Patent Application
20240410395
This application claims priority under 35 U.S.C § 119 to Japanese Patent Application No. 2023-095518 filed on Jun. 9, 2023. The entire disclosure of Japanese Patent Application No. 2023-095518 is hereby incorporated herein by reference.
The present invention relates to a vacuum pump.
In the field of, e.g., a semiconductor manufacturing device, a turbo-molecular pump which is one type of vacuum pump is used for generating high vacuum atmosphere. In the turbo-molecular pump, a rotor rotates at high speed in a case, and for this reason, for the purpose of reducing transmission of energy upon breakdown of the rotor to a device side to which the turbo-molecular pump is connected, there has been disclosed a structure for absorbing such energy by deformation of a flange portion (see, for example, JP-A-2023-003070).
In some cases, in order to ensure strength against impact upon breakdown of a rotor of a vacuum pump, not only the upper side on which a flange is provided as in the above-described patent literature but also the bottom side are fixed. As a bottom-side fixing structure, for example, a vacuum pump main body is fastened to a bottom fixing plate with a pump fixing bolt, and the bottom fixing plate is fastened to a fixing target with a bottom fixing bolt.
However, strength withstanding impact of breakdown torque needs to be ensured for the bottom fixing bolt, and for this reason, the number of bolts, the strength of the bolt, and a bolt pitch circle diameter need to be ensured. This leads to an increase in the size of the bottom-side fixing structure.
An object of the present invention is to provide a vacuum pump configured so that a bottom-side fixing structure can be reduced in size.
A vacuum pump according to a first aspect of the present invention includes a vacuum pump main body and a bottom fixing member. The vacuum pump main body has a bottom surface and a side surface. The side surface has a first flat surface formed so as to extend from the bottom surface. The bottom fixing member is fastened to the bottom surface of the vacuum pump main body. The bottom fixing member has a second flat surface facing the first flat surface.
A vacuum pump according to a second aspect of the present invention includes a bottom surface and a side surface. The bottom surface is fastened to a fixing target. The side surface has a first flat surface formed so as to extend from the bottom surface. The first flat surface faces a second flat surface formed at the fixing target in a state in which the bottom surface is fastened to the fixing target.
According to the above-described aspects of the present invention, the vacuum pump can be provided, which is configured so that the bottom-side fixing structure of the vacuum pump can be reduced in size.
Hereinafter, a vacuum pump system according to an embodiment of the invention will be described with reference to the drawings.
The vacuum pump main body 100 includes a turbine portion P1 and a drag pump portion P2. The turbine portion P1 forms a turbo-molecular pump. The drag pump portion P2 forms a screw groove pump. The vacuum pump main body 100 is connected to the chamber. Gas from the chamber is discharged by the turbine portion P1, and thereafter, is discharged by the drag pump portion P2. Then, the gas is discharged to the outside of the vacuum pump main body 100.
As shown in
The housing 2 has a case 8, a base 9, and a fixed flange 10. The housing 2 is made of metal such as aluminum alloy or iron. The case 8 is a tubular member having the fixed flange 10 at one end.
The case 8 houses the plurality of stator blade units 5 and plural stages of rotor blade units 22 provided in the rotor 3. The case 8 has a first end portion 11, a second end portion 12, and a side surface 13.
The first end portion 11 is attached to a pumping target device. A suction port 14 is provided in the first end portion 11. The second end portion 12 is positioned opposite to the fixed flange 10 in the direction of the center axis A of the rotor 3. The second end portion 12 is connected to the base 9. The side surface 13 is provided between the first end portion 11 and the second end portion 12. A first internal space S1 is formed inside the case 8.
The base 9 is arranged so as to close an opening of the case 8 on the second end portion 12 side. The base 9 houses the stator cylindrical portion 6 and a rotor cylindrical portion 23 provided in the rotor 3. The base 9 is connected to the second end portion 12 of the case 8 at a base end portion 33. A second internal space S2 is formed inside the base 9. The second internal space S2 communicates with the first internal space S1. An exhaust port 30 is formed in a side surface 32 of the base 9. A connector 16 to be connected to an exhaust pipe is arranged in the exhaust port 30. The exhaust port 30 communicates with the second internal space S2. The configuration of the base 9 will be further described later.
The fixed flange 10 is connected to the case 8. The fixed flange 10 protrudes from the case 8. The fixed flange 10 is fixed to the pumping target device with a bolt. Note that “connect” includes joining of separate members. Further, “connect” includes continuous formation of separate portions in an integrated member.
The rotor 3 has a shaft 21, the plural stages of rotor blade units 22, and the rotor cylindrical portion 23. The shaft 21 extends along the axis A of the rotor 3. In description below, in the direction along the axis A, a direction from the case 8 to the base 9 will be defined as below, and the opposite direction thereof will be defined as above.
The vacuum pump main body 100 includes a protection bearing 29 and a plurality of bearings 24A to 24C. The protection bearing 29 functions as a touchdown bearing configured to limit radial runout of the upper side of the shaft 21. The protection bearing 29 is attached to the base 9. In a state in which the shaft 21 is in steady rotation, the shaft 21 does not contact the protection bearing 29. When great disturbance is applied or whirling of the shaft 21 becomes greater upon acceleration or deceleration of rotation, the shaft 21 contacts the inner surface of an inner ring of the protection bearing 29. For example, a ball bearing can be used as the protection bearing 29.
The plurality of bearings 24A to 24C rotatably supports the rotor 3. The plurality of bearings 24A to 24C is attached to the base 9. The plurality of bearings 24A to 24C includes, for example, a magnetic bearing. Note that the plurality of bearings 24A to 24C may include other types of bearings such as a ball bearing.
Each of the plural stages of rotor blade units 22 is connected to the shaft 21. The plural stages of rotor blade units 22 are arranged at intervals in the direction along the axis A. Each rotor blade unit 22 includes a plurality of rotor blades 25. Although not shown in the figure, each of the plurality of rotor blades 25 radially extends about the shaft 21. Note that in the drawing, reference numerals are assigned only to one of the plural stages of rotor blade units 22 and one of the plurality of rotor blades 25 and no reference numerals are assigned to the other rotor blade units 22 and the other rotor blades 25.
The rotor cylindrical portion 23 is connected to the shaft 21. The rotor cylindrical portion 23 is arranged below the rotor blade units 22. The rotor cylindrical portion 23 is in a cylindrical shape, and extends in the direction along the axis A. The rotor cylindrical portion 23 is arranged so as to surround the shaft 21 on the outer peripheral side of the shaft 21.
The motor 4 rotationally drives the rotor 3. For example, a DC brushless motor is used as the motor 4. The motor 4 has a motor rotor and a motor stator. For example, the motor rotor is attached to the shaft 21. The motor stator is attached to the base 9. The motor stator is arranged so as to face the motor rotor.
The plural stages of stator blade units 5 are connected to the inner surface of the case 8. The plural stages of stator blade units 5 are arranged at intervals in the direction along the axis A. Each of the plural stages of stator blade units 5 is arranged between adjacent ones of the plural stages of rotor blade units 22. Each stator blade unit 5 includes a plurality of stator blades 28. Although not shown in the figure, each of the plurality of stator blades 28 radially extends about the shaft 21.
The plural stages of rotor blade units 22 and the plural stages of stator blade units 5 form the turbine portion P1 (turbo-molecular pump). Note that in the drawing, reference numerals are assigned only to one of the plurality of stator blade units 5 and one of the plurality of stator blades 28 and no reference numerals are assigned to the other stator blade units 5 and the stator blades 28.
The stator cylindrical portion 6 is arranged on the outside of the rotor cylindrical portion 23 in the radial direction. The stator cylindrical portion 6 is connected to the base 9. The stator cylindrical portion 6 is arranged so as to face the rotor cylindrical portion 23 in the radial direction of the rotor cylindrical portion 23.
A spiral screw groove is provided in the inner peripheral surface of the stator cylindrical portion 6. The rotor cylindrical portion 23 and the stator cylindrical portion 6 form the drag pump portion P2 (screw groove pump). Note that the spiral screw groove is not necessarily provided in the inner peripheral surface of the stator cylindrical portion 6, but may be provided in the outer peripheral surface of the rotor cylindrical portion 23.
The base 9 is in a substantially cylindrical shape having a bottom. As shown in
The side surface 32 is arranged so as to extend toward the suction port 14 from the periphery of the bottom surface 31. The base end portion 33 is arranged at the end of the side surface 32 on the suction port 14 side. The base end portion 33 protrudes outward (direction apart from the axis A) from the side surface 32. As shown in
The outer shape of the side surface 32 is such a shape that columns having substantially different outer diameters are arranged one above the other. The side surface 32 is formed such that the outer diameter thereof is greater on the bottom surface 31 side than on the suction port 14 side. The side surface 32 has a pump-side flat surface 34 (first flat surface). The outer shape of the side surface 32 is not limited to above, and may be a cylindrical shape with the same diameter.
As shown in
As shown in
As shown in
The bottom fixing plate 120 has a main body portion 40 and a plurality of protruding portions 41. The main body portion 40 is in a plate shape. The main body portion 40 has a first surface 51, a second surface 52, an opening 53, and the recessed portion 54. The first surface 51 is a surface on a side on which the vacuum pump main body 100 is to be mounted. The second surface 52 is a surface on a side on which the fixing target 200 is to be arranged.
The opening 53 penetrates the main body portion 40 from the first surface 51 to the second surface 52. The opening 53 is provided for inserting, e.g., a cable extending from the power source unit 210 to the vacuum pump main body 100.
The recessed portion 54 is formed in the first surface 51. The bottom surface 31 and side lower end portion 35 of the vacuum pump main body 100 are fitted in the recessed portion 54. The recessed portion 54 is formed with the opening 53. The recessed portion 54 has a mount surface 55 and an inner peripheral surface 56. The bottom surface 31 of the vacuum pump main body 100 is mounted on the mount surface 55. The inner peripheral surface 56 is formed upward from the peripheral edge of the mount surface 55. The inner peripheral surface 56 faces the side lower end portion 35 of the vacuum pump main body 100.
The inner peripheral surface 56 includes the fixing-side flat surface 56a and a curved surface 56b. The fixing-side flat surface 56a faces the flat portion 35a when the vacuum pump main body 100 is mounted in the recessed portion 54. Since the flat portion 35a is included in the pump-side flat surface 34, it can be said that the fixing-side flat surface 56a faces the pump-side flat surface 34. As shown in
A plurality of through-holes 40a penetrating the main body portion 40 from the second surface 52 to the mount surface 55 is formed in the main body portion 40. The through-holes 40a are arranged on a circumference about the axis A. In the present embodiment, eight through-holes 40a are formed, but a reference numeral is assigned only to one of the through-holes 40a in the figure. For example, the inner peripheral surface of the through-hole 40a is a smooth curved surface, and is formed with no internal thread shape. The pump fixing bolt 130 (see
A plurality of through-holes 40b penetrating the main body portion 40 from a portion of the first surface 51 outside the recessed portion 54 to the second surface 52 is provided in the main body portion 40. The plurality of through-holes 40b is arranged on a circumference about the axis A. In the present embodiment, eight through-holes 40b are formed, but a reference numeral is assigned only to one of the through-holes 40b in the figure. For example, the inner peripheral surface of the through-hole 40b is a smooth curved surface, and is formed with no internal thread shape. The through-holes 40b are arranged along the periphery of the main body portion 40. A bolt 160 shown in
The plurality of protruding portions 41 protrudes outward from the outer periphery of the main body portion 40. In the present embodiment, two protruding portions 41 are provided. Each protruding portion 41 is in a plate shape. In each protruding portion 41, a plurality of through-holes 41a into which the bottom fixing bolts 150 are to be inserted is formed. In the present embodiment, six through-holes 41a are formed in one protruding portion 41, but a reference numeral is assigned only to one of the through-holes 41a in the figure. The bottom fixing tool 140 is arranged between the through-holes 41a and the fixing target 200. The bottom fixing tool 140 is in a cylindrical shape. For example, the inner peripheral surface of the through-hole 41a and the inner periphery of the bottom fixing tool 140 are smooth curved surfaces, and are formed with no internal thread shape. The bottom fixing bolt 150 is inserted into the fixing target 200 from above through the through-hole 41a of the protruding portion 41 and the inside of the bottom fixing tool 140. The bottom fixing bolt 150 is arranged in parallel with the axis A. An external thread of the outer periphery of the bottom fixing bolt 150 is screwed with an internal thread of the inner periphery of a bolt hole of the fixing target 200. With this configuration, the bottom fixing plate 120 can be fixed to the fixing target 200.
In the vacuum pump 1 of the present embodiment, the pump-side flat surface 34 of the vacuum pump main body 100 and the fixing-side flat surface 56a of the bottom fixing plate 120 are provided as flat surfaces facing each other. Thus, the pump-side flat surface 34 contacts the fixing-side flat surface 56a upon breakdown of the rotor, and therefore, the bottom fixing plate 120 can receive breakdown torque by the surface and breakdown torque on the bottom fixing bolt 150 can be reduced.
There is a clearance between the inner peripheral surface 56 of the bottom fixing plate 120 and the side lower end portion 35.
Assuming that the width of the pump-side flat surface 34 in plan view is W1 and the width of the fixing-side flat surface 56a is W2, W2 is preferably greater than W1. The widths W1, W2 and the clearance d are preferably set such that the pump-side flat surface 34 contacts the fixing-side flat surface 56a when the vacuum pump main body 100 rotates about the axis A relative to the bottom fixing plate 120.
One embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment and various changes can be made without departing from the gist of the invention.
In the above-described embodiment, only one pair of the pump-side flat surface 34 and the fixing-side flat surface 56a is provided, but plural pairs may be provided.
In the above-described embodiment, the pump-side flat surface 34 extends to the position higher than the fixing-side flat surface 56a, but may be formed to a portion (flat portion 35a) at the same height as that of the fixing-side flat surface 56a.
In the above-described embodiment, the recessed portion 54 is formed in the bottom fixing plate 120, and the fixing-side flat surface 56a facing the pump-side flat surface 34 is provided at the inner peripheral surface 56 of the recessed portion 54. However, the present invention is not limited to this configuration.
In the above-described embodiment, the two protruding portions 41 are provided, and the six through-holes 41a are formed in each protruding portion 41. However, the present invention is not limited to these numbers. Similarly, the numbers of through-holes 40a, 40b are not limited to eight as described above.
In the above-described embodiment, the power source unit 210 is arranged on the lower side of the bottom fixing plate 120, and the bottom fixing plate 120 and the power source unit 210 are fastened to each other with the bolts. However, the power source unit 210 is not necessarily arranged on the lower side of the bottom fixing plate 120.
In the above-described embodiment, the vacuum pump main body 100 is fixed to the fixing target 200 through the bottom fixing plate 120, but as shown in
In the above-described embodiment, there is the clearance between the inner peripheral surface 56 of the bottom fixing plate 120 and the side lower end portion 35, but the side lower end portion 35 of the vacuum pump main body 100 and the inner peripheral surface 56 of the bottom fixing plate 120 may contact each other with no clearance formed partially or entirely therebetween. Alternatively, the pump-side flat surface 34 and the fixing-side flat surface 56a may contact each other with no clearance therebetween.
Those skilled in the art understand that the above-described plurality of exemplary embodiments are specific examples of the following aspects.
According to the vacuum pump of the first item, when a rotor of the vacuum pump main body is broken down, the first flat surface of the vacuum pump main body contacts the second flat surface of the bottom fixing member. With this configuration, the bottom fixing member can receive, by the surface, breakdown torque generated on the vacuum pump main body, and breakdown torque on a second fastening member used for fixing the bottom fixing member and a fixing target to each other can be reduced. Thus, the number of second fastening members can be decreased, the strength can be lowered, and a bolt pitch circle diameter (diameter of a circle having, as a radius, a length from the center axis of the rotor to a bolt) can be decreased. As a result, a bottom-side fixing structure of the vacuum pump can be reduced in size.
According to the vacuum pump of the second item, when the rotor is broken down, the first flat surface of the vacuum pump main body contacts the second flat surface formed at the inner peripheral surface of the recessed portion, and therefore, the bottom fixing member can receive the breakdown torque by the surface.
According to the vacuum pump of the third item, when the rotor is broken down, breakdown torque on the first fastening member for fastening the vacuum pump main body and the bottom fixing member to each other can be reduced.
According to the vacuum pump of the fourth item, when the rotor is broken down, breakdown torque on the second fastening member for fastening the bottom fixing member and the fixing target to each other can be reduced.
According to the vacuum pump of the fifth item, when the rotor is broken down, the first flat surface contacts the second flat surface before the second fastening member contacts the inner peripheral surface of the through-hole, and therefore, breakdown torque on the fastening member can be reduced.
According to the vacuum pump of the sixth item, when a rotor of a vacuum pump main body is broken down, the first flat surface of the vacuum pump main body contacts the second flat surface of the bottom fixing member. With this configuration, the bottom fixing member can receive, by the surface, breakdown torque generated on the vacuum pump main body, and breakdown torque on a fastening member for fastening the bottom fixing member and the vacuum pump main body to each other or breakdown torque on a fastening member used for fixing the bottom fixing member and the fixing target to each other can be reduced. Thus, the numbers of first fastening members and second fastening members can be decreased, the strength can be lowered, and a bolt pitch circle diameter (diameter of a circle having, as a radius, a length from the center axis of the rotor to a bolt) can be decreased. As a result, a bottom-side fixing structure of the vacuum pump can be reduced in size.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-095518 | Jun 2023 | JP | national |
