Kabushiki Kaisha Komatsu Seisakusho

Other

Komatsu Corporation

Kiyoshi Shirai

Naoki Ishizaki

Teruo Akiyama

Takahide Takiguchi

Shigeru Shinohara

Koji Yamashita

Kazuo Uehara

Shinichi Shinozaki

Terruo Akiyama

Koichi Morita

Yosuke Oda

Shin-ichi Shinozaki

Toshio Maki

Isao Oki

Displacement control system for variable displacement hydraulic pump

In a hydraulic circuit system, when pressurized oil discharged from a single hydraulic pump is supplied to a plurality of actuators: the pressurized oil is supplied to heavily-loaded ones of the actuators at gradually reducing flow rates to reduce a shock, while supplied to lightly-loaded ones of the actuators at gradually increasing flow rates to increase working speeds of these lightly-loaded actuators. The hydraulic circuit system comprises a plurality of directional control valves (2) one of which is provided with pressure-compensated flow control valves (18) each of which is provided with a load lead-in passage having a restriction means (R). In addition, further comprised in the system are: relief valves (22, 22) for relieving the pressurized oil under the influence of load pressure of the actuators (3) operated by the directional control valves (2); a restriction orifice (24) provided in a drain side of each of the relief valves so as to produce pressure therein.

Hydraulic circuit system

This invention aims at providing a hydraulic circuit apparatus for supplying pressurized fluid into cylinders for a work implement arranged such that during normal operation of the work implement the flow rate of fluid discharged by a pump is controlled such that the difference between the discharge pressure of the pump and the load pressure is always kept constant, whilst during inching operation of the work implement the flow rate of fluid discharged by the pump is reduced. This circuit apparatus comprises a large diameter piston (9) for actuating a displacement regulating member (8) of a variable displacement pump (2) in a direction as to reduce the displacement of the pump; a small diameter piston (10) having pressure receiving chamber (10a) connected with discharge passage (2a) of the pump and adapted to actuate discharge regulating member (8) in a direction as to increase the displacement of the pump (2); a load sensing valve (11) for connecting or disconnecting pressure receiving chamber (9a) of the large piston (9) with or from the discharge passage; and apparatus (12, 13, 14) for applying a force to the load sensing valve to push its spool in a direction as to communicate the discharge passage (2a) of the pump with pressure receiving chamber (9a) of the large piston.

Hydraulic circuit apparatus for supplying fluid under pressure into

Operation valve with pressure compensation valve

Hydraulic apparatus with pressure compensating valves

Hydraulic circuit apparatus for operating work-implement actuating

This invention provides a hydraulic circuit apparatus arranged such that when each of operating valves is operated suddenly, the stability of each of actuators is improved, and when the operating valves are kept at their neutral positions, the flow rate of fluid discharged by a variable displacement pump is increased to improve the response of the hydraulic circuit, and when the actuators are supplied with pressurized fluid, pressure compensation is made by pressure compensating valves. This hydraulic circuit apparatus comprises a bleed-off circuit (11) connecting the discharge passage (1a) of the variable displacement pump (1) with a fluid tank; a bleed-off valve (12) provided in bleed-off circuit (11) and adapted to be kept at its communicating position (I) when the operating valves (2) assume their neutral positions, and also kept at its shut-off position when the operating valves assume either their first fluid supply positions or their second fluid supply positions; and a flow restrictor (13) provided in the bleed-off circuit.

Hydraulic circuit with pilot pressure controlled bypass

Hydraulic circuit utilizing a compensator pressure selecting value

A pressure compensating type hydraulic valve wherein a pressure compensation can be made according to the movement of the movable portion of a hydraulic actuator, and the movable portion of the actuator can be stopped against load pressure when it is located at its neutral position. This pressure compensating type hydraulic valve is arranged such that a spool (24) is moved in a valve hole (16) so as to allow a first actuating port (21) and a second actuating port (22) connected with pressure receiving chambers (13.sub.1, 13.sub.2), respectively, defined on both sides of a movable portion (13.sub.3) of a hydraulic actuator (13) to be selectively connected with or disconnected from a first pumping port and a second pumping port in which fluid under pressure discharged by a hydraulic pump (10) flows, through the intermediary of a first check valve (31) and a second check valve (32), respectively, both of which are preset at predetermined pressures, and either one of the actuating ports which is isolated from the pumping port is connected with either one of the tank ports (33.sub.1, 33.sub.2).

Pressure compensating type hydraulic valve

All but the circle drive motor of the implement actuators of a motor grader are divided into two groups each consisting of those which need not be operated simultaneously. The power system has three fixed displacement pumps for driving the circle drive motor via a circle control valve and the two implement actuator groups via respective implement control valve arrangements of carry-over parallel configurations. One of the pumps is connected to the two implement control valve arrangements via a restriction and a flow divider. A first demand valve controls communication between the other two pumps and the implement control valve arrangements in response to the pressure differential across the restriction, maintaining constant fluid flow to the valve arrangements regardless of engine speed or the loads on the implement actuators. A second demand valve likewise responds to a pressure differential across another restriction formed in a conduit communicating the first demand valve and the carry-over ports of the implement control valve arrangements with the circle control valve, maintaining constant fluid flow thereto.

Hydraulic power system for implement actuators in an off-highway

A directional change-over valve which has a valve body having connecting surfaces at both sides thereof, a spool slidably inserted into the valve body, a check valve replaceable depending upon utilities thereof, wherein the valve body has a plurality of valve chambers, the central valve chamber is communicated with the hole for mounting the check valve for removably mounting the check valve, passages are provided opening at the connecting surfaces of the valve body in the respective valve chambers, another passages are provided for connecting the interior of the check valve to the both side valve chambers to form parallel, tandem and series circuits. Thus, this invention simplifies the structure and circuits to provide a compact directional change-over valve device as a whole.

Directional change-over valve

Growing community of inventors

Kawasaki, Japan

Kiyoshi Shirai