# US 8,464,826 B2 · Hydraulic traveling vehicle

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- Number: US 8,464,826 B2
- Document ID: US8464826B2
- Status: Granted
- Kind: B2
- Application number: 12/282,637
- Filed: 2007-05-07
- Published: 2009-03-05
- Granted: 2013-06-18
- Earliest claimed: 2006-05-15
- Assignees: Komatsu Ltd.
- Applicants: Takeo Yamada; Jun Koizumi
- Inventors: Takeo Yamada; Jun Koizumi
- Web page: https://patentgrep.com/patent/US8464826B2

## CPC

- B62D 11/06: by means of a single main power source
- B62D 11/005: {Hydraulic control systems}
- E02F 9/2203: {Arrangements for controlling the attitude of actuators, e.g. speed, floating function}
- E02F 9/2228: {including an electronic controller}
- E02F 9/2242: {including an electronic controller}
- E02F 9/225: {Control of steering, e.g. for hydraulic motors driving the vehicle tracks (steering in general B62D)}
- E02F 9/2296: {Systems with a variable displacement pump}
- F15B 11/163: {for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation}
- F15B 11/17: using two or more pumps
- F16H 61/4139: Replenishing or scavenging pumps, e.g. auxiliary charge pumps
- F16H 61/448: Control circuits for tandem pumps or motors
- F16H 61/456: Control of the balance of torque or speed between pumps or motors
- F15B 2211/20546: variable capacity
- F15B 2211/20576: with multiple pumps
- F15B 2211/30535: the pressure compensating valve is arranged between pressure source and directional control valve
- F15B 2211/329: actuated by fluid pressure
- F15B 2211/7053: Double-acting output members
- F15B 2211/7058: Rotary output members
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00)
- F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F16H: GEARING

## Abstract

A hydraulic traveling vehicle includes a right-travel motor a left-travel motor, a hydraulic pump, a merging/diverging valve and a travel switching unit. The merging/diverging valve is configured to switch between merging and separating a first hydraulic circuit and a second hydraulic circuit. The travel switching unit is configured to switch between a state where sharp turning takes place as a result of one of the right-travel motor and the left-travel motor being stopped and the other being driven, with the merging/diverging valve being in a merging state, and a state where gentle turning takes place as a result of the right-travel motor and the left-travel motor being driven at different rotational speeds, with the merging/diverging valve being in a diverging state.

## Claims

### Claim 1

A hydraulic traveling vehicle comprising:
a right-travel motor arranged in a first hydraulic circuit to be driven by pressurized oil that flows in the first hydraulic circuit;
a left-travel motor arranged in a second hydraulic circuit to be driven by pressurized oil that flows in the second hydraulic circuit;
a first pilot circuit through which pilot pressurized oil flows to regulate the pressurized oil supplied to the right-travel motor, the first pilot circuit being hydraulically separate from the first and second hydraulic circuits;
a second pilot circuit through which pilot pressurized oil flows to regulate the pressurized oil supplied to the left-travel motor, the second pilot circuit being hydraulically separate from the first and second hydraulic circuits;
a hydraulic pump having a first hydraulic oil supply unit configured and arranged to supply the pressurized oil to the right-travel motor via the first hydraulic circuit and a second hydraulic oil supply unit configured and arranged to supply the pressurized oil to the left-travel motor via the second hydraulic circuit;
a merging/diverging valve configured and arranged to switch between a merging state to merge the first hydraulic circuit and the second hydraulic circuit and a diverging state to separate the first hydraulic circuit and the second hydraulic circuit; and
a travel switching unit configured to switch the merging/diverging valve between the merging state and the diverging state depending on whether the hydraulic traveling vehicle is in a sharp turning state or a gentle turning state so that the merging/diverging valve is placed in the merging state when the hydraulic traveling vehicle is in the sharp turning state, with the sharp turning state being as a result of one of the right-travel motor and the left-travel motor being stopped and the other being driven, and the gentle turning state being a result of the right-travel motor and the left-travel motor being driven at different rotational speeds.

### Claim 2 (depends on 1)

The hydraulic traveling vehicle according to claim 1, further comprising:
a right-travel valve arranged in the first hydraulic circuit to regulate the pressurized oil supplied to the right-travel motor;
a left-travel valve arranged in the second hydraulic circuit to regulate the pressurized oil supplied to the left-travel motor;
a travel operation unit configured and arranged to regulate pilot pressure supplied by the pilot pressurized oil in the first pilot circuit and the second pilot circuit to the right-travel valve and the left-travel valve, respectively, according to an amount of a travel operation;
a right-pressure detector configured and arranged to detect the pilot pressure supplied by the pilot pressurized oil in the first pilot circuit to the right-travel valve; and
a left-pressure detector configured and arranged to detect the pilot pressure supplied by the pilot pressurized oil in the second pilot circuit to the left-travel valve,
the travel switching unit being further configured to identify whether the hydraulic traveling vehicle is in the sharp turning state or the gentle turning state based on detection results of the right-pressure detector and the left-pressure detector.

### Claim 3 (depends on 1)

The hydraulic traveling vehicle according to claim 1, further comprising
a working equipment arranged in one of the first hydraulic circuit or the second hydraulic circuit to be driven by pressurized oil,
the travel switching unit being further configured to switch between
a state where the gentle turning is carried out and the working equipment is not driven with the merging/diverging valve being in the diverging state, and
a state where the gentle turning is carried out and the working equipment is driven with the merging/diverging valve being in the merging state.