US 2022/0154428 A1Published application

Hydraulic system in work machine

AssigneeKubota Corporation

InventorYuji FUKUDA

Life of this patent

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Abstract

A hydraulic system in a work machine includes a travel operation device provided in a pilot oil path between a hydraulic pump a travel pump and including an operation member and configured to generate a pilot pressure supplied via the pilot oil path and an additional pilot pressure in accordance with an operation amount of the operation member. The travel pump is to control a flow direction of hydraulic oil supplied to a travel motor based on the pilot pressure and the additional pilot pressure. A pressure selection valve is provided in a first coupling oil path to select a selected pressure from the pilot pressure and the additional pilot pressure to apply the selected pressure to the pilot hydraulic oil in the second coupling oil path. A pressure adjustment valve is provided in a second coupling oil path to control the selected pressure to be an adjusted pilot pressure.

Claims34

Dependent claims

A hydraulic system in a work machine, comprising:

a travel motor to be driven by hydraulic oil to rotate a drive shaft of a travel machine of the work machine;
a travel pump to supply the hydraulic oil to the travel motor to drive the travel motor;
a hydraulic pump to supply pilot hydraulic oil;
a pilot oil path connecting the hydraulic pump and the travel pump to supply the pilot hydraulic oil to the travel pump;
a travel operation device provided in the pilot oil path between the hydraulic pump and the travel pump and including an operation member, the travel operation device being configured to generate a pilot pressure and an additional pilot pressure in accordance with an operation amount of the operation member, the pilot pressure being supplied via the pilot oil path;
an additional pilot oil path connecting the travel operation device and the travel pump to supply the additional pilot pressure to the travel pump, the travel pump being configured to control a flow direction of the hydraulic oil supplied to the travel motor based on the pilot pressure and the additional pilot pressure;
a drain oil path divided from the pilot oil path, the drain oil path comprising:
a first coupling oil path connecting the pilot oil path and the additional pilot oil path;
and
a second coupling oil path divided from the first coupling oil path;
a pressure selection valve provided in the first coupling oil path to select a selected pressure of the pilot hydraulic oil from the pilot pressure and the additional pilot pressure to apply the selected pressure to the pilot hydraulic oil in the second coupling oil path;
and
a pressure adjustment valve provided in the second coupling oil path to control the selected pressure to be an adjusted pilot pressure.

10 more elements

A hydraulic system in a work machine, comprising:

a travel motor to be driven by hydraulic oil to rotate a drive shaft of a travel machine of the work machine;
a travel pump to supply the hydraulic oil to the travel motor to drive the travel motor;
a hydraulic pump to supply pilot hydraulic oil;
a pilot oil path connecting the hydraulic pump and the travel pump to supply the pilot hydraulic oil to the travel pump;
a travel operation device provided in the pilot oil path between the hydraulic pump and the travel pump and including an operation member, the travel operation device being configured to generate a pilot pressure and an additional pilot pressure in accordance with an operation amount of the operation member, the pilot pressure being supplied via the pilot oil path;
an additional pilot oil path connecting the travel operation device and the travel pump to supply the additional pilot pressure to the travel pump, the travel pump being configured to control a flow direction of the hydraulic oil supplied to the travel motor based on the pilot pressure and the additional pilot pressure;
a drain oil path divided from the pilot oil path, the drain oil path comprising:
a first coupling oil path connecting the pilot oil path and the additional pilot oil path;
and
a second coupling oil path divided from the first coupling oil path;
a first check valve provided in the first coupling oil path to be opened such that the pilot hydraulic oil flows from the pilot oil path to the second coupling oil path and to be closed such that the pilot hydraulic oil does not flow from the second coupling oil path to the pilot oil path;
a second check valve provided in the first coupling oil path to be opened such that the hydraulic oil flows from the additional pilot oil path to the second coupling oil path and to be closed such that the pilot hydraulic oil does not flow from the second coupling oil path to the additional pilot oil path;
and
a pressure adjustment valve provided in the second coupling oil path to control the pilot pressure to be an adjusted pilot pressure and to control the additional pilot pressure to be an adjusted additional pilot pressure.

11 more elements

A hydraulic system in a work machine, comprising:

a travel motor to be driven by hydraulic oil to rotate a drive shaft of a travel machine of the work machine;
a travel pump to supply the hydraulic oil to the travel motor to drive the travel motor;
a hydraulic pump to supply pilot hydraulic oil;
a pilot oil path connecting the hydraulic pump and the travel pump to supply the pilot hydraulic oil to the travel pump;
a travel operation device provided in the pilot oil path between the hydraulic pump and the travel pump and including an operation member, the travel operation device being configured to generate a pilot pressure and an additional pilot pressure in accordance with an operation amount of the operation member, the pilot pressure being supplied via the pilot oil path;
an additional pilot oil path connecting the travel operation device and the travel pump to supply the additional pilot pressure to the travel pump, the travel pump being configured to control a flow direction of the hydraulic oil supplied to the travel motor based on the pilot pressure and the additional pilot pressure;
a pressure adjustment valve connected to the pilot oil path between the travel operation device and the travel pump to control the pilot pressure to be an adjusted pilot pressure;
and
an additional pressure adjustment valve connected to the additional pilot oil path between the travel operation device and the travel pump to control the additional pilot pressure to be an adjusted additional pilot pressure.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/667,539Filed 9 Feb 2022
Priority: JP 2017-1936033 Oct 2017
Published: 19 May 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification23 codes

E02F 9/2285
Hydraulic circuits: pilot-operated systems
E02F 9/2239
Control of flow rate; Load sensing arrangements: using two or more pumps with cross-assistance
E02F 9/2292
Hydraulic circuits: systems with two or more pumps
F15B 13/0422
Operated by fluid pressure: with manually-operated pilot valves, e.g. joysticks

Family

Application16/012,761Division · filed 20 Jun 2018
Application16/851,102Division · filed 17 Apr 2020
Application17/667,539Division
US 10,662,980 B2Related patent
US 11,280,064 B2Related patent
US 12,291,849 B2Related patent
US 2019/0101139 A1Published application
US 2020/0240439 A1Published application
US 2022/0154428 A1This patent

From the US filing history. Foreign family members aren’t listed.