Stirling cryocooler and drive mechanism therefor

Abstract

The present application relates to a kind of stirling refrigerators and its driving mechanism, the driving mechanism includes driving motor and transmission shaft system, transmission shaft system includes first transmission shaft and second transmission shaft, first transmission shaft is coaxially connected with the motor rotor of driving motor, second transmission shaft is equipped with the transmission output part for driving connection with the movement component of refrigerator;The axis of second transmission shaft is perpendicular to the axis of first transmission shaft, second transmission shaft is connected between first transmission shaft by rotary transmission pair, rotary transmission pair is used to convert the rotary motion of first transmission shaft into the rotary motion of second transmission shaft.The present application will be set as the first transmission shaft and second transmission shaft of transmission shaft system, by the vertical intersection axis arrangement mode of two transmission shafts, the overall axial length of transmission shaft system can be significantly shortened, make the structure of refrigerator more compact, can better adapt to the application occasion of limited installation space, facilitate to realize the application mode of stirling refrigerator, hand-held, vehicle-mounted, airborne etc..

Description

Technical Field

[0001] This invention belongs to the field of Stirling refrigerator technology, specifically relating to a drive mechanism for a Stirling refrigerator and a Stirling refrigerator equipped with the drive mechanism. Background Technology

[0002] Stirling refrigerators are widely used in infrared night vision, missile guidance, and cryogenic medical applications due to their advantages of rapid cooling, high efficiency, and wide cooling temperature range. Rotary Stirling refrigerators, in particular, are suitable for space- and weight-sensitive applications such as handheld, vehicle-mounted, and airborne applications due to their small size, light weight, and compact structure.

[0003] When a rotary Stirling refrigerator is running, the drive control system drives the rotor assembly to rotate. The rotor assembly is fixedly connected to the central drive shaft (i.e., the main shaft). An eccentric mechanism on the main shaft converts the rotational motion into the reciprocating motion of a piston, creating a refrigeration effect. However, the existing technology has the following problems:

[0004] (1) The spindle is a long shaft, which makes centering and installation difficult and requires high precision in the machining and installation of parts;

[0005] (2) The spindle is a slender shaft, which limits its application scenarios when the installation space is limited;

[0006] (3) The speed adjustment of the refrigerator can only be achieved by continuously increasing power consumption, which limits its use in power-sensitive scenarios such as handheld devices. Summary of the Invention

[0007] The present invention relates to a drive mechanism for a Stirling refrigerator and a Stirling refrigerator equipped with the drive mechanism, which can at least solve some of the defects of the prior art.

[0008] This invention relates to a drive mechanism for a Stirling refrigerator, comprising a drive motor and a transmission shaft system. The transmission shaft system includes a first transmission shaft and a second transmission shaft. The first transmission shaft is coaxially connected to the motor rotor of the drive motor. The second transmission shaft is provided with a transmission output section for driving connection with a moving part of the refrigerator. The axis of the second transmission shaft is perpendicular to the axis of the first transmission shaft. The second transmission shaft and the first transmission shaft are connected by a rotary transmission pair, which is used to convert the rotational motion of the first transmission shaft into the rotational motion of the second transmission shaft.

[0009] As one embodiment, the rotary transmission pair is a rolling friction pair, including a driving wheel coaxially fixed on the first transmission shaft and a driven wheel coaxially fixed on the second transmission shaft. The rim of the driving wheel presses against the disk surface of the driven wheel, and the pressing position is offset from the axis of the second transmission shaft.

[0010] As one implementation method, the rim of the active wheel is provided with a rounded chamfer between the wheel rim and the disk surface.

[0011] As one embodiment, the transmission shaft system further includes a speed regulating structure for adjusting the transmission ratio between the first transmission shaft and the second transmission shaft.

[0012] As one embodiment, the speed regulating structure includes an axial drive unit capable of driving the first transmission shaft to move axially.

[0013] As one embodiment, the axial drive unit includes a drive solenoid valve, which includes an electromagnetic drive component and a mechanical extension rod arranged parallel to the axis of the first transmission shaft. The extension length of the mechanical extension rod is adjusted by energizing or de-energizing the electromagnetic drive component. The mechanical extension rod acts on the bearing portion on the first transmission shaft.

[0014] As one embodiment, the output end of the axial drive unit contacts the bearing portion on the first transmission shaft, and the speed regulating structure further includes an axial reset unit, which is used to provide a reset force to the first transmission shaft, and the direction of the reset force is opposite to the direction of the force of the axial drive unit.

[0015] As one implementation method, the relative position between the stator and rotor of the drive motor satisfies the following: the stator can generate a continuous axial static magnetic force on the rotor; the first drive shaft is also equipped with an axial limiting unit to resist the axial static magnetic force so as to keep the first drive shaft in a predetermined axial position.

[0016] As one embodiment, the drive mechanism further includes a motor housing and a base. The drive motor and the first transmission shaft are both disposed inside the motor housing, and the second transmission shaft is at least partially housed inside the base. The motor housing is mounted on the base, and the mounting surface is an annular mating surface with the inner ring coaxial with the second transmission shaft.

[0017] The present invention also relates to a Stirling refrigerator equipped with the drive mechanism described above.

[0018] The present invention has at least the following beneficial effects:

[0019] This invention sets the transmission shaft system as a separate first transmission shaft and second transmission shaft. By arranging the two transmission shafts in a perpendicular cross-axis manner, the overall axial length of the transmission shaft system can be significantly shortened, making the overall structure of the refrigeration unit more compact. This allows it to better adapt to applications with limited installation space and facilitates the implementation of handheld, vehicle-mounted, and airborne applications of the Stirling refrigeration unit. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the drive mechanism provided in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of the first drive shaft;

[0023] Figure 3 This is a schematic diagram of the second drive shaft;

[0024] Figure 4 This is a schematic diagram of the assembly structure of the motor housing and the base. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] like Figures 1-3 This invention provides a drive mechanism for a Stirling refrigerator, including a drive motor and a transmission shaft system. The transmission shaft system includes a first transmission shaft 20 and a second transmission shaft 30. The first transmission shaft 20 is coaxially connected to the motor rotor 11 of the drive motor. The second transmission shaft 30 is provided with a transmission output part 34 for driving connection with the moving parts of the refrigerator. The axis of the second transmission shaft 30 is perpendicular to the axis of the first transmission shaft 20. The second transmission shaft 30 and the first transmission shaft 20 are connected by a rotary transmission pair, which is used to convert the rotational motion of the first transmission shaft 20 into the rotational motion of the second transmission shaft 30.

[0028] The aforementioned drive motor includes a motor rotor 11 and a motor stator 12. The motor rotor 11 and the first transmission shaft 20 are fixedly connected by means including but not limited to interference fit, key connection, and bonding, so that the first transmission shaft 20 rotates synchronously when the motor rotor 11 rotates.

[0029] The transmission output section 34 on the second transmission shaft 30 can be an eccentric shaft section, a crank structure, etc., used to convert rotary motion into reciprocating linear motion of moving parts. The moving parts of the refrigeration unit can be a compression piston, a push piston, etc.

[0030] In this embodiment, the transmission shaft system is set as a separate first transmission shaft 20 and second transmission shaft 30. By arranging the two transmission shafts in a perpendicular cross-axis manner, the overall axial length of the transmission shaft system can be significantly shortened, which can better adapt to applications with limited axial installation space and facilitate the implementation of handheld, vehicle-mounted, and airborne applications of Stirling refrigerators.

[0031] The aforementioned rotary friction pair can be a bevel gear pair, a worm gear mechanism, etc. As a preferred embodiment, such as... Figure 1 The rotary transmission pair is a rolling friction pair, including a driving wheel 21 coaxially fixed on the first transmission shaft 20 and a driven wheel 31 coaxially fixed on the second transmission shaft 30. The rim of the driving wheel 21 presses against the disk surface of the driven wheel 31 and the pressing position is offset from the axis of the second transmission shaft 30.

[0032] The driving wheel 21 can be a disc-shaped end integrally formed with the first drive shaft 20, or it can be a separate disc-shaped part fixedly mounted on the first drive shaft 20. Similarly, the driven wheel 31 can be a disc-shaped end integrally formed with the second drive shaft 30, or it can be a separate disc-shaped part fixedly mounted on the second drive shaft 30.

[0033] The contact point between the driving wheel 21 and the driven wheel 31 is offset from the axis of the second drive shaft 30; that is, the contact point between the driving wheel 21 and the driven wheel 31 is not located on the axis of the second drive shaft 30. When the driving wheel 21 rotates with the first drive shaft 20, the driven wheel 31 is driven to rotate around the axis of the second drive shaft 30 by the friction between the rim of the driving wheel and the surface of the driven wheel. Since the contact point of the driving wheel 21 is offset from the axis of the second drive shaft 30, the rotational motion of the driving wheel 21 can generate a torque around the axis of the second drive shaft 30, thereby driving the second drive shaft 30 to rotate.

[0034] In order to generate sufficient friction between the driving wheel 21 and the driven wheel 31 to transmit torque, a certain preload needs to be applied between them. This preload can be guaranteed by the installation position accuracy of the first drive shaft 20 and the second drive shaft 30.

[0035] Compared with gear transmission, the above-mentioned rolling friction pair structure has the advantages of simple structure and high tolerance to installation errors. It also requires no lubrication or only a small amount of lubrication, making it more suitable for the sealed working environment of Stirling refrigeration machines.

[0036] Furthermore, such as Figure 1 and Figure 2 The driving wheel 21 has a rounded chamfer between its rim and the disk surface. Specifically, a rounded transition surface is provided at the intersection of the driving wheel 21's surface (the surface in contact with the driven wheel 31's disk surface) and the disk surface. Preferably, the driving wheel 21 has rounded chamfers between its rim and both disk surfaces. By providing the rounded chamfers, even if there are small dimensional deviations in the perpendicular intersection of the first drive shaft 20 and the second drive shaft 30 (e.g., axis offset or angular deviation due to machining or assembly errors), the driving wheel 21 and the driven wheel 31 can still maintain a stable contact state, avoiding contact failure or stress concentration. This design significantly reduces the precision requirements for parts machining and the difficulty of assembling the entire machine.

[0037] More preferably, the transmission shaft system further includes a speed regulating structure for adjusting the transmission ratio between the first transmission shaft 20 and the second transmission shaft 30. This speed regulating structure can change the speed ratio between the first transmission shaft 20 and the second transmission shaft 30 without changing the input power of the drive motor, thereby realizing the adjustment of the cooling capacity of the refrigeration mechanism.

[0038] In one embodiment, the speed regulation structure includes an axial drive unit capable of driving the first drive shaft 20 to move axially. When the first drive shaft 20 moves axially, the position of the driving wheel 21 relative to the driven wheel 31 changes, and the radial distance between the contact point of the driving wheel rim and the driven wheel surface relative to the axis of the second drive shaft 30 changes accordingly. The transmission ratio between the first drive shaft 20 and the second drive shaft 30 also changes accordingly. By continuously changing the axial position of the first drive shaft 20, stepless adjustment of the transmission ratio can be achieved. The speed regulation structure provided in this embodiment does not require continuous increase in power consumption and is suitable for power-sensitive applications such as handheld devices.

[0039] Miniature hydraulic cylinders, miniature pneumatic cylinders, and other linear drive devices are all suitable as the aforementioned axial drive unit. As a preferred embodiment, the axial drive unit includes a drive solenoid valve 23, which comprises an electromagnetic drive component and a mechanical extension rod arranged parallel to the axis of the first transmission shaft 20. The extension length of the mechanical extension rod is adjusted by energizing or de-energizing the electromagnetic drive component. The mechanical extension rod acts on the bearing portion of the first transmission shaft 20.

[0040] Preferably, the mechanical extension rod can be a ring rod, or multiple mechanical extension rods arranged around the axis of the first drive shaft 20; the aforementioned electromagnetic drive is preferably a ring electromagnetic drive, and more preferably arranged coaxially with the first drive shaft 20, including but not limited to being arranged around the mechanical extension rod. When the overall machine operating speed is detected to be too high, the external control system provides a pulse current to energize or de-energize the drive solenoid valve 23 (when energized, the electromagnetic drive drives the mechanical extension rod to move; after the mechanical extension rod has moved to its position, the electromagnetic drive is de-energized), thereby adjusting the extension length of the mechanical extension rod, and thus adjusting the axial position of the first drive shaft 20 to achieve the purpose of speed regulation.

[0041] The aforementioned bearing portion is positioned appropriately on the first drive shaft 20 to bear the driving force of the mechanical extension rod. For example, it can be the outer ring of a motor bearing 22 mounted on the first drive shaft 20, or a shoulder, boss, or other structure provided on the body of the first drive shaft 20. In the case where the motor bearing 22 is mounted on the first drive shaft 20, the motor bearing 22 needs to be able to move axially. Therefore, such as... Figure 1 The motor bearing 22 should be movably mounted in a cavity of the motor housing 41, and its outer ring is preferably in radial clearance fit with the inner wall of the cavity, which can improve the reliability of the axial movement of the motor bearing 22.

[0042] The output end of the axial drive unit can be fixedly connected to the bearing portion on the first transmission shaft 20, allowing the axial drive unit to directly drive the first transmission shaft 20 to perform axial reciprocating motion. In another embodiment, the output end of the axial drive unit contacts the bearing portion on the first transmission shaft 20, but the two are not fixedly connected. In this case, the speed regulating structure further includes an axial reset unit, which provides a reset force to the first transmission shaft 20. The direction of the reset force is opposite to the direction of the force of the axial drive unit. During operation, the axial drive unit provides a driving force in a first direction (e.g., to the left), pushing the first transmission shaft 20 to move along the first direction. The axial reset unit provides a reset force in a second direction (e.g., to the right). This reset force can be generated when the driving force of the axial drive unit disappears or when it is necessary for the first transmission shaft 20 to move along the second direction, or it can be a continuous force (e.g., the elastic force provided by a spring). When the driving force of the axial drive unit decreases or disappears, the reset force pushes the first transmission shaft 20 to reset.

[0043] In one embodiment, the relative position between the motor stator 12 and the motor rotor 11 of the drive motor satisfies the following: the motor stator 12 can generate a continuous axial static magnetic force on the motor rotor 11; the first drive shaft 20 is also provided with an axial limiting unit to resist the axial static magnetic force so as to keep the first drive shaft 20 in a predetermined axial position.

[0044] Preferably, such as Figure 1 The motor stator 12 and the motor rotor 11 are not perfectly aligned at their ends in the axial direction, but rather there is a predetermined axial offset. Since the magnetic lines of force between the motor stator 12 and the motor rotor 11 always tend to close along the shortest path, when there is an axial offset, an axial static magnetic force is generated that tends to center the two in the axial direction.

[0045] When the first drive shaft 20 moves to contact the axial limiting unit under the action of axial static magnetic force, the axial limiting unit provides a reverse constraint force, which balances the axial static magnetic force, thereby stably holding the first drive shaft 20 in a predetermined position. Based on the above design, the positional stability of the first drive shaft 20 can be effectively improved, eliminating axial movement or positional drift that may be caused by factors such as vibration and impact, and ensuring the positional stability of the transmission pair and the consistency of the transmission ratio.

[0046] In particular, when the coupling design incorporates the aforementioned stator 12-rotor 11 mating structure (generating axial static magnetic force) and the aforementioned speed regulating structure, this axial static magnetic force can be used as the aforementioned reset force, and the stator 12-rotor 11 mating structure constitutes the aforementioned axial reset unit. This solution utilizes the motor's own structure to generate the reset force, eliminating the need for additional reset components such as springs, simplifying the structure, saving installation space, and, since the static magnetic force is a non-contact force, eliminating wear issues, thus offering advantages of high reliability and long lifespan. Correspondingly, the aforementioned axial drive unit can be configured as the aforementioned axial limiting unit.

[0047] Further optimize the aforementioned drive mechanism, such as Figure 1 and Figure 4 The drive mechanism further includes a motor housing 41 and a base 42. The drive motor and the first transmission shaft 20 are both disposed in the motor housing 41, and the second transmission shaft 30 is at least partially housed in the base 42. The motor housing 41 is mounted on the base 42, and the mounting surface is an annular mating surface with the inner ring coaxial with the second transmission shaft 30.

[0048] The motor stator 12 can be fixedly mounted on the inner wall of the motor housing 41, including but not limited to bonding, interference fit, or screw connection; the first drive shaft 20 can be rotatably supported within the motor housing 41 via bearing 22. In the case of an axial drive unit, this axial drive unit can also be housed within the motor housing 41. The second drive shaft 30 can be rotatably mounted in the base 42 via bottom bearing 32, drive bearing 33, etc.; Figure 1 The second drive shaft 30 is preferably partially located inside the base 42 and partially extended into the motor housing 41 to cooperate with the first drive shaft 20.

[0049] The motor housing 41 and the base 42 are connected by, but not limited to, a flange connection structure 43. Since the inner ring of the mounting mating surface is coaxial with the second drive shaft 30, the spatial relative position relationship (i.e., the perpendicular intersection of the axes) between the first drive shaft 20 inside the motor housing 41 and the second drive shaft 30 inside the base 42 remains unchanged no matter what angle the motor housing 41 rotates to. Therefore, the motor housing 41 can be installed on the base 42 at any circumferential angle without affecting the internal transmission fit, which greatly improves the installation adaptability of the whole machine in the upper-level equipment.

[0050] Example 2

[0051] This invention provides a Stirling refrigerator equipped with the drive mechanism provided in Embodiment 1 above.

[0052] The Stirling refrigerator is preferably a rotary Stirling refrigerator, whose moving parts are driven and connected to the transmission output part 34 of the second transmission shaft 30 (which can be connected through transmission components 5 such as connecting rods), converting the rotational motion of the second transmission shaft 30 into the reciprocating linear motion of the piston to realize the refrigeration cycle.

[0053] Due to the adoption of the above-mentioned drive mechanism, the Stirling refrigerator provided in this embodiment has the advantages of small overall size, low assembly precision requirements, low power consumption stepless speed regulation, and good installation adaptability. It is particularly suitable for applications that are sensitive to space and power consumption, such as handheld devices, vehicle-mounted devices, and airborne devices.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drive mechanism for a Stirling cryocooler comprising a drive motor and a drive train, characterised in that, The transmission shaft system includes a first transmission shaft and a second transmission shaft. The first transmission shaft is coaxially connected to the motor rotor of the drive motor. The second transmission shaft is provided with a transmission output part for driving connection with the moving parts of the refrigerator. The axis of the second transmission shaft is perpendicular to the axis of the first transmission shaft. The second transmission shaft and the first transmission shaft are connected by a rotary transmission pair, which is used to convert the rotational motion of the first transmission shaft into the rotational motion of the second transmission shaft.

2. The drive mechanism of claim 1, wherein: The rotary transmission pair is a rolling friction pair, including a driving wheel coaxially fixed on the first transmission shaft and a driven wheel coaxially fixed on the second transmission shaft. The rim of the driving wheel presses against the disk surface of the driven wheel, and the pressing position is offset from the axis of the second transmission shaft.

3. The drive mechanism of claim 2, wherein: The rim of the active wheel has a rounded chamfer between it and the surface.

4. The drive mechanism of claim 2, wherein: The transmission shaft system also includes a speed regulating structure for adjusting the transmission ratio between the first transmission shaft and the second transmission shaft.

5. The drive mechanism of claim 4, wherein: The speed regulating structure includes an axial drive unit capable of driving the first transmission shaft to move axially.

6. The drive mechanism of claim 5, wherein: The axial drive unit includes a drive solenoid valve, which includes an electromagnetic drive component and a mechanical extension rod arranged parallel to the axis of the first transmission shaft. The extension length of the mechanical extension rod is adjusted by energizing or de-energizing the electromagnetic drive component. The mechanical extension rod acts on the bearing portion of the first transmission shaft.

7. The drive mechanism of claim 5, wherein: The output end of the axial drive unit contacts the bearing portion on the first transmission shaft. The speed regulation structure also includes an axial reset unit, which provides a reset force to the first transmission shaft. The direction of the reset force is opposite to the direction of the force of the axial drive unit.

8. The drive mechanism according to any one of claims 1 to 7, characterized in that, The relative positions between the stator and rotor of the drive motor satisfy the following conditions: the stator can generate a continuous axial static magnetic force on the rotor; the first drive shaft is also equipped with an axial limiting unit to resist the axial static magnetic force and keep the first drive shaft in a predetermined axial position.

9. The drive mechanism of claim 1, wherein: It also includes a motor housing and a base. The drive motor and the first transmission shaft are both disposed inside the motor housing, and the second transmission shaft is at least partially housed inside the base. The motor housing is mounted on the base, and the mounting surface is an annular mating surface with the inner ring coaxial with the second transmission shaft.

10. A Stirling cryocooler characterised in that, It is equipped with a drive mechanism as described in any one of claims 1 to 9.

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