WORKING FLUID COOLING CONTROL SYSTEM FOR CONSTRUCTION MACHINE

• US 20090148310A1
• Filed: 09/14/2006
• Published: 06/11/2009
• Est. Priority Date: 09/20/2005
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Satake, Hidetoshi
• Granted Patent: US 8,127,541 B2
• Time in Patent Office: Days
• US Class Current: 417/228
• CPC Class Codes: E02F 9/226 Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 21/0423 Cooling
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/30595 with additional valves between the groups of valves for multiple output members
• CPC Class Codes: F15B 2211/62 Cooling or heating means
• CPC Class Codes: F15B 2211/6336 representing a state of the output member, e.g. position, speed or acceleration
• CPC Class Codes: F15B 2211/6343 representing a temperature
• CPC Class Codes: F15B 2211/6346 representing a state of input means, e.g. joystick position
• CPC Class Codes: F15B 2211/6652 Control of the pressure source, e.g. control of the swash plate angle
• CPC Class Codes: F15B 2211/6658 Control using different modes, e.g. four-quadrant-operation, working mode and transportation mode
• CPC Class Codes: F15B 2211/7135 Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
• CPC Class Codes: F15B 2211/85 Control during special operating conditions

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.

Claims

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.

2. The working fluid cooling control system for a construction machine according to claim 1, wherein said first detection means detect, as the operation pattern corresponding to a rise in temperature of the working fluid, operation states of members with higher loading frequency out of said plural members to be operated.

3. The working fluid cooling control system for a construction machine according to claim 2, wherein said first detection means detects, as the operation state of said member with higher loading frequency, an operation signal of operation means for said member.

4. The working fluid cooling control system for a construction machine according to claim 2, wherein said first detection means detects, as the operation state of said member with higher loading frequency, an operation speed of said member.

5. The working fluid cooling control system for a construction machine according to claim 1, wherein said first detection means detects, as the operation pattern corresponding to a rise in temperature of said working fluid, an operation mode with higher loading frequency from among operation modes associated with said plural members to be operated.

6. The working fluid cooling control system for a construction machine according to claim 5, wherein:

said construction machine further has selector means for selecting an operation mode using an attachment such as a crusher or the like and other operation modes, and

said first detection means detects said operation mode using a crusher as said operation mode with higher loading frequency.

7. The working fluid cooling control system for a construction machine according to claim 1, wherein the working fluid cooling control system for a construction machine further comprises second detection means for detecting a temperature of said working fluid, and

wherein said pump flow rate increasing means increase the minimum capacities of said hydraulic pumps on the basis of both the operation pattern detected by said first detection means and the temperature of the working fluid detected by said second detection means.

8. The working fluid cooling control system for a construction machine according to claim 7, wherein said pump flow rate increasing means comprise:

means for calculating a first minimum capacity on the basis of the operation pattern detected by said first detection means;

means for calculating a second minimum capacity on the basis of the temperature of the working fluid detected by said second detection means;

means for selecting the larger capacity of said first and second minimum capacities; and

means for changing the minimum capacities of said hydraulic pumps on the basis of the selected minimum capacity.

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:

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.

10. The construction machine according to claim 9, wherein:

said first detection means detect, as the operation pattern corresponding to a rise in temperature of said working fluid, an operation pattern associated with a first to-be-operated member operated by one hydraulic pump out of said plural hydraulic pumps, and

said pump flow rate increasing means increase the minimum capacity of the other hydraulic pump than said one hydraulic pump on the basis of the operation pattern associated with said first to-be-operated member.