Hydraulic excavator

Patent metadata

Field	Value
Publication number	US-9702119-B2
Application number	US-201414410832-A
Country	US
Kind code	B2
Filing date	Sep 5, 2014
Priority date	Sep 5, 2014
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

There is provided a hydraulic excavator in which the highly-accurate land leveling work is possible. A boom-lowering pilot conduit connected to a boom-lowering pilot port is provided with a boom-lowering proportional solenoid valve. When an arm dump signal for performing dump operation of an arm is included in a hydraulic pressure signal, a controller sharply increases a current value outputted to the boom-lowering proportional solenoid valve, as compared with when an arm excavation signal for performing excavation operation of the arm is included in the hydraulic pressure signal.

First claim

The invention claimed is:

1. A hydraulic excavator, comprising:
a work implement including a boom and an arm attached to said boom;
a pilot switching valve for said boom including a boom-lowering pilot port and controlling operation of said boom;
a boom-lowering pilot conduit connected to said boom-lowering pilot port;
a boom-lowering proportional solenoid valve provided in said boom-lowering pilot conduit;
an operation member for accepting user operation of driving said work implement and outputting a hydraulic pressure signal corresponding to said user operation; and
a controller for controlling an opening degree of said boom-lowering proportional solenoid valve, when an arm dump signal for performing dump operation of said arm is included in said hydraulic pressure signal, said controller sharply increasing a current value outputted to said boom-lowering proportional solenoid valve, as compared with when said controller outputs a current value to said boom-lowering proportional solenoid valve when an arm excavation signal for performing excavation operation of said arm is included in said hydraulic pressure signal.

2. The hydraulic excavator according to claim 1 , wherein
an amount of increase in current per unit time when said controller outputs, to said boom-lowering proportional solenoid valve, an instruction signal for instructing an increase in opening degree is larger when said arm dump signal is included in said hydraulic pressure signal than when said arm excavation signal is included in said hydraulic pressure signal.

3. The hydraulic excavator according to claim 1 , wherein
when said arm dump signal is included in said hydraulic pressure signal, said controller increases, in a step manner, the current value outputted to said boom-lowering proportional solenoid valve.

4. The hydraulic excavator according to claim 1 , wherein
said work implement further includes a bucket attached to said arm and having a cutting edge, and
said controller controls said boom to prevent said cutting edge from becoming lower than a design topography indicating a target shape of a work object.

5. The hydraulic excavator according to claim 1 , wherein
said controller transmits and receives information by satellite communication.

6. The hydraulic excavator according to claim 2 , wherein
when said arm dump signal is included in said hydraulic pressure signal, said controller increases, in a step manner, the current value outputted to said boom-lowering proportional solenoid valve.

7. The hydraulic excavator according to claim 2 , wherein
said work implement further includes a bucket attached to said arm and having a cutting edge, and
said controller controls said boom to prevent said cutting edge from becoming lower than a design topography indicating a target shape of a work object.

8. The hydraulic excavator according to claim 2 , wherein
said controller transmits and receives information to and from the outside by satellite communication.

Assignees

• Komatsu Mfg Co Ltd

Inventors

• Matsuyama Toru
• Takaura Takeshi

Classifications

• E02F9/262

  with follow-up actions to control the work tool, e.g. controller · CPC title

• E02F9/2207

  for reducing or compensating oscillations · CPC title

• E02F9/2228 Primary

  including an electronic controller · CPC title

• E02F3/437 Primary

  providing automatic sequences of movements, e.g. linear excavation, keeping dipper angle constant · CPC title

• E02F9/2292

  Systems with two or more pumps · CPC title