US 8,127,541 B2Granted

Working fluid cooling control system for construction machine

AssigneeHitachi Construction Machinery Co., Ltd.

InventorHidetoshi Satake

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Abstract

A working fluid cooling control system has a controller 100 that receives inputs 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.

Claims7

Dependent claims

A working fluid cooling control system for a construction machine having variable displacement type hydraulic pump, a plurality of members to be operated by said hydraulic pump, a heat exchanger for cooling a working fluid as an operating medium discharged from said hydraulic pump, a plurality of control valves for controlling respective flows of the working fluid delivered from said hydraulic pump to control the operation of the corresponding members to be operated, and a plurality of operation means provided for said plural control valves, respectively, the capacity of said hydraulic pump being increased depending on an increase in the operative amount of said plural operation means while the capacity of said hydraulic pump being decreased to a preset amount of a 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 increases the capacity of said hydraulic pump so as to increase an average flow rate of the working fluid passing through said heat exchanger when said first detection means detects the operation pattern corresponding to a rise in temperature of said working fluid,
said first detection means being configured to detect, as the operation pattern corresponding to a rise in temperature of the working fluid, at least one of two operation patterns, one being a first operation pattern such that an operation speed of one of said plural members to be operated having a higher frequency of heavy loading than at least one of the other members increases, and the other being a second operation pattern such that a particular operation mode is selected by a selector means among operation modes associated with said plural members to be operated, said particular operation mode providing a higher frequency of heavy loading than at least one of the other operation modes.

1 more element

A working fluid cooling control system for 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, a heat exchanger for cooling a working fluid as an operating medium discharged from said plural hydraulic pumps, a plurality of control valves for controlling respective flows of the working fluid delivered from said plural hydraulic pumps to control the operation of the corresponding members to be operated, and a plurality of operation means provided for said plural control valves, respectively, the capacities of said plural hydraulic pumps being increased depending on an increase in the operative amount of said plural operation means while the capacities of said plural hydraulic pumps being reduced to a preset amount of a minimum capacity when said plural members to be operated enter an unoperated state, characterized by further comprising:

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 increase the 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 when said first detection means detects the operation pattern corresponding to a rise in temperature of said working fluid,
said first detection means being configured to detect, as the operation pattern corresponding to a rise in temperature of the working fluid, at least one of two operation patterns, one being a first operation pattern such that an operation speed of one of said plural members to be operated having a higher frequency of heavy loading increases, and the other being a second operation pattern such that a particular operation mode is selected by a selector means among plural operation modes associated with said plural members to be operated, said particular operation mode providing a higher frequency of heavy loading,
said pump flow rate increasing means being configured to increase the capacity of the hydraulic pump used for the operation pattern detected by said first detection means among said plurality of pumps.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/064,930Filed 14 Sep 2006
Priority: JP 2005-27141220 Sep 2005
Published: US 2009/0148310 A111 Jun 2009
Granted: 6 Mar 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification17 codes

E02F 9/226
Hydraulic or pneumatic drives: safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
E02F 9/2292
Hydraulic circuits: systems with two or more pumps
E02F 9/2296
Hydraulic circuits: systems with a variable displacement pump
F15B 21/0423
Controlling the temperature of the fluid: cooling