초록 ▼

A speed command signal is applied to a variable voltage, variable frequency controller for driving a three-phase induction motor that operates a positive displacement pump for supplying fluid to a hydraulic elevator drive cylinder. An accelerometer mounted on the car provides an acceleration-related

A speed command signal is applied to a variable voltage, variable frequency controller for driving a three-phase induction motor that operates a positive displacement pump for supplying fluid to a hydraulic elevator drive cylinder. An accelerometer mounted on the car provides an acceleration-related feedback signal to the car speed command input of the motor control, thereby to dampen low frequency resonant modes of the elevator car. A sensor on a check valve between the hydraulic pump and the hydraulic cylinder provides a signal indicative of when the pump pressure is sufficient to support the car load, and the check valve begins to open; the signal is used to memorize ramped-up motor speed at that point, which equals the motor speed necessary to overcome pump leakage in order to support the car. That speed is added into the car speed command at the input of the motor controller to compensate for pump leakage. The acceleration damping of low frequency resonant modes of the elevator car may be utilized in roped elevator systems.

대표청구항 ▼

An hydraulic elevator system, comprising: an elevator car disposed in a hoistway to serve a plurality of floors in a building; an hydraulic hoist cylinder connected to said elevator car for vertically positioning said car in said hoistway; a positive displacement rotary pump for providing hydraulic

An hydraulic elevator system, comprising: an elevator car disposed in a hoistway to serve a plurality of floors in a building; an hydraulic hoist cylinder connected to said elevator car for vertically positioning said car in said hoistway; a positive displacement rotary pump for providing hydraulic fluid to said cylinder; a check valve disposed between said pump and said cylinder, said check valve preventing reverse flow of hydraulic fluid from said cylinder when said cylinder is holding said car stationary at a floor landing, said check valve having a sensor for providing a check valve signal indicative of said check valve beginning to open after pressure of fluid provided by said pump is equal to the pressure of fluid on the cylinder side of said check valve; an electric motor for driving said pump; a motor speed sensor disposed on said motor to provide a motor speed signal indicative of the rotary speed of said motor; a controller responsive to said check valve signal for providing a motor speed command signal to effect a car speed profile after said check valve signal indicates said check valve is opening; and a motor speed control responsive to said motor speed sensor and to said controller for causing said motor to operate at a rotary speed determined by said motor speed command signal; characterized by the improvement comprising: said controller, when said car is to run, providing a continuously increasing pump leakage speed command signal until said check valve signal indicates that said check valve has begun to open, and thereafter providing a constant pump leakage speed command signal equal to the value thereof when said check valve began to open, said controller being also responsive to said pump leakage speed command signal to provide said motor speed command signal in response thereto, whereby to ramp up said motor speed to the point where the check valve opens and thereafter to compensate for leakage in said pump.