A Stirling refrigerator

Abstract

The present invention discloses a Stirling refrigerator, comprising: a compression mechanism and an expansion mechanism of equal mass, the compression mechanism including a compression connecting rod assembly, which performs piston motion when the compression mechanism rotates, and the expansion mechanism including an expansion connecting rod assembly, which performs piston motion when the expansion mechanism rotates; a cam shaft driven to rotate by a motor, the compression connecting rod assembly and the expansion connecting rod assembly both being sleeved on the cam shaft and maintaining an axial projection angle of 90° on the cam shaft; the cam shaft including a recessed area arranged in the direction of the angular bisector extending from the axis of the compression mechanism and the axis of the expansion mechanism. The present invention designs the compression mechanism and the expansion mechanism to be structures of equal mass so that the direction of the resultant inertial force of the compression mechanism and the expansion mechanism remains unchanged during operation, and simultaneously provides a recessed area on the cam shaft to reduce the centrifugal force during the rotation of the cam shaft, thereby balancing the above-mentioned resultant inertial force, thereby achieving a dynamically balanced working state of the Stirling refrigerator.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration equipment, in particular to a Stirling refrigerator. Background Art

[0002] Stirling refrigerators are used to achieve ultra-low temperature environments. Due to their advantages of efficient refrigeration, small size, light weight and low power consumption, they are widely used in the fields of infrared detection and high-temperature superconductivity.

[0003] The Stirling refrigerator uses a rotating motor as a power source and a cam-connecting rod structure to drive the compression cylinder and the expansion cylinder to perform piston motion to perform refrigeration. However, the Stirling refrigerator has a key problem in terms of dynamics, namely, the motion system composed of the cam shaft, the compression connecting rod assembly and the expansion connecting rod assembly. During the rotation of the cam shaft, the compression connecting rod assembly and the expansion connecting rod assembly will be subjected to unbalanced inertial force, and since some structures in the compression connecting rod assembly and the expansion connecting rod assembly continue to rotate, the magnitude and direction of their respective inertial forces are constantly changing. In this case, the rotating motor rotor is in a state of dynamic imbalance, which is manifested in the Stirling refrigerator as follows: 1) The motor vibrates, thereby reducing the motor performance or even causing the motor to freeze; 2) The dynamic imbalance state will accelerate the wear of components such as bearings and expansion pistons, thereby reducing the life of the refrigerator.

[0004] In order to reduce the impact of dynamic imbalance on the refrigerator, the existing technology usually adopts the design method of adding a counterweight block to reduce the dynamic imbalance force of the refrigerator through the gravity of the counterweight block. However, the setting of the counterweight block not only requires bonding and curing with the shaft, but also has great processing difficulty and reduces operating efficiency. In addition, the concentricity of the counterweight block during the assembly process cannot be standardized, resulting in different balancing effects of different refrigerators on the imbalance force.

[0005] Therefore, how to provide a Stirling refrigerator that is in a dynamic equilibrium state during the operation of the refrigerator is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] In view of this, an object of the present invention is to provide a Stirling refrigerator so that the refrigerator operates in a dynamic equilibrium state.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A Stirling refrigerator, comprising:

[0009] A compression mechanism and an expansion mechanism of equal mass, wherein the compression mechanism includes a compression connecting rod assembly, and when the compression connecting rod assembly rotates, the compression mechanism cooperates with the compression cylinder to perform piston motion; and the expansion mechanism includes an expansion connecting rod assembly, and when the expansion connecting rod assembly rotates, the expansion mechanism cooperates with the expansion cylinder to perform piston motion;

[0010] The cam shaft is driven to rotate by a motor, the compression connecting rod assembly and the expansion connecting rod assembly are sleeved on the cam shaft and are transmission-connected to the cam shaft, and the axial projection angle of the compression connecting rod assembly and the expansion connecting rod assembly on the cam shaft is maintained at 90°;

[0011] The cam shaft includes a recessed area, and the recessed area is arranged in a direction extending toward an angle bisector of an axis of the compression mechanism and an axis of the expansion mechanism.

[0012] Preferably, in the above-mentioned Stirling refrigerator, the cam shaft includes a shaft body and a sleeve sleeved on the outer periphery of the shaft body, the recessed area is an arc-shaped recess starting from the first end face of the sleeve and extending toward the second end face of the sleeve, and the sleeve is made of a regular cylinder formed by the first end face and the second end face as two end faces, with the recessed area hollowed out.

[0013] Preferably, in the above Stirling refrigerator, the sleeve is made by hollowing out a region of the regular cylinder that is equivalent to the mass of the expansion mechanism.

[0014] Preferably, in the above-mentioned Stirling refrigerator, the recessed area includes two recessed portions, and the two recessed portions are symmetrically arranged on both end surfaces of the sleeve.

[0015] Preferably, in the above-mentioned Stirling refrigerator, the compression connecting rod assembly and the expansion connecting rod assembly are sleeved on the outer circumference of the sleeve, and the distance between the compression connecting rod assembly and the first end face is equal to the distance between the expansion connecting rod assembly and the second end face.

[0016] Preferably, in the above-mentioned Stirling refrigerator, in the compression mechanism, the compression connecting rod assembly is drivingly connected to the compression plunger via a first connecting pin, and the compression plunger extends into the compression cylinder;

[0017] In the expansion mechanism, the expansion link assembly is transmission-connected to the expansion plunger via a second connecting pin, and the expansion plunger extends into the expansion cylinder.

[0018] Preferably, in the above-mentioned Stirling refrigerator, the compression connecting rod assembly and the expansion connecting rod assembly are mounted on the outer periphery of the cam shaft via bearings.

[0019] The Stirling refrigerator provided by the present invention comprises a compression mechanism, an expansion mechanism and a cam shaft, wherein the compression mechanism comprises a compression connecting rod assembly, which is used to drive other components in the compression mechanism to cooperate with the compression cylinder to perform piston movement through rotational movement. Similarly, the expansion mechanism comprises an expansion connecting rod assembly, which is used to drive other components in the expansion mechanism to cooperate with the expansion cylinder to perform piston movement through rotational movement, thereby achieving refrigeration. In particular, the design masses of the compression mechanism and the expansion mechanism are equal, so that the inertia forces of the compression mechanism and the expansion mechanism are balanced during movement; the cam shaft is driven to rotate by a motor, and at the same time, the compression connecting rod assembly and the expansion connecting rod assembly are sleeved on the outer periphery of the cam shaft so as to be driven to rotate under the rotation of the cam shaft. The compression connecting rod assembly and the expansion connecting rod assembly are arranged on the cam shaft in such a way that the axial projections of the compression connecting rod assembly and the expansion connecting rod assembly on the cam shaft remain at 90°. It should be noted that the compression mechanism and the expansion mechanism are The piston movement mode is an alternating movement identical to that of the prior art, i.e., when the compression mechanism moves to its top dead center position or bottom dead center position during the piston movement, the expansion mechanism moves to the midpoint position of the piston stroke, and when the expansion mechanism moves to its top dead center position or bottom dead center position during the piston movement, the compression mechanism moves to the midpoint position of the piston stroke, thereby ensuring that the direction of the resultant inertial force of the compression mechanism and the expansion mechanism, which have the same mass and a positional relationship of 90°, remains consistent during the movement, i.e., along the direction of the angular bisector of the compression mechanism axis and the expansion mechanism axis; further, the cam shaft includes a recessed area, which is arranged in the direction extending toward the angular bisector of the compression mechanism axis and the expansion mechanism axis, so as to reduce the centrifugal force of the cam shaft in the direction extending toward the angular bisector of the compression mechanism axis and the expansion mechanism axis during rotation, and the resultant inertial force of the compression mechanism and the expansion mechanism is offset and balanced by reducing the centrifugal force, so as to reduce the dynamic imbalance state during the operation of the refrigerator.

[0020] The Stirling refrigerator provided by the present invention designs the compression mechanism and the expansion mechanism that perform alternate piston motion as structures of equal mass and are arranged at 90° so that the direction of the resultant inertial force of the compression mechanism and the expansion mechanism remains unchanged during the motion process or in the middle. At the same time, a recessed area is provided on the cam shaft, so that the weight of the cam shaft provided by the present invention is reduced compared with the cam shaft in the prior art, thereby reducing the centrifugal force of the cam shaft during the motion process. The design method is that the recessed area is provided in the direction of the angular bisector of the axis of the compression mechanism and the axis of the expansion mechanism to balance the inertial force of the compression mechanism and the expansion mechanism during the motion process or in the middle, thereby reducing the dynamic imbalance state of the Stirling refrigerator provided by the present invention during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic structural diagram of a compression mechanism and an expansion mechanism provided in an embodiment of the present invention;

[0023] Figure 2 for Figure 1 Side view of

[0024] Figure 3 A schematic diagram of the motion analysis of a compression mechanism provided by an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the combined inertial force state of the compression mechanism and the expansion mechanism provided in an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of the cam shaft structure provided by an embodiment of the present invention.

[0027] Among them, 10 is a compression mechanism, 110 is a compression connecting rod assembly, 120 is a first connecting pin, 130 is a compression plunger, 20 is an expansion mechanism, 210 is an expansion connecting rod assembly, 220 is a second connecting pin, 230 is an expansion plunger, 30 is a cam shaft, 310 is a recessed area, 3110 is a recessed portion, 320 is a shaft body, and 330 is a sleeve. DETAILED DESCRIPTION

[0028] The core of the present invention is to disclose a Stirling refrigerator so that the refrigerator operates in a dynamic equilibrium state.

[0029] To help those skilled in the art better understand the present invention, embodiments of the present invention are described below with reference to the accompanying drawings. The embodiments described below do not limit the scope of the invention as set forth in the claims. Furthermore, the entire contents of the embodiments described below are not intended to be limiting as necessary to address the invention as set forth in the claims.

[0030] like Figure 1 and Figure 2As shown, the Stirling refrigerator provided by the embodiment of the present invention includes a compression mechanism 10, an expansion mechanism 20 and a cam shaft 30, wherein the compression mechanism 10 includes a compression connecting rod assembly 110, and the compression connecting rod assembly 110 is used to drive other components in the compression mechanism 10 to cooperate with the compression cylinder to perform piston movement through rotational motion. Similarly, the expansion mechanism 20 includes an expansion connecting rod assembly 210, and the expansion connecting rod assembly 210 is used to drive other components in the expansion mechanism 20 to cooperate with the expansion cylinder to perform piston movement through rotational motion, thereby achieving refrigeration. In particular, in the Stirling refrigerator provided by the embodiment of the present invention, the design masses of the compression mechanism 10 and the expansion mechanism 20 are equal, and since the inertia force of a moving object is only related to the weight, the inertia forces of the compression mechanism 10 and the expansion mechanism 20 are balanced during the movement.

[0031] The cam shaft 30 is driven by a motor to rotate, and at the same time, the compression connecting rod assembly 110 and the expansion connecting rod assembly 210 are sleeved on the outer periphery of the cam shaft 30 so as to be driven to rotate under the rotation of the cam shaft 30. The compression connecting rod assembly 110 and the expansion connecting rod assembly 210 are arranged on the cam shaft 30 in such a way that the axial projection of the compression connecting rod assembly 110 and the expansion connecting rod assembly 210 on the cam shaft 30 is maintained at 90°. It should be noted that the piston motion mode of the compression mechanism 10 and the expansion mechanism 20 is alternating motion. It should be noted here that the piston motion includes the top dead center and the bottom dead center, and the mechanism for the piston motion is between the top dead center and the bottom dead center, that is, a piston The alternating motion of the compression mechanism 10 and the expansion mechanism 20 here specifically refers to that when the compression mechanism 10 moves to its top dead center position or bottom dead center position during the piston movement, the expansion mechanism 20 moves to the midpoint position of the piston stroke, and when the expansion mechanism 20 moves to its top dead center position or bottom dead center position during the piston movement, the compression mechanism 10 moves to the midpoint position of the piston stroke, thereby making the direction of the resultant inertial force of the compression mechanism 10 and the expansion mechanism 20, which have the same mass and a positional relationship of 90°, always consistent during the movement, that is, along the direction of the angular bisector of the axis of the compression mechanism 10 and the axis of the expansion mechanism 20.

[0032] In order to clearly illustrate the resultant force state of the inertial force acting on the compression mechanism 10 and the expansion mechanism 20 provided in the embodiment of the present invention during the movement, a specific embodiment of the present invention is now described. Figure 3 and Figure 4As shown, in this embodiment, the compression mechanism 10 is in a vertical state, the expansion mechanism 20 is in a horizontal state, and the compression mechanism 10 moves to the top dead center position and the midpoint of the piston stroke, and moves toward the midpoint of the piston stroke. Correspondingly, the expansion mechanism 20 moves to between the midpoint of the piston stroke and the top dead center position, and moves toward the top dead center position. Since the speed of the mechanism is 0 when it is at the top and bottom dead centers and reaches the maximum speed when it is at the midpoint of the piston stroke, when acceleration occurs, the inertial force will make the object tend to maintain its original state of motion. Therefore, the compression mechanism 10 accelerates toward the midpoint of the piston stroke, and the inertial force on the compression mechanism 10, that is, F A Similarly, the expansion mechanism 20 moves toward the top dead center position to decelerate, so the inertial force of the expansion mechanism 20, ie F B The direction is horizontally to the right. A and F B The size of is analyzed as follows, taking the compression mechanism 10 as an example. Figure 3 and Figure 4 As shown:

[0033] d1=OD-OA=(L+r)-(rcosα+Lcosβ)

[0034] in:

[0035] d1 is the distance between DA, i.e., the distance of the piston stroke of the compression mechanism 10;

[0036] L is the equivalent length of the compression link assembly 110;

[0037] r is the rotation radius of the compression link assembly 110;

[0038] α and β are the two interior angles of ΔOAB.

[0039] From ΔEOB and ΔEAB, we know that

[0040] EB=Lsinβ=rsinα,

[0041] make Then we have:

[0042] sinβ=λsinα,

[0043]

[0044] therefore:

[0045]

[0046] The acceleration of the compression mechanism 10 during the piston stroke can be calculated as follows:

[0047]

[0048] Right now

[0049] in:

[0050] a A is the acceleration of the compression mechanism 10 during the piston stroke movement;

[0051] v is the movement speed of the compression mechanism 10 during the piston stroke movement;

[0052] w A is the angular velocity of the compression connecting rod assembly 110 during rotation;

[0053] therefore:

[0054]

[0055] Since both λ and cos2α are less than 0, ignoring the second-order cosine, we can obtain:

[0056] a A =rw A 2 cosα,

[0057] Similarly, the acceleration of the expansion mechanism 20, which is perpendicular to the compression mechanism 10 at an angle of 90°, is:

[0058] a B =rw B 2 sinα,

[0059] in:

[0060] a B is the acceleration of the compression mechanism 10 during the piston stroke movement;

[0061] w B is the angular velocity of the compression connecting rod assembly 110 during rotation;

[0062] From the above process, we can get:

[0063] The inertial force F generated by the compression mechanism 10 at this position A for:

[0064] F A =m A a A =m A w A 2 rcosα

[0065] in:

[0066] m Ais the mass of the compression mechanism 10;

[0067] The inertial force F generated by the expansion mechanism 20 at this position B for:

[0068] F B =m B a B =m B w B 2 rsinα

[0069] in:

[0070] m B is the mass of the expansion mechanism 20;

[0071] Therefore, in this state, the inertial force F of the compression mechanism 10 and the expansion mechanism 20 is 合 for:

[0072]

[0073] In the embodiment of the present invention, the compression mechanism 10 and the expansion mechanism 20 are designed to have the same mass, that is:

[0074] m A =m B ,

[0075] The compression link assembly 110 and the expansion link assembly 210 rotate at the same angle within the same period, that is:

[0076] w A =w B ,

[0077] therefore:

[0078] F 合 =m A w A 2 r=m B w B 2 r,

[0079] The inertial force F of the compression mechanism 10 and the expansion mechanism 20 with the same mass and a 90° position relationship during the movement is 合 The direction is always consistent, that is, along the angular bisector of the axis of the compression mechanism 10 and the axis of the expansion mechanism 20.

[0080] It should be noted that the direction of the resultant inertial force of the compression mechanism 10 and the expansion mechanism 20 at other positions can be derived according to the above process, which will not be repeated here.

[0081] In the above embodiment, the magnitude and direction of the resultant inertial force of the compression mechanism 10 and the expansion mechanism 20 have been described, and the resultant inertial force of the compression mechanism 10 and the expansion mechanism 20 is precisely the reason why the Stirling refrigerator produces dynamic imbalance problems during operation. Therefore, on the basis of this embodiment, the cam shaft 30 includes a recessed area 310, and the recessed area 310 is arranged in the direction of the angular bisector of the axis of the compression mechanism 10 and the axis of the expansion mechanism 20. The setting of the recessed area 310 is essentially to dig out the complete configuration of the shaft in the prior art. At the same time, the setting of the recessed area 310 can reduce the centrifugal force of the cam shaft 30 in the embodiment of the present invention in the direction of the angular bisector of the axis of the compression mechanism 10 and the axis of the expansion mechanism 20 during rotation. By reducing the centrifugal force, the resultant inertial force of the compression mechanism 10 and the expansion mechanism 20 is partially offset and balanced, thereby reducing the dynamic imbalance state during the operation of the refrigerator.

[0082] The Stirling refrigerator provided by an embodiment of the present invention designs the compression mechanism 10 and the expansion mechanism 20 that perform alternate piston motion as structures of equal mass and are arranged at 90° so that the direction of the resultant inertial force of the compression mechanism 10 and the expansion mechanism 20 remains unchanged during the motion process or in the middle. At the same time, a recessed area 310 is provided on the cam shaft 30, so that the cam shaft 30 provided by the present invention is lighter than the cam shaft 30 in the prior art, thereby reducing the centrifugal force of the cam shaft 30 during the motion process. The design method is that the recessed area 310 is provided in the direction of the angular bisector of the axis of the compression mechanism 10 and the axis of the expansion mechanism 20 to balance the inertial force of the compression mechanism 10 and the expansion mechanism 20 during the motion process or in the middle, thereby reducing the dynamic imbalance state of the Stirling refrigerator provided by the present invention during operation, and improving the dynamic balance performance of the Stirling refrigerator by reducing material, which also saves production costs and installation convenience.

[0083] Furthermore, in a specific embodiment of the present invention, the cam shaft 30 includes a cylindrical shaft body 320 and a sleeve 330 sleeved on the outer circumference of the shaft body 320. The recessed area 310 is an arc-shaped recess starting from the first end face of the sleeve 330 and extending toward the second end face of the sleeve 330. The arc-shaped recess can make the recessed area 310 extend toward the angular bisector of the axis of the compression mechanism 10 and the axis of the expansion mechanism 20, thereby ensuring that the reduction of centrifugal force can smoothly offset the combined inertia force of the compression mechanism 10 and the expansion mechanism 20. At the same time, the sleeve 330 is made of a regular cylinder formed by the first end face and the second end face as the two end faces without the recessed area 310, that is, the sleeve 330 of the wheel shaft in the prior art is a regular cylindrical configuration. The cam shaft 30 provided in the embodiment of the present invention is a sleeve 330 of the wheel shaft in the prior art, in which the recessed area 310 is removed to reduce the mass of the cam shaft 30 and achieve the purpose of reducing the centrifugal force during the rotation process of the cam shaft 30.

[0084] In order to further optimize the above technical solution, the inertial force generated by the axis of the compression mechanism 10 and the expansion mechanism 20 during the movement process is completely offset so that the Stirling refrigerator is in a dynamic equilibrium state. In a specific embodiment of the present invention, the mass reduction Δm of the concave area 310 is accurately calculated. It can be seen from the above embodiment that the inertial force F of the compression mechanism 10 and the expansion mechanism 20 is 合 for:

[0085] F 合 =m A w A 2 r=m B w B 2 r,

[0086] The centrifugal force of the reduced mass Δm during the rotation process is:

[0087] F 离 =Δmw 2 r,

[0088] in:

[0089] w is the angular velocity of the cam shaft 30 during rotation;

[0090] Since the rotation process of the cam shaft 30, the compression mechanism 10 and the expansion mechanism 20 is synchronously driven, the rotation angle relationship of the rotation process is equal, that is:

[0091] w=w A ,

[0092] Therefore, when the value of Δm is equal to m A or m B When they are equal, F 离 =F 合 At this time, the centrifugal force reduced by the excavated recessed area 310 and the inertial force generated by the movement of the axis of the compression mechanism 10 and the expansion mechanism 20 are offset by each other, and the Stirling refrigerator is in a dynamic equilibrium state.

[0093] Furthermore, the recessed area 310 can be provided as a whole or in parts, in order to ensure the balance of torque during the rotation of the shaft, such as Figure 5 As shown, in a specific embodiment of the present invention, the recessed area 310 includes two recessed portions 3110, and the two recessed portions 3110 are symmetrically arranged on the two end surfaces of the sleeve 330. The symmetrically arranged recessed portions 3110 can balance the axial force of the cam shaft 30 during rotation.

[0094] Furthermore, the compression link assembly 110 and the expansion link assembly 210 are sleeved on the outer periphery of the sleeve 330. At the same time, the distance between the compression link assembly 110 and the first end face is equal to the distance between the expansion link assembly 210 and the second end face, that is, the compression link assembly 110 and the expansion link assembly 210 are also arranged on the outer periphery of the sleeve 330, at two positions symmetrical about the bisecting plane of the side wall of the sleeve 330, further improving the balance of the axial force on the cam shaft 30 during rotation.

[0095] On the basis of the above embodiment, in the compression mechanism 10, the compression connecting rod assembly 110 is transmission-connected to the compression plunger 130 through the first connecting pin 120, the compression plunger 130 extends into the compression cylinder, and the compression connecting rod assembly 110 is connected to the compression plunger 130 through the first connecting pin 120 to convert the rotational motion of the compression connecting rod assembly 110 into the linear reciprocating motion of the compression plunger 130, thereby enabling the compression plunger 130 to perform compression motion in the compression cylinder to perform the refrigeration work of the Stirling refrigerator.

[0096] Correspondingly, in the expansion mechanism 20, the expansion link assembly 210 is transmission-connected to the expansion plunger 230 through the second connecting pin 220, the expansion plunger 230 extends into the expansion cylinder, and the expansion link assembly 210 is connected to the expansion plunger 230 through the second connecting pin 220 to convert the rotational motion of the expansion link assembly 210 into the linear reciprocating motion of the expansion plunger 230, thereby causing the expansion plunger 230 to perform expansion motion in the expansion cylinder to perform the refrigeration work of the Stirling refrigerator.

[0097] Furthermore, the compression link assembly 110 and the expansion link assembly 210 are sleeved on the outer periphery of the cam shaft 30 through bearings to achieve transmission connection with the cam shaft 30.

[0098] The terms "first," "second," "left," and "right," etc., in the specification and claims of the present invention and the accompanying drawings are used to distinguish between different objects, not to describe a specific order. Furthermore, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements and may include steps or elements that are not listed.

[0099] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A Stirling refrigerator, characterized in that: include: A compression mechanism (10) and an expansion mechanism (20) of equal mass, wherein the compression mechanism (10) comprises a compression connecting rod assembly (110), and when the compression connecting rod assembly (110) rotates, the compression mechanism (10) cooperates with the compression cylinder to perform piston motion, and the expansion mechanism (20) comprises an expansion connecting rod assembly (210), and when the expansion connecting rod assembly (210) rotates, the expansion mechanism (20) cooperates with the expansion cylinder to perform piston motion; The cam shaft (30) is driven to rotate by a motor, the compression connecting rod assembly (110) and the expansion connecting rod assembly (210) are sleeved on the cam shaft (30) and are transmission-connected to the cam shaft (30), and the axial projection angle of the compression connecting rod assembly (110) and the expansion connecting rod assembly (210) on the cam shaft (30) is maintained at 90°; The cam shaft (30) includes a recessed area (310), and the recessed area (310) is arranged in the direction of extension of the angular bisector of the axis of the compression mechanism (10) and the axis of the expansion mechanism (20).

2. The Stirling refrigerator according to claim 1, wherein The cam shaft (30) comprises a shaft body (320) and a sleeve (330) sleeved on the outer periphery of the shaft body (320); the recessed area (310) is an arc-shaped recess extending from a first end face of the sleeve (330) toward a second end face of the sleeve (330); and the sleeve (330) is made by hollowing out the recessed area (310) from a regular cylinder formed by the first end face and the second end face as two end faces.

3. The Stirling refrigerator according to claim 2, wherein: The sleeve (330) is made by hollowing out a region of the regular cylinder that is equivalent to the mass of the expansion mechanism (20).

4. The Stirling refrigerator according to claim 2, wherein: The recessed area (310) includes two recessed portions (3110), and the two recessed portions (3110) are symmetrically arranged on both end surfaces of the sleeve (330).

5. The Stirling refrigerator according to claim 4, wherein: The compression connecting rod assembly (110) and the expansion connecting rod assembly (210) are sleeved on the outer circumference of the sleeve (330), and the distance between the compression connecting rod assembly (110) and the first end face is equal to the distance between the expansion connecting rod assembly (210) and the second end face.

6. The Stirling refrigerator according to claim 1, wherein: In the compression mechanism (10), the compression connecting rod assembly (110) is transmission-connected to a compression plunger (130) via a first connecting pin (120), and the compression plunger (130) extends into the compression cylinder; In the expansion mechanism (20), the expansion connecting rod assembly (210) is transmission-connected to the expansion plunger (230) via a second connecting pin (220), and the expansion plunger (230) extends into the expansion cylinder.

7. The Stirling refrigerator according to claim 1, wherein The compression connecting rod assembly (110) and the expansion connecting rod assembly (210) are sleeved on the outer periphery of the cam shaft (30) via bearings.

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