Main shaft and impeller connecting structure and magnetic suspension molecular pump

Abstract

The utility model discloses a main shaft and impeller connecting structure and magnetic suspension molecular pump. Main shaft and impeller connecting structure include: main shaft, impeller, tablet and a plurality of fastener, and the upper end surface of main shaft is provided with first recess; Impeller includes impeller main part and a plurality of dynamic sheet, and the upper end surface of impeller main part is provided with second recess, and the lower end surface of impeller main part is provided with third recess, and the connecting portion is formed between second recess and third recess, and the tablet is placed at the bottom wall of second recess, and the top wall of third recess is protruded with the convex part in the middle portion downward, and the convex part is assembled in first recess through the temperature difference assembly method, and the upper end surface of main shaft is attached in the top wall of third recess, and the fastener passes through tablet, connecting portion and is locked in the upper end of main shaft, and the tablet is clamped between the head of fastener and the bottom wall of second recess. The utility model can guarantee basic rigidity, prevent the relative displacement between main shaft and impeller, guarantee the centring and the connecting strength under the high -speed rotation.

Description

Technical Field

[0001] This utility model relates to the field of magnetic levitation molecular pump technology, and in particular to a main shaft and impeller connection structure and a magnetic levitation molecular pump. Background Technology

[0002] As a high-end vacuum device, the core components of a magnetic levitation molecular pump include a high-speed rotating rotor and a precisely controlled magnetic levitation system. The impeller with moving vanes is the key element for the molecular pump to transfer the momentum of gas molecules. It is usually fixed on the rotor shaft and requires extremely high rotational accuracy, dynamic balance, and structural stability.

[0003] Existing spindle and impeller connection structures mostly use screw fastening, tapered surface fit, or interference fit, which have the following disadvantages:

[0004] 1. The magnetic levitation molecular pump rotates at a much higher speed than the traditional molecular pump. The heat generated after high-speed rotation causes changes in the modes at the internal connections, affecting the stability of the system.

[0005] 2. High assembly complexity: requires high-precision positioning and multiple adjustments.

[0006] 3. Insufficient reliability: It is prone to loosening or slight displacement under high-speed operation, which affects the rotor balance.

[0007] Therefore, it is necessary to propose an optimized connection structure between the main shaft and the impeller to solve at least some of the aforementioned technical problems. Utility Model Content

[0008] The purpose of this invention is to provide a main shaft and impeller connection structure and a magnetic levitation molecular pump, which can solve at least one of the technical problems mentioned in the background art.

[0009] To achieve the above objectives, this utility model provides a main shaft and impeller connection structure for a magnetically levitated molecular pump. The main shaft and impeller connection structure includes: a main shaft, an impeller, a pressure plate, and several fasteners. A first groove is formed in the middle of the upper end face of the main shaft. The impeller includes an impeller body and several moving plates disposed on the outside of the impeller body. A second groove is formed in the middle of the upper end face of the impeller body, and a third groove is formed in the middle of the lower end face of the impeller body. A connecting portion is formed between the second groove and the third groove. The pressure plate is placed on the bottom wall of the second groove. A protrusion extends downward from the middle of the top wall of the third groove. The protrusion is interference-fitted into the first groove by a temperature difference assembly method. The upper end face of the main shaft is attached to the top wall of the third groove. The fasteners pass through the pressure plate and the connecting portion and are locked to the upper end of the main shaft. The pressure plate is clamped between the head of the fastener and the bottom wall of the second groove.

[0010] Optionally, the pressure plate has a first central through hole located at the center and a plurality of first bolt through holes arranged around the first central through hole; the connecting part has a second central through hole corresponding to the first central through hole and extending vertically through the center, the second central through hole extending downward through the protrusion, and the connecting part also has a plurality of second bolt through holes arranged around the second central through hole and the protrusion; the upper end face of the main shaft has a plurality of threaded holes, and the plurality of threaded holes, the plurality of first bolt through holes and the plurality of second bolt through holes are arranged in a one-to-one correspondence; the fastener includes bolts, and the plurality of bolts pass through the corresponding first bolt through holes and the second bolt through holes respectively and are fixedly connected to the corresponding threaded holes.

[0011] Optionally, the first groove and the protrusion are cylindrical.

[0012] Optionally, when the protrusion is interference-fitted into the first groove using a temperature difference assembly method, the protrusion is in a cooled state and the spindle is in a heated state.

[0013] Optionally, the coefficient of thermal expansion of the impeller body is greater than that of the main shaft.

[0014] Optionally, the main shaft is made of 40Cr steel, and the impeller body is made of aluminum alloy.

[0015] Optionally, the upper end of the spindle is formed with a flange portion, which fits against the top wall of the third groove.

[0016] Optionally, a ring of counterweight holes is formed around the periphery of the pressure plate, surrounding the plurality of first bolt through holes, and the counterweight holes are used to place counterweight nails.

[0017] Optionally, several of the moving plates and the impeller body are integrally formed.

[0018] To achieve the above objectives, this utility model also provides a magnetic levitation molecular pump, including the main shaft and impeller connection structure as described above.

[0019] In this embodiment of the invention, a protrusion extends downward from the center of the top wall of the third groove. The protrusion is interference-fitted into the first groove of the main shaft using a temperature difference assembly method, and the upper end face of the main shaft is in contact with the top wall of the third groove. A pressure plate is placed on the bottom wall of the second groove. Fasteners pass through the pressure plate and the connecting part and are locked to the upper end of the main shaft. The pressure plate is clamped between the head of the fastener and the bottom wall of the second groove. Because the protrusion is interference-fitted into the first groove using a temperature difference assembly method, the basic rigidity can be guaranteed, the relative displacement between the main shaft and the impeller can be prevented, and the alignment and connection strength under high-speed rotation can be guaranteed. Combined with the fit between the fastener, pressure plate, connecting part and main shaft, the assembly reliability between the main shaft and the impeller can be effectively improved. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of the magnetic levitation molecular pump component in an embodiment of this utility model.

[0021] Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure of a magnetically levitated molecular pump.

[0022] Figure 3 This is a three-dimensional structural diagram of the main shaft of an embodiment of this utility model.

[0023] Figure 4 This is a three-dimensional structural diagram of the impeller in an embodiment of the present invention.

[0024] Figure 5 This is a three-dimensional structural schematic diagram of the impeller according to another embodiment of the present invention.

[0025] Figure 6 This is a three-dimensional structural diagram of the tablet compression of this utility model embodiment. Detailed Implementation

[0026] To explain in detail the technical content, structural features, and effects of this utility model, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0027] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0028] In the description of this utility model, it should be noted that the terms "upper", "lower", "top", "bottom", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] Please see Figures 1 to 6 This utility model discloses a main shaft and impeller connection structure for a magnetic levitation molecular pump.

[0030] The main shaft and impeller connection structure includes: a main shaft 10, an impeller 20, a pressure plate 30, and several fasteners 40. A first groove 11 is formed in the middle of the upper end face of the main shaft 10. The impeller 20 includes an impeller body 21 and several moving plates 22 disposed on the outside of the impeller body 21. A second groove 211 is formed in the middle of the upper end face of the impeller body 21, and a third groove 212 is formed in the middle of the lower end face of the impeller body 21. A connecting groove is formed between the second groove 211 and the third groove 212. The connecting part 213 and the pressure plate 30 are placed on the bottom wall of the second groove 211. The middle part of the top wall of the third groove 212 protrudes downward from the protrusion 214. The protrusion 214 is interference-fitted into the first groove 11 by the temperature difference assembly method. The upper end face of the main shaft 10 is attached to the top wall of the third groove 212. The fastener 40 passes through the pressure plate 30 and the connecting part 213 and is locked to the upper end of the main shaft 10. The pressure plate 30 is clamped between the head 41 of the fastener 40 and the bottom wall of the second groove 211.

[0031] In this embodiment of the invention, a protrusion 214 protrudes downward from the middle of the top wall of the third groove 212. The protrusion 214 is interference-fitted into the first groove 11 of the main shaft 10 by a temperature difference assembly method, and the upper end face of the main shaft 10 is in contact with the top wall of the third groove 212. A pressure plate 30 is placed on the bottom wall of the second groove 211. A fastener 40 passes through the pressure plate 30 and the connecting part 213 and is locked to the upper end of the main shaft 10. The pressure plate 30 is clamped between the head 41 of the fastener 40 and the bottom wall of the second groove 211. Since the protrusion 214 is interference-fitted into the first groove 11 by a temperature difference assembly method, the basic rigidity can be guaranteed, the relative displacement between the main shaft 10 and the impeller 20 can be prevented, and the alignment and connection strength under high-speed rotation can be guaranteed. Combined with the cooperation between the fastener 40, the pressure plate 30, the connecting part 213 and the main shaft 10, the assembly reliability between the main shaft 10 and the impeller 20 can be effectively improved. In addition, since the protrusion 214 is interference-fitted into the first groove 11 by the temperature difference assembly method, it helps to reduce the assembly complexity.

[0032] In some embodiments, the pressure plate 30 has a first central through hole 31 located at the center and a plurality of first bolt through holes 32 arranged around the first central through hole 31; the connecting part 213 has a second central through hole 2131 corresponding to the first central through hole 31 and passing through vertically at the center, the second central through hole 2131 passing through the protrusion 214 downward, and the connecting part 213 also has a plurality of second bolt through holes 2132 arranged around the second central through hole 2131 and the protrusion 214; the upper end face of the main shaft 10 has a plurality of threaded holes 12, and the plurality of threaded holes 12, the plurality of first bolt through holes 32 and the plurality of second bolt through holes 2132 are arranged in a one-to-one correspondence; the fastener 40 is a bolt 40, and the plurality of bolts 40 pass through the corresponding first bolt through holes 32 and second bolt through holes 2132 respectively and are fixedly connected to the corresponding threaded holes 12. Through the fastening of the plurality of bolts 40, combined with the interference fit of the protrusion 214 and the first groove 11, the reliable assembly of the impeller 20 and the main shaft 10 is achieved.

[0033] In some embodiments, the first groove 11 and the protrusion 214 are cylindrical.

[0034] In some embodiments, when the protrusion 214 is interference-fitted into the first groove 11 by the temperature difference assembly method, the protrusion 214 is in a cooled state and the spindle 10 is in a heated state. When the temperature difference is at its maximum, the protrusion 214 is quickly fitted into the first groove 11 of the heated spindle 10. After assembly, it is placed in a room temperature environment to cool naturally, and the principle of thermal expansion and contraction is used to achieve a precise interference fit.

[0035] In some embodiments, the coefficient of thermal expansion of the impeller body 21 is greater than that of the main shaft 10, which can form adaptive compensation during high-speed heating and enhance connection stability. When the rotational speed is higher and the temperature is higher, the engagement between the protrusion 214 and the first groove 11 is tighter, which is beneficial for a stable connection under high-speed and high-temperature conditions.

[0036] Specifically, the main shaft 10 is made of 40Cr steel, and the impeller body 21 is made of aluminum alloy, specifically 7075T651 aluminum alloy.

[0037] In some embodiments, a flange 13 is formed at the upper end of the main shaft 10, and the flange 13 fits against the top wall of the third groove 212. This arrangement helps to increase the connection stability between the main shaft 10 and the impeller 20. It should be noted that the main shaft 10 referred to in this utility model can be a single-piece structure or an assembled structure, that is, it can include a main shaft body, on which other structures are assembled.

[0038] In some embodiments, a ring of counterweight holes 33 is formed around the periphery of the pressure plate 30, surrounding a plurality of first bolt through holes 32. The counterweight holes 33 allow for the placement of counterweight pins in at least some of the holes as needed during use, thereby facilitating dynamic balance adjustment.

[0039] In some embodiments, the tablet 30 is made of stainless steel, specifically 304 stainless steel. However, this is not a limitation.

[0040] In some embodiments, a plurality of moving plates 22 and impeller body 21 are integrally formed.

[0041] Specifically, a number of moving vanes 22 are distributed along the circumference and axial (up and down) direction of the impeller body 21.

[0042] This utility model embodiment also discloses a magnetic levitation molecular pump, including the main shaft and impeller connection structure as described above.

[0043] In this embodiment of the invention, since the protrusion 214 is interference-fitted into the first groove 11 using a temperature difference assembly method, the basic rigidity can be guaranteed, preventing relative displacement between the main shaft 10 and the impeller 20, ensuring centering and connection strength under high-speed rotation. Combined with the fit between the fastener 40, the pressure plate 30, the connecting part 213, and the main shaft 10, the assembly reliability between the main shaft 10 and the impeller 20 can be effectively improved. In addition, since the protrusion 214 is interference-fitted into the first groove 11 using a temperature difference assembly method, it helps to reduce assembly complexity.

[0044] The above-disclosed examples are merely preferred embodiments of the present utility model, intended to facilitate understanding and implementation by those skilled in the art. They should not be construed as limiting the scope of the present utility model. Therefore, any equivalent variations made in accordance with the claims of the present utility model are still within the scope of the present utility model.

Claims

1. A main shaft and impeller connection structure for a magnetically levitated molecular pump, characterized in that, The main shaft and impeller connection structure includes: a main shaft, an impeller, a pressure plate, and several fasteners. A first groove is formed in the middle of the upper end face of the main shaft. The impeller includes an impeller body and several moving blades disposed on the outside of the impeller body. A second groove is formed in the middle of the upper end face of the impeller body, and a third groove is formed in the middle of the lower end face of the impeller body. A connecting portion is formed between the second groove and the third groove. The pressure plate is placed on the bottom wall of the second groove. A protrusion extends downward from the middle of the top wall of the third groove. The protrusion is interference-fitted into the first groove by a temperature difference assembly method. The upper end face of the main shaft is attached to the top wall of the third groove. The fasteners pass through the pressure plate and the connecting portion and are locked to the upper end of the main shaft. The pressure plate is clamped between the head of the fastener and the bottom wall of the second groove.

2. The main shaft and impeller connection structure according to claim 1, characterized in that, The pressure plate has a first central through hole located at the center and a plurality of first bolt through holes arranged around the first central through hole; the connecting part has a second central through hole corresponding to the first central through hole and extending vertically through the center, the second central through hole extending downward through the protrusion, and the connecting part also has a plurality of second bolt through holes arranged around the second central through hole and the protrusion; the upper end face of the main shaft has a plurality of threaded holes, the plurality of threaded holes, the plurality of first bolt through holes and the plurality of second bolt through holes are arranged in a one-to-one correspondence; the fastener includes bolts, the plurality of bolts passing through the corresponding first bolt through holes and second bolt through holes respectively and being fixedly connected to the corresponding threaded holes.

3. The main shaft and impeller connection structure according to claim 1, characterized in that, The first groove and the protrusion are cylindrical.

4. The main shaft and impeller connection structure according to claim 1, characterized in that, When the protrusion is interference-fitted into the first groove using a temperature difference assembly method, the protrusion is in a cooled state, while the spindle is in a heated state.

5. The main shaft and impeller connection structure according to claim 1, characterized in that, The coefficient of thermal expansion of the impeller body is greater than that of the main shaft.

6. The main shaft and impeller connection structure according to claim 5, characterized in that, The main shaft is made of 40Cr steel, and the impeller body is made of aluminum alloy.

7. The main shaft and impeller connection structure according to claim 1, characterized in that, The upper end of the main shaft has a flange portion, which is attached to the top wall of the third groove.

8. The main shaft and impeller connection structure according to claim 2, characterized in that, The pressure plate has a ring of counterweight holes surrounding the plurality of first bolt through holes, and the counterweight holes are used to place counterweight nails.

9. The main shaft and impeller connection structure according to claim 1, characterized in that, The moving plates and the impeller body are integrally formed.

10. A magnetically levitated molecular pump, characterized in that, Includes the main shaft and impeller connection structure as described in any one of claims 1 to 9.

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