Elevator system monitoring cold oil

An elevator system in a structure, with the elevator being adapted to be hydraulically driven with prewarmed hydraulic oil obtained by operationally recirculating the cold oil in a reservoir, the oil otherwise being available for driving an in-service elevator car in the structure, said system comprising:

• motor drive means having an output shaft for providing an output torque when said motor drive means is energized;
• pump means coupled to the output shaft of said motor drive means for drawing through its intake the available hydraulic oil from the oil reservoir and being adapted to expel pressurized oil from its output;
• hydraulic jack means having an oil input and output and a fluid chamber therebetween adapted to move the elevator car upwardly and downwardly to serve floors in the structure;
• valve means including up and down control valves connected between the output of said pump means and the input of said hydraulic jack means, and said valve means being capable of returning oil to the reservoir;
• thermostat means responsive to the temperature of hdyraulic oil for signaling a cold oil condition when the temperature of the oil is below an operating standard;
• and
• control means responsive to the cold oil temperature signal from said thermostat means to activate the operation of said pump means through energization of said motor drive means for pumping oil through said operational valve means to recirculate the oil from one portion of the reservoir through the valve means;
• said control means including a program module which interacts with the cold oil signal from said thermostat which serves as an input to begin a minimum timer counting phase for a sequence of timing counts throughout which time counts and program sequencing of said pump is activated through energization of said motor drive means to warm the temperature of oil in the direction of reaching the temperature minimum by bypassing said hydraulic jack means, and return the oil to another portion of the reservoir during a predetermined sequence of timing counts so that the temperature of the recirculating oil is warmed up to the temperature minimum for elevator operation.

A method of operating a hydraulic elevtor system in a structure, with the elevator being adapted to be driven by a hydraulic jack with prewarmed hydraulic oil obtained by operationally recirculating the cold oil in a reservoir, the oil otherwise being available for driving an in-service elevator car in the structure, said method comprising the steps of:

• providing motor drive means having an output shaft for producing an output torque when said motor drive means is energized;
• providing pump means rotationally coupled to the output shaft of said motor drive means for drawing through its intake the available hydraulic oil from the oil reservoir and expelling pressurized oil from its output after a vertical rise;
• providing valve means including up and down control valves connected between the output of said pump means and the input of said hydraulic jack, and said valve means returning oil to the reservoir;
• providing thermostat means responsive to the temperature of hydraulic oil for signaling a cold oil condition when the temperature of the oil is below an operating standard;
• and
• providing control means interacting through control programming reponsive to the cold oil temperature signal from said thermostat means to activate the operation of said pump means for a time interval of a minimum program timer by energizing said motor drive means for pumping oil through said operational valve means to recirculate the oil from one portion of the reservoir through the valve means, bypassing said hydraulic jack means, and return the oil to another portion of the reservoir during a predetermined sequence of timing counts so that the temperature of the recirculating oil is warmed up to the temperature minimum for elevator operation.