JPH116774A - Rotor temperature detection device and temperature detection method - Google Patents

Abstract

[Problem] To provide a magnetic bearing 1 in a turbo molecular pump A
Improves the temperature detection accuracy of a rotor temperature detection device that detects the temperature of a pump rotor 5 integral with a rotating shaft 4 floatingly held by 1, 12 without using a radiation thermometer. Then, abnormality of the pump rotor 5 and the like are reliably detected. SOLUTION: A thermal expansion amount detecting means 32 for detecting a thermal expansion amount of the pump rotor 5, and a temperature calculating means for calculating a temperature of the pump rotor 5 based on the thermal expansion amount detected by the thermal expansion amount detecting means 32. 33. The thermal expansion amount detecting means 32 includes two non-contact type position sensors 31 for detecting the radial thermal expansion amount of the pump rotor 5,
The two position sensors 31, 31 are provided to face each other with respect to the axis of the pump rotor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor temperature detecting device and a temperature detecting method, and more particularly to the technical field of detecting a temperature of a rotor levitated and held by a magnetic bearing.

[0002]

2. Description of the Related Art Conventionally, for example, in a vacuum pump or the like, in order to stably rotate the pump rotor at high speed, a rotating shaft integral with the pump rotor is floated and held by a magnetic bearing and rotated in a non-contact manner. It is well known that When the temperature of the pump rotor becomes equal to or higher than a predetermined value, it is determined that the pump rotor or the like is abnormal, and in order to protect the pump rotor and other parts, the rotation is stopped or the rotation frequency is reduced. Or

On the other hand, when the pump rotor is levitated and held by magnetic bearings, the only way to directly detect the temperature of the rotor in a non-contact manner is to detect the radiant heat of the rotor with a radiation thermometer. However, since the radiation thermometer is too large, it is difficult to provide it in a limited space such as a vacuum pump.

Therefore, conventionally, in vacuum pumps and the like, the temperature of components disposed near the rotor such as a motor for driving the rotor is detected and the temperature of the rotor is estimated from the detected temperature.

[0005]

However, in the method of estimating the temperature of the rotor from the temperature of other parts such as the motor, the detection accuracy is extremely low, and even if the rotor or the like does not have an abnormality, the rotation of the rotor or the like can be reduced. Stopping or reducing the rotation frequency can occur. Conversely, even if an abnormality has occurred in the rotor or the like, it may not be detected in some cases, and the rotor or the like may be damaged.

The present invention has been made in view of the above circumstances, and an object of the present invention is to detect the temperature of a rotor which is levitated and held by a magnetic bearing, such as a pump rotor of a vacuum pump. By improving the temperature detection method when judging the presence or absence of an abnormality, it is possible to improve the temperature detection accuracy without using a radiation thermometer and to reliably detect the rotor abnormality and the like. is there.

[0007]

In order to achieve the above object, according to the present invention, the amount of thermal expansion of a rotor is detected, and the temperature of the rotor is calculated based on the amount of thermal expansion.

Specifically, according to the first aspect of the present invention, FIGS.
As shown in FIG. 3, it is assumed that the rotor temperature detecting device is configured to detect the temperature of the rotor (5) levitated and held by the magnetic bearings (11) and (12).

The thermal expansion amount detecting means (32) for detecting the thermal expansion amount of the rotor (5) and the rotor (5) based on the thermal expansion amount detected by the thermal expansion amount detecting means (32). And a temperature calculating means (33) for calculating the temperature.

Thus, the amount of thermal expansion directly corresponding to the temperature of the rotor (5) is detected, and the temperature of the rotor (5) is calculated based on the amount of thermal expansion.
This is almost the same as directly detecting the temperature of the motor, and the temperature detection accuracy can be remarkably improved as compared with the case where the temperature of the rotor (5) is estimated from the temperature of other parts such as the motor. Therefore, abnormality of the rotor (5) and the like can be reliably detected.

According to a second aspect of the present invention, in the first aspect of the present invention, as shown in FIGS. 1, 4, 5 and 7, the thermal expansion amount detecting means (32) comprises a non-contact type position sensor (31). ).

As a result, the rotor (5) becomes larger in the axial direction and in the radial direction due to thermal expansion.
By detecting the distance from the sensor (31) to the surface of the rotor (5) according to 1) and comparing the two, the amount of thermal expansion can be easily and accurately detected. Therefore, the configuration of the thermal expansion amount detecting means (32) can be simplified.

According to a third aspect of the present invention, in the second aspect of the present invention, as shown in FIGS. 1 and 4, the thermal expansion detecting means (32) detects the radial thermal expansion of the rotor (5). The two non-contact type position sensors (31) and (31) have the following non-contact type position sensors (31) and (31).
It is assumed that they are provided facing each other with respect to the axis of the rotor (5).

According to the present invention, when the rotor (5) shakes in the radial direction, one of the non-contact type position sensors (3
According to 1), an increase in the amount of thermal expansion of the rotor (5) is detected,
Since the decrease in the amount of thermal expansion is detected by the other non-contact position sensor (31), both position sensors (3
If the detected amounts of 1) and (31) are averaged, for example, it is possible to reliably prevent erroneous recognition that the temperature of the rotor (5) has changed. Therefore, the influence of radial deflection of the rotor (5) can be reduced, and the amount of thermal expansion of the rotor (5) can be detected with higher accuracy.

According to a fourth aspect of the present invention, in the third aspect of the present invention, as shown in FIGS. 1 and 4, the rotor (5) is provided with a bottom having a vacuum pump (A) having one end opened in the axial direction. It is a cylindrical pump rotor, and the two non-contact position sensors (31), (31) are provided corresponding to the opening side in the axial direction of the pump rotor (5).

In this way, the change in the amount of thermal expansion in the radial direction with respect to the temperature change is larger on the opening side of the pump rotor (5) than on the bottom side, so that the accuracy of detecting the amount of thermal expansion is further improved. Can be done. Therefore,
Abnormality can be accurately determined in the vacuum pump (A), and its reliability can be improved.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, as shown in FIG.
1) and (31) are provided on the inner peripheral side of the pump rotor (5).

Thus, in the vacuum pump (A), the gas usually flows on the outer peripheral side of the pump rotor (5).
The gas can be prevented from adversely affecting each of the non-contact position sensors (31). Further, the wiring of each position sensor (31) can be bundled together with the wiring of the magnetic bearings (11) and (12) arranged on the inner peripheral side of the pump rotor (5), thereby effectively preventing disconnection. can do. Therefore, the reliability of the vacuum pump (A) can be further improved.

According to a sixth aspect of the present invention, in the second aspect of the present invention, as shown in FIGS. 5 and 7, the non-contact type position sensor (31) measures the amount of thermal expansion of the rotor (5) in the axial direction. It is assumed to be configured to detect.

Thus, it is not necessary to consider the influence of the centrifugal force in the axial direction of the rotor (5), so that the accuracy of detecting the thermal expansion amount of the rotor (5) can be improved. Further, the non-contact type position sensor (31) is replaced with the rotor (5).
With this arrangement, even with one position sensor (31), the amount of thermal expansion can be accurately detected without being affected by the axial deviation of the rotor (5). Therefore, a simpler thermal expansion detecting means (32) can be obtained while improving the thermal expansion detection accuracy.

A seventh aspect of the present invention is a temperature detecting method for detecting a temperature of a rotor (5) levitated and held by magnetic bearings (11) and (12) as shown in FIGS. is there.

In the present invention, the rotor (5)
Is detected, and the temperature of the rotor (5) is calculated based on the amount of thermal expansion. Thus, the same function and effect as the first aspect can be obtained.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows the overall configuration of a turbo-molecular pump (vacuum pump) (A) having a built-in rotor temperature detecting device according to Embodiment 1 of the present invention. The turbo molecular pump (A) is used for etching a metal film of aluminum formed on the surface of a substrate using a chlorine-based gas in a vacuum atmosphere, for example, in a dry etching step in the manufacture of a semiconductor. Is used to exhaust gas molecules of aluminum chloride (AlCl ₃ ).

The turbo molecular pump (A) includes a casing (3) having an inlet (1) and an outlet (2),
A rotating shaft (4) rotatably provided in the casing (3) and extending vertically, and a pump rotor (5) provided integrally with the rotating shaft (4).
And This turbo-molecular pump (A) incorporates an electric motor (7) for driving the rotation shaft (4) to rotate.

The casing (3) has a substantially cylindrical inner casing (3a) extending in the up-down direction and having upper and lower ends opened, and is formed integrally with the inner casing (3a) in the shape of an outward flange at the lower opening edge. An exhaust port casing (3b) provided; a bottom casing (3c) provided on a lower surface of the exhaust port casing (3b) so as to cover a lower end opening of the inner casing (3a); and the exhaust port casing (3b). A cylindrical lower pump casing (3d) and an upper pump casing (3e) provided so as to vertically overlap each other, and an inlet casing (3f) provided at an upper end opening edge of the upper pump casing (3e). Consists of The intake port (1) is formed by an intake port casing (3f), while the exhaust port (2) is formed.
Is formed in the exhaust port casing (3b) so as to open toward the side (left side in FIG. 1).

A thrust magnetic bearing (11) is provided between the exhaust port casing (3b) and the bottom casing (3c) so as to levitate and hold the rotating shaft (4) rotatably in the thrust direction (vertical direction in FIG. 1). Is arranged. The magnetic bearing (11) is a disk (11) made of a magnetic material provided concentrically and integrally with the lower end of the rotating shaft (4).
a) and electromagnets (11b) and (11b) arranged close to and above the disk (11a). On the other hand, radial magnetic bearings (12) are provided at two upper and lower positions in the inner casing (3a) for floatingly holding the rotating shaft (4) so as to be rotatable in the radial direction. Each radial magnetic bearing (12) has a cylindrical portion (12a) made of a magnetic material that is rotatably and externally fitted to a rotating shaft (4).
And an electromagnet (12b) disposed close to the outer peripheral side of the cylindrical portion (12a). The electric motor (7) is arranged between the two radial magnetic bearings (12), (12). This electric motor (7) is a motor rotor (7) which is rotatably and externally fitted to a rotating shaft (4).
a) and a motor stator (7b) arranged on the outer peripheral side of the motor rotor (7a).

Below the lower end of the rotating shaft (4), a thrust position sensor (13) for detecting the position of the rotating shaft (4) in the thrust direction, and a rotation for detecting the rotation frequency of the rotating shaft (4). And a sensor (14). Specifically, an axial target (15) is integrally provided at the lower end of the rotating shaft (2), while the axial target (15) is provided at a position facing the axis of the rotating shaft (4) of the bottom casing (3c). The position sensor (13) and the rotation sensor (14) are arranged at positions eccentric from the axis.
The bottom surface of the axial target (15) is a plane orthogonal to the axis of the rotating shaft (4), and the gap with the bottom surface is detected by a thrust position sensor (13). In addition, two concave portions (15) for detecting the rotational frequency are provided at two positions on the bottom surface of the axial target (15), which are shifted from each other by 180 °.
a) are provided, and these recesses (15) are provided.
The rotation frequency of the rotating shaft (4) is detected based on the number of times a) and (15a) pass on the rotation sensor (14).

Between the thrust magnetic bearing (11) and the lower radial magnetic bearing (12), a radial position sensor (16) for detecting the position of the lower end of the rotating shaft (4) in the radial direction is provided. Are located. Above the upper radial magnetic bearing (12), a radial position sensor (1) for detecting a position in the radial direction on the upper end side of the rotating shaft (4).
6) is arranged. Further, between the thrust magnetic bearing (11) and the lower radial position sensor (16), when the rotation of the rotating shaft (4) is abnormal, the rotating shaft (4) is connected to the electromagnets (11b) and (12b). And each position sensor (1
Two touch-down bearings (17) and (17) are provided to regulate the movement in the thrust and radial floating directions so as not to contact 3) and (16). Then, the electric motor (7) and the upper radial magnetic bearing (1)
2), one touch-down bearing (1) for similarly restricting the movement of the rotating shaft (4) in the radial floating direction.
7) is arranged.

The pump rotor (5) has a bottomed cylindrical shape with an open lower end, and bolts (18), (18) are attached to the upper end of the rotary shaft (4) at the bottom (upper part). ,…
And are integrally connected by rotation. A plurality of moving blades (19), (19),... Provided so as to extend outward in the radial direction are arranged in multiple stages in the axial direction in the upper half portion on the outer peripheral side. On the other hand, these rotor blades (19),
(19), and the upper pump casing (3
On the inner peripheral side of e), a plurality of vanes (20), (20), ... provided so as to extend inward in the radial direction, respectively.
Are also multi-staged in the axial direction and the rotor blades (19), (1)
9),... Are arranged alternately. A spacer (21) is interposed between the vertically adjacent stationary blades (20), (20). The moving blades (19), (19),... And the stationary blades (20), (2)
0),... Constitute a turbo pump.

The lower half of the outer peripheral surface of the pump rotor (5) is a cylindrical surface. On the other hand, a plurality of thread grooves (22), (22),... Are provided on the inner peripheral surface of the lower pump casing (3d) facing the cylindrical surface. And these cylindrical surfaces and screw grooves (22), (2)
2),... Constitute a screw pump.

On the inner peripheral surface of the lower pump casing (3d) where the screw grooves (22), (22),... Are not provided, that is, on the outer peripheral side of the pump rotor (5), the lower pump casing (3d) is provided. Two pump rotor position sensors (31), (31) for detecting the distance from the inner peripheral surface of 3d) to the outer peripheral surface (cylindrical surface) of the pump rotor (5).
Is provided. These two pump rotor position sensors (3
1) and (31) are non-contact type position sensors, which correspond to the lower end, that is, the opening side end of the pump rotor (5) in the axial direction of the pump rotor (5), that is, in the vertical direction. 5) are provided opposite to each other with respect to the axis. Each of the pump rotor position sensors (31)
The pump rotor (5) is opened from the inner peripheral surface of the lower pump casing (3d) at the open end of the pump rotor (5).
The distance to the outer peripheral surface is detected, and as described later,
The amount of radial thermal expansion of the pump rotor (5) is detected. That is, each pump rotor position sensor (31) constitutes a part of a thermal expansion amount detecting means (32) for detecting a radial expansion amount of the pump rotor (5).

An annular annular path (23) is formed between the inner casing (3a), the exhaust port casing (3b) and the lower pump casing (3d) so as to go around the rotary shaft (4). I have. The annular path (23) communicates with the exhaust port (2) through a communication path (24) provided in the exhaust port casing (3b).

The electromagnets (11b) and (12b) of the magnetic bearings (11) and (12) and the electric motor (7) are configured to be controlled by a controller (30) as shown in FIG. , This controller (30)
Output signals from the thrust position sensor (13), the radial position sensors (16), the rotation sensor (14), and the pump rotor position sensors (31) are input. The electromagnets (11b) of the magnetic bearings (11) and (12),
(12b), electric motor (7) and each sensor (13),
(14), (16) and (31) are as shown in FIG.
It is electrically connected to the controller (30) and a power supply device (not shown) by a connector (25).

The controller (30) controls the rotation frequency of the electric motor (7) based on the output signal from the rotation sensor (14) to control the rotation frequency of the rotation shaft (4), that is, the pump rotor (5). Control and the thrust position sensor (13) and each radial position sensor (1).
6) based on the output signal from each magnetic bearing (11),
The electromagnetic force of the electromagnets (11b) and (12b) of (12) is controlled to float and hold the rotating shaft (4).

Here, the control procedure of the electric motor (7) will be described with reference to FIG. This control is performed when the pump rotor (5) is rotating at a steady rotation frequency.
It is performed every predetermined time (one sampling time).

First, at step S1, the distance from the inner peripheral surface of the lower pump casing (3d) to the outer peripheral surface of the pump rotor (5) is detected by the two pump rotor position sensors (31) and (31), respectively. The distance data of both pump rotor position sensors (31), (31) are averaged to determine the average distance during rotation. Then, in step S3,
The pump rotor (5) is obtained by subtracting the average distance at the time of rotation and the elongation due to the centrifugal force from the average distance at the time of stop, which was previously obtained in the same manner as the average distance at the time of rotation when the pump rotor (5) is stopped. ) Determine the amount of thermal expansion at the lower end. The amount of elongation due to the centrifugal force may be a value checked in advance according to the rotation frequency of the pump rotor (5), a value calculated by a calculation formula, or a steady rotation immediately after the start of rotation of the pump rotor (5). One of the values obtained by subtracting the average distance at the time of stop from the average distance at the time of rotation obtained at the stage when the frequency is reached is used.

Subsequently, in step S4, the temperature of the pump rotor (5) is calculated based on the above-mentioned thermal expansion amount. That is, since the amount of thermal expansion at the lower end of the pump rotor (5) directly corresponds to the temperature of the pump rotor (5), the corresponding relationship is checked in advance, and the relationship is converted into temperature, The temperature is obtained by performing calculations using a calculation formula. At this time, a temperature sensor is provided on the inner peripheral surface of the lower pump casing (3d), and the temperature of the pump rotor (5) is corrected in consideration of the temperature of the lower pump casing (3d) detected by the temperature sensor. You may do so.

Next, the routine proceeds to step S5, where it is determined whether the temperature of the pump rotor (5) is equal to or higher than a predetermined value. When the determination is YES, the process proceeds to step S6 to perform stop control of the electric motor (7) and returns. On the other hand, when the determination is NO, the process proceeds to step S7 to perform normal control of the electric motor (7). To return. That is, when the temperature of the pump rotor (5) exceeds a predetermined value,
It is determined that an abnormality has occurred in the pump rotor (5) and the like, and the electric motor (7) is stopped to protect the pump rotor (5) and the like. So that the electric motor (7)
Control.

In the control procedure of the electric motor (7), in steps S1 to S3, the amount of thermal expansion having the pump rotor position sensors (31) and (31) and detecting the amount of thermal expansion of the pump rotor (5) is determined. A detecting means (32) is configured, and in step S4, the temperature of the pump rotor (5) is calculated based on the thermal expansion amount of the pump rotor (5) detected by the thermal expansion amount detecting means (32). A temperature calculating means (33) is configured. The pump integrated with the rotary shaft (4) levitated and held by the thrust magnetic bearing (11) and each radial magnetic bearing (12) by the thermal expansion amount detecting means (32) and the temperature calculating means (33). A rotor temperature detecting device for detecting the temperature of the rotor (5) is configured.

Therefore, in the first embodiment, when the pump rotor (5) rotates while being floated and held by the thrust magnetic bearing (11) and each radial magnetic bearing (12) together with the rotating shaft (4), The lower pump casing (3) is detected by the pump rotor position sensors (31) and (31).
The distance from the inner peripheral surface of d) to the outer peripheral surface of the pump rotor (5) is detected to determine the amount of thermal expansion of the pump rotor (5), and based on the amount of thermal expansion, the pump rotor (5) is determined.
Is calculated. If the temperature is abnormally high, the electric motor (7) is stopped, so that damage to the pump rotor (5) and the like can be prevented.
As described above, since the amount of thermal expansion directly corresponding to the temperature of the pump rotor (5) is detected and the temperature of the pump rotor (5) is calculated based on the amount of thermal expansion, the temperature of the pump rotor (5) is calculated. Is substantially the same as directly detecting the temperature of the pump rotor (5), and the temperature detection accuracy is significantly improved as compared with the case where the temperature of the pump rotor (5) is estimated from the temperature of other parts such as the electric motor (7). Can be.

In addition, the pump rotor (5) from the inner peripheral surface of the lower pump casing (3d) for determining the amount of thermal expansion.
The distance to the outer peripheral surface is easily and accurately detected by both pump rotor position sensors (31), (31), which are non-contact type position sensors. Then, one position sensor (3
With only 1), when the pump rotor (5) is displaced in the radial direction, an increase or decrease in the amount of thermal expansion is detected. In the above embodiment, however, two pump rotor position sensors (31) are used. , (31) are provided so as to face each other with respect to the axis of the pump rotor (5), and their distance data are averaged. Therefore, when the pump rotor (5) is displaced in the radial direction, 5) It is possible to reliably prevent erroneous recognition that the temperature has changed.

Further, the pump rotor (5) has a bottomed cylindrical shape with one end opened in the axial direction, and both pump rotor position sensors (31) and (31) are provided with the pump rotor (5). Since it is provided corresponding to the opening side in the axial direction, the change in the amount of thermal expansion in the radial direction with respect to the temperature change can be made larger than that at the bottom side, and the detection accuracy of the amount of thermal expansion is further improved. be able to.

Therefore, even if the temperature of the pump rotor (5) is not detected by using the radiation thermometer, the pump rotor (5) can be used.
Abnormality of the turbo molecular pump (A) can be reliably detected, and its reliability can be improved without increasing the size of the pump (A).

(Embodiment 2) FIG. 4 shows Embodiment 2 of the present invention.
(Note that in the following embodiments, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.)
The arrangement of both pump rotor position sensors (31), (31) is different from that of the first embodiment.

That is, in this embodiment, both pump rotor position sensors (31) and (31) are provided on the inner peripheral side of the pump rotor (5), that is, on the outer peripheral surface of the inner casing (3a). The pump rotor (5) is provided so as to face each other with respect to the axis, and is configured to detect a distance from the outer peripheral surface to the inner peripheral surface at the opening end of the pump rotor (5). Then, both pump rotor position sensors (3
1) and (31) detect the amount of thermal expansion of the pump rotor (5) in the radial direction in the same manner as in the first embodiment, and based on the amount of thermal expansion, the pump rotor (5) is detected. The temperature is calculated, and the electric motor (7) is calculated based on the calculated result.
Is controlled.

Therefore, in the second embodiment, the same function and effect as those of the first embodiment can be obtained, and both the pump rotor position sensors (31) and (31) are provided with a pump rotor (31) in which gas molecules do not flow directly. Since it is provided on the inner peripheral side of 5), the gas molecules can be prevented from adversely affecting each pump rotor position sensor (31). In addition, wiring to the connector (25) of each position sensor (31) is performed by connecting the electromagnets (11b) and (12) of the magnetic bearings (11) and (12) arranged on the inner peripheral side of the pump rotor (5).
It can be bundled together with the wiring of b) and the like, and disconnection can be effectively prevented. Therefore, the reliability of the turbo-molecular pump (A) can be further improved.

(Embodiment 3) FIG. 5 shows Embodiment 3 of the present invention.
And both pump rotor position sensors (31), (31)
Is different from the first and second embodiments in that the amount of thermal expansion in the axial direction of the pump rotor (5) is detected.

That is, in this embodiment, both pump rotor position sensors (31) and (31) are provided on the outer peripheral surface of the inner casing (3a) so as to be located below the lower end surface of the pump rotor (5). The position sensor (31) is attached and fixed opposite to the axis of the pump rotor (5).
It is configured to detect the distance from the lower end surface of the pump rotor (5).

In this embodiment, as shown in FIG. 6, control of the electric motor (7) is performed. Note that this control procedure is basically the same as in the first embodiment.
Is the same as

That is, in step T1, both pump rotor position sensors (31) and (31) detect the position sensor (3).
The distances from 1) and (31) to the lower end face of the pump rotor (5) are respectively detected, and in step T2, the distance data of both pump rotor position sensors (31) and (31) are averaged to obtain the average distance during rotation. Ask. Next, in step T3, when the pump rotor (5) is stopped, the average distance during rotation is subtracted from the average distance during stop calculated in advance in the same manner as the average distance during rotation, thereby obtaining the pump rotor (5). The amount of thermal expansion in the axial center direction is determined. When calculating the amount of thermal expansion in step T3, it is not necessary to consider the effect of centrifugal force in the axial direction of the pump rotor (5). No need to pull. Then, in subsequent steps T4 to T7, the same control as steps S4 to S7 described in the first embodiment is performed.

In the control procedure of the electric motor (7), similarly to the first embodiment, the thermal expansion amount detecting means (32) is constituted by steps T1 to T3, and the temperature calculating means (33) is executed by step T4. ) Is configured.

Therefore, in the third embodiment, since each pump rotor position sensor (31) is configured to detect the amount of thermal expansion of the pump rotor (5) in the axial direction, there is no influence of centrifugal force. The detection accuracy of the amount of thermal expansion can be improved by a corresponding amount. Further, since the two pump rotor position sensors (31) and (31) are provided so as to face each other with respect to the axis of the pump rotor (5), the axis of the pump rotor (5) is displaced in the vertical direction. Even if the distance data is different between the two position sensors (31) and (31) by inclining from, the distance data is averaged.
The erroneous recognition that the temperature of the pump rotor (5) has changed can be reliably prevented. Therefore, the accuracy of detecting the amount of thermal expansion can be further improved.

(Embodiment 4) FIG. 7 shows Embodiment 4 of the present invention.
Unlike the third embodiment, one pump rotor position sensor (31) detects the amount of thermal expansion of the pump rotor (5) in the axial direction.

That is, in this embodiment, the pump rotor position sensor (31) is provided above the upper end face of the pump rotor (5) so as to be located at the axis of the rotor (5). The distance from (31) to the upper end surface of the pump rotor (5) is detected. The pump rotor position sensor (31) is fixed to one end of a plurality of sensor support members (35), (35),... The other end of the support member (35) is attached and fixed to the inner peripheral surface of the inlet casing (3f).

Therefore, in the fourth embodiment, similarly to the third embodiment, the pump rotor position sensor (31) is configured to detect the thermal expansion amount of the pump rotor (5) in the axial direction. In addition, it is not necessary to consider the influence of the centrifugal force. Further, the position sensor (31) is a rotor (5).
Are not affected by the axial deviation of the rotor (5). Therefore, even with one position sensor (31), the thermal expansion amount can be detected with high accuracy. Therefore, a simpler thermal expansion detecting means (32) can be obtained while improving the thermal expansion detection accuracy.

[0056]

As described above, according to the first or seventh aspect of the present invention, the thermal expansion of the rotor is compared with the rotor temperature detecting device which detects the temperature of the rotor levitated and held by the magnetic bearing. By detecting the amount and calculating the temperature of the rotor based on the amount of thermal expansion, it is possible to improve the accuracy of detecting an abnormality in the rotor and the like.

According to the second aspect of the present invention, since the thermal expansion amount detecting means has the non-contact type position sensor, the structure of the thermal expansion amount detecting means can be simplified.

According to the third aspect of the present invention, the two non-contact position sensors are provided so as to be opposed to each other with respect to the axis of the rotor, thereby reducing the influence of radial deflection of the rotor. The accuracy of the thermal expansion detection can be further improved.

According to the invention of claim 4, the rotor is a bottomed cylindrical pump rotor having one end opened in the axial direction in the vacuum pump, and the two non-contact position sensors are arranged in the axial direction of the pump rotor. In the vacuum pump, the abnormality determination can be accurately performed in the vacuum pump, and the reliability thereof can be improved. According to the fifth aspect of the present invention, the reliability of the vacuum pump can be further improved by providing both non-contact position sensors on the inner peripheral side of the pump rotor.

According to the sixth aspect of the present invention, the non-contact type position sensor is configured to detect the amount of thermal expansion in the axial direction of the rotor. The detection means can be further simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of a turbo-molecular pump including a rotor temperature detecting device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a control system.

FIG. 3 is a flowchart showing a control procedure of the electric motor.

FIG. 4 is a view corresponding to FIG. 1 showing a second embodiment.

FIG. 5 is a view corresponding to FIG. 1 showing a third embodiment.

FIG. 6 is a diagram corresponding to FIG. 3, illustrating a control procedure of an electric motor according to a third embodiment.

FIG. 7 is a view corresponding to FIG. 1 showing a fourth embodiment.

[Explanation of symbols]

(A) Turbo molecular pump (vacuum pump) (4) Rotary shaft (5) Pump rotor (11) Thrust magnetic bearing (12) Radial magnetic bearing (31) Pump rotor position sensor (non-contact position sensor) (32) Heat Expansion amount detecting means (33) Temperature calculating means

Claims (7)

[Claims] 1. A rotor temperature detecting device for detecting the temperature of a rotor (5) levitated and held by magnetic bearings (11) and (12), wherein the amount of thermal expansion of the rotor (5) is detected. Thermal expansion amount detecting means (32); and temperature calculating means (33) for calculating the temperature of the rotor (5) based on the thermal expansion amount detected by the thermal expansion amount detecting means (32). Characteristic rotor temperature detecting device. 2. The rotor temperature detecting device according to claim 1, wherein the thermal expansion amount detecting means includes a non-contact type position sensor.
1) A rotor temperature detecting device characterized by having the following. 3. The rotor temperature detecting device according to claim 2, wherein the thermal expansion amount detecting means (32) detects two non-contact position sensors (3) for detecting a radial thermal expansion amount of the rotor (5).
1) and (31), wherein the two non-contact position sensors (31) and (31) are provided to face each other with respect to the axis of the rotor (5). Temperature detector. 4. The rotor temperature detector according to claim 3, wherein the rotor (5) is a bottomed cylindrical pump rotor having one end opened in the axial direction in the vacuum pump (A). The rotor temperature detecting device, wherein the contact type position sensors (31), (31) are provided corresponding to the opening side in the axial direction of the pump rotor (5). 5. The rotor temperature detecting device according to claim 4, wherein the two non-contact position sensors (31), (31) are provided on the inner peripheral side of the pump rotor (5). Rotor temperature detector. 6. The rotor temperature detecting device according to claim 2, wherein the non-contact position sensor (31) is configured to detect a thermal expansion amount of the rotor (5) in an axial direction. Rotor temperature detecting device. 7. A temperature detecting method for detecting a temperature of a rotor (5) levitated and held by magnetic bearings (11) and (12), wherein a thermal expansion amount of the rotor (5) is detected. A method for detecting a rotor temperature, comprising calculating a temperature of a rotor (5) based on an amount.