressor. The piston assembly of the present application is described in detail below in conjunction with the accompanying drawings.

[0033] See also Figure 1-Figure 5 The piston assembly described in the embodiment of the present application may include: a piston 10, which is used to be arranged in the cylinder 1 of the air compressor; and a leather cup 20, which includes a bottom wall 201 and a side wall 202 surrounding the bottom wall 201, the bottom wall 201 is fixedly connected to the piston 10, the side wall 202 is sleeved on the radial outer side of the piston 10, and there is a gap between the side wall 202 and the piston 10; the side wall 202 is used to elastically contact with the inner wall of the cylinder 1; wherein the width of the gap is l1, and l1 satisfies: l1>h·sinα and l1>r1-s-r2·cosα-h·sinα; wherein h is the height of the leather cup 20, α is the maximum deflection angle of the piston 10 in the cylinder 1; r1 is the radius of the cylinder 1; r2 is the radius of the piston 10, and s is the wall thickness of the side wall 202.

[0034] Specifically, if Figure 1-Figure 5 As shown, the piston 10 is a cylindrical structural component, which is used to be installed in the cylinder 1 of the air compressor. By closely fitting with the inner wall of the cylinder 1, a closed space is formed for compressing the gas. The reciprocating linear motion of the piston 10 in the cylinder 1 realizes the suction and compression of the gas.

[0035] The leather cup 20 includes a bottom wall 201 and an annular side wall 202. The bottom wall 201 is fixed on the piston 10, so that the leather cup 20 can be fixed on the piston 10 to prevent the leather cup 20 from falling off during the movement of the piston 10. The annular side wall 202 is sleeved on the radial outer side of the piston 10. The radial outer surface of the side wall 202 can elastically contact with the inner wall of the cylinder 1, and can seal the gap between the piston 10 and the cylinder 1 to prevent gas leakage during the reciprocating movement of the piston 10.

[0036] There is a gap between the radial inner surface of the side wall 202 and the piston 10, which allows a certain amount of interference between the leather cup 20 and the cylinder 1, so that after the piston 10 enters the cylinder 1, the outer surface of the leather cup 20 can be close to the inner wall surface of the cylinder 1 to play a sealing role. In actual applications, a too small gap will increase the friction between the side wall 202 of the leather cup 20 and the piston 10, shortening the service life of the leather cup 20, and a too large gap will lead to insufficient contact between the side wall 202 of the leather cup 20 and the inside of the cylinder 1, resulting in poor sealing.

[0037] like Figure 5 As shown, when the axis of the piston 10 is parallel to the central axis of the cylinder 1, the side wall 202 of the leather cup 20 is pressed against the inner wall of the cylinder 1 by its own elastic force. At this time, the gap width is defined as the radial straight-line distance l1 between the radial inner surface of the side wall 202 and the radial outer surface of the piston 10 when the piston assembly is inside the cylinder 1.

[0038] Specifically, the piston 10 can be connected to the crankshaft in the air compressor. The crankshaft can be driven to rotate by a motor or other power source. A crank is installed on the crankshaft, and the crank has an eccentric moment R. When the crankshaft rotates, the crank can convert the rotational motion of the crankshaft into the reciprocating linear motion of the piston 10 through the eccentricity R. However, in this process, the movement of the piston 10 is not always along the axial direction of the cylinder 1, but deflects with the rotation of the crankshaft. The piston 10 will also swing under the drive of the connecting rod 30. During the swinging process, the side walls 202 at both ends of the leather cup 20 in the radial direction are not subjected to the same force, such as Figure 5As shown, on the left side in the radial direction, the side wall 202 is in a compressed state. At this time, the gap width l1 between the side wall 202 and the piston 10 is small. During the movement of the piston 10, the side wall 202 and the piston 10 may come into contact. In this way, the side wall 202 is repeatedly squeezed by the piston 10 during the movement, loses its original elasticity and cannot effectively maintain close contact with the inside of the cylinder 1. Repeated squeezing will also cause the material of the side wall 202 of the leather cup 20 to gradually wear, reducing the service life of the leather cup 20. On the right side in the radial direction, the side wall 202 is in a stretched state. At this time, the gap width l1 between the side wall 202 and the piston 10 is large. The side wall 202 cannot rely on its own resilience to make the side wall 202 close to the inner wall of the cylinder 1, which will cause the side wall 202 of the leather cup 20 to be out of contact with the inner wall of the cylinder 1, and cannot form an effective seal, resulting in gas leakage.

[0039] like Figure 5 As shown, the radius of the cylinder 1 is defined as r1, the radius of the piston 10 is defined as r2, the axial height of the leather cup 20 is defined as h, the wall thickness of the side wall 202 is defined as s, and the maximum deflection angle of the piston 10 in the cylinder 1 is defined as α, wherein the eccentricity of the crank is defined as R, the length of the connecting rod 30 is defined as L, and the maximum deflection angle of the piston 10 in the cylinder 1 is defined as α=arcsin(R / L).

[0040] When the side wall 202 is in a compressed state, it is calculated that when l1=hsinα, the side wall 202 and the piston 10 are just in contact. Therefore, in order to avoid contact between the side wall 202 and the piston 10, it is required that l1>h·sinα; when the side wall 202 is in a stretched state, it is calculated that when l1=r1-s-r2·cosα-h·sinα, the side wall 202 is just unable to adhere to the inner wall of the cylinder 1 based on its own rebound force. Therefore, in order to avoid the side wall 202 from being out of contact with the inner wall of the cylinder 1, it is required that l1>r1-s-r2·cosα-h·sinα. In the embodiment of the present application, by making the gap width l1 between the side wall 202 and the piston 10 satisfy both l1>h·sinα and l1>r1-s-r2·cosα-h·sinα, the leather cup 20 can always be in contact with the inner wall of the cylinder 1 during the movement of the piston 10, thereby reducing gas leakage, improving the sealing performance of the leather cup 20, and reducing the collision between the leather cup 20 and the piston 10 during the movement of the piston 10, reducing the wear of the leather cup 20, and extending the service life of the leather cup 20, thereby improving the overall performance and life of the air compressor.

[0041] In some optional embodiments, a mounting groove 101 is provided on the piston 10 , and the bottom wall 201 is fixedly disposed in the mounting groove 101 .

[0042] Specifically, the outer surface of the piston 10 is recessed radially along the piston 10 to form an annular mounting groove 101, and the bottom wall 201 of the leather cup 20 has a through hole in the middle thereof. The through hole is used to allow the bottom wall 201 to pass through the piston 10 and be set in the annular mounting groove 101. The bottom wall 201 is fixedly set in the mounting groove 101. In actual application, by setting the mounting groove 101, the leather cup 20 can be fixed on the piston 10 to ensure that the leather cup 20 will not fall off during the movement of the piston 10, thereby increasing the stability of the system. In addition, by directly setting the mounting groove 101 on the piston 10 to fix the leather cup 20, the installation process of the leather cup 20 is simpler and faster, thereby reducing the production cost.

[0043] Optionally, the bottom wall 201 is welded in the mounting groove 101 .

[0044] Specifically, the bottom wall 201 can be fixedly connected to the mounting groove 101 of the piston 10 by ultrasonic welding. In practical applications, by directly welding the bottom wall 201 to the mounting groove 101 of the piston 10, no additional fixing parts are required, so that the structure of the piston assembly is simpler and the cost of the piston assembly is reduced.

[0045] Optionally, the wall thickness of the bottom wall 201 is the same as the wall thickness of the side wall 202 .

[0046] Specifically, if Figure 3 and Figure 5 As shown, the wall thickness of the side wall 202 is the same as that of the bottom wall 201, that is, the thickness of the leather cup 20 is consistent. In practical applications, since the processing technology of the leather cup 20 with consistent thickness is relatively simple, the processing process of the piston assembly can be simplified, further reducing costs.

[0047] Optionally, the piston assembly further comprises a connecting rod 30 , wherein the connecting rod 30 and the piston 10 are formed as one piece, and an interface portion 301 is provided at one end of the connecting rod 30 away from the piston 10 , and the interface portion 301 is used to connect with a driving mechanism in the air compressor.

[0048] Specifically, if Figure 1 and Figure 2As shown, the piston 10 and the interface portion 301 are respectively located at the two ends of the connecting rod 30. For example, the piston 10 is located at the front end of the connecting rod 30 for extending into the cylinder 1, and the interface portion 301 is located at the rear end of the connecting rod 30 for connecting with the driving mechanism in the air compressor. The driving mechanism drives the connecting rod 30 to move, and then drives the piston 10 to move in the cylinder 1. In actual applications, the piston 10, the interface portion 301 and the connecting rod 30 are an integrally formed structure, which simplifies the production process of the piston assembly and improves the production process of the piston assembly. The integrally formed piston assembly reduces the number of repairs and replacements caused by the failure of the connector during long-term operation, thereby extending the service life of the piston assembly.

[0049] It should be noted that the specific structure of the interface portion 301 is compatible with the specific structure of the connection portion of the driving mechanism, and the embodiment of the present application does not make any specific limitation on this.

[0050] Optionally, the connecting rod 30 is integrally formed with the piston 10 by injection molding. In practical applications, the connecting rod 30 and the piston 10 are integrally formed by injection molding, so that the overall structure of the piston 10 and the connecting rod 30 is integrated. Since the injection molding process is simple and low in cost, the production process of the piston assembly can be simplified and the production cost of the piston assembly can be reduced.

[0051] Optionally, the piston assembly also includes a slice 40, the piston 10 includes a first end face, a second end face and an intake channel 102, the first end face and the second end face are arranged in a direction opposite to each other along the axial direction of the piston 10, the intake channel 102 passes through the first end face and the second end face, the slice 40 is movably connected to the first end face by a fastener 50, and the slice 40 is used to cover the intake channel 102 on the first end face.

[0052] Specifically, the front end of the piston 10 along the axial direction has a first end face, and the rear end has a second end face. An intake passage 102 is formed inside the piston 10, and the intake passage 102 runs through the first end face and the second end face. External air can enter the cylinder 1 through the intake passage 102. The slice 40 is fixedly arranged on the first end face of the piston 10 by a fastener 50, and the slice 40 covers the intake passage 102 on the first end face. There may be a certain movable space between the slice 40 and the first end face. Under the action of gas, the slice 40 can be close to the first end face or away from the first end face to close or open the intake passage 102. In actual application, during the compression process, the compression force of the gas presses the slice 40 against the first end face, and the intake passage 102 can be closed, and a good seal is formed at this time. During the air intake process, the gas can drive the scriber 40 away from the first end surface, so that a gap is formed between the scriber 40 and the first end surface, and the air intake channel 102 can be opened. At this time, air intake can be achieved through the air intake channel 102. The scriber 40 can automatically adjust the opening and closing state according to the gas pressure, which can avoid the reduction of the sealing effect caused by the continuous deformation of the sealing sheet in the traditional piston assembly, thereby improving the reliability of the piston assembly. The fastener 50 can be a bolt.

[0053] Furthermore, the scriber 40 may be a rigid scriber 40. For example, the scriber 40 may be made of stainless steel to ensure the strength of the scriber 40 and avoid poor sealing caused by deformation of the scriber 40.

[0054] In summary, the piston assembly described in the embodiment of the present application may at least include the following advantages:

[0055] In the embodiment of the present application, by making the gap width l1 between the side wall 202 and the piston 10 simultaneously satisfy l1>h·sinα and l1>r1-s-r2·cosα-h·sinα, the leather cup 20 can always be in contact with the inner wall of the cylinder 1 during the movement of the piston 10, thereby reducing gas leakage, improving the sealing performance of the leather cup 20, and reducing the collision between the leather cup 20 and the piston 10 during the movement of the piston 10, reducing the wear of the leather cup 20, and extending the service life of the leather cup 20, thereby improving the overall performance and life of the air compressor.

[0056] The embodiment of the present application further discloses an air compressor, which may specifically include the piston assembly described in any of the embodiments.

[0057] It should be noted that in the embodiment of the present application, the structure of the piston assembly is the same as the structure of the piston assembly in any of the above embodiments, and its beneficial effects are also similar, which will not be repeated here.

[0058] Optionally, the air compressor includes a cylinder 1 and a driving mechanism, the piston assembly is located in the cylinder 1 and connected to the driving mechanism, and the driving mechanism is used to drive the piston assembly to move in the cylinder 1.

[0059] Specifically, the cylinder 1 is used to accommodate the reciprocating motion of the piston assembly. The connecting rod 30 in the piston assembly is connected to the driving mechanism. The driving mechanism is used to drive the piston assembly to reciprocate in the cylinder 1 to achieve compression of the gas in the cylinder 1.

[0060] Optionally, the driving mechanism includes a crankshaft and a crank arranged on the crankshaft, the connecting rod 30 of the piston assembly is connected to the crankshaft, the rotation of the crankshaft drives the connecting rod 30 to move in the cylinder 1, the eccentricity of the crank is R, the length of the connecting rod 30 is L, and the maximum deflection angle α of the piston 10 in the cylinder 1 is arcsin (R / L).

[0061] Specifically, the connecting rod 30 in the piston assembly is fixed on the crankshaft, and the crankshaft can be driven to rotate by a motor or other power source. A crank is installed on the crankshaft, and the crank has an eccentric moment R. When the crankshaft rotates, the crank can convert the rotational motion of the crankshaft into the reciprocating linear motion of the connecting rod 30 through the eccentricity R, and then drive the piston 10 to move linearly in the cylinder 1. During this process, the movement of the connecting rod 30 is not always along the axial direction of the cylinder 1, but deflects with the rotation of the crankshaft. The piston 10 will also deflect under the drive of the connecting rod 30. For the same air compressor, its eccentricity R and the axial length L of the connecting rod 30 along the piston 10 are both fixed values. The maximum deflection angle α of the piston 10 in the cylinder 1 can be calculated by the length L of the connecting rod 30 and the eccentricity R through the formula α=arcsin(R / L).

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0063] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A piston assembly, characterized in that: The piston assembly comprises: A piston (10), the piston (10) being arranged in a cylinder (1) of an air compressor; and a leather cup (20), the leather cup (20) comprising a bottom wall (201) and a side wall (202) surrounding the bottom wall (201), the bottom wall (201) being fixedly connected to the piston (10), the side wall (202) being sleeved on the radially outer side of the piston (10), and a gap being provided between the side wall (202) and the piston (10); the side wall (202) being used for elastically contacting with the inner wall of the cylinder (1); The width of the gap is l1, and l1 satisfies: l1>h·sinα and l1>r1-s-r2·cosα-h·sinα; Wherein, h is the height of the leather cup (20), α is the maximum deflection angle of the piston (10) in the cylinder (1); r1 is the radius of the cylinder (1); r2 is the radius of the piston (10), and s is the wall thickness of the side wall (202).

2. The piston assembly according to claim 1, characterized in that The piston (10) is provided with a mounting groove (101), and the bottom wall (201) is fixedly arranged in the mounting groove (101).

3. The piston assembly according to claim 2, characterized in that The bottom wall (201) is welded in the installation groove (101).

4. The piston assembly according to claim 1, characterized in that The wall thickness of the bottom wall (201) is the same as the wall thickness of the side wall (202).

5. The piston assembly according to claim 1, characterized in that The piston assembly further comprises a connecting rod (30), wherein the connecting rod (30) and the piston (10) are formed in one piece, and an interface portion (301) is provided at one end of the connecting rod (30) away from the piston (10), wherein the interface portion (301) is used to connect to a driving mechanism in an air compressor.

6. The piston assembly according to claim 5, characterized in that The connecting rod (30) and the piston (10) are integrally injection molded.

7. The piston assembly according to claim 1, characterized in that The piston assembly further comprises a scriber (40), the piston (10) comprising a first end face, a second end face and an air intake passage (102), the first end face and the second end face being arranged in a direction away from each other along the axial direction of the piston (10), the air intake passage (102) passing through the first end face and the second end face, the scriber (40) being movably connected to the first end face via a fastener (50), and the scriber (40) being used to cover the air intake passage (102) on the first end face.

8. An air compressor, characterized in that: The air compressor comprises the piston assembly as described in any one of claims 1 to 7.

9. The air compressor according to claim 8, characterized in that: The air compressor comprises a cylinder (1) and a driving mechanism, the piston assembly is located in the cylinder (1) and is connected to the driving mechanism, and the driving mechanism is used to drive the piston assembly to move in the cylinder (1).

10. The air compressor according to claim 9, characterized in that: The driving mechanism comprises a crankshaft and a crank arranged on the crankshaft, the connecting rod (30) of the piston assembly is connected to the crankshaft, the crankshaft rotates to drive the connecting rod (30) to move in the cylinder (1), the eccentricity of the crank is R, the length of the connecting rod (30) is L, and the maximum deflection angle α of the piston (10) in the cylinder (1) is arcsin (R / L).

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