JP2014001643A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly control a temperature of a vacuum pump with a simple constitution.SOLUTION: A vacuum pump comprises: a cooling flow passage formed inside or at an outer edge of the vacuum pump and flowing fluid for cooling a predetermined portion of the vacuum pump; a bypass flow passage bypassing at least one part of the cooling flow passage; a selector valve for switching opening/closing of the cooling flow passage and the bypass flow passage; and bimetal provided at a position at which it does not contact the fluid. A deformation force of the bimetal generated according to a temperature change is mechanically transmitted to the selector valve, and therefore, the selector valve is displaced to control opening/closing.

Description

  The present invention relates to a cooling control technique for a vacuum pump.

  In volumetric transfer type vacuum pumps and momentum transfer type vacuum pumps used in semiconductor manufacturing processes and the like, heat is generated by gas compression, bearing friction, and the like. In applications where large amounts of gas are frequently exhausted or vacuum pumps designed with high compression ratios, these heat generations can cause excessive pump temperature rise, pump casing corrosion, deterioration of the vacuum sealant, bearings and timing gears. There is a risk of damage to the pump and failure of the pump device. For this reason, a type of vacuum pump has been developed in which a cooling fluid (for example, cooling water) is introduced into a portion that needs to be cooled to perform cooling. Such a type is particularly employed in a dry vacuum pump that does not use operating oil in the pump chamber. This is because such a type cannot expect the cooling effect by the working oil.

  On the other hand, some gases to be evacuated by a vacuum pump sublimate from a gas to a solid when a temperature is lowered, thereby generating a reaction product. The reaction product may stick to the inside of the vacuum pump and cause an abnormality in the vacuum pump. As a countermeasure against such sticking, the casing of the pump may be heated with a heater or the like to prevent sublimation of the reaction product and sticking inside the pump. In addition, in order to perform a stable operation of the vacuum pump, it may be necessary to perform a warm-up operation to raise the temperature of the vacuum pump to some extent before performing vacuum exhaust.

  As described above, there are cases where the vacuum pump needs to be cooled and may need to suppress a temperature drop, depending on operating conditions and load characteristics. Moreover, there exists a site | part which needs cooling, and a site | part which needs suppression of a temperature fall. For this reason, a technique has been proposed in which a cooling water flow path is provided inside the pump and the cooling water flow path is switched according to the temperature detected by the temperature sensor (for example, Patent Document 1 below). According to this technique, the temperature of the casing of the pump can be controlled appropriately.

Japanese Patent Laid-Open No. 11-280681 JP 2006-274960 A

  However, the technique of Patent Document 1 requires electronic components such as a switching valve control device and a temperature sensor in addition to the switching valve that switches the flow path of the cooling water. For this reason, the number of parts and the number of wirings increase, and the configuration of the pump control device becomes complicated. Since the complexity of the configuration means an increase in failure factors, the reliability of the vacuum pump may be reduced. Or the load of the regular inspection for maintaining the reliability of a pump increases, As a result, a maintenance cost increases. Moreover, since power for driving the switching valve and power supply to the valve control device are required, there is room for improvement from the viewpoint of power saving.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as, for example, the following forms.

The first aspect of the present invention is provided as a vacuum pump. The vacuum pump is formed inside or outside the vacuum pump, and has a cooling flow path for flowing a fluid for cooling a predetermined part of the vacuum pump, a bypass flow path for bypassing at least a part of the cooling flow path, A switching valve that switches between opening and closing of the flow path and the bypass flow path, and a bimetal provided at a position that does not contact the fluid. In this vacuum pump, the bimetallic deformation force generated according to the temperature change is mechanically transmitted to the switching valve, so that the switching valve is displaced and the opening / closing is controlled.

  According to the vacuum pump having such a configuration, the temperature of a predetermined portion of the vacuum pump can be appropriately controlled with a simple configuration. Further, no electric power is required for controlling the switching valve, which contributes to power saving. In addition, the risk of failure and wiring failure can be reduced and the reliability can be improved as compared with a configuration including a switching valve power source, a temperature sensor, and wiring associated therewith. Alternatively, it is possible to reduce the load of periodic inspections for maintaining the reliability of the pump. Further, since the bimetal is provided at a position where it does not come into contact with the fluid, the bimetal does not come into contact with the fluid and the temperature of the bimetal does not decrease. Therefore, the temperature of the predetermined part is suitably reflected on the bimetal, and the switching valve can be controlled with high accuracy.

  As a second aspect of the present invention, the bimetal may be attached to the vacuum pump in a state where a part of the bimetal is in contact with a predetermined part. According to such a configuration, the heat retained in the predetermined part is easily transmitted to the bimetal, so that the temperature of the predetermined part and the temperature of the bimetal can be made closer. As a result, the control accuracy of the switching valve can be improved. Moreover, the responsiveness with respect to the temperature change of a predetermined part can be improved.

  As a third aspect of the present invention, the vacuum pump further includes an attachment member for attaching the bimetal, and a attachment member attached to the vacuum pump in a state of being in contact with a part of the bimetal and a predetermined portion. It may be. In this case, the attachment member may have a thermal conductivity equal to or higher than the thermal conductivity of the predetermined part. According to this configuration, even if the predetermined part is located away from the bimetal, the heat retained in the predetermined part is suitably transmitted to the bimetal. Therefore, the control accuracy of the switching valve can be improved. Or the freedom degree of arrangement | positioning of the structural member of a vacuum pump can be improved.

  As a 4th form of this invention, an attachment member may be comprised so that attachment or detachment with respect to a vacuum pump is possible. According to such a configuration, the operating temperature of the switching valve can be changed simply by replacing the mounting member to which the bimetal is mounted.

  As a fifth aspect of the present invention, at least the surface of the switching valve may have a thermal conductivity of 30 W / (m · K) or less. According to such a configuration, it is possible to suppress the retained heat of the bimetal transmitted from the predetermined part from being dissipated through the switching valve and the temperature of the bimetal being lowered. As a result, the control accuracy of the switching valve can be improved.

  As a sixth aspect of the present invention, the vacuum pump may further include a connection member that is connected to the switching valve and the bimetal and mechanically transmits the deformation force of the bimetal to the switching valve. Further, as a seventh aspect of the present invention, the vacuum pump may further include a biasing member that biases the switching valve toward one of the opening and closing of the cooling flow path. In this case, the switching valve may be displaced and the switching valve may be controlled by the deformation force of the bimetal acting in the direction opposite to the biasing direction. According to the sixth or seventh embodiment, the switching valve can be displaced according to the deformation force of the bimetal both when the bimetal is bent and when it returns to the original shape with a simple configuration. .

As an eighth aspect of the present invention, the downstream end of the cooling flow path and the downstream end of the bypass flow path may merge from opposite sides. In this case, the switching valve is provided at the junction, and in both the open and closed states of the open / close state, the flow direction of the fluid at the downstream end of the cooling flow path and the downstream end of the bypass flow path It may be located in a direction that intersects both the flow direction of the fluid. According to such a configuration, in both the open state and the closed state, the switching valve receives fluid pressure from both sides of the downstream end of the cooling flow path and the downstream end of the bypass flow path. That is, the switching valve is biased only in one direction and does not receive the fluid pressure. Therefore, the deformation force of the bimetal necessary for displacing the switching valve is one of the case where the cooling flow path or the bypass flow path is switched from the open state to the closed state, and the case where the closed state is switched to the open state. In some cases, it is possible to suppress an excessive increase. That is, in both of the above two cases, the switching force of the switching valve can be reliably switched because the deformation force of the bimetal is not excessively required. Alternatively, the bimetal can be reduced in size.

  The present invention is not limited to the above-described vacuum pump, and can also be realized as a cooling path switching unit that can be attached to and detached from the vacuum pump, a method for controlling the temperature of the vacuum pump, and the like.

It is explanatory drawing which shows schematic structure of the dry vacuum pump as an Example of this invention. It is explanatory drawing which shows schematic sectional structure of a dry vacuum pump. It is explanatory drawing which shows schematic structure of a cooling control mechanism. It is explanatory drawing which shows the schematic structure of a path | route switching unit, and the state at the time of a bypass flow path distribution. It is explanatory drawing which shows the state at the time of the cooling flow path distribution | circulation of a path | route switching unit. It is explanatory drawing which shows the schematic structure of the path | route switching unit as a 2nd Example, and the state at the time of bypass flow passage distribution. It is explanatory drawing which shows the state at the time of the cooling channel distribution | circulation of the path | route switching unit as 2nd Example. It is explanatory drawing which shows schematic structure of the path | route switching unit as a 3rd Example, and the state at the time of a bypass flow path distribution. It is explanatory drawing which shows the state at the time of circulation of the cooling flow path of the path | route switching unit as 3rd Example. It is a schematic diagram which shows the state at the time of removal of the path | route switching unit as 3rd Example. It is explanatory drawing which shows schematic structure of the path | route switching unit as a modification.

A. First embodiment:
FIG. 1 shows a schematic configuration of a vacuum pump 20 as an embodiment of the present invention. FIG. 1 shows a schematic appearance of the vacuum pump 20. In this embodiment, the vacuum pump 20 is a roots type dry vacuum pump. As illustrated, the vacuum pump 20 includes a casing 30, a motor 50, bearings 60 and 70, and a timing gear unit 80. An inlet plate 41 is provided on the upper surface of the casing 30, and an outlet plate 43 is provided on the lower surface of the casing 30. An inlet 42 is formed in the inlet plate 41. An exhaust port 44 is formed in the outlet plate 43. A motor driver 51 that controls the motor 50 is electrically connected to the motor 50.

  FIG. 2 shows a schematic cross section of the vacuum pump 20. In FIG. 2, the cross section of the rotating shaft direction which the vacuum pump 20 has is shown. As illustrated, the vacuum pump 20 includes a pair of rotors 90 (only one rotor is shown in FIG. 2). The rotor 90 is accommodated in the casing 30. In this embodiment, the rotor 90 has a three-stage configuration including a first stage rotor 91, a second stage rotor 92, and a third stage rotor 93.

The pair of rotors 90 are supported by bearings 61 and 71 in the vicinity of both end portions thereof.
It is rotationally driven by a motor 50 which is a shaft brushless DC motor. A pair of timing gears 81 (only one gear is shown in FIG. 2) are fixed to shaft ends of the pair of rotors 90 opposite to the motor 50. The timing gear 81 prevents a synchronization shift between the pair of rotors 90 due to a sudden external factor.

  When the motor 50 is driven, the pair of rotors 90 rotate in the opposite direction without contact while holding a slight gap between the inner surface of the casing 30 and the rotors 90. As the pair of rotors 90 rotate, the suction side gas is confined between the rotor 90 and the casing 30 and transferred to the discharge side. The gas introduced from the intake port 42 (see FIG. 1) is compressed and transferred by the three-stage rotor 90 and discharged from the exhaust port 44 (see FIG. 1).

  Inside the casing 30 surrounding the rotors 91 to 93 of each stage, cooling channels 130, 230, and 330 for circulating a fluid (here, cooling water) for cooling the casing 30 are formed. The cooling channels 130, 230, and 330 can be formed by, for example, pipe casting. In the present embodiment, the cooling flow paths 130, 230, and 330 are particularly provided for cooling the periphery of the rotor 90 in which compression heat is generated. In the present embodiment, these cooling flow paths 130, 230, and 330 are formed as independent flow paths for the respective rotors 91 to 93. However, one cooling channel common to the rotors 91 to 93 of each stage may be formed.

  Cooling water supply channels 120, 220, and 320 are connected to the upstream side of the cooling channels 130, 230, and 330, respectively. A cooling water supply source 110 is connected to the upstream side of the cooling water supply channels 120, 220, and 320. Further, cooling water discharge channels 140, 240, and 340 are connected to the downstream side of the cooling channels 130, 230, and 330. The cooling water supplied from the cooling water supply source 110 is supplied to the cooling flow paths 130, 230, and 330 from the outside of the vacuum pump 20 via the cooling water supply flow paths 120, 220, and 320. The cooling water flows through the cooling flow paths 130, 230, and 330 and is discharged to the outside of the vacuum pump 20 through the cooling water discharge flow paths 140, 240, and 340.

  FIG. 3 shows a schematic configuration of the cooling control mechanism 100 provided in the vacuum pump 20. In FIG. 3, the cross section of the direction orthogonal to the rotating shaft which the vacuum pump 20 has is shown. The cooling control mechanism 100 autonomously controls cooling of a predetermined part (cooling target part) among the components of the vacuum pump 20 without performing electrical control. The illustrated cooling control mechanism 100 controls cooling of the casing 30 as a predetermined portion, more specifically, the casing 30 around the first stage rotor 91. Although explanation and illustration are omitted, the cooling control of the casing 30 around the second stage rotor 92 and the casing 30 around the third stage rotor 93 is also controlled by the cooling control mechanism having the same configuration as the cooling control mechanism 100. Done.

  As shown in FIG. 3, the cooling control mechanism 100 includes a cooling channel 130, a bypass channel 150, and a path switching unit 400. As described above, the cooling flow path 130 is a flow path for flowing the cooling water for cooling the casing 30, and is connected to the cooling water supply flow path 120 located outside the casing 30. The cooling flow path 130 is formed inside the casing 30, circulates around the outer periphery of the rotor chamber 94 that houses the rotor 90, and communicates with the path switching unit 400. In FIG. 3, illustration of the rotor 90 (first stage rotor 91) accommodated in the rotor chamber 94 is omitted.

The bypass channel 150 is a channel that bypasses the cooling channel 130. The bypass flow path 150 is formed to branch from the cooling flow path 130 on the upstream end side of the cooling flow path 130, and communicates with the path switching unit 400 without going around the outer periphery of the rotor chamber 94. Note that the bypass flow path 150 only needs to bypass at least a part of the path of the cooling flow path 130.

  The path switching unit 400 switches the flow state (open / close) of the cooling flow path 130 and the bypass flow path 150. The cooling water flowing through the cooling flow path 130 or the bypass flow path 150 is discharged from the discharge port 170 located on the downstream side of the path switching unit 400 to the outside of the vacuum pump 20. The discharge port 170 is an opening formed in the casing 30.

  FIG. 4 shows a schematic configuration of the path switching unit 400 and a configuration of the casing 30 in the vicinity thereof. The cooling flow path 130 and the bypass flow path 150 formed in the horizontal direction rise upward (in the direction outside the casing 30) around the path switching unit 400, and then bend in the horizontal direction again. Then, the downstream end of the cooling channel 130 and the downstream end of the bypass channel 150 merge at the junction 160. The direction in which the downstream end of the cooling flow path 130 and the downstream end of the bypass flow path 150 flow into the junction 160 is a direction facing each other along the horizontal direction. The discharge port 170 is located above the junction 160.

  As illustrated in FIG. 4, the path switching unit 400 includes a switching valve 410, a bimetal 420, a connection member 430, and a sealing member 440. The switching valve 410 switches the flow state of the cooling flow path 130 and the bypass flow path 150. In the present embodiment, the switching valve 410 has a flat shape. The switching valve 410 is configured to be rotatable about the shaft 411 as a rotation axis in a range where one end side thereof contacts the inner surface 31 or the inner surface 32 of the casing 30. The movable range of the switching valve 410 is a range that intersects both the inflow direction from the cooling flow path 130 to the merge section 160 and the inflow direction from the bypass flow path 150 to the merge section 160 at an arbitrary position. Is set in The shaft 411 is supported by the casing 30 in a cross section (not shown).

  When the switching valve 410 is in contact with the inner surface 31 (the state shown in FIG. 4), the flow between the cooling flow path 130 and the discharge port 170 is closed, and the flow between the bypass flow path 150 and the discharge port 170 is opened. On the other hand, when the switching valve 410 is in contact with the inner surface 32 (the state shown in FIG. 5 described later), the flow between the cooling flow path 130 and the discharge port 170 is opened, and the flow between the bypass flow path 150 and the discharge port 170 is opened. Closed.

  The other end side of the switching valve 410 is accommodated in a space 450 formed by a recessed portion in which the upper side of the casing 30 located between the cooling flow path 130 and the bypass flow path 150 formed upward is recessed. This space 450 is sealed by a sealing member 440 provided in the opening of the recess. The sealing member 440 has a configuration capable of maintaining a sealed state even when the switching valve 410 is displaced. For example, the sealing member 440 is made of a flexible member, and may be bonded to the casing 30 and the switching valve 410 in a state in which the sealing member 440 is sufficiently slackened. As such a member, a well-known rubber or resin having required heat resistance, for example, silicon rubber, fluorine rubber, or the like can be used.

  The bimetal 420 is a member in which a first metal 421 and a second metal 422 having a higher coefficient of thermal expansion than the first metal 421 are joined. The bimetal 420 is provided in a sealed space 450. That is, the bimetal 420 is provided in a state where it does not contact the cooling water flowing through the cooling flow path 130 or the bypass flow path 150. In this embodiment, the bimetal 420 has a flat plate shape.

  The bimetal 420 is bent according to the temperature due to the difference in coefficient of thermal expansion between the first metal 421 and the second metal 422. More specifically, in the bimetal 420, the second metal 422 having a relatively large thermal expansion coefficient expands relatively large, so that the end of the bimetal 420 is changed from the second metal 422 to the first metal. Turn to the side toward 421.

  In the present embodiment, the first metal 421 and the second metal 422 constituting the bimetal 420 are installed in a state in which one end on the same side is embedded in the casing 30. With this configuration, the bimetal 420 and the casing 30 can be reliably fixed and contacted. One end where the bimetal 420 is embedded is in contact with the casing 30. The surface of the second metal 422 opposite to the first metal 421 is in full contact with the casing 30. On the other hand, only the portion embedded in the casing 30 is in contact with the casing 30 on the surface of the first metal 421 opposite to the second metal 422. These contact locations are portions on the inner side of the cooling channel 130 and the bypass channel 150 in the casing 30. The temperature inside the casing 30 is more reflected in the part than in the part on the outside.

  Thus, since the bimetal 420 is provided in a state in which a part thereof is in contact with the casing 30, the temperatures of the bimetal 420 and the casing 30 in the vicinity of the contact point are substantially the same. For this reason, the bimetal 420 is bent according to the temperature of the casing 30.

  Further, the bimetal 420 is installed so that the second metal 422 has a larger contact area with the casing 30 than the first metal 421. For this reason, the temperature of the casing 30 is more easily transmitted to the second metal 422 than the first metal 421. That is, the second metal 422 having a relatively large thermal expansion coefficient tends to be higher than the first metal 421. Therefore, the bimetal 420 can be efficiently deformed. In other words, the deformation amount of the bimetal 420 can be increased.

  The connection member 430 is connected to the switching valve 410 and the bimetal 420. The connection point with the switching valve 410 is a portion of the switching valve 410 on the end side accommodated in the space 450 and is a portion on the end side with respect to the shaft 411. A connection point with the bimetal 420 is an end portion of the bimetal 420 on the side opposite to the side embedded in the casing 30. The connecting member 430 mechanically transmits the deformation force of the bimetal 420 to the switching valve 410. By this transmitted deformation force, the switching valve 410 is displaced with the shaft 411 as the rotation axis.

  The connecting portion between the bimetal 420 and the connecting member 430 is located at the end of the bimetal 420 where the amount of bending is large, so that the deformation force of the bimetal 420 can be efficiently transmitted to the switching valve 410. Further, the distance between the connection point between the bimetal 420 and the connection member 430 and the shaft 411 is smaller than the distance between the shaft 411 and the end of the switching valve 410 on the side exposed to the cooling water flow path. For this reason, compared with the deformation amount of the bimetal 420, the displacement amount of the switching valve 410 on the side exposed to the flow path of the cooling water is increased, so that the switching valve 410 can be efficiently displaced.

  In such a path switching unit 400, when the vacuum pump 20 is in operation, that is, when the temperature of the casing 30 is the same as the environmental temperature at the place where the vacuum pump 20 is installed, the bimetal 420 is not greatly curved, and the switching valve 410 is As shown in FIG. 3, it is in a position in contact with the inner surface 31. At this time, the cooling flow path 130 is completely closed by the switching valve 410, and the bypass flow path 150 is completely opened. Such a state is also referred to as a first state. When cooling water is supplied to the vacuum pump 20 in the first state, all the cooling water flows through the bypass flow path 150, so that the casing 30 is hardly cooled.

Next, when the operation of the vacuum pump 20 is started and the temperature of the casing 30 rises, and the temperature of the 420 rises accordingly, the bimetal 420 moves from the second metal 422 toward the first metal 421. It is deformed so as to bend in the direction of 1. The connection member 430 that has received the deformation force presses the connection location of the switching valve 410 in the first direction. As a result, the switching valve 410 is displaced by a distance corresponding to the amount of deformation of the bimetal 420. As a result, the switching valve 410 moves in a direction in which the cooling flow path 130 is opened and the bypass flow path 150 is closed. Since the switching valve 410 is positioned between the inner surface 31 and the inner surface 32 at the beginning of the movement, both the cooling flow path 130 and the bypass flow path 150 are opened. Such a state is also referred to as a second state. In the second state, the cross sections of the cooling flow path 130 and the bypass flow path 150 between the inner surface 31 and the inner surface 32 are smaller than in the completely opened state. More specifically, as the temperature of the casing 30 (bimetal 420) increases, the opening degree of the cooling flow path 130 increases, so that the cooling of the casing 30 is controlled to the extent corresponding to the temperature of the casing 30. .

  In spite of such control, when the temperature of the casing 30 and the bimetal 420 further rises, the deformation amount of the bimetal 420 further increases, and the connection member 430 receiving the deformation force changes the connection point of the switching valve 410 to the first position. Press further in the direction of. As a result, the switching valve 410 is further displaced and finally moves to a position in contact with the inner surface 32 as shown in FIG. At this time, the cooling flow path 130 is completely opened by the switching valve 410, and the bypass flow path 150 is completely closed. Such a state is also referred to as a third state.

  If it will be in the 3rd state, since cooling water will distribute | circulate to the cooling flow path 130 to the maximum, the temperature of the casing 30 will fall gradually. When the temperature of the casing 30 decreases and the bimetal 420 is deformed in a direction in which the bending is eliminated, the connection member 430 that has received the deformation force changes the connection point of the switching valve 410 to the first direction opposite to the first direction. Pull in the direction of 2. As a result, the switching valve 410 is displaced by a distance corresponding to the amount of deformation in the direction to cancel the bending of the bimetal 420. As a result, the switching valve 410 moves in a direction in which the cooling flow path 130 is closed and the bypass flow path 150 is opened. As a result, the third state shifts to the second state.

  And when the temperature of the casing 30 rises significantly again, the 2nd state shifts to the 3rd state. On the other hand, when the temperature of the casing 30 is sufficiently lowered, the second state shifts to the first state.

  According to the cooling control mechanism 100 described above, the temperature of the casing 30 can be appropriately controlled between a predetermined upper limit value and a lower limit value. The appropriate temperature of the casing 30 may be, for example, 300 ° C. as the upper limit value and 30 ° C. as the lower limit value. In such a case, the cooling control mechanism 100 may be configured such that the temperature at which the second state shifts to the third state is lower than the above upper limit value, for example, 250 ° C. Further, the cooling control mechanism 100 may be configured such that the temperature at which the second state shifts to the first state is higher than the lower limit value, for example, 150 ° C.

  The cooling control mechanism 100 has a simple configuration because it can perform temperature control without performing electrical control using the deformation force of the bimetal 420. Compared with the case where power control is performed for the operation of the switching valve, the power source of the switching valve, the temperature sensor, and the wiring associated therewith are not required, the risk of failure and wiring failure can be reduced, and reliability can be improved. . Alternatively, it is possible to reduce the periodic inspection load for maintaining reliability. The cooling control mechanism 100 also contributes to power saving. Furthermore, since the bimetal 420 is provided in the sealed space 450 at a position not in contact with the cooling water, the bimetal 420 does not come into contact with the cooling water and the temperature of the bimetal 420 does not decrease. That is, the bimetal 420 has substantially the same temperature as the casing 30. Therefore, the operation control of the switching valve 410 can be performed with high accuracy. Further, when the cooling water is supplied even during the warm-up operation of the vacuum pump 20, the cooling water flows only through the bypass flow path 150. The machine time can be shortened.

  Further, the cooling control mechanism 100 is configured to be able to control the opening degree of the bimetal 420 (casing 30) in a state where both the cooling flow path 130 and the bypass flow path 150 are open. For this reason, the cooling control mechanism 100 can perform fine temperature control.

  In the cooling control mechanism 100, the temperature change of the casing 30 is quickly transmitted to the bimetal 420, so that the operation of the switching valve 410 is excellent in responsiveness to the temperature change of the casing 30. As a result, the excessive temperature rise and temperature drop of the casing 30 can be reliably prevented, and the performance of the vacuum pump 20 can be kept good. Moreover, since the bimetal 420 is made of metal and has high heat resistance, it can be suitably applied to the vacuum pump 20 that generates a large amount of heat by operation.

  In the cooling control mechanism 100, it is desirable that at least the surface of the switching valve 410 is made of a material having a thermal conductivity of 30 W / (m · K) or less. Only the surface of the switching valve 410 may be covered with the material, or the whole may be configured with the material. As such a material, for example, SUS304 (λ = about 20 W / m · K) can be exemplified. The lower the thermal conductivity of the material, the better. For example, silicon rubber (λ = 0.2 W / m · K or less) may be used. With these configurations, heat in the space 450 is taken away via the switching valve 410 that comes into contact with the cooling water, and as a result, the temperature of the bimetal 420 can be suppressed from lowering than the temperature of the casing 30. That is, the control accuracy of the switching valve 410 can be improved. As for the sealing member 440, similarly to the switching valve 410, it is desirable to use a material having low thermal conductivity.

  In the cooling control mechanism 100, the downstream end of the cooling flow path 130 and the downstream end of the bypass flow path 150 merge from opposite sides. Further, the switching valve 410 is provided in the junction 160. Then, the switching valve 410 has a cooling water flow direction at the downstream end of the cooling flow path 130 and a cooling at the downstream end of the bypass flow path 150 in both the first state and the third state. It is located in a direction that intersects both the direction of water flow. With this configuration, the switching valve 410 receives cooling water pressure from both sides of the downstream end of the cooling flow path 130 and the downstream end of the bypass flow path 150 at an arbitrary position in the movable region. In other words, when the switching valve 410 switches between opening and closing of the cooling flow path 130 and the bypass flow path 150, the switching valve 410 is not biased toward only one of the opening and closing sides. Therefore, the deformation force required for the bimetal 420 can be reduced. Specifically, the bimetal 420 does not require a deforming force that can displace the switching valve 410 against the pressure biased to only one of the opening and closing sides. As a result, the switching valve 410 can be reliably displaced. Alternatively, the bimetal 420 can be reduced in size.

  In the vacuum pump 20, a cooling control mechanism is individually provided for each of the multistage rotors 91 to 93. Since the pressures in the multi-stage rotors 91 to 93 during the operation of the vacuum pump 20 are different, the compression heat generated at the respective positions corresponding to the multi-stage rotors 91 to 93 is also different. According to the vacuum pump 20, temperature control can be performed with high accuracy even for such a local bias of the casing 30.

B. Second embodiment:
6 and 7 show the configuration of the path switching unit 500 provided in the vacuum pump as the second embodiment. The route switching unit 500 is different from the route switching unit 400 as the first embodiment only in that a spring 530 is provided instead of the connection member 430. Other points are common to the first embodiment. In FIG. 6 and FIG. 7, the same code | symbol as FIG. 4 and FIG. 5 is attached | subjected to the component which is common in 1st Example (FIG. 4 and FIG. 5). Only differences from the first embodiment will be described below.

  As illustrated in FIG. 6, the path switching unit 500 includes a spring 530 as a kind of urging member. One end of the spring 530 is joined to the inner surface of the casing 30 on the opposite side of the bimetal 420 with respect to the switching valve 410 in the space 450. The other end of the spring 530 is joined to an end of the switching valve 410 on the side accommodated in the space 450 (hereinafter also referred to as an accommodation-side end). The spring 530 urges the joint with the switching valve 410 in the direction from the first metal 421 toward the second metal 422. In addition, when the temperature of the casing 30 is lower than a predetermined level and the bimetal 420 is not bent more than a predetermined level, a slight gap is formed between the bimetal 420 and the accommodation side end of the switching valve 410. Is formed. Therefore, the switching valve 410 is maintained at a position where the cooling channel 130 is closed and the bypass channel 150 is opened. Note that the bimetal 420 and the accommodation-side end may be in contact with each other to the extent that the position of the switching valve 410 shown in FIG. 6 is maintained.

  On the other hand, as shown in FIG. 7, when the temperature of the casing 30 is higher than a predetermined level and the bimetal 420 is bent more than a predetermined level, the bent bimetal 420 is in contact with the accommodation side end of the switching valve 410. Furthermore, the accommodating end is pressed against the biasing force of the spring 530 by the deformation force. For this reason, the accommodation-side end portion is displaced in the direction from the second metal 422 toward the first metal 421, and accordingly, the switching valve 410 is moved from the position in contact with the inner surface 31 to the position in contact with the inner surface 32. Displace towards. When the switching valve 410 is displaced to a position where it contacts the inner surface 32, the cooling flow path 130 is opened and the bypass flow path 150 is closed.

  The route switching unit 500 has the same effect as that of the first embodiment. In the above-described example, the deformation force when the switching valve 410 is bent is configured to press the switching valve 410 against the urging force of the spring 530, but such a configuration is merely an example. Depending on the arrangement of the cooling channel 130, the bypass channel 150, the bimetal 420, and the spring 530, the deformation force when the switching valve 410 cancels the bending presses the switching valve 410 against the biasing force of the spring 530. It is good.

C. Third embodiment:
8 and 9 show the configuration of the path switching unit 600 provided in the vacuum pump as the third embodiment. The route switching unit 600 includes the attachment member 660, the point that the route switching unit 600 can be attached to and detached from the casing 30, and the points that accompany them are the same as the route switching unit 400 as the first embodiment. Different. Other points are common to the first embodiment. In FIG. 8 and FIG. 9, the same reference numerals as those in FIG. 4 and FIG. 5 are given to the constituent elements common to the first embodiment (FIGS. 4 and 5). Only differences from the first embodiment will be described below.

  FIG. 8 shows a state where the cooling channel 130 is closed and the bypass channel 150 is opened. FIG. 9 shows a state where the cooling channel 130 is opened and the bypass channel 150 is closed. As shown in FIGS. 8 and 9, the path switching unit 600 includes a switching valve 410, a bimetal 420, a connection member 430, a sealing member 440, a unit casing 630, and an attachment member 660. The configurations of the switching valve 410, the bimetal 420, the connection member 430, and the sealing member 440 are the same as in the first embodiment.

  Unit casing 630 is a casing for path switching unit 600. Inside the unit casing 630, a downstream portion of the cooling flow path 130 and the bypass flow path 150 and a merging portion 160 are formed. In addition, a recess for forming the space 450 is formed in the unit casing 630 so as to communicate with the merging portion 160. The shape of the unit casing 630 is the same as the corresponding portion of the casing 30 as the first embodiment, except for the portion where the attachment member 660 is attached.

  The attachment member 660 is a member for attaching the bimetal 420. In the present embodiment, the attachment member 660 has a plate shape. The attachment member 660 is attached to a recess of the unit casing 630 that communicates with the space 450. In a state where the attachment member 660 and the sealing member 440 are attached to the unit casing 630, the space 450 is a space sealed by the sealing member 440, the inner surface of the unit casing 630, and the attachment member 660. . The bimetal 420 is attached to the attachment member 660 in a state where a part thereof is in contact with the attachment member 660 in the space 450. In this embodiment, the bimetal 420 is embedded in a recess formed in the attachment member 660.

  Such a path switching unit 600 is attached to a recess formed in the casing 30. In a state where the path switching unit 600 is attached to the casing 30, the attachment member 660 is in contact with the casing 30. Further, the cooling flow path 130 and the bypass flow path 150 formed in the unit casing 630 communicate with the cooling flow path 130 and the bypass flow path 150 formed in the casing 30, respectively.

  In the present embodiment, the attachment member 660 has a thermal conductivity equal to or higher than the thermal conductivity of the casing 30. For example, when the material of the casing 30 is cast iron, copper or aluminum may be adopted as the material of the mounting member 660. According to such a configuration, even if the casing 30 is at a position away from the bimetal 420, or a portion of the casing 30 that should be most temperature-controlled (here, the portion on the rotor 90 side, that is, the portion on the inner side of the casing 30). ) Is at a position away from the bimetal 420, the heat retained in the part is suitably transmitted to the bimetal 420. Therefore, the control accuracy of the switching valve 410 can be improved. Or the freedom degree of arrangement | positioning of the structural member of the path | route switching unit 600 can be improved.

  The attachment member 660 is not limited to a plate-like shape, and can have any shape. For example, if the mounting member 660 has a shape (for example, a column shape) extending in the inner direction of the casing 30, the operation of the switching valve 410 can be suitably controlled according to the temperature on the inner side of the casing 30 (vacuum pump 20). . Since high temperature tends to occur on the inner side of the casing 30, the control accuracy of the switching valve 410 can be improved with this configuration.

  In the present embodiment, the above-described path switching unit 600 and the casing 30 are configured to be detachable. Similarly, the unit casing 630 and the attachment member 660, the attachment member 660 and the bimetal 420, and the bimetal 420 and the connection member 430 are also detachable. Such a detachable configuration can be realized by, for example, screwing or a fitting structure.

  FIG. 10 schematically shows a state in which each detachable member of the path switching unit 600 is removed. By making each part attachable and detachable in this manner, maintenance and inspection can be facilitated, and when some members need to be replaced due to wear or the like, it is not necessary to replace all the members. Further, the switching valve 410 can flow through the cooling flow path 130 and the bypass flow path 150 only by replacing the mounting member 660 with the bimetal 420 attached thereto with a mounting member 660 with a bimetal 420 having other characteristics. The temperature to be switched can be changed. Alternatively, the temperature can be changed simply by removing the bimetal 420 from the mounting member 660 and replacing it. The configuration of this embodiment can also be applied to the second embodiment described above.

D. Variations:
D-1. Modification 1:
The configuration of the switching valve 410 is not limited to the configuration in which the above-described flat valve body rotates, and can be set as appropriate. For example, a configuration in which the valve body reciprocates in one direction may be employed.

  FIG. 11 shows a schematic configuration of a path switching unit 700 having a different form from the above-described embodiment. The switching valve 710 includes two valve bodies 711 and 712 and a shaft 713. The valve body 711 is connected to one end of the shaft 713, and the valve body 712 is connected to the other end side of the shaft 713. The valve body 711 is disposed in the cooling flow path 130, and the valve body 712 is disposed in the bypass flow path 150. The cooling flow path 130 and the bypass flow path 150 merge at a merge portion 760 positioned therebetween, and the merge portion 760 is connected to the discharge port 770. A bimetal 720 is connected to the other end of the shaft 713 through a connection member 730 at a position that does not contact the cooling water flow path. The deformation direction of the bimetal 720 is the same as the direction in which the shaft 713 extends.

  The switching valve 710 is configured to reciprocate in the horizontal direction (the direction in which the shaft 713 extends) by the deformation force of the bimetal 720. When the valve body 712 comes into contact with the casing 790 and closes the bypass flow path 150, the valve body 711 and the casing 790 are separated from each other, and the cooling flow path 130 is opened. When the valve body 711 comes into contact with the casing 790 and closes the cooling flow path 130, the valve body 712 and the casing 790 are separated from each other, and the bypass flow path 150 is opened. With such a configuration, suitable temperature control can be performed. The direction in which the deformation force of the bimetal 720 acts may be converted into a different direction using a gear mechanism or the like and transmitted to the switching valve 710.

D-2. Modification 2:
The installation position of the switching valve 410 is not limited to the joining position of the cooling flow path 130 and the bypass flow path 150 but can be set as appropriate. For example, the switching valve 410 may be provided at a position where the cooling flow path 130 and the bypass flow path 150 are branched.

  Further, the arrangement of the cooling flow path 130, the bypass flow path 150, and the discharge port 170 in the path switching units 400, 500, and 600 described above is merely an example, and the shape of the vacuum pump 20, the cooling flow path 130 in the casing 30, and Arbitrary arrangements are possible depending on the routing of the bypass channel 150.

D-3. Modification 3:
The bimetal 420 does not necessarily have to be embedded in the casing 30 or the attachment member 660, and may simply be in contact. Of course, the bimetal 420 does not necessarily have to be in contact with the casing 30 as a cooling target or the attachment member 660 having a thermal conductivity higher than that of the casing 30. For example, in the case where a member having a certain degree of thermal conductivity is interposed between the bimetal 420 and the casing 30, the effects of the above-described embodiment are exhibited to some extent.

D-4. Modification 4:
The part to be cooled of the vacuum pump 20 is not limited to the casing 30. For example, the part to be cooled may be the motor 50, the timing gear unit 80, the bearings 61 and 71, the outlet plate 43, the motor driver 51, and the like. In such a case, the bimetal 420 may be attached so as to be in contact with the cooling target site or in the vicinity of the cooling target site. Further, the cooling flow path 130 and the bypass flow path 150 are not necessarily formed inside the casing 30. For example, it may be formed inside the casing for the part to be cooled, or a flow path constituted by a pipe or the like may be joined to the outside of the part to be cooled. The same applies to the case where the portion to be cooled is the casing 30.

For example, the temperature of the motor 50 may be controlled to 120 ° C. or lower. The timing gear unit 80 and the bearings 61 and 62 may be temperature-controlled at a temperature of 120 ° C. or less determined according to the heat resistance of the lubricating oil used, for example. The temperature of the outlet plate 43 may be controlled to 250 ° C. or less, for example. For example, the temperature of the motor driver 51 may be controlled to 100 ° C. or lower. Since the bimetal 420 is excellent in heat resistance, temperature control can be performed in an arbitrary range of 50 to 300 ° C. according to the heat generation characteristics around the portion to be cooled.

D-5. Modification 5:
The shape of the bimetal 420 is not limited to the flat plate shape described above, and can be an arbitrary shape. For example, a U-shaped or spiral bimetal may be used.

D-6. Modification 6:
The above-described embodiments are not limited to dry vacuum pumps, but can be applied to various vacuum pumps that perform temperature control by circulating a fluid, such as turbomolecular pumps or large rotary pumps (oil rotary pumps).

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof. In addition, combinations or omissions can be made as appropriate as long as at least part of the problems and effects described above are achieved.

DESCRIPTION OF SYMBOLS 20 ... Vacuum pump 30,790 ... Casing 31,32 ... Inner surface 41 ... Inlet plate 42 ... Inlet port 43 ... Outlet plate 44 ... Exhaust port 50 ... Motor 51 ... Motor driver 60, 70 ... Bearing part 61, 71 ... Bearing 80 ... Timing gear section 81 ... Timing gear 90 ... Rotor 91 ... First stage rotor 92 ... Second stage rotor 93 ... Third stage rotor 94 ... Rotor chamber 100 ... Cooling control mechanism 110 ... Cooling water supply source 120 ... Cooling water supply flow path DESCRIPTION OF SYMBOLS 130 ... Cooling flow path 140 ... Cooling water discharge flow path 150 ... Bypass flow path 160, 760 ... Merge part 170, 770 ... Discharge port 400, 500, 600, 700 ... Path switching unit 410, 710 ... Switching valve 411 ... Shaft 420 , 720 ... Bimetal 421 ... First metal 422 ... Second metal 430, 730 ... Connection member 440 ... Sealing member 450 ... Space 530 ... Spring 630 ... Unit casing 660 ... Mounting member 711, 712 ... Valve body 713 ... Shaft

Claims (8)

A vacuum pump,
A cooling flow path formed inside or outside the vacuum pump and for flowing a fluid for cooling a predetermined portion of the vacuum pump;
A bypass flow path for bypassing at least a part of the cooling flow path;
A switching valve for switching between opening and closing of the cooling channel and the bypass channel;
A bimetal provided at a position not in contact with the fluid;
With
A vacuum pump in which the switching valve is displaced by mechanically transmitting the deformation force of the bimetal generated in response to a temperature change to the switching valve, thereby controlling the opening and closing. The vacuum pump according to claim 1,
The bimetal is attached to the vacuum pump in a state where a part of the bimetal is in contact with the predetermined part. The vacuum pump according to claim 1,
Furthermore, an attachment member for attaching the bimetal, comprising a part of the bimetal and an attachment member attached to the vacuum pump in contact with the predetermined part,
The mounting member has a thermal conductivity equal to or higher than a thermal conductivity of the predetermined portion. The vacuum pump according to claim 3,
The attachment member is a vacuum pump configured to be detachable from the vacuum pump. A vacuum pump according to any one of claims 1 to 4,
At least the surface of the switching valve has a thermal conductivity of 30 W / (m · K) or less. A vacuum pump according to any one of claims 1 to 5,
Furthermore, a vacuum pump comprising a connection member connected to the switching valve and the bimetal and mechanically transmitting the deformation force of the bimetal to the switching valve. A vacuum pump according to any one of claims 1 to 5,
And a biasing member that biases the switching valve toward one of the opening and closing sides of the cooling channel,
A vacuum pump in which the switching valve is displaced and the opening / closing is controlled by the deformation force of the bimetal acting in a direction opposite to the biasing direction. A vacuum pump according to claims 1 to 7,
The downstream end of the cooling flow path and the downstream end of the bypass flow path merge from opposite sides,
The switching valve is
Provided at the confluence point,
In both the open state and the closed state of the opening and closing, both the flow direction of the fluid at the downstream end of the cooling flow path and the flow direction of the fluid at the downstream end of the bypass flow path A vacuum pump located in the crossing direction.

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