CN2262615Y

CN2262615Y - Speed-regulating mechanical vacuum pump

Info

Publication number: CN2262615Y
Application number: CN 95241145
Authority: CN
Inventors: 刘文兴
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-12-22
Filing date: 1995-12-22
Publication date: 1997-09-17
Anticipated expiration: 2005-12-22

Abstract

The utility model relates to a speed-regulating mechanical vacuum pump. The utility model is used for extracting gases to establish and keep vacuum state. The utility model is composed of a pump body, an electric motor which is connected with the pump body, and an electrical control box which is connected with the electric motor. The power supply main circuit of the interior of the electrical control box comprises an alternating current contactor 2 and an automatic air switch 1 which are orderly connected with the electric motor 6 in series. The utility model is characterized in that an alternating current frequency-changing transformer is connected between the alternating current contactor 2 and the electric motor 6 in series; the frequency-changing transformer is composed of a rectifying circuit 3, a middle direct current circuit 4 and an inverter circuit 5 which are connected in series. The utility model conveniently and largely regulates the speed in operation. Compared with the common mechanical vacuum pump, the volume is small, and the rated power of the electric motor is low.

Description

The speed governing oil-sealed rotary pump

The utility model relates to and a kind ofly extracts in the seal container gas to obtain the oil-sealed rotary pump of vacuum with mechanical means.

For the place that requires vacuum or negative pressure, all to use the vacuum pump extracting gases to set up and keep vacuum or negative pressure state.What it was the most frequently used is oil-sealed rotary pump.As water-ring pump, reciprocating pump, oil sealing mechanical pump, Roots pump etc.During the mechanical vacuum pump work, be the vacuum or the establishment stage of high vacuum more at the beginning.At this moment, because pump intake place air pressure is higher, degree of vacuum is lower, so the power maximum that needs of vacuum pump at this moment.Along with the startup of pump, gas is extracted out gradually, and the air pressure at pump intake place is more and more lower, and the pump desired power is also just more and more lower.Through the operation of certain hour, the air pressure at pump intake place is gradually stable, and the pump desired power also tends towards stability.Because the vacuum establishment stage is an of short duration process, vacuum set up process the deficiency of time maintenance stage 5%.Oil-sealed rotary pump and other mechanical pump, blower fan are different in other words, and the most of the time is to move at low power state rather than under high power state.And when the rotating speed of pump increased, the power that oil-sealed rotary pump needs was not directly proportional with the cube of rotating speed as other mechanical pump, blower fan yet, and just is directly proportional with the first power of rotating speed.So in the vacuum maintenance stage, the power that oil-sealed rotary pump needs has only 1/5～1/3 when starting.As at this moment improving its rotating speed, both having made is to be doubled and redoubled, and can not exceed the power of needs when starting, and at this moment the pumping speed of pump but can increase closely exponentially.But therefore present oil-sealed rotary pump can only also just can not utilize these characteristics of oil-sealed rotary pump with almost constant rotating speed operation.

The purpose of this utility model is to provide a kind of speed governing oil-sealed rotary pump that can change the oil-sealed rotary pump pumping speed on demand.

The utility model is to realize like this, a kind of speed governing oil-sealed rotary pump, its mechanical pump housing is identical with the mechanical pump housing of common oil-sealed rotary pump, and in the electric control box of common oil-sealed rotary pump, behind the A.C. contactor of vacuum machine pump motor power supply, be serially connected with a variable-frequency transformer, such electric control box according to its volume size, can be installed on the support, also can be installed separately with support, the centre is connected control box and motor with lead.Therefore the power supply main circuit of such electric control box just becomes automatic air-break switch, A.C. contactor and the variable-frequency transformer that order is connected in series, and this variable-frequency transformer is made up of rectification circuit, intermediate DC circuit and the inverter circuit of series connection successively.Rectification circuit can be transformed to the industrial-frequency alternating current that is transmitted by A.C. contactor the direct current of pulsation; Intermediate DC circuit is carried out the direct current of pulsation filtering and is stored idle; Inverter circuit becomes filtered dc inverter from being lower than power frequency to the different frequency more much higher than power frequency, the Ac of different voltages.Such mechanical vacuum pump motor is accepted just is not the single-frequency that transmits from A.C. contactor, the industrial-frequency alternating current of single voltage, but the arbitrary frequency that is transformed into as required through variable-frequency transformer and the Ac of voltage, the rotating speed of motor and output torque also just change along with the change of the frequency of variable-frequency transformer output and voltage, rotating speed by motor-operated vacuum pump also just changes, and the pumping speed of pump has also just obtained adjusting.

Compare with the existing mechanical vacuum pump, the utility model is owing to increased by one by rectification circuit in the power supply main circuit of electric control box, the AC frequency conversion transformer that intermediate DC circuit and inverter circuit are formed, when starting, can power to motor with lower electric frequency, make the rotating speed of motor and pump lower, can reduce the rated power of motor, behind the pump startup, along with the air pressure at pump intake place and the power of pump actual consumption descend, progressively improve frequency of supply, the rotating speed of motor and pump is improved constantly, and the comparable power frequency of this electric frequency is much higher, to satisfy usage requirement.Like this it on-stream can be easily, speed governing significantly, when normal operation, can use different speed operation much higher when starting on demand.Therefore under identical pumping speed, this pump is littler than the volume of common oil-sealed rotary pump, and the rated power of the motor of adapted is lower.

Fig. 1 is the power supply main circuit schematic representation of electric control box of the present utility model.

Below in conjunction with accompanying drawing mode of execution of the present utility model being done one describes in detail:

As shown in Figure 1, the utility model is made up of with the electric control box that is connected with motor the mechanical pump housing, the motor 6 that connects the pump housing, and the pump housing is identical with common oil-sealed rotary pump.The power supply main circuit of electric control box is automatic air-break switch 1, A.C. contactor 2 that is connected in series successively and the AC frequency conversion transformer of being made up of rectification circuit 3, intermediate DC circuit 4, inverter circuit 5.6 for dragging the vacuum pump motor.This electric control box and support partial installation, the middle lead of using is connected with pump motor.Wherein automatic air-break switch 1 do whole circuit protection and when maintenance electrical isolation use; The connecting and disconnecting circuit was used when A.C. contactor was done operation; Rectification circuit 3 in the AC frequency conversion transformer is with the direct current of industrial frequency AC electric rectification for pulsation; Intermediate DC circuit 4 plays the energy storage effect of reactive energy simultaneously with the direct current filtering after the rectification; Inverter circuit 5 can be the Ac of different frequency and voltage with the inversion on demand of filtered direct current, is used for drive motor 6.Motor 6 drives pump 7 and rotates.Like this, just can supply with the frequency and the voltage of the electric current of motor 6, adjust the rotating speed of motor, thereby realize the speed governing of oil-sealed rotary pump by changing inverter circuit 5 on demand.When starting, with lower electric frequency starting, the pumping speed of pump is lower, and the power that needs is also less, along with the reduction of pump intake place air pressure, progressively improve electric frequency, the rotating speed of pump and pumping speed are increased, the electricity frequency can be transferred to more much higher than power frequency, and therefore, the pumping speed of pump also can be much higher when starting.

Claims

1, a kind of extracting gases that is used for is to set up and to keep the speed governing oil-sealed rotary pump of vacuum state, motor by the pump housing, the connection pump housing is formed with the electric control box that is connected with motor, be provided with a power supply main circuit in the described electric control box, this power supply main circuit comprises A.C. contactor (2) and the automatic air-break switch (1) that is connected in series successively with motor (6), it is characterized in that being connected in series an AC frequency conversion transformer between A.C. contactor (2) and motor (6).

2, a kind of speed governing oil-sealed rotary pump according to claim 1 is characterized in that the AC frequency conversion transformer is made up of the rectification circuit that is connected in series successively (3), intermediate DC circuit (4) and inverter circuit (5).