Operation control device and method of vacuum pumps

Abstract

An operation control devices and operation methods thereof so as to eliminates the difficulties in such a case of introduction of vacuum sensors and / or inverter control is disclosed. The disclosure relates to a control of plural sets of vacuum pumps. In order to comply with the subjects to overcome the difficulties, the disclosure proposes to utilize current detection approach instead of direct pressure detection approach, while showing how to estimate a vacuum degree achieved under the operation of the pumps as well as presenting a method on the control of the number of pumps. It is also described how organically a current detecting device, a vacuum degree estimating device, a working pump control device and related methods to satisfy the subjects are linked. The usefulness of the disclosure is also revealed.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an operation-control device and an operation-control method of vacuum pumps such as a scroll pump, a vane pump and the like, especially to a case where plural set of vacuum pumps are provided.[0003]2. Description of the Related Art[0004]In conventional operation-control methods for vacuum pumps such as a scroll pump, a vane pump and the like, a frequency control by an inverter is introduced and the speed of an AC motor which drives a vacuum pump is controlled by using a signal of a pressure-sensor detecting a pressure of gas inside a vacuum tank to be depressurized. As for a pump load control by means of an inverter, a prior art, for instance, such as JP-A-H9-4591 / 1997 (hereafter, referred to as a patent document 1) has been known.[0005]As shown in FIG. 5, in the patent document 1 is illustrated a control-step constitution, wherein the speed of an AC motor 04, which drives a vacuum blowe...

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Benefits of technology

[0010]In view of the above-stated background, the present invention is aiming at: eliminating the difficulties in such a case of introduction of vacuum sensors and / or inverter speed control; realizing the operation of plural vacuum pumps wherein the increase of facility costs is restrained, the maintenance frequency is reduced and the man-hour of repair work is lessened; and providing an operation control device and an operation control method which are compatible with the just-stated aims.

[0011]In order to resolve the problems mentioned above, the present invention provides an operation control device of plural vacuum pumps for depressurizing a gas inside at least one tank and / or vacuum facility room and so on, including: a current detecting means which detects a current flowing in a motor that drives the vacuum pumps; and a control means which reduces the number of the vacuum pumps actually under operation, while judging whether a target vacuum or substantially vacuum condition is reached, based on a situation that a current value detected by the current detection means converges within a predetermined range.

[0012]According to the present invention, the current flowing in the motor is detected, and it is judged that a target vacuum or substantially target vacuum condition is realized when the current value converges within a predetermined range. Therefore, it is not necessary to provide with vacuum sensors for pressure detection of a vacuum tank as conventionally used, so that equipment costs can be restrained and a remarkable cost effectiveness can be obtained, especially in case where special sensors of a dust-free type and / or a waterproof type are required, depending on the service condition as to a vacuum tank or a vacuum facility room.

Problems solved by technology

Consequently, there arises a problem of cost increase as to equipment and / or facility.

Furthermore, a speed control inverter always accompanies electronic noise which causes undesirable problems to the surrounding electrical / electric equipment if it is nearby the inverter.

However, driving plural sets of pumps results in an increase of power consumption and maintenance costs.

Furthermore, providing plural pumps may increase failure frequency of the pumps, maintenance frequency of the pumps along with affiliated facility and man-hours for repairing.

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