Low-temperature vacuum pump refrigerating machine

Abstract

The low-temperature vacuum pump refrigerating machine comprises a power motor and a box body, the power motor comprises a power driving shaft, the power motor is connected to the box body, the power driving shaft extends into the box body, a reverse connecting thread is arranged at the end of the power driving shaft, and the reverse connecting thread and the power motor are arranged in the direction opposite to the rotating direction. A cam shaft assembly is arranged in the box body and comprises an eccentric shaft body, a reducing shaft sleeve, a first bearing and a second bearing, the eccentric shaft body is in threaded connection with a reverse connecting thread of the power driving shaft, the eccentric shaft body is provided with a first bearing part and a second bearing part in the axial direction, and the first bearing is arranged on the first bearing part; the variable-diameter shaft sleeve is arranged on the second bearing part, and the second bearing is arranged on the variable-diameter shaft sleeve. Therefore, the refrigerating machine adopts a brand-new cam group shaft combined structure, so that the manufacturing cost is reduced, the structural strength is improved, and the service life is prolonged.

Description

A cryogenic vacuum pump refrigerator Technical Field

[0001] This invention relates to the field of cryogenic pump technology, and in particular to cryogenic vacuum pump refrigeration machines. Background Technology

[0002] A cryogenic vacuum pump is a device that uses cryogenic condensation and adsorption to capture gas molecules to achieve a high vacuum environment. High-sealing, large-diameter cryogenic vacuum pumps are widely used in semiconductor manufacturing, aerospace simulation, high-energy physics research and other fields due to their unique ability to handle large gas volumes. Its core structure includes a pump casing, a primary cold head and an outer radiation baffle, a secondary cold head and an outer condensation array. The cryogenic condensation array is cooled to an extremely low temperature below 20K by a refrigerant (such as liquid nitrogen, liquid helium or GM refrigerator), thereby condensing and capturing gas molecules.

[0003] Cryogenic pumps typically employ a two-stage cold head, operating according to the Gifford-McMahon principle. In the two cold heads connected in series, the temperature of helium is reduced to approximately 80 K in the first pump stage and further reduced to approximately 20 K in the second pump stage. Cryogenic vacuum pumps usually employ a radiation baffle structure, installed inside the pump casing inlet and internal space, to block external thermal radiation from entering the cryogenic region of the pump casing, while simultaneously intercepting gas molecules to improve condensation efficiency. A common arrangement of radiation baffles is a dense arrangement along the gas inlet path, aiming to completely cover the cross-section of the upper side of the pump casing's inner wall. This layout effectively blocks thermal radiation and condenses and captures a large amount of high-boiling-point gas. During this process, the cryostat, driven by a motor, uses a cam in conjunction with a control valve to control the entry and exit of helium, while simultaneously causing a drive rod to push a piston in reciprocating motion within the cylinder to obtain cooling.

[0004] Traditional motor drive structures typically use key or screw connections. However, due to the need for eccentric bearings for intake and exhaust valve control, existing camshafts employ a two-component assembly: component A for the intake camshaft and component B for the exhaust camshaft. In use, bearings are usually assembled onto components A and B respectively, and then the two components are pinned together. This not only places high demands on the manufacturing precision of components A and B, resulting in high manufacturing costs, but also creates long, thin-walled structures that are weak and prone to deformation, leading to adverse effects. Furthermore, to prevent misalignment between the camshaft and the motor drive shaft, a key-pin structure is usually required, further increasing the structural complexity of the camshaft. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a cryogenic vacuum pump refrigerator that adopts a novel cam shaft assembly structure, thereby reducing manufacturing costs while improving structural strength and extending service life.

[0006] A cryogenic vacuum pump refrigerator according to an embodiment of the present invention includes: a power motor, the power motor including a power drive shaft; a housing, the power motor connected to the housing, and the power drive shaft extending into the housing, the end of the power drive shaft having a reverse connecting thread, the reverse connecting thread being arranged opposite to the rotation direction of the power motor, the housing having a camshaft assembly, the camshaft assembly including an eccentric shaft, a variable diameter bushing, a first bearing, and a second bearing, the eccentric shaft being screwed onto the reverse connecting thread of the power drive shaft, the eccentric shaft having a first bearing portion and a second bearing portion along the axial direction, the first bearing being disposed on the first bearing portion, the variable diameter bushing being disposed on the second bearing portion, and the second bearing being disposed on the variable diameter bushing.

[0007] According to some embodiments of the present invention, the camshaft assembly further includes: a limiting end plate, the limiting end plate being sleeved on the eccentric shaft and abutting against the side of the second bearing portion away from the first bearing portion.

[0008] According to some embodiments of the present invention, the camshaft assembly further includes a spacing shim, the spacing shim being sleeved between the first bearing and the second bearing.

[0009] According to some embodiments of the present invention, the variable diameter bushing has a flange on the end near the first bearing portion.

[0010] According to some embodiments of the present invention, the device further includes an air inlet pipe and an air outlet pipe, wherein the bottom of the housing is provided with an air distribution base, the air inlet pipe is disposed on the air distribution base, the air outlet pipe is disposed on the power motor housing, and a vent is provided between the power motor and the housing.

[0011] According to some embodiments of the present invention, the gas distribution base is provided with a gas distribution control assembly, the gas distribution control assembly includes a base and a rocker unit, one end of the rocker unit is hinged to the base, and the other end is used to abut against the punch of the control valve, the rocker unit includes a U-shaped adjusting plate, an adjusting roller and an adjusting rod, the U-shaped adjusting plate is provided with an adjusting slide in the middle, the adjusting roller is embedded in the adjusting slide, and one end of the adjusting rod passes through the side wall of the U-shaped adjusting plate and is connected to the adjusting roller.

[0012] In some embodiments of the present invention, the adjusting rod is a screw, and the adjusting roller is threadedly connected to the adjusting rod.

[0013] According to some embodiments of the present invention, the housing is provided with a viewing window.

[0014] Beneficial effects

[0015] This invention utilizes a variable-diameter bushing to alter the diameter of one side of the second bearing of the eccentric shaft. This allows the first bearing to be assembled from the second bearing side, enabling the eccentric shaft to form a single, integral structure. This allows for increased thickness of the eccentric shaft, effectively enhancing its structural strength. Furthermore, the reverse-threaded connection between the eccentric shaft and the drive shaft simplifies the connection structure, eliminating the need for key pins on the eccentric shaft. This not only reduces processing costs and precision, lowering overall production costs, but also prevents thinning of the eccentric shaft, effectively ensuring its structural strength. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which: FIG1 is a schematic diagram of the overall structure of a refrigerator according to an embodiment of the present invention; FIG2 is a schematic diagram of the cross-sectional structure of a refrigerator according to an embodiment of the present invention; FIG3 is a schematic diagram of the structure of a camshaft assembly according to an embodiment of the present invention; FIG4 is a schematic diagram of the separate assembly of an eccentric shaft and a power drive shaft according to an embodiment of the present invention; FIG5 is a schematic diagram of the cooperation between a camshaft assembly and a valve train control assembly according to an embodiment of the present invention; FIG6 is a schematic diagram of the structure of a valve train control assembly according to an embodiment of the present invention.

[0017] Reference numerals: 100, Refrigeration unit; 1, Power motor; 11, Power drive shaft; 12, Reverse connection thread; 2, Housing; 21, Viewing window; 22, Gas distribution base; 3, Camshaft assembly; 31, Variable diameter bushing; 32, First bearing; 33, Second bearing; 34, Limiting end plate; 35, Spacing shim; 4, Eccentric shaft; 41, First bearing section; 42, Second bearing section; 51, Inlet pipe; 52, Outlet pipe; 6, Gas distribution control assembly; 61, Base; 62, Rocker unit; 621, U-shaped adjusting plate; 622, Adjusting roller; 623, Adjusting rod; 624, Adjusting slide. Detailed Implementation

[0018] The technical solutions of the embodiments disclosed in this application will be clearly and completely described below with reference to the accompanying drawings. The descriptions of the embodiments are merely illustrative and exemplary, and are not intended to limit the scope of this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort should fall within the scope of protection of this disclosure. Furthermore, techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification.

[0019] Referring to Figures 1 to 6, a cryogenic vacuum pump refrigerator according to an embodiment of the present invention includes: a power motor 1 and a housing 2. The power motor 1 is connected to the housing 2, and a power drive shaft 11 extends into the housing 2. The power motor 1 includes a power drive shaft 11, and the end of the power drive shaft 11 is provided with a reverse connection thread 12, the rotation direction of which is opposite to the rotation direction of the power motor 1. A camshaft assembly 3 is provided inside the housing 2. The camshaft assembly 3 includes an eccentric shaft 4, a variable diameter bushing 31, a first bearing 32, and a second bearing 33. During assembly, the eccentric shaft 4 is screwed onto the reverse connection thread 12 of the power drive shaft 11, which facilitates the increasingly tight connection of the eccentric shaft 4 as the power drive shaft 11 rotates.

[0020] The eccentric shaft 4 is provided with a first bearing part 41 and a second bearing part 42 along the axial direction. The first bearing 32 is provided on the first bearing part 41, and the variable diameter bushing 31 is provided on the second bearing part 42, so that the second bearing 33 can be provided on the variable diameter bushing 31.

[0021] In use, due to the presence of the variable diameter bushing 31, the outer diameter of the second bearing portion 42 is smaller than that of the first bearing 32. This makes it easier to first assemble the first bearing 32 and the second bearing 33 side onto the first bearing portion 41 of the eccentric shaft 4. The size of the first bearing portion 41 can be the same as the inner diameter of the first bearing 32. Then, the variable diameter bushing 31, which has the same inner diameter as the second bearing 33, is assembled onto the second bearing portion 42. Finally, the second bearing 33 is installed onto the variable diameter bushing 31.

[0022] In order to facilitate the assembly of the off-center bearing, the traditional camshaft assembly 3 is designed as a two-component structure. On this basis, in order to facilitate the transmission of torque, a key pin structure is also required between the camshaft assembly 3 and the electrode output shaft. This requires further coupling of the key pin structure on the basis of the two-component plug-in structure, which makes the structure very complex and the manufacturing cost high. Moreover, in order to facilitate plug-in, the structure of both components is relatively thin, which affects the strength of the components.

[0023] This application uses a variable diameter bushing 31 to change the diameter of one side of the second bearing 33 of the eccentric shaft 4, which facilitates the assembly of the first bearing 32 from the second bearing 33 side. This allows the eccentric shaft 4 to form an integral structure and serve as the base of the entire camshaft assembly 3. All structures, including the variable diameter bushing 31, are connected to the eccentric shaft 4. Compared with the traditional plug-in thin-walled camshaft assembly 3, this allows for the thickening of the eccentric shaft 4 without affecting the assembly of the inlet and outlet bearings, effectively improving the structural strength of the shaft and avoiding any negative impacts.

[0024] Meanwhile, the eccentric shaft 4 and the power drive shaft 11 are connected by a reverse thread, which simplifies the connection structure between the drive shaft and the eccentric shaft 4. Compared with the traditional plug-in thin-walled camshaft assembly 3, there is no need to design a key pin structure on the separately assembled assembly, which helps to reduce processing costs and processing accuracy, thereby facilitating the reduction of the structure's production cost.

[0025] Therefore, this application simplifies the structure of the camshaft assembly 3 and reduces the production cost of the structure by combining the reverse thread structure and the variable diameter bushing 31. It also simplifies the connection structure of the camshaft assembly 3 with the power drive shaft 11.

[0026] Preferably, based on the above embodiment, the variable diameter bushing has a flange on the end near the first bearing portion. The flange is used to limit the axial displacement of the second bearing and the axial displacement of the first bearing, while isolating the first bearing and the second bearing to avoid interference.

[0027] Furthermore, based on the above embodiments, as shown in FIG3, the camshaft assembly 3 also includes a limiting end plate 34. The limiting end plate 34 is sleeved on the eccentric shaft 4 and abuts against the side of the second bearing portion 42 away from the first bearing portion 41, thereby limiting the axial displacement of the variable diameter bushing 31 and limiting the axial displacement of the second bearing 33, thereby improving the reliability of the refrigerator operation.

[0028] Preferably, based on the above embodiments, as shown in FIG3, the camshaft assembly 3 further includes a spacing shim 35. The spacing shim 35 is annular and made of rubber. The spacing shim 35 is sleeved between the first bearing 32 and the second bearing 33. The thickness of the spacing shim 35 can better control the distance between the first bearing 32 and the second bearing 33, thereby improving the assembly accuracy. At the same time, it avoids rigid contact between the variable diameter bushing and the stepped sidewall of the eccentric shaft, reducing the probability of abnormal noise.

[0029] In some embodiments of the present invention, as shown in Figures 1 and 2, the cryogenic vacuum pump refrigeration unit further includes an inlet pipe 51 and an outlet pipe 52. The bottom of the housing 2 is provided with a gas distribution base, wherein the inlet pipe 51 is provided on the gas distribution base, the outlet pipe 52 is provided on the housing of the power motor 1, and a vent is provided between the power motor 1 and the housing 2.

[0030] In use, one end of the inlet pipe 51 is connected to the gas distribution base, and one end of the outlet pipe 52 is connected to the housing of the power motor 1. The other ends of both the inlet pipe 51 and the outlet pipe 52 are connected to the compressor. The working medium of the compressor is gaseous helium, which is compressed in the compressor and then expanded in the cold head, allowing it to absorb external heat. After the gaseous helium undergoes the Gifford-McMahon refrigeration cycle in the cold head, its temperature will rise to more than ten degrees Celsius when it leaves the cold head. At this time, the helium gas at this temperature is introduced from the housing into the power motor 1 and then returned to the compressor. The low-temperature helium gas can carry away some of the heat from the power motor 1, thereby achieving the cooling effect of the power motor 1.

[0031] In some embodiments of the present invention, as shown in FIG6, an air distribution control component 6 is provided on the air distribution base 22. The air distribution control component 6 includes a base 61 and a rocker unit 62. One end of the rocker unit 62 is hinged to the base 61, and the other end is used to abut against the punch of the air distribution valve in the air distribution base 22. Specifically, the rocker unit 62 includes a U-shaped adjusting plate 621, an adjusting roller 622, and an adjusting rod 623. The middle of the U-shaped adjusting plate 621 is hollow, and an inclined slope is provided near the opening of the U-shaped adjusting plate 621 to form a V-shaped adjusting slide 624. The adjusting roller 622 is embedded in the V-shaped adjusting slide 624, and one end of the adjusting rod 623 passes through the side wall of the U-shaped adjusting plate 621 and is connected to the adjusting roller 622.

[0032] In use, the adjusting rod 623 can be used to control the adjusting roller 622 to move back and forth along its axis. At this time, the opening degree of the U-shaped adjusting plate 621 can be adjusted by adjusting the roller 622, which is conducive to more precise control of the opening degree and opening time of the inlet and outlet valves.

[0033] Preferably, based on the above embodiments, the adjusting rod 623 is a screw, and the adjusting roller 622 is threadedly connected to the adjusting rod 623. In this way, the adjusting roller 622 can be moved back and forth more conveniently by rotating the adjusting rod 623. The adjustment structure is simpler, which helps to reduce the difficulty of adjustment operation. Moreover, the screw can be a standard part, which is cheaper and helps to reduce production costs.

[0034] In some embodiments of the present invention, the housing 2 is provided with a viewing window 21. The working status of the components inside the housing 2 can be observed more intuitively through the viewing window 21, which facilitates timely understanding and discovery of the fault point when a fault occurs, thereby improving maintenance efficiency.

[0035] In the description of this invention, it should be understood that if terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0036] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0037] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A cryogenic vacuum pump refrigerator, characterized in that, include: A power motor, comprising a power drive shaft; a housing, wherein the power motor is connected to the housing, and the power drive shaft extends into the housing, the end of the power drive shaft is provided with a reverse connection thread, the reverse connection thread being arranged opposite to the rotation direction of the power motor; a camshaft assembly is provided in the housing, the camshaft assembly comprising an eccentric shaft, a variable diameter bushing, a first bearing, and a second bearing, the eccentric shaft being screwed onto the reverse connection thread of the power drive shaft, the eccentric shaft being provided with a first bearing portion and a second bearing portion along the axial direction, the first bearing being disposed on the first bearing portion, the variable diameter bushing being disposed on the second bearing portion, and the second bearing being disposed on the variable diameter bushing.

2. The cryogenic vacuum pump refrigerator according to claim 1, characterized in that, The camshaft assembly further includes a limiting end plate, which is sleeved on the eccentric shaft and abuts against the side of the second bearing portion away from the first bearing portion.

3. A cryogenic vacuum pump refrigerator according to claim 1 or 2, characterized in that, The camshaft assembly further includes a spacing shim, which is sleeved between the first bearing and the second bearing.

4. A cryogenic vacuum pump refrigerator according to claim 3, characterized in that, The variable diameter bushing has a flange on the end near the first bearing portion.

5. A cryogenic vacuum pump refrigerator according to claim 1 or 4, characterized in that, It also includes an air inlet pipe and an air outlet pipe. The bottom of the housing is provided with an air distribution base. The air inlet pipe is located on the air distribution base. The air outlet pipe is located on the motor housing. A vent is provided between the motor and the housing.

6. A cryogenic vacuum pump refrigerator according to claim 5, characterized in that, The gas distribution base is equipped with a gas distribution control component, which includes a base and a rocker unit. One end of the rocker unit is hinged to the base, and the other end is used to abut against the punch of the control valve. The rocker unit includes a U-shaped adjusting plate, an adjusting roller, and an adjusting rod. The U-shaped adjusting plate has an adjusting slide in the middle, and the adjusting roller is embedded in the adjusting slide. One end of the adjusting rod passes through the side wall of the U-shaped adjusting plate and is connected to the adjusting roller.

7. A cryogenic vacuum pump refrigerator according to claim 1, characterized in that, The adjusting rod is a screw, and the adjusting roller is threadedly connected to the adjusting rod.

8. A cryogenic vacuum pump refrigerator according to claim 1, characterized in that, The box is equipped with a viewing window.

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