Motors: expansible chamber type – Fluid supply through diverse paths to single expansible chamber
Patent
1996-01-19
1997-12-02
Lopez, F. Daniel
Motors: expansible chamber type
Fluid supply through diverse paths to single expansible chamber
91 28, 91524, 91529, 13759618, F01B 2502
Patent
active
056924275
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a flow reinforcement directional control valve for supplying a pressurized discharge fluid from a hydraulic pump to a plurality of actuators to enable each of them to operate at a high speed. The invention may be used in a pressurized fluid supply unit in which a pressurized discharge fluid from a hydraulic pump is supplied to such a plurality of actuators via a plurality of directional control valves, respectively.
BACKGROUND ART
As a pressurized fluid supply unit for supplying a pressurized discharge fluid from a hydraulic pump, there has hitherto been known an apparatus In which a plurality of directional control valves are provided in a discharge path of the hydraulic pump to supply the pressurized discharge fluid to a plurality of actuators, respectively. For example, a power shovel hydraulic circuit has been used in which a boom cylinder, an arm cylinder, a bucket cylinder, a turning motor, and a right hand side and a left hand side traveling motor are supplied with the pressurized fluid via a directional control valve for boom, a directional control valve for arm, a directional control valve for bucket, and a right hand side and a left hand side traveling purpose directional control valve that are provided in the discharge path of the hydraulic pump.
In order to satisfy a common specification, such directional control valves as used in such a hydraulic circuit should be of an identical size, and a maximum flow that can be supplied to each such individual actuator should be identical in order to make a maximum operating speed thereof identical. Accordingly, where a particular actuator is to be operated at a high speed, it has been a practice that a large volumetric flow is supplied to the particular actuator by providing a flow reinforcement directional control valve in association therewith.
For example, since in the above mentioned hydraulic circuit for a power shovel, a boom cylinder and an arm cylinder need to be operated at a high speed, it has been a practice that a flow reinforcement directional control valve for boom and a flow reinforcement directional control valve for arm are arranged in parallel to a directional control valve for boom and the directional control valve for arm to ensure that a large volumetric flow can be supplied to the boom cylinder and the arm cylinder.
If a particular actuator is to be supplied with a large volumetric flow as mentioned above, the same number of flow reinforcement directional control valves are required as the number of such particular actuators. Also, such flow reinforcement directional control valves must each have a spool slidably inserted in a valve block. Therefore, it will follow that the number of such valve blocks is increased with the result that an overall pressurized fluid supply unit must be large-sized, thus enlarging a space for it to be installed.
At this point, it should be noted that a valve has hitherto been known, as disclosed in Japanese Unexamined Utility Model Publication No. Hei 04-134969, in which a pair of spools are slidably inserted in a single valve block and the movements of these two spools may bring about the controlled opening and closing of a pair of circuits. Note, however, there that since such a valve has the two spools each energized by a spring in a single direction and has adopted a construction in which they are each thrusted in the opposite direction under a pilot pressure applied against the spring, the valve has only a function to cause the pressurized fluid either to flow or not to flow with a circuit opened or closed, respectively.
For this reason, if the above mentioned valve is used as a flow reinforcement directional control valve for boom or a flow reinforcement directional control valve for arm, it will only function either to enable or to disable the pressurized fluid to be supplied to the boom cylinder or the arm cylinder; it will have no function for a flow to be returned.
To make the matter worse, since a return fluid from an actuator Is passed thr
REFERENCES:
patent: 4492251 (1985-01-01), Blake
patent: 4729408 (1988-03-01), Coutant
patent: 4763691 (1988-08-01), Hahmann
patent: 4924902 (1990-05-01), Lewis et al.
Honda Nobuhisa
Karakama Tadao
Yoshida Nobumi
Kananen Ronald P.
Komatsu Ltd.
Lopez F. Daniel
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