Construction machine

• US 6,148,548 A
• Filed: 06/29/1999
• Issued: 11/21/2000
• Est. Priority Date: 06/30/1998
• Status: Expired due to Fees

• Current Assignee: Klaus Schmidt
• Original Assignee: Klaus Schmidt
• Inventors: Tohji, Yutaka
• Primary Examiner(s): BATSON, VICTOR D
• Application Number:
  US09/342,265
• Time in Patent Office: 511 Days
• Field of Search: 37/348, 37/382, 37/347, 37/381, 37/902, 172/2, 172/3, 172/4, 172/4.5, 172/8, 701/50, 60/421, 60/422, 60/420, 60/428, 60/429, 60/430, 60/443
• US Class Current: 37/348
• CPC Class Codes: E02F 9/2242 including an electronic controller
• CPC Class Codes: E02F 9/2282 Systems using center bypass type changeover valves
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump

Abstract

A construction machine comprising two hydraulic pumps; right and left traveling motors for causing the construction machine to travel; work machine actuators for actuating a work machine of the construction machine; a control valve which makes control so that a hydraulic oil discharged from the two hydraulic pumps is fed to at least either the right and left traveling motors or the work machine actuators and so that when both traveling operation and work machine operation are performed simultaneously, the hydraulic oil discharged from one of the two hydraulic pumps is fed to the traveling motors and the hydraulic oil from the other hydraulic pump is fed to the work machine actuators, the control valve providing communication between the two hydraulic pumps through a pump communication path; a drive signal detecting device which detects drive signals with respect to the two hydraulic pumps when the traveling operation and the work machine operation are performed simultaneously; and a controller which controls the controls valve so as to throttle or close the pump communication path in accordance with the drive signals detected by the drive signal detecting device. According to this construction machine, pressure interference is not likely to occur between the two hydraulic pumps, nor is it likely that oil may flow from a high pressure side to a low pressure side, causing the high pressure side to become inoperative and the low pressure side to become accelerated.

Claims

1. A construction machine comprising:

two hydraulic pumps;

right and left traveling motors for causing the construction machine to travel;

work machine actuators for actuating a work machine of the construction machine;

a control valve which makes control so that a hydraulic oil discharged from said two hydraulic pumps is fed to at least either said right and left traveling motors or said work machine actuators and so that when a traveling operation and a work machine operation are performed simultaneously, the hydraulic oil discharged from one of said two hydraulic pumps is fed to said traveling motors and the hydraulic oil from the other hydraulic pump is fed to said work machine actuators, said control valve providing communication between said two hydraulic pumps through a pump communication path;

drive signal detecting means which detects drive signals with respect to said two hydraulic pumps when the traveling operation and the work machine operation are performed simultaneously; and

a controller which controls said control valve so as to throttle or close said pump communication path in accordance with the drive signals detected by said drive signal detecting means.

2. A construction machine according to claim 1, wherein said controller compares the drive signals detected by said drive signal detecting means and throttles or closes said pump communication path when the difference in magnitude between the drive signals is larger than a predetermined value.

3. A construction machine according to claim 1, wherein said controller compares the drive signals detected by said drive signal detecting means and throttles or closes said pump communication path when the magnitude of one of the drive signals is larger than a predetermined value.

4. A construction machine according to claim 1, wherein said drive signal detecting means is attached to each of said two hydraulic pumps.

5. A construction machine according to claim 1, wherein said drive signal detecting means is attached to each of said traveling motors and said work machine actuators.

6. A construction machine with two hydraulic pumps mounted thereon and wherein at the time of a traveling operation said two hydraulic pumps drive right and left traveling motors respectively, while when a traveling operation and a work machine operation are performed simultaneously, the traveling motors are driven by one of said hydraulic pumps and work machine actuators are driven by the other hydraulic pump, said two hydraulic pumps being in communication with each other, characterized by including:

drive signal detecting means for detecting drive signals with respect to said two hydraulic pumps when both said traveling operation and work machine operation are performed simultaneously; and

communication path control means which throttles or closes a communication path between said two hydraulic pumps in accordance with the drive signals detected by said drive signal detecting means.