JPS614874A - Cryopump - Google Patents

Abstract

PURPOSE:To eliminate the uselessness of the operation power of a compressor by controlling the amount of working gas discharged from the compressor according to the temperature of a cryopanel or the pressure of the exhausted gas by controlling the output frequency of a power frequency conversion means according to the above-described temperature and the pressure. CONSTITUTION:A cryopump is equipped with a compressor 10 which inhales working gas having a normal temperature and low pressure, expansion means 20 which adiabatically expands the working gas having normal temperature and high pressure which is discharged from the compressor 10 and generates coldness, and cryopanels 30 and 31 which are installed at the top edge parts of the first-stage and the second-stage expansion machines 21 and 22 of a coldness accumulator type expansion machine 20 and condenses the gas on the periphery. Further, the power-frequency conversion means for a motor for driving the compressor 10, for example, an inverter 40, temperature sensor 50 for detecting the temperature of the cryopanel 31, and a controller 60 which receives the signal of the temperature sensor 50 and controls the output frequency of the inverter 40 according to the temperature of the cryopanel 31 are provided.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a cryopump.

[Background of the invention]

Conventionally, cryopumps consist of a compressor that sucks in helium gas at room temperature and low pressure and discharges helium gas at room temperature and high pressure, and generates cold by adiabatically expanding the helium gas at room temperature and high pressure discharged from this compressor. A cryopanel that is attached to the cold station of the expander and collects the surrounding gas by condensing or solidifying it is known (US Pat. No. 42,857).
10 specification, Japanese Patent Publication No. 58-25873).

However, such a cryopump does not recognize that the amount of working gas discharged from the compressor should be controlled in accordance with the temperature of the cryopanel and the pressure of the object to be pumped.

[Purpose of the invention]

The purpose of the present invention is to control the amount of working gas discharged from the compressor according to the temperature of the cryopanel and the pressure of the exhaust object.
An object of the present invention is to provide a cryopump capable of eliminating waste of operating power of a compressor.

[Summary of the invention]

The present invention provides power supply frequency conversion means for a motor that drives a compressor that sucks working gas at room temperature and low pressure and discharges working gas at room temperature and high pressure, and adiabatically expands the working gas discharged from the compressor to cool it. The temperature or temperature of the cryopanel attached to the generating expansion means is determined by a detection means for detecting the pressure inside the exhaust object, and in response to a signal from the means, the temperature or roasting of the cryopanel is adjusted according to the pressure inside the exhaust object. and a control device for controlling the output frequency of the power supply frequency conversion means according to the temperature of the cryopanel or the pressure inside the exhaust body. , the amount of working gas discharged from the compressor is controlled according to the temperature of the cryopanel or the pressure inside the body to be exhausted.

[Embodiments of the invention]

An embodiment of the present invention will be explained with reference to FIG. 1 and FIG.

In Figure 1, the cryopump includes a compressor 10 that sucks in working gas at room temperature and low pressure and discharges working gas at room temperature and high pressure, and adiabatically expands the working gas at room temperature and high pressure discharged from the compressor 45!10. expansion means for generating refrigeration, e.g.
A two-stage regenerator type expander (hereinafter referred to as the expander) 20 and an expansion 'M! , 20, the first stage expansion tank 21 and the second stage expander n are each attached to the tip of the cryopanel (9), 31 which condenses or solidifies and collects the surrounding gas, and the compressor 10 is Power frequency conversion means for the driving motor, for example, an inverter and a cryopanel 3 in this case.
- A temperature sensor which is a detection means for detecting the temperature of the cryopanel 31, and a control device ω which receives a signal from the temperature sensor and controls the output frequency of the inverter according to the temperature of the cryopanel 31. It is equipped with The first stage expander 4 of the expansion a2o and the cryopanel (9), 311 temperature sensor (material) are installed in a container 7 which is open on the side corresponding to the cryopanel block.
It is stored in 0. A baffle is installed in the cryopanel garden so as to be located between the cryopanel 31 and the entrance of the container 70. The compressor 10 and the inverter switch are connected, the inverter switch and the control device ω are connected, and the control device! The temperature sensor and - (capital) are connected. The working gas inlet of the compressor 10 and the expansion machine are connected by a working gas introduction line, and the working gas outlet of the expansion a20 and the suction port of the compressor 10 are connected by a working gas return line 91. has been done. The cryopump is provided to be able to evacuate the vacuum chicken par 00 by connecting the container 70 with its opening side communicating with an object to be evacuated, for example, the vacuum chicken par 100.

First, the compressor lO and the expander (9) are started operating from a state of room temperature. Here, it is assumed that the roughing work in the vacuum chamber 100 has been completed.

When the operation starts, the temperature at the tip of the second stage expander n begins to decrease, and although it varies depending on the size of the cryopump, it becomes almost constant in 1 to 2 hours. On the other hand, the working gas flow rate Q required by the expansion side of the expander increases immediately after the start of operation in response to the drop in temperature T at the tip of the second stage expander 2, as shown by the broken line in Fig. 2, and increases over the operating time. After 11 to 2 hours, the temperature becomes constant and becomes constant at the same time.

The rate of increase in the required working gas flow rate from immediately after the start of operation to the end of operation is about 2 to 3 times.

In other words, the required working gas flow rate in the steady state of operation is 1.
If it is set at 00 inches, it will be sufficient to use about 30 to 50 inches immediately after the start of operation.

This rate of increase is determined by the shape of each expander, so if you experiment with the same model once, you will be able to determine the relationship between the temperature level of the second stage expander ρ and the required working gas flow rate. Desired.

Further, since the discharge gas flow rate of the compressor IO is proportional to the rotation speed of the motor, when a general-purpose AC motor is used, it is directly proportional to the power frequency.

Therefore, from the above, the relationship between the temperature level of the second stage expander B and the power frequency can be determined. Therefore, the temperature at the tip of the second stage expansion machine η is detected by a group of temperature sensors and transmitted to the control device ω, and the control device 160 uses the preset temperature at the tip of the second stage expansion machine 1122 and the compressor. Select an appropriate power frequency based on the power supply frequency and command the inverter to turn off.

According to this embodiment, the rotation speed of the compressor can be changed according to the temperature level at the tip of the expander, so the compressor supplies as much working gas as required by the expander.
This has the effect of eliminating waste of compressor operating power.

Next, another embodiment of the present invention is shown in FIG. For example, when it is desired to maintain the pressure within the vacuum chamber 100 at a level considerably higher than the ultimate pressure of the cryopump, the vacuum chamber 1
00 internal pressure is detected by the pressure sensor 51 and transmitted to the control device ω, and the control device 160 changes the output frequency of the inverter off according to the difference between the preset pressure and the detected internal pressure of the vacuum chamber 100. It is something to do.

In this case, the pressure sensor 51 was attached to the vacuum chamber 100, but for simplicity, it may be attached to the housing 70 of the cryopump and the same effect can be achieved.

That is, if the detected pressure is lower than the set pressure, the frequency will be lowered, and if the opposite is the case, the frequency will be increased.

In FIG. 3, other devices and the like that are the same as those in FIG. 1 are designated by the same reference numerals and their explanations will be omitted.

According to this embodiment, it is possible to obtain the same effect as that of the above-mentioned embodiment, and furthermore, the pressure fluctuation in the vacuum chamber can be made smaller compared to the case where the compressor is turned on and off. This has the effect of being more energy efficient than the throttle valve method.

〔Effect of the invention〕

As explained above, the present invention provides power supply frequency conversion means for a motor that drives a compressor that sucks working gas at room temperature and low pressure and discharges working gas at room temperature and high pressure, and a means for converting the working gas discharged from the compressor. The temperature or sound of the cryopanel attached to the expansion means that adiabatically expands to generate cold is detected by a detection means that detects the pressure inside the exhaust body and a detection means that detects the pressure inside the exhaust body. By being equipped with a control device that controls the output frequency of the power supply frequency conversion means according to the pressure, the temperature or noise of the cryopanel can be reduced by controlling the discharge working gas amount of the compressor according to the pressure inside the exhaust object. This has the effect of eliminating waste of operating power for the compressor.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the cryopump according to the present invention, and FIG. 2 shows the required working gas flow rate of the expander in FIG. 1, the temperature at the tip of the second stage expander, and the operating time. FIG. 3 is a schematic diagram showing the relationship between the above and FIG. 3, which is a configuration diagram showing another embodiment of the cryopump according to the present invention. 10... Compressor, expansion machine, 30
．． 31...Cryopanel, First...Inverter, Seki...Temperature sensor, 51...
...Pressure sensor, ω...Control device, 100.
...Vacuum chamber agent Patent attorney Akio Takahashi (20 years old)

Claims (1)

[Claims] 1. A compressor that sucks working gas at room temperature and low pressure and discharges working gas at room temperature and high pressure; and an expansion means that adiabatically expands the working gas at room temperature and high pressure discharged from the compressor to generate cold; A cryopump is provided with a cryopanel attached to the expansion means to collect surrounding gas and capable of evacuating an object to be exhausted, the cryopump comprising: a power frequency converting means for a motor that drives the compressor; and a cryopanel for collecting surrounding gas. The apparatus includes a detection means for detecting temperature or pressure inside the exhaust object, and a control device that receives a signal from the detection means and controls the output frequency of the power supply frequency conversion means according to the temperature of the cryopanel or the pressure inside the exhaust object. A cryopump characterized by: