Vacuum pump

Abstract

To obtain a vacuum pump that suppresses the generation of deposit due to exhaust gas.SOLUTION: A vacuum pump includes a pump portion 10b that is equipped with a shaft portion 13, a rotor 11 disposed on an outer peripheral side of the shaft portion 13, and a stator 21 disposed on an outer peripheral side of the rotor 11, a channel of exhaust gas from the pump portion 10b to an exhaust port 9, and a shielding portion 24 that suppresses the contact of the exhaust gas to the shaft portion 13 in the channel. An end portion of the shielding portion 24 has a surface facing the rotor 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In some turbomolecular pumps, a replaceable protective member is provided on the exhaust pipe that discharges gas from the pump section, which prevents the deposition of reaction products on the gas-contacting surface (wall surface) where deposits tend to adhere (see, for example, Patent Document 1). This protective member is fixed to the base via a heat insulating material, and becomes hotter due to radiation from the rotor cylindrical section and the stator than if it were fixed directly to the base. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-2856 A Summary of the Invention [Problem to be solved by the invention]

[0004] The protective member in the above-mentioned turbomolecular pump has a shape that follows the shape of the base wall surface, but since its upper end is separated from the opposing rotor, exhaust gas can enter between the rotor and the shaft stator or between the protective member and the shaft stator through the gap between the protective member and the rotor, and the exhaust gas can come into contact with a relatively low temperature area (such as the wall surface of the shaft stator extending from the head), which can cause components of the exhaust gas to precipitate and form deposits in that area.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide a vacuum pump that suppresses the generation of deposits caused by exhaust gas. [Means for solving the problem]

[0006] The vacuum pump according to the present invention comprises:A head portion, a heat insulating member, and a Shaft and 、 The exhaust gas turbine comprises a pump section including a rotor arranged on the outer periphery of a shaft section and a stator arranged on the outer periphery of the rotor, an exhaust gas flow path from the pump section to an exhaust port, a shielding section that suppresses contact of the exhaust gas with the shaft section in the flow path, and a heating member including a heater. The shaft section is cooled. An end of the shielding section has a surface that faces the lower end surface of the rotor in the axial direction, and the shielding section is spaced from the shaft section and is a member fixed to the heating member or a part of the heating member. Furthermore, the insulating member is (a) disposed between the heating member and the shielding portion and the head portion, and (b) has a first end face facing the head portion and a second end face facing the heating member, the first end face including a contact portion in contact with the head portion and a non-contact portion not in contact with the head portion, and the second end face including a contact portion in contact with the heating member and a non-contact portion not in contact with the heating member. Effect of the Invention

[0007] According to the present invention, a vacuum pump that suppresses the generation of deposits caused by exhaust gas is obtained.

[0008] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an internal configuration of a vacuum pump according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining the details of the shape of the shielding portion in FIG. [Diagram 3] FIG. 3 is a diagram illustrating details of a shielding portion in a vacuum pump according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a top view showing an example of a groove structure provided on the surface of the shielding part in the vacuum pump according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] Embodiment 1

[0012] Fig. 1 is a diagram showing the internal configuration of a vacuum pump according to a first embodiment of the present invention. The vacuum pump shown in Fig. 1 includes a turbo molecular pump section 10a followed by a thread groove pump section 10b, and includes a casing 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 intake port 7, a thread groove 8, and an exhaust port 9. The rotor blades 3a and the rotor inner cylinder section 3b form a rotor 11, which is connected and fixed to the rotor shaft 4 by screws or the like.

[0013] The casing 1 has a generally cylindrical shape and houses the rotor 11, bearing unit 5, motor unit 6, etc. in its internal space, and has multiple stages of stator blades 2 fixed to its inner circumferential surface. The stator blades 2 are arranged at a predetermined elevation angle. The casing 1 and the stator blades 2 constitute the stator of the turbo molecular pump unit 10a.

[0014] 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 axial direction) inside the casing 1. Each rotor blade 3a extends from a rotor inner cylinder portion 3b and has a predetermined angle of elevation.

[0015] The bearing unit 5 is a bearing for the rotor shaft 4, for example a magnetic levitation type bearing, and includes a sensor for detecting axial and radial deviations of the rotor shaft 4, and an electromagnet for suppressing axial and radial deviations of the rotor shaft 4. The bearing type of the bearing unit 5 is not limited to the magnetic levitation type. The motor unit 6 rotates the rotor shaft 4 by electromagnetic force.

[0016] The bearing section 5 and the motor section 6 are disposed in a hollow section within the shaft section 13 (stator column). In this embodiment, the shaft section 13 is integrated with a base section 13a, which is provided with a cooling pipe 14 through which a coolant such as water is conducted. For example, the shaft section 13 (and the base section 13a) is made of an aluminum material with good thermal conductivity. This allows the base section 13a, and therefore the shaft section 13, to be cooled, ensuring proper operation of electrical components such as the motor section 6.

[0017] The intake port 7 is an opening at the top end of the casing 1, has a flange shape, and is connected to a chamber (not shown) or the like. Gas molecules fly into the intake port 7 from the chamber or the like due to thermal motion or the like. The exhaust port 9 has a flange shape, and exhausts gas molecules and the like sent from the rotor blades 3a and the stator blades 2.

[0018] 1 is a composite blade type having a screw groove pump section 10b formed by a screw groove 8 in the rear stage of a turbo molecular pump section 10a formed by the stator blades 2 and rotor blades 3a described above. The vacuum pump may be of a full blade type.

[0019] As shown in FIG. 1, this thread groove pump section 10b includes a shaft section 13, a rotor 11 arranged on the outer periphery of the shaft section 13, and a stator 21 arranged on the outer periphery of the rotor 11. As shown in FIG.

[0020] In the vacuum pump shown in FIG. 1, the flow path of the gas to be exhausted (exhaust gas) runs from the intake port 7 to the exhaust port 9, and includes the intake port 7, the space between the rotor 11 and the stator (the stator blades 2 and the casing 1) of the turbomolecular pump section 10a, the space between the stator 21 (specifically, the thread groove 8) and the rotor 11 (specifically, the rotor inner cylinder section 3b) of the thread groove pump section 10b, and the exhaust port 9.

[0021] A heater 22 is provided on the stator 21 of the thread groove pump section 10b, and the stator 21 is heated by the heater 22. A heat insulating member 23 is provided between the stator 21 and the base section 3b in a state of contact and sealing between them. This increases the temperature on the outer periphery of the flow path from the outlet of the final stage thread groove pump section 10b to the exhaust port 9, suppressing the generation of deposits due to exhaust gas.

[0022] Furthermore, in this embodiment, a shielding portion 24 is connected to the stator 21. The shielding portion 24 is a substantially annular member and has a cross-sectional shape, for example, as shown in Fig. 1. The shielding portion 24 is provided to suppress contact of the exhaust gas with the shaft portion 13 in the exhaust gas flow path 31 from the final stage thread groove pump portion 10b to the exhaust port 9.

[0023] FIG. 2 is a diagram for explaining the details of the shape of the shielding portion 24 in FIG.

[0024] For example, as shown in FIG. 2, the shielding part 24 has a surface 24a1 at its end 24a facing the rotor 11, and the surface 24a1 and the rotor 11 form a gas inflow suppression structure. In this embodiment, the gas inflow suppression structure is formed by making the gap between the end 24a of the shielding part 24 (the surface 24a1 facing the rotor 11 described above) and the rotor 11 (the bottom surface 11a facing the end 24a) very small. The width of the gap (i.e., the distance between the surface 24a1 and the rotor 11) is, for example, about 1 to 1.5 mm. The width of the gap may be approximately the same as or less than the distance from the wall surface 13b of the shaft part 13 to the inner peripheral surface of the shielding part 24. The gas inflow suppression structure may be, for example, a non-contact seal structure.

[0025] In this embodiment, the shielding portion 24 includes an intermediate portion 24b that extends (here, vertically upward) along the wall surface 13b of the shaft portion 13 to the end portion 24a, and is formed so that the thickness TB of the intermediate portion 24b is smaller than the thickness TA of the end portion 24a. This suppresses the conduction of heat from the stator 21 to the rotor 11 through the shielding portion 24, and increases the flow path area of ​​the flow path 31.

[0026] Furthermore, the shielding portion 24 is configured 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 24a of the shielding portion 24 is approximately 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). This prevents the flow path near the outlet of the thread groove pump portion 10b from being blocked by the end 24a of the shielding portion 24.

[0027] Here, the distance between the shaft portion 13 and the shielding portion 24 and the distance between the shaft portion 13 and the rotor 11 may be approximately the same. Also, the distance between the shaft portion 13 and the shielding portion 24 and the distance between the end portion 24a of the shielding portion 24 and the rotor 11 may be approximately the same. This strengthens the above-mentioned gas inflow suppression structure.

[0028] Here, the stator 21 is a heating member equipped with a heater 22, is made of, for example, aluminum, and faces the flow path 31. In the first embodiment, the shielding portion 24 is made into one member, and is fixed, for example, by screws, so as to be directly joined to the stator 21 as the heating member (without an insulating material in between). The shielding portion 24 may be realized by molding a part of the stator 21 as the heating member (that is, in this case, the shielding portion 24 becomes a part of the heating member). In this way, heat is transferred 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.

[0029] The temperature of the stator 21 and other components is controlled by using a temperature sensor 25 provided in the stator 21.

[0030] For example, the width of the gap between the end 24a 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.

[0031] Next, the operation of the vacuum pump according to the first embodiment will be described.

[0032] A chamber or the like is connected to the intake port 7 of the vacuum pump, and the motor section 6 operates according to commands from a control device (not shown), causing the rotor shaft 4 to rotate, which in turn causes the rotor 11 to rotate. As a result, in the turbo molecular pump section 10a, the rotor blades 3a and stator blades 2 cause the gas molecules that have flown in through the intake port 7 to proceed into the flow path, and in the subsequent thread groove pump section 10b, the rotor 11 and stator 21 exhaust the gas molecules into the flow path 31 as exhaust gas, pass through the flow path 31, and are exhausted from the exhaust port 9.

[0033] Furthermore, the shielding portion 24 is supplied with heat from the stator 21 as a heating member, and thereby becomes hotter than the shaft portion 13, thereby suppressing the generation of deposits on the shielding portion 24. For example, the stator 21 is temperature-controlled to be higher than about 100 degrees Celsius, and the base portion 13a is temperature-controlled to be lower than about 60 degrees Celsius.

[0034] As described above, according to the first embodiment, the thread groove pump section 10b includes the shaft section 13, the rotor 11 arranged on the outer periphery of the shaft section 13, and the stator 21 arranged on the outer periphery of the rotor 11. The shielding section 24 suppresses contact of the exhaust gas with the shaft section 13 in the exhaust gas flow path from the pump section 10b to the exhaust port 9. The end section 24a of the shielding section 24 has a surface 24a1 facing the rotor 11.

[0035] As a result, the shielding portion 24 restricts the progress of the exhaust gas, making it less likely for the exhaust gas to come into contact with the relatively cool wall surface of the shaft portion 13 and the upper surface of the base portion 13b, thereby suppressing the generation of deposits caused by the exhaust gas.

[0036] Embodiment 2

[0037] FIG. 3 is a diagram illustrating details of a shielding portion in a vacuum pump according to a second embodiment of the present invention.

[0038] In the vacuum pump shown in FIG. 3, as in the first embodiment, a rotor 52 is provided on the outer periphery of a shaft portion 51, and a stator 53 of a thread groove pump portion is provided on the outer periphery of the rotor 52. Furthermore, a spacer 54 is provided to be joined to the stator 53, and a heater 55 is provided on the spacer 54. The shaft portion 51 is joined to a head portion 56, and as in the first embodiment, the shaft portion 51 is cooled by cooling the head portion 56. A heat insulating member 57 is provided between the spacer 54 as a heating member and the head portion 56. Here, the spacer 54 is provided as a member separate from the stator 53, and therefore the spacer 54 may be made of, for example, stainless steel in order to ensure strength at high temperatures.

[0039] In the second embodiment, the shielding portion 58 is fixed to the spacer 54 as shown in Fig. 3. The shielding portion 58 also has a substantially annular shape.

[0040] In the second embodiment, the shielding portion 58 is configured so that its end has a gas inflow suppression structure between it and the rotor 52. In this embodiment, the gas inflow suppression structure is formed by making the gap between the end of the shielding portion 58 and the rotor 52 very small.

[0041] Additionally, the shielding portion 58 has an intermediate portion that extends along the wall surface of the shaft portion 51 to the end portion of the shielding portion 58, and is formed so that the thickness of the intermediate portion is smaller than the thickness of the end portion.

[0042] Furthermore, shielding portion 58 is configured and positioned so that the distance from the wall surface of shaft portion 51 to the outer peripheral surface of the end of shielding portion 58 is approximately the same as or shorter than the distance from the wall surface of shaft portion 51 to the outer peripheral surface of rotor 52 (the part in the thread groove pump portion).

[0043] Other configurations and operations of the vacuum pump according to the second embodiment are similar to those of the first embodiment, so the description thereof will be omitted.

[0044] Embodiment 3

[0045] FIG. 4 is a top view showing an example of a groove structure 24a2 provided on a surface 24a1 of a shielding portion 24 in a vacuum pump according to the third embodiment.

[0046] The groove structure 24a2 shown in Fig. 4 has a shape that suppresses the inflow of exhaust gas to the shaft portion 13, 51 side through a gap between the shielding portion 24 (surface 24a1) and the rotor 11, 52 (bottom surface 11a). The groove structure 24a2 has a plurality of grooves inclined with respect to the radial direction, and the wall surfaces (flat or curved surfaces) of the plurality of grooves are inclined at an angle and in a direction according to the rotation direction of the rotor 11, 52 so that exhaust gas (gas molecules, etc.) that has entered the grooves is discharged to the outside of the rotor 11, 52 by the relative rotation of the shielding portion 24 and the rotor 11, 52.

[0047] The cross-sectional shape of each groove in the groove structure 24a2 is not particularly limited and may be, for example, substantially rectangular or substantially triangular.

[0048] Furthermore, the shape of each groove in the groove structure 24a2 may be linear or spiral.

[0049] Other configurations and operations of the vacuum pump according to embodiment 3 are similar to those of embodiment 1 or 2, so description thereof will be omitted.

[0050] It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. In other words, such changes and modifications are intended to be included within the scope of the claims.

[0051] For example, in the above-mentioned third embodiment, the groove structure 24a2 is provided on the surface 24a1 of the shielding portion 24, but a similar 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. Moreover, the groove structure 24a2 may not be provided on the entire surface 24a1 of the shielding portion 24, but may be provided only on, for example, a part of the outer circumferential side.

[0052] Also, for example, in the above-mentioned third embodiment, purge gas may be introduced from the purge gas port 26 and passed through 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 efficiently discharged to the exhaust gas flow path through the gap due to the drag effect of the groove structure 24a2 or the like, so that the exhaust gas is less likely to come into contact with the wall surface of the shaft portion 13 or the upper surface of the base portion 13b.

[0053] For example, in the first and second embodiments, the gas inflow suppression structure may be, for example, a labyrinth seal structure. [Industrial Applicability]

[0054] The present invention is applicable to, for example, a vacuum pump. [Explanation of symbols]

[0055] 9. Exhaust port 10b Thread groove pump section (an example of a pump section) 11,52 Rotor 13,51 Shaft 21,53 Stator (an example of a stator and a heating member) 24,58 Shielding part 24a end 24a1 side 24a2 groove structure 24b Middle part 31 Flow Path 54 Spacer (an example of a heating element)

Claims

1. A pump section including a head section, a heat insulating member, a shaft section extending from the head section, a rotor disposed on an outer periphery of the shaft section, and a stator disposed on an outer periphery of the rotor; an exhaust gas flow path from the pump portion to an exhaust port; a shielding portion that suppresses contact of the exhaust gas with the shaft portion in the flow passage; A heating member having a heater, The shaft portion is cooled. an end portion of the shielding portion has a surface facing a lower end surface of the rotor in the axial direction, the shielding portion is spaced from the shaft portion and is a member fixed to the heating member or a part of the heating member; the heat insulating member (a) is disposed between the heating member and the shielding portion and the head portion, and (b) has a first end surface facing the head portion and a second end surface facing the heating member, the first end surface includes a contact portion that is in contact with the head portion and a non-contact portion that is not in contact with the head portion, the second end surface includes a contact portion in contact with the heating member and a non-contact portion not in contact with the heating member; A vacuum pump characterized by:

2. The shielding portion includes an intermediate portion extending along a wall surface of the shaft portion to the end portion, The thickness of the intermediate portion is smaller than the thickness of the end portion; 2. The vacuum pump according to claim 1,

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

4. 4. The vacuum pump according to claim 1, further comprising a groove structure on at least one of the surface of the shielding portion and the surface of the rotor facing the surface, the groove structure suppressing an inflow of the exhaust gas to the shaft portion side through a gap between the shielding portion and the rotor.

5. 5. The vacuum pump according to claim 1, wherein the heating member is the stator.

Images