Vacuum pump

Abstract

In a vacuum pump, the temperature of a rotor portion is detected more accurately in accordance with a simple method. A thermistor 51 is disposed on a stator in a state where a sensor unit fixed to a frame 53 by a thin film such as a polyimide film opposes a rotor section that is a target of temperature detection. Further, assuming the non-negligible influence, in terms of measurement, that is exerted by heat from the frame, stator and so forth on the first temperature sensor (heat flow from/to the frame), the rotor temperature is estimated more accurately by detecting that influence via other sensors, to compensate for the drop or rise in temperature in the first temperature sensor, and estimate thereby more accurately the temperature of the rotor. Specifically, a second temperature sensor, or a second temperature sensor and a third temperature sensor, are disposed for the first temperature sensor, and the temperature of the rotor section is estimated on the basis of a first detection value by the first temperature sensor, and a second detection value (and a third detection value) by the second temperature sensor (and the third temperature sensor).

1 . A vacuum pump, comprising:
 A casing provided with an inlet port and an outlet port;   a stator portion provided inside the casing;   a shaft rotatably supported inside the casing; and   a rotor disposed on the shaft and provided with a gas transfer mechanism that transfers a gas from the inlet port to the outlet port,   the vacuum pump further comprising:   a rotor portion arranged with a predetermined clearance between the stator portion and the rotor portion;   a motor that rotates the shaft;   temperature detection means having at least two contact-less temperature sensors, one of which is disposed opposing the rotor; and   temperature estimation means for estimating a temperature of the rotor on the basis of an output value from each of the temperature sensors of the temperature detection means.   
     
     
         2 . The vacuum pump according to  claim 1 , wherein
 the temperature detection means is formed of a first sensor unit and a second sensor unit each having a frame body, a fixing member disposed on one face of the frame body, and a temperature sensor fixed to the fixing member, and   a heat conduction amount of at least one of the fixing member and the frame body differs between the first sensor unit and the second sensor unit.   
     
     
         3 . The vacuum pump according to  claim 1 , wherein the temperature detection means is formed of a sensor unit that has a frame body, a fixing member disposed on one face of the frame body, a first temperature sensor fixed to the fixing member, and at least one of a second temperature sensor fixed to the frame body and a third temperature sensor fixed to the stator portion. 
     
     
         4 . The vacuum pump according to any one of  claims 1  to  3 , wherein the temperature detection means is disposed at the stator portion, opposing the rotor, adjacent to the outlet port. 
     
     
         5 . The vacuum pump according to any one of  claims 1  to  3 , wherein the temperature detection means is disposed at the stator portion, opposing the rotor, in a flow path of a purge gas that flows out of the outlet port, the flow path being an inner space of the rotor. 
     
     
         6 . The vacuum pump according to  claim 1 , wherein
 the temperature detection means has a having thermal resistance, and   the at least two contact-less temperature sensors are supported by the support portion and are disposed at the stator portion opposing the rotor.   
     
     
         7 . The vacuum pump according to  claim 1 , wherein
 the temperature detection means has a support portion having thermal resistance, and   one temperature sensor disposed opposing the rotor, from among the at least two contact-less temperature sensors, is supported by the support portion and is disposed at the stator portion opposing the rotor.