JP3130853U - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum pump provided with a non-contact thermometer capable of accurately measuring a temperature without applying unnecessary stress to a magnetic material.
Magnetic bodies M1 to M3 are formed as small pieces of a rectangular rectangular body divided into three bodies, and fixed to a recess 3K of a flange 3P. Stress can be reduced by this division. These quadrangular rectangular magnetic bodies M1 to M3 are preferably arranged in an arc shape so as to be located at an equal distance from the rotation center of the flange 3P. The divided body may be a small cylindrical body. The fixing to the flange 3P may be an adhesive method.
[Selection] Figure 1

Description

  The present invention relates to a vacuum pump such as a turbo molecular pump that houses a turbo mechanism in a casing and rotates the mechanism at high speed to exhaust the room to a high vacuum.

  In this type of turbo molecular pump, the rotating body including the turbo mechanism is heated to a high temperature because the turbo mechanism is rotated at a high speed. When the temperature of the rotating body is increased, the rotating body itself is distorted, and the holding mechanism of the rotating body is also distorted, leading to a decrease in pump function. Therefore, this type of vacuum pump is required to measure and monitor the temperature of the inner rotating body and take measures. First, a description will be given according to FIG. 9 showing an example of a conventional turbo molecular pump TP.

  FIG. 9 shows a schematic configuration of the magnetic bearing type molecular pump TP. Reference numeral 3 denotes a rotating shaft to which a rotor 2 which is a rotating frame body on which a turbo mechanism described later is installed is supported in a non-contact manner by electromagnets 8, 9 and 10 provided on the base 4. The floating position of the rotating shaft 3 is detected by radial displacement sensors 5 and 6 and an axial displacement sensor 7 provided on the base 4. The electromagnets 8 and 9 constituting the radial magnetic bearing, the electromagnet 10 constituting the axial magnetic bearing, and the displacement sensors 5 to 7 constitute a 5-axis control type magnetic bearing.

  A circular disk 11 is provided at the lower end of the rotating shaft 3, and an electromagnet 10 is provided so as to sandwich the disk 11 up and down. By attracting the disk 11 by the electromagnet 10, the rotating shaft 3 floats in the axial direction. The disk 11 is fixed to the lower end portion of the rotating shaft 3 by a nut 12 and rotates integrally with the rotating shaft 3.

  By the way, in the turbo molecular pump TP, the rotor 2 is formed with a plurality of stages of rotating blades R along the rotation axis direction. Fixed wings S are arranged between the rotating wings R arranged vertically. The rotor blade R and the fixed blade S constitute a turbo mechanism TK of the turbo molecular pump TP. Each fixed wing S is held by a spacer P so as to be sandwiched up and down. The spacer P has a function of maintaining the gap between the fixed wings S at a predetermined interval as well as the holding function of the fixed wings S.

  Further, a screw stator NS constituting a drag pump (screw groove pump) NP is provided at the rear stage (lower side in the figure) of the fixed blade S, and between the inner peripheral surface of the screw stator NS and the cylindrical portion ET of the rotor 2. A gap is formed. The fixed wing S held by the rotor 2 and the spacer P is housed in a casing 17 in which an air inlet 16 is formed. When the rotary shaft 3 to which the rotor 2 is attached is rotationally driven by the motor 18 while being supported in a non-contact manner by the electromagnets 8 to 10, the gas on the intake port 16 side is exhausted through the space SP on the back pressure side as indicated by the arrow G. The gas exhausted to the back pressure side is exhausted by an auxiliary pump connected to the exhaust port 19. In FIG. 9, reference numeral 20 denotes a ball bearing. Reference numerals 13 and 14 denote magnetic targets.

  The turbo molecular pump TP is driven and controlled by the controller 1. The controller 1 is provided with a magnetic bearing drive control unit 1M for driving and controlling the magnetic bearing and a motor drive control unit 1C for driving and controlling the motor 18. In addition, 1S in the controller 1 is a detector, and 1K indicates an alarm unit.

  Such a turbo molecular pump TP is an organic combination of the turbo pump function by the turbo mechanism TK and the thread groove pump function by the thread groove pump NP, and is usually called a hybrid turbo molecular pump. As the turbo molecular pump TP, such a hybrid type has good exhaust characteristics and is often used. Thus, the rotor 2 provided with the exhaust mechanism is integrated with the rotary shaft 3 and is rotationally driven by the motor 18 while being supported by the electromagnets 8 to 10 in a non-contact manner. For this purpose, a technique for measuring a rotating body such as an inner turbo mechanism TK in a non-contact manner is used (see Patent Document 1).

In the above configuration, the non-contact temperature measurement method described above is equipped with a magnetic body made of a ferromagnetic material whose permeability changes in the temperature range to be measured on the rotating body, and on the magnetic body and the fixed body side. A magnetic circuit is constituted by a member made of a fixed ferromagnetic material, and means for measuring the magnetic resistance of the magnetic circuit is provided.
This temperature measuring device utilizes a well-known relationship that exists between a certain physical property and temperature. That is, for a rotating body that rotates at high speed in a vacuum, a ferromagnetic material having a Curie point in the temperature range to be measured is used. This type of material loses its ferromagnetism at high temperatures and changes to a paramagnetic material. As a result, of the magnetic flux in the magnetic circuit, the magnetic flux contributed by the material is remarkably reduced and the magnetic resistance is increased. By this principle, the temperature of the rotating body can be realized in a non-contact manner. As will be described later, the rotating body may be a rotating shaft, a rotor, and a disk-like body coupled to the rotating shaft. In the following description, the rotor will be described as an example.

  When the non-contact type temperature measurement method based on the above-described principle is implemented inside the turbo molecular pump TP, it is implemented, for example, with the basic configuration shown in FIG. FIG. 7 is a diagram for explaining the inductance change between the rotating body and the gap sensor 15, and is a schematic diagram of a magnetic circuit generated by the gap sensor 15 and the magnetic body M as a target. The gap sensor 15 is specifically fixed to the stator side of the turbo-molecular pump TP, specifically to the machine base (fixed part) in the pump. The structure of the gap sensor 15 is a core of a high magnetic permeability such as a silicon steel plate. A coil is wound around. A high-frequency voltage having a constant frequency is applied as a carrier wave to the coil of the gap sensor 15, and a high-frequency magnetic field is formed from the gap sensor 15 toward the target magnetic body M. As shown in FIG. 7, the magnetic body M is attached to a recess 3 </ b> K formed on the lower surface of the flange 3 </ b> P in a flange 3 </ b> P integral with the rotary shaft 3.

  On the other hand, a magnetic material having a Curie temperature substantially equal to or close to the allowable temperature of the rotor 2 is used for the magnetic material M as a target. Thus, it should be noted that the allowable temperature is the temperature of the rotor 2 and is a member on which the magnetic body M is installed, that is, the flange 3P in the illustrated example, but does not necessarily coincide with the flange 3P. As shown in FIG. 9, when the rotor 2 is installed on the flange 3P, the flange 3P is made of steel or the like and is made of a material different from that of the rotor 2 made of aluminum, considering the thermal conductivity between the two. Setting is required. In the case of the flange 3P, in the case of aluminum, it is about 120 ° C to 140 ° C. Examples of the magnetic material having a Curie temperature of about 130 ° C. include nickel / zinc ferrite and manganese / zinc ferrite.

When the temperature of the magnetic body M, which is the target, rises due to the temperature rise of the flange 3P and exceeds the Curie temperature, the magnetic permeability of the magnetic body M, which is the target, rapidly decreases to about the vacuum permeability. When the magnetic permeability of the target magnetic body M changes in the magnetic field formed by the gap sensor 15, the inductance of the gap sensor 15 changes.
As a result, a signal change corresponding to a change in magnetic permeability can be detected by detecting and rectifying the amplitude-modulated signal output from the gap sensor 15 provided with a carrier wave. In this way, the temperature can be detected in a non-contact manner.

  An example of temperature measurement by this method is shown in FIG. In FIG. 5, the rotating shaft 3 is shown in a simplified manner as compared with FIG. 9, but the magnetic body M is fixed to the recess 3 </ b> K of the flange 3 </ b> P integral with the rotating shaft 3. 3A is a diagram of the entire rotor 2 viewed from the front, and FIG. 3B is a diagram viewed from the ZZ plane.

JP 2006-194094 A

  Basically, it is required to directly measure the temperature of the rotor 2 as much as possible. The deviation from the temperature of the rotor 2 is large at the lower end of the rotating shaft due to the temperature gradient. For this purpose, the magnetic body M is attached in the vicinity of the rotor 2. The magnetic body M generally has a low tensile strength, and it is necessary to examine a method for reducing the stress on the magnetic body M. For example, as shown in FIG. 5B, the shape of the attachment position and the magnetic body M are arcuate, the arc of the magnetic body M is aligned with the arc of the attachment position, and only the centrifugal force is applied to the magnetic body M itself. A method such as doing so is conceivable.

  However, for example, when bonding is performed using an adhesive and the thickness of the adhesive layer is thin, the circumferential strain due to the centrifugal force generated in the attachment member of the magnetic body M is not relieved, and a large circumferential strain is generated in the magnetic body M. A force in the tensile direction in the circumferential direction acts. Further, due to the difference in the arc shape of the attachment position and the arc shape of the magnetic body M and the contact shape between the arc portion of the magnetic body M and the arc portion of the attachment position of the magnetic body M, a force in the tensile direction acts on the magnetic body M. There is something that will end up.

In this case, a crack H as shown in FIG. 8 is generated, and the magnetic body M itself is crushed, which causes a temperature detection error over time.
Therefore, in order to increase the strength, it is conceivable to change the material of the magnetic body M. However, it is difficult to change the material of the magnetic body M because the Curie temperature needs to be set near the upper limit temperature of the rotor 2 and the material changes the Curie temperature.

  Moreover, although the method of installing in the center part of the rotor 2 with which a centrifugal force reduces and the stress to the magnetic body M is reduced as a result can be considered, for example, as shown in FIG. The magnetic body M is also installed on the lower short surface of the small diameter shaft ST. 6A is a front view, and FIG. 6B is a lower end view as viewed from ZZ. In this case, there is a temperature difference from the actual maximum temperature portion of the rotor 2, and it is necessary to provide temperature estimation / correction means such as adding correction information to the signal from the rotor temperature measurement gap sensor such as motor current. In some cases. The present invention provides a vacuum pump that solves such problems.

  In order to solve the above problems, the turbo molecular pump provided by the present invention is obtained by dividing a magnetic material into small pieces and arranging them in parallel. Therefore, the circumferential strain of the magnetic body generated by the circumferential strain of the magnetic body mounting member is alleviated without affecting the temperature measurement of the rotating body.

  Magnetic material can be prevented from cracking. In addition, it is not necessary to use an estimation means, and it is possible to measure the rotating body temperature with high accuracy. The temperature of the rotating body can be measured, and a highly reliable pump can be provided.

  In order to prevent the magnetic body from being damaged by the tensile force generated by the circumferential strain applied to the magnetic body by the action of the centrifugal force generated by the rotation of the rotating body, it is as small as possible and the magnetic flux in the magnetic circuit is changed. It is desirable that the size is set so as to satisfy that the size is as large as possible. A single or a plurality of types of magnetic bodies having different temperature dependence are arranged in a part of the rotating body, and in order to detect a temperature change of the magnetic body, an inductance due to a temperature change of the magnetic body so that the stator faces the magnetic body An inductance type gap sensor for detecting a change is arranged, and a magnetic material of the same material is divided into small pieces and arranged side by side as shown in FIG. As a result, the stress generated in each magnetic body can be dispersed without lowering the sensitivity of the monitoring function. Thereby, damage to the magnetic material can be prevented.

By the way, the present invention is related to the temperature measurement of this rotating body, but the present invention gives the following three examples for specific embodiments of the rotating body that is the object of temperature measurement.
The first is a “rotating shaft”. More specifically, the flange is formed integrally with the rotating shaft. This flange is generally provided integrally with the top of the rotary shaft.
The second is a “rotor”. This rotor is a rotating frame body that is installed above the rotating shaft, and a turbo mechanism is installed. Further, in the case of a hybrid turbo molecular pump, as shown in the illustrated example, a cylindrical body constituting a thread groove pump is also this “rotor”. include.

The third is “a disk-like body coupled to a rotating shaft”. That is, it is a disk-like body coupled or joined to the rotating shaft. As a method of coupling or joining, there are a method of coupling a rotating shaft and a disk-like body with a screw, a method of forming an uneven portion on each joint surface, and a method of combining the uneven portion or fitting.
These “rotating shaft”, “rotor”, and “disc-like body coupled to the rotating shaft” specified in the claims of the utility model registration shall be interpreted as described above.

Hereinafter, the structure of the present invention will be described according to embodiments shown in the drawings.
FIG. 1 is a view showing a first embodiment according to the present invention. Magnetic bodies M1 to M3 are formed as small rectangular rectangular pieces divided into three bodies, and a flange 3P formed integrally with a rotary shaft 3 is formed. It is fixed to the recess 3K. Stress can be reduced by this division. These quadrangular rectangular magnetic bodies M1 to M3 are preferably arranged in an arc shape so as to be located at an equal distance from the rotation center of the flange 3P. An example of the size of the magnetic bodies M1 to M3 is a rectangular body having a side of about several millimeters. In addition, in FIG. 1, the figure (B) is the figure which looked at the figure (A) which shows a front from the ZZ plane.

  A second embodiment according to the present invention is as shown in FIG. 2, and each of the divided magnetic bodies M4 to M6 has a cylindrical shape and can further reduce stress. In FIG. 2, FIG. (B) is a view of the front view (A) as viewed from the ZZ plane. The mounting position of each magnetic body M4 and M5, M5 and M6, and the contact portion between each magnetic body M4 to M6 become one point, thereby reducing the influence of distortion due to the outer wall surface of the large diameter concave, Can be further reduced. An example of the diameter of the magnetic bodies M4 to M6 in the second embodiment is about several mm. The object to which the magnetic bodies M4 to M6 of the second embodiment are fixed is a flange 3P, a disk-shaped body, a rotor shown in a third embodiment to be described later, or the like.

  The third embodiment according to the present invention relates to a rotating body to which the magnetic bodies M4 to M6 are fixed. In the above embodiment, the rotating body is the rotating shaft, that is, the flange 3P formed integrally with the rotating shaft, but the third embodiment is as shown in FIG. In the third embodiment, as apparent from FIG. 3, the magnetic body M <b> 1 is fixed to the rotor 2. The magnetic body M1 may be in the form of the magnetic body M4 described above. In the illustrated example, a through hole 3H is formed in the flange 3P integrally attached to the rotary shaft 3, and a recess 2K is formed in a portion of the rotor 2 thereabove. A magnetic body M1 (or M4) is fixed on the ceiling side of the recess 2K. A gap sensor GS is installed on the side integrated with the base 4 which is the fixed side corresponding to the magnetic body M1. 3 that have the same reference numerals as those in FIG. 9 have the same functions as those in FIG. 9, and a detailed description thereof will be omitted.

  The fourth embodiment according to the present invention is an embodiment in which magnetic bodies M1 to M3 are attached to a disk-like body fixed to the rotary shaft 3. This embodiment is as shown in FIG. 4, where (A) is a front view and (B) is a view of FIG. (A) as viewed from the ZZ direction. In the figure, the disk-like body 3B is fixed to the rotating shaft 3 by welding or the like through a boss portion 3W. In FIG. 4, 4 is a base.

The structure of the non-contact temperature measuring device for the rotating body in the vacuum pump provided by the present invention is as described above. However, the present invention is not limited to the above and illustrated examples, and includes various modifications. It is.
For example, the magnetic material can be composed of a single magnetic material or a plurality of types of magnetic materials having different temperature dependencies. Furthermore, it can prevent that a magnetic body is damaged and scattered by making a magnetic body into powder and making this into the small piece body which mixed this with the epoxy resin in the attachment position. Further, the number of the small pieces of magnetic bodies fixed is not limited to three as shown in the drawing, and may be four or more or two or less. The present invention includes these various modifications.

It is a figure which shows the 1st Example by this invention. It is a figure which shows the 2nd Example by this invention. It is a figure which shows the 3rd Example by this invention. It is a figure which shows the 4th Example by this invention. It is a figure which shows the other example of the conventional structure. It is a figure which shows the other example of the conventional structure. It is a figure for demonstrating the principle and operation | movement of a gap sensor by the detection of an inductance change. It is a figure which shows the crack of the magnetic body in the conventional structure. It is a longitudinal cross-sectional view which shows the structure of a turbo-molecular pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Controller 1C Motor drive control part 1K Alarm part 1M Magnetic bearing drive control part 1S Detection part 2 Rotor 2K Recessed part 3 Rotating shaft 3B Disc-shaped body 3H Through-hole 3K Recessed part 3P Flange 3W Boss part 4 Base 5 Radial displacement sensor 6 Radial displacement sensor 7 Axial displacement sensor 8 Electromagnet 9 Electromagnet 10 Electromagnet 11 Disk 12 Nut 13 Magnetic target 14 Magnetic target 15 Gap sensor 16 Air inlet 17 Casing 18 Motor 19 Air outlet 20 Ball bearing ET Cylindrical part GS Gap sensor H Crack M Magnetic body M1 Magnetic body M2 Magnetic body M3 Magnetic body M4 Magnetic body M5 Magnetic body M6 Magnetic body NP Screw groove pump NS Screw stator P Spacer SP Space R Rotary blade S Fixed blade ST Small-diameter shaft TK Turbo mechanism TP Turbo molecular pump

Claims (8)

  Inductance for detecting a change in inductance due to a temperature change of the magnetic body on the fixed part side of the vacuum pump so as to face the magnetic body while arranging a magnetic body on a part of the rotating body having a vacuum pump function by rotation In the vacuum pump which arrange | positions a type | formula gap sensor and is comprised so that the change of the magnetic permeability by the temperature of a magnetic body may be detected, the magnetic body attached to the said rotary body was divided | segmented into the small piece, The vacuum pump characterized by the above-mentioned.   The vacuum pump according to claim 1, wherein a part of the rotating body is a flange formed integrally with the rotating shaft.   2. The vacuum pump according to claim 1, wherein a part of the rotating body is a rotor constructed above the rotating shaft.   2. The vacuum pump according to claim 1, wherein a part of the rotating body is a disk-like body coupled to a rotating shaft.   The vacuum pump according to claim 1, wherein the magnetic body attached to the rotating body is formed in a cylindrical shape.   2. The vacuum pump according to claim 1, wherein the magnetic body attached to the rotating body is obtained by mixing and molding magnetic powder and a resin such as epoxy.   5. The vacuum pump according to claim 1, wherein the magnetic body is composed of a single type or a plurality of types of magnetic bodies having different temperature dependencies.   Inductance for detecting a change in inductance due to a temperature change of the magnetic body on the fixed part side of the vacuum pump so as to face the magnetic body while arranging a magnetic body on a part of the rotating body having a vacuum pump function by rotation In the vacuum pump configured to detect the change in magnetic permeability due to the temperature of the magnetic body by arranging the type gap sensor, the magnetic body attached to the rotating body is formed by mixing the powder of the magnetic body with a resin such as epoxy. A vacuum pump characterized by being a thing.

Images