Komatsu Corporation

Daisuke Kozuka

Shuuji Hori

Toshihiko Nishiyama

Takahisa Iino

Mitsumasa Akashi

Tadashi Iijima

Masatoshi Ikeda

Masayoshi Mototani

Hisashi Asada

Akira Hasebe

Kazunori Ikei

Norihide Mizoguchi

Yasukuni Kawashima

Yasuhiro Sato

Masayuki Tajima

Hideyuki Seiyama

Wataru Sumino

Taisei Okubo

Koichi Miyake

Takehide Kitagawa

A control method of an excavator including: a first circuit of an open circuit including a main valve controlling inflow of hydraulic oil from a main pump to a working equipment cylinder, and a tank to which the oil flowed out of the cylinder is ejected via the main valve; a second circuit of a closed circuit including a first valve between swing pump and motor; and a second valve on a first passage between the main valve and the tank, adjusting back pressure of the main valve, the control method includes: causing the oil to flow into a second passage around a spool of the first valve from an upstream portion of the first passage between the main valve and the second valve; and causing the oil to flow out of the second passage to a downstream portion of the first passage between the second valve and the tank.

Hydraulic system, excavator, and control method of excavator

A hydraulic servo drive device includes: a pilot spool for switching supply and shutoff of oil; a servo piston slid in accordance with the pilot spool; a stroke sensor for detecting a displacement of the servo piston; a first hydraulic chamber in which oil for moving the servo piston is flowed; a first piston oil path for communicating a pump port to which oil is supplied from a pump with a first hydraulic chamber; and a discharge circulating oil path for communicating the first hydraulic chamber with a drain port.

Hydraulic servo-drive device and variable turbo-supercharger using the same

An engine includes a variable geometry turbocharger, an EGR valve device, a hydraulic servo drive device that drives the variable geometry turbocharger, a hydraulic servo drive device that drives the EGR valve device, an electronic proportional control valve (EPC valve) that supplies pilot pressure oil to the hydraulic servo drive device, and an electronic proportional control valve (EPC valve) that supplies pilot pressure oil to the hydraulic servo drive device, the EPC valves being attached to the EGR valve device.

Engine with turbocharger and EGR

A hydraulic servo drive device for driving a swing mechanism of a variable geometry turbocharger includes a servo piston connected to a driveshaft of the swing mechanism and a pilot spool that is accommodated in a center hole of the servo piston and slides by pilot pressure. A first hydraulic chamber to and from which pressure oil flows are provided in a housing. The servo piston separately includes a pressure port for introducing pressure oil from an outside, a first piston port for intercommunicating the center hole and the first hydraulic chamber, a second piston port for intercommunicating the center hole and the second hydraulic chamber, and a return port for exiting pressure oil.

Variable turbo supercharger and method of driving the same

A hydraulic servo drive device for driving a slide mechanism of a variable geometry turbocharger includes a servo piston connected to a driveshaft of the slide mechanism and a pilot spool that is accommodated in a center hole of the servo piton and slides by pilot pressure. A first hydraulic chamber and a second hydraulic chamber to and from which pressure oil flows are provided in a housing. The servo piston separately includes a pressure port for introducing pressure oil from an outside, a first piston port for intercommunicating the center hole and the first hydraulic chamber, a second piston port for intercommunicating the center hole and the second hydraulic chamber, and a return port for exiting pressure oil.

An EGR valve device includes a valve housing of which inside exhaust gas passes through, a poppet valve as a valve body accommodated in the valve housing, and a hydraulic servo actuator for driving the poppet valve to be opened and closed. The hydraulic servo actuator is provided by a three-port or four-port servo valve.

EGR valve device

Provided are a variable geometry turbocharger in which a drain pipe from a hydraulic servo drive device can be omitted and in which a member for transmitting power of the hydraulic servo drive device can be efficiently lubricated, and a method of returning oil from the hydraulic servo drive device. The variable geometry turbocharger includes a slide mechanism for changing an opening degree of a nozzle, the hydraulic servo drive device for driving the slide mechanism by hydraulic pressure, and drain flow paths for delivering oil exhausted from the hydraulic servo drive device into an oil return chamber adjacent to a turbocharger body.

Variable turbo supercharger and method of returning oil from hydraulic drive

A rotor and a seat mounted on a first shell is disposed between an annular first shell and an annular second shell both constituting a damper case, thereby forming a rotary damper device. A damper lever on which the rotor is mounted is hooked on a fixing pin fixed to a body. Viscous fluid such as highly viscous oil is charged into a damper chamber formed between the rotor and the seat, and a viscous resistance is applied to the rotor and the seat. In a state in which a rotation center of the rotary damper device is deviated from a rotation center of the shaft which is rotated by the operating lever, the damper case is fixed to a flange portion of the shaft, the rotor and the seat are allowed to rotate relatively to each other by an inclining operation of the operating lever, and a resistance force from the rotary damper device is applied to the operating lever.

Operating lever device

A travel vibration suppressing deviceis structured such that a directional control valvefor a bucket, a directional control valvefor a boom, a ride control valveand a boom speed increasing valveare integrally arranged in a laminated manner by an internal piping. The ride control valvecommunicates or cuts off a bottom chamberof a boom cylinderand an accumulator. The boom speed increasing valvesupplies a discharge pressure of a hydraulic pumpto the bottom chamberor a head chamberor connects the to the bottom chamberor the head chamberto a tank

Travel vibration suppressing device for working vehicle

A rotary pilot valve in which a force required to operate the pilot valve is reduced and especially the pilot valve can be operated with a very small operating force as in a fingertip type, and the number of parts forming the pilot valve is reduced. In a body, a tank port, a pair of pump ports, a first output port, and a second output port are formed. In a cylindrical valve, a pair of notch grooves is formed and connected with each other by a balance hole. Variable throttles are formed on a side of the tank port and a side of the pump port of the notch groove. An open area of one of the variable throttles gradually increases while an open area of the other gradually reduces by tilting of an operating lever. Pressure oil lead into the notch groove through the variable throttle is output from the first output port as an intermediate throttle pressure.

Growing community of inventors

Oyama, Japan

Daisuke Kozuka