Komatsu Corporation

Kabushiki Kaisha Komatsu Seisakusho

Sadao Nunotani

Naoki Ishizaki

Seita Hayashi

Hideki Kado

Tadao Karakama

Toshiro Takano

Kazuo Uehara

Mitsuru Arai

Masayuki Tanaami

Mitsuru Oshiro

Koichi Morita

Tosiyuki Akasaka

Toshiyuki Akasaka

Hiroshi Endo

Shuuji Hori

Jun Maruyama

Masatake Tamaru

Kenzo Kimoto

Masami Naruse

Hisashi Asada

Nobuhisa Honda

Tatsuya Futami

Kenji Kanemaru

Takahiro Miyata

Ken Furukawa

Tatsumi Tada

Shuki Akushicki

The present invention lowers energy loss while at the same time enhancing the responsiveness of a steering control system. When a steering controller is operated rapidly, the aperture area of a steering flow control valverapidly increases, and the differential pressure (Pp'-PL) across the steering flow control valverapidly decreases. When the differential pressure (Pp&#x2032;-PL) across the steering flow control valverapidly decreases, a flow control valveis biased by the spring force of a springand quickly moves to the side of a valve positionto increase the differential pressure (Pp&#x2032;-PL) and make it correspond to a set pressure. Thus, the pressure oil of a surplus flow &#x3b1;, which up to this point has been flowing to a discharge oil line, is quickly supplied from the flow control valveto a steering hydraulic cylindervia the steering flow control valve. Thus, an output Q&#x2032; starts quickly relative to an input St.

Vehicular steering control device

A hydraulic pipe arrangement of a working machine is not in contact with an obstacle and no torsion and no bending are generated. Accordingly, in a hydraulically driven type working machine provided with a boom ( ) having a vertical swing supporting point supported at a base end side by a machine frame and a joint connection supporting point in a front end side, an arm ( ) connected in a base end side to the joint connection supporting point, a boom driving hydraulic cylinder ( a) hoisting around a hoist supporting point provided in the machine frame so as to drive the boom, an arm driving hydraulic cylinder ( ), and a working tool driving hydraulic cylinder ( ), a swivel joint mechanism relaying a hydraulic pipe arrangement from a side of the machine frame is provided at a center of at least one of the vertical swing supporting point, the joint connection supporting point and the boom driving hydraulic cylinder hoist supporting point.

Hydraulically driven type working machine

First and second pistons are provided in a body, the first piston is restricted by the body and the second piston, and the second piston is restricted by the body and a second piston restricting part. Thus, the first piston can be stopped at three positions, and the respective stop positions can be adjusted. Therefore, when rotation speeds of left and right rotating bodies are switched among three levels by a hydraulic motor, a difference of the number of rotations between the left and right rotating bodies can be eliminated, and a vehicle can be suppressed from deviating from a course while it is going straight. Further, a mounting area of the hydraulic pump can be decreased and a structure can be made simple. The rotation speed of the hydraulic motor is changed among the three levels by a simple structure and simple control without using a complex structure such as a servo valve and complex control. Further, the rotation speeds of the rotating bodies are switched among three or more levels by discontinuously positioning the piston not only at three positions but also three or more positions. Furthermore, the mounting area of the hydraulic pump is made small.

Positioning device, capacity controller using positioning device, and speed changing device

The invention can prevent a heat generation and a seizure due to a sliding friction between a piston and a cylinder in inclined shaft type and swash plate type hydraulic pumps even when they are made high speed. In order to achieve this, a piston pump motor comprises a cylinder block (,) rotatably supported within a case (,), having suction and discharge ports (,) in a side of one cylindrical end surface, being provided with a plurality of cylinder holes (,) connected to the suction and discharge ports and arranged on an inside circumference at a uniform interval, and a piston (,) rotated by a drive shaft (,), sliding within the cylinder hole in a sealing manner and having a part moving forward and backward from a side of the other end surface of the cylinder block, wherein an oil introduction groove (,) communicating with an inner portion of the case is provided in any one of a portion disposed on an outer periphery of the piston and moving forward and backward from the side of the other end surface of the cylinder block, and a portion disposed on an inner periphery of the cylinder hole and at which a part of the piston moves forward and backward from the side of the other end surface.

Piston pump motor

Travel drive apparatus for hydraulic drive work vehicles and control therefor

A travel drive apparatus for a hydraulic drive work vehicle and control method therefor, the apparatus including: a travel hydraulic pump driven by the power of an engine; a hydraulic motor that receives discharged oil from the travel hydraulic pump and causes the vehicle to travel; a travel changeover valve that receives the discharged oil from the travel hydraulic pump, supplies the discharged oil to the hydraulic motor and discharges return oil from the hydraulic motor to a tank, in which the travel drive apparatus comprises; an accelerator for controlling an engine rotational speed; an operation unit for selecting vehicle forward travel, stop, and reverse travel; the travel changeover valve being adapted for receiving signals from the operation unit, switching the discharge oil supplied from the travel hydraulic pump to the hydraulic motor, and controlling vehicle forward travel, stop and reverse travel; a relief valve that regulates pressure for controlling the hydraulic motor when the vehicle has decelerated, positioned between the travel changeover valve and the hydraulic motor; and a pressurizing unit for raising the set pressure at the relief valve controlling the hydraulic motor when the engine rotational speed is increased, while switching the vehicle from forward travel to reverse travel, or from reverse travel to forward travel, so that the work vehicle may switch over from forward to reverse travel; or vice versa, while exhibiting good acceleration performance.

Travel drive apparatus for hydraulic drive work vehicle and control method therefor

Backpressure control circuit for hydraulic drive device

Counter balance valve

Hydraulic circuit for hydraulically driven working vehicle

Driving device for a hydraulic motor

Capacity control device for a hydraulic motor for a hydraulically driven

Hydraulic braking apparatus having two safety valves

Swash plate angle changing apparatus for a piston pump/motor of swash

A pressure control system in which a pressure in a back pressure chamber of a flow control valve is controlled according to a throttle opening of a pilot valve to locate stationary the valve body of the flow control valve at a position corresponding to the throttle opening of the pilot valve. In the system, a fixed throttle is provided in an oil passage extended to the back pressure chamber of the flow control valve, thereby applying a dampering action to the valve body.

Hydraulic pressure control system

Growing community of inventors

Oyama, Japan

Sadao Nunotani