Molecular pump

Abstract

A pump case (10B) of a molecular pump (1B) includes a part that attaches to a vacuum chamber (70). The attachment part includes a base part (14) having an annular axial end surface (14a), an abutting part (105) that is abutted against the vacuum chamber (70), an arm part (104) that connects the base part (14) and the abutting part (105), and fixtures (15, 16) that fix the abutting part (105) to the vacuum chamber (70). The end portion of the abutting part (105) positioned on the vacuum-chamber (70) side protrudes past the axial end surface (14a) of the base part (14) toward the vacuum-chamber (70) side, whereby the base part (14) and the arm part (104) are not in contact with the vacuum chamber (70) in the attached state.

Description

Molecular Pump

[0001] The present invention relates to a molecular pump having a rotor that rotates at high speed.

[0002] Molecular pumps are vacuum pumps for creating high vacuum conditions and are attached to various processing equipment such as semiconductor manufacturing equipment, various analytical equipment, electron microscopes, etc. Generally, molecular pumps are equipped with a pump case that houses a rotor that rotates at high speed, and are installed by fixing the pump case to the vacuum chamber with fastening members such as bolts and nuts so that an intake port provided in the pump case communicates with the internal space of the vacuum chamber of the various equipment in which the high vacuum condition is created.

[0003] Here, in a molecular pump, if a large external force is applied during operation, for example due to an earthquake or the inhalation of foreign matter, causing unintended deformation of the rotor, stator, rotary drive mechanism, etc., there is a risk that the rotor, which is rotating at high speed, will come into contact with other components such as the stator.

[0004] When the rotor rotates at high speed and comes into contact with another component, the angular momentum of the rotor is transmitted to the pump case, resulting in the generation of a torque that rotates the entire molecular pump in the same direction as the rotor. If no countermeasure is taken, this torque that rotates the entire molecular pump will be transmitted directly to the vacuum chamber to which the molecular pump is fixed, and a large impact torque will be applied to the vacuum chamber.

[0005] For the purpose of mitigating the impact torque that may occur in such an abnormal situation, for example, Japanese Patent Laid-Open Publication No. 2005-69194 (Patent Document 1) discloses a molecular pump configured so that in an abnormal situation, the flange of the pump case fixed to the vacuum chamber rotates by a predetermined angle in the direction of rotation of the rotor relative to the vacuum chamber, and as a result, a buffer member fixed to the flange of the pump case is pulled in the direction of rotation of the rotor and plastically deforms (or plastically deforms and eventually breaks).

[0006] By configuring it in this manner, part of the torque (i.e., rotational energy) generated in the entire molecular pump in the event of an abnormality is absorbed by the plastic deformation of the buffer member, thereby reducing the impact torque applied to the vacuum chamber.

[0007] Japanese Patent Application Laid-Open No. 2005-69194

[0008] In the molecular pump disclosed in the above-mentioned Patent Document 1, the flange provided on the pump case is fixed to the vacuum chamber by bolting, so that the axial end face of the flange is in a state of tightly adhering to the end face of the vacuum chamber after being fixed. In addition, during normal operation, the internal space of the molecular pump is in a decompressed state, so that the pressure difference with the surrounding pressure (usually atmospheric pressure) causes these end faces to be in an even tighter state of adhering to each other.

[0009] Therefore, in the molecular pump disclosed in Patent Document 1, when an abnormality occurs, the flange of the pump case rotates relative to the vacuum chamber, which not only causes energy absorption due to plastic deformation of the buffer member, but also inevitably causes energy absorption due to the sliding friction between the end faces described above.

[0010] The frictional force generated between these end faces varies greatly depending on the surface condition of the end faces and the fastening force (i.e., tightening torque) of the bolts, and its magnitude changes from moment to moment even during the short time that the pump case flange rotates relative to the vacuum chamber. Therefore, it is extremely difficult to specifically calculate the amount of energy absorbed by this sliding friction at the design stage.

[0011] Furthermore, since the connection between the flange of the pump case and the vacuum chamber is also the connection part for the vacuum piping, secure bolt fastening is required to ensure high rigidity and high airtightness. However, if the fastening force is too large in the molecular pump disclosed in Patent Document 1, sliding will not occur between the end faces described above even in the event of an abnormality, and as a result, plastic deformation of the buffer member will not occur, and the energy absorption effect itself may be lost.

[0012] In order to prevent this situation from occurring, special consideration is required when installing the molecular pump in the vacuum chamber to ensure both secure bolt fastening and secure energy absorption. However, this is equivalent to adjusting the frictional force generated between the end faces in advance, which is extremely difficult.

[0013] Therefore, when adopting the configuration disclosed in the above-mentioned Patent Document 1, in order to reliably mitigate the impact torque on the vacuum chamber in the event of an abnormality, it is necessary to repeatedly design a molecular pump, manufacture a prototype, and perform experiments to reproduce abnormalities using the prototype, etc., which is one of the factors that lengthen the development period of the molecular pump and increase the manufacturing cost.

[0014] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a molecular pump that can reliably mitigate the impact torque applied to the vacuum chamber in the event of an abnormality, without lengthening the development period or increasing the manufacturing cost.

[0015] A molecular pump according to the present invention is provided with an attachment part for a vacuum chamber and includes a pump case, a stator, a rotor, and a rotation drive mechanism. The pump case includes a cylindrical body having an intake port at one axial end of the body, and the attachment part is provided to surround the intake port. The stator is immovably held by the pump case, and the rotor is rotatably supported by the pump case. The rotation drive mechanism is for driving the rotor to rotate. The attachment part includes a base part having an axial end face that faces the vacuum chamber when the attachment part is attached to the vacuum chamber, a stop part that is fastened to the vacuum chamber in the attached state, an arm part that connects the base part and the stop part, and a fixture that fixes the stop part to the vacuum chamber. In the molecular pump based on the present invention, the end of the stopper portion, which will be located on the vacuum chamber side in the mounted state, protrudes toward the vacuum chamber side beyond the axial end face of the base portion, so that in the mounted state, the base portion and the arm portion are configured to be out of contact with the vacuum chamber.

[0016] According to the present invention, it is possible to provide a molecular pump that can reliably mitigate the impact torque applied to the vacuum chamber in the event of an abnormality, and that does not involve a long development period or an increase in manufacturing costs.

[0017] 1 is a schematic cross-sectional view showing a state in which a composite molecular pump according to a first embodiment is mounted to a vacuum chamber. FIG. 1 is a schematic cross-sectional view of the vacuum chamber shown in FIG. 1. FIG. 2 is a schematic plan view of a casing body and a rotor of the composite molecular pump shown in FIG. 1. FIG. 3 is a schematic plan view of the adapter shown in FIG. 1. FIG. 4 is an enlarged plan view and a cross-sectional view of a main part of the adapter shown in FIG. 5. FIG. 6 is an exploded view of a main part for explaining a mounting structure of the composite molecular pump shown in FIG. 1 to a vacuum chamber. FIG. 7 is a schematic cross-sectional view of the mounting structure shown in FIG. 6 and its vicinity, taken along the circumferential direction in the mounted state. FIG. 8 is a schematic cross-sectional view of the mounting structure shown in FIG. 6 and its vicinity, taken along the radial direction in the mounted state. FIG. 9 is a plan view and a cross-sectional view of a main part of an adapter provided in a composite molecular pump according to a first modified example. FIG. 10 is a schematic cross-sectional view of the mounting structure of the composite molecular pump according to the first modified example and its vicinity, taken along the circumferential direction in the mounted state. FIG. 11 is a plan view and a cross-sectional view of a main part of an adapter provided in a composite molecular pump according to a second modified example. FIG. 12 is a schematic cross-sectional view of the mounting structure of the composite molecular pump according to the second modified example and its vicinity, taken along the circumferential direction in the mounted state. FIG. 13 is a plan view and a cross-sectional view of a main part of an adapter provided in a composite molecular pump according to a third modified example. 22 is a schematic cross-sectional view of a mounting structure of a composite molecular pump according to a third modified example and its vicinity in a mounted state, taken along the circumferential direction. FIG. 23 is a schematic cross-sectional view of a mounting structure of a composite molecular pump according to a third modified example and its vicinity in a mounted state, taken along the radial direction. FIG. 24 is a plan view and a cross-sectional view of a main part of an adapter provided in a composite molecular pump according to a fourth modified example. FIG. 25 is a schematic cross-sectional view of a mounting structure of a composite molecular pump according to a fourth modified example and its vicinity in a mounted state, taken along the circumferential direction. FIG. 26 is a schematic cross-sectional view of a mounting structure of a composite molecular pump according to a fifth modified example and its vicinity in a mounted state. FIG. 27 is a schematic cross-sectional view of an adapter of a composite molecular pump according to a sixth modified example. FIG. 28 is a schematic cross-sectional view showing a mounted state of a composite molecular pump according to a second embodiment to a vacuum chamber. FIG. 29 is a schematic plan view of a casing main body and a rotor of the composite molecular pump shown in FIG. 21. FIG. 29 is a plan view and a cross-sectional view of a main part of the casing main body shown in FIG. 22. FIG. 29 is an exploded view of a main part for explaining the mounting structure of the composite molecular pump shown in FIG. 21 to a vacuum chamber.29 is a schematic cross-sectional view of the mounting structure of the composite molecular pump shown in FIG. 24 and its vicinity in the mounted state, taken along the circumferential direction. FIG. 30 is a schematic cross-sectional view of the mounting structure of the composite molecular pump shown in FIG. 24 and its vicinity in the mounted state, taken along the radial direction. FIG. 31 is a schematic cross-sectional view of the mounting structure of the composite molecular pump shown in FIG. 24 and its vicinity in the mounted state, taken along the radial direction. FIG. 32 is a schematic cross-sectional view showing the mounted state of the composite molecular pump according to embodiment 3 to a vacuum chamber. FIG. 33 is a schematic plan view of a casing body and a rotor of the composite molecular pump shown in FIG. 27. FIG. 34 is a schematic plan view of the adapter shown in FIG. 27. FIG. 35 is a plan view and a cross-sectional view of a main part of the adapter shown in FIG. 29. FIG. 36 is an exploded view of a main part for explaining the mounting structure of the composite molecular pump shown in FIG. 27 to a vacuum chamber. FIG. 37 is a schematic cross-sectional view of the mounting structure of the composite molecular pump shown in FIG. 31 and its vicinity in the mounted state, taken along the circumferential direction. FIG. 38 is a schematic cross-sectional view of the mounting structure of the composite molecular pump shown in FIG. 31 and its vicinity in the mounted state, taken along the radial direction.

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown below exemplify the case where the present invention is applied to a compound molecular pump equipped with a turbomolecular pump section and a thread groove vacuum pump section. In the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated.

[0019] <Embodiment 1> Fig. 1 is a schematic cross-sectional view showing a state in which a compound molecular pump according to embodiment 1 is attached to a vacuum chamber. First, with reference to Fig. 1, a general configuration of a compound molecular pump 1A according to this embodiment will be described.

[0020] 1, the compound molecular pump 1A is used by being attached to a vacuum chamber 70 of various devices to which it is attached. The compound molecular pump 1A has a mounting portion for mounting the compound molecular pump 1A to the vacuum chamber 70, and the mounting portion is provided on a pump case 10A (described later) that constitutes the outer shell of the compound molecular pump 1A.

[0021] The compound molecular pump 1A includes a turbo molecular pump section 2 and a thread groove vacuum pump section 3 as components for realizing the exhaust function, and has a generally cylindrical outer shape as a whole. The compound molecular pump 1A mainly includes a casing main body 100A, an adapter 110A, a base 20, a stator 30, a rotor 40, and a rotation drive mechanism 50.

[0022] The pump case 10A described above is composed of a casing main body 100A, an adapter 110A, a base 20, and a thread groove vacuum pump portion stator 31 of the stator 30, and the pump case 10A is provided with an intake port 13 and an exhaust port 21. Of these, the intake port 13 is located at one axial end of the cylindrical body 101 of the casing main body 100A (i.e., the upper end of the pump case 10A), and the exhaust port 21 is provided in the base 20 located at the lower end side of the pump case 10A.

[0023] In the compound molecular pump 1A according to this embodiment, the upper end of the pump case 10A, which will be located on the vacuum chamber 70 side when attached to the vacuum chamber 70, is equipped with a casing main body 100A including a body 101 and a first flange 102A (described later), as well as an adapter 110A including a second flange 112A (see FIGS. 4 to 8) (described later), and the first flange 102A, the second flange 112A, and the bolt 17 constitute a base 14 of the attachment portion. Details of the attachment portion will be described later.

[0024] The space inside the pump case 10A mainly accommodates the remaining stationary vanes 32 and spacer / support members 33 of the stator 30, the rotor 40 including a rotor body 41 and moving blades 42, and a rotation drive mechanism 50. The rotor body 41 includes an upper rotor portion 41a and a lower rotor portion 41b, and the moving blades 42 are provided in the upper rotor portion 41a. An exhaust path is also provided inside the pump case 10A, connecting the intake port 13 and the exhaust port 21.

[0025] The turbomolecular pump section 2 is mainly composed of stationary vanes 32 of the stator 30 and moving blades 42 of the rotor 40. The stationary vanes 32 and moving blades 42 are disposed inside the casing body 100A so as to face the intake port 13 provided in the casing body 100A.

[0026] A plurality of stator vanes 32 are provided on the stator 30, and these plurality of stator vanes 32 are supported by spacer / support members 33 arranged along the inner circumferential surface of the barrel portion 101 of the casing main body 100A. The spacer / support members 33 are fixed to the casing main body 100A and the thread groove vacuum pump portion stator 31, and thereby the plurality of stator vanes 32 are held immovably by the pump case 10A.

[0027] A plurality of rotor blades 42 are provided on an upper rotor portion 41a of a rotor body 41 that is disposed coaxially with the casing body 100A. The rotor 40 provided with the rotor blades 42 is fixed to an output shaft 51 of a rotation drive mechanism 50, which will be described later. As a result, the plurality of rotor blades 42 are rotatably supported by the pump case 10A via the rotation drive mechanism 50.

[0028] The plurality of stator vanes 32 and the plurality of rotor blades 42 are alternately arranged so as to face each other along the axial direction of the cylindrical body portion 101 of the casing main body 100A. As a result, the rotor 40 rotates at high speed, and the turbomolecular pump section 2 performs an exhaust function.

[0029] The thread groove vacuum pump section 3 is mainly composed of the thread groove vacuum pump section stator 31 of the stator 30 and the lower rotor section 41b of the rotor body 41 of the rotor 40. The thread groove vacuum pump section stator 31 is made of a cylindrical member and has a thread groove section 31a on its inner circumferential surface. On the other hand, the lower rotor section 41b is also cylindrical and is located inside the thread groove vacuum pump section stator 31.

[0030] Here, the lower rotor portion 41b is arranged to face the portion of the thread groove vacuum pump portion stator 31 where the thread groove portion 31a is provided. As a result, the rotor 40 rotates at high speed, and the thread groove vacuum pump portion 3 performs its exhaust function.

[0031] The rotary drive mechanism 50 has an output shaft 51 rotatably supported by a bearing, a motor that rotates the output shaft 51, and a housing 52 that houses the bearing, the motor, and a part of the output shaft 51. The output shaft 51 is disposed coaxially with the trunk portion 101 of the casing main body 100A.

[0032] The upper end portion of the output shaft 51 is pulled out from the housing 52 to the outside, and the rotor body 41 is fixed to the portion of the output shaft 51 pulled out from the housing 52. As a result, the rotation drive mechanism 50 can rotate the rotor 40 at high speed in the direction of the arrow DR1 shown in the figure (hereinafter, this direction will be referred to as the rotation direction DR1) around the rotation axis RA shown in the figure, which is defined by the output shaft 51.

[0033] Here, the turbomolecular pump section 2 is arranged at a position downstream of the intake port 13 in the exhaust path, and the thread groove vacuum pump section 3 is arranged at a position downstream of the turbomolecular pump section 2 in the exhaust path and upstream of the exhaust port 21. As a result, in the compound molecular pump 1A, the gas to be exhausted moves and is exhausted in the order of the intake port 13, turbomolecular pump section 2, thread groove vacuum pump section 3, and exhaust port 21.

[0034] Sealing members such as O-rings are interposed between the casing body 100A and the stator 31 of the thread groove vacuum pump section, and between the stator 31 of the thread groove vacuum pump section and the base 20. This ensures airtightness of the exhaust path from the intake port 13 to the exhaust port 21, and prevents air leakage between the members that form the exhaust path.

[0035] Fig. 2 is a schematic cross-sectional view of the vacuum chamber shown in Fig. 1 as viewed along line II-II in Fig. 1, with Fig. 2 showing only the vacuum chamber. Fig. 3 is a schematic plan view of the casing body and rotor shown in Fig. 1 as viewed along line III-III in Fig. 1, with Fig. 3 showing only the casing body and rotor. Fig. 4 is a schematic plan view of the adapter shown in Fig. 1 as viewed along line IV-IV in Fig. 1, with Fig. 4 showing only the adapter. Next, with reference to Figs. 2 to 4 and the aforementioned Fig. 1, the configuration of a vacuum chamber 70 to which a composite molecular pump 1A according to this embodiment is attached, the general configuration of a mounting portion provided on the composite molecular pump 1A, and the general configuration of the composite molecular pump 1A in an attached state to the vacuum chamber 70 will be described. Although the rotor 40 itself, which is rotated, is not shown in Figures 2 and 4, its rotation axis RA and its rotation direction DR1 are shown schematically to show the relative positional relationship between the rotor 40 and the vacuum chamber 70 and the adapter 110A when they are attached.

[0036] 1, the compound molecular pump 1A according to this embodiment is fixed to a vacuum chamber 70 by using bolts 15 and nuts 16, which are fastening members serving as fixing devices. As a result, when the compound molecular pump 1A is attached to the vacuum chamber 70, the intake port 13 provided in the pump case 10A communicates with the internal space of the vacuum chamber 70.

[0037] Here, in the composite molecular pump 1A according to this embodiment, as will be described later, of the casing body 100A and the adapter 110A, only the end face of the stopper portion 115 of the adapter 110A on the vacuum chamber 70 side is in contact with the vacuum chamber 70 in the attached state, so that the composite molecular pump 1A is directly fixed to the vacuum chamber 70 (see FIGS. 7 and 8).

[0038] 1 and 2, the vacuum chamber 70 has a container-like shape made of, for example, a metal member, and includes a body 71 and a flange 72. The body 71 has an opening 71a in a portion that faces the compound molecular pump 1A in the installed state, and the flange 72 is positioned so as to protrude outward from the end of the body 71 and surround this opening 71a. The axis of the opening 71a of the vacuum chamber 70 coincides with the rotation axis RA of the rotor 40 of the compound molecular pump 1A in the installed state.

[0039] A plurality of through holes 72a are provided in the flange portion 72. The plurality of through holes 72a are arranged side by side at a distance from one another along the circumferential direction of the flange portion 72. Each of the plurality of through holes 72a penetrates the flange portion 72 along the axial direction of the body portion 71 so as to reach each of a pair of main surfaces of the flange portion 72. These plurality of through holes 72a are used when mounting the compound molecular pump 1A to the vacuum chamber 70.

[0040] 1 and 3, the casing body 100A of the compound molecular pump 1A has a generally cylindrical shape and is made of, for example, a metal member, and includes a body 101, a first flange 102A, a plurality of first cutouts 103A in the form of through-holes, and a plurality of screw holes 106a in the form of through-holes. An intake port 13 is provided at one axial end of the body 101. The first flange 102A is a substantial portion that protrudes outward from the one end of the body 101 so as to surround the intake port 13, and the first cutouts 103A and the screw holes 106a are cutouts provided in that portion.

[0041] The first flange portion 102A includes a first main surface 102a that is positioned on the vacuum chamber 70 side when attached, and a second main surface 102b (see Figures 6 to 8) that is positioned on the opposite side from the vacuum chamber 70 side (i.e., the body portion 101 side) when attached.

[0042] The plurality of first cutouts 103A are arranged side by side at a distance from one another along the circumferential direction of the first flange portion 102A. Each of the plurality of first cutouts 103A is configured as an elongated hole extending along the circumferential direction of the first flange portion 102A, and penetrates the first flange portion 102A along the axial direction of the casing body 100A so as to reach both the first main surface 102a and the second main surface 102b of the first flange portion 102A.

[0043] The plurality of fixing screw holes 106a penetrate the first flange portion 102A along the axial direction of the casing main body 100A so as to reach both the first main surface 102a and the second main surface 102b of the first flange portion 102A. The plurality of fixing screw holes 106a are used to fix an adapter 110A, which is configured separately from the casing main body 100A, to the casing main body 100A.

[0044] 1 and 4, the adapter 110A of the compound molecular pump 1A is composed of two parts each having a substantially semicircular annular plate shape and made of, for example, a metal member, and these two parts are combined to form a substantially annular plate shape as a whole. The adapter 110A includes a plurality of arm portions 114, a plurality of abutting portions 115, a substantially annular plate-shaped second flange portion 112A which is the substantial portion of the remaining portion, a plurality of through-hole-shaped second cutout portions 113A, and a plurality of through-hole-shaped fixing holes 116a.

[0045] The second flange portion 112A includes a third main surface 112a that is positioned on the vacuum chamber 70 side in the attached state, and a fourth main surface 112b (see FIGS. 6 to 8, etc.) that is positioned on the opposite side from the vacuum chamber 70 in the attached state. The axis of the second flange portion 112A coincides with the rotation axis RA of the rotor 40 of the compound molecular pump 1A in the attached state.

[0046] The second cutouts 113A are arranged corresponding to the first cutouts 103A provided in the first flange 102A of the casing body 100A, and are positioned side by side at a distance from one another along the circumferential direction of the adapter 110A. Each of the second cutouts 113A is configured as an elongated hole extending along the circumferential direction of the adapter 110A, and penetrates the second flange 112A along the axial direction of the adapter 110A so as to reach both the third main surface 112a and the fourth main surface 112b of the second flange 112A.

[0047] The plurality of arm portions 114 are provided corresponding to the plurality of second cutout portions 113A. Each of the plurality of arm portions 114 extends so as to protrude in the circumferential direction of adapter 110A from the wall surface of second flange portion 112A at a portion that defines the corresponding second cutout portion 113A, and is thereby accommodated in second cutout portion 113A.

[0048] The plurality of stopper portions 115 are provided corresponding to the plurality of arm portions 114. Each of the plurality of stopper portions 115 is located at the tip of the corresponding arm portion 114, and each of the plurality of stopper portions 115 is provided with a hole portion 115a that penetrates along the axial direction of the adapter 110A. The hole portion 115a provided in each of the plurality of stopper portions 115 is used when attaching the compound molecular pump 1A to the vacuum chamber 70.

[0049] Each of the plurality of fixing holes 116a penetrates the second flange portion 112A along the axial direction of the adapter 110A so as to reach both the third main surface 112a and the fourth main surface 112b of the second flange portion 112A. These fixing holes 116a are used to fix the adapter 110A, which is configured separately from the casing main body 100A, to the casing main body 100A.

[0050] 1 and 7 and 8 described later, in the compound molecular pump 1A according to this embodiment, the adapter 110A is fixed to the casing main body 100A while being fitted onto the second main surface 102b of the first flange portion 102A of the casing main body 100A. That is, the casing main body 100A and the adapter 110A are secured together with the second main surface 102b and the third main surface 112a in contact with each other, and are secured together with the bolts 17. As a result, the first flange portion 102A of the casing main body 100A, the second flange portion 112A of the adapter 110A, and the bolts 17 are substantially integrated, thereby constituting the base portion 14 of the mounting portion.

[0051] Therefore, when the composite molecular pump 1A is attached to the vacuum chamber 70, the second flange portion 112A of the adapter 110A is positioned on the opposite side of the vacuum chamber 70 from the first flange portion 102A of the casing main body 100A, and therefore the axial end surface 14a of the base portion 14 that faces the vacuum chamber 70 in this attached state is defined by the first main surface 102a of the first flange portion 102A.

[0052] Here, in the compound molecular pump 1A according to this embodiment, the first cut-out portion 103A, the second cut-out portion 113A, the arm portion 114, the stop portion 115, the bolt 15, and the nut 16 are provided in correspondence with one another, and a combination of these first cut-out portion 103A, the second cut-out portion 113A, the arm portion 114, the stop portion 115, the bolt 15, and the nut 16 fixes the base portion 14 of the mounting portion of the compound molecular pump IA to the flange portion 72 of the vacuum chamber 70, thereby forming one mounting structure for mounting the compound molecular pump 1A to the vacuum chamber 70. A plurality of these mounting structures are provided in a dotted row along the circumferential direction of the pump case 10A, and the compound molecular pump 1A and the vacuum chamber 70 are fixed to each other at each of these plurality of mounting structures, thereby enabling the compound molecular pump 1A to be firmly and reliably fixed to the vacuum chamber 70.

[0053] However, as shown in Fig. 4, in the compound molecular pump 1A according to this embodiment, the mounting structure located at one end in the circumferential direction of each of the two substantially semicircular plate-shaped components that make up the adapter 110A does not have the second cutout 113A. Here, the mounting structure located at one end corresponds to the mounting structure located at the left end of the upper component shown in Fig. 4, and corresponds to the mounting structure located at the right end of the lower component shown in Fig. 4.

[0054] 1 and 3, an annular recess 107 extending along the circumferential direction of the first flange portion 102A is provided in the first main surface 102a of the first flange portion 102A that defines the axial end surface 14a of the base portion 14. A sealing member 60 made of an elastic material, such as an O-ring made of fluororubber, is disposed in the annular recess 107.

[0055] 1, the sealing member 60 is interposed between the casing main body 100A and the vacuum chamber 70. Therefore, in the installed state, the gap between the casing main body 100A and the vacuum chamber 70 is sealed by the sealing member 60, thereby preventing air leakage from this portion.

[0056] Fig. 5(A) is an enlarged plan view of region VA shown in Fig. 4 of the adapter shown in Fig. 4, and Fig. 5(B) is a cross-sectional view taken along line VB-VB in Fig. 5(A). Fig. 6 is an exploded view of essential parts for explaining the mounting structure of the composite molecular pump shown in Fig. 1 to a vacuum chamber. Figs. 7 and 8 are schematic cross-sectional views taken along the circumferential and radial directions, respectively, of the mounting structure shown in Fig. 6 and its vicinity in the mounted state. In particular, Fig. 8 is a schematic cross-sectional view taken along line VIII-VIII in Fig. 7. Next, with reference to Figs. 5(A), 5(B), and 6 to 8, the detailed configuration of the mounting portion of the composite molecular pump 1A according to this embodiment, the procedure for mounting the composite molecular pump 1A to a vacuum chamber 70, and the detailed configuration of the composite molecular pump 1A in the mounted state mounted to the vacuum chamber 70 will be described.

[0057] 5A, 5B, 6 to 8 show only one of the mounting structures arranged in a dotted row around the circumferential direction of the casing body 100A, or a portion included in that one mounting structure. The following description focuses on the configuration of that one mounting structure, but the configurations of the other mounting structures are basically the same. Also, in Fig. 5A, 5B, and 7, the rotation direction DR1 of the rotor 40 is shown schematically. In Fig. 5A, the through-hole 72a in the vacuum chamber 70 is shown by a dashed line to show the relative positional relationship between the adapter 110A, the casing body 100A, and the vacuum chamber 70 in the attached state, and the first cutout 103A in the casing body 100A is shown by a dashed line.

[0058] As shown in Figures 5(A) and 5(B), the adapter 110A mainly includes a second flange portion 112A as the base portion 14, a second cut-out portion 113A, an arm portion 114, a stopper portion 115, and a fixing hole 116a.

[0059] Arm portion 114 extends from a wall surface of second flange portion 112A at a portion that defines second cutout portion 113A, on one end side of second flange portion 112A in the circumferential direction, so as to protrude in the circumferential direction of second flange portion 112A. The protruding direction of arm portion 114 is opposite to rotation direction DR1 of rotor 40, and the wall surface on the one end side in the circumferential direction of second flange portion 112A is the downstream wall surface along rotation direction DR1 of rotor 40 (the wall surface located on the left side in the drawing).

[0060] In the illustrated adapter 110A, an elongated hole is provided in the arm portion 114, and a recess is provided on the underside of the arm portion 114. The hole and recess are provided for adjusting the cross-sectional area of ​​the arm portion 114 perpendicular to the rotation direction DR1 of the rotor 40 to an appropriate size, but the adjustment of the cross-sectional area of ​​the arm portion 114 will be described in detail later.

[0061] The stopper portion 115 extends along the thickness direction of the second flange portion 112A, and in particular protrudes a predetermined height toward its upper side (i.e., the side where the vacuum chamber 70 is located when attached).

[0062] Furthermore, second cutout portion 113A provided in adapter 110A is formed to extend further in the opposite direction to rotational direction DR1 of rotor 40 than the portion that accommodates stopper portion 115. That is, of the wall surface of second flange portion 112A at the portion that defines second cutout portion 113A, the wall surface on the other end side in the circumferential direction of second flange portion 112A, which is the wall surface on which arm portion 114 is provided, is positioned a predetermined distance away from stopper portion 115.

[0063] 6, the multiple fixing holes 116a provided in the second flange portion 112A of the adapter 110A serving as the base portion 14 are arranged to correspond to the multiple fixing screw holes 106a provided in the first flange portion 102A of the casing main body 100A serving as the base portion 14. Therefore, when the second flange portion 112A of the adapter 110A is fitted to the first flange portion 102A of the casing main body 100A, the multiple fixing holes 116a and the multiple fixing screw holes 106a overlap, and by screwing bolts 17 into the multiple fixing screw holes 106a through the multiple fixing holes 116a, the adapter 110A is fixed to the casing main body 100A.

[0064] 5A and 6, a portion of second cutout 113A provided in adapter 110A is disposed corresponding to first cutout 103A provided in casing main body 100A. Therefore, when adapter 110A is fixed to casing main body 100A, a portion of second cutout 113A overlaps first cutout 103A.

[0065] 5A and 6, the stopper 115 provided on the adapter 110A is also disposed in correspondence with the first cutout 103A provided on the casing main body 100A. Therefore, when the adapter 110A is fixed to the casing main body 100A, the stopper 115 also overlaps the first cutout 103A, and a portion of the stopper 115 is accommodated in the first cutout 103A. As shown in FIGS. 5A and 7, the upstream wall surface of the first flange 102A defining the first cutout 103A in the direction of rotation DR1 of the rotor 40 is located a predetermined distance away from the stopper 115, similar to the second cutout 113A provided on the second flange 112A.

[0066] 5A and 6, the plurality of holes 115a formed in the adapter 110A are arranged to correspond to the plurality of through holes 72a formed in the flange portion 72 of the vacuum chamber 70. Therefore, when the adapter 110A is fixed to the casing main body 100A, the casing main body 100A is further disposed so as to face the flange portion 72 of the vacuum chamber 70, so that the plurality of holes 115a and the plurality of through holes 72a overlap. By inserting bolts 15 into the plurality of holes 115a and the plurality of through holes 72a and screwing nuts 16 onto the bolts 15, the adapter 110A is fixed to the vacuum chamber 70. In this way, the compound molecular pump 1A including the casing main body 100A and the adapter 110A is attached to the vacuum chamber 70.

[0067] By using the adapter 110A having the configuration described above, the compound molecular pump 1A is attached to the vacuum chamber 70 according to the following procedure with reference to FIG.

[0068] In the first step, the adapter 110A is assembled to the casing main body 100A. Specifically, first, the third main surface 112a of the adapter 110A is aligned with the second main surface 102b of the first flange portion 102A of the casing main body 100A. At this time, the abutting portion 115 provided on the adapter 110A is inserted into the first cutout portion 103A provided on the first flange portion 102A of the casing main body 100A, and the adapter 110A is positioned relative to the casing main body 100A so that the multiple fixing holes 116a provided on the adapter 110A overlap the multiple fixing screw holes 106a provided on the first flange portion 102A of the casing main body 100A. Next, with the adapter 110A positioned in this state, the bolts 17 are screwed into the fixing screw holes 106a. This completes the assembly of the adapter 110A to the casing main body 100A.

[0069] In the second step, the adapter 110A is assembled to the vacuum chamber 70. Specifically, with the adapter 110A assembled to the casing main body 100A, the first main surface 102a of the first flange portion 102A of the casing main body 100A is positioned so that it faces the flange portion 72 of the vacuum chamber 70. At this time, the adapter 110A is positioned relative to the vacuum chamber 70 so that the hole 115a of the stopper portion 115 provided on the adapter 110A overlaps the through hole 72a provided in the flange portion 72 of the vacuum chamber 70, and the end of the stopper portion 115 contacts the end surface of the flange portion 72 of the vacuum chamber 70. Next, with the adapter 110A positioned in this manner, the bolt 15 is inserted into the overlapping through hole 72a and the hole 115a, and the nut 16 is screwed onto the tip of the bolt 15. In this manner, the adapter 110A is assembled to the vacuum chamber 70.

[0070] By going through the procedure described above, the first flange portion 102A of the casing body 100A is fixed to the flange portion 72 of the vacuum chamber 70 via the adapter 110A, thereby attaching the composite molecular pump 1A to the vacuum chamber 70.

[0071] When the compound molecular pump 1A is attached to the vacuum chamber 70, the mounting structure and its surroundings are configured as shown in FIGS.

[0072] That is, as shown in FIGS. 7 and 8, at the connection portion between the compound molecular pump 1A and the vacuum chamber 70, the flange portion 72 of the vacuum chamber 70, the first flange portion 102A of the casing body 100A, and the second flange portion 112A of the adapter 110A are stacked in this order from top to bottom along the axial direction of the casing body 100A, and a part of the second cutout portion 113A provided in the adapter 110A overlaps with the first cutout portion 103A provided in the casing body 100A. The stopper 115 provided on the adapter 110A is positioned across the first cutout 103A and the area of ​​the second cutout 113A that overlaps with the first cutout 103A, the second flange 112A of the adapter 110A and the first flange 102A of the casing main body 100A are fixed together by bolts 17, and the stopper 115 provided on the adapter 110A and the flange 72 of the vacuum chamber 70 are fastened together by bolts 15 and nuts 16 that serve as fixing devices.

[0073] In the compound molecular pump 1A according to this embodiment, the end of the stopper portion 115, which will be located on the vacuum chamber 70 side in the mounted state, is configured to protrude toward the vacuum chamber 70 beyond the axial end face 14a of the base portion 14, which is formed by the first flange portion 102A of the casing body 100A and the second flange portion 112A of the adapter 110A. As a result, in the mounted state, the axial end face 14a of the base portion 14 is not in contact with the vacuum chamber 70, and furthermore, the arm portion 114 is not in contact with the vacuum chamber 70 either. The only point in direct contact with the vacuum chamber 70 is the end face of the stopper portion 115 on the adapter 110A facing the vacuum chamber 70 (i.e., the area surrounded by the dashed line indicated by symbol α in the figure). Therefore, the contact area of ​​the direct contact portion of the compound molecular pump 1A with the vacuum chamber 70 is minimized.

[0074] That is, a gap G is formed between the flange portion 72 of the vacuum chamber 70 and the base portion 14, and the size of this gap G is determined by the protruding height h of the stopper portion 115 that protrudes from the axial end face 14a of the base portion 14 toward the vacuum chamber 70. Note that the size of the protruding height h is not particularly limited, but it is preferably sufficiently smaller than the groove depth required to install a sealing member such as an O-ring, for example, between 0.05 mm and 0.2 mm.

[0075] With this configuration, if some abnormality (such as an earthquake or the intake of a foreign object) occurs during operation of the compound molecular pump 1A, causing the rotor 40, which is rotating at high speed, to come into contact with another member such as the stator 30, and as a result, the angular momentum of the rotor 40 is applied as an impact torque to the vacuum chamber 70 via the pump case 10A, it is possible to significantly reduce the magnitude of the impact torque. The reason for this will be explained in detail below.

[0076] As mentioned above, one known method for mitigating the impact torque that may occur during the above-mentioned abnormality is to dissipate part of the generated torque through friction that occurs between the pump case and the vacuum chamber. However, it is extremely difficult to specifically calculate the energy consumption due to this friction at the design stage, and this method is not necessarily the optimal method for mitigating the impact torque applied to the vacuum chamber.

[0077] In this regard, in the composite molecular pump 1A according to this embodiment, by employing the above-described configuration, the base portion 14 and the arm portion 114 are kept out of contact with the vacuum chamber 70, and the area of ​​the direct contact portion of the composite molecular pump 1A with the vacuum chamber 70 is minimized as much as possible, as described above. As a result, energy consumption due to friction is substantially eliminated, and instead, the energy is substantially consumed by plastic deformation of the arm portion 114 provided on the adapter 110A, thereby making it possible to mitigate the impact torque applied to the vacuum chamber 70.

[0078] Specifically, referring to Figures 5(A), 5(B) and 7, in the event of an abnormality, when the rotor 40 rotating at high speed comes into contact with another member, the angular momentum of the rotor 40 is transmitted to the pump case 10A, and as a result, a torque is generated that rotates the entire compound molecular pump 1A in the same direction as the rotation direction DR1 of the rotor 40.

[0079] The generated torque is applied to the mounting structure described above, which is the mounting portion for vacuum chamber 70, and at that time, this becomes a tensile load that is applied to arm portion 114 of adapter 110A, which is the portion most susceptible to deformation (in the drawing, the direction in which this tensile load is applied is schematically represented by arrow DR2). As a result, arm portion 114 undergoes plastic deformation (tensile deformation) due to this tensile load.

[0080] At this time, as described above, the stopper portion 115 provided at the tip of the arm portion 114 is located a predetermined distance away from the upstream wall surface of the second flange portion 112A in the portion that defines the second cutout portion 113A, along the rotation direction DR1 of the rotor 40, and is also located a predetermined distance away from the upstream wall surface of the first flange portion 102A in the portion that defines the first cutout portion 103A, along the rotation direction DR1 of the rotor 40, thereby preventing the stopper portion 115 from coming into contact with the second flange portion 112A and the first flange portion 102A.

[0081] Furthermore, in the compound molecular pump 1A according to this embodiment, as described above, the mounting structure located at one end in the circumferential direction of the mounting structures of each of the two substantially semicircular plate-shaped components that make up the adapter 110A does not have the second cutout 113A, but instead is configured so that a sufficient space is formed around the arm portion 114 and the stopper portion 115 of the mounting structure located at this end in the mounted state. Therefore, by configuring it in this way, the arm portion 114 and the stopper portion 115 of the mounting structure located at this end are also prevented from coming into contact with the second flange portion 112A.

[0082] Therefore, energy is consumed by the plastic deformation of arm portion 114, resulting in a significant reduction in the impact torque applied to vacuum chamber 70. Furthermore, as described above, at this time, because base portion 14 and arm portion 114 are not in contact with vacuum chamber 70, no friction occurs between them, and the energy is consumed substantially solely through the plastic deformation of arm portion 114.

[0083] Unlike energy consumption due to friction, energy consumption due to plastic deformation (tensile deformation) of the arm portion 114 can be specifically calculated at the design stage. That is, the amount of energy consumption due to plastic deformation of the arm portion 114 can be calculated in advance at the design stage based on the material and cross-sectional area of ​​the arm portion 114. Therefore, by appropriately selecting and adjusting the material and cross-sectional area of ​​the arm portion 114, it is possible to design in advance the amount of mitigation of the impact torque applied to the vacuum chamber 70 in the event of an abnormality.

[0084] The cross-sectional area of ​​arm portion 114 can be adjusted, for example, by providing holes or recesses in arm portion 114 as described above, or by appropriately setting the size and shape of arm portion 114 itself. In particular, if the cross-sectional area of ​​arm portion 114 is adjusted by a recess provided on the top surface of arm portion 114 as shown in Fig. 7, arm portion 114 will not come into contact with casing main body 100A in the attached state, and friction can be avoided here as well.

[0085] Furthermore, if the generated impact torque is reduced by such a method, the amount of reduction can be calculated in advance, and therefore, compared to conventional known methods, it is possible to significantly reduce the number of times that the composite molecular pump needs to be designed, a prototype manufactured, and an experiment to reproduce an abnormality using the prototype is performed, thereby shortening the development period of the composite molecular pump and reducing the manufacturing cost.

[0086] Therefore, by using the composite molecular pump 1A according to this embodiment, it is possible to reliably reduce the impact torque applied to the vacuum chamber 70 in the event of an abnormality, and it is possible to provide a composite molecular pump that does not require a long development period or an increase in manufacturing costs. Furthermore, since the impact torque applied to the vacuum chamber 70 in the event of an abnormality can be known in advance, it becomes easier to design the strength of the vacuum chamber 70, and in this respect too, it is possible to prevent damage to the vacuum chamber 70.

[0087] An example of a specific example of energy consumption due to plastic deformation of the arm portion 114 in the compound molecular pump 1A according to the present embodiment described above, calculated by simulation, will be described below.

[0088] The compound molecular pump according to this example has a pumping performance of 3000 [L / s] class. The moment of inertia I of the rotor in the compound molecular pump during normal operation is ｒ is 0.04029 [kgm ２ ], and the rotor rotation angular velocity during normal operation is set to ω ｎ is set to 2827 [Rad / s] (450 [rpm]), and the moment of inertia I of the part of the compound molecular pump excluding the rotor is ｓ is 1.52 [kgm ２ These values ​​are typical values ​​for compound molecular pumps with this class of pumping performance. Note that the motion that causes plastic deformation in the arm section is actually a motion along the circumferential direction, but in this simulation, this was approximated as a translational motion.

[0089] Here, the following equation (1) holds during normal operation, and the following equations (2) and (3) hold when an abnormality occurs. The occurrence of an abnormality refers to the point in time when the rotor, rotating at high speed, comes into contact with another component and the angular momentum of the rotor is transmitted to the entire compound molecular pump. This corresponds to the situation where the largest impact torque occurs. Note that K is the rotational energy of the rotor during normal operation, ω' is the rotational angular velocity of the entire compound molecular pump when an abnormality occurs, and K' is the rotational energy of the entire compound molecular pump when an abnormality occurs.

[0090] K = (1 / 2) x I ｒ ×ω ｎ ２ Formula (1) I ｒ ×ω ｎ = (I ｒ +I ｓ )×ω'... Formula (2) K'=(1 / 2)×(I ｒ +I ｓ )×ω' ２ ... Formula (3)

[0091] From these formulas (1) to (3), the rotational energy K' of the entire compound molecular pump when an abnormality occurs in the compound molecular pump according to this example can be calculated to be 4159 [J].

[0092] Here, in the compound molecular pump according to this example, the adapter including the arm portion is made of SUS304 (chromium content: 18 wt %, nickel content: 8 wt %), which is a typical austenitic stainless steel. Also, in the compound molecular pump according to this example, 12 mounting structures are provided evenly along the circumferential direction of the pump case. In addition, in the compound molecular pump according to this example, since the above-mentioned holes are provided in the arm portion, there are essentially two arm portions, and the cross-sectional area and length of each arm portion are 14 mm. ２ ] and 40.36 [mm].

[0093] In this case, the energy E that can be consumed by plastic deformation of one arm portion is １ [J] can be calculated using the elongation rate ε of the arm portion according to the following formula (4): Note that, although the tensile stress when rapid strain occurs in SUS304 actually changes correspondingly with the increase in strain, in this simulation, this was assumed to be constant at 650 [MPa] to simplify the calculation.

[0094] E １ = 650 x 10 ６ x14 x 10 －６ x 40.36 x 10 －３ ×ε=367.3×ε... Formula (4)

[0095] Here, assuming that the rotational energy K' of the entire compound molecular pump when the above-mentioned abnormality occurs is consumed entirely by the plastic deformation of the arm portions, since the compound molecular pump according to this example has a total of 24 arm portions as described above, the energy E (=24×E) that can be consumed by the plastic deformation of all of these 24 arm portions is １ ) is equal to the rotational energy K′, and the following equation (5) is obtained.

[0096] 24×367.3×ε=4159... Formula (5)

[0097] As a result, the elongation rate ε of each arm portion is 0.472, and the elongation can be calculated as approximately 19 mm. Considering that the material of the arm portion is SUS304, this elongation per arm portion is not enough to cause breakage or the like in the arm portion. Furthermore, by setting the circumferential distance (i.e., the dimension of the gap formed between the stop fastening portion and the wall surface of the second flange portion (i.e., the wall surface of the second flange portion that defines the second cutout portion and is located opposite the wall surface on which the arm portion is provided) to a value greater than approximately 19 mm, contact between the stop fastening portion and the second flange portion can be avoided.

[0098] Furthermore, the total circumferential force applied to the 24 arms at the time when the arms are stretched is calculated using the following equation (6) based on the cross-sectional area and tensile stress of the arms described above.

[0099] 24 x 650 x 10 ６ x14 x 10 －６ =218400[N]... Formula (6)

[0100] Furthermore, if the radius of the pitch circle of the bolts that secure the compound molecular pump and the vacuum chamber in the compound molecular pump according to this example is 185 mm, the torque generated by the above-mentioned circumferential force is calculated by the following equation (7).

[0101] 218400 x 185 x 10 －３ =40404[N・m]... Formula (7)

[0102] The torque generated in the event of an abnormality in the composite molecular pump according to this embodiment is approximately 60% of the torque generated in the event of an abnormality in a conventional composite molecular pump to which the present invention is not applied (i.e., a composite molecular pump whose configuration other than that related to the mounting portion described above is the same as that of the composite molecular pump according to this embodiment, and whose structure is such that the flange portion of the casing body is directly fixed to the flange portion of the vacuum chamber with bolts without using an adapter).

[0103] Therefore, based on this result, it can be said that it has been confirmed that in the compound molecular pump according to this example, when an abnormality occurs and the angular momentum of the rotor is transmitted to the pump case, the energy consumption can be substantially realized only by the plastic deformation of the arm portion provided on the adapter, and therefore, it is possible to significantly reduce the impact torque applied to the vacuum chamber.

[0104] <First Modification> Fig. 9(A) is a plan view of a main part of an adapter provided in a composite molecular pump according to a first modification, and Fig. 9(B) is a cross-sectional view taken along line IXB-IXB shown in Fig. 9(A). Fig. 10 is a schematic cross-sectional view taken along the circumferential direction of the mounting structure of the composite molecular pump according to the first modification and its vicinity in an attached state. Hereinafter, a composite molecular pump 1A1 according to a first modification based on embodiment 1 will be described with reference to Figs. 9(A), 9(B), and 10.

[0105] 9(A), 9(B), and 10, the compound molecular pump 1A1 according to the first modification includes a pump case 10A1 instead of the pump case 10A included in the compound molecular pump 1A according to the first embodiment, and the pump case 10A1 includes a casing main body 100A1 and an adapter 110A1. The casing main body 100A1 has basically the same configuration as the casing main body 100A, but the adapter 110A1 has a different configuration from the adapter 110A.

[0106] 9(A) and 9(B), the second flange 112A of the adapter 110A1 serving as the base 14 of the mounting portion is mainly provided with a second cutout 113A, an arm 114, a stopper 115 with a hole 115a, and a fixing hole 116a. The only difference from the first embodiment is that the arm 114 does not have a cutout hole.

[0107] The arm portion 114 extends so as to protrude in the circumferential direction of the second flange portion 112A from the downstream wall surface (the wall surface located on the left side in the drawing) of the wall surface of the second flange portion 112A that defines the second cutout portion 113A in the direction of rotation DR1 of the rotor 40, whereby the arm portion 114 is accommodated in the second cutout portion 113A. The second cutout portion 113A is also formed so as to extend further in the opposite direction to the direction of rotation DR1 of the rotor 40 than the portion that accommodates the stopper portion 115, and the upstream wall surface (the wall surface located on the right side in the drawing) of the wall surface of the second flange portion 112A that defines the second cutout portion 113A in the direction of rotation DR1 of the rotor 40 is positioned a predetermined distance from the stopper portion 115.

[0108] As shown in FIG. 10, the end of the stopper portion 115, which will be located on the vacuum chamber 70 side in the attached state, is configured to protrude toward the vacuum chamber 70 side beyond the axial end face 14a of the base portion 14. As a result, in the attached state, the axial end face 14a of the base portion 14 is not in contact with the vacuum chamber 70, and furthermore, the arm portion 114 is not in contact with the vacuum chamber 70 either. Therefore, the only point of direct contact of the composite molecular pump 1A1 with the vacuum chamber 70 is the end face on the vacuum chamber 70 side of the stopper portion 115 provided on the adapter 110A1 (i.e., the portion surrounded by the dashed line indicated by symbol α in the figure).

[0109] Even in this configuration, as in the case of the first embodiment, if some abnormality (such as an earthquake or the ingestion of a foreign object) occurs during operation of the compound molecular pump 1A1 and causes the rotor 40, which is rotating at high speed, to come into contact with another member such as the stator 30, a tensile load will be applied to the arm portion 114 in the direction of the arrow DR2 shown in the figure, and this tensile load will cause plastic deformation (tensile deformation) of the arm portion 114.

[0110] Furthermore, as described above, at this time, the stopper portion 115 provided at the tip of the arm portion 114 is located a predetermined distance away from the upstream wall surface (the wall surface located on the right side in the figure) of the wall surface of the second flange portion 112A in the part that defines the second missing portion 113A, which prevents the stopper portion 115 from coming into contact with the second flange portion 112A.

[0111] Therefore, energy is consumed by the plastic deformation of arm portion 114, resulting in a significant reduction in the impact torque applied to vacuum chamber 70. Furthermore, as described above, at this time, because base portion 14 and arm portion 114 are not in contact with vacuum chamber 70, no friction occurs between them, and the energy is consumed substantially solely through the plastic deformation of arm portion 114.

[0112] In addition, the amount of energy consumed by the plastic deformation (tensile deformation) of the arm portion 114 differs from the energy consumed by friction, and can be calculated in advance by specifically calculating this at the design stage.

[0113] Therefore, in the case of the composite molecular pump 1A1 according to the first modified example, similarly to the first embodiment, the impact torque applied to the vacuum chamber 70 in the event of an abnormality can be reliably alleviated, and a composite molecular pump can be produced without lengthening the development period or increasing the manufacturing costs.

[0114] <Second Modification> Fig. 11(A) is a plan view of a main part of an adapter provided in a compound molecular pump according to a second modification, and Fig. 11(B) is a cross-sectional view taken along line XIB-XIB shown in Fig. 11(A). Fig. 12 is a schematic cross-sectional view taken along the circumferential direction of the mounting structure of the compound molecular pump according to the second modification and its vicinity in the mounted state. Hereinafter, a compound molecular pump 1A2 according to the second modification based on embodiment 1 will be described with reference to Figs. 11(A), 11(B), and 12.

[0115] 11(A), 11(B), and 12, the compound molecular pump 1A2 according to the second modification includes a pump case 10A2 instead of the pump case 10A included in the compound molecular pump 1A according to the first embodiment, and the pump case 10A2 includes a casing main body 100A2 and an adapter 110A2. The casing main body 100A2 has basically the same configuration as the casing main body 100A, but the adapter 110A2 has a different configuration from the adapter 110A.

[0116] 11(A) and 11(B), second flange portion 112A of adapter 110A2 serving as base portion 14 of the mounting portion is mainly provided with second cutout portion 113A, arm portion 114, stopper portion 115 with hole portion 115a, and fixing hole 116a. The main differences from embodiment 1 are that arm portion 114 does not have a cutout hole and that arm portion 114 contracts (compresses) rather than expands (tensions) in the event of an abnormality.

[0117] The arm portion 114 extends so as to protrude in the circumferential direction of the second flange portion 112A from the upstream wall surface (the wall surface located on the right side in the drawing) of the wall surface of the second flange portion 112A in a portion that defines the second cutout portion 113A, along the direction of rotation DR1 of the rotor 40, whereby the arm portion 114 is accommodated in the second cutout portion 113A. Here, the second cutout portion 113A is not formed so as to extend further in the same direction as the direction of rotation DR1 of the rotor 40 than the portion that accommodates the stopper portion 115, and the downstream wall surface (the wall surface located on the left side in the drawing) of the wall surface of the second flange portion 112A in the portion that defines the second cutout portion 113A is only formed to approximately the same position as the stopper portion 115.

[0118] As shown in FIG. 12, the end of the stopper portion 115, which will be located on the vacuum chamber 70 side in the attached state, is configured to protrude toward the vacuum chamber 70 side beyond the axial end face 14a of the base portion 14. As a result, in the attached state, the axial end face 14a of the base portion 14 is not in contact with the vacuum chamber 70, and furthermore, the arm portion 114 is also not in contact with the vacuum chamber 70. Therefore, the only point of direct contact between the composite molecular pump 1A2 and the vacuum chamber 70 is the end face on the vacuum chamber 70 side of the stopper portion 115 provided on the adapter 110A2 (i.e., the portion surrounded by the dashed line indicated by symbol α in the figure).

[0119] In the case of this configuration, unlike the first embodiment, if some abnormality (such as an earthquake or the intake of a foreign object) occurs during operation of the compound molecular pump 1A2 and causes the rotor 40, which is rotating at high speed, to come into contact with another member such as the stator 30, a compressive load will be applied to the arm portion 114 in the direction of arrow DR3 shown in the figure, and this compressive load will cause plastic deformation (compressive deformation) of the arm portion 114.

[0120] However, even in this case, energy is consumed by the plastic deformation of the arm portion 114, resulting in a significant reduction in the impact torque applied to the vacuum chamber 70. Furthermore, as described above, at this time, because the base portion 14 and the arm portion 114 are not in contact with the vacuum chamber 70, no friction occurs between them, and the energy is consumed substantially solely through the plastic deformation of the arm portion 114.

[0121] In addition, the amount of energy consumed by the plastic deformation (compression deformation) of the arm portion 114 differs from the energy consumed by friction, and can be calculated in advance by specifically calculating this at the design stage.

[0122] Therefore, in the case of the composite molecular pump 1A2 according to the second modified example, similarly to the first embodiment, the impact torque applied to the vacuum chamber 70 in the event of an abnormality can be reliably alleviated, and a composite molecular pump can be produced without lengthening the development period or increasing the manufacturing costs.

[0123] <Third Modification> Fig. 13(A) is a plan view of a main portion of an adapter provided in a composite molecular pump according to a third modification, and Fig. 13(B) is a cross-sectional view taken along line XIIIB-XIIIB in Fig. 13(A). Figs. 14 and 15 are schematic cross-sectional views, respectively, of a mounting structure of a composite molecular pump according to the third modification and its vicinity, taken along the circumferential and radial directions in the mounted state, and in particular Fig. 15 is a schematic cross-sectional view taken along line XV-XV in Fig. 14. A composite molecular pump 1A3 according to a third modification based on embodiment 1 will be described below with reference to Figs. 13(A), 13(B), 14, and 15.

[0124] 13(A), 13(B), 14, and 15, the compound molecular pump 1A3 according to the third modification includes a pump case 10A3 instead of the pump case 10A included in the compound molecular pump 1A according to embodiment 1, and the pump case 10A3 includes a casing main body 100A3 and an adapter 110A3. The casing main body 100A3 has basically the same configuration as the casing main body 100A, but the adapter 110A3 has a different configuration from the adapter 110A.

[0125] 13(A) and 13(B), second flange portion 112A of adapter 110A3 serving as base portion 14 of the mounting portion is mainly provided with second cutout portion 113A, arm portion 114, stopper portion 115 with hole portion 115a, and fixing hole 116a. Of these, the differences from embodiment 1 are mainly in that arm portion 114 does not have a cutout hole, the shape and size of second cutout portion 113A, and the extension direction of arm portion 114.

[0126] The second cutout portion 113A is a substantially rectangular hole having a predetermined width in the circumferential and radial directions of the second flange portion 112A, and penetrates the second flange portion 112A in the thickness direction of the second flange portion 112A.

[0127] The arm portion 114 extends from a wall surface of the second flange portion 112A that defines the second cutout 113A, the wall surface being located radially outward of the second flange portion 112A (the wall surface located on the lower side in FIG. 13A ), toward a wall surface being radially inward of the second flange portion 112A, thereby allowing the arm portion 114 to be accommodated in the second cutout 113A. The second cutout 113A is also formed to extend further in the opposite direction to the rotation direction DR1 of the rotor 40 than the portion that accommodates the arm portion 114 and the stopper 115 provided at its tip. The wall surface of the second flange portion 112A that defines the second cutout 113A, the upstream wall surface along the rotation direction DR1 of the rotor 40 (the wall surface located on the right side in the drawing), is located a predetermined distance away from the arm portion 114 and the stopper 115 provided at its tip. Here, the distance between the arm portion 114 and the stop portion 115 and the upstream wall surface of the second flange portion 112A described above is set to a distance that prevents the arm portion 114 from coming into contact with the upstream wall surface even if plastic deformation (bending deformation) of the arm portion 114 described below occurs.

[0128] As shown in Figures 14 and 15, the end of the stopper portion 115, which will be located on the vacuum chamber 70 side in the attached state, is configured to protrude toward the vacuum chamber 70 side beyond the axial end face 14a of the base portion 14. As a result, in the attached state, the axial end face 14a of the base portion 14 is not in contact with the vacuum chamber 70, and furthermore, the arm portion 114 is not in contact with the vacuum chamber 70 either. Therefore, the only point of direct contact of the composite molecular pump 1A3 with the vacuum chamber 70 is the end face on the vacuum chamber 70 side of the stopper portion 115 provided on the adapter 110A3 (i.e., the area surrounded by the dashed line indicated by symbol α in the figures).

[0129] In the case of this configuration, unlike the first embodiment, if some abnormality (such as an earthquake or the intake of a foreign object) occurs during operation of the compound molecular pump 1A3 and causes the rotor 40, which is rotating at high speed, to come into contact with another member such as the stator 30, a bending load will be applied to the arm portion 114 in the direction of arrow DR4 shown in the figure, and this bending load will cause plastic deformation (bending deformation) of the arm portion 114.

[0130] However, even in this case, energy is consumed by the plastic deformation of the arm portion 114, resulting in a significant reduction in the impact torque applied to the vacuum chamber 70. Furthermore, as described above, at this time, because the base portion 14 and the arm portion 114 are not in contact with the vacuum chamber 70, no friction occurs between them, and the energy is consumed substantially solely through the plastic deformation of the arm portion 114.

[0131] Furthermore, as described above, at this time, the arm portion 114 and the stop portion 115 provided at its tip are located a predetermined distance away from the upstream wall surface of the wall surface of the second flange portion 112A in the portion that defines the second missing portion 113A, along the rotation direction DR1 of the rotor 40, and therefore, the arm portion 114 and the stop portion 115 provided at its tip are also prevented from coming into contact with the second flange portion 112A.

[0132] In addition, the amount of energy consumed by the plastic deformation (bending deformation) of the arm portion 114 differs from the energy consumed by friction, and can be calculated in advance by specifically calculating this at the design stage.

[0133] Therefore, in the case of the composite molecular pump 1A3 according to the third modified example, similarly to the first embodiment, the impact torque applied to the vacuum chamber 70 in the event of an abnormality can be reliably alleviated, and a composite molecular pump can be obtained without lengthening the development period or increasing the manufacturing cost.

[0134] <Fourth Modification> Fig. 16(A) is a plan view of a main part of an adapter provided in a composite molecular pump according to a fourth modification, and Fig. 16(B) is a cross-sectional view taken along line XVIB-XVIB shown in Fig. 16(A). Also, Figs. 17 and 18 are schematic cross-sectional views, respectively, taken along the circumferential direction and the radial direction of the mounting structure of the composite molecular pump according to the fourth modification and its vicinity in the mounted state, and in particular Fig. 18 is a schematic cross-sectional view taken along line XVIII-XVIII shown in Fig. 17. A composite molecular pump 1A4 according to a fourth modification based on embodiment 1 will be described below with reference to Figs. 16(A), 16(B), 17 and 18.

[0135] 16(A), 16(B), 17 and 18, the compound molecular pump 1A4 according to the fourth modification includes a pump case 10A4 instead of the pump case 10A included in the compound molecular pump 1A according to embodiment 1, and the pump case 10A4 includes a casing main body 100A4 and an adapter 110A4. The casing main body 100A4 has basically the same configuration as the casing main body 100A, but the adapter 110A4 has a different configuration from the adapter 110A.

[0136] 16(A) and 16(B), second flange portion 112A of adapter 110A4 serving as base portion 14 of the mounting portion is mainly provided with second cutout portion 113A, arm portion 114, stopper portion 115 with hole portion 115a, and fixing hole 116a. Of these, the differences from embodiment 1 are mainly in that arm portion 114 does not have a cutout hole, the shape and size of second cutout portion 113A, and the extension direction of arm portion 114.

[0137] The second cutout portion 113A is a substantially rectangular hole having a predetermined width in the circumferential and radial directions of the second flange portion 112A, and penetrates the second flange portion 112A in the thickness direction of the second flange portion 112A.

[0138] The arm portion 114 extends from a wall surface of the second flange portion 112A that defines the second cutout 113A, the wall surface being located radially inward of the second flange portion 112A (the wall surface located on the upper side in FIG. 16A ), toward a wall surface being radially outward of the second flange portion 112A, thereby allowing the arm portion 114 to be accommodated in the second cutout 113A. The second cutout 113A is formed to extend further in the opposite direction to the rotation direction DR1 of the rotor 40 than the portion that accommodates the arm portion 114 and the stopper 115 provided at its tip. The wall surface of the second flange portion 112A that defines the second cutout 113A, the upstream wall surface along the rotation direction DR1 of the rotor 40 (the wall surface located on the right side in the drawing), is located a predetermined distance away from the arm portion 114 and the stopper 115 provided at its tip. Here, the distance between the arm portion 114 and the stop portion 115 and the upstream wall surface of the second flange portion 112A described above is set to a distance that prevents the arm portion 114 from coming into contact with the upstream wall surface even if plastic deformation (bending deformation) of the arm portion 114 described below occurs.

[0139] As shown in Figures 17 and 18, the end of the stopper portion 115, which will be located on the vacuum chamber 70 side in the attached state, is configured to protrude toward the vacuum chamber 70 side beyond the axial end face 14a of the base portion 14. As a result, in the attached state, the axial end face 14a of the base portion 14 is not in contact with the vacuum chamber 70, and furthermore, the arm portion 114 is not in contact with the vacuum chamber 70 either. Therefore, the only point of direct contact of the composite molecular pump 1A4 with the vacuum chamber 70 is the end face on the vacuum chamber 70 side of the stopper portion 115 provided on the adapter 110A4 (i.e., the portion surrounded by the dashed line indicated by symbol α in the figures).

[0140] In the case of this configuration, unlike the first embodiment, if some abnormality (such as an earthquake or the intake of a foreign object) occurs during operation of the compound molecular pump 1A4 and causes the rotor 40, which is rotating at high speed, to come into contact with another member such as the stator 30, a bending load will be applied to the arm portion 114 in the direction of arrow DR5 shown in the figure, and this bending load will cause plastic deformation (bending deformation) of the arm portion 114.

[0141] However, even in this case, energy is consumed by the plastic deformation of the arm portion 114, resulting in a significant reduction in the impact torque applied to the vacuum chamber 70. Furthermore, as described above, at this time, because the base portion 14 and the arm portion 114 are not in contact with the vacuum chamber 70, no friction occurs between them, and the energy is consumed substantially solely through the plastic deformation of the arm portion 114.

[0142] Furthermore, as described above, at this time, the arm portion 114 and the stop portion 115 provided at its tip are located a predetermined distance away from the upstream wall surface of the wall surface of the second flange portion 112A in the portion that defines the second missing portion 113A, along the rotation direction DR1 of the rotor 40, and therefore, the arm portion 114 and the stop portion 115 provided at its tip are also prevented from coming into contact with the second flange portion 112A.

[0143] In addition, the amount of energy consumed by the plastic deformation (bending deformation) of the arm portion 114 differs from the energy consumed by friction, and can be calculated in advance by specifically calculating this at the design stage.

[0144] Therefore, in the case of the composite molecular pump 1A4 according to the fourth modification, similarly to the first embodiment, the impact torque applied to the vacuum chamber 70 in the event of an abnormality can be reliably alleviated, and a composite molecular pump can be provided that does not involve a longer development period or an increase in manufacturing costs.

[0145] 19 is a schematic plan view of an adapter of a compound molecular pump according to a fifth modification. Hereinafter, a compound molecular pump 1A5 according to the fifth modification based on the first embodiment will be described with reference to this Fig. 19.

[0146] 19, the compound molecular pump 1A5 according to the fifth modification includes a pump case 10A5 instead of the pump case 10A included in the compound molecular pump 1A according to the first embodiment, and the pump case 10A5 includes a casing main body (not shown) and an adapter 110A5. The casing main body (not shown) has the same configuration as the casing main body 100A, while the adapter 110A5 has a different configuration from the adapter 110A.

[0147] Specifically, the adapter 110A includes two parts each having a substantially semicircular annular plate shape, and these two parts are combined to form a substantially circular annular plate shape as a whole (see FIG. 4, etc.). However, as shown in FIG. 19, the adapter 110A5 provided in the composite molecular pump 1A according to the fifth modified example includes four parts each having a substantially quarter-circular annular plate shape, and these four parts are combined to form a substantially circular annular plate shape as a whole.

[0148] In this case, as in the case of the first embodiment, a single mounting structure for mounting the composite molecular pump 1A5 to the vacuum chamber 70 is configured by fixing the base portion 14 of the mounting portion of the composite molecular pump 1A5 to the flange portion 72 of the vacuum chamber 70 by combining the first cut-out portion 103A, the second cut-out portion 113A, the arm portion 114, the stopper portion 115, the bolt 15, and the nut 16. However, of the mounting structures of each of the four parts having a substantially quarter-annular plate shape that configure the adapter 110A5, the mounting structure located on one end side in the circumferential direction does not have the second cut-out portion 113A, and instead is configured so that a sufficient space is formed around the arm portion 114 and the stopper portion 115 of the mounting structure located on this one end side in the mounted state.

[0149] Even when configured in this manner, as in the case of embodiment 1, it is possible to reliably mitigate the impact torque applied to the vacuum chamber 70 in the event of an abnormality, and it is possible to provide a composite molecular pump that does not require a long development period or increase in manufacturing costs.

[0150] 20 is a schematic plan view of an adapter of a compound molecular pump according to a sixth modification. Hereinafter, a compound molecular pump 1A6 according to the sixth modification based on the first embodiment will be described with reference to this Fig. 20.

[0151] 20, the compound molecular pump 1A6 according to the sixth modification includes a pump case 10A6 instead of the pump case 10A included in the compound molecular pump 1A according to the first embodiment, and the pump case 10A6 includes a casing body (not shown) and an adapter 110A6. The casing body (not shown) has the same configuration as the casing body 100A, while the adapter 110A6 has a different configuration from the adapter 110A.

[0152] Specifically, the adapter 110A includes two parts each having a substantially semicircular annular plate shape, and these two parts are combined to form a substantially circular annular plate shape as a whole (see FIG. 4, etc.). However, as shown in FIG. 20, the adapter 110A6 provided in the composite molecular pump 1A according to the sixth modified example includes twelve parts each having a substantially 1 / 12 circular annular plate shape, and these twelve parts are combined to form a substantially circular annular plate shape as a whole.

[0153] In this case, unlike the first embodiment, a single mounting structure for mounting the compound molecular pump 1A6 to the vacuum chamber 70 is configured by fixing the base portion 14 of the mounting portion of the compound molecular pump 1A6 to the flange portion 72 of the vacuum chamber 70 by a combination of the first cut-out portion 103A, the arm portion 114, the abutting portion 115, the bolt 15, and the nut 16. The arm portion 114 of each of these mounting structures is configured to leave a sufficient space around it when mounted.

[0154] Even when configured in this manner, as in the case of embodiment 1, it is possible to reliably mitigate the impact torque applied to the vacuum chamber 70 in the event of an abnormality, and it is possible to provide a composite molecular pump that does not require a long development period or increase in manufacturing costs.

[0155] As shown in the first embodiment, the fifth modification, and the sixth modification, the adapter may be configured with any number of parts as long as it has a generally annular plate shape as a whole. That is, the adapter may be configured with a single part, or may be divided into two or more parts. The number of parts that make up the adapter can be changed as appropriate based on factors such as the required level of impact torque absorption capacity (i.e., the required length of the arm portion), ease of installation, and minimizing an increase in the number of parts.

[0156] <Embodiment 2> Fig. 21 is a schematic cross-sectional view showing a state in which a compound molecular pump according to embodiment 2 is attached to a vacuum chamber. Fig. 22 is a schematic plan view of the casing body and rotor shown in Fig. 21 as seen along line XXII-XXII shown in Fig. 21, and Fig. 22 shows only the casing body and rotor. First, with reference to Figs. 21 and 22, the general configuration of a compound molecular pump 1B according to this embodiment will be described.

[0157] 21, in the compound molecular pump 1B according to this embodiment, a pump case 10B is composed of a casing body 100B, a base 20, and a thread groove vacuum pump portion stator 31 of the stator 30. That is, the compound molecular pump 1B does not include a part such as the adapter 110A that is included in the compound molecular pump 1A according to embodiment 1, and in this respect the configuration thereof is mainly different from that of the compound molecular pump 1A. The compound molecular pump 1B has a mounting portion for mounting the compound molecular pump 1B to the vacuum chamber 70, and the mounting portion is provided on the pump case 10B.

[0158] The compound molecular pump 1B according to this embodiment is fixed to the vacuum chamber 70 using bolts 15 and nuts 16 as fixing devices, similar to the compound molecular pump 1A according to the first embodiment.

[0159] 21 and 22 , casing main body 100B has a generally cylindrical shape and is made of, for example, a metal member, and includes a body portion 101, a flange portion 102B, a plurality of through-hole-like cutout portions 103B, a plurality of arm portions 104, and a plurality of stopper portions 105. One axial end of body portion 101 (i.e., the upper end of pump case 10B) is provided with intake port 13. Flange portion 102B is the substantial portion of the portion that surrounds intake port 13 and protrudes outward from the one end of body portion 101, excluding arm portions 104 and stopper portions 105, and alone constitutes base portion 14, which is the main portion of the mounting part.

[0160] Flange portion 102B includes a first main surface 102a that faces the vacuum chamber 70 in the attached state, and a second main surface 102b (see FIGS. 24 to 26) that faces the opposite side from the vacuum chamber 70 (i.e., the body portion 101 side) in the attached state. As a result, the axial end surface 14a of base portion 14 that faces the vacuum chamber 70 in the attached state is defined by first main surface 102a of flange portion 102B.

[0161] The plurality of cutouts 103B are arranged side by side at a distance from one another along the circumferential direction of the flange portion 102B. Each of the plurality of cutouts 103B is configured as an elongated hole extending along the circumferential direction of the flange portion 102B, and penetrates the flange portion 102B along the axial direction of the casing body 100B so as to reach both the first main surface 102a and the second main surface 102b of the flange portion 102B.

[0162] The plurality of arm portions 104 are provided corresponding to the plurality of cutout portions 103B described above, respectively. Each of the plurality of arm portions 104 extends so as to protrude in the circumferential direction of the flange portion 102B from the wall surface of the flange portion 102B at a portion that defines the corresponding cutout portion 103B, and is thereby accommodated in the cutout portion 103B.

[0163] The plurality of stopper portions 105 are provided corresponding to the plurality of arm portions 104. Each of the plurality of stopper portions 105 is located at the tip of the corresponding arm portion 104, and each of the plurality of stopper portions 105 is provided with a hole portion 105a that penetrates along the axial direction of the casing main body 100B. The hole portion 105a provided in each of the plurality of stopper portions 105 is used when attaching the composite molecular pump 1B to the vacuum chamber 70.

[0164] Here, in the composite molecular pump 1B according to this embodiment, the aforementioned cut-out portion 103B, arm portion 104, stop portion 105, bolt 15, and nut 16 are provided in correspondence with one another, and a combination of these cut-out portion 103B, arm portion 104, stop portion 105, bolt 15, and nut 16 fixes the base portion 14 of the mounting portion of the composite molecular pump IB to the flange portion 72 of the vacuum chamber 70, thereby forming one mounting structure for mounting the composite molecular pump 1B to the vacuum chamber 70. A plurality of these mounting structures are provided in a dotted row along the circumferential direction of the pump case 10B, and the composite molecular pump 1B and the vacuum chamber 70 are fixed to each other at each of these plurality of mounting structures, thereby enabling the composite molecular pump 1B to be firmly and reliably fixed to the vacuum chamber 70.

[0165] 21 and 22, an annular recess 107 extending along the circumferential direction of the flange portion 102B is provided in the first main surface 102a of the flange portion 102B that defines the axial end surface 14a of the base portion 14. A sealing member 60 made of an elastic material, such as an O-ring made of fluororubber, is disposed in this annular recess 107.

[0166] 21, the sealing member 60 is interposed between the casing main body 100B and the vacuum chamber 70 and sandwiched therebetween. Therefore, in the attached state, the gap between the casing main body 100B and the vacuum chamber 70 is sealed by the sealing member 60, thereby preventing air leakage from occurring in this area.

[0167] Fig. 23(A) is an enlarged plan view of region XXIIIA shown in Fig. 22 of the casing body shown in Fig. 22, and Fig. 23(B) is a cross-sectional view taken along line XXIIIB-XXIIIB shown in Fig. 23(A). Fig. 24 is an exploded view of essential parts for explaining the mounting structure of the composite molecular pump shown in Fig. 21 to a vacuum chamber. Figs. 25 and 26 are schematic cross-sectional views of the mounting structure shown in Fig. 24 and its vicinity taken along the circumferential and radial directions, respectively, in a mounted state. In particular, Fig. 26 is a schematic cross-sectional view taken along line XXVI-XXVI shown in Fig. 25. Next, with reference to Figs. 23(A), 23(B), and 24 to 26, the detailed configuration of the mounting portion of the composite molecular pump 1B according to this embodiment, the procedure for mounting the composite molecular pump 1B to a vacuum chamber 70, and the detailed configuration of the composite molecular pump 1B in a mounted state in the vacuum chamber 70 will be described.

[0168] 23(A), 23(B), 24 to 26 show only one of the mounting structures provided in a dotted row along the circumferential direction of casing main body 100B, or a portion included in that one mounting structure. The following description will focus on the configuration of this one mounting structure, but the configurations of the other mounting structures are similar. Also, in Figures 23(A), 23(B), and 25, the rotation direction DR1 of rotor 40 is shown schematically, and in Figure 23(A), the through-hole 72a provided in vacuum chamber 70 is shown by a dashed line to show the relative positional relationship between casing main body 100B and vacuum chamber 70 in the mounted state.

[0169] As shown in Figures 23(A) and 23(B), the end of the casing body 100B on the intake port 13 side mainly comprises a flange portion 102B as the base portion 14, a cut-out portion 103B, an arm portion 104, and a stop portion 105.

[0170] The arm portion 104 extends from the wall surface of the flange portion 102B at a portion that defines the cutout portion 103B, at one end of the flange portion 102B in the circumferential direction, so as to protrude in the circumferential direction of the flange portion 102B. The protruding direction of the arm portion 104 is opposite to the rotation direction DR1 of the rotor 40, and the wall surface at the one end of the circumferential direction of the flange portion 102B is the downstream wall surface along the rotation direction DR1 of the rotor 40 (the wall surface located on the left side in the drawing).

[0171] The stopper portion 105 extends along the thickness direction of the flange portion 102B, and in particular protrudes a predetermined height toward the upper side (i.e., the side where the vacuum chamber 70 is located when attached).

[0172] Furthermore, cutout portion 103B provided in casing main body 100B is formed to extend further in the opposite direction to rotation direction DR1 of rotor 40 than the portion that accommodates stopper portion 105. That is, of the wall surface of flange portion 102B at the portion that defines cutout portion 103B, the wall surface on the other end side of flange portion 102B in the circumferential direction, which is the wall surface on which arm portion 104 is provided, is the wall surface on the upstream side along rotation direction DR1 of rotor 40 (the wall surface located on the right side in the figure), and is positioned a predetermined distance away from stopper portion 105.

[0173] 23A and 24, the multiple holes 105a formed in the casing main body 100B are arranged to correspond to the multiple through holes 72a formed in the flange portion 72 of the vacuum chamber 70. Therefore, by arranging the casing main body 100B so as to face the flange portion 72 of the vacuum chamber 70, the multiple holes 105a and the multiple through holes 72a overlap, and by inserting bolts 15 into the multiple holes 105a and the multiple through holes 72a and screwing nuts 16 onto the bolts 15, the casing main body 100B is fixed to the vacuum chamber 70. In this way, the compound molecular pump 1B including the casing main body 100B is attached to the vacuum chamber 70.

[0174] The compound molecular pump 1B including the casing body 100B having the above-described configuration is attached to the vacuum chamber 70 according to the following procedure with reference to FIG.

[0175] First, the casing body 100B is positioned so that the first main surface 102a of the flange portion 102B faces the flange portion 72 of the vacuum chamber 70. At this time, the casing body 100B is positioned relative to the vacuum chamber 70 so that the hole 105a of the stopper portion 105 provided on the casing body 100B overlaps with the through-hole 72a provided in the flange portion 72 of the vacuum chamber 70, and the end of the stopper portion 105 contacts the end face of the flange portion 72 of the vacuum chamber 70.

[0176] Next, with this positioning performed, bolts 15 are inserted into the overlapping through-holes 72a and holes 105a, and nuts 16 are screwed onto the tips of the bolts 15. In this way, the casing body 100B is assembled to the vacuum chamber 70.

[0177] By going through the procedure described above, the flange portion 102B of the casing body 100B is fixed to the flange portion 72 of the vacuum chamber 70, thereby attaching the compound molecular pump 1B to the vacuum chamber 70.

[0178] When the compound molecular pump 1B is attached to the vacuum chamber 70, the mounting structure and its surroundings are configured as shown in FIGS.

[0179] That is, as shown in Figures 25 and 26, at the connection between the composite molecular pump 1B and the vacuum chamber 70, the flange portion 72 of the vacuum chamber 70 and the flange portion 102B of the casing body 100B are stacked from top to bottom along the axial direction of the casing body 100B, and the abutment portion 105 provided on the casing body 100B and the flange portion 72 of the vacuum chamber 70 are fastened together by bolts 15 and nuts 16 which serve as fixing devices.

[0180] In the composite molecular pump 1B according to this embodiment, the end of the stopper portion 105, which will be located on the vacuum chamber 70 side in the mounted state, is configured to protrude toward the vacuum chamber 70 beyond the axial end face 14a of the base portion 14, which is formed by the flange portion 102B of the casing main body 100B. As a result, in the mounted state, the axial end face 14a of the base portion 14 is not in contact with the vacuum chamber 70, and furthermore, the arm portion 104 is not in contact with the vacuum chamber 70 either. The only point in direct contact with the vacuum chamber 70 is the end face of the stopper portion 105 on the casing main body 100B facing the vacuum chamber 70 (i.e., the area surrounded by the dashed line indicated by symbol α in the figure). Therefore, the contact area of ​​the direct contact portion of the composite molecular pump 1B with the vacuum chamber 70 is minimized.

[0181] That is, a gap G is formed between the flange portion 72 of the vacuum chamber 70 and the base portion 14, and the size of this gap G is determined by the protruding height h of the stop portion 105 that protrudes from the axial end face 14a of the base portion 14 toward the vacuum chamber 70.

[0182] Even in this configuration, as in the case of the first embodiment, if some abnormality (such as an earthquake or the intake of a foreign object) occurs during operation of the compound molecular pump 1B and causes the rotor 40, which is rotating at high speed, to come into contact with another member such as the stator 30, a tensile load will be applied to the arm portion 104 in the direction of the arrow DR2 shown in the figure, and this tensile load will cause plastic deformation (tensile deformation) of the arm portion 104.

[0183] Furthermore, as described above, the stopper portion 105 provided at the tip of the arm portion 104 is located a predetermined distance away from the upstream wall surface of the flange portion 102B in the portion that defines the missing portion 103B, along the rotation direction DR1 of the rotor 40, thereby preventing the stopper portion 105 from coming into contact with other parts of the flange portion 102B.

[0184] Therefore, energy is consumed by the plastic deformation of the arm portion 104, which results in a significant reduction in the impact torque applied to the vacuum chamber 70. Furthermore, as described above, at this time, since the base portion 14 and the arm portion 104 are not in contact with the vacuum chamber 70, no friction occurs between them, and the energy is consumed substantially only by the plastic deformation of the arm portion 104.

[0185] Unlike energy consumption due to friction, energy consumption due to plastic deformation (tensile deformation) of the arm portion 104 can be specifically calculated at the design stage. That is, the amount of energy consumption due to plastic deformation of the arm portion 104 can be calculated in advance at the design stage based on the material and cross-sectional area of ​​the arm portion 104. Therefore, by appropriately selecting and adjusting the material and cross-sectional area of ​​the arm portion 104, it is possible to design in advance the amount of mitigation of the impact torque applied to the vacuum chamber 70 in the event of an abnormality.

[0186] Furthermore, if the generated impact torque is reduced by such a method, the amount of reduction can be calculated in advance, and therefore, compared to conventional known methods, it is possible to significantly reduce the number of times that the composite molecular pump needs to be designed, a prototype manufactured, and an experiment to reproduce an abnormality using the prototype is performed, thereby shortening the development period of the composite molecular pump and reducing the manufacturing cost.

[0187] Therefore, by using the composite molecular pump 1B according to this embodiment, it is possible to reliably reduce the impact torque applied to the vacuum chamber 70 in the event of an abnormality, and it is possible to provide a composite molecular pump without lengthening the development period or increasing the manufacturing cost. Furthermore, since the impact torque applied to the vacuum chamber 70 in the event of an abnormality can be known in advance, it becomes easier to design the strength of the vacuum chamber 70, and in this respect too, it is possible to prevent damage to the vacuum chamber 70.

[0188] <Embodiment 3> Fig. 27 is a schematic cross-sectional view showing a state in which a compound molecular pump according to Embodiment 3 is attached to a vacuum chamber. Fig. 28 is a schematic plan view of the casing body and rotor shown in Fig. 27 as viewed along line XXVIII-XXVIII in Fig. 27, with Fig. 28 illustrating only the casing body and rotor. Fig. 29 is a schematic plan view of the adapter shown in Fig. 27 as viewed along line XXIX-XXIX in Fig. 27, with Fig. 29 illustrating only the adapter. First, with reference to Figs. 27 to 29, the overall configuration of a compound molecular pump 1C according to this embodiment will be described. Note that the compound molecular pump 1C according to this embodiment differs from the compound molecular pump 1A according to Embodiment 1 only in the configuration of the attachment portion.

[0189] 27, in the compound molecular pump 1C according to this embodiment, similarly to the compound molecular pump 1A described above, a pump case 10C is composed of a casing body 100C, an adapter 110C, a base 20, and a thread groove vacuum pump portion stator 31 of the stator 30. The compound molecular pump 1C has a mounting portion for mounting the compound molecular pump 1C to the vacuum chamber 70, and the mounting portion is provided on the pump case 10C.

[0190] In the composite molecular pump 1C, the upper end of the pump case 10C, which will be located on the vacuum chamber 70 side when attached to the vacuum chamber 70, is equipped with a casing main body 100C including a body 101 and a first flange 102C described later, as well as an adapter 110C including a second flange 112C (see Figures 29 to 33) described later, and of these, the first flange 102C, the second flange 112C and the bolt 19 constitute the base portion 14 of the attachment portion.

[0191] The compound molecular pump 1C according to this embodiment is fixed to the vacuum chamber 70 by using bolts 18 as fixing devices. More specifically, a base portion 14 (described later) provided at the end portion on the upper end side of the pump case 10C is attached to the vacuum chamber 70 by using the bolts 18, thereby fixing the compound molecular pump 1C to the vacuum chamber 70.

[0192] Here, in the composite molecular pump 1C according to the present embodiment, similarly to the composite molecular pump 1A according to the first embodiment described above, of the casing body 100C and the adapter 110C, only the end face of the abutting portion 115 of the adapter 110C on the vacuum chamber 70 side comes into contact with the vacuum chamber 70 in the attached state, and thus the composite molecular pump 1C is directly fixed to the vacuum chamber 70 (see FIGS. 32 and 33).

[0193] However, in the compound molecular pump 1C, the position at which the adapter 110C is fixed to the casing main body 100C is different from the compound molecular pump 1A according to the first embodiment. That is, in the first embodiment, the first flange portion 102A of the casing main body 100A faces the vacuum chamber 70, and the adapter 110A is attached on the side opposite the first flange portion 102A from the side on which the vacuum chamber 70 is located. In contrast, in the present embodiment, the adapter 110C faces the vacuum chamber 70, and the casing main body 100C is attached on the side opposite the side on which the vacuum chamber 70 is located from the adapter 110C. Accordingly, the configuration of the attachment portion is also different. Details thereof will be described below.

[0194] 27 and 28 , a casing body 100C of the compound molecular pump 1C has a generally cylindrical shape and is made of, for example, a metal member, and includes a body 101, a first flange 102C, and a plurality of through-hole-like fixing holes 106b. An intake port 13 is provided at one axial end of the body 101. The first flange 102C is a substantial portion located so as to surround the intake port 13 and protrude outward from the one end of the body 101, and the fixing holes 106b are cut-out portions provided in that portion.

[0195] The first flange portion 102C includes a first main surface 102a that is positioned on the vacuum chamber 70 side when attached, and a second main surface 102b (see Figures 31 to 33) that is positioned on the opposite side from the vacuum chamber 70 side (i.e., the body portion 101 side) when attached.

[0196] The fixing holes 106b are arranged side by side at a distance from one another along the circumferential direction of the first flange portion 102C. Each of the fixing holes 106b penetrates the first flange portion 102C along the axial direction of the casing main body 100C so as to reach both the first main surface 102a and the second main surface 102b of the first flange portion 102C. The fixing holes 106b are used to fix an adapter 110C, which is configured separately from the casing main body 100C, to the casing main body 100C.

[0197] As shown in Figures 27 and 29, the adapter 110C of the compound molecular pump 1C has a generally annular plate shape and is made of, for example, a metal member. The adapter 110C includes multiple arm portions 114, multiple stop portions 115, a generally annular plate-shaped second flange portion 112C that forms the remaining substantial portion, multiple through-hole-shaped cutout portions 113C, and multiple through-hole-shaped fixing screw holes 116b. The adapter 110C has an opening 111 located inside the second flange portion 112C, and the opening 111 has a size that matches the intake port 13 provided in the casing main body 100C. When installed, this opening 111 forms a communication passage that connects the intake port 13 with the interior space of the vacuum chamber 70.

[0198] The second flange portion 112C includes a third main surface 112a that is positioned on the vacuum chamber 70 side in the attached state, and a fourth main surface 112b (see FIGS. 30 to 33, etc.) that is positioned on the opposite side from the vacuum chamber 70 in the attached state. The axis of the second flange portion 112C coincides with the rotation axis RA of the rotor 40 of the compound molecular pump 1C in the attached state.

[0199] The plurality of cutouts 113C are positioned side by side at a distance from one another along the circumferential direction of the adapter 110C. Each of the plurality of cutouts 113C is configured as an elongated hole extending along the circumferential direction of the adapter 110C, and penetrates the second flange portion 112C along the axial direction of the adapter 110C so as to reach both the third main surface 112a and the fourth main surface 112b of the second flange portion 112C.

[0200] The plurality of arm portions 114 are provided corresponding to the plurality of cutout portions 113C described above, respectively. Each of the plurality of arm portions 114 extends so as to protrude in the circumferential direction of the adapter 110C from the wall surface of the second flange portion 112C at a portion that defines the corresponding cutout portion 113C, and is thereby accommodated in the cutout portion 113C.

[0201] The plurality of stopper portions 115 are provided corresponding to the plurality of arm portions 114. Each of the plurality of stopper portions 115 is located at the tip of the corresponding arm portion 114, and each of the plurality of stopper portions 115 is provided with a screw hole portion 115b that penetrates along the axial direction of the adapter 110C. The screw hole portion 115b provided in each of the plurality of stopper portions 115 is used when attaching the compound molecular pump 1A to the vacuum chamber 70.

[0202] Each of the plurality of fixing screw holes 116b penetrates the second flange portion 112C along the axial direction of the adapter 110C so as to reach both the third main surface 112a and the fourth main surface 112b of the second flange portion 112C. These plurality of fixing screw holes 116b are used to fix the adapter 110C, which is configured separately from the casing main body 100C, to the casing main body 100C.

[0203] 27 , in the compound molecular pump 1C according to this embodiment, the adapter 110C is fixed to the casing main body 100C while being placed against the first main surface 102a of the first flange portion 102C of the casing main body 100C. That is, the casing main body 100C and the adapter 110C are secured together with the first main surface 102a and the fourth main surface 112b in contact with each other, and are secured together with the bolts 19. As a result, the first flange portion 102C of the casing main body 100C and the second flange portion 112C of the adapter 110C are substantially integrated, thereby constituting the base portion 14 of the mounting portion.

[0204] Therefore, when the composite molecular pump 1C is attached to the vacuum chamber 70, the second flange portion 112C of the adapter 110C is positioned on the vacuum chamber 70 side when viewed from the first flange portion 102C of the casing body 100C, and as a result, the axial end surface 14a of the base portion 14 that faces the vacuum chamber 70 in this attached state is defined by the third main surface 112a of the second flange portion 112C.

[0205] Here, in the composite molecular pump 1C according to this embodiment, the aforementioned cut-out portion 113C, arm portion 114, stopper portion 115, and bolt 18 are provided in correspondence with one another, and a combination of these cut-out portion 113C, arm portion 114, stopper portion 115, and bolt 18 fixes the base portion 14 of the mounting portion of the composite molecular pump IC to the flange portion 72 of the vacuum chamber 70, thereby forming one mounting structure for mounting the composite molecular pump 1C to the vacuum chamber 70. A plurality of these mounting structures are provided in a dotted row along the circumferential direction of the pump case 10C, and the composite molecular pump 1C and the vacuum chamber 70 are fixed to each other at each of these plurality of mounting structures, thereby enabling the composite molecular pump 1C to be firmly and reliably fixed to the vacuum chamber 70.

[0206] 27 and 29, an annular recess 117 extending along the circumferential direction of the adapter 110C is provided in the third main surface 112a of the adapter 110C, which defines the axial end surface 14a of the base portion 14. A sealing member 60 made of an elastic material, such as an O-ring made of fluororubber, is disposed in this annular recess 117.

[0207] 27, in the attached state, the sealing member 60 is interposed between the adapter 110C and the vacuum chamber 70 and sandwiched therebetween. Therefore, in the attached state, the gap between the adapter 110C and the vacuum chamber 70 is sealed by the sealing member 60, thereby preventing air leakage from occurring in this portion.

[0208] 27 and 28, the first main surface 102a of the first flange portion 102C is provided with an annular recess 107 extending in the circumferential direction of the first flange portion 102C. A sealing member 61 made of an elastic material, such as an O-ring made of fluororubber, is disposed in the annular recess 107.

[0209] As a result, in the attached state, the sealing member 61 is interposed between the casing main body 100C and the adapter 110C and sandwiched therebetween, as shown in Fig. 27. Therefore, in the attached state, the gap between the casing main body 100C and the adapter 110C is sealed by the sealing member 61, thereby preventing air leakage from this portion.

[0210] FIG. 30(A) is an enlarged plan view of region XXXA shown in FIG. 29 of the adapter shown in FIG. 29, and FIG. 30(B) is a cross-sectional view taken along line XXXB-XXXB shown in FIG. 30(A). FIG. 31 is an exploded view of essential parts for explaining the mounting structure of the composite molecular pump shown in FIG. 27 to a vacuum chamber. Also, FIGS. 32 and 33 are schematic cross-sectional views taken along the circumferential and radial directions, respectively, of the mounting structure shown in FIG. 31 and its vicinity in the mounted state. In particular, FIG. 33 is a schematic cross-sectional view taken along line XXXIII-XXXIII shown in FIG. 32. Next, with reference to FIGS. 30(A), 30(B), and 31 to 33, the detailed configuration of the mounting portion of the composite molecular pump 1C according to this embodiment, the procedure for mounting the composite molecular pump 1C to a vacuum chamber 70, and the detailed configuration of the composite molecular pump 1C in the mounted state mounted to the vacuum chamber 70 will be described.

[0211] 30(A), 30(B), 31 to 33 show only one of the mounting structures provided in a dotted row along the circumferential direction of the casing body 100C, or a portion included in that one mounting structure. The following description focuses on the configuration of this one mounting structure, but the configurations of the other mounting structures are basically the same. Also, in Figures 30(A), 30(B), and 32, the rotation direction DR1 of the rotor 40 is shown schematically. In Figure 30(A), the through-hole 72a in the vacuum chamber 70 is shown by a dashed line, and the fixing hole 106b in the casing body 100C is shown by a broken line to show the relative positional relationship between the adapter 110C, the casing body 100C, and the vacuum chamber 70 in the attached state.

[0212] As shown in Figures 30(A) and 30(B), the adapter 110C mainly includes a second flange portion 112C as the base portion 14, a cut-out portion 113C, an arm portion 114, a stop portion 115, and a fixing screw hole 116b.

[0213] The arm portion 114 extends from the wall surface of the second flange portion 112C at a portion that defines the cutout portion 113C, at one end of the second flange portion 112C in the circumferential direction, so as to protrude in the circumferential direction of the second flange portion 112C. The protruding direction of the arm portion 114 is opposite to the rotational direction DR1 of the rotor 40, and the wall surface at the one end of the circumferential direction of the second flange portion 112C is the downstream wall surface (the wall surface located on the left side in the drawing) along the rotational direction DR1 of the rotor 40.

[0214] The stopper portion 115 extends along the thickness direction of the second flange portion 112C, and in particular protrudes a predetermined height toward its upper side (i.e., the side where the vacuum chamber 70 is located when attached).

[0215] Furthermore, cutout portion 113C provided in adapter 110C is formed to extend further in the opposite direction to rotational direction DR1 of rotor 40 than the portion that accommodates stopper portion 115. That is, of the wall surface of second flange portion 112C at the portion that defines cutout portion 113C, the wall surface on the other end side in the circumferential direction of second flange portion 112C, which is the wall surface on which arm portion 114 is provided, is positioned a predetermined distance away from stopper portion 115.

[0216] 30(A) and 31 , the plurality of fixing screw holes 116b provided in the second flange portion 112C of the adapter 110C serving as the base portion 14 are arranged to correspond to the plurality of fixing holes 106b provided in the first flange portion 102C of the casing main body 100C serving as the base portion 14. Therefore, when the second flange portion 112C of the adapter 110C is fitted to the first flange portion 102C of the casing main body 100C, the plurality of fixing screw holes 116b and the plurality of fixing holes 106b overlap, and by screwing bolts 19 into the plurality of fixing screw holes 116b through the plurality of fixing holes 106b, the adapter 110C is fixed to the casing main body 100C.

[0217] Furthermore, the multiple screw holes 115b provided in the adapter 110C are arranged to correspond to the multiple through holes 72a provided in the flange portion 72 of the vacuum chamber 70. Therefore, when the adapter 110C is fixed to the casing main body 100C, the adapter 110C is further positioned to face the flange portion 72 of the vacuum chamber 70, so that the multiple screw holes 115b and the multiple through holes 72a overlap, and the bolts 18 are screwed into the multiple screw holes 115b through the multiple through holes 72a, thereby fixing the adapter 110C to the vacuum chamber 70. In this way, the composite molecular pump 1C including the casing main body 100C and the adapter 110C is attached to the vacuum chamber 70.

[0218] By using the adapter 110C having the configuration described above, the compound molecular pump 1C is attached to the vacuum chamber 70 according to the following procedure with reference to FIG.

[0219] In the first step, the adapter 110C is assembled to the casing main body 100C. Specifically, first, the fourth main surface 112b of the adapter 110C is aligned with the first main surface 102a of the first flange portion 102A of the casing main body 100C. At this time, the adapter 110C is positioned relative to the casing main body 100C so that the multiple fixing screw holes 116b provided in the adapter 110C overlap the multiple fixing holes 106b provided in the first flange portion 102A of the casing main body 100C. Next, with the adapter 110C positioned in this state, the bolts 17 are threaded into the fixing screw holes 116b. This completes the assembly of the adapter 110C to the casing main body 100C.

[0220] In the second step, the adapter 110C is assembled to the vacuum chamber 70. Specifically, with the adapter 110C assembled to the casing main body 100C, the adapter 110C is positioned so that the third main surface 112a of the second flange portion 112C faces the flange portion 72 of the vacuum chamber 70. At this time, the adapter 110C is positioned relative to the vacuum chamber 70 so that the screw hole portion 115b of the stopper portion 115 provided on the adapter 110C overlaps with the through hole 72a provided in the flange portion 72 of the vacuum chamber 70, and the end of the stopper portion 115 contacts the end surface of the flange portion 72 of the vacuum chamber 70. Next, with the adapter 110C positioned in this manner, the bolt 18 is screwed into the screw hole portion 115b. This completes the assembly of the adapter 110C to the vacuum chamber 70.

[0221] By going through the procedure described above, the first flange portion 102C of the casing body 100C is fixed to the flange portion 72 of the vacuum chamber 70 via the adapter 110C, thereby attaching the composite molecular pump 1C to the vacuum chamber 70.

[0222] When the compound molecular pump 1C is attached to the vacuum chamber 70, the mounting structure and its surroundings are configured as shown in FIGS.

[0223] That is, as shown in Figures 32 and 33, at the connection between the composite molecular pump 1C and the vacuum chamber 70, the flange portion 72 of the vacuum chamber 70, the second flange portion 112C of the adapter 110C, and the first flange portion 102C of the casing body 100C are stacked and positioned in this order from top to bottom along the axial direction of the casing body 100C, and the second flange portion 112C of the adapter 110C and the first flange portion 102A of the casing body 100C are fixed by bolts 19, and the stopper portion 115 provided on the adapter 110C and the flange portion 72 of the vacuum chamber 70 are fixed by bolts 18 serving as fixing devices.

[0224] In the composite molecular pump 1C according to this embodiment, the end of the stopper portion 105, which will be located on the vacuum chamber 70 side in the attached state, is configured to protrude toward the vacuum chamber 70 beyond the axial end face 14a of the base portion 14, which is formed by the second flange portion 112C of the adapter 110C. As a result, in the attached state, the axial end face 14a of the base portion 14 is not in contact with the vacuum chamber 70, and furthermore, the arm portion 114 is not in contact with the vacuum chamber 70 either. The only point in direct contact with the vacuum chamber 70 is the end face of the stopper portion 115 provided on the adapter 110C on the vacuum chamber 70 side (i.e., the area surrounded by the dashed line indicated by symbol α in the figure). Therefore, the contact area of ​​the direct contact point of the composite molecular pump 1C with the vacuum chamber 70 is minimized.

[0225] That is, a gap G is formed between the flange portion 72 of the vacuum chamber 70 and the base portion 14, and the size of this gap G is determined by the protruding height h of the stop portion 115 that protrudes from the axial end face 14a of the base portion 14 toward the vacuum chamber 70.

[0226] Even with this configuration, as in the first embodiment, if some abnormality (such as an earthquake or the intake of a foreign object) occurs during operation of the compound molecular pump 1C and causes the rotor 40, which is rotating at high speed, to come into contact with another member such as the stator 30, a tensile load will be applied to the arm portion 114 in the direction of arrow DR2 shown in the figure, and this tensile load will cause plastic deformation (tensile deformation) of the arm portion 114.

[0227] Furthermore, as described above, the stopper portion 115 provided at the tip of the arm portion 114 is located a predetermined distance away from the upstream wall surface of the second flange portion 112C in the direction of rotation DR1 of the rotor 40, at the portion of the wall surface that defines the missing portion 113C, thereby preventing the stopper portion 115 from coming into contact with other parts of the second flange portion 112C.

[0228] Therefore, energy is consumed by the plastic deformation of the arm portion 114, resulting in a significant reduction in the impact torque applied to the vacuum chamber 70. Furthermore, as described above, at this time, since the base portion 14 and the arm portion 114 are not in contact with the vacuum chamber 70, no friction occurs between them, and the energy is consumed substantially only by the plastic deformation of the arm portion 114.

[0229] Unlike energy consumption due to friction, energy consumption due to plastic deformation (tensile deformation) of the arm portion 114 can be specifically calculated at the design stage. That is, the amount of energy consumption due to plastic deformation of the arm portion 114 can be calculated in advance at the design stage based on the material and cross-sectional area of ​​the arm portion 114. Therefore, by appropriately selecting and adjusting the material and cross-sectional area of ​​the arm portion 114, it is possible to design in advance the amount of mitigation of the impact torque applied to the vacuum chamber 70 in the event of an abnormality.

[0230] Furthermore, if the generated impact torque is reduced by such a method, the amount of reduction can be calculated in advance, and therefore, compared to conventional known methods, it is possible to significantly reduce the number of times that the composite molecular pump needs to be designed, a prototype manufactured, and an experiment to reproduce an abnormality using the prototype is performed, thereby shortening the development period of the composite molecular pump and reducing the manufacturing cost.

[0231] Therefore, by using the composite molecular pump 1C according to this embodiment, it is possible to reliably reduce the impact torque applied to the vacuum chamber 70 in the event of an abnormality, and it is possible to provide a composite molecular pump without lengthening the development period or increasing the manufacturing cost. Furthermore, since the impact torque applied to the vacuum chamber 70 in the event of an abnormality can be known in advance, it becomes easier to design the strength of the vacuum chamber 70, and in this respect too, it is possible to prevent damage to the vacuum chamber 70.

[0232] <Additional Notes> The characteristic configurations of the molecular pumps disclosed in the above-described first to third embodiments and their modifications can be summarized as follows.

[0233] [Supplementary Note 1] A molecular pump provided with an attachment part for a vacuum chamber, comprising: a pump case including a cylindrical body having an intake port at one axial end of the body, the attachment part being provided so as to surround the intake port; a stator held immovably by the pump case; a rotor rotatably supported by the pump case; and a rotation drive mechanism for rotationally driving the rotor, wherein the attachment part includes: a base part having an axial end face that faces the vacuum chamber in an attachment state where the attachment part is attached to the vacuum chamber; a stopper part that is fastened to the vacuum chamber in the attachment state; an arm part connecting the base part and the stopper part; and a fixture for fixing the stopper part to the vacuum chamber, wherein an end part of the stopper part that will be located on the vacuum chamber side in the attachment state protrudes toward the vacuum chamber beyond the axial end face of the base part, so that the base part and the arm part are not in contact with the vacuum chamber in the attachment state.

[0234] [Supplementary Note 2] The molecular pump according to Supplementary Note 1, wherein the mounting portion has a first flange portion located at the one end of the body portion and an adapter configured separately from the first flange portion, the adapter includes a second flange portion fixed to the first flange portion, the base portion is configured by the first flange portion and the second flange portion, the arm portion and the stop portion are provided on the adapter, the second flange portion is fixed to the first flange portion while being placed against a main surface of the first flange portion located on the body portion side so that it is located on the opposite side to the vacuum chamber side as seen from the first flange portion in the attached state, thereby the axial end surface is defined by the first flange portion, the first flange portion is provided with a first cutout portion that penetrates along the axial direction of the body portion, and the stop portion is inserted into the first cutout portion.

[0235] [Appendix 3] The molecular pump according to Appendix 2, wherein the second flange portion is provided with a second cutout portion that penetrates along the axial direction of the body portion and includes a portion facing the first cutout portion, and the arm portion and a portion of the stopper portion are housed in the second cutout portion.

[0236] [Appendix 4] The molecular pump according to Appendix 1, wherein the mounting portion is located at the one end of the body portion and includes a flange portion that defines the axial end surface, and the base portion, the arm portion, and the abutment portion are all provided on the flange portion.

[0237] [Appendix 5] The molecular pump according to appendix 4, wherein the flange portion has a cutout portion that penetrates along the axial direction of the body portion, and the arm portion and a part of the stopper portion are housed in the cutout portion.

[0238] [Supplementary Note 6] The molecular pump according to Supplementary Note 1, wherein the mounting portion has a first flange portion located at the one end of the body portion and an adapter configured separately from the first flange portion, the adapter includes a second flange portion fixed to the first flange portion, the base portion is configured by the first flange portion and the second flange portion, the arm portion and the abutment fastening portion are provided on the adapter, and the second flange portion is fixed to the first flange portion in a state where it is placed against a main surface of the first flange portion located opposite to the main surface located on the body portion side so that it is located on the vacuum chamber side when viewed from the first flange portion in the attached state, thereby the axial end surface is defined by the second flange portion.

[0239] [Appendix 7] The molecular pump according to appendix 6, wherein the second flange portion has a cutout portion that penetrates along the axial direction of the body portion, and the arm portion and a part of the stopper portion are housed in the cutout portion.

[0240] [Supplementary Note 8] The molecular pump according to any one of Supplementary Notes 1 to 7, wherein the arm portion extends along the circumferential direction or the radial direction of the body portion.

[0241] [Appendix 9] The molecular pump according to any one of appendices 1 to 8, wherein a plurality of mounting structures including the arm portion, the stopper portion, and the fixing device are provided in a dotted row along the circumferential direction of the body portion.

[0242] [Appendix 10] A molecular pump according to any one of Appendices 1 to 9, wherein the mounting portion further includes a sealing member made of an elastic body arranged on the axial end surface, and in the mounted state, the sealing member is sandwiched between the axial end surface and the vacuum chamber, thereby sealing a gap between the pump case and the vacuum chamber.

[0243] <Other forms, etc.>

[0244] In the above-described first to third embodiments and their modifications, the present invention has been described as being applied to a compound molecular pump having a turbomolecular pump section and a thread groove vacuum pump section, but the present invention can also be applied to a turbomolecular pump alone that does not have a thread groove vacuum pump section, or to a thread groove vacuum pump alone that does not have a turbomolecular pump section.

[0245] Furthermore, the characteristic configurations disclosed in the above-described first to third embodiments and their modifications can be combined with each other without departing from the spirit of the present invention.

[0246] As such, the above-described embodiments and their modifications disclosed herein are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims.

[0247] 1A, 1A1 to 1A6, 1B, 1C Compound molecular pump, 2 Turbo molecular pump section, 3 Thread groove vacuum pump section, 10A, 10A1 to 10A6, 10B, 10C Pump case, 100A, 100A1 to 100A4, 100B, 100C Casing body, 101 Body section, 102A First flange section, 102B Flange section, 102C First flange section, 102a First main surface, 102b Second main surface, 103A First cutout section, 103B Cutout section, 104 Arm section, 105 Stopper section, 105a Hole section, 106a Fixing screw hole, 106b Fixing hole, 107 Annular recess, 110A, 110A1 to 110A6, 110C Adapter, 111 Opening, 112A, 112C second flange portion, 112a third main surface, 112b fourth main surface, 113A second cutout portion, 113C cutout portion, 114 arm portion, 115 stop portion, 115a hole portion, 115b screw hole portion, 116b fixing screw hole, 116a fixing hole, 117 annular recess, 13 intake port, 14 base portion, 14a axial end face, 15 bolt, 16 nuts, 17 to 19 bolt, 20 pedestal, 21 exhaust port, 30 stator, 31 thread groove vacuum pump portion stator, 31a thread groove portion, 32 stationary blade, 33 spacer and support member, 40 rotor, 41 rotor body, 41a upper rotor portion, 41b lower rotor portion, 42 moving blade, 50 rotation drive mechanism, 51 Output shaft, 52 housing, 60, 61 sealing member, 70 vacuum chamber, 71 body portion, 71a opening portion, 72 flange portion, 72a through hole, h protrusion height, G gap, RA rotation shaft.

Claims

1. A molecular pump having an attachment part for a vacuum chamber, comprising: a pump case including a cylindrical body having an intake port at one axial end of the body, the attachment part being provided to surround the intake port; a stator held immovably by the pump case; a rotor rotatably supported by the pump case; and a rotation drive mechanism for rotating the rotor, wherein the attachment part includes: a base part having an axial end face that faces the vacuum chamber when the attachment part is attached to the vacuum chamber; a stopper part that is fastened to the vacuum chamber in the attached state; an arm part connecting the base part and the stopper part; and a fixture for fixing the stopper part to the vacuum chamber, wherein the end of the stopper part that will be located on the vacuum chamber side in the attached state protrudes toward the vacuum chamber beyond the axial end face of the base part, so that the base part and the arm part are not in contact with the vacuum chamber in the attached state.

2. A molecular pump as claimed in claim 1, wherein the mounting portion has a first flange portion located at one end of the body portion and an adapter formed separately from the first flange portion, the adapter includes a second flange portion fixed to the first flange portion, the base portion is formed by the first flange portion and the second flange portion, the arm portion and the stopper portion are provided on the adapter, the second flange portion is fixed to the first flange portion while being placed against a main surface of the first flange portion located on the body portion side so that it is located on the opposite side to the vacuum chamber side as seen from the first flange portion in the mounted state, and the axial end surface is defined by the first flange portion, the first flange portion is provided with a first notch portion that passes through along the axial direction of the body portion, and the stopper portion is inserted into the first notch portion.

3. A molecular pump as described in claim 2, wherein the second flange portion is provided with a second notch that penetrates along the axial direction of the body portion and includes a portion facing the first notch, and the arm portion and a portion of the stopper portion are housed in the second notch.

4. A molecular pump as set forth in claim 1, wherein the mounting portion is located at one end of the body portion and includes a flange portion that defines the axial end surface, and the base portion, the arm portion, and the stop portion are all provided on the flange portion.

5. A molecular pump as set forth in claim 4, wherein the flange portion has a cutout portion that penetrates along the axial direction of the body portion, and the arm portion and a part of the stopper portion are housed in the cutout portion.

6. A molecular pump as described in claim 1, wherein the mounting portion has a first flange portion located at the one end of the body portion and an adapter configured separately from the first flange portion, the adapter includes a second flange portion fixed to the first flange portion, the base portion is configured by the first flange portion and the second flange portion, the arm portion and the abutment portion are provided on the adapter, and the second flange portion is fixed to the first flange portion while being placed against a main surface of the first flange portion located opposite to the main surface located on the body portion side, so that the second flange portion is located on the vacuum chamber side when viewed from the first flange portion in the mounted state, thereby defining the axial end surface by the second flange portion.

7. A molecular pump as set forth in claim 6, wherein the second flange portion is provided with a cutout portion that penetrates along the axial direction of the body portion, and the arm portion and a part of the stopper portion are housed in the cutout portion.

8. A molecular pump according to any one of claims 1 to 7, wherein the arm portion extends along the circumferential direction or the radial direction of the body portion.

9. A molecular pump according to any one of claims 1 to 8, wherein a plurality of mounting structures including the arm portion, the stopper portion and the fixing device are provided in a dotted row along the circumferential direction of the body portion.

10. A molecular pump as described in any one of claims 1 to 9, wherein the mounting portion further includes a sealing member made of an elastic material disposed on the axial end face, and in the mounted state, the sealing member is sandwiched between the axial end face and the vacuum chamber, thereby sealing the gap between the pump case and the vacuum chamber.

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