JP2002257079A - Turbo-molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo-molecular pump small in energy loss for controlling temperature within a pump body. SOLUTION: This turbo-molecular pump supports a rotor in a non-contact state with a magnetic bearing 3 within the pump body 1, and is equipped with a heater 6 for heating the pump body 1; a cooling means 10 for cooling the pump body 1; a temperature detecting means 7 for detecting temperature within the pump body 1; and a control means 11 for controlling the heater 6 and the cooling means 10 based on the detected temperature within the pump body 1. The control means 11 operates the heater 6 only when the temperature within the pump body 1 is lower than the set lower limit temperature, and operates the cooling means 10 only when the temperature within the pump body 1 is higher than the set upper limit temperature higher than the set lower limit temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a turbo-molecular pump using a magnetic bearing.

[0002]

2. Description of the Related Art In a turbo-molecular pump using a magnetic bearing, a rotating body constituting the pump is supported in a non-contact manner by a magnetic bearing in a pump body, and is driven to rotate by an electric motor.

As this kind of turbo molecular pump, a heater for heating the pump body, a cooling means for cooling the pump body, a temperature detecting means for detecting the temperature inside the pump body,
There is a known pump having a control unit for controlling a heater and a cooling unit based on the detected temperature in the pump body. The heater prevents the compressed gas from solidifying and adhering and accumulating in the pump body, and the cooling means prevents an excessive rise in temperature inside the pump body.

[0004] Usually, the heater is of an electric type, and is in an operative state when energized and in a non-operative state when not energized. Also,
The cooling means includes a cooling water supply passage for supplying cooling water to the pump body, and an electromagnetic control valve is provided in this passage. When the control valve is not energized, it is closed.
The flow path is closed, and when the power is supplied, the flow path is opened, the flow path is opened, and cooling water is supplied to the pump body through the flow path.

Conventionally, when the temperature inside the pump is lower than the set temperature, the control means activates the heater and closes the control valve of the cooling water supply flow path, so that the temperature inside the pump becomes lower than the set temperature. When the temperature is high, the heater is deactivated and the control valve is opened.

[0006]

In the conventional turbo-molecular pump, as described above, the on / off control of the heater and the on / off control of the control valve are performed based on one set temperature. In addition, there is a problem that the control valve causes chattering. Also, when the temperature inside the pump body is lower than the set temperature, the heater is operated (energized state).
When the temperature inside the pump body is higher than the set temperature, the control valve is in the open state (energized state), and one of them is always in the energized state. There is a problem that the loss is large.

An object of the present invention is to provide a turbo-molecular pump having a small energy loss for temperature control in a pump body.

Another object of the present invention is to provide a turbo-molecular pump capable of preventing chattering of a heater and a control valve.

[0009]

Means for Solving the Problems and Effects of the Invention A turbo molecular pump according to the present invention is a turbo molecular pump in which a rotating body is supported in a non-contact manner by a magnetic bearing in a pump body, and a heater for heating the pump body. A turbo-molecule comprising: cooling means for cooling a pump body; temperature detecting means for detecting a temperature in the pump body; and control means for controlling a heater and a cooling means based on the detected temperature in the pump body. In the pump, the control unit activates the heater only when the temperature in the pump body is lower than a predetermined lower limit temperature, and when the temperature in the pump body is higher than a predetermined upper limit temperature higher than the lower limit temperature. The cooling means is set to the operating state only in the case of (1).

The heater is of an electric type, and is in an activated state when energized, and inactivated when not energized. Also,
The cooling unit is in an operating state when energized, and is inoperative when not energized.

The control means is constituted by digital processing means capable of executing a software program, such as a microcomputer and a digital signal processor. Digital Signal Processor (Digital Signal Pr
Ocessor) means dedicated hardware capable of software programming and capable of high-speed real-time processing. Hereinafter, this is abbreviated as “DSP”.

According to the turbo-molecular pump of the present invention, the heater is activated (energized state) only when the temperature inside the pump body is lower than the set lower limit temperature, and the cooling means sets the temperature inside the pump body. Only when the temperature is higher than the upper limit temperature is the operating state, and when the temperature in the pump is between the set lower limit temperature and the set upper limit temperature, both the heater and the cooling means are set to the non-operating state (non-energized state). Therefore, energy loss for temperature control in the pump body can be reduced.

For example, the cooling means includes a cooling fluid supply passage for supplying a cooling fluid to the pump body, and a control valve for opening and closing the cooling fluid passage. , And is in the open state when energized.

In this case, the control valve is opened (energized state) only when the temperature inside the pump body is higher than the set upper limit temperature.
, And the closed state (non-energized state) otherwise.
For this reason, when the temperature in the pump is between the set lower limit temperature and the set upper limit temperature, both the heater and the control valve are turned off. Therefore, energy loss for temperature control in the pump body can be reduced.

Further, for example, the time from when the control means activates the heater to the time when the heater is next inactivated and the time from when the control valve is opened to when the control valve is next closed are respectively set. Longer than the specified minimum operating time.

In this case, the time when the heater is in the operating state and the time when the control valve is in the open state are not shorter than the minimum operating time. Therefore, by appropriately setting the respective minimum operation times, chattering of the heater and the control valve can be prevented.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram schematically showing a configuration of a main part of a turbo-molecular pump.

The turbo-molecular pump comprises a pump body (1) and a controller (2).

The pump body (1) includes a digital control type magnetic bearing (3) for supporting a rotating body (not shown) constituting a rotating part of the pump in a non-contact manner, and a position detecting device (3) for detecting a position of the rotating body. 4), an electric motor (5) that rotationally drives the rotating body,
A heater (6) as a heating means for heating a required portion in the pump body (1) and a temperature detecting device (7) as a temperature detecting means for detecting a temperature of the required portion in the pump body (1) are provided. Have been.

The turbo molecular pump also has a pump body
(1) A cooling device (8) for supplying cooling water as a cooling fluid into the cooling water supply passage (9) as a cooling fluid supply passage and an electromagnetic control valve (6) for opening and closing the passage (9). 10) are provided, and these constitute cooling means for cooling the inside of the pump body (1).

The controller (2) includes a DSP (11) as digital control means for controlling each part of the pump body (1),
A magnetic bearing drive circuit (12), a motor drive circuit (inverter circuit) (13), a heater drive circuit (14), a valve drive circuit (15), and the like are provided.

The magnetic bearing (3) supports the rotating body in a non-contact manner in the axial control axis direction at one location in the axial direction (axial direction) of the rotating body by the magnetic attraction force of a plurality of electromagnets. At two positions, the rotating body is supported in a non-contact manner in two control axis directions orthogonal to each other in radial directions (radial directions).

The DSP (11) controls the excitation current supplied to each electromagnet of the magnetic bearing (3) via the magnetic bearing drive circuit (12) based on the output signal of the position detection signal, that is, the position of the rotating body. Thus, the rotating body is supported at a predetermined target position in a non-contact manner.

The DSP (11) further includes a motor drive circuit (13)
, The rotation of the motor (5) is controlled.

The DSP (11) further includes a temperature detector (7)
The heater (6) is controlled via the heater drive circuit (14) based on the output signal of the pump body (1), that is, the temperature inside the pump body (1) (hereinafter, abbreviated as "internal temperature"), and the valve drive circuit (15)
The valve (10) is controlled via the.

When the heater-on signal is output from the DSP (11), the heater (6) is turned on, the heater (7) is turned on (on), and the inside of the pump body (1) is heated. Is done. Conversely, when the heater (OFF) signal is output from the DSP (11), the heater (6) is de-energized, the heater (7) is deactivated (off), and the pump (1) is turned off. But,
No longer heated.

When the DSP (11) outputs a valve-on signal (valve open signal), the valve (10) is opened (on),
The flow path (9) is opened, cooling water is supplied from the cooling device (8) into the pump body (1), and the inside of the pump body (1) is cooled.
Conversely, when a valve off signal (valve close signal) is output from the DSP (11), the valve (10) is closed (off state) and the flow path is closed.
(9) is closed, the cooling water is not supplied into the pump body (1), and the inside of the pump body (1) is not cooled.

FIG. 2 is a time chart showing a change in the internal temperature during the operation of the turbo-molecular pump and a change in the control state of the heater (6) and the valve (10) due to the change. Next, the control of the heater (6) and the valve (10) by the DSP (11) will be described in detail with reference to FIG.

In the DSP (11), a set lower limit temperature T0 for controlling the heater (6) and a set upper limit temperature T1 for controlling the valve (10) are preset. Set upper limit temperature T1
Is a predetermined amount (for example, 0.5 to
(About 1 ° C) is set to a high value. Also, DSP (11)
The heater minimum operation time thm, which is the minimum operation time from turning on the heater (6) to turning it off next time,
in and a valve minimum operation time tvmin which is a minimum operation time from when the valve (10) is turned on to when it is turned off next time. For example, the heater minimum operation time thmin is 1
About 5 seconds, and the minimum valve operating time tvmin is about 10 to 20 seconds.

The DSP (11) monitors the internal temperature, which is the output signal of the temperature detecting device (7), during the operation of the turbo-molecular pump, and when the internal temperature is lower than the set lower limit temperature T0, the heater (6). ) Is turned on, and when the internal temperature is higher than the set lower limit temperature T0, the heater (6) is turned off.When the internal temperature is higher than the set upper limit temperature T1, the valve (10) is turned on. When the internal temperature is lower than the set upper limit temperature T1, the valve (10) is turned off. When the heater (6) is turned on, the heater (6) is kept on until the heater minimum operation time thmin elapses even if the internal temperature becomes higher than the set lower limit temperature T0. Similarly, the valve (1
0) is turned on, the internal temperature is
Even if it becomes lower than 1, the valve (10) is kept on until the valve minimum operation time tvmin elapses. Accordingly, when the internal temperature is between the set lower limit temperature T0 and the set upper limit temperature T1, both the heater (6) and the valve (10) are turned off, and unnecessary energy loss can be reduced. Also, heater
The time from when the (6) is turned on to the next off state and the time from when the valve (10) is turned on to the next off state are respectively the minimum operation time thmin,
By setting each of the minimum operation times thmin and tvmin to appropriate values without being shorter than tvmin,
Chattering of the heater (6) and the valve (10) can be prevented.

The overall configuration of the turbo-molecular pump and the configuration of each part are not limited to those of the above-described embodiment, and can be changed as appropriate.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a turbo-molecular pump showing an embodiment of the present invention.

FIG. 2 is a time chart showing a change in internal temperature and a change in control of a heater and a control valve by a DSP.

[Explanation of symbols]

 (1) Pump body (2) Controller (3) Magnetic bearing (6) Heater (7) Temperature detection device (8) Cooling device (9) Cooling water supply channel (10) Control valve (11) Digital signal processor

Claims (3)

[Claims] 1. A turbo-molecular pump in which a rotating body is supported in a non-contact manner by a magnetic bearing in a pump body, wherein a heater for heating the pump body, a cooling means for cooling the pump body, and a temperature in the pump body. In a turbo molecular pump comprising: a temperature detecting means for detecting, and a control means for controlling a heater and a cooling means based on the detected temperature in the pump body, the control means sets the temperature in the pump body to a predetermined value. A turbo molecule, wherein the heater is activated only when the temperature is lower than the lower limit temperature, and the cooling means is activated only when the temperature in the pump body is higher than a predetermined upper limit temperature which is higher than the set lower temperature. pump. 2. The cooling means includes a cooling fluid supply flow path for supplying a cooling fluid to a pump body, and a control valve for opening and closing the cooling fluid flow path, wherein the control valve is in a closed state when not energized. The turbo molecular pump according to claim 1, wherein the turbo molecular pump is in an open state when energized. 3. The time from when the control means activates the heater to the time when the heater is next inactivated and the time between when the control valve is opened and then when the control valve is closed are respectively set. 3. The turbomolecular pump according to claim 2, wherein the turbomolecular pump is longer than the minimum operation time.