Hydraulic drive system of construction machine

Patent metadata

Field	Value
Publication number	US-2016251833-A1
Application number	US-201415028825-A
Country	US
Kind code	A1
Filing date	Oct 10, 2014
Priority date	Oct 31, 2013
Publication date	Sep 1, 2016
Grant date	—

Abstract

A hydraulic drive system of a construction machine includes: a first hydraulic pump and a second hydraulic pump, whose respective tilting angles are adjustable independently of each other; a turning control valve for controlling supply of hydraulic oil to a turning motor; and a boom main control valve and a boom auxiliary control valve each for controlling supply of the hydraulic oil to a boom cylinder. The turning control valve and the boom auxiliary control valve are disposed on a first bleed line, and the boom main control valve is disposed on a second bleed line. A turning operation valve outputs a pilot pressure to the turning control valve, and a boom operation valve outputs a pilot pressure to the boom main control valve. A boom-side regulating valve outputs no pilot pressure to the boom auxiliary control valve when a turning operation and a boom raising operation are performed concurrently.

First claim

1 . A hydraulic drive system of a construction machine, comprising:
a turning motor and a boom cylinder, each of which serves as a hydraulic actuator; a first hydraulic pump and a second hydraulic pump, whose respective tilting angles are adjustable independently of each other, each pump discharging hydraulic oil at a flow rate corresponding to the tilting angle of the pump; a turning control valve for controlling supply of the hydraulic oil to the turning motor, the turning control valve being disposed on a first bleed line extending from the first hydraulic pump; a boom main control valve and a boom auxiliary control valve each for controlling supply of the hydraulic oil to the boom cylinder, the boom main control valve being disposed on a second bleed line extending from the second hydraulic pump, the boom auxiliary control valve being disposed on the first bleed line; a turning operation valve that outputs a pilot pressure to the turning control valve; a boom operation valve that outputs a pilot pressure to the boom main control valve; and a boom-side regulating valve that outputs a pilot pressure to the boom auxiliary control valve in accordance with a boom raising operation when no turning operation is performed, and outputs no pilot pressure to the boom auxiliary control valve when a turning operation and a boom raising operation are performed concurrently.

2 . The hydraulic drive system of a construction machine according to claim 1 , wherein
the boom-side regulating valve is a solenoid proportional valve that outputs, to the boom auxiliary control valve, a pilot pressure proportional to the pilot pressure outputted from the boom operation valve when no turning operation is performed.

3 . The hydraulic drive system of a construction machine according to claim 1 , wherein
the boom-side regulating valve is a solenoid on-off valve that blocks a pilot line intended for the boom auxiliary control valve when a turning operation and a boom raising operation are performed concurrently.

4 . The hydraulic drive system of a construction machine according to claim 1 , further comprising:
a first regulator that adjusts the tilting angle of the first hydraulic pump based on a discharge pressure of the first hydraulic pump and a power shift pressure; a second regulator that adjusts the tilting angle of the second hydraulic pump based on a discharge pressure of the second hydraulic pump and the power shift pressure; and a solenoid proportional valve that outputs the power shift pressure to the first regulator and the second regulator.

5 . The hydraulic drive system of a construction machine according to claim 1 , further comprising:
a first regulator that adjusts the tilting angle of the first hydraulic pump based on a discharge pressure of the first hydraulic pump and a first power shift pressure; a first solenoid proportional valve that outputs the first power shift pressure to the first regulator; a second regulator that adjusts the tilting angle of the second hydraulic pump based on a discharge pressure of the second hydraulic pump and a second power shift pressure; and a second solenoid proportional valve that outputs the second power shift pressure to the second regulator.

6 . The hydraulic drive system of a construction machine according to claim 5 , further comprising a controller that, when a turning operation and a boom raising operation are performed concurrently, controls the first solenoid proportional valve in a manner to increase the first power shift pressure such that a discharge flow rate of the first hydraulic pump decreases, and controls the second solenoid proportional valve in a manner to decrease the second power shift pressure such that a discharge flow rate of the second hydraulic pump increases.

7 . The hydraulic drive system of a construction machine according to claim 2 , further comprising:
a first regulator that adjusts the tilting angle of the first hydraulic pump based on a discharge pressure of the first hydraulic pump and a power shift pressure; a second regulator that adjusts the tilting angle of the second hydraulic pump based on a discharge pressure of the second hydraulic pump and the power shift pressure; and a solenoid proportional valve that outputs the power shift pressure to the first regulator and the second regulator.

8 . The hydraulic drive system of a construction machine according to claim 3 , further comprising:
a first regulator that adjusts the tilting angle of the first hydraulic pump based on a discharge pressure of the first hydraulic pump and a power shift pressure; a second regulator that adjusts the tilting angle of the second hydraulic pump based on a discharge pressure of the second hydraulic pump and the power shift pressure; and a solenoid proportional valve that outputs the power shift pressure to the first regulator and the second regulator.

9 . The hydraulic drive system of a construction machine according to claim 2 , further comprising:
a first regulator that adjusts the tilting angle of the first hydraulic pump based on a discharge pressure of the first hydraulic pump and a first power shift pressure; a first solenoid proportional valve that outputs the first power shift pressure to the first regulator; a second regulator that adjusts the tilting angle of the second hydraulic pump based on a discharge pressure of the second hydraulic pump and a second power shift pressure; and a second solenoid proportional valve that outputs the second power shift pressure to the second regulator.

10 . The hydraulic drive system of a construction machine according to claim 3 , further comprising:
a first regulator that adjusts the tilting angle of the first hydraulic pump based on a discharge pressure of the first hydraulic pump and a first power shift pressure; a first solenoid proportional valve that outputs the first power shift pressure to the first regulator; a second regulator that adjusts the tilting angle of the second hydraulic pump based on a discharge pressure of the second hydraulic pump and a second power shift pressure; and a second solenoid proportional valve that outputs the second power shift pressure to the second regulator.

Assignees

• Kawasaki Heavy Ind Ltd

Inventors

• Kondo Akihiro
• Ito Makoto
• Fujiyama Kazuto

Classifications

• F15B11/17 Primary

  using two or more pumps · CPC title

• E02F9/2282

  Systems using center bypass type changeover valves · CPC title

• E02F9/2292

  Systems with two or more pumps · CPC title

• F15B2211/20576

  with multiple pumps · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title