WORKING FLUID COOLING CONTROL SYSTEM FOR CONSTRUCTION MACHINE
First Claim
1. A working fluid cooling control system for a construction machine having variable displacement type hydraulic pumps, a plurality of members to be operated by said hydraulic pump, and a heat exchanger for cooling a working fluid as an operating medium, the capacity of said hydraulic pump being decreased to a preset minimum capacity when said plural members to be operated enter an unoperated state, wherein the working fluid cooling control system comprises:
- first detection means for detecting an operation pattern corresponding to a rise in temperature of said working fluid from among operation patterns associated with said plural members to be operated; and
pump flow rate increasing means which on the basis of the operation pattern detected by said first detection means increase the minimum capacity of said hydraulic pump so as to increase an average flow rate of the working fluid passing through said heat exchanger.
1 Assignment
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Accused Products
Abstract
A working fluid cooling control system has a controller 100 that receives input signals from a traveling motor speed pickup 101, a pressure sensor 102, a signal receiving line 103a of an option selecting switch 103 and a temperature sensor 104. The controller performs predetermined arithmetic processing and controls proportional solenoid valves 105 and 106. The pressures controlled by the solenoid valves are compared with positive control command pressures in shuttle valves 109 and 110. In this way, in the case of an operation pattern corresponding to a rise in temperature of the working fluid, minimum tilting angles of hydraulic pumps 11 and 12 are increased to increase an average flow rate of the working fluid passing through an oil cooler 40, thereby increasing an average heat discharge amount and reducing an equilibrium temperature of the working fluid.
6 Citations
10 Claims
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1. A working fluid cooling control system for a construction machine having variable displacement type hydraulic pumps, a plurality of members to be operated by said hydraulic pump, and a heat exchanger for cooling a working fluid as an operating medium, the capacity of said hydraulic pump being decreased to a preset minimum capacity when said plural members to be operated enter an unoperated state, wherein the working fluid cooling control system comprises:
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first detection means for detecting an operation pattern corresponding to a rise in temperature of said working fluid from among operation patterns associated with said plural members to be operated; and pump flow rate increasing means which on the basis of the operation pattern detected by said first detection means increase the minimum capacity of said hydraulic pump so as to increase an average flow rate of the working fluid passing through said heat exchanger. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A construction machine comprising a plurality of variable displacement type hydraulic pumps, a plurality of members to be operated by each of said plural hydraulic pumps, and a heat exchanger for cooling a working fluid as an operating medium, the capacities of said plural hydraulic pumps being reduced to a preset minimum capacity when said plural members to be operated enter an unoperated state, characterized by further comprising:
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first detection means for detecting an operation pattern corresponding to a rise in temperature of said working fluid from among operation patterns associated with said plural members to be operated; and pump flow rate increasing means which on the basis of the operation pattern detected by said first detection means increase the minimum capacity of at least one of said plural hydraulic pumps to increase an average flow rate of the working fluid passing through said heat exchanger. - View Dependent Claims (10)
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Specification