Vacuum Pump

Abstract

A vacuum pump capable of suppressing the generation of deposits caused by exhaust gas is provided. The vacuum pump comprises: a pump unit (10b) having a shaft (13), a rotor (11) arranged on the outer peripheral side of the shaft (13), and a stator (21) arranged on the outer peripheral side of the rotor (11), a flow path of exhaust gas from the pump unit (10b) to an exhaust port (9), and a shielding unit (24) for suppressing contact of the exhaust gas with the shaft (13) in the flow path. Furthermore, the end of the shielding unit (24) has a surface facing the rotor (11).

Description

Technical Field

[0001] The present invention relates to a vacuum pump. Background Art

[0002] In some turbomolecular pumps, a protective component is replaceably provided on the exhaust pipe for exhausting gas from the pump unit, thereby suppressing the accumulation of reaction products on the gas contact surface (wall surface) where deposits are easily attached (for example, see Patent Document 1). The protective component is fixed to the base via a heat insulator, and due to radiation from the rotor cylinder and the stator, the temperature is higher than when it is directly fixed to the base.

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-2856.

[0004] The protective component in the above-mentioned turbomolecular pump has a shape along the shape of the base wall surface, and its upper end is separated from the opposing rotor. Therefore, the exhaust gas enters between the rotor and the shaft stator, and between the protective component and the shaft stator from the gap between the protective component and the rotor. The exhaust gas may come into contact with a portion with a lower temperature (such as the wall surface of the shaft stator extending from the head). For this reason, it is possible that components of the exhaust gas are separated and deposits are generated in this portion. Summary of the invention

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to obtain a vacuum pump that suppresses the occurrence of deposits caused by exhaust gas.

[0006] The vacuum pump of the present invention comprises: a pump part having a shaft part, a rotor arranged on the outer circumference of the shaft part, and a stator arranged on the outer circumference of the rotor, a flow path of exhaust gas from the pump part to an exhaust port, and a shielding part for suppressing the exhaust gas from contacting the shaft part in the flow path. Furthermore, an end of the shielding part has a surface facing the rotor.

[0007] According to the present invention, it is possible to obtain a vacuum pump that suppresses the occurrence of deposits due to exhaust gas.

[0008] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a diagram showing the internal structure of the vacuum pump according to Embodiment 1 of the present invention.

[0010] Figure 2 Yes Description Figure 1 A diagram showing details of the shape of the shielding portion.

[0011] Figure 3 This is a diagram for explaining the details of the shielding portion in the vacuum pump according to Embodiment 2 of the present invention.

[0012] Figure 4 This is a plan view showing an example of a groove structure provided on the surface of a shielding portion in the vacuum pump described in Embodiment 3.

[0013] Description of Reference Numerals

[0014] 9…Exhaust port

[0015] 10b…Thread groove pump part (an example of a pump part)

[0016] 11, 52…Rotor

[0017] 13, 51… shaft

[0018] 21, 53… Stator (an example of a stator and a heating component)

[0019] 24, 58…Shielding

[0020] 24a…end

[0021] 24a1…face

[0022] 24a2…Slot structure

[0023] 24b…Middle

[0024] 31…Flow path

[0025] 54 ... gasket (an example of a heating component). DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0027] Implementation method 1.

[0028] Figure 1 This is a diagram showing the internal structure of the vacuum pump according to Embodiment 1 of the present invention. Figure 1 The vacuum pump shown in the figure has a turbomolecular pump section 10a, a thread groove pump section 10b at the rear stage thereof, and has a housing 1, a stator blade 2, a rotor blade 3a, a rotor inner cylinder section 3b, a rotor shaft 4, a bearing section 5, a motor section 6, an air intake port 7, a thread groove 8, and an exhaust port 9. The rotor blade 3a and the rotor inner cylinder section 3b constitute a rotor 11, and the rotor 11 is connected and fixed to the rotor shaft 4 by screw fixing or the like.

[0029] The housing 1 has a substantially cylindrical shape, and contains a rotor 11, a bearing 5, a motor 6, etc. in its internal space, and a multi-stage stator blade 2 is fixed to its inner circumference. The stator blade 2 is arranged at a predetermined elevation angle. The housing 1 and the stator blade 2 constitute the stator of the turbomolecular pump unit 10a.

[0030] In the casing 1, multiple stages of rotor blades 3a and multiple stages of stator blades 2 are alternately arranged in the height direction of the rotor shaft (rotor shaft direction). Each rotor blade 3a extends from the rotor inner cylinder portion 3b and has a predetermined elevation angle.

[0031] The bearing unit 5 is a bearing of the rotor shaft 4, for example, a magnetic suspension type bearing, and is provided with a sensor for detecting the displacement of the rotor shaft 4 in the axial direction and the radial direction, an electromagnet for suppressing the displacement of the rotor shaft 4 in the axial direction and the radial direction, etc. In addition, the bearing type of the bearing unit 5 is not limited to the magnetic suspension type. The motor unit 6 rotates the rotor shaft 4 using electromagnetic force.

[0032] The bearing 5 and the motor 6 are arranged in the hollow part of the shaft 13 (stator column). In this embodiment, the shaft 13 and the base 13a are integrated, and a cooling pipe 14 is provided in the base 13a, and a cooling medium such as water is conducted to the cooling pipe 14. For example, the shaft 13 (and the base 13a) are made of aluminum material with good thermal conductivity. As a result, the base 13a and the shaft 13 are cooled, and the electrical components such as the motor 6 operate normally.

[0033] The air inlet 7 is an upper opening of the housing 1, has a flange shape, and is connected to a cavity, etc., not shown. Due to thermal motion, etc., gas molecules fly from the cavity, etc. into the air inlet 7. The exhaust port 9 has a flange shape, and discharges gas molecules, etc., sent from the rotor blade 3a and the stator blade 2.

[0034] in addition, Figure 1 The vacuum pump shown is of a compound vane type having a screw groove pump portion 10b based on the screw groove 8 at the rear stage of a turbomolecular pump portion 10a based on the stator vane 2 and the rotor vane 3a described above. Alternatively, the vacuum pump may be of a full vane type.

[0035] like Figure 1 As shown, the thread groove pump unit 10 b includes a shaft 13 , a rotor 11 disposed on the outer periphery of the shaft 13 , and a stator 21 disposed on the outer periphery of the rotor 11 .

[0036] Figure 1 In the vacuum pump shown, the flow path of the gas to be exhausted (exhaust gas) is the flow path from the intake port 7 to the exhaust port 9, including the intake port 7, the space between the rotor 11 and the stator (the stator blade 2 and the housing 1) of the turbomolecular pump part 10a, the space between the stator 21 (specifically, the thread groove 8) and the rotor 11 (specifically, the rotor inner tube part 3b) of the thread groove pump part 10b, and the exhaust port 9.

[0037] A heater 22 is provided in the stator 21 of the thread groove pump unit 10b, and the stator 21 is heated by the heater 22. In addition, a heat insulating member 23 is provided between the stator 21 and the base 3b in a state of being in contact and sealed therebetween. As a result, the temperature of the outer peripheral side of the flow path from the outlet of the thread groove pump unit 10b of the final stage to the exhaust port 9 is high, and the occurrence of deposits caused by the exhaust gas is suppressed.

[0038] Furthermore, in this embodiment, the shielding portion 24 is connected to the stator 21. The shielding portion 24 is a substantially annular member having, for example, Figure 1 The shielding portion 24 is provided in the exhaust gas flow path 31 from the final stage screw groove pump portion 10 b to the exhaust port 9 in order to prevent the exhaust gas from coming into contact with the shaft portion 13 .

[0039] Figure 2 Yes Description Figure 1 FIG. 2 is a diagram showing details of the shape of the shielding portion 24.

[0040] For example Figure 2 As shown in the figure, the shielding portion 24 is configured such that its end 24a has a surface 24a1 opposite to the rotor 11, and the surface 24a1 and the rotor 11 are used to form a gas inflow suppression structure. In this embodiment, the gap between the end 24a of the shielding portion 24 (the surface 24a1 opposite to the above-mentioned rotor 11) and the rotor 11 (the bottom surface 11a opposite to the end 24a) is made to have a small width, thereby forming the gas inflow suppression structure. The width of the gap (that is, the distance between the surface 24a1 and the rotor 11) is, for example, about 1 to 1.5 mm. In addition, the width of the gap can be approximately the same as or smaller than the distance from the wall surface 13b of the shaft portion 13 to the inner peripheral surface of the shielding portion 24. In addition, the gas inflow suppression structure can also be, for example, a non-contact sealing structure.

[0041] In addition, in this embodiment, the shielding portion 24 includes an intermediate portion 24b extending along the wall surface 13b of the shaft portion 13 (here, vertically upward) to the end portion 24a, and the wall thickness TB of the intermediate portion 24b is formed to be smaller than the wall thickness TA of the end portion 24a. As a result, heat transfer from the stator 21 to the rotor 11 via the shielding portion 24 is suppressed, and the flow path area of ​​the flow path 31 is increased.

[0042] Furthermore, the shielding portion 24 is constructed and arranged so that the distance LS from the wall surface 13b of the shaft portion 13 to the outer peripheral surface of the end portion 24a of the shielding portion 24 is substantially the same as or shorter than the distance LR from the wall surface 13b of the shaft portion 13 to the outer peripheral surface of the rotor 11 (the portion in the thread groove pump portion 10b). As a result, the flow path near the outlet of the thread groove pump portion 10b is not blocked by the end portion 24a of the shielding portion 24.

[0043] Here, the interval between the shaft portion 13 and the shielding portion 24 and the interval between the shaft portion 13 and the rotor 11 may be substantially the same. In addition, the interval between the shaft portion 13 and the shielding portion 24 and the interval between the end portion 24a of the shielding portion 24 and the rotor 11 may be substantially the same. Thus, the above-mentioned gas inflow suppression structure is strengthened.

[0044] Here, the stator 21 is a heating component having a heater 22, and is made of, for example, aluminum, and faces the flow path 31. In the first embodiment, the shielding portion 24 is a single component, and is fixed to the stator 21 as the heating component by, for example, screwing, etc., in a manner that is directly joined to the stator 21 as the heating component (not via a heat insulating member). In addition, the shielding portion 24 may also be formed as a part of the stator 21 as the heating component (that is, in this case, the shielding portion 24 is a part of the heating component). Thus, heat is conducted from the stator 21 to the shielding portion 24, so that the temperature of the shielding portion 24 is managed to be higher than that of the shaft portion 13.

[0045] In addition, the temperature management of the stator 21 and the like is performed using a temperature sensor 25 provided in the stator 21 .

[0046] For example, the width of the gap between the end portion 24 a of the shielding portion 24 and the rotor 11 is set to about 1.5 mm, TA=about 4 mm, and LR=about 8 mm.

[0047] Next, the operation of the vacuum pump according to Embodiment 1 will be described.

[0048] The chamber and the like are connected to the air intake port 7 of the vacuum pump, and the motor unit 6 is operated according to the command from the control device (not shown), so that the rotor shaft 4 rotates and the rotor 11 also rotates. As a result, in the turbomolecular pump unit 10a, the gas molecules flying in through the air intake port 7 are advanced to the flow path by using the rotor blades 3a and the stator blades 2, and in the thread groove pump unit 10b of the subsequent stage, the gas molecules are discharged as exhaust gas to the flow path 31 by using the rotor 11 and the stator 21, and are discharged from the exhaust port 9 through the flow path 31.

[0049] Furthermore, the shielding portion 24 is heated by the stator 21 as a heating member and becomes hotter than the shaft portion 13, thereby suppressing the occurrence of deposits in the shielding portion 24. For example, the stator 21 is controlled to be at a temperature higher than about 100 degrees Celsius, and the base 13a is controlled to be at a temperature lower than about 60 degrees Celsius.

[0050] As described above, according to the first embodiment, the thread groove pump section 10b includes the shaft section 13, the rotor 11 disposed on the outer peripheral side of the shaft section 13, and the stator 21 disposed on the outer peripheral side of the rotor 11. The shielding section 24 is configured to suppress the exhaust gas from contacting the shaft section 13 in the flow path of the exhaust gas from the pump section 10b to the exhaust port 9. In addition, the end 24a of the shielding section 24 has a surface 24a1 facing the rotor 11.

[0051] Thus, the shielding portion 24 restricts the travel of the exhaust gas, and the exhaust gas is less likely to come into contact with the wall surface of the shaft portion 13 and the upper surface of the base portion 13 b , which are relatively low in temperature, thereby suppressing the generation of deposits caused by the exhaust gas.

[0052] Implementation method 2.

[0053] Figure 3 This is a diagram for explaining the details of the shielding portion in the vacuum pump according to Embodiment 2 of the present invention.

[0054] Figure 3 In the vacuum pump shown, as in the first embodiment, a rotor 52 is provided on the outer peripheral side of a shaft portion 51, and a stator 53 of a screw groove pump portion is provided on the outer peripheral side of the rotor 52. Furthermore, a gasket 54 joined to the stator 53 is provided, and a heater 55 is provided on the gasket 54. The shaft portion 51 is joined to a head portion 56, and as in the first embodiment, the head portion 56 is cooled, thereby also cooling the shaft portion 51. A heat insulating member 57 is provided between the gasket 54 as a heating member and the head portion 56. Here, since the gasket 54 is provided as a member different from the stator 53, in order to ensure strength at high temperatures, the gasket 54 may also be, for example, a stainless steel member.

[0055] Furthermore, in Embodiment 2, the shielding portion 58 is, for example, Figure 3 As shown, the shielding portion 58 is fixed to the spacer 54. The shielding portion 58 also has a substantially annular shape.

[0056] In Embodiment 2, shielding portion 58 is configured to have a gas inflow suppressing structure between its end and rotor 52. In this embodiment, a gap between the end of shielding portion 58 and rotor 52 is made to have a small width, thereby forming a gas inflow suppressing structure.

[0057] Furthermore, the shielding portion 58 includes an intermediate portion extending along the wall surface of the shaft portion 51 to the end portion of the shielding portion 58 , and the thickness of the intermediate portion is formed to be smaller than the thickness of the end portions.

[0058] Furthermore, the shielding portion 58 is constructed and arranged so that the distance from the wall surface of the shaft portion 51 to the outer peripheral surface of the end of the shielding portion 58 is approximately the same as or shorter than the distance from the wall surface of the shaft portion 51 to the outer peripheral surface of the rotor 52 (the portion in the thread groove pump portion).

[0059] The rest of the configuration and operation of the vacuum pump described in the second embodiment are the same as those in the first embodiment, and thus description thereof will be omitted.

[0060] Implementation method 3.

[0061] Figure 4 This is a plan view showing an example of the groove structure 24a2 provided on the surface 24a1 of the shielding portion 24 in the vacuum pump according to the third embodiment.

[0062] Figure 4 The groove structure 24a2 shown has a shape that suppresses the inflow of exhaust gas to the shaft portion 13, 51 side through the gap between the shielding portion 24 (surface 24a1) and the rotor 11, 52 (bottom surface 11a). The groove structure 24a2 is, for example, Figure 4 As shown, it is provided with a plurality of grooves inclined relative to the radial direction, and the wall surfaces (plane or curved surface) of the plurality of grooves are inclined at an angle and in a direction corresponding to the rotation direction of the rotors 11, 52, so that the exhaust gas (gas molecules, etc.) entering the grooves can be discharged to the outside of the rotors 11, 52 by utilizing the relative rotation of the shielding portion 24 and the rotors 11, 52.

[0063] In addition, the cross-sectional shape of each groove in the groove structure 24a2 is not particularly limited, for example, it is a substantially rectangular shape, a substantially triangular shape, or the like.

[0064] In addition, the shape of each groove in the groove structure 24a2 may be a linear shape or a spiral shape.

[0065] In addition, other structures and operations of the vacuum pump described in Embodiment 3 are the same as those in Embodiment 1 or Embodiment 2, and thus description thereof will be omitted.

[0066] In addition, various changes and modifications to the above-mentioned embodiments are self-evident to those skilled in the art. Such changes and modifications can be made as long as they do not deviate from the gist and scope of the subject matter and do not weaken the desired advantages. That is, such changes and modifications are considered to be included in the scope of protection of the rights.

[0067] For example, in the third embodiment, the groove structure 24a2 is provided on the surface 24a1 of the shielding portion 24, but the same groove structure may be provided on the bottom surface 11a of the rotor 11, or may be provided on both the surface 24a1 and the bottom surface 11a. In addition, the groove structure 24a2 may not be provided in the entire area of ​​the surface 24a1 of the shielding portion 24, but may be provided only in a portion on the outer circumference, for example.

[0068] In addition, for example, in the third embodiment, the purge gas may be introduced from the purge gas port 26 and passed to the gap between the rotor 11 and the shaft portion 13, and the purge gas may be discharged through the gap between the shielding portion 24 (surface 24a1) and the rotor 11, 52 (bottom surface 11a). In this case, the purge gas is effectively discharged to the exhaust gas flow path through the gap by the drag effect of the groove structure 24a2 and the like, so that the exhaust gas is less likely to contact the wall surface of the shaft portion 13 and the upper surface of the base portion 13b.

[0069] For example, in the above-mentioned Embodiments 1 and 2, the above-mentioned gas inflow suppression structure may be, for example, a labyrinth seal structure.

[0070] The present invention can be applied to a vacuum pump, for example.

Claims

1. A vacuum pump, have: A pump unit having a base, a shaft extending from the base, a rotor disposed on an outer peripheral side of the shaft, and a stator disposed on an outer peripheral side of the rotor; a flow path for exhaust gas from the aforementioned pump unit to the exhaust port; a shielding portion in the flow path for preventing the exhaust gas from contacting the shaft portion; The end of the shielding portion has a surface facing the rotor. The base and the shaft are thermally insulated from the stator and the shielding portion by a thermal insulation member disposed between the stator, the shielding portion, and the base and having a first contact surface in contact with the stator and a second contact surface in contact with the base. The first contact surface and the second contact surface are parts of the surface of the thermal insulation component perpendicular to the axial direction. A space is formed which is surrounded by the heat insulating member, the base and the shaft.

2. The vacuum pump according to claim 1, characterized in that The shielding portion includes an intermediate portion extending along the wall surface of the shaft portion to the end portion. The wall thickness of the middle portion is smaller than the wall thickness of the end portions.

3. The vacuum pump according to claim 1, characterized in that A distance from a wall surface of the shaft portion to an outer peripheral surface of an end portion of the shielding portion is less than or equal to a distance from the wall surface of the shaft portion to an outer peripheral surface of the rotor.

4. The vacuum pump according to claim 1, characterized in that At least one of the surface of the shielding portion and a surface of the rotor facing the surface has a groove structure for suppressing inflow of the exhaust gas toward the shaft portion through a gap between the shielding portion and the rotor.

5. The vacuum pump according to any one of claims 1 to 4, characterized in that further comprising a heating member having a heater, The shaft is cooled. The shielding portion is a member fixed to the heating component, or is a part of the heating component.

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