Shut-off valves and vacuum pumps

Abstract

Miniaturize the shut-off valve. [Solution] The shut-off valve 50 includes a valve seat 53 positioned between a first opening O1 and a second opening O2, and a valve body 54 positioned on the second opening O2 side of the valve seat 53, which moves in a first direction D1 from the second opening O2 to the first opening O1 due to the pressure of the gas flowing from the second opening O2 to the first opening O1. The valve body 54 has a valve body shaft 54a extending in the first direction D1, and a contact surface 54b that contacts the valve seat 53 when the valve body 54 moves in the first direction D1. The contact surface 54b is positioned on the second opening O2 side of the first end e1 of the valve body shaft 54a on the first direction D1 side.

Description

Technical Field

[0001] The present invention relates to a shut-off valve and a vacuum pump.

Background Art

[0002] In the field of semiconductor manufacturing equipment and the like, a turbo molecular pump, which is a type of vacuum pump, is used to create a high-vacuum atmosphere (see, for example, Patent Document 1). In a turbo molecular pump, a rotor is disposed inside a housing, and a turbo molecular pump section is formed above the rotor. Moving blades are arranged on the rotor side, and stationary blades are arranged on the housing side. The moving blades and the stationary blades are arranged in a plurality of stages alternately while maintaining a gap of several millimeters. Further, a drag pump section is formed below the rotor. When exhausting, the rotor rotates at a rotational speed of tens of thousands of revolutions per minute in a magnetically levitated state. The gas to be exhausted flies from the exhaust target space to the intake port of the vacuum pump, and is compressed by the turbo molecular pump section and the drag pump section and discharged to the exhaust port side.

[0003] When air is suddenly introduced due to a trouble during the operation of such a turbo molecular pump (when air rushes in), the magnetically levitated rotor contacts the bearing and decelerates rapidly. As a result, the bearing wears out, and when air intrusion is repeated, the bearing may fail and the rotor may be damaged accordingly.

[0004] For this reason, in Patent Document 1, a shut-off valve for preventing the inflow of air into the vacuum pump when air rushes in has been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Currently, miniaturization of shut-off valves is being considered. However, miniaturizing conventional shut-off valves is difficult. Specifically, the valve body of a shut-off valve has a contact surface that abuts against the valve seat of the shut-off valve, and a shaft on which the contact surface is provided. In conventional shut-off valves, the contact surface was located at the end of the valve body's shaft. For this reason, it has been difficult to miniaturize conventional shut-off valves.

[0007] The objective of this invention is to miniaturize the shut-off valve. [Means for solving the problem]

[0008] A shut-off valve according to one aspect of the present invention comprises a valve seat and a valve body. The valve seat is positioned between a first opening and a second opening. The valve body is positioned on the second opening side of the valve seat and moves in a first direction from the second opening to the first opening due to the pressure of the gas flowing from the second opening to the first opening. In this shut-off valve, the valve body has a valve body shaft extending in the first direction and a contact surface that contacts the valve seat when the valve body moves in the first direction. The contact surface is positioned on the second opening side of the first end of the valve body shaft on the first direction side. [Effects of the Invention]

[0009] According to the above-described aspect of the present invention, the contact surface of the valve body that contacts the valve seat of the shut-off valve is positioned on the second opening side of the valve body shaft than the first end on the first direction side. As a result, compared to conventional shut-off valves in which the contact surface is positioned at the end on the first direction side of the shaft, the distance between the end on the opposite side of the first direction side of the valve body shaft and the contact surface can be shortened, thus allowing the size of the housing that houses the valve body to be smaller than in conventional valves.

[0010] Furthermore, by positioning the contact surface of the valve body on the second opening side of the valve body shaft beyond the first end, the center of gravity of the valve body can be positioned closer to the center of the valve body than to the first end. This prevents the first end of the valve body from lowering vertically and creating resistance to the movement of the valve body in the first direction when the shut-off valve is positioned so that the first direction of movement of the valve body is horizontal (perpendicular to the vertical direction) or close to it. In other words, by positioning the contact surface of the valve body on the second opening side of the valve body shaft beyond the first end, the valve body can move smoothly in the first direction. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram showing the configuration of a vacuum pump. [Figure 2] This is a cross-sectional view of a shut-off valve. [Figure 3] This is a perspective view of the shut-off valve from the second opening side. [Figure 4] This diagram shows a shut-off valve in a state where the first opening and the second opening are spatially separated. [Figure 5] This is a diagram showing a modified example of a shut-off valve body. [Modes for carrying out the invention]

[0012] The vacuum pump will be described below using Figure 1. Figure 1 shows the configuration of the vacuum pump 1. The vacuum pump 1 has a housing 2, a rotor 3, a motor 4, a plurality of stator blade units 5, and a stator cylindrical section 6.

[0013] The housing 2 houses the rotor 3, the motor 4, a plurality of stator blade units 5, and the stator cylindrical section 6. The housing 2 has a casing 8, a base 9, and a fixing flange 10. The housing 2 is made of a metal such as aluminum alloy or iron. The casing 8 is a cylindrical member having a fixing flange 10 at one end.

[0014] The casing 8 houses a plurality of stator blade units 5 and a plurality of rotor blade units 22 provided on the rotor 3. The casing 8 has a first end portion 11, a second end portion 12, and a side portion 13.

[0015] The first end 11 is attached to the exhaust device. The first end 11 is provided with an intake port 14. The second end 12 is located on the opposite side of the fixed flange 10 in the axial direction G1 of the rotor 3. The second end 12 is connected to the base 9. The side portion 13 connects the first end 11 and the second end 12. A first internal space S1 is formed inside the casing 8.

[0016] The base 9 is positioned to close the opening on the second end 12 side of the casing 8. The base 9 houses the stator cylindrical portion 6 and the rotor cylindrical portion 23 provided on the rotor 3. The base 9 has a base end 15 and an exhaust port 16. The base end 15 is connected to the second end 12 of the casing 8. A second internal space S2 is formed inside the base 9. The second internal space S2 is in communication with the first internal space S1. The exhaust port 16 is in communication with the second internal space S2.

[0017] The fixed flange 10 is connected to the casing 8. The fixed flange 10 protrudes from the casing 8. The fixed flange 10 is fixed to the exhaust device by bolts 20. Note that "connection" includes the joining of separate components. Furthermore, "connection" also includes the joining of separate parts within a single component.

[0018] The rotor 3 comprises a shaft 21, a multi-stage rotor blade unit 22, and a rotor cylindrical section 23. The shaft 21 extends in the axial direction G1 of the rotor 3. In the following description, in the axial direction G1, the direction from the casing 8 toward the base 9 is defined as downward, and the opposite direction is defined as upward.

[0019] The vacuum pump 1 includes a protective bearing 29 and a plurality of bearings 24A to 24C. The protective bearing 29 functions as a touch-down bearing that limits the radial runout of the upper side of the shaft 21. The protective bearing 29 is attached to the base 9. In the state where the shaft 21 is rotating steadily, the shaft 21 and the protective bearing 29 are not in contact. When a large disturbance is applied or when the runout of the shaft 21 becomes large during acceleration or deceleration of rotation, the shaft 21 contacts the inner surface of the inner ring of the protective bearing 29. The protective bearing 29 can use, for example, a ball bearing or the like.

[0020] The plurality of bearings 24A to 24C rotatably support the rotor 3. The plurality of bearings 24A to 24C are attached to the base 9. The plurality of bearings 24A to 24C include, for example, magnetic bearings. However, the plurality of bearings 24A to 24C may include other types of bearings such as ball bearings.

[0021] The plurality of stages of rotor blade units 22 are each connected to the shaft 21. The plurality of stages of rotor blade units 22 are arranged at intervals in the axial direction G1. Each rotor blade unit 22 includes a plurality of rotor blades 25. Each of the plurality of rotor blades 25 extends radially around the shaft 21. In the drawing, only one of the plurality of stages of rotor blade units 22 and one of the plurality of rotor blades 25 are labeled, and the labels of the other rotor blade units 22 and the other rotor blades 25 are omitted.

[0022] The rotor cylindrical portion 23 is connected to the shaft 21. The rotor cylindrical portion 23 is arranged below the rotor blade unit 22. The rotor cylindrical portion 23 is cylindrical and extends in the axial direction G1. The rotor cylindrical portion 23 is arranged to surround the shaft 21 on the outer peripheral side of the shaft 2x.

[0023] Motor 4 rotates the rotor 3. For example, a DC brushless motor is used as motor 4. Motor 4 has a motor rotor 26 and a motor stator 27. The motor rotor 26 is attached to the shaft 21. The motor stator 27 is attached to the base 9. The motor stator 27 is positioned opposite the motor rotor 26.

[0024] The multi-stage stator blade unit 5 is connected to the inner surface of the casing 8. The multi-stage stator blade unit 5 is spaced apart from each other in the axial direction G1. Each of the multi-stage stator blade unit 5 is positioned between the multi-stage rotor blade units 22. Each stator blade unit 5 includes multiple stator blades 28. Each of the multiple stator blades 28 extends radially from the shaft 21.

[0025] The multi-stage rotor blade unit 22 and the multi-stage stator blade unit 5 constitute the turbine section P1 (turbomolecular pump). In the drawing, only one of the multiple stator blade units 5 and one of the multiple stator blades 28 are labeled with a reference numeral, while the reference numerals for the other stator blade units 5 and other stator blades 28 are omitted.

[0026] The stator cylindrical portion 6 is positioned radially outward from the rotor cylindrical portion 23. The stator cylindrical portion 6 is connected to the base 9. The stator cylindrical portion 6 is positioned facing the rotor cylindrical portion 23 in the radial direction of the rotor cylindrical portion 23.

[0027] The inner circumferential surface of the stator cylindrical portion 6 is provided with helical screw grooves. The rotor cylindrical portion 23 and the stator cylindrical portion 6 constitute the drag pump portion P2 (screw groove pump). Note that the helical screw grooves may be provided on the outer circumferential surface of the rotor cylindrical portion 23 instead of the inner circumferential surface of the stator cylindrical portion 6.

[0028] The vacuum pump 1 described above evacuates the gas inside the device to be evacuated, which is connected to the first end 11 of the casing 8, using the turbine section P1, then the drag pump section P2, and finally exhausts the gas to the outside through the exhaust port 16, thereby creating a vacuum inside the device to be evacuated.

[0029] If a problem occurs in the vacuum pump 1 during operation, air may enter the internal space from outside the exhaust port 16 of the vacuum pump 1. Such air intrusion can cause contact between the rotor 3, which is magnetically levitating, and its bearings. When the rotor 3 comes into contact with the bearings, the bearings wear out. If air intrusion from outside the vacuum pump 1 into the internal space occurs repeatedly, the bearings will fail. If the bearings fail, the rotor 3 may be damaged. To prevent this, a shut-off valve 50 is provided at the exhaust port 16 to prevent air from flowing into the internal space of the vacuum pump 1 from the outside.

[0030] The shut-off valve 50 will be described in detail below with reference to Figures 2 and 3. Figure 2 is a cross-sectional view of the shut-off valve 50. Figure 3 is a perspective view of the shut-off valve 50 from the second opening O2 side. The shut-off valve 50 includes a first housing 51, a second housing 52, a valve seat 53, and a valve body 54.

[0031] The first housing 51 is a hollow member. The internal space of the hollow first housing 51 is the first opening O1. The first housing 51 has a first housing end 51a and a second housing end 51b. The first housing end 51a is flange-shaped and is connected to the exhaust port 16 of the vacuum pump 1. That is, the first opening O1 is connected to the exhaust port 16. The second housing 52 is fixed to the second housing end 51b.

[0032] The second housing 52 is a hollow member. The second housing 52 has a third housing end 52a and a fourth housing end 52b. The third housing end 52a is fixed to the second housing end 51b of the first housing 51. The third housing end 52a is fixed airtight to the second housing end 51b of the first housing 51, for example by screwing it in. In other words, the second housing 52 is fixed airtight to the first housing 51, for example by screwing it in.

[0033] The fourth housing end 52b is flange-shaped and is fixed to another vacuum pump (e.g., a rotary pump). The internal space on the fourth housing end 52b side of the hollow second housing 52 is the second opening O2. Hereinafter, the direction from the second opening O2 toward the first opening O1 of the first housing 51 will be referred to as the first direction D1.

[0034] A valve support member 52c is positioned in the internal space of the hollow second housing 52. Specifically, the valve support member 52c is positioned in the internal space of the second housing 52 by being fixed to a support portion 52d extending from the inner wall of the second housing 52. Three support portions 52d are provided at equal intervals (equal angles) along the circumferential direction of the second opening O2. The number of support portions 52d can be arbitrary.

[0035] The valve support member 52c has a through hole extending in a first direction D1. The valve shaft of the valve body 54 is inserted into the through hole of the valve support member 52c. The sliding bearing 52e is inserted into the end of the through hole of the valve support member 52c on the first direction D1 side, allowing the valve shaft of the valve body 54 to move smoothly in the first direction D1 or the opposite direction. As shown in Figure 2, since the sliding bearing 52e does not protrude from the end of the valve support member 52c on the first direction D1 side, the valve support member 52c can be made compact.

[0036] Furthermore, since the sliding bearing 52e does not protrude from the first direction D1 side of the valve body support member 52c, when the shut-off valve 50 is in the open state (the state in which the first opening and the second opening are spatially connected), the valve body 54 abuts against the sliding bearing 52e, which increases the distance between the contact surface 54b and the valve seat 53 and thus increases the conductance, and / or, it becomes unnecessary to ensure the size of the housing (second housing 52) that houses the valve body 54 in the first direction D1 in order to ensure a large distance between the contact surface 54b and the valve seat 53.

[0037] A groove is provided at the end of the valve support member 52c opposite to the first direction D1. As will be described later, a biasing member 55 is housed in this groove.

[0038] The valve seat 53 extends from the second housing end 51b of the first housing 51 toward the internal space of the first housing 51 and is positioned between the first opening O1 and the second opening O2. A sealing member Se is provided on the valve seat 53. The sealing member Se is, for example, a rubber O-ring.

[0039] The valve body 54 has a valve body shaft 54a and a contact surface 54b. The valve body shaft 54a is an axis extending in the first direction D1. The valve body shaft 54a is inserted into a through hole in the valve body support member 52c. The valve body 54 is positioned in the internal space of the second housing 52 by the insertion of the valve body shaft 54a into the through hole in the valve body support member 52c. The valve body support member 52c is positioned in the internal space of the second housing 52, that is, on the second opening O2 side of the valve seat 53, and the valve body shaft 54a is inserted into the through hole in this valve body support member 52c, so that the valve body 54 is positioned on the second opening O2 side of the valve seat 53, as shown in Figure 2. The valve body shaft 54a has a first end e1 on the first direction D1 side (first opening O1 side) and a second end e2 on the opposite side of the first direction D1 (second opening O2 side).

[0040] The contact surface 54b is positioned on the side of the second opening O2 that is greater than the first end e1 of the valve body shaft 54a. The contact surface 54b, positioned in this manner, is connected to the first end e1 of the valve body shaft 54a by a connecting portion 54c. In other words, the valve body shaft 54a and the contact surface 54b are connected and integrated by the connecting portion 54c. As a result, the contact surface 54b moves as the valve body shaft 54a moves in the first direction D1 or the opposite direction. When the valve body shaft 54a moves in the first direction D1, the contact surface 54b comes into contact with the valve seat 53 (sealing member Se), thereby spatially separating the first opening O1 and the second opening O2.

[0041] As shown in Figure 2, the length d1 from the contact surface 54b to the first end e1 of the valve body shaft 54a is shorter than the length d2 from the valve seat 53 to the first housing end 51a of the first housing 51 (i.e., the length in the first direction D1 of the first opening O1). As a result, when the contact surface 54b contacts the valve seat 53, the valve body shaft 54a does not protrude from the first opening O1. Although components such as filters may be provided at the exhaust port 16 of the vacuum pump 1, the valve body shaft 54a does not protrude from the first opening O1, which prevents the valve body shaft 54a from damaging the components provided at the exhaust port 16.

[0042] The connecting portion 54c that connects the valve body shaft 54a and the contact surface 54b has a tapered or curved shape. This spatially connects the first opening O1 and the second opening O2, and when exhausting gas from the exhaust port 16 of the vacuum pump 1 to the outside (the vacuum pump connected to the fourth housing end 52b), the conductance for the gas flow from the first opening O1 to the second opening O2 can be increased. As a result, the vacuum pump 1 can be exhausted efficiently.

[0043] The shut-off valve 50 has a biasing member 55. The end of the biasing member 55 on the first opening O1 side is inserted into a groove formed on the second opening O2 side of the valve body support member 52c. A cover member 55a is positioned at the end of the biasing member 55 on the second opening O2 side and is fixed to the second end e2 of the valve body shaft 54a by a screw 55b. As a result, the biasing member 55 is fixed between the valve body support member 52c and the cover member 55a, and can bias the valve body 54 (and its valve body shaft 54a) in the direction opposite to the first direction D1. The biasing member 55 is, for example, a spring member. The biasing force of the biasing member 55 can be appropriately determined, for example, by the amount of backflow of air and pressure difference required to spatially separate the first opening O1 and the second opening O2.

[0044] With the biasing member 55 provided on the shut-off valve 50, the valve body 54, in a normal state (when there is no gas flow in the first direction D1), abuts against the end of the valve body support member 52c on the first direction D1 side, and does not allow the abutment surface 54b to abut against the valve seat 53. In other words, in a normal state, the valve body 54 spatially connects the first opening O1 and the second opening O2.

[0045] The operation of the shut-off valve 50 is described below. When the vacuum pump 1 is driven to evacuate the device to be evacuated, gas flows from the first opening O1 to the second opening O2 (i.e., the normal state), so the biasing force of the biasing member 55 causes the valve body 54 to move to the opposite side of the first direction D1 and come into contact with the end of the valve body support member 52c on the first direction D1 side. As a result, the contact surface 54b of the valve body 54 is spaced apart from the valve seat 53, spatially connecting the first opening O1 and the second opening O2.

[0046] If atmospheric pressure enters the second opening O2 side of the shut-off valve 50 due to a malfunction of the vacuum pump 1 or the like, atmospheric pressure will flow back in the first direction D1 of the shut-off valve 50, and the valve body 54 (for example, the part of the valve body 54 where the contact surface 54b is formed, the cover member 55a, etc.) will be subjected to atmospheric pressure.

[0047] When the pressure acting on the valve body 54 exceeds the biasing force of the biasing member 55, the valve body 54 moves in the first direction D1. When the valve body 54 moves in the first direction D1, as shown in Figure 4, the contact surface 54b of the valve body 54 comes into contact with the valve seat 53, and the first opening O1 and the second opening O2 are spatially separated. By spatially separating the first opening O1 and the second opening O2, backflow of air in the first direction D1 is prevented. As a result, the inflow of air into the vacuum pump 1 can be prevented. Figure 4 shows the shut-off valve 50 in a state where the first opening O1 and the second opening O2 are spatially separated.

[0048] As described above, in the shut-off valve 50 of this embodiment, the contact surface 54b of the valve body 54 that contacts the valve seat 53 of the shut-off valve 50 is positioned on the second opening O2 side of the first end e1 on the first direction D1 side of the valve body shaft 54a of the valve body 54. As a result, compared to conventional shut-off valves in which the contact surface is located at the end on the first direction side of the shaft, the distance between the second end e2 on the opposite side of the first direction D1 side of the valve body shaft 54a and the contact surface 54b can be shortened, so the size of the housing (mainly the second housing 52) that houses the valve body 54 can be made smaller than in conventional designs, and the shut-off valve 50 can be made more compact.

[0049] Furthermore, by positioning the contact surface 54b of the valve body 54 closer to the second opening O2 than the first end e1 of the valve body shaft 54a, the center of gravity of the valve body 54 can be positioned closer to the center of the valve body 54 than the first end e1. This prevents the first end e1 of the valve body shaft 54a from dropping vertically when the shut-off valve 50 is positioned such that the first direction D1, which is the direction of movement of the valve body 54, is horizontal or close to horizontal, as shown in Figure 2. In other words, by positioning the contact surface 54b of the valve body 54 closer to the second opening O2 than the first end e1 of the valve body shaft 54a, the valve body 54 can move smoothly in the first direction D1 or its reverse direction.

[0050] If the contact surface 54b is positioned on the second opening O2 side of the first end e1 of the valve body 54, as shown in Figure 4, when the valve body 54 moves in the first direction D1 and the contact surface 54b contacts the valve seat 53, the first end e1 is positioned on the first opening O1 side of the valve seat 53. If the contact surface is positioned at the first end, as in conventional shut-off valves, even if the valve body shaft is shortened for miniaturization, the distance between the contact surface and the valve seat when the shut-off valve is open becomes small, resulting in small conductance. In other words, it becomes more difficult to efficiently evacuate the vacuum pump 1. To put it another way, by positioning the contact surface 54b on the second opening O2 side of the first end e1 of the valve body 54, the distance between the contact surface 54b and the valve seat 53 when the shut-off valve 50 is open can be increased, thereby increasing the conductance. In other words, the shut-off valve 50 can be miniaturized while efficiently evacuating the vacuum pump 1.

[0051] Furthermore, if the contact surface is located at the first end, as in conventional shut-off valves, even if the valve body shaft is shortened to reduce size, the housing that houses the valve body needs to be larger in order to ensure the distance between the contact surface and the valve seat when the shut-off valve is in the open state. In other words, by positioning the contact surface 54b on the second opening O2 side of the first end e1 of the valve body 54, the housing that houses the valve body 54 (especially the second housing 52) can be made smaller while ensuring a large distance between the contact surface 54b and the valve seat 53 when the shut-off valve 50 is in the open state, thereby increasing the conductance.

[0052] By miniaturizing the shut-off valve 50 installed at the exhaust port 16 of the vacuum pump 1, particularly in the direction from the first opening O1 connected to the exhaust port 16 toward the second opening O2 connected to other piping, etc., it becomes possible to eliminate or minimize the need for design changes to the piping of the vacuum system when installing the shut-off valve 50 in a vacuum pump 1 included in an existing vacuum system. For example, if the shut-off valve is large in the first direction, it becomes necessary to shorten the piping connected to the vacuum pump by cutting or replacing it, or to change the position of the vacuum pump. In addition, adjusting the length of the piping connected to the vacuum pump or changing the position of the vacuum pump can affect other piping, and may necessitate a design change to the entire piping of the vacuum system.

[0053] On the other hand, by making the shut-off valve 50 installed at the exhaust port 16 of the vacuum pump 1 compact, particularly in the first direction D1 from the first opening O1 connected to the exhaust port 16 toward the second opening O2 connected to other piping, the shut-off valve 50 can be attached to the exhaust port 16 of the vacuum pump 1 with, for example, slight movement of the piping connected to the vacuum pump 1 and / or the vacuum pump 1 itself.

[0054] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0055] As shown in Figure 5, the first end e1 of the valve stem 54a of the valve body 54 can be a conical shape, such as a cone shape with its apex facing the first opening O1. This reduces the resistance of the first end e1 to the gas flow compared to the case where the first end e1 is a flat surface. As a result, the viscous flow of the gas can be further improved. Figure 5 shows a modified example of the valve body 54 of the shut-off valve 50.

[0056] Furthermore, even when the first end e1 is conical, it is preferable that the length d1 from the contact surface 54b to the first end e1 be smaller than the length D1 in the first direction of the first opening O1 (the length d2 from the valve seat 53 to the first housing end 51a of the first housing 51). This prevents the first end e1 (the apex of the cone) from protruding from the first opening O1.

[0057] The shut-off valve 50 described above can be used for purposes other than preventing atmospheric intrusion into the vacuum pump 1. For example, it can be inserted into various gas pipes to prevent gas backflow. Furthermore, the biasing force of the biasing member 55 can be appropriately determined according to the various applications.

[0058] Those skilled in the art will understand that the above-described exemplary embodiments are specific examples of the following embodiments.

[0059] (First Embodiment) A shut-off valve (e.g., shut-off valve 50) comprises a valve seat (e.g., valve seat 53) and a valve body (e.g., valve body 54). The valve seat 53 is positioned between a first opening (e.g., first opening O1) and a second opening (e.g., second opening O2). The valve body is positioned on the second opening side of the valve seat and moves from the second opening to the first opening in a first direction (e.g., first direction D1) due to the pressure of the gas flowing from the second opening to the first opening. In this shut-off valve, the valve body has a valve body shaft (e.g., valve body shaft 54a) extending in the first direction and a contact surface (e.g., contact surface 54b) that contacts the valve seat when the valve body moves in the first direction. The contact surface is positioned on the second opening side of the valve body shaft beyond the first end (e.g., first end e1) on the first direction side.

[0060] In the shut-off valve according to the first embodiment, the contact surface of the valve body that abuts against the valve seat of the shut-off valve is positioned on the second opening side of the valve body shaft than the first end on the first direction side of the valve body shaft. As a result, compared to conventional shut-off valves in which the contact surface is positioned at the end on the first direction side of the shaft, the distance between the end on the opposite side of the first direction side of the valve body shaft and the contact surface can be shortened, and the size of the housing that houses the valve body can be reduced compared to conventional designs.

[0061] Furthermore, by positioning the contact surface of the valve body on the second opening side of the valve body shaft beyond the first end, the center of gravity of the valve body can be positioned closer to the center of the valve body than to the first end. This prevents the first end of the valve body from lowering vertically and creating resistance to the movement of the valve body in the first direction when the shut-off valve is positioned so that the first direction of movement of the valve body is horizontal (perpendicular to the vertical direction) or close to it. In other words, by positioning the contact surface of the valve body on the second opening side of the valve body shaft beyond the first end, the valve body can move smoothly in the first direction.

[0062] (Second aspect) In the shut-off valve according to the first aspect, the valve body may have a tapered or curved connecting portion (for example, connecting portion 54c) that connects the contact surface and the first end. In the shut-off valve according to the second aspect, the first opening and the second opening are spatially connected, and when gas flows from the first opening to the second opening, the conductance with respect to the gas flow from the first opening to the second opening can be increased.

[0063] (Third aspect) In the shut-off valve according to the first or second aspect, the first end may have a conical shape. In the shut-off valve according to the third aspect, the resistance to gas flow at the first end of the valve body shaft can be reduced.

[0064] (Fourth aspect) In a shut-off valve according to any of the first to third aspects, the length from the contact surface to the first end (for example, length d1) may be shorter than the length of the first opening in the first direction (for example, length d2). In the shut-off valve according to the fourth aspect, the valve body shaft does not protrude from the first opening when the contact surface contacts the valve seat, so that the valve body shaft 54a does not damage a member provided near the first opening.

[0065] (Fifth Embodiment) The vacuum pump (for example, vacuum pump 1) comprises a shut-off valve according to any of the first to fourth embodiments, and an exhaust port (for example, exhaust port 16) connected to the first opening of the shut-off valve. In the vacuum pump according to the fifth embodiment, the shut-off valve provided at the exhaust port of the vacuum pump is miniaturized in the direction from the first opening connected to the exhaust port toward the second opening on the opposite side. In the vacuum pump according to the fifth embodiment, when the shut-off valve is provided in an existing vacuum system including the vacuum pump, the design changes to the piping of the vacuum system can be made unnecessary or minimized. [Explanation of Symbols]

[0066] 1: Vacuum pump 2: Cabinet 3: Rotor 4: Motor 5: Stator wing unit 6: Stator cylindrical section 8: Casing 9: Bass 10: Fixed flange 11:First end 12:Second end 13: Side part 14: Air intake 15: Base end 16: Exhaust vent 20: Bolt 21: Shaft 22: Rotor blade unit 23: Rotor cylindrical section 24A-24C: Bearing 25: Rotor blades 26: Motor Rotor 27: Motor Stator 28: Stator Wing 29: Protective bearing P1: Turbine section P2: Drag pump section S1: 1st internal space S2:Second internal space 50: Shut-off valve 51: Housing No. 1 51a: First housing end 51b: Second housing end O1: First opening 52: Second Housing 52a: Third housing end 52b: Fourth housing end 52c: Valve body support member 52d: Support part 52e: Plain bearing O2: 2nd opening 53: Alveolar seat Se: Sealing component 54: Valve body 54a: Valve axis e1 :1st end e2: 2nd end 54b: Contact surface 54c: Connection part 55: Biasing member 55a: Lid member 55b: Screw D1: 1st direction

Claims

1. A valve seat positioned between the first opening and the second opening, A valve body is positioned on the second opening side of the valve seat and moves in a first direction from the second opening to the first opening due to the pressure of the gas flowing from the second opening to the first opening, Equipped with, The valve body is, The valve shaft extending in the first direction, A contact surface that contacts the valve seat when the valve body moves in the first direction, It has, The contact surface is positioned on the second opening side of the valve body shaft, rather than on the first end on the first direction side. Shut-off valve.

2. The shut-off valve according to claim 1, wherein the valve body has a tapered or curved connecting portion that connects the contact surface and the first end.

3. The shut-off valve according to claim 1, wherein the first end has a conical shape.

4. The shut-off valve according to claim 1, wherein the length from the contact surface to the first end is shorter than the length of the first opening in the first direction.

5. A shut-off valve according to any one of claims 1 to 4, An exhaust port connected to the first opening of the shut-off valve, A vacuum pump equipped with the following features.

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