Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – Condition responsive means for modifying working member...
Patent
1996-08-14
1997-12-30
Nguyen, Hoang
Motors: expansible chamber type
Plural relatively movable or rigidly interconnected working...
Condition responsive means for modifying working member...
91530, F15B 1100
Patent
active
057017964
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a hydraulic apparatus for traveling for driving a crawler type working vehicle, such as a power shovel and so forth by supplying a pressurized fluid discharged from one hydraulic pump to left and right hydraulic motors for traveling.
BACKGROUND ART
As a power shovel, there has been known a crawler type one, in which a vehicle body is provided on a traveling body for turning by turning hydraulic motors, a boom, an arm and a bucket are provided on the vehicle body for pivotal movement in vertical direction by means of a boom cylinder, an arm cylinder and a bucket cylinder, and left and right crawlers provided on the traveling body are driven by respective of left and right hydraulic motors for traveling.
As a hydraulic circuit for supplying a pressurized fluid discharged from one hydraulic pump to respective hydraulic actuators of such power shovel, there has been known one hydraulic circuit disclosed in Japanese Unexamined Patent Publication (Kokai) No. Heisei 4-244604, for example. The disclosed circuit is constructed with one variable displacement hydraulic pump which displacement is controlled so that a pressure difference between a load pressure of a hydraulic actuator and a discharge pressure of the pump becomes constant, a plurality of direction switching valves connected to discharge side of the variable displacement hydraulic pump to be supplied pressurized fluid to respective hydraulic actuators, and a plurality of pressure compensation valves, each being constructed with a load check valve provided at the inlet side of each direction switching valve and a pressure reduction valve pushing the load check valve in a closing direction by a downstream pressure against each load pressure.
When the hydraulic circuit for traveling is constructed with the hydraulic circuit as set forth above, the hydraulic circuit becomes as shown in FIG. 1, for example. Namely, left and right direction switching valves 5 and 6 are provided in a discharge passage 2 of the variable displacement hydraulic pump 1 for supplying pressurized fluid to left and right hydraulic motors 3 and 4 for traveling. At inlet sides of the left and right direction switching valves 5 and 6, pressure compensation valves 9, each is constructed with each load check valve 7 and a pressure reduction valve 8 pushing the load check valve 7 in closing direction by a downstream pressure against each load pressure, are provided. Then, respective load pressure detecting ports 5a and 6a of the left and right direction switching valves 5 and 6 are respectively connected to the pressure reduction valve 8 of the respective pressure compensation valve 9. A downstream pressure of the pressure reduction valve 8 is supplied to a displacement control valve 11 via a load pressure introduction passage 10 for controlling the displacement of the variable displacement hydraulic pump 1 by a displacement control cylinder 12 so that a pressure difference between the load pressure and the discharge pressure of the pump becomes constant. Furthermore, with respective pressure compensation valves 9, a meter-in pressure difference of the left and right direction switching valves 5 and 6 is controlled to be constant. It should be noted that 13 denotes a counter-balance valve.
In such hydraulic circuit, left and right turning traveling is performed by differentiating revolution speeds of the left and right hydraulic motors 3 and 4 for traveling by differentiating meter-in open areas of the left and right direction switching valves 5 and 6 by means of an operation lever 15 or so forth. However, at this time, traveling speed is lowered.
Namely, since turning resistance becomes large during left and right turning traveling, the hydraulic motor for traveling located at the inner side of turning circle which revolution speed is lower, becomes braking state to make driving pressure zero (or set pressure of the counter-balance valve). On the other hand, the driving pressure of the hydraulic motor for traveling located at the
REFERENCES:
patent: 4149565 (1979-04-01), Jennings et al.
patent: 4166506 (1979-09-01), Tezuka et al.
patent: 4489644 (1984-12-01), Tsukimoto et al.
patent: 4534268 (1985-08-01), Yagyu et al.
patent: 4557291 (1985-12-01), Hashimoto
Akashi Mitsumasa
Takano Toshiro
Komatsu Ltd.
Nguyen Hoang
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