Patent ID: 8051649
Filing Date: 2011-11-08
Classification: E02F,F15B,Y02P

Abstract:
1. In a hydraulically driven industrial machine having a variable displacement type hydraulic pump operative to take in and pressurize working oil from a working oil tank, and a hydraulic actuator supplied with discharge oil of said hydraulic pump through a control valve to perform a predetermined job: a variable return oil cooling means capable of cooling down return oil from said hydraulic actuator at a variable cooling rate to control a working oil temperature to a given level; an operational load detection means adapted to detect operational load conditions of said hydraulic actuator; and a control means adapted to measure an operational load factor of said hydraulic actuator within a predetermined unit time period of detection cycle to get a mean value of said load factor as a past record of operational load data, and to determine and set a cooling rate of return oil from said hydraulic actuator on the basis of said past record of working load data.