JP2009092041A - Cantilever rotary pump - Google Patents

Abstract

A structure for supporting a rotating rotor on a rotating shaft that can cope with expansion and contraction due to thermal expansion accompanying rotation and that is simple in structure and easy to disassemble and assemble is obtained.
A rotor is rotatably disposed in an exhaust chamber provided in a housing via a bearing provided only at one shaft end, and a gas transfer chamber is formed by the inner wall of the housing and the rotor. In a cantilever rotary pump in which an intake port and an exhaust port communicating with a chamber are formed in a housing, and gas is sucked into the transfer chamber from the intake port and gas is discharged from the exhaust port, the rotor has a hollow shaft and a rotary shaft. In this structure, the shaft end of the member is fixed, and the rotating shaft member and the rotor member are integrally fixed via a cylindrical member.
[Selection] Figure 1

Description

  The present invention facilitates alignment when the rotor member of the cantilever rotor used for the rotary pump is supported on the rotary shaft member, and can cope with expansion and contraction of the rotor member and the rotary shaft member due to thermal expansion accompanying rotation, In addition, the present invention relates to the structure of a cantilever rotor type rotary pump that is easy to manufacture, disassemble and assemble and can rotate at high speed. Particularly, it is suitable for a structure in which the rotor is cantilevered and the rotation axis is held vertically, such as a turbo molecular pump, a thread groove type pump, or a screw type pump having one or three rotors.

Conventionally, as a method of constructing a cantilever rotor by fixing and integrating a rotor member, which is a separate member, to the rotary shaft members 10 and 11, the diameter increases as the tip ends of the rotary shaft members 10 and 11 are approached as shown in FIG. Tapering portions 15 and 17 that become thinner and have the same taper angle as that of the rotary shaft members 10 and 11 at the portions where the rotary shaft insertion hollow portions of the rotor members 13 and 14 are in pressure contact with the rotary shaft members 10 and 11. The rotary shaft member and the rotor member are pressed and fixed by forming the portions 15 and 17 and tightening the rotor member with screws 16 and 18 attached to the top of the rotary shaft member with both tapered portions in close contact.
As described above, the tapered portions of the rotary shaft members 10 and 11 and the rotor members 13 and 14 are brought into pressure contact with each other so that the rotary shafts of the rotary shaft members 10 and 11 and the rotor members 13 and 14 coincide with each other to perform alignment. .
Japanese Utility Model Publication No. 7-28965

However, in such a conventional method of directly supporting the rotor member on the rotating shaft member, when a material having a high rigidity and a small coefficient of thermal expansion is used as the rotor member and the rotating shaft member, a material having a high rigidity and strength is generally used. Because of the large specific gravity, the rotor was also heavy. If the taper part cannot be machined with high precision in the hollow part for inserting the rotary shaft of the rotor member, and the center of gravity of the rotor does not coincide with the rotary axis due to the difficulty of centering the rotor, Because the rotor is heavy because it receives centrifugal force in the direction of displacement, the rotor precesses, and when the rotor contacts the housing or when a pair of rotors are used, the rotors contact each other and break down. Could occur.

Even if the center of gravity of the rotor can be made substantially coincident with the rotation axis, when a heavy rotor is used, the resonance rotational speed inherent to the rotor provides the performance of the rotor as a pump. There was a problem that it would be lower than the rotational speed.
Therefore, when the rotational frequency is increased above the resonance frequency, the rotational axis of the rotor is greatly displaced from the rotational axis due to the resonance phenomenon, and the rotary rotor and the housing are damaged by contact with the housing and the performance as a pump is deteriorated. There was a possibility that this would occur. Further, in the case of a screw-type vacuum pump or a roots-type vacuum pump having a pair of rotary rotors, there is also a problem that the rotary rotors come into contact with each other and are damaged.

  In the case of a rotor having the same shape, the rotational resonance point shifts to a higher rotational speed as the rotor becomes lighter. Therefore, it is conceivable that the rotating member is formed of a lightweight material. However, lightweight materials generally have a drawback that they are weak in rigidity and easily deform when the housing and the rotating member collide with each other. Further, since the rotor member made of a lightweight material is generally soft when the rotary shaft members 10 and 11 and the rotor members 13 and 14 are pressure-contacted, the rotary member is deformed by a large force applied to the contact portion. Problems can occur.

Further, when the rotor member becomes hotter than the rotating shaft member and the rotor member is thermally expanded more than the rotating shaft member, a gap is formed in the taper contact portion between the rotor member and the rotating shaft member, and the rotor member moves downward. The rotor part and the other rotor member may change, or the backlash between the rotor member and the rotating shaft member may cause contact between the rotor parts or the rotor part and the housing, resulting in damage to the rotor or housing. Or the problem of destruction.
In addition, when the rotating shaft member and the rotor member are made of materials having different thermal expansion coefficients, even if both members have the same temperature rise, due to the difference in the thermal expansion coefficients of the materials constituting the two members, they are joint portions. Since a gap is formed in the tapered portion, the same problem as described above occurs.

  According to the cantilever rotary pump of the present invention, a rotor is rotatably disposed in an exhaust chamber provided in a housing via a bearing provided only at one rotor shaft end, and gas is generated between the housing inner wall and the rotor. In the cantilever rotary pump that forms a transfer chamber and an intake port and an exhaust port communicating with the transfer chamber in the housing, sucks gas from the intake port to the transfer chamber, and discharges gas from the exhaust port, the rotor Is a structure for fixing the inside of the hollow along the rotation axis of the rotor member and the shaft end portion of the rotation shaft member, and the rotation shaft member and the rotor member are integrally fixed via a cylindrical member. . With such a configuration, it is possible to select a material different from that of the rotor member as the material of the cylindrical member. Therefore, the rotor part away from the rotation center is made of a lightweight material, and the cylindrical member close to the rotation center can be made of a material that is heavy but strong in strength. It can be a rotor. Further, in order to increase the accuracy of the teeth on the outer periphery of the rotor with respect to the inner diameter taper, the taper portion of the cylindrical member is processed after press-fitting into the rotor.

According to the cantilever rotary pump of the present invention, the cylindrical member is press-fitted into the hollow of the rotor member, and the press-fitting surfaces of the cylindrical member and the rotor member are parallel to the rotation axis, and the cylindrical member The joint surface between the rotary shaft member and the rotary shaft member is tapered. By adopting such a configuration, it is possible to closely fix the cylindrical member press-fitted to the rotor member by press-fitting and fixing the press-fitting surface parallel to the rotational axis of the cylindrical member and the tapered portion of the rotational shaft. The rotating shaft of the cylindrical member and the rotating shaft of the cylindrical member, and the rotating shaft of the cylindrical member and the rotating shaft of the rotating shaft member can be accurately aligned.
Further, by shrinking or cooling the cylindrical member to the rotor member, even if the coefficient of thermal expansion of the rotor member is larger than that of the cylindrical member, the cylinder member is buffered to some extent and no gap is formed.
Moreover, it is good to provide a stopper part in the axial direction end of a cylinder member or a rotor member so that a cylinder member and a rotor member may not move relatively to a rotating shaft direction.

According to the cantilever rotary pump of the present invention, the cylindrical member is composed of two members, the first cylindrical member is press-fitted into the hollow of the rotor member, and the first cylindrical member and the rotor member The press-fitting surface is parallel to the rotation axis, the joint surface between the first cylindrical member and the second cylindrical member is tapered, and several slits are inserted in the axial direction so that it can expand and contract in the radial direction. The second cylindrical member and the rotary shaft member are inserted by inserting the rotary shaft member into the hollow of the second cylindrical member and joining the first cylindrical member and the second cylindrical member. Can be press-contacted substantially parallel to the rotation axis.
Therefore, it is not necessary to taper the end of the rotating shaft member. Further, the rotation axis of the rotor member and the rotation axis of the cylinder member, and the rotation axis of the cylinder member and the rotation axis of the rotation shaft member can be matched more accurately.
Moreover, it is good to provide a stopper part in a rotating shaft member so that a cylinder member and a rotor member may not move relatively to a rotating shaft direction.

  With this configuration, the cantilevered rotor can be easily pivoted and fixed to the rotating shaft. For example, when used in a vacuum pump that is driven to rotate and used in a semiconductor manufacturing apparatus, the reactive gas may be exhausted by the vacuum pump, and products accumulate in the vacuum pump. Therefore, it becomes necessary to frequently perform maintenance such as disassembly and cleaning in the housing in order to remove the product. At that time, it was necessary to remove the cantilever rotary rotor, and when reassembling, it could not be assembled easily and with good reproducibility in a short time. Therefore, by adopting the configuration as described in claim 1, it is possible to easily and accurately reproducibly align the shaft, and the mounting time of the cantilever rotary rotor can be shortened.

  According to the cantilever rotary pump of the present invention, the material of the cylindrical member is the same material as the rotating shaft member, or between the coefficient of thermal expansion of the material of the rotor member and the material of the rotating shaft member. A material having a thermal expansion coefficient of With such a configuration, it is possible to make it difficult to form a gap between the rotor member and the cylindrical member and between the cylindrical member and the rotating shaft member even if the rotor is thermally expanded. As described above, when the rotor member and the rotor shaft member are fixed to each other through the cylindrical member, and the rotary shaft member and the rotor member are made of materials having different physical characteristics, the physical characteristics of the cylindrical member are intermediate. By using the material, it is possible to suppress adverse effects caused by differences in physical characteristics. If the cylindrical member and the rotating shaft are made of the same material, the rotor member and the rotating shaft expand and contract at the same rate even if the temperature changes. There is no play between the two.

 According to the cantilever rotary pump of the present invention, the diameter of the second cylindrical member outer peripheral portion on the side opposite to the rotating shaft member end side of the second cylindrical member is also small at the cylindrical member end portion. The inner surface of the cylindrical member facing the second taper portion of the cylindrical member is in close contact with the rotary shaft member, and the rotary shaft member is parallel to the rotary shaft member. A third taper member for tightly fixing the second taper portion and the rotary shaft member may be fixed. With such a configuration, the rotation axis can be further easily aligned. As the cylindrical member, a collet or the like that can be expanded and contracted in the radial direction by inserting several slits in the axial direction can be used. By using a collet or the like, it is possible to accurately and accurately center the shaft with a simpler configuration.

  According to the cantilever type rotary pump of the present invention, the material of the rotor member is lighter than the material of the rotating shaft member. By configuring the rotor with such a lightweight material, the resonance rotational speed can be increased to a rotational speed higher than the rotational speed for sufficiently drawing out the performance of the rotary pump. In addition, even if the center of gravity deviates from the rotational axis, if a lightweight rotor is used, even if the rotational axis of the rotor deviates from the designed rotational axis, a large centrifugal force does not work. Contact between the rotor and the housing can be prevented.

  As the material of the rotor member, a light material such as aluminum or magnesium can be used. Aluminum-based and magnesium-based materials are inexpensive and flexible metals, so that there is an advantage that casting, cutting, turning, etc. can be easily performed. Further, the housing can be prevented from contacting the housing and the rotor by using the same material as that of the rotor member and causing the housing and the rotor to thermally expand to the same extent. In addition, since the cylindrical member and the rotating shaft are made of the same material, the rotor member and the rotating shaft expand and contract at the same rate even if the temperature changes. There is no play between the shaft.

  According to the cantilever rotary pump of the present invention, when the rotor member, the rotary shaft member, and the cylindrical member are fixed, the rotor member or the rotary shaft is attached to the tapered portion of the cylindrical member attached to the rotary shaft. The elastic member was arranged so that the taper portion was pressed with a predetermined pressing force. When a normal rotary pump is driven, the temperature of the rotor increases. At this time, when materials having different coefficients of thermal expansion are used for the rotating shaft member and the rotor member, particularly when the coefficient of thermal expansion on the rotor member side is large, a slight gap is formed in the tapered contact portion of the cylindrical member when the rotor expands. As a result, there is a possibility that the rotor member rotates with the backlash generated, and the housing and the rotor or the rotor are brought into contact with each other and damaged. However, by adopting the above configuration, the taper portion is always brought into close contact with the pressing force of the elastic member so that the cylindrical member taper portion and the rotating shaft taper portion do not slip within the entire temperature range rising from room temperature. It is possible to maintain the frictional force necessary to do.

  As the elastic means, a disc spring or the like can be used. By using a disc spring, the elastic member can be easily attached to and detached from the rotating shaft, and the time for maintenance or the like can be shortened.

  According to the cantilever rotary pump of the present invention, the rotor of the cantilever rotary pump is a pair of screw rotors that mesh with each other, and the cantilever rotary pump is used as a vacuum pump. In the case of a screw-type vacuum pump having a pair of rotating rotors, a narrow gap between the housings and the rotating rotor is an essential condition for improving the performance. In the case of a pump, it must be frequently disassembled for maintenance. If the rotary pump of the present invention is installed vertically to form a cantilever rotor, the rotor part is made of lightweight aluminum or magnesium, and the taper fastening part with the shaft is made of a strong iron-based material. Can be easily repeated and high assembly reproduction accuracy can be obtained.

  According to the first aspect of the present invention, a rotor with a small unbalance can be obtained.

  According to the second aspect of the present invention, the rotation shafts of the rotor member, the cylindrical member, and the rotation shaft member can be aligned with high accuracy.

  According to the invention of claim 3 of the present application, it is not necessary to taper the end of the rotating shaft member.

  According to the invention of claim 4 of the present application, it is possible to prevent the gap between the rotor member, the cylindrical member and the rotating shaft member from changing even if the temperature changes.

  According to the invention of claim 5 of the present application, it is possible to further easily and accurately align the rotation axis.

  According to the invention of claim 6 of the present application, the resonance rotational speed can be increased to a rotational speed higher than the rotational speed for sufficiently drawing out the performance of the rotary pump.

  According to the invention of claim 7 of the present application, the elastic member is arranged so as to press the taper portion with a predetermined pressing force. The frictional force necessary to prevent slippage between the member taper portion and the rotating shaft taper portion can be maintained.

  According to the invention of claim 8 of the present application, the maintenance work of the vacuum pump can be performed efficiently.

Embodiments of a vacuum pump according to the present invention will be described below with reference to the drawings. FIG. 5 is a sectional view schematically showing an embodiment of a two-stage screw type vacuum pump according to the present invention.
Here, the first screw-type vacuum pump (first vacuum pump, rotary rotor pump, cantilever rotary pump, pre-stage vacuum pump or booster pump) 1A of FIG. 5 will be described with reference to FIGS. To do.
FIG. 1 is a cross-sectional view schematically showing an embodiment of a first screw vacuum pump (first vacuum pump, rotary rotor pump, cantilever rotary pump, pre-stage vacuum pump or booster pump) 1A. FIG. 2 is a cross-sectional view taken along the line AA in FIG.
As shown in the figure, the first screw-type vacuum pump 1A includes a pair of screw rotors 102 and 103 arranged vertically, and the pair of screw rotors 102 and 103 is housed inside an exhaust chamber housing 171. ing. A housing (exhaust chamber housing) 171 forming the exhaust chamber is constituted by the rotor housing 104, the upper end housing 172, and the bearing housing 173.

  A plurality of working chambers 107 are formed by the pair of screw rotors 102 and 103 and the exhaust chamber housing 171. The working chamber 107 sucks process gas (reaction product gas) from an intake port 153 formed in the rotor housing 104 and the upper end housing 172, and process gas (reaction product gas) as the pair of screw rotors 102 and 103 rotates. Is exhausted from an exhaust port (exhaust port) 154 formed on the side surface of the rotor housing 104.

  The screw rotors 102 and 103 and the exhaust chamber housing 171 are partitioned so that the intake port 153 and the exhaust port (exhaust port) 154 do not always communicate with each other. The exhaust chamber 168 is separated by the screw rotors 102 and 103 on the intake side and the exhaust chamber housing 171. In the position until the intake side is closed, a recess 173 for accommodating a reaction product is provided at the lower end of the intake port 153 formed in the rotor housing 104. Further, a baffle plate 174 is arranged at the intake port 153 above the screw rotors 102 and 103 so that a lump of reaction products does not fall directly into the exhaust chamber 168.

  Between the screw rotors 102 and 103 and the exhaust chamber housing 171, there is a minute gap including the end surfaces of the screw rotors 102 and 103, but the second screw-type vacuum pump that is disposed on the atmosphere side and requires an air sealing function. The gap may be larger than that.

  Further, the second screw vacuum pump (the latter stage vacuum pump or the main stage pump) has a large power for exhausting to the atmosphere by being volume-compressed and exhausted by the first screw type vacuum pump (first stage vacuum pump or booster pump) 1A. Tap pump) 1B can be reduced in size and energy is saved.

  The screw rotor 102 includes a rotor member 156 and a rotating shaft member 105. The rotor member 156 is made of an aluminum material, and the rotary shaft member 105 is made of an iron material. The rotor member 156 is a hollow rotor, and a cylindrical member 157 made of an iron-based material is shrink-fitted or cold-fitted in the hollow portion. In this way, the cylindrical member 157 made of an iron-based material is shrink-fitted or cold-fitted to the rotor member 156 made of an aluminum-based material, so that the aluminum-based material is more iron-based when the temperature rises. Even if the thermal expansion is greater, the compression of the iron-based material and the expansion of the aluminum-based material due to shrink fitting or cold fitting are buffered, and a gap is less likely to be generated between the rotor member 156 and the cylindrical member 157. Further, the joint surface between the rotor member 156 and the cylindrical member 157 has a cylindrical shape so that the rotational axes of both members can be easily aligned. A step portion 166 is provided at the lower end of the cylindrical member 157 so that the relative position in the axial direction of the rotor member 156 does not change. Further, a taper that becomes narrower toward the upper part is provided on the inner periphery of the cylindrical member 157, and a taper having the same shape as the taper of the cylindrical member 157 that becomes thinner toward the end also at the upper end of the rotary shaft member 105 is provided. It is. Then, the rotating shafts of the rotor member 156 and the cylindrical member 157 are made to coincide with each other by bringing the tapered portions of the cylindrical member 157 and the rotating shaft member 105 into pressure contact with each other. The cylindrical member 157 and the rotating shaft member 105 are the same iron-based material, and there is almost no difference in the amount of thermal expansion due to a temperature change. The cylindrical member 157 and the rotating shaft member 105 are brought into pressure contact with each other by disposing a disc spring 158 between the upper surface of the cylindrical member 157 and a bolt 159 fastened to the upper end of the rotating shaft member 105. A lid 160 is fastened to the upper end portion of the screw rotor 102 so that reactive organisms do not accumulate in the hollow portion of the rotor member 156.

  Similarly, the screw rotor 103 includes a rotor member 161 and a rotating shaft member 108. The rotor member 161 is made of an aluminum material, and the rotary shaft member 108 is made of an iron material. The rotor member 161 is a hollow rotor, and a cylindrical member 162 made of an iron-based material is shrink-fitted or cold-fitted in the hollow portion. In this way, the cylindrical member 162 made of an iron-based material is shrink-fitted or cold-fitted to the rotor member 161 made of an aluminum-based material, so that when the temperature rises, the aluminum-based material is more iron-based material. Even if the thermal expansion is greater than that, the compression of the iron-based material and the expansion of the aluminum-based material due to shrink fitting or cold fitting are buffered, and it is possible to make it difficult to form a gap between the rotor member 161 and the cylindrical member 162. Further, the joint surface between the rotor member 161 and the cylindrical member 162 is formed in a cylindrical shape so that the rotation axes of both members can be easily aligned. A step portion 167 is provided at the lower end of the cylindrical member 162 so that the relative position in the axial direction with the rotor member 161 does not change. Further, a taper that narrows toward the upper part is provided on the inner periphery of the cylindrical member 162, and further, a taper having the same shape as the taper of the cylindrical member 162 that becomes thinner toward the end part is also provided at the upper end of the rotary shaft member 108. is there. Then, the rotating portions of the rotor member 161 and the cylindrical member 162 are made to coincide with each other by pressing the taper portions of the cylindrical member 162 and the rotating shaft member 108 together, and further, the rotating shaft of the rotating shaft member 108 is also made to coincide. The cylindrical member 162 and the rotating shaft member 108 are the same iron-based material, and there is almost no difference in the amount of thermal expansion due to temperature change. The cylindrical member 162 and the rotary shaft member 108 are brought into pressure-contact with each other by disposing a disc spring 163 between the upper surface of the cylindrical member 162 and a bolt 164 fastened to the upper end of the rotary shaft member 108. A lid 165 is fastened to the upper end portion of the screw rotor 103 so that reactive organisms do not accumulate in the hollow portion of the rotor member 161.

  The screw rotors 102 and 103 can be rotated at a high speed by increasing the resonance frequency by providing a lightweight aluminum-based material and a hollow portion like the screw rotors 102 and 103 to make the screw rotors 102 and 103 as light as possible. . As a result, the first vacuum pump (previous vacuum pump or booster pump) can be reduced in size and the sealing performance can be improved, so that the first vacuum pump (previous vacuum pump or booster pump) with good exhaust efficiency can be configured. .

  In the screw rotor 102, a rotary shaft portion 105 of the rotor is rotatably supported in a rotor housing 104 by bearings 106 and 101 provided at an upper portion below the rotary shaft portion 105 and a bearing 123 provided at a lower portion. . In order to prevent the process gas (reaction product gas) in the exhaust chamber from leaking to the bearing side and accumulating on the bearing or contaminating the lubricating oil between the bearing 106 and the exhaust chamber 168, the lubricating oil on the bearing side 106 is further exhausted. A shaft seal 169 is provided so as not to leak to the chamber 168 side. The bearings 106, 101, and 123 are pressurized by a disc spring (not shown).

  Similarly, in the screw rotor 103, the rotating shaft portion 108 of the rotor can be rotated in the rotor housing 104 by bearings 109 and 110 provided at the upper portion below the rotating shaft portion 108 and a bearing 124 provided at the lower portion. It is supported. In order to prevent process gas (reaction product gas) in the exhaust chamber from leaking to the bearing side and accumulating on the bearing or contaminating the lubricating oil between the bearing 109 and the exhaust chamber 168, the lubricating oil on the bearing side 109 is further exhausted. A shaft seal 170 is provided so as not to leak to the chamber 168 side. The bearings 109, 110, and 124 are pressurized by a disc spring (not shown) or the like.

  The outer rings of the bearings 106 and 101 are press-fixed to the inner periphery of a cylindrical bearing support member 175 made of an iron-based material, and the outer peripheral portion of the bearing support member 175 is press-contacted to a bearing housing 175 made of an aluminum-based material. It is fixed. A projecting portion 180 is formed at the lower end of the bearing support member 175 in the radial direction of the rotary shaft so as to be easily positioned in the axial direction with respect to the outer ring of the bearing and the bearing housing 175. Similarly, the outer rings of the bearings 109 and 110 are pressure-fixed to a bearing support member 177 made of an iron-based material, and the bearing support member 177 is pressure-fixed to a bearing housing 176 made of an aluminum-based material. At the lower end of the bearing support member 177, a protruding portion 181 is formed in the radial direction of the rotary shaft so as to be easily positioned in the axial direction with respect to the outer ring of the bearing and the bearing housing 176. In this way, it is fixed to the bearing housing 176 made of an aluminum-based material having a different thermal expansion coefficient through the bearing support members 175 and 177 having substantially the same thermal expansion coefficient as the outer rings of the bearings 106, 101, 109, and 110. By doing so, it is possible to prevent a gap from being changed between the outer rings of the bearings 106, 101, 109, and 110 and the bearing support members 175 and 177.

  Further, the bearing housing 176 is formed with a hollow portion 182 for thermally insulating the bearings 106, 101, 109, 110 and the exhaust chamber 168. Thus, heat between the exhaust chamber 168 and the bearings 106, 101, 109, 110 is prevented so that heat such as compression heat of the exhaust gas generated in the exhaust chamber 168 is not transmitted to the bearings 106, 101, 109, 110. Providing a space in the conduction path makes it difficult for heat to be transferred to the bearings 106, 101, 109, and 110, and prevents breakage due to the high temperature of the bearings 106, 101, 109, and 110. By providing the hollow portion 182 around the bearings 106, 101, 109, and 110, a heat conduction path through which heat is transmitted to the bearings 106, 101, 109, and 110 through the bearing housing 176 can be lengthened, so that a more heat insulating effect can be obtained. improves. Further, when a reaction product gas that becomes solid at low temperature flows, the vacuum pump is operated by setting the flow path of the reaction product gas (intake port 153 → exhaust chamber 168 → exhaust port 154) to a high temperature so that the reaction product does not accumulate. However, there is an effect of preventing the heat around the exhaust chamber 168 maintained at a high temperature by the hollow portion 182 from being transmitted to the bearings 106, 101, 109, and 110.

  The rotor housing 104, the upper end housing 172 and the bearing housing 173 constituting the exhaust chamber housing 171 are made of the same aluminum material as the rotor member 161 made of an aluminum material, and have the same thermal expansion coefficient. This prevents the gap between the screw rotors 102 and 103 and the exhaust chamber housing 171 from changing with temperature. Further, since the exhaust chamber housing 171 is made of an aluminum-based material, the heat conductivity is good and the heat generated near the exhaust port 153 can be easily transferred to the intake port 154 side, and the temperature of the exhaust chamber 168 can be made uniform.

  A heat transfer plate 183 made of an aluminum material for controlling the temperature in the exhaust chamber 168 is in close contact with the periphery of the rotor housing 104. A passage 184 for flowing a cooling medium (water or the like) or a heating medium (high-temperature and high-pressure steam or the like) is formed in the heat transfer plate, and heating and cooling are performed with these media. For example, when exhausting a reaction product gas that solidifies at a high temperature such as tungsten, the exhaust chamber needs to be maintained at a low temperature, and cooling water is supplied to the path 184.

A cooling plate 185 made of an aluminum-based material is disposed at a position at the lower end of the bearing housing 176 and in contact with a heat conduction path through which heat is transferred to the bearings 106, 101, 109, 110 via the bearing housing 176. When the bearings 106, 101, 109, and 110 cannot be sufficiently maintained at a low temperature only by the hollow portion 182, the amount of heat conducted to the bearings 106, 101, 109, and 110 can be reduced by arranging the cooling plate 185. Therefore, the temperature rise of the bearings 106, 101, 109, 110 can be suppressed.
The cooling plate 185 is provided with a cooling path 186 for allowing a medium such as cooling water to flow, thereby further improving the cooling efficiency.

  Further, the cooling plate 185 is in contact with the motor housing 187, and the motor 113 can be cooled. Further, a second cooling plate 188 is in close contact with the outer periphery of the motor housing 187, and the motor 113 is also cooled by the second cooling plate 188. Further, the second cooling plate 188 is formed with a cooling path 189 for flowing a medium such as cooling water, thereby further improving the cooling efficiency.

  A timing gear 111 is provided at the lower end portion of the rotating shaft portion 105, and a timing gear 112 is provided at the lower end portion of the rotating shaft portion 108. When the timing gears 111 and 112 mesh with each other, the screw rotors 102 and 103 are engaged. Are configured to rotate in a non-contact manner synchronously.

  A permanent magnet type rotor 150 of the motor 113 is fixed between the bearing 110 and the timing gear 112 of the rotating shaft portion 108, and canned by a can 151. When the vacuum pump is driven and the inside of the exhaust chamber 168 is evacuated, the motor 113 side is also evacuated, so the can 151 prevents the rotor 150 side from being separated from the atmosphere, thereby preventing atmospheric leakage to the exhaust chamber 168. . Further, when the pressure of the exhaust port 153 becomes higher than the atmospheric pressure at the start of operation, the process gas in the exhaust chamber 168 may leak to the motor 113 side. In this case, the process gas can be prevented from leaking to the atmosphere due to the motor being canned. An electromagnet stator 152 of the motor 113 is fixed outside the can 151, and the rotational speed of the screw rotor 103 is controlled by an inverter. Furthermore, the screw rotors 102 and 103 are configured to rotate in a non-contact manner synchronously by transmitting the rotational motion to the screw rotor 102 via the timing gears 111 and 112.

  The timing gears 111 and 112 are housed in an oil chamber 127 in which lubricating oil 126 partitioned by an oil housing 125 is stored. The timing gears 111 and 112 are configured to be supplied with lubricating oil by a lubricating oil supply means (not shown). Further, by changing the axial thickness of the timing gears 111 and 112 and aligning the bottom surfaces in the axial direction, the lubricating oil blown from the timing gear 111 to the timing gear 112 due to the centrifugal force of rotation is exchanged with the timing gear 112. Stopped at the stepped portion, the meshing portion with the timing gears 111 and 112 is lubricated.

Next, the second screw type vacuum pump (rotary rotor type pump, cantilever type rotary pump, rear vacuum pump or main pump) 1B of FIG. 5 will be described with reference to FIGS.
FIG. 3 is a sectional view schematically showing an embodiment of the second screw type vacuum pump (rotary rotor type pump, cantilever type rotary pump, rear vacuum pump or main pump) 1B. 4 is a cross-sectional view taken along the line BB in FIG.
As shown in the figure, the screw type vacuum pump 1 B includes a pair of screw rotors 202 and 203 arranged vertically, and the pair of screw rotors 202 and 203 are housed inside an exhaust chamber housing 271. The exhaust chamber housing 271 includes a rotor housing 204, an upper end housing 272, and a bearing housing 276.

  A plurality of working chambers 207 are formed by the pair of screw rotors 202 and 203 and the exhaust chamber housing 271. The plurality of working chambers 207 suck process gas (reaction product gas) from an intake port 253 formed in the upper end housing 272 and transfer the process gas (reaction product gas) as the pair of screw rotors 202 and 203 rotate. Then, the air is exhausted from an exhaust port (exhaust port) 254 formed on the side surface of the lower end of the rotor housing 204.

  At the upper end of the upper end housing 272, that is, the cantilevered screw rotors 202, 203 having the structure described below, an exhaust port 154 of the first screw type vacuum pump 1A and an intake port 253 of the second screw type vacuum pump 1B are provided. A pulsation prevention space 290 for buffering the pulsation is formed when the intermediate pressure between the two pulsates. For example, when the atmospheric pressure is suddenly exhausted from the vacuum state as an extreme case, the maximum pressure of the pulsation becomes equal to or higher than the atmospheric pressure (in some cases, more than several times the atmospheric pressure), and the exhaust port 154 of the first screw type vacuum pump 1A. And pulsation between the suction port 253 of the second screw type vacuum pump 1B and process gas leaks to the bearing 109 side of the first screw type vacuum pump 1A having a low pressure, causing a failure. Further, when a pulsation with a large pressure change occurs in the intermediate pressure, in the case of cantilever screw rotors such as the first screw vacuum pump 1A and the second screw vacuum pump 1B, the screw rotor is biased in the bending direction. A force is generated, causing contact between the screw rotor or between the screw rotor and the housing, causing damage. In particular, the first screw-type vacuum pump has a plurality of working chambers formed in parallel, for example, a pair of screw rotors such as three, four, four, and six, and is exhausted by volume compression. The pressure of each working chamber at the exhaust end face is different, and the force in the direction of bending with respect to the screw rotor increases. The second screw-type vacuum pump has a structure in which both screw rotors are single and exhausted without volume compression. Since the shaft diameter is smaller than the screw rotor of the first screw-type vacuum pump, Compared with the vacuum pump, the force in the direction of bending with respect to the screw rotor is not so great.

  A trap member 291 is disposed in the pulsation prevention space 290 formed in the upper end housing 272 so as to partition the intake port 253 and the exhaust chamber 268 so that reaction products do not enter the exhaust chamber 268. The trap member 291 has a hollow structure that tapers from the lower end to the upper end, and is configured such that reaction products accumulate in a groove 292 formed between the upper end housing 272 and the trap member 291. By configuring the upper end housing 272 as a side housing in which the upper surface flange and the air inlet 253 are formed, the reaction product accumulated in the groove portion 292 can be cleaned only by removing the upper surface flange.

  A small gap is formed between the screw rotors 202 and 203 and at least the rotor housing 204.

  The screw rotor 202 includes a rotor member 256 and a rotating shaft member 205. The rotor member 256 and the rotating shaft member 205 are made of an iron-based material. The rotor member 256 is a hollow rotor, and a taper that narrows toward the upper part is provided on the inner periphery of the rotor member 256, and further, the taper of the rotor member 256 that becomes narrower toward the upper end of the rotary shaft member 205. A taper of the same shape is provided. Then, the rotating shafts of the rotor member 156 and the rotating shaft member 205 can be easily matched by press-contacting the tapered portions of the rotor member 256 and the rotating shaft member 205 with each other. The rotor member 256 and the rotating shaft member 205 are the same iron-based material, and there is almost no difference in the amount of thermal expansion due to temperature change. The rotor member 256 and the rotary shaft member 205 are pressure-contacted by a tapered portion by disposing a disc spring 258 between the hollow inner upper surface of the rotor member 256 and the bolt 259 fastened to the upper end of the rotary shaft member 205. . A lid 260 is fastened to the upper end portion of the screw rotor 202 so that reactive organisms do not accumulate in the hollow portion of the rotor member 256.

  Similarly, the screw rotor 203 includes a rotor member 261 and a rotating shaft member 208. The rotor member 261 and the rotating shaft member 208 are made of an iron-based material. The rotor member 261 is a hollow rotor, and is provided with a taper that becomes narrower toward the upper part of the inner periphery of the rotor member 261. Further, the upper end of the rotary shaft member 208 becomes thinner toward the end, and the taper of the rotor member 261 is reduced. A taper of the same shape is provided. Then, the rotating shafts of the rotor member 261 and the rotating shaft member 208 can be easily matched by pressing the tapered portions of the rotor member 261 and the rotating shaft member 208 together. The rotor member 261 and the rotating shaft member 208 are the same iron-based material, and there is almost no difference in the amount of thermal expansion due to temperature change. The rotor member 261 and the rotary shaft member 208 are pressure-contacted by a tapered portion by disposing a disc spring 264 between the hollow inner upper surface of the rotor member 261 and the bolt 264 fastened to the upper end of the rotary shaft member 208. . A lid 265 is fastened to the upper end portion of the screw rotor 203 so that reactive organisms do not accumulate in the hollow portion of the rotor member 261.

In the first screw-type vacuum pump, in order to obtain the exhaust capacity, the screw rotor becomes large, and the weight of the rotating part becomes heavy. However, the exhaust chamber 168 during operation is in the vicinity of the molecular flow region, and the gap between the screw rotor and between the screw rotor and the rotor casing can be widened, so that even a material having a large thermal expansion coefficient can be used. Therefore, the screw rotor of the first screw type vacuum pump is optimally made of an aluminum-based material that has a large thermal expansion coefficient but is lightweight.
On the other hand, the second screw type vacuum pump has a smaller exhaust capacity than the first screw type vacuum pump, so the screw rotor part is small, but a sealing function is required to suppress the backflow of the atmosphere. It is necessary to narrow the gap between the screw rotor and the rotor casing. Therefore, the screw rotor of the second screw-type vacuum pump is optimally an iron-based material having a high density but a low thermal expansion coefficient.

  In the screw rotor 202, the rotary shaft portion 205 of the rotor is rotatably supported in the rotor housing 204 by bearings 206 and 201 provided in the upper portion below the rotary shaft portion 205 and a bearing 223 provided in the lower portion. . In order to prevent the process gas (reaction product gas) in the exhaust chamber from leaking to the bearing side and accumulating on the bearing between the bearing 206 and the exhaust chamber 268, the lubricating oil on the bearing side 206 is further removed. A shaft seal 269 is provided so as not to leak to the exhaust chamber 268 side. The bearings 206, 201, and 223 are pressurized by a disc spring (not shown).

  Similarly, in the screw rotor 203, the rotary shaft portion 208 of the rotor can be freely rotated in the rotor housing 204 by the bearings 209 and 210 provided in the upper portion below the rotary shaft portion 208 and the bearing 224 provided in the lower portion. It is supported. In order to prevent the process gas (reaction product gas) in the exhaust chamber from leaking to the bearing side and accumulating on the bearing between the bearing 209 and the exhaust chamber 268, the lubricating oil on the bearing side 209 is further removed. A shaft seal 270 is provided so as not to leak to the exhaust chamber 268 side. The bearings 206, 201, and 223 are pressurized by a disc spring (not shown) or the like.

The outer rings of the bearings 206 and 201 are fixed to the inner periphery of a cylindrical bearing support member 275 made of an iron-based material, and the outer peripheral portion of the bearing support member 275 is pressed against a bearing housing 276 made of an iron-based material. It is fixed. At the lower end of the bearing support member 275, a protrusion 280 is formed in the radial direction of the rotary shaft so as to be easily positioned in the axial direction with respect to the outer ring of the bearing and the bearing housing 276. Similarly, the outer rings of the bearings 209 and 210 are press-fixed to a bearing support member 277 made of an iron-based material, and the bearing support member 277 is press-fixed to a bearing housing 276 made of an iron-based material. At the lower end of the bearing support member 277, a protruding portion 281 is formed in the radial direction of the rotary shaft so as to be easily positioned with respect to the outer ring of the bearing and the bearing housing 276 in the rotary shaft direction. The bearing support members 275 and 277 are disposed so as to support the bearing in the empty portion 282 described later.
Thus, by fixing the outer ring of the bearings 206, 207, 209, 210 to the bearing housing 276 via the bearing support members 275, 277, the hollow portion 282 and the bearings 206, 207, 209, 210 are connected in series in the axial direction. Without the arrangement, the axial length of the vacuum pump can be shortened.

  Further, the bearing housing 276 is formed with a hollow portion 282 for thermally insulating the bearings 206, 207, 209, 210 and the exhaust chamber 268. Thus, heat between the exhaust chamber 268 and the bearings 206, 207, 209, 210 is prevented so that heat such as compression heat of the exhaust gas generated in the exhaust chamber 268 is not transmitted to the bearings 206, 207, 209, 210. By providing a space in the conduction path, it becomes difficult for heat to be transferred to the bearings 206, 207, 209, and 210, and breakage due to a high temperature of the bearings 206, 207, 209, and 210 can be prevented. By providing the hollow portion 282 around the bearings 206, 207, 209, and 210, a heat conduction path through which heat is transmitted to the bearings 206, 207, 209, and 210 via the bearing housing 176 can be lengthened, so that a more heat insulating effect can be obtained. improves. Further, when the reaction product gas is exhausted, it is necessary to operate the vacuum pump with a high temperature in the path (intake port 253 → exhaust chamber 268 → exhaust port 254) through which the reaction product gas flows so that the reaction product does not accumulate. However, there is an effect that heat around the exhaust chamber 268 maintained at a high temperature by the hollow portion 282 is prevented from being transmitted to the bearings 206, 207, 209, and 210.

  The rotor housing 204, the upper end housing 272, and the bearing housing 276 constituting the exhaust chamber housing 271 are made of the same iron-based material as the rotor member 161 made of an iron-based material, and have the same thermal expansion coefficient. Thus, the gap between the screw rotors 202 and 203 and the exhaust chamber housing 271 is prevented from changing with temperature.

  A heat transfer plate 283 made of an aluminum material for controlling the temperature in the exhaust chamber 268 is in close contact with the periphery of the rotor housing 204. A passage 284 for flowing a cooling medium (water or the like) or a heating medium (high-temperature high-pressure steam or the like) is formed in the heat transfer plate 283, and heating / cooling is performed with these media. For example, when exhausting a reaction product gas that is solidified at a high temperature such as tungsten, the exhaust chamber needs to be maintained at a low temperature, and cooling water is supplied to the path 284. In this way, the heat transfer plate 283 made of an aluminum material having a thermal conductivity better than that of an iron material is brought into close contact with the rotor housing 204 to equalize the temperature of the rotor housing 204.

A cooling plate 285 made of an aluminum-based material is disposed at a position at the lower end of the bearing housing 276 and in contact with a heat conduction path through which heat is transferred to the bearings 206, 207, 209, and 210 via the bearing housing 276. When the bearings 206, 207, 209, and 210 cannot be sufficiently maintained at a low temperature only by the hollow portion 282, the cooling plate 285 is disposed to reduce the amount of heat conducted to the bearings 206, 207, 209, and 210. Therefore, the temperature rise of the bearings 206, 207, 209, and 210 can be suppressed.
The cooling plate 285 is provided with a cooling path 286 for allowing a medium such as cooling water to flow, thereby further improving the cooling efficiency.

  Further, the cooling plate 285 is in contact with the motor housing 287, and the motor 213 can be cooled. Further, a second cooling plate 288 is in close contact with the outer periphery of the motor housing 287, and the motor 213 is also cooled by the second cooling plate 288. The second cooling plate 288 is provided with a cooling path 289 for allowing a medium such as cooling water to flow, thereby further improving the cooling efficiency.

  A timing gear 211 is provided at the lower end portion of the rotating shaft portion 205, and a timing gear 212 is provided at the lower end portion of the rotating shaft portion 208. When the timing gears 211 and 212 mesh with each other, the screw rotors 202 and 203 are engaged. Are configured to rotate in a non-contact manner synchronously.

  A permanent magnet type rotor 250 of the motor 213 is fixed between the bearing 210 of the rotating shaft portion 208 and the timing gear 212, and canned by a can 251. When the exhaust port 254 side of the second screw type vacuum pump is clogged, the pressure in the vicinity of the exhaust port 254 may become higher than the atmospheric pressure, and the process gas in the exhaust chamber 268 leaks to the motor 213 side. In this case, since the motor 213 is canned, the process gas can be prevented from leaking to the atmosphere. An electromagnet stator 252 of the motor 213 is fixed outside the can 251 and the rotational speed of the screw rotor 203 is controlled by an inverter. Furthermore, the screw rotors 202 and 203 are configured to rotate in a non-contact manner synchronously by transmitting the rotational motion to the screw rotor 202 via the timing gears 211 and 212.

  The timing gears 211 and 212 are accommodated in an oil chamber 227 in which lubricating oil 226 partitioned by an oil housing 225 is stored. The timing gears 211 and 212 are configured to be supplied with lubricating oil by a lubricating oil supply means (not shown). Furthermore, by changing the axial thickness of the timing gears 211 and 212 and aligning the bottom surfaces in the axial direction, the lubricating oil blown from the timing gear 211 to the timing gear 212 by the centrifugal force of rotation is exchanged with the timing gear 212. Stopped by the stepped portion, the meshing portion with the timing gears 211 and 212 is lubricated.

  Since some reaction product gases tend to solidify when the pressure increases, an inert gas is injected into the exhaust chamber on the side of the rotor housing 204 of the second screw vacuum pump 1B disposed on the atmosphere side. An inert gas injection path 295 is provided for diluting the reaction product gas to make it difficult to produce a reaction product.

  Finally, referring to FIG. 5, the exhaust port 154 of the first screw type vacuum pump 1A and the intake port 253 of the second screw type vacuum pump 1B are connected in series and the vertical two-stage screw type vacuum pump 300 is connected. The configuration will be described.

As shown in FIG. 5, the exhaust path formed by the exhaust port 154 of the first screw-type vacuum pump 1A, the intake port 253 of the second screw-type vacuum pump 1B, and the intermediate pipe 301 is horizontal. By disposing, the exhaust port 154 of the first screw type vacuum pump 1A and the intake port 253 of the second screw type vacuum pump 1B can be connected with almost no decrease in conductance.
Further, the exhaust port 154 of the first screw-type vacuum pump 1A and the intake port 253 of the second screw-type vacuum pump 1B may be connected without using the intermediate pipe 301.

  When repairing or maintaining the screw rotor part, the fastening between the bearing housing and the rotor housing of each of the first screw type vacuum pump and the second screw type vacuum pump is released, and the upper part of the rotor housing together with the rotor housing. By removing the upper end housing and the like disposed on the screw rotor portion, the screw rotor portion can be easily exposed to the operator, so that workability is improved and assembly is facilitated.

  Hereinafter, a second embodiment of the rotary pump according to the present invention will be described with reference to FIG. FIG. 6 shows an embodiment in which the present invention is applied to a cantilever screw type vacuum pump.

  A housing for housing the screw rotor is formed by sandwiching the hollow member 305 between the flange 302 formed with the intake port 301 and the flange 304 formed with the exhaust port 103. In this housing, there are screw rotors 306 and 307 housed in parallel so as to mesh with each other in a non-contact meshing state with a predetermined clearance (a minute gap). The screw rotor 306 is fixed in the housing with bearings 308 and 309, and the screw rotor 307 is fixed with bearings 310 and 311. The exhaust chamber 312 kept in a vacuum and the space lubricated with oil such as a bearing and a gear are partitioned by seal members 313 and 314 for sealing the shaft hole. A rotating shaft of a motor 312 for rotating the screw rotor 306 is attached to one end of the rotating shaft of the rotor 306 via a connection member 315, and the rotation of the screw rotor 306 is integrated with the screw rotors 306 and 307. The screw rotor 307 is synchronously rotated in the reverse direction by the synchronous gears 313 and 314 attached to the motor.

  The screw rotor 306 and the screw rotor 307 have a predetermined clearance with respect to the inner wall surface of the housing. Between the housing 303 and the screw rotors 306 and 307, the meshing portions of the screw rotors 306 and 307 are provided. A plurality of spiral working chambers that are partitioned from each other and transferred in the axial direction of the rotating shaft by rotation of the screw rotors 304 and 305 are formed.

  Next, a method for fixing the screw rotors 306 and 307 to the rotating shafts 316 and 317 will be described. The rotating shafts 316 and 317 are cylindrical members that are tapered such that the outer diameter decreases toward both ends, and that can be expanded and contracted in the radial direction by inserting several slits in the axial direction. The cylindrical portions 316 and 317 for fixing the rotor have the tapered portions 318 and 319 fixed at close contact with the rings 320 and 321 having the same inner diameter taper angle. As a result, the rotor fixing cylindrical members 316 and 317 can be accurately aligned. The rings 320 and 321 are fixed to the protrusions 322 and 323 of the rotating shaft whose lower ends have a diameter larger than the inner diameter. Reference numerals 306 and 307 denote screw rotors made of an aluminum-based light metal, which are integrally formed with in-rotor cylindrical members 326 and 327 made of a highly rigid metal such as iron or stainless steel. The inner diameter portions of the rotor inner cylindrical members 326 and 327 are formed with the same taper as the taper angles of the taper portions 328 and 329 at the upper end portions of the rotor fixing cylindrical members 316 and 317. The screw rotor is inserted into the rotating shafts 314 and 315 by joining the tapered portions of the rotor inner cylindrical members 326 and 327 and the tapered portions 328 and 329 at the upper end portions of the cylindrical cylindrical members 316 and 317.

  By adopting such a configuration, the shaft can be easily aligned and the rotating shaft and the rotating rotor can be fixed in a short time. Therefore, even if the screw type vacuum pump of this embodiment is used for exhausting reaction product gas in the semiconductor manufacturing apparatus, and the reaction product accumulates in the vacuum pump and is frequently subjected to disassembly maintenance, it can be easily disassembled and assembled. And maintenance time can be shortened.

  Further, by making the screw rotors 306 and 307 hollow and making the material lighter, even when the rotational center of gravity deviates from the rotational axis, the rotational speed is sufficient to bring out the performance of the vacuum pump. Can be increased to a higher rotational speed. Therefore, even if the rotational speed of the screw rotors 306 and 307 is increased to the rotational speed for stable performance, resonance does not occur and the housing and the screw rotors 306 and 307 or the screw rotor 306 and the screw rotor 307 This can prevent the housing or the screw rotors 306 and 307 from being broken.

  Further, by making the screw rotors 306 and 307 hollow and making the material lighter, even when the rotational center of gravity deviates from the rotational axis, the rotational speed is sufficient to bring out the performance of the vacuum pump. Can be increased to a higher rotational speed. Therefore, even if the rotational speed of the screw rotors 306 and 307 is increased to the rotational speed for stable performance, resonance does not occur and the housing and the screw rotors 306 and 307 or the screw rotor 306 and the screw rotor 307 This can prevent the housing or the screw rotors 306 and 307 from being broken.

  Further, by using the rotor inner cylindrical members 326 and 327 made of a highly rigid metal such as iron or stainless steel, the rotor inner cylindrical members 326 and 327 having high rigidity can be obtained even if a light material is used for the screw rotors 306 and 307. Therefore, the deformation of the screw rotors 306 and 307 can be suppressed.

  The screw rotors 306 and 307 are fixed to the rotating shaft by lock nuts 332 and 333 via disc springs 330 and 331 fitted in the hollows of the screw rotors 306 and 307.

  With this configuration, even if the rotary shafts 314 and 315 and the screw rotors 304 and 305 are thermally expanded due to a temperature rise, the screw rotor is formed by the tapered portions of the cylindrical members 326 and 327 and the cylindrical member 316 and 317. In the screw rotor, the tapered portions of the cylindrical members 326 and 327 and the cylindrical member 316 and 317 slide in the axial direction so that the rotary rotor is deformed so that there is no gap between the tapered portions 328 and 329 at the upper end of the rotating member. This can be prevented.

  FIG. 7 illustrates one method of integrally forming screw rotors 304 and 305 made of aluminum-based light metal and rotor inner cylindrical members 326 and 327 made of a rigid metal such as iron or stainless steel. . FIG. 2 is a cross-sectional view of the rotor inner cylindrical members 326 and 327 as viewed in the direction perpendicular to the rotation axis. The cylindrical members 326 and 327 have one or a plurality of projecting portions 440 on the outer peripheral portion, and screw rotors made of aluminum-based light metal by fixing the in-rotor cylindrical members 326 and 327 to a mold and pouring aluminum into the mold. 306, 307 and rotor inner cylindrical members 326, 327 made of a rigid metal such as iron or stainless steel are integrally formed.

  It can be applied to a rotary rotor type fluid pump, a cantilever type rotary fluid pump, a rotary rotor type vacuum pump, a cantilever type rotary vacuum pump, and the like. In particular, it can be applied to a cantilever screw vacuum pump for exhausting process gas used in semiconductor manufacturing processes, and in particular, to a multi-stage cantilever screw vacuum pump in which a plurality of cantilever screw vacuum pumps are connected in series. .

It is sectional drawing which shows typically embodiment of the 1st screw type vacuum pump of the two-stage screw type vacuum pump which concerns on this invention. It is AA sectional drawing of FIG. It is sectional drawing which shows typically embodiment of the 2nd screw type vacuum pump of the two-stage screw type vacuum pump which concerns on this invention. It is BB sectional drawing of FIG. It is sectional drawing which shows typically embodiment of the two-stage screw type vacuum pump which concerns on this invention. It is sectional drawing of the 2nd Example of the screw type vacuum pump which concerns on this invention. It is an axial vertical cross section of the fixing part to the rotor of the taper component of this invention. It is explanatory drawing which showed the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A 1st screw type vacuum pump 102,103 Screw rotor 104 Rotor housing 105 Rotary shaft member 101,106,109,110,123,124 Bearing 107 A working chamber is formed 113 Motor 111,112 Timing gear 125 Oil housing 126 Lubricating oil 150 Rotor 151 Can 152 Stator 153 Intake port 154 Discharge port (exhaust port)
156 Rotor member 157 Cylinder member 166 Stepped portions 158 and 163 Disc springs 159 and 164 Bolt 160 and 165 Lid 168 Exhaust chamber 169 and 170 Shaft seal 171 Exhaust chamber housing 172 Upper end housing 173 Bearing housing 174 Baffle plates 175 and 177 Bearing support member 182 Hollow part 183 Heat transfer plate 184 Path 185 Cooling plate 186, 189 Cooling path 188 Second cooling plate

Claims (8)

  A rotor is rotatably disposed in an exhaust chamber provided in the housing via a bearing provided only at one rotor shaft end, and a gas transfer chamber is formed by the inner wall of the housing and the rotor and communicated with the transfer chamber. In the cantilever rotary pump that forms a suction port and an exhaust port in the housing, sucks gas from the suction port to the transfer chamber, and discharges gas from the exhaust port, the rotor is formed in a hollow space along the rotation axis of the rotor member. A cantilever rotary pump having a structure for fixing a shaft end portion of a rotary shaft member, wherein the rotary shaft member and the rotor member are integrally fixed via a cylindrical member.   The cylinder member is press-fitted into the hollow of the rotor member, a press-fitting surface between the cylinder member and the rotor member is parallel to the rotation axis, and a joint surface between the cylinder member and the rotation shaft member is tapered. The cantilever rotary pump according to claim 1, wherein:   The cylindrical member is composed of two members, the first cylindrical member is press-fitted into the hollow of the rotor member, and the press-fitting surfaces of the first cylindrical member and the rotor member are parallel to the rotation axis, The joining surface of the first cylindrical member and the second cylindrical member is tapered, and the rotating shaft member is inserted into the hollow of the second cylindrical member, and the first cylindrical member and the second cylindrical member are inserted. 2. The cantilever according to claim 1, wherein when the cylindrical member is joined, the joint surface between the second cylindrical member and the rotary shaft member is in pressure contact with the rotary shaft substantially in parallel. Rotary pump.   As the material of the cylindrical member, the same material as the rotating shaft member or a material having a thermal expansion coefficient between the material of the rotor member and the material of the rotating shaft member is used. The cantilever rotary pump according to any one of claims 1 to 3.   A second taper portion whose diameter is reduced at the end of the cylindrical member is also provided on the outer peripheral portion of the second cylindrical member opposite to the end of the rotating shaft member of the second cylindrical member, The inner surface hollow surface facing the second tapered portion of the cylindrical member and the contact surface of the rotating shaft member are parallel to the rotating shaft, and the second tapered portion and the rotating shaft member are included in the rotating shaft member. A cantilever rotary pump according to claim 3, wherein a third taper member is fixedly fixed to each other.   The cantilever rotary pump according to claim 1, wherein a material of the rotor member is made of a material that is lighter than a material of the rotating shaft member.   When the rotor member, the rotary shaft member, and the cylindrical member are fixed, the rotor member or the tapered portion of the rotary shaft is pressed against the tapered portion of the cylindrical member attached to the rotary shaft with a predetermined pressing force. The cantilever rotary pump according to claim 1, wherein an elastic member is disposed.   The cantilever rotary pump according to claim 1, wherein the rotor of the cantilever rotary pump is a pair of screw rotors that mesh with each other, and the cantilever rotary pump is used as a vacuum pump.

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