Electricity: motive power systems – With particular motor-driven load device – Power- or motion-transmitting mechanism
Patent
1987-11-20
1988-12-27
Ro, Bentsu
Electricity: motive power systems
With particular motor-driven load device
Power- or motion-transmitting mechanism
318286, 318466, 25112913, F16K 3104
Patent
active
047943092
ABSTRACT:
An electric actuator for a control valve for fluids utilizes an induction motor to control the degree of opening of the valve and is provided with a control system which determines the deviation of the actual opening degree from the demand opening degree, generates a valve opening or closing speed command in accordance with the opening deviation, determines the deviation of the actual opening or closing speed from the command speed, generates a torque command in accordance with the speed deviation, and computes by means of the vector computing method the primary current to be supplied to the induction motor to enable the induction motor to output the required torque. When the valve is in the fully closed position, the control system stops the supply current to the induction motor and activates a braking device which locks the motor shaft to prevent reverse rotation of the motor shaft due to load reaction. The actuator has a means for re-starting the induction motor to optimize the thrust load should any change occur in the level of thrust acting on the valve rod. The actuator is furthermore provided with a means for diagnosing whether any abnormal performance is due to wear and/or deterioration of the induction motor, of the torque transmitting system or of the valve body.
REFERENCES:
patent: 3700085 (1972-10-01), Balz
patent: 4364111 (1982-12-01), Jocz
patent: 4445075 (1984-04-01), Fry
patent: 4452423 (1984-06-01), Beblavi et al.
patent: 4456865 (1984-06-01), Robertson et al.
patent: 4556832 (1985-12-01), Rollins
Endo Toshio
Saito Takeshi
Suguro Takeshi
Utsumi Yutaka
Bailey Japan Co., Ltd.
Nippon Gear Co., Ltd.
Ro Bentsu
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