JPH03107599A - Control system of axial-flow pump device - Google Patents

Abstract

PURPOSE:To control the entire body of an axial-flow pump device in an optimum condition by accurately detecting a suction force condition of the axial- flow pump, and by controlling the driving and stopping of the axial-flow pump, as well as the opening/closing of inlet/exhaust valves, and so on, based on the detected information. CONSTITUTION:In a turbo-molecular pump 2 as an axial-flow pump, a pump load detector 5 is mounted. Based on a detection signal from the pump load detector 5, through a controller 6 of the turbo-molecular pump 2 as well as main controller 7 of an axial-flow pump device, a valve 1 on the suction force side and a valve 3 on the exhaust force side are controlled, respectively. When the ultra vacuum pressure exceeds, for example, a set value, the turbo-molecular pump 2 is temporarily stopped by the controller 6, and the valve 1 on the suction force side is closed. So as to meet the ultra vacuum condition controlled by the controller 6, a front stage pump 4 is controlled by the main controller 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control system for an axial flow pump device including an axial flow pump and its peripheral devices.

C. Prior Art] Turbomolecular pumps are generally used as axial flow pumps, especially pumps that generate ultra-high vacuum pressure.

This turbo-molecular pump has a structure similar to that of an axial flow turbine, in which a rotor with a constant inclination and a stator with an inclination opposite to the rotor are alternately stacked in multiple stages to rotate the rotor blades at high speed. Creates an ultra-vacuum by obtaining exhaust action.

Turbomolecular pumps suck gases such as nitrogen, hydrogen, helium, etc., and generally operate at a pressure of 10 to 10" Torr.
A degree of ultra-vacuum can be obtained. However, since the vacuum pressure obtained with a turbo-molecular pump is extremely low, a pre-stage pump is generally installed on the exhaust side of the turbo-molecular pump to discharge the exhaust gas to atmospheric pressure. An intake pressure side valve, an exhaust pressure side valve, etc. are provided between the turbomolecular pump and the pre-stage pump to control the exhaust.

When axial flow pumps such as the turbomolecular pumps and pre-stage pumps mentioned above are operated in a low vacuum environment with a large gas flow rate, the large load can cause the temperature of the rotor blades to rise or the axis of rotation to shift, causing damage to the pump. Therefore, it is necessary to operate the pump below the maximum suction pressure and maximum exhaust pressure allowed for the pump.

Conventionally, in order to operate an axial flow pump safely, the intake pressure and exhaust pressure of the axial flow pump have been controlled using a vacuum gauge placed outside the pump.

[Problem to be solved by the invention]

However, the vacuum gauge for detecting the vacuum pressure of an axial flow pump such as the above-mentioned turbo-molecular pump has to be a special and expensive one that can withstand extremely low pressure because the pressure is ultra-vacuum.

Furthermore, the information on the pump load state obtained from the vacuum gauge is used only for the operation of the turbo-molecular pump, and cannot be directly used for safely operating the peripheral devices of the turbo-molecular pump.

This invention was made in view of the current state of technology for detecting the operating status of conventional axial flow pumps as described above, and its purpose is to detect the rotor rotational speed of an axial flow pump without using an expensive vacuum gauge. , the vacuum pressure is determined from the axial flow pump drive status measured by a detector that detects either the motor drive current, the rotational drive torque of the rotor, or a combination of some of these, and from that information, it is possible to detect not only the axial flow pump but also the axial flow pump. It is an object of the present invention to provide a control system that can optimally control a device as a whole including its peripheral devices.

[Means to solve the problem]

Therefore, in this invention, as a means to solve the above problem, for an axial flow pump device including an intake pressure side valve, an axial flow pump, an exhaust pressure side valve, a pre-stage pump, etc., the rotor rotation speed and motor drive are set at appropriate positions of the axial flow pump. A detector that detects either current or rotor blade rotation torque, or a combination of several of them, is provided, and a signal from this detector is sent to the controller of the axial flow pump device, and the control signal is used to detect the area around the axial flow pump. The configuration of the control system for an axial flow pump device was adopted to control the device.

[Effect]

In the control system according to the present invention configured as described above, the operating state of the axial flow pump and the suction pressure (ultra vacuum pressure) can be accurately detected by any one of the above-mentioned detectors or a combination of some of them, and the information thereof can be accurately detected. is converted into an electrical signal and sent to the controller.

The controller starts the axial flow pump based on the above information,
In addition to controlling the stoppage, it also controls peripheral equipment such as valves and pre-stage pumps, thereby driving and controlling the entire axial flow pump device to an optimal operating state. Therefore, it is not necessary to measure pressure using an expensive vacuum gauge, and moreover, it is possible to measure pressure with higher accuracy.
Control is possible.

〔Example〕

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

FIG. 1 is an overall schematic block diagram of the axial flow pump device of this embodiment. 01 is a process chamber.

1 is an intake pressure side valve, 2 is a turbo molecular pump which is a type of axial flow pump, 3 is an exhaust pressure side valve, and 4 is a front stage pump.

Each valve is a control valve. As mentioned above, a turbomolecular pump uses a rotor whose blades have a certain inclination and a stator whose blades are oriented in the opposite direction, which are alternately stacked in multiple stages to rotate the rotor blades at high speed and obtain ultra-vacuum pressure. .

The pre-stage pump 4 is a pump for suctioning the exhaust pressure of the turbo-molecular pump 2 to atmospheric pressure, since it is difficult to exhaust from ultra-vacuum to atmospheric pressure with the turbo-molecular pump 2, for example. Conventional hydraulically driven axial flow pumps are commonly used.

5 is a pump load detector installed in the turbo molecular pump. As this detector 5, for example, a rotation speed detector such as a rotor encoder that detects the rotor rotation speed can be used. Alternatively, a motor drive current detector or a rotary torque meter of the rotor blade rotating shaft may be used.

The detector 5 can know the pump load condition in advance from its characteristic curve according to each type, so it can convert the load condition into an electrical signal and output it to the outside as information. It is set in.

The signal from the detector 5 is given to the controller 6 of the turbomolecular pump, and the signal is also sent to the main controller 7 of the axial flow pump device. And the controller 6
In order to control the intake pressure side valve 1 and the exhaust pressure side valve 3 to the required operating states using control signals from the main controller 7, a control circuit as shown in the figure is provided to send control signals to the respective valves. .

The axial flow pump device of this embodiment configured as described above is
When the turbo molecular pump 2 is started, the process chamber 01 is sucked and the inside thereof is brought to ultra-vacuum pressure. The ultra-vacuum pressure state is determined by one of the types of the detector 5 described above to determine the pump load, and the detector 5 sends an electric signal converted into ultra-vacuum pressure information based on the load state to the controller 6.

Information on the pump load state based on the type of the detector 5 can be obtained, for example, from the performance curve shown in FIG.

According to this, in general, as the pump load increases, the rotor rotational speed decreases, and the motor drive current and rotor blade drive torque increase as the pump load increases.

Therefore, if the controller 6 is provided with a storage section that stores any of the performance curves corresponding to the type of the detector as analog data or digital data, the load state can be easily determined.

Note that even more accurate information can be obtained by calculating the pump load state by combining several types of detectors 5.

Based on the ultra-vacuum pressure information sent to the controller 6, the controller 6 temporarily stops the turbo molecular pump 2 and closes the intake pressure side valve 1 when the ultra-vacuum pressure exceeds a predetermined value. A predetermined vacuum pressure is maintained, and when the ultra-vacuum pressure falls below a predetermined value, the turbo molecular pump 2 is activated again and a control signal is output so as to bring the ultra-vacuum pressure closer to the predetermined ultra-vacuum pressure.

In response to the control by the controller 6, the main controller 7 gives commands to the pre-stage pump to adapt to the ultra-vacuum state according to the control signal, thereby monitoring and controlling the operating state of the entire apparatus.

〔effect〕

As explained in detail above, in the present invention, the suction pressure state of the pump is accurately detected by a detector that detects any one or a combination of the rotor rotation speed, motor drive current, and rotor blade rotation torque of the pump. Based on this information, the controller controls peripheral equipment such as driving and stopping the axial flow pump, as well as opening and closing the intake and exhaust valves, so it is no longer possible to measure ultra-vacuum pressure using an expensive vacuum gauge as in the past. There is no need to measure, economical and accurate measurements can be made, and the entire axial flow pump device can be controlled in an optimal state based on the information.

[Brief explanation of drawings]

FIG. 1 is a general schematic system diagram of an axial flow pump device according to the present invention, and FIG. 2 is a graph showing different performance curves for each type of detector with respect to pump load. 01... Process chamber, 1... Intake pressure side valve, 2... Turbo molecular pump, 3... Exhaust pressure side valve, 4... Pre-stage pump, 5...Detector, 6...
- Controller, 7... Main controller.

Claims (1)

[Claims] (1) Intake pressure side valve, axial flow pump, exhaust pressure side valve,
For axial flow pump devices including front-stage pumps, etc., a detector for detecting either rotor rotation speed, motor drive current, or rotor blade rotation torque, or a combination of these, is installed at an appropriate position on the axial flow pump. A control system for an axial flow pump device that sends a signal from this detector to a controller of the axial flow pump device, and controls devices around the axial flow pump using the control signal.