Hitachi Construction Machinery Co., Ltd.

Hitachi, Ltd.

Renesas Technology Corp.

Kabushiki Kaisha Toyota Jidoshokki

Clarion Co

Hitachi Cable, Inc.

Hitachi Car Engineering Co., Ltd.

Xanavi Informatics Corporation

Kcm Corporation

Masatoshi Hoshino

Shinji Ishihara

Seiji Hijikata

Yasutaka Tsuruga

Kohei Sakurai

Kouji Ishikawa

Nobuyasu Kanekawa

Kiwamu Takahashi

Minoru Ohsuga

Yuichiro Morita

Hiroshi Sakamoto

Mitsuru Watabe

Yoshiaki Takahashi

Kenichi Kurosawa

Kotaro Shimamura

Kazuo Fujishima

Toshimichi Minowa

Shinya Imura

Shinya Sato

Manabu Edamura

Yasuhiro Nakatsuka

Kenji Hiraku

Shoji Sasaki

Yasushi Sasaki

Hidetoshi Satake

Nobuo Kurihara

Hidekazu Moriki

Yutaka Takaku

Yutaka Nishimura

Seiji Ishida

Shiro Yamaoka

Toshiharu Nogi

Hiroshi Kuroda

Satoru Kaneko

Hiromichi Yamada

Atsushi Yokoyama

Tatsuya Yoshida

Shinji Nishikawa

Masato Imai

Masao Sakata

Fumio Arakawa

Jun Kubo

Katsuji Marumoto

Kentarou Itoga

Ryou Yagisawa

Minoru Oosuga

Kentaro Yoshimura

Atsushi Kanke

Kunihiko Tsunedomi

Mitsuo Sonoda

Yuichi Ogawa

Ryozo Masaki

Yasuhiro Kamimura

Noriyoshi Urushiwara

Masahiro Matsubara

Takatoshi Ooki

Takashi Ikimi

Yasuhiro Gunji

Yoichi Iihoshi

Naoki Yada

Shigeru Oho

Yusuke Kajita

Shinjiro Saito

Masayoshi Kaneyasu

Takao Kojima

Takashi Okada

Masaaki Shimizu

Masahiko Amano

Minoru Osuga

Mikihiko Onari

Ken Naono

Takaomi Nishigaito

Toshiharu Sugawara

Noritaka Ito

Satoshi Tanaka

Akira Nakayama

Junji Yamamoto

Tsutomu Umehara

Tetsuya Ichihashi

Kazuhiro Komatsuzaki

Kenji Takano

Yoshimasa Nagashima

Shou Furukawa

Yuusuke Kajita

He Bao

Naoki Ishikawa

Provided is a work machine including a flow control valve serving as a flow control mechanism that controls a flow rate of pressurized fluid from a hydraulic pump to a hydraulic actuator via a first control valve. A controller of the work machine, when the pressurized fluid is supplied to the hydraulic actuator from only an accumulator, drives a second control valve such that a meter-in side of the hydraulic actuator and the accumulator are connected to each other, drives the first control valve such that a meter-out side of the hydraulic actuator and a tank are connected to each other, and drives the flow rate control mechanism such that a flow of the pressurized fluid from the hydraulic pump to the hydraulic actuator via the first control valve is interrupted.

Work machine

An object of the present invention is to provide a construction machine that is equipped with a pressure accumulating device, which accumulates the return oil of an actuator, and that is capable of adjusting the operation speed of the actuator according to the revolution speed of a prime mover. For this purpose, in a construction machine including a prime mover, a revolution speed setting device that sets a revolution speed of the prime mover, an actuator, a pressure accumulating device that can supply and discharge a hydraulic fluid to and from the actuator, a first control valve disposed on a hydraulic fluid line that connects the pressure accumulating device and the actuator to each other, an operation device that gives an instruction for operation of the actuator, and a controller that is inputted with an operation signal of the operation device and outputs a control signal to the first control valve, the controller controls the first control valve according to an operation amount of the operation device and the revolution speed set by the revolution speed setting device.

Construction machine

The object of the invention of the present application resides in provision of a work machine that can be improved in operability at start of an action of a hydraulic actuator in a fine operation in which an operation lever is operated by a small amount. To this end, on the basis of a signal from a first timing sensor and a signal from a second timing sensor, a machine body controller controls, before the first timing is sensed, the pump delivery flow rate to a minimum delivery flow rate, controls, after the first timing is sensed but before the second timing is sensed, the pump delivery flow rate to a predetermined delivery flow rate that is greater than the minimum delivery flow rate, and controls, after the second timing is sensed, the pump delivery flow rate to a delivery flow rate according to an operation amount of the operation lever.

The present invention provides a construction machine equipped with a pressure accumulation device that accumulates return oil from an actuator, and that can implement both improvement in fuel efficiency with enhancement in workability. To achieve the foregoing, a controller sets an actuator upper limit output power that is an upper limit for an output power of the actuator according to a work mode selected by a work mode selection device, and controls a first control valve and a second control valve such that a sum of an output power of a hydraulic pump and an output power of the pressure accumulation device does not exceed the actuator upper limit output power.

A work machine includes a hydraulic pump that is driven by an engine and delivers a pressurized fluid, a hydraulic actuator that is operated by the pressurized fluid delivered by the hydraulic pump, a hydraulic accumulator device that accumulates the pressurized fluid discharged from the hydraulic actuator, a differential pressure control valve that is disposed between the hydraulic actuator and the hydraulic accumulator device and generates a differential pressure across the differential pressure control valve between a pressure of the hydraulic actuator and a pressure of the hydraulic accumulator device, a pressure sensor that senses the pressure of the hydraulic accumulator device, and a controller that controls the differential pressure control valve on the basis of a sensing result of the pressure sensor. The controller controls the differential pressure control valve in such a manner that the differential pressure across the differential pressure control valve reduces according to a rise in the pressure of the hydraulic accumulator device sensed by the pressure sensor.

An object of the present invention is to provide a construction machine that can use the return oil from a hydraulic actuator effectively. For this purpose, a controller computes a flow rate of the return oil from a first hydraulic actuator on the basis of an operation signal from a first operation device, computes a flow rate of oil to be supplied to a second hydraulic actuator on the basis of an operation signal from a second operation device, sets smaller one of the flow rate of the return oil and the flow rate of the oil to be supplied, as a regeneration flow rate that is a flow rate of oil to be regenerated in the second hydraulic actuator, sets a flow rate obtained by subtracting the regeneration flow rate from the flow rate of the return oil, as a recovery flow rate that is a flow rate of oil to be recovered to a pressure accumulating device, adjusts an opening degree of a first control valvesuch that a flow rate of oil supplied from the first hydraulic actuator to the pressure accumulating device coincides with the recovery flow rate, and adjusts an opening degree of a second control valve such that a flow rate of oil supplied from the first hydraulic actuator to the second hydraulic actuator coincides with the regeneration flow rate.

It is an object of the present invention to provide a construction machine capable of efficiently driving a hydraulic cylinder by an accumulator. Thus, the construction machine includes a first control valve disposed in a first hydraulic fluid line connecting a bottom-side fluid chamber of a hydraulic cylinder with an accumulator, and a second control valve disposed in a second hydraulic fluid line connecting a rod-side fluid chamber of the hydraulic cylinder with a tank. The construction machine further includes a third control valve disposed in a third hydraulic fluid line connecting the rod-side fluid chamber with the accumulator, and a fourth control valve disposed in a fourth hydraulic fluid line connecting a line part of the first hydraulic fluid line, which connects the bottom-side fluid chamber with the third control valve, and a line part of the third hydraulic fluid line, which connects the rod-side fluid chamber with the third control valve, with each other.

The object of the present invention resides in provision of a construction machine in which a hydraulic cylinder can be driven in a high efficiency by an accumulator. To this end, the construction machine including: a hydraulic cylinder; a first accumulator that accumulates return fluid from the hydraulic cylinder with a first set pressure; a tank that stores hydraulic fluid therein; a first hydraulic pump that delivers the hydraulic fluid sucked from the tank; a hydraulic actuator that is driven by the first hydraulic pump; and a second accumulator that accumulates return fluid from the hydraulic actuator with a second set pressure, includes a first control valve placed in a first hydraulic line that connects the first accumulator and the hydraulic cylinder to each other, and a second control valve placed in a second hydraulic line that connects the second accumulator and the hydraulic cylinder to each other. The second set pressure is set to a value higher than that of the first set pressure.

Provided is a work machine capable of achieving both low fuel consumption and ensuring of workability. The work machine is configured to, in a state where an output of an engine or hydraulic pump has increased to an increase threshold (S: Yes) with the rotational speed being at a first rotational speed (S: Yes), raise the rotational speed from the first rotational speed to a second rotational speed (S); in a process of raising the rotational speed to the second rotational speed, output, to a regulator, a signal instructing reduction in the discharge rate (S) so as to keep the output of the engine or hydraulic pump constant; and after the rotational speed has reached the second rotational speed, output, to the regulator, a signal instructing increase in the discharge rate (S) so as to make the output of the engine or hydraulic pump have a value corresponding to a request load.

A work machine includes: a hydraulic actuator that is driven by a hydraulic fluid from a hydraulic pump; an open-center directional control valve that is arranged on a center bypass line, and controls a flow of the hydraulic fluid to be supplied to the hydraulic actuator; a CB cut valve arranged between a directional control valve and a hydraulic working fluid tank on the center bypass line; and a machine controller that controls an opening of the CB cut valve. The machine controller restricts the opening of the CB cut valve when operation on the hydraulic actuator is in a fine operation state in which the operation on the hydraulic actuator is within a predetermined range representing a region of fine operation, and the fine operation state is continued longer than a predetermined period, and fully opens the CB cut valve otherwise.

A first torque control proportional electromagnetic valve () is connected through a first torque control line () to a third pressure receiving chamber (D) in a first torque control regulator (). A second torque control proportional electromagnetic valve () is connected through a second torque control line () to a third pressure receiving chamber (D) in a second torque control regulator (). The first and second torque control proportional electromagnetic valves () are controlled by a controller. A switching valve () is provided between the first torque control line () and the second torque control line (). The switching valve () supplies an output pressure of the first torque control proportional electromagnetic valve () to the third pressure receiving chamber (D) in the second torque control regulator () at the time of driving hydraulic motors (B,C) for left side and right side traveling.

Hydraulic drive apparatus

A controller () is provided with an elapse time measuring section (A) that measures an elapse time (tx) elapsed since an initial use of an accumulator () based upon a reset signal from a reset switch (), a number-of-operations measuring section (B) that measures a number of operations of the accumulator (), that is, a number (N) of boom lowering operations after a reset, based upon a detection signal from an accumulator side pressure sensor (), a gas permeation amount estimating section (C) that estimates an estimation gas permeation amount (Qloss) of the accumulator (), a sealed gas pressure estimating section (D) that finds an estimation sealed gas pressure (Pgs) of a gas chamber (B) of the accumulator (), and an accumulator degradation determining section (E) that determines a degradation condition of the accumulator () and outputs the determination result.

Hydraulic energy recovery apparatus for working machine

To increase frequency of use of auto idle, an engine is accelerated even more quickly than before and work involving a heavy load can be performed within a short period of time when an operator resumes work and recovers a speed of the engine. When an operation lever device is operated and the speed is low because of auto idle control, a pilot pump is unloaded to thereby reduce load torque on the engine. Operation of a compressor is also suspended while an air conditioner is operating. Furthermore, for a target speed of the engine, a speed at which work can be performed is set and the engine is accelerated. When the engine thereafter reaches a predetermined speed or a predetermined period of time thereafter elapses, the pilot pump is loaded and the operation of the compressor for the air conditioner is resumed.

Hydraulic work machine

A hydraulic circuit () of a hydraulic excavator () is provided with a main hydraulic circuit (A) including a boom cylinder (D), a pilot hydraulic circuit (B) for operating the boom cylinder (D) and a recovery hydraulic circuit (C) including an accumulator (). In this case, the recovery hydraulic circuit (C) is provided with a recovery control valve () that recovers pressurized oil discharged from the boom cylinder (D) to the accumulator (), a main supply control valve () for supplying pressurized oil accumulated in the accumulator () to the main hydraulic circuit (A) and a pilot supply control valve () for supplying pressurized oil accumulated in the accumulator () to the pilot hydraulic circuit (B).

A work machine including: a hydraulic cylinderconfigured to drive a work implement; a control valveconfigured to connect a delivery line of a hydraulic pumpswitchingly to a bottom fluid chamber and a rod fluid chamber of the hydraulic cylinderand a tank; a pilot pumpconfigured to output a pilot pressure to drive the control valve; an engineconfigured to drive the hydraulic pumpand the pilot pump; and an accumulatorconfigured to accumulate a return hydraulic fluid from the hydraulic cylinderis provided with: a bypass lineconfigured to connect the bottom fluid chamber of the hydraulic cylinderand a delivery lineof the hydraulic pumpby bypassing the control valveand be provided with the accumulatorthereon; a pressure-accumulation control valveprovided between the bottom fluid chamber of the hydraulic cylinderand the accumulator; a release control valveprovided between the accumulatorand the delivery line; and a hydraulic system controllerconfigured to open the release control valveif an engine revolution speed N becomes lower than a set value Ns.

Growing community of inventors

Tsuchiura, Japan

Masatoshi Hoshino