Kawasaki Jukogyo Kabushiki Kaisha

Kabushiki Kaisha Kcm

Kazuto Fujiyama

Akihiro Kondo

Makoto Ito

Hideyasu Muraoka

Ryo Yamamoto

Toyoaki Sagawa

Masahiro Yamada

Hideki Tanaka

Shinichiro Tanaka

Hiroyasu Kodera

Yoshio Togashi

Shinji Narita

Kazuya Matsumoto

Kimihiko Murase

Koji Sakashita

A spool valve capable of suppressing deterioration of position controllability of a spool due to misalignment includes: a housing including a spool hole; a spool inserted into the spool hole of the housing so as to be movable in an axial direction; and an electric actuator configured to move the spool in the axial direction. The electric actuator includes: an electric motor configured to rotate an output shaft; a linear-motion converting mechanism including a linear-motion member configured to be linearly movable, the linear-motion converting mechanism being configured to convert a rotational motion of the output shaft into a linear motion of the linear-motion member; and a coupling member coupling the linear-motion member and the spool moves in accordance with the linear motion of the linear-motion member. The coupling member allows one of tilt and eccentricity of an axis of the spool relative to an axis of the linear-motion member.

Spool valve

A hydraulic excavator drive system includes: first and second pumps; arm cylinder; arm first control valve connected to the cylinder by an arm crowding supply line and arm pushing supply line; arm second control valve connected to the supply lines by a first and second replenishment line; and arm operation device that outputs an operation signal corresponding to an inclination angle of an operating lever. The arm second control valve is configured so, when performing an arm crowding operation, an opening area at a meter-in side changes in accordance with the operation signal, and an opening area at a meter-out side is: kept to zero when a predetermined condition is not satisfied; and kept to zero until the operation signal becomes a setting value or greater, and when the operation signal has become the setting value or greater, increases to a maximum value when the predetermined condition is satisfied.

Hydraulic excavator drive system

A fluid pressure system includes an actuator, an operating valve, and a spool valve. The spool valve is connected to a pressure source and a tank by a pressure source line and a tank line, respectively, and connected to the actuator by a first movement line and a second movement line. The spool valve moves from a neutral position to a movement position by a moving amount corresponding to a pilot pressure outputted from the operating valve, the movement position being a position at which the spool valve allows the pressure source line to communicate with the first movement line and allows the second movement line to communicate with the tank line. A relief line branches off from the second movement line, and the relief line connects to a tank. A variable throttle valve is provided on the relief line.

Fluid pressure system

A hydraulic excavator drive system includes: a cylinder that drives a moving part that is an arm or a bucket. Hydraulic oil is supplied from a hydraulic pump to the cylinder via a control valve. A bypass line branches off from a rod-side supply/discharge line. The bypass line is blocked and opened by a restrictor. The restrictor is controlled by a controller such that, when the hydraulic oil is supplied to the cylinder through a head-side supply/discharge line, the restrictor blocks the bypass line if a pressure detected by a load detector is lower than a predetermined value, and opens the bypass line if the pressure detected by the load detector is higher than or equal to the predetermined value.

A tilting angle control device includes pressure sensors. Each of the pressure sensors outputs to a control unit a pressure command signal corresponding to an operation amount. The control unit outputs to an electromagnetic proportional control valve a pressure control signal corresponding to the pressure command signal, and the electromagnetic proportional control valve outputs to a tilt adjustment mechanism pilot pressure corresponding to the pressure control signal. The tilt adjustment mechanism adjusts a tilting angle of a variable displacement pump such that the tilting angle becomes an angle corresponding to the pilot pressure. A pilot pressure sensor detects the pilot pressure to output a pressure feedback signal to the control unit. The control unit calculates the pressure control signal based on the pressure feedback signal and the pressure command signal and performs feedback control of the pilot pressure.

Tilting angle control device

A hydraulic driving system includes first to third liquid-pressure pumps and control valves. The first boom control valve is connected to the first hydraulic pump, and the second arm control valve and the first bucket control valve are connected to the second liquid-pressure pump. Further, the turning control valve and the second bucket control valve are connected to the third hydraulic pump. When a pilot pressure XAkis output from a bucket operating device while a turning operation is performed, a command switching device outputs a pilot pressure XAkto the first bucket control valve. When the pilot pressure XAkis output from the bucket operating device while the turning operation is performed, the command switching device outputs a pilot pressure XAkto a second bucket control valve.

Liquid-pressure driving system

A hydraulic excavator drive system includes: a first hydraulic pump and a second hydraulic pump, whose respective tilting angles are controllable independently of each other; an arm main control valve and an arm auxiliary control valve each for controlling supply of hydraulic oil to an arm cylinder; and a boom main control valve and a boom auxiliary control valve each for controlling supply of the hydraulic oil to a boom cylinder. An arm operation valve outputs a pilot pressure to the arm main control valve. A boom operation valve outputs a pilot pressure to the boom main control valve. A pair of arm-side regulating valves outputs no pilot pressure to the arm auxiliary control valve and a boom-side regulating valve outputs no pilot pressure to the boom auxiliary control valve when an arm crowding operation and a boom raising operation are performed concurrently.

A hydraulic control device includes: a hydraulic pump connected in parallel to steering and boom cylinders; a steering control valve that controls the direction of operating oil flowing through the steering cylinders; a boom control valve that connects the hydraulic pump to a tank when the valve is at a neutral position and controls the direction of the oil flowing through the boom cylinders when the valve is at an offset position; a meter-in pressure compensator that increases flow rate of the oil flowing through a variable restrictor of the steering control valve in accordance with pressure in front of and behind the restrictor; and a bleed-off pressure compensator that decreases flow rate of the oil flowing through the boom control valve in accordance with the increase in pressure of the oil flowing through the steering cylinders to maintain the predetermined pressure of the oil in the steering control circuit.

Hydraulic control device and construction machinery including same

The present invention intends to improve a hydraulic control unit and prevent the occurrence of hunting as well as to reduce the size of the hydraulic control unit. The hydraulic control unit is used in a several-directional-control-valves-assembled-type hydraulic control system 1 having a load sensing function. The hydraulic control unit has a PLS port. The PLS port is supplied with a maximum load pressure in the hydraulic control system. The compensator of the hydraulic control unit includes a metering orifice imparted with a function equivalent to a check valve. The compensator is imparted with the function of a shuttle valve (directional control valve), and by allowing the shuttle valve to operate independently of the compensator the pressure PLS is adjusted constantly.

Hydraulic controller

In order to obtain great damper effects with a comparatively simple structure and fully control a hunting phenomenon, a pilot valve comprises push rods attached to a valve body, spools attached to spools holes of the valve body, spring bearing members provided in spring chambers of the valve body, first spring members provided between the valve body and the spring bearing members, second spring members provided between the spring bearing members and the spools, and an operation level for pressing the push rods. A fluid chamber is provided on an outside of one of ends of each of the spool holes. The fluid chamber communicates with a drain passage through a throttle passage having a throttle portion.

Growing community of inventors

Kobe, Japan

Kazuto Fujiyama