Hydraulic drive device for working machine

Patent metadata

Field	Value
Publication number	US-9341198-B2
Application number	US-201214118141-A
Country	US
Kind code	B2
Filing date	May 17, 2012
Priority date	May 19, 2011
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

A hydraulic drive device for a hydraulic excavator, includes: a first hydraulic pump; a first boom directional control valve and a second arm directional control valve which are connected in parallel to the first pump; a second hydraulic pump; and a second boom directional control valve and a first arm directional control valve which are connected in parallel to the second pump; wherein: the hydraulic drive device also includes: a third hydraulic pump; a third boom directional control valve connected to the third pump and controlling the flow of pressure oil supplied to a boom cylinder; and a third arm directional control valve connected in tandem with the third boom directional control valve and controlling the flow of pressure oil supplied to an arm cylinder.

First claim

The invention claimed is:

1. A hydraulic drive device for a working machine, the hydraulic drive device being provided in the working machine including a body and a working device attached to the body, the working device including a boom connected to the body so as to be rotatable in an up/down direction, an arm connected to a distal end of the boom so as to be rotatable in the up/down direction, a boom cylinder driving the boom, and an arm cylinder driving the arm, the hydraulic drive device comprising:
a first hydraulic pump and a second hydraulic pump which supply pressure oil for operating the boom cylinder and the arm cylinder respectively; a first boom directional control valve and a second arm directional control valve connected in parallel to the first hydraulic pump so that the first boom directional control valve controls a flow of the pressure oil supplied to the boom cylinder and the second arm directional control valve controls a flow of the pressure oil supplied to the arm cylinder; and a second boom directional control valve and a first arm directional control valve connected in parallel to the second hydraulic pump so that the second boom directional control valve controls a flow of the pressure oil supplied to the boom cylinder and the first arm directional control valve controls a flow of the pressure oil supplied to the arm cylinder; wherein the hydraulic drive device further comprises:
a third hydraulic pump which supplies pressure oil for operating the boom cylinder and the arm cylinder; a third boom directional control valve connected to the third hydraulic pump so as to control a flow of the pressure oil supplied to the boom cylinder; and a third arm directional control valve connected in tandem with the third boom directional control valve on the downstream side of the third boom directional control valve so as to control a flow of the pressure oil supplied to the arm cylinder.

2. A hydraulic drive device for a working machine according to claim 1 , wherein:
the body includes an upper structure; and
the hydraulic drive device further comprises a swing motor which drives the upper structure, and a swing directional control valve which is connected to the third hydraulic pump so as to control a flow of the pressure oil supplied to the swing motor.

3. A hydraulic drive device for a working machine according to claim 2 , wherein:
the swing directional control valve and the third boom directional control valve are connected in parallel.

4. A hydraulic drive device for a working machine according to claim 2 , wherein:
the working device includes a bucket connected to a distal end of the arm so as to be rotatable in the up/down direction, and a bucket cylinder operating the bucket;
the hydraulic drive device further comprises a bucket directional control valve which controls a flow of the pressure oil supplied to the bucket cylinder; and
the first boom directional control valve, the second arm directional control valve and the bucket directional control valve are connected in parallel.

5. A hydraulic drive device for a working machine according to claim 4 , further comprising:
a second auxiliary directional control valve which is connected to the third hydraulic pump.

6. A hydraulic drive device for a working machine according to claim 5 , wherein:
the swing directional control valve, the third boom directional control valve and the second auxiliary directional control valve are connected in parallel.

7. A hydraulic drive device for a working machine according to claim 6 , wherein:
the second auxiliary directional control valve has an additional pump port to which an additional hydraulic pump can be connected.

8. A hydraulic drive device for a working machine according to claim 4 , further comprising:
a first variable throttle which is provided on an upstream side of the second arm directional control valve.

9. A hydraulic drive device for a working machine according to claim 2 , wherein:
the hydraulic drive device further comprises an engine;
the working device further includes a bucket connected to a distal end of the arm so as to be rotatable in the up/down direction, and a bucket cylinder operating the bucket;
the hydraulic drive device further comprises a bucket directional control valve which controls a flow of the pressure oil supplied to the bucket cylinder;
the first hydraulic pump, the second hydraulic pump and the third hydraulic pump consist of variable displacement hydraulic pumps which are driven by the engine, respectively;
the hydraulic drive device further comprises a first torque control unit which can variably control pump torque of the first hydraulic pump, a second torque control unit which can variably control pump torque of the second hydraulic pump, and a third torque control unit which can variably control pump torque of the third hydraulic pump; and
the first torque control unit makes control to increase the pump torque of the first hydraulic pump during combined operation of the upper structure and the bucket.

10. A hydraulic drive device for a working machine according to claim 2 , wherein:
the hydraulic drive device further comprises an engine;
the working device further includes a bucket connected to a distal end of the arm so as to be rotatable in the up/down direction, and a bucket cylinder operating the bucket;
the hydraulic drive device further comprises a bucket directional control valve which controls a flow of the pressure oil supplied to the bucket cylinder;
the first hydraulic pump, the second hydraulic pump and the third hydraulic pump consist of variable displacement hydraulic pumps which are driven by the engine, respectively;
the hydraulic drive device further comprises a first torque control unit which can variably control pump torque of the first hydraulic pump and pump torque of the second hydraulic pump concurrently, and a second torque control unit which can variably control pump torque of the third hydraulic pump; and
the first torque control unit makes control to increase the pump torque of the first hydraulic pump and the pump torque of the second hydraulic pump during combined operation of the upper structure and the bucket.

11. A hydraulic drive device for a working machine according to claim 1 , wherein:
the third boom directional control valve has a boom raising selection position which is a selection position for rotating the boom upward and a boom lowering selection position which is a selection position for rotating the boom downward, and a block port which blocks the supply of the pressure oil discharged from the third hydraulic pump to the boom cylinder is provided in the boom lowering selection position.

12. A hydraulic drive device for a working machine according to claim 11 , further comprising:
a regenerative circuit which is provided in the boom lowering selection position of the third boom directional control valve so that the oil discharged from a bottom chamber of the boom cylinder can be regeneratively supplied to a rod chamber of the boom cylinder during the boom lowering operation; and
a boom directional control valve control unit which holds the third boom directional control valve in the boom lowering selection position and holds the first boom directional control valve and the second boom directional control valve in neutral positions when bottom pressure of the boom cylinder is not lower than a predetermined pressure during the boom lowering operation, and which holds the third boom directional control valve in the boom lowering selection position, holds the first boom directional control valve in the boom lowering selection position where the pressure oi

Assignees

• Nakamura Tsuyoshi
• Nakamura Kazunori
• Okano Yasuo
• Ishikawa Kouji
• Sato Kensuke
• Azuma Hiroyuki
• Kanehama Mitsuhiko
• Kajita Yusuke
• Hitachi Construction Machinery

Inventors

• Nakamura Tsuyoshi
• Nakamura Kazunori
• Okano Yasuo
• Ishikawa Kouji
• Sato Kensuke
• Azuma Hiroyuki
• Kanehama Mitsuhiko
• Kajita Yusuke

Classifications

• E02F9/123 Primary

  Drives or control devices specially adapted therefor (E02F9/125 and E02F9/128 take precedence) · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• F15B15/20 Primary

  Other details {, e.g. assembly with regulating devices} · CPC title

• E02F9/2292

  Systems with two or more pumps · CPC title

• E02F9/2285

  Pilot-operated systems · CPC title