vacuum pump

Abstract

To provide a vacuum pump that can suppress damage on a component to be connected to external piping even when deviation in a rotation direction occurs in the vacuum pump due to damage of the vacuum pump, thereby suppressing gas leakage, and to provide a piping structure part for a vacuum pump.SOLUTION: A vacuum pump 1 for sucking a gas from an intake port with the rotation of a rotor includes: a casing 4 for storing a rotor 3 so as to be rotatable; and a piping structure part 100 disposed in the casing 4. At least part of the piping structure part 100 includes an elastic part capable of absorbing displacement by elastically deforming.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Semiconductor manufacturing equipment, liquid crystal manufacturing equipment, electron microscopes, surface analysis equipment, microfabrication equipment, and the like require the environment within the equipment to be kept at a high vacuum. Vacuum pumps are used to create a high vacuum within these devices. Vacuum pumps rotate rotor blades relative to stator blades to exhaust gas to the outside, thereby maintaining a high vacuum within the above-mentioned devices.

[0003] However, during operation of a vacuum pump, a problem may occur, causing the rotor, which is rotating at high speed, to collide with a stationary member such as a stator, which is not rotating. In this case, the momentum of the rotor is transferred to the stationary member, and a torque is generated instantaneously, which rotates the entire vacuum pump in the direction of the rotor's rotation. The instantaneously generated excessive torque also exerts a large stress on the vacuum vessel through the flange. For this reason, Patent Document 1 discloses a vacuum pump in which a thin-walled portion is provided in the flange where the suction port is formed, and the thin-walled portion is plastically deformed to absorb part of the energy of the excessive torque. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4484470 specification Summary of the Invention [Problem to be solved by the invention]

[0005] The vacuum pump described in Patent Document 1 can absorb displacement on the intake side, but cannot absorb displacement in piping other than the intake. For example, the piping that forms the exhaust port, purge port, and vent port may become misaligned with the external piping due to a deviation in the rotation direction of the vacuum pump, which could cause internal gas leakage.

[0006] The present invention has been made to solve the above-mentioned problems, and provides a vacuum pump that can suppress damage to parts connected to external piping and suppress gas leakage even if a deviation in the rotation direction of the vacuum pump occurs due to damage to the vacuum pump. P The purpose is to provide. [Means for solving the problem]

[0007] To achieve the above object, the vacuum pump according to the present invention is a vacuum pump that sucks gas from an intake port by rotating a rotor, and the rotor is rotatably accommodated. and located at the edge Gas is poured into the open end of the cylindrical Aspirate The intake port is formed in a casing, and the casing includes an exhaust port or a purge port, which is located radially outward from the center of rotation and is subject to rotational deviation due to damage during operation. Extends to the outer flange at the end Piping structure Department The piping structure The department , formed in a tubular shape from a metal material that can absorb displacement through elastic deformation. a bellows structure including a portion and a cylindrical portion that enters a flow path of the casing; Equipped with ,before At least a portion of the piping structure along the central axis thereof is formed solely by the bellows structure. [Effects of the Invention]

[0008] In the vacuum pump configured as described above, if displacement occurs due to damage during operation, the elastic portion elastically deforms, thereby preventing displacement of the portion of the piping structure connected to the external piping. This prevents damage to the parts connecting the piping structure to the external piping, and prevents leakage of gas flowing through the piping structure.

[0009] The direction of protrusion of the piping structure from the casing may have a radial component of the rotor. If the piping structure does not have an elastic portion, a positional shift of the connection portion of the piping structure with the external piping is likely to occur due to a shift in the rotational direction of the vacuum pump. However, by providing the elastic portion to the piping structure, it is possible to effectively suppress positional shift of the connection portion of the piping structure with the external piping.

[0010] The direction of protrusion of the piping structure from the casing may have a directional component in the axial direction of the rotor, and the axial center of the piping structure may be disposed at a position displaced radially from the axial center of the rotor. In this way, if the piping structure does not have an elastic portion, a positional displacement of the connection portion of the piping structure with the external piping is likely to occur due to a misalignment in the rotational direction of the vacuum pump. However, by providing the elastic portion in the piping structure, it is possible to effectively suppress the positional displacement of the connection portion of the piping structure with the external piping.

[0011] The piping structure has a bellows structure. do As a result, the bellows structure can effectively prevent misalignment of the connection portion between the piping structure and the external piping, and can effectively prevent leakage of gas flowing through the piping structure.

[0012] The piping structure may have an inner surface formed from polytetrafluoroethylene.

[0013] The piping structure is an exhaust port. R This makes it possible to effectively prevent leakage of exhaust gas flowing through the piping structure portion, which is the exhaust port, by the elastically deformable piping structure portion. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing a vacuum pump according to a first embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the vicinity of a piping structure of a vacuum pump. [Figure 3] 10 is a cross-sectional view of the vicinity of a piping structure of a vacuum pump, showing a first modified example of the piping structure. FIG. [Figure 4]FIG. 10 is a cross-sectional view of the vicinity of a piping structure of a vacuum pump, showing a second modified example of the piping structure. [Figure 5] FIG. 10 is a cross-sectional view showing the vicinity of a piping structure of a vacuum pump according to a second embodiment. [Figure 6] 10A and 10B are cross-sectional views of the piping structure of a vacuum pump according to a second embodiment at a position where a bolt is inserted, in which (A) shows the state before the inside of the piping structure becomes negative pressure, and (B) shows the state when the inside of the piping structure becomes negative pressure. [Figure 7] FIG. 10 is a plan view of a vacuum pump showing another application example of a piping structure portion. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that dimensions in the drawings may be exaggerated for convenience of explanation and may differ from actual dimensions. Furthermore, in this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0021] First Embodiment

[0022] 1, a vacuum pump 1 according to a first embodiment of the present invention is a turbomolecular pump that exhausts gas by ejecting gas molecules as a rotor 3 equipped with rotor blades 32 rotates at high speed. The vacuum pump 1 has a vacuum pump main body 2 for sucking in and exhausting gas, and a control device 5 for controlling the vacuum pump main body 2. The vacuum pump 1 is used to suck in and exhaust gas from a chamber of, for example, a semiconductor manufacturing device.

[0023] The vacuum pump body 2 has a rotatable rotor 3, a casing 4 that rotatably surrounds the rotor 3, and a piping structure 100 that is disposed in the casing 4 and serves as an exhaust port. The vacuum pump body 2 further has a bearing that rotatably supports the rotor 3, a displacement sensor that detects the displacement of the rotor 3, and a motor 80 (drive unit) that rotationally drives the rotor 3.

[0024] The casing 4 has a cylindrical first casing 10 in which an intake port 11 is formed, a second casing 20 to which a piping structure section 100 serving as an exhaust port is connected, a stator column 22 fixed to the second casing 20, a stator blade section 40, and a threaded spacer 90.

[0025] The first casing 10 is located at the top of the vacuum pump body 2, and has an intake port 11 formed at its upper end. The first casing 10 is fixed by bolts 12 to the second casing 20 disposed at the bottom thereof.

[0026] The rotor 3 is rotatably disposed inside the first casing 10. The rotor 3 has a shaft 35, multiple stages of rotor blades 32 in the axial direction, and a cylindrical portion 33 disposed downstream of the rotor blades 32. The rotor blades 32 constitute a turbomolecular pump and are blades for sucking and exhausting gas. The multiple rotor blades 32 in each stage are arranged radially in the circumferential direction.

[0027] The rotor 3 has a substantially cylindrical shape, with the shaft 35 passing through and fixed inside. Each rotor vane 32 is formed at an angle at a predetermined angle from a plane perpendicular to the axial direction of the shaft 35 in order to transport exhaust gas molecules downward through collision. The rotor vanes 32 are formed integrally with the outer circumferential surface of the rotor 3. Alternatively, the rotor vanes 32 may be fixed to the outer circumferential surface of the rotor 3.

[0028] The cylindrical portion 33 is disposed downstream of the rotor blades 32 and is formed in a cylindrical shape. The cylindrical portion 33 is formed to protrude toward the inner peripheral surface of the threaded spacer 90. The cylindrical portion 33 is adjacent to the inner peripheral surface of the threaded spacer 90 with a predetermined gap therebetween.

[0029] The shaft 35 is disposed at the center of rotation of the rotor 3. The shaft 35 has a cylindrical main shaft portion 36 and a circular disk 37 disposed below the main shaft portion 36. The main shaft portion 36 and the disk 37 are formed of a highly magnetically permeable material (iron, etc.) that can be attracted by magnetism. The main shaft portion 36 is attracted and its position is controlled by the magnetic forces of an upstream radial electromagnet 61 and a downstream radial electromagnet 62, which will be described later.

[0030] The bearing is, for example, a so-called five-axis controlled magnetic bearing, which levitates and supports the shaft 35 and controls its position. The bearing has an upstream radial electromagnet 61 that attracts the upstream side of the main shaft portion 36, a downstream radial electromagnet 62 that attracts the downstream side of the main shaft portion 36, axial electromagnets 63A and 63B that attract the disk 37, and an auxiliary bearing 65. Auxiliary bearing 65 comes into contact with the main shaft portion 36 when the axial runout of the rotor 3 becomes large, preventing the rotor 3 from coming into direct contact with the stator and being damaged.

[0031] The upstream radial electromagnet 61 has four electromagnets arranged in pairs on each of two axes orthogonal to a plane perpendicular to the rotation axis. The downstream radial electromagnet 62 has four electromagnets arranged in pairs on each of two axes orthogonal to a plane perpendicular to the rotation axis. The axial electromagnets 63A and 63B are arranged to sandwich the disk 37 from above and below.

[0032] The displacement sensors are arranged on the stator column 22 to detect the displacement of the rotor 3. The displacement sensors include an upstream radial sensor 71, a downstream radial sensor 72, and an axial sensor 73. The upstream radial sensors 71 are four non-contact sensors arranged in proximity to and corresponding to the four upstream radial electromagnets 61. The upstream radial sensors 71 are configured to detect the radial displacement of the upper part of the main shaft portion 36 of the shaft 35 and transmit the displacement signal to the control device 5. Examples of sensors used as the upstream radial sensors 71 include inductance sensors and eddy current sensors.

[0033] The downstream radial sensors 72 are four non-contact sensors arranged in proximity to and corresponding to the four downstream radial electromagnets 62. The downstream radial sensors 72 are configured to detect radial displacement of the lower part of the main shaft portion 36 and transmit a displacement signal to the control device 5. Examples of sensors used as the downstream radial sensors 72 include an inductance sensor and an eddy current sensor.

[0034] The axial sensor 73 is disposed below the disk 37. The axial sensor 73 is configured to detect the axial displacement of the shaft 35 and transmit a displacement signal to the control device 5.

[0035] Based on the displacement signal detected by the upstream radial sensor 71, the control device 5 controls the excitation of the upstream radial electromagnet 61 via a compensation circuit having a PID adjustment function, thereby adjusting the upstream radial position of the main shaft portion 36. This adjustment is performed independently for each of two axes that are orthogonal to each other in a plane perpendicular to the rotation axis.

[0036] Furthermore, the control device 5 controls the excitation of the downstream radial electromagnet 62 via a compensation circuit having a PID adjustment function based on the displacement signal detected by the downstream radial sensor 72, thereby adjusting the radial position of the downstream side of the main shaft portion 36. This adjustment is performed independently for each of two axes that are orthogonal to each other in a plane perpendicular to the rotation axis.

[0037] Furthermore, the control device 5 controls the excitation of the axial electromagnets 63A and 63B based on the displacement signal detected by the axial sensor 73. At this time, the axial electromagnet 63A attracts the disk 37 upward by magnetic force, and the axial electromagnet 63B attracts the disk 37 downward. In this way, by appropriately adjusting the magnetic force exerted on the shaft 35, the magnetic bearing can magnetically levitate the shaft 35 and support it rotatably without contact.

[0038] The motor 80 has magnetic poles 81, which are multiple permanent magnets arranged on the rotor side, and motor electromagnets 82 arranged on the stator side. A torque component that rotates the shaft 35 is applied to the magnetic poles 81 from the motor electromagnets 82. This causes the rotor 3 to rotate.

[0039] The motor 80 is also equipped with a rotation speed sensor and a motor temperature sensor (not shown). The rotation speed sensor and the motor temperature sensor transmit the results of their detection as detection signals to the control device 5. The control device 5 uses the signals received from the rotation speed sensor and the motor temperature sensor to control the rotation of the shaft 35.

[0040] The stator blade section 40 has multiple stages of stators 41 and a plurality of stator spacers 42 stacked so as to sandwich each stage of the stators 41. Each stator 41 has a plurality of stator blades 43.

[0041] Like the rotor blades 32, the stator blades 43 are formed to be inclined at a predetermined angle from a plane perpendicular to the axial direction of the shaft 35. The stator blades 43 are arranged inward of the first casing 10, alternately arranged with the rows of the rotor blades 32. The outer peripheral ends of the stator blades 43 are supported by being sandwiched between a plurality of stacked ring-shaped stator spacers 42. The stator spacers 42 are arranged in a stacked manner inside the first casing 10. The stator spacers 42 are made of a metal such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals as an ingredient.

[0042] The threaded spacer 90 is disposed between the lower part of the stator spacer 42 and the second casing 20. The threaded spacer 90 is adjacent to the cylindrical portion 33 of the rotor 3, which is disposed cylindrically, with a predetermined gap between them. A plurality of spiral thread grooves 91 are formed on the inner peripheral surface of the threaded spacer 90. The spiral direction of these thread grooves 91 corresponds to the direction in which exhaust gas molecules are transported toward the exhaust port when they move in the rotational direction of the rotor 3. The threaded spacer 90 and the cylindrical portion 33 constitute a threaded pump. The threaded spacer 90 is made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals.

[0043] The second casing 20 is a disk-shaped member that forms the bottom of the vacuum pump main body 2. The second casing 20 has a piping structure 100 connected to the bottom of a threaded spacer 90. The second casing 20 is generally made of a metal such as iron, aluminum, or stainless steel. The second casing 20 preferably not only physically holds the vacuum pump main body 2 but also functions as a heat conduction path. Therefore, the material that forms the second casing 20 is preferably a metal that is rigid and has high thermal conductivity, and suitable materials that can be used include iron, aluminum, copper, etc.

[0044] As shown in FIG. 2, the piping structure 100 is an exhaust port that exhausts exhaust gas to the external piping 200. The piping structure 100 has a flow path formed therein through which the exhaust gas flows, and is formed in a generally cylindrical shape as a whole. The piping structure 100 is connected to a side wall surface of the second casing 20 of the casing 4, and protrudes from the second casing 20 in the radial direction of the rotor 3. The piping structure 100 has a main body flange 101 connected to the casing 4, an external flange 102 connected to the external piping 200, a tubular portion 103 provided between the main body flange 101 and the external flange 102, and a cylindrical portion 108.

[0045] The main body flange 101 is fixed to the casing 4 via an O-ring 104. The main body flange 101 is fixed to the casing 4 by, for example, bolts 105, but the fixing method is not particularly limited. The O-ring 104 plays a role in maintaining a vacuum inside the piping structure 100.

[0046] The external flange 102 is located on the opposite side of the main body flange 101, and is fixed to the flange of the external pipe 200 via, for example, a known O-ring 106 with a center ring. The external flange 102 and the flange of the external pipe 200 are fastened and fixed together, for example, by a known clamp 107. Note that the method for fixing the external flange 102 and the flange of the external pipe 200 is not particularly limited, and they may be fixed together, for example, by bolts or the like.

[0047] The tubular portion 103 has a bellows structure and is made up of a flexibly deformable elastic portion. The bellows structure of the tubular portion 103 allows it to elastically expand and contract in the flow path direction of the piping structure portion 100 (radial direction of the rotor 3) and also allows it to elastically bend in any direction.

[0048] The material of the piping structure 100 is not particularly limited as long as the bellows structure can be elastically deformed and the main flange 101 and the external flange 102 can be appropriately attached to the attachment target, but suitable materials include metal materials such as stainless steel and polymer materials such as polytetrafluoroethylene (PTFE). If at least the inner surface of the piping structure 100 is made of PTFE, the corrosion resistance of the piping structure 100 can be improved.

[0049] The cylindrical portion 108 is a cylindrical portion that protrudes further toward the casing 4 than the main body flange 101. The cylindrical portion 108 is disposed so as to fit into the hole 24 of the flow path provided in the casing 4.

[0050] In the vacuum pump main body 2 described above, when the shaft 35 is driven by the motor 80, the rotor blades 32 and the cylindrical portion 33 rotate. As a result, exhaust gas from the chamber is drawn in through the intake port 11 by the action of the rotor blades 32 and the stator blades 43.

[0051] The exhaust gas taken in through the intake port 11 is transferred to the second casing 20 by the rotor blades 32 and the stator blades 43. At this time, the temperature of the rotor blades 32 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor blades 32, conduction of heat generated by the motor 80, and the like. However, this heat is transferred to the stator blades 43 by radiation or conduction by gas molecules in the exhaust gas. Furthermore, the stator spacers 42 are joined to each other at their outer peripheries. Therefore, the heat received by the stator blades 43 from the rotor blades 32 and frictional heat generated when the exhaust gas comes into contact with the stator blades 43, and the like are transferred to the outside via the stator spacers 42.

[0052] Furthermore, the exhaust gas transferred to the second casing 20 is guided by the thread groove 91 of the threaded spacer 90, and then transferred to the piping structure 100, which is an exhaust port. In this embodiment, the threaded spacer 90 is disposed on the outer periphery of the cylindrical portion 33, and the thread groove 91 is formed on the inner circumferential surface of the threaded spacer 90. However, conversely, a thread groove may be formed on the outer circumferential surface of the cylindrical portion 33, and a spacer having a cylindrical inner circumferential surface may be disposed around it.

[0053] The outer periphery of the electrical equipment is covered by the stator column 22 to prevent gas drawn in from the intake port 11 from entering the electrical equipment side, which is composed of the motor 80, downstream radial electromagnet 62, downstream radial sensor 72, upstream radial electromagnet 61, upstream radial sensor 71, etc. The interior of the stator column 22 surrounding the electrical equipment is maintained at a predetermined pressure by purge gas. Pipes (not shown) are arranged in the second casing 20, and purge gas is introduced through these pipes. The introduced purge gas is sent to the piping structure 100, which serves as an exhaust port, through gaps between the auxiliary bearing 65 and the shaft 35, between the motor 80, and between the stator column 22 and the rotor blades 32.

[0054] A heater (not shown) and a circular water-cooled pipe 23 are wound around the outer periphery of the second casing 20, etc. Furthermore, a temperature sensor (e.g., a thermistor) (not shown) is embedded in the second casing 20. Based on a signal from this temperature sensor, heating by the heater and cooling by the water-cooled pipe 23 are controlled so as to maintain the temperature of the second casing 20 at a constant high temperature (set temperature). This prevents process gas from adhering to and accumulating inside the vacuum pump main body 2.

[0055] Process gases are sometimes introduced into the chamber at high temperatures to enhance their reactivity. These process gases cool to a certain temperature as they are exhausted, and solidify, sometimes resulting in the deposition of products in the exhaust system. When this type of process gas cools down inside the vacuum pump body 2, it solidifies and adheres to and accumulates inside the vacuum pump body 2.

[0056] For example, when SiCl4 is used as the process gas in an Al etching system, the low vacuum (1×10 5 At a pressure of 1000 Pa to 1 Pa and a low temperature (approximately 20°C), solid products (e.g., AlCl3) precipitate and accumulate inside the vacuum pump body 2. If process gas deposits accumulate inside the vacuum pump body 2, the deposits narrow the pump flow path, causing a decrease in the performance of the vacuum pump body 2. For example, the above-mentioned products tend to solidify and adhere to low-temperature areas near the exhaust port, particularly near the cylindrical portion 33 and the threaded spacer 90. Therefore, based on the signal from the temperature sensor, the control device 5 controls the heating of the heater and the cooling by the water-cooled pipe 23 to maintain the temperature of the second casing 20 at a constant high temperature (set temperature). This makes it possible to prevent the process gas from adhering to and accumulating inside the vacuum pump body 2.

[0057] During operation of the vacuum pump 1, a problem may occur, causing the rotor 3, which is rotating at high speed, to collide with a stationary member, such as the stator 41, which is not rotating. In this case, the momentum of the rotor 3 is transferred to the stationary member, causing the entire vacuum pump 1 to instantaneously rotate in the direction of rotation of the rotor 3. At this time, the piping structure 100, having an elastically deformable bellows structure, absorbs any positional deviation caused by the rotation. Therefore, the position of the external flange 102 connected to the external pipe 200 does not move or the movement is reduced. As a result, damage to the clamp 107 connecting the external flange 102 and the flange of the external pipe 200 is suppressed, and leakage of exhaust gas from within the piping structure 100 is suppressed. Furthermore, because the piping structure 100 can absorb displacement in directions other than the rotational direction of the rotor 3, damage to the clamp 107 is more effectively suppressed, and leakage of exhaust gas from within the piping structure 100 is more effectively suppressed.

[0058] As described above, the vacuum pump 1 according to the first embodiment is a vacuum pump 1 that draws gas from an intake port by rotating a rotor, and has a casing 4 that rotatably houses the rotor 3, and a piping structure 100 arranged in the casing 4, and at least a part of the piping structure 100 has an elastic part that can absorb displacement by elastic deformation.

[0059] In the vacuum pump 1 configured as described above, if displacement (mainly in the rotational direction) occurs due to damage during operation, the bellows structure (elastic portion) elastically deforms, thereby preventing displacement of the portion of the piping structure 100 connected to the external piping 200. This prevents damage to the parts connecting the piping structure 100 and the external piping 200, and prevents leakage of gas flowing through the piping structure 100.

[0060] Furthermore, the direction in which the piping structure 100 protrudes from the casing 4 has a radial component of the rotor 3. As a result, if the piping structure 100 does not have an elastic portion, the connection portion of the piping structure 100 with the external piping 200 is likely to be located radially outward of the rotor 3 due to a deviation in the rotational direction of the vacuum pump 1, and misalignment is likely to occur. However, by providing an elastic portion in the piping structure 100, it is possible to effectively suppress misalignment of the connection portion of the piping structure 100 with the external piping 200. The direction in which the piping structure 100 protrudes from the casing 4 may be parallel to the radial direction of the rotor 3 or may be inclined relative to the radial direction of the rotor 3.

[0061] Furthermore, the piping structure 100 has a bellows structure, which can effectively prevent misalignment of the connection portion of the piping structure 100 with the external piping 200, and can effectively prevent leakage of gas flowing through the piping structure 100.

[0062] Furthermore, the piping structure 100 is an exhaust port. This makes it possible to effectively prevent leakage of exhaust gas flowing through the piping structure 100, which is an exhaust port, by the elastically deformable piping structure 100.

[0063] As a first modification of the first embodiment, as shown in FIG. 3 , the piping structure 100 may have a main flange 101 and an external flange 102 formed of a highly rigid material, and a tubular portion 103 having a bellows structure and intended to be elastically deformable formed of a flexible polymeric material. The highly rigid material may be, for example, a metal material such as stainless steel. The flexible polymeric material may be, for example, polytetrafluoroethylene (PTFE), silicone rubber, or the like. Furthermore, a flexible material that can withstand a vacuum may be, for example, a composite material in which a flexible material is reinforced with wire or the like. Forming at least the inner surface of the piping structure 100 from PTFE can improve the corrosion resistance of the piping structure 100. The method of joining the main flange 101 and the external flange 102 to the tubular portion 103 is not particularly limited. For example, the tubular portion 103 may be pressed against the main flange 101 or the external flange 102 by adhesive bonding or a ring-shaped crimping member 109 surrounding the outside of the tubular portion 103. Even with the piping structure 100 having such a structure, the rotational deviation of the vacuum pump 1 can be effectively absorbed by the elastically deformable tubular portion 103. The piping structure 100 having such a structure can be well connected to the casing 4 and the external piping 200 by the main body flange 101 and the external flange 102, which have high rigidity, and can also improve the flexibility of the tubular portion 103 having a bellows structure.

[0064] As a second modification of the first embodiment, as shown in FIG. 4, the piping structure 100 may have the main body flange 101 and the external flange 102 formed from a highly rigid material, and the tubular portion 103, which is intended to be elastically deformed, formed from a flexible, cylindrical material. In other words, the piping structure 100 does not have a bellows structure. Note that the materials described in the first modification can be applied to the main body flange 101, the external flange 102, and the tubular portion 103. Even with the piping structure 100 having such a structure, deviations in the rotational direction of the vacuum pump 1 can be effectively absorbed by the elastically deformable tubular portion 103.

[0065] Second Embodiment

[0066] The vacuum pump 1 according to the second embodiment differs from the first embodiment only in the structure of the piping structure 110. While the piping structure 100 in the first embodiment includes an elastic portion in the piping itself, the piping structure 110 in the second embodiment has an elastic portion as a structure separate from the piping 120.

[0067] As shown in Figures 5 and 6(A), the piping structure 110 in the second embodiment has a piping 120, an elastic part 130 (elastic part) made of an elastic material, a movement restricting part 140 that restricts the amount of separation of the piping 120 from the casing 4 within a predetermined range, a first O-ring 150, and a second O-ring 151.

[0068] The piping 120 has a main body flange 121 connected to the casing 4, an external flange 122 connected to the external piping 200, a tubular portion 123 provided between the main body flange 121 and the external flange 122, and a cylindrical portion 125.

[0069] The main body flange 121 contacts the elastic element 130 via a first O-ring 150. The main body flange 121 has multiple through holes 124 through which the movement restricting portion 140 passes. The external flange 122 is located on the opposite side of the main body flange 121 and is fixed to the flange of the external pipe 200 via a centering O-ring 106. The external flange 122 and the flange of the external pipe 200 are fastened and fixed together, for example, with a clamp 107. Note that the method for fastening the external flange 122 and the flange of the external pipe 200 is not particularly limited. The tubular portion 123 has a circular tubular shape and is formed integrally with the main body flange 121 and the external flange 122. The material of the pipe 120 is not particularly limited, but may be a metal material such as stainless steel. The cylindrical portion 125 is a cylindrical portion that protrudes toward the casing 4 beyond the main body flange 121. The cylindrical portion 125 is disposed by fitting into the hole 24 of the flow path provided in the casing 4.

[0070] The elastic element 130 is a member made of an elastic material and sandwiched between the outer surface of the casing 4 and the surface of the main body flange 121 facing the casing 4. The elastic element 130 contacts the outer surface of the casing 4 with a second O-ring 151 sandwiched therebetween. The elastic element 130 is formed with a substantially uniform thickness between the casing 4 and the main body flange 121 and has a through-hole 131 through which the movement restrictor 140 passes. The elastic material constituting the elastic element 130 is not particularly limited, but is required to be corrosion-resistant and heat-resistant, and therefore, examples of the elastic material include silicone resin. The elastic material constituting the elastic element 130 is preferably slightly softer than the first O-ring 150 and the second O-ring 151. If the elastic material is too soft, the first O-ring 150 and the second O-ring 151 will not collapse, making it difficult to maintain negative pressure inside the piping structure 110. The material constituting the first O-ring 150 and the second O-ring 151 is not particularly limited, but is, for example, a fluororesin. If the elastic member constituting elastic element 130 has a large longitudinal elastic modulus in the longitudinal direction of the exhaust port and a small transverse elastic modulus in the direction perpendicular thereto, it will be easier to absorb bending displacement that occurs at the exhaust port, i.e., displacement that tilts piping 120. Note that if elastic element 130 can maintain the negative pressure inside piping structure 110, first O-ring 150 and second O-ring 151 do not need to be provided.

[0071] The movement restricting portion 140 has a cylindrical movement restricting sleeve 141 and a movement restricting bolt 142. The movement restricting sleeve 141 passes through the through hole 131 of the elastic component 130 and the through hole 124 of the main body flange 121. The outer peripheral surface of the movement restricting sleeve 141 has a clearance with the through hole 131 and the through hole 124. One end of the movement restricting sleeve 141 abuts against the outer surface of the casing 4, and the opposite end has a restricting abutment portion 143 with an expanding outer diameter. The restricting abutment portion 143 abuts against the surface of the main body flange 121 that is away from the casing 4, and restricts the distance of the piping 120 from the casing 4 within a predetermined range.

[0072] The movement restricting bolt 142 penetrates the inside of the movement restricting sleeve 141 from the side farther from the casing 4, and is fixed to a threaded hole 144 formed on the outer surface of the casing 4. In this way, the movement restricting bolt 142 fixes the movement restricting sleeve 141 to the casing 4.

[0073] The first O-ring 150 and the second O-ring 151 play a role in maintaining the negative pressure inside the piping structure 110 .

[0074] When the vacuum pump 1 is activated, a negative pressure is created inside the piping structure 110. As a result, as shown in FIG. 6(B), the piping 120 moves closer to the outer surface of the casing 4 while deforming the elastic element 130. As a result, the main body flange 121 moves away from the restricting abutment 143. At this time, since the movement restricting sleeve 141 passes through the through holes 131 and 124 with a clearance, the piping 120 is flexibly supported by the elastic element 130 and is allowed to move toward and away from the casing 4. In addition, the cylindrical portion 125 of the piping 120 on the casing 4 side has a slight gap with the inner circumferential surface of the flow path hole 24 provided in the casing 4. In this state, if a problem occurs in the vacuum pump 1 and the entire vacuum pump 1 rotates instantaneously in the rotational direction of the rotor 3, the piping 120, which is movably supported by each movement restriction part 140, can move toward or away from the casing 4 within a predetermined range while deforming the elastic parts 130, and can tilt to absorb the movement in the rotational direction. This makes it possible to prevent damage to the parts connecting the piping structure part 110 and the external piping 200, and to prevent leakage of gas flowing through the piping structure part 110.

[0075] As described above, in the second embodiment, the elastic portion is configured by the elastic element 130 made of an elastic material, and is disposed by being sandwiched between the pipe 120 provided in the piping structure 110 and the casing 4. As a result, the elastic element 130 can effectively suppress misalignment of the connection portion of the piping structure 110 with the external pipe 200, and can effectively suppress leakage of gas flowing through the piping structure 110.

[0076] The present invention is not limited to the above-described embodiment, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. For example, as shown in FIG. 7, the piping structure 100 having an elastic portion may protrude with a component in a direction X parallel to the rotation axis of the rotor 3. The protruding direction of the piping structure 100 may be parallel to or tilted from the direction X. The axial center of the piping structure 100 is spaced radially from an extension of the axial center of the rotor 3. In this case, if the piping structure does not include an elastic portion, the connection portion of the piping structure with the external piping is likely to become misaligned due to a shift in the rotation direction of the vacuum pump 1. However, by providing an elastic portion in the piping structure 100, misalignment of the connection portion of the piping structure 100 with the external piping can be effectively suppressed. As shown in FIG. 7, the central axis of the piping structure 100A may be located on an extension of the rotation axis of the rotor 3.

[0077] The piping structure unit can also provide the same effect when applied to the purge port 160 that supplies purge gas to the vacuum pump 1. The piping structure unit can also provide the same effect when applied to a vent port that releases pressure inside the vacuum pump 1. [Explanation of symbols]

[0078] 1. Vacuum pump 3 rotors 4 Casing 100, 110 Piping structure section 101, 121 Body flange 102, 122 External flange 103, 123 tubular part 130 Elastic parts (elastic parts) 200 External piping

Claims

1. A vacuum pump that draws gas from an intake port by rotating a rotor, a casing that rotatably houses the rotor, the casing having a cylindrical opening at an end thereof that is formed with the intake port for sucking gas, and that is susceptible to deviation in rotational direction due to damage during operation; a piping structure portion that is an entire structure including an exhaust port or a purge port disposed in the casing and extending from a rotation center to an external flange that is an end portion located radially outward; the piping structure portion includes a bellows structure including a portion formed in a tubular shape from a metal material capable of absorbing displacement by elastic deformation, and a cylindrical portion that enters a flow path of the casing, A vacuum pump, wherein at least a portion of the piping structure along the central axis thereof is formed solely by the bellows structure.

2. 2. The vacuum pump according to claim 1, wherein the direction in which the piping structure portion protrudes from the casing has a component in the radial direction of the rotor.

3. a protruding direction of the piping structure portion from the casing has a direction component in the axial direction of the rotor, 2. The vacuum pump according to claim 1, wherein an axial center of the piping structure is disposed at a position radially shifted from an axial center of the rotor.

4. 4. The vacuum pump according to claim 1, wherein the piping structure has an inner surface made of polytetrafluoroethylene.

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