turbomolecular pump

Abstract

The support structure (200) for the rotor shaft (140) of the turbomolecular pump (100) comprises a central section (200a, 300a, 400a, 500a) for coupling to the rotor shaft of the turbomolecular pump, the central section having a center point through which the axis of rotation of the rotor shaft passes when the rotor shaft is coupled to the central section, and legs (200b, 300b, 400b, 500b) extending from the central section, the legs for coupling the central section to a housing of the turbomolecular pump, the legs extending tangentially to the central section.

Description

[Technical Field]

[0001] The present invention relates to a turbomolecular pump. [Background technology]

[0002] A turbomolecular pump is a type of pump that operates by using rotating blades in one or more bladed pump stages to force gas molecules in a desired pumping direction. Summary of the Invention [Means for solving the problem]

[0003] In one aspect, a support structure for a rotor shaft of a turbomolecular pump is provided, the support structure comprising: a central section for coupling to the rotor shaft of the turbomolecular pump, the central section having a center point through which an axis of rotation of the rotor shaft passes when the rotor shaft is coupled to the central section; and legs extending from the central section, the legs for coupling the central section to a housing of the turbomolecular pump, the legs extending tangentially to the central section.

[0004] The center section may be integrally formed with the legs.

[0005] The central section may have a circular profile.

[0006] The legs may include a substantially straight section and a curved section.

[0007] The legs may be generally curved.

[0008] The support structure may include a plurality of legs evenly angularly spaced about the central section, each of the plurality of legs extending from the central section, each of the plurality of legs for connecting the central section to a housing of the turbomolecular pump, and each of the plurality of legs extending tangentially to the central section.

[0009] The support structure may further comprise an additional strip of material joining one of the plurality of legs to another of the plurality of legs.

[0010] The support structure may comprise just three legs.

[0011] The tangential extension of the legs relative to the center section can act to transfer rotational forces exerted on the center section towards the legs.

[0012] In another aspect, an apparatus for a turbomolecular pump is provided, comprising a housing for the turbomolecular pump and a support structure of the above aspect.

[0013] The support structure may be integrally formed with the housing.

[0014] The legs may extend between the housing and the center section to couple the center section to the housing.

[0015] The housing may include an opening defining an inlet to the turbomolecular pump, the support structure being disposed in the opening.

[0016] The rotor shaft may be coupled to the center section by a bearing, preferably a permanent magnetic bearing.

[0017] In yet another aspect, there is provided a turbomolecular pump including the support structure of the above aspect or the device of the above aspect.

[0018] In yet another aspect, there is provided a use of a turbomolecular pump of the above aspect for pumping a gas. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 shows a schematic diagram of a turbomolecular pump (not to scale). [Figure 2A] FIG. 1 shows a perspective view (not necessarily to scale) of a rotor support structure of a turbomolecular pump. [Figure 2B] FIG. 1 shows a top view of a rotor support structure of a turbomolecular pump (not necessarily to scale). [Figure 3] FIG. 1 shows a perspective view (not necessarily to scale) of another rotor support structure that can be used in a turbomolecular pump. [Figure 4] FIG. 10 shows a perspective view (not necessarily to scale) of yet another rotor support structure that can be used in a turbomolecular pump. [Figure 5] FIG. 10 shows a perspective view (not necessarily to scale) of yet another rotor support structure that can be used in a turbomolecular pump. DETAILED DESCRIPTION OF THE INVENTION

[0020] FIG. 1 is a schematic diagram (not to scale) illustrating a turbomolecular pump 100. The turbomolecular pump 100 includes an inlet 105, a housing 110, a plurality of stator blades 120, a plurality of rotor blades 130, a rotor shaft 140, and a rotor support structure 200. The turbomolecular pump 100 is configured to receive gas at the inlet 105 and use rotation of the rotor blades 130 relative to the stator blades 120 to force the received gas through an outlet (not shown). The physical mechanisms used by turbomolecular pumps to pump gas are well understood and will not be described in detail here. However, briefly, the rotor blades 130 are angled relative to the stator blades 20 such that rotation of the rotor blades 130 forces gas through the spaces between the rotor and stator blades 120, 130 in a desired pumping direction, pumping the gas through the turbomolecular pump 100. The direction of travel of the pumped gas through the turbomolecular pump 100 is indicated by dashed arrows in FIG. 1.

[0021] The housing 110 defines a substantially cylindrical space within which the stator blades 120, rotor blades 130, rotor shaft 140, and rotor support structure 200 are disposed. The inlet 105 is defined by an opening in the housing 110 at an end of the substantially cylindrical space defined by the housing 110. The stator blades 120 are stationary within the housing 110. The rotor blades 130 are attached to the rotor shaft 140 such that rotation of the rotor shaft 140 rotates the rotor blades 130 about a central longitudinal axis of the rotor shaft 140. The rotor shaft 140 is coupled to and supported by the rotor support structure 200. The rotor support structure 200 is attached to the housing 110 and is positioned to hold the rotor shaft 140 in place within the housing 110. Various different configurations / shapes of the rotor support structure 200 are described below.

[0022] 2A and 2B show perspective and top views of a rotor support structure 200 according to one embodiment. The rotor support structure 200 includes a central section 200a and a plurality of legs 200b extending from the central section 200a. In this embodiment, the rotor support structure 200 includes three legs 200b. In this embodiment, the central section 200a has a circular profile. The central section 200a is coupled to the shaft 140 (the shaft 140 is not fully shown in FIG. 2A ) so that the shaft 140 can rotate relative to the central section 200a. The central section 200a includes a bearing (not shown) to facilitate rotation of the rotor shaft 140 relative to the central section 200a. Thus, the central section 200a may be referred to as a bearing hub. Each of the plurality of legs 200b extends from the central section 200a to a position on the housing 110. The central section 200 a and the plurality of legs 200 b are disposed in an opening that defines the inlet 105 .

[0023] Each of the plurality of legs 200b includes a substantially linear extension section 200b-1 and a curved section 200b-2. The substantially linear extension section 200b-1 is attached to the central section 200a via the curved section 200b-2. The substantially linear extension section 200b-1 has a longitudinal central axis (shown by a dotted line in FIGS. 2A and 2B ) offset from the center point of the central section 200a. The center point of the central section 200a is the point through which the rotational axis of the rotor shaft 140 extends. Thus, the central longitudinal axis of the substantially linear extension section 200b-1 is perpendicular to the rotational axis of the rotor shaft 140 and is radially offset from the rotational axis of the rotor shaft 140. In this embodiment, the offset between the central longitudinal axis of the substantially linear extension section 200b-1 and the rotational axis of the rotor shaft 140 is approximately 6 mm. This offset means that each of the legs 200b extends tangentially relative to the central section 200a. In other words, the legs 200b do not extend perpendicularly from the central section 200a. In general, it should be understood that the exact offset distance is not limited to 6mm, and that any offset distance that enables the functionality described herein can be used.

[0024] In this embodiment, the legs 200b are evenly angularly spaced about the central section 200a. In this embodiment, the substantially linear extension section 200b-1 and the curved section 200b-2 of each of the legs 200b are integrally formed with one another. In this embodiment, each of the legs 200b is integrally formed with the central section 200a. Also, in this embodiment, each of the legs 200b is integrally formed with the housing 110.

[0025] In the event that rotation of the rotor shaft 140 imparts a rotational force to the center section 200a, for example, if the rotor shaft sticks or breaks during operation of the turbomolecular pump 100, the above-described tangential extension and offset of the legs 200b help transfer the force along the legs 200b as a compressive force rather than as a shear force across the legs 200b. This is indicated by the arrows in FIG. 2B. Thus, the legs 200b are less likely to break or be damaged compared to a design without the offset, because a compressive force pushing against the legs 200b is less likely to damage the legs 200b than a shear force across them.

[0026] FIG. 3 is a diagram (not necessarily to scale) illustrating a perspective view of another rotor support structure 300 usable with the turbomolecular pump 100, according to one embodiment. The rotor support structure 300 includes a central section 300a and a plurality of legs 300b. Each of the plurality of legs 300b includes a substantially straight extension section 300b-1 and a curved section 300b-2. The rotor support structure 300 illustrated in FIG. 3 is the same as the rotor support structure 200 illustrated in FIGS. 2A and 2B, except that the curved section 300b-2 is thicker. This embodiment tends to result in greater overall stiffness for the rotor support structure 300. As with the embodiment of FIGS. 2A and 2B, in this embodiment, each of the legs 300b extends tangentially to the central section 300a.

[0027] Figure 4 is a diagram (not necessarily to scale) showing a perspective view of yet another rotor support structure 400 that can be used with turbomolecular pump 100. Rotor support structure 400 includes a central section 400a and a plurality of legs 400b. Rotor support structure 400 shown in Figure 4 is similar to rotor support structure 200 shown in Figures 2A and 2B, except that each of legs 400b is generally curved. As with the embodiment of Figures 2A and 2B, in this embodiment, the curvature of legs 400b means that legs 400b do not extend perpendicularly from the central section; instead, each of legs 400b can be considered to extend tangentially to central section 400a.

[0028] FIG. 5 is a perspective view (not necessarily to scale) of yet another rotor support structure 500 usable with the turbomolecular pump 100. The rotor support structure 500 includes a central section 500a and a plurality of legs 500b. Each of the legs 500b includes a substantially linear extension section 500b-1 and a curved section 500b-2. The rotor support structure 500 shown in FIG. 5 is the same as the rotor support structure 200 shown in FIGS. 2A and 2B, except that the curved sections 500b-2 of the legs 500b are connected by additional strips of material 500c. In this embodiment, each strip 500c is curved and extends between two adjacent curved sections 500b-2 around the periphery of the central section 500a. The presence of the strips 500c tends to provide greater overall stiffness for the rotor support structure 500, similar to the embodiment of FIG. 3. Similar to the embodiment of Figures 2A and 2B, in this embodiment, each of the legs 500b extends tangentially to the central section 500a.

[0029] 3-5, each of the legs 300b, 400b, 500b extends from the central section 300a, 400a, 500a, such that rotational forces acting on the central section 300a, 400a, 500a tend to be transmitted as compressive forces toward the legs 300b, 400b, 500b. Thus, similar to the embodiment of FIGS. 2A and 2B, the rotor support structures 300, 400, 500 of the embodiments of FIGS. 3-5 are less likely to break or be damaged if the rotor shaft 140 sticks or fails during operation.

[0030] In this manner, a rotor support structure for a turbomolecular pump is provided. The rotor support structure described above advantageously tends to improve resistance to rotational forces without significantly blocking the inlet of the turbomolecular pump. Advantageously, the use of three legs tends to provide a good balance between using fewer components to prevent inlet blockage and providing sufficient rigidity to the rotor support structure. Advantageously, forming the legs integrally with the housing means that the connection points between each of the legs and the housing tend to be inflexible, so all rotational forces are transmitted through the legs, thereby providing a rigid structure without blocking the inlet of the turbomolecular pump. Furthermore, the rotor support structure described above advantageously reduces tolerance stackup within the pump because fewer parts have to be affected by misalignment relative to the center section.

[0031] In the above embodiment, the rotor support structure comprises three legs, however, in other embodiments a different number of legs are used, for example 1, 2, 4, 5, etc.

[0032] In the above embodiment, the central section of the rotor support structure has a circular profile, however, in other embodiments, profiles of various shapes, for example triangular or elliptical, can be used.

[0033] In the above embodiments, the legs extend tangentially from the central section and / or are offset from the center point of the central section on the sides of the central section so that the rotational force compresses the legs. However, in other embodiments, the legs extend tangentially from the central section and / or are offset from the center point of the central section on the sides of the central section so that the rotational force applies tension to the legs. For example, in one such embodiment, the turbomolecular pump is the same as that described with reference to Figures 2A and 2B, except that each of the legs is offset from the center point on an opposite side of the central section. In these embodiments, the legs can be formed from a ductile material.

[0034] It will be understood that various modifications / variations can be made to the above-described embodiments without departing from the scope of the present invention. [Explanation of symbols]

[0035] 100 Turbomolecular Pump 105 Entrance 110 Housing 120 stator blades 130 rotor blades 140 rotor shaft 200 Rotor support structure 200a, 300a, 400a, 500a central section 200b, 300b, 400b, 500b Legs 200b-1, 300b-1, 500b-1 extension section 200b-2, 300b-2, 500b-2 curved sections 500c strip

Claims

1. 1. A support structure for a rotor shaft of a turbomolecular pump, comprising: a central section for coupling to the rotor shaft of the turbomolecular pump, the central section having a center point through which an axis of rotation of the rotor shaft passes when the rotor shaft is coupled to the central section; legs extending from the central section, the legs for connecting the central section to a housing of the turbomolecular pump; Equipped with The legs extend tangentially to the central section.

2. The support structure of claim 1 , wherein the central section is integrally formed with the legs.

3. 3. The support structure of claim 1 or 2, wherein the central section has a circular profile.

4. A support structure according to any one of claims 1 to 3, wherein the legs comprise substantially straight sections and curved sections.

5. A support structure according to any one of claims 1 to 3, wherein the legs are generally curved.

6. 6. The support structure of claim 1, wherein the support structure comprises a plurality of legs arranged at equal angular intervals around the central section, each of the plurality of legs extending from the central section, each of the plurality of legs for connecting the central section to a housing of the turbomolecular pump, and each of the plurality of legs extending tangentially to the central section.

7. The support structure of claim 6 , further comprising an additional strip of material joining one of the plurality of legs to another of the plurality of legs.

8. A support structure according to any one of claims 1 to 7, wherein the support structure comprises exactly three legs.

9. 9. A support structure as claimed in any one of claims 1 to 8, wherein the tangential extension of the legs relative to the central section acts to transmit rotational forces acting on the central section towards the legs.

10. 1. An apparatus for a turbomolecular pump, comprising: a housing for the turbomolecular pump; A support structure according to any one of claims 1 to 9; An apparatus comprising:

11. The apparatus of claim 9 , wherein the support structure is integrally formed with the housing.

12. 11. The device of claim 9 or 10, wherein the legs extend between the housing and the central section to couple the central section to the housing.

13. 12. Apparatus according to any one of claims 9 to 11, wherein the housing includes an opening defining an inlet for the turbomolecular pump, and the support structure is disposed in the opening.

14. A turbomolecular pump comprising a support structure according to any one of claims 1 to 9 or an apparatus according to any one of claims 10 to 13.

15. Use of a turbomolecular pump according to claim 14 for pumping gas.

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