Hydraulic drive system for work machine

Patent metadata

Field	Value
Publication number	US-11208787-B2
Application number	US-201816958516-A
Country	US
Kind code	B2
Filing date	Dec 25, 2018
Priority date	Dec 28, 2017
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

A hydraulic drive system includes a swing directional control valve 81 and a third boom directional control valve 82 that are connected to a third hydraulic pump 33. Furthermore, the hydraulic drive system includes: a second auxiliary directional control valve 84 that is connected to the third hydraulic pump 33, and is connectable with a second special hydraulic actuator 64 for driving special attachments; and a first selector valve 96 that is connected to the third hydraulic pump 33 upstream of the second auxiliary directional control valve 84, and is connectable with an additional hydraulic pump 97. The first selector valve 96 switches the hydraulic fluid source of the second special hydraulic actuator 64 connected to the second auxiliary directional control valve 84 at least between the third hydraulic pump 33 and the additional hydraulic pump 97. Operability for combined operation of a special attachment can be improved in the hydraulic drive system equipped in advance with an auxiliary directional control valve that is connectable with an additional hydraulic actuator for driving the special attachment.

First claim

The invention claimed is:

1. A hydraulic drive system for a work machine, the hydraulic drive system comprising:
a first hydraulic pump and a second hydraulic pump that supply a hydraulic fluid at least to a first hydraulic actuator and a second hydraulic actuator;
a third hydraulic pump that supplies the hydraulic fluid at least to a third hydraulic actuator and the first hydraulic actuator;
a first-hydraulic-actuator first directional control valve that controls a flow of the hydraulic fluid supplied from the first hydraulic pump to the first hydraulic actuator;
a second-hydraulic-actuator second directional control valve that controls a flow of the hydraulic fluid supplied from the first hydraulic pump to the second hydraulic actuator;
a first-hydraulic-actuator second directional control valve that controls a flow of the hydraulic fluid supplied from the second hydraulic pump to the first hydraulic actuator;
a second-hydraulic-actuator first directional control valve that controls a flow of the hydraulic fluid supplied from the second hydraulic pump to the second hydraulic actuator;
a first auxiliary directional control valve that is connectable with a first special hydraulic actuator for driving an additionally attachable special attachment, and is configured to control a flow of the hydraulic fluid supplied from the second hydraulic pump to the first special hydraulic actuator;
a third-hydraulic-actuator directional control valve that controls a flow of the hydraulic fluid supplied from the third hydraulic pump to the third hydraulic actuator; and
a first-hydraulic-actuator third directional control valve that controls a flow of the hydraulic fluid supplied from the third hydraulic pump to the first hydraulic actuator,
the first-hydraulic-actuator first directional control valve and the second-hydraulic-actuator second directional control valve being connected, in parallel with each other, to the first hydraulic pump,
the first-hydraulic-actuator second directional control valve, the second-hydraulic-actuator first directional control valve and the first auxiliary directional control valve being connected, in parallel with each other, to the second hydraulic pump,
the third-hydraulic-actuator directional control valve and the first-hydraulic-actuator third directional control valve being connected, in parallel with each other, to the third hydraulic pump, wherein
the hydraulic drive system includes:
a second auxiliary directional control valve that is connected to the third hydraulic pump, is connectable with a second special hydraulic actuator for driving the special attachment or an additionally attachable special attachment different from the special attachment, and is configured to control a flow of the hydraulic fluid to the second special hydraulic actuator;
a selector valve that is connected to the third hydraulic pump upstream of the second auxiliary directional control valve, and is connectable with a retrofit additional hydraulic pump,

the selector valve being configured to switch a hydraulic fluid source of the second special hydraulic actuator connected to the second auxiliary directional control valve at least between the third hydraulic pump and the additional hydraulic pump, and wherein
the selector valve is a two-position selector valve that is switched between a first switch position for guiding the hydraulic fluid supplied from the third hydraulic pump to the second auxiliary directional control valve and a second switch position for guiding the hydraulic fluid supplied from the additional hydraulic pump to the second auxiliary directional control valve.

2. The hydraulic drive system for a work machine, according to claim 1 , wherein
the second auxiliary directional control valve is connected, in parallel with the third-hydraulic-actuator directional control valve and the first-hydraulic-actuator third directional control valve, to the third hydraulic pump via a parallel hydraulic line,
a downstream end portion of the parallel hydraulic line is connected to a hydraulic line between the selector valve and the second auxiliary directional control valve, and
a variable restrictor is disposed on the parallel hydraulic line.

3. The hydraulic drive system for a work machine, according to claim 1 , wherein
the work machine is a hydraulic excavator including at least a swingable swing structure, a boom attached to the swing structure in a raiseable and lowerable manner, and an arm pivotably attached to a tip of the boom,
the first hydraulic actuator is a boom cylinder that drives the boom,
the second hydraulic actuator is an arm cylinder that drives the arm, and
the third hydraulic actuator is a swing hydraulic motor that swing-drives the swing structure.

4. A hydraulic drive system for a work machine, the hydraulic drive system comprising:
a first hydraulic pump and a second hydraulic pump that supply a hydraulic fluid at least to a first hydraulic actuator and a second hydraulic actuator;
a third hydraulic pump that supplies the hydraulic fluid at least to a third hydraulic actuator and the first hydraulic actuator;
a first-hydraulic-actuator first directional control valve that controls a flow of the hydraulic fluid supplied from the first hydraulic pump to the first hydraulic actuator;
a second-hydraulic-actuator second directional control valve that controls a flow of the hydraulic fluid supplied from the first hydraulic pump to the second hydraulic actuator;
a first-hydraulic-actuator second directional control valve that controls a flow of the hydraulic fluid supplied from the second hydraulic pump to the first hydraulic actuator;
a second-hydraulic-actuator first directional control valve that controls a flow of the hydraulic fluid supplied from the second hydraulic pump to the second hydraulic actuator;
a first auxiliary directional control valve that is connectable with a first special hydraulic actuator for driving an additionally attachable special attachment and is configured to control a flow of the hydraulic fluid supplied from the second hydraulic pump to the first special hydraulic actuator;
a third-hydraulic-actuator directional control valve that controls a flow of the hydraulic fluid supplied from the third hydraulic pump to the third hydraulic actuator; and
a first-hydraulic-actuator third directional control valve that controls a flow of the hydraulic fluid supplied from the third hydraulic pump to the first hydraulic actuator,
the first-hydraulic-actuator first directional control valve and the second-hydraulic-actuator second directional control valve being connected, in parallel with each other, to the first hydraulic pump,
the first-hydraulic-actuator second directional control valve, the second-hydraulic-actuator first directional control valve and the first auxiliary directional control valve being connected, in parallel with each other, to the second hydraulic pump,
the third-hydraulic-actuator directional control valve and the first-hydraulic-actuator third directional control valve being connected, in parallel with each other, to the third hydraulic pump, wherein
the hydraulic drive system includes:
a second auxiliary directional control valve that is connected to the third hydraulic pump, is connectable with a second special hydraulic actuator for driving the special attachment or an additionally attachable special attachment different from the special attachment, and is configured to control a flow of the hydraulic fluid to the second special hydraulic actuator;
a selector valve that is connected to the third hydraulic pump upstream of the second auxiliary directional control valve, and is connectable with a retrofit additional hydraulic pump,

the selector valve being configured to switch a hydraulic fluid source of the second special hydrauli

Assignees

• Hitachi Construction Mach Co

Inventors

• Hagiwara Masayuki
• Kodaka Katsuaki
• Kanehama Mitsuhiko

Classifications

• F15B2211/30565

  having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve · CPC title

• F15B2211/7142

  the output members being arranged in multiple groups · CPC title

• F15B11/17 Primary

  using two or more pumps · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• E02F9/2242 Primary

  including an electronic controller · CPC title