Hitachi Construction Machinery Co., Ltd.

Hiromasa Takahashi

Kenji Hiraku

Juri Shimizu

Teppei Saitoh

Shohei Sugiki

Yuki Akiyama

Takamasa Kai

Teppei Saitou

Akinori Ishii

Mariko Mizuochi

Shouhei Sugiki

Kazuo Takiguchi

Jun Okamura

Takashi Kusama

Yoshifumi Takimoto

Chinori Iio

Syouhei Sugiki

Hiraku Kenji

A construction machine makes it possible for an operator to linearly push a bucket by operating an arm in a pushing direction. A controller is configured to, in case a straight locus is selected by a bucket locus selecting device, calculate a constant flow rate ratio according to a boom initial angle that is an angle of a boom sensed by a boom angle sensor at a time point when an arm is operated in a pushing direction by an operation device, and control the delivery flow rate of a first hydraulic pump such that a hydraulic fluid is discharged from a boom cylinder cap chamber at a flow rate obtained by multiplying a flow rate of a flow supplied to an arm cylinder cap chamber by the flow rate ratio while the arm is operated in the pushing direction and there is no boom operating instruction.

Construction machine

Provided is a construction machine in which travel operability is not impaired when a combined operation is performed in which a single-rod hydraulic cylinder is driven during a travel operation. A hydraulic excavator includes a controller that controls the delivery direction and delivery flow rate of a closed-circuit pump, opens and closes a travel switching valve and an assist switching valve, and controls the delivery flow rate of the open-circuit pump, according to a travel operation lever and a work operation lever. The controller holds the assist switching valve in a closed position irrespective of whether or not the work operation lever is operated in a case where the travel operation lever is operated.

Provided is a construction machine on which a hydraulic closed circuit for driving a single rod-type hydraulic cylinder and a swing hydraulic motor is mounted and that has good swing deceleration responsiveness. In this construction machine that drives each of a single rod-type hydraulic cylinder and a swing hydraulic motor in a closed circuit, a minimum passage area from a second flushing valve to a tank in a case the second flushing valve is fully open is smaller than a minimum passage area from a first flushing valve to the tank in a case the first flushing valve is fully open.

To provide a construction machine that has a hydraulic system mounted thereon in which a closed-circuit pump, and an open-circuit pump and a proportional valve are arranged as a pair, and that makes it possible to use an unused open-circuit pump or proportional valve to accelerate the speed of a single rod hydraulic cylinder when the single rod hydraulic cylinder and a hydraulic motor are driven simultaneously. A controller () controls a cap-side selector valve () and a rod-side selector valve () such that a particular open-circuit pump () not connected to a single rod hydraulic cylinder () is connected to the single rod hydraulic cylinder, and controls an opening area of a particular proportional valve () provided on a flow line that connects a delivery port of the particular open-circuit pump to a tank, when the single rod hydraulic cylinder and a hydraulic motor () are driven simultaneously.

To make it possible to prevent a decrease in work speed due to a decrease in the speed of a given actuator when an operator unintentionally performs a fine operation of the control lever of the other actuator in a state in which the given actuator is driven by the hydraulic fluid delivered from a plurality of pumps, a controller () sets, as a composite dead zone line serving as a boundary of a composite dead zone, a composite dead zone line such that as an operation amount in one direction of a control lever (L) or (L) of a control lever device () or () is increased, the width of the composite dead zone corresponding to an operation amount in the other direction of the control lever is widened, and corrects the operation amount in the other direction such that the demanded flow rate of an actuator increases from zero, when the control lever is operated in the other direction in a state in which the operation amount in the one direction of the control lever remains within a range of the composite dead zone, and the operation amount in the other direction exceeds the composite dead zone line.

An object of the present invention is to provide a construction machine capable of suppressing lugging down of an engine irrespective of contents of operation of an operator and the load state of a hydraulic actuator. A controllerincludes: a demanded torque estimating sectionconfigured to estimate demanded torque as torque demanded from an engineby the first hydraulic pump on the basis of a demanded velocity of a first hydraulic actuatorand a load pressure on the first hydraulic actuator; a demanded velocity limiting sectionconfigured to, in a case in which a demanded torque change rate as a change rate of the demanded torque exceeds a predetermined change rate, limit the demanded velocity such that the demanded torque change rate becomes equal to or lower than the predetermined change rate; and a command calculating sectionconfigured to calculate a delivery flow rate of the first hydraulic pump on the basis of the demanded velocity of the first hydraulic actuator, the demanded velocity being limited by the demanded velocity limiting section.

An object of the present invention is to provide a construction machine that has a hydraulic closed-circuit system mounted therein and capable of selectively connecting some of a plurality of hydraulic pumps driven by two engines to any one of a plurality of hydraulic actuators and that can downsize the engines while maintaining high work efficiency. A controllerincludes an actuator/engine allocation computing section Fthat, at the time of connecting closed-circuit pumps that are not connected to any of the hydraulic actuators, andto any one of the hydraulic actuators, allocates closed-circuit pumps driven by a right engineto the one hydraulic actuator in a case in which an estimated maximum load on a left engineis heavier than an estimated maximum load on the right engine, and allocates closed-circuit pumps driven by the left engine to the one hydraulic actuator in a case in which the estimated maximum load on the right engine is heavier than the estimated maximum load on the left engine.

A construction machine incorporates a hydraulic closed circuit system capable of suppressing, even where a selector valve is stuck in an open state by a failure of the selector valve or a control system therefor, unintended operation of a hydraulic actuator and continuing operation of a machine body. The construction machine includes first sensors that detect open-closed states of a plurality of switching valves, first compulsory valve closing devices that change over the plurality of switching valves to a closed position irrespective of open-close control by a machine body controller, and a valve device controller that controls, when it is detected based on the open-closed states of the plurality of selector values detected by the first sensors that one of the plurality of selector values is stuck in an open state, the first compulsory valve closing device such that other selector valve connected to one of the plurality of closed circuit pumps to which the one selector valve is connected is closed.

There is provided a hydraulic drive device for a working machine with which a number of times of maintenance can be reduced. A controller () opens a first on-off valve (), closes a second on-off valve (), switches a first directional switching valve () to a first position (A), and switches a second directional switching valve () to a third position (C), thereby pressure oil from a hydraulic pump () is supplied from the first on-off valve to an actuator () through the first directional switching valve. When history data of the first on-off valve is determined to satisfy a prescribed condition, the controller closes the first on-off valve, opens the second on-off valve, switches the first directional switching valve to a second position (B), and switches the second directional switching valve to a fourth position (D), thereby pressure oil from the hydraulic pump is supplied from the second on-off valve to the actuator through the second directional switching valve. For example, the controller determines that the prescribed condition is satisfied when an operation number of times of the first on-off valve reaches a first prescribed value.

Hydraulic drive device for working machine

Provided is a work machine that can selectively establish a closed circuit connection between a single rod-type hydraulic cylinder and a plurality of bidirectional-type hydraulic pumps, the work machine being capable of enhancing responsiveness of the single rod-type hydraulic cylinder when a high-speed lever switching operation is conducted in a state in which a rod pressure of the single rod-type hydraulic cylinder is higher than a bottom pressure. When a bucket lever () is operated to a side of extending the bucket cylinder in a state in which a pressure in a rod chamber () of the bucket cylinder () is higher than a pressure in a bottom chamber (), a controller () opens a rod-side proportional valve () and discharges a working fluid in the rod chamber to a working fluid tank () such that a differential pressure between the pressure in the rod chamber and the pressure in the bottom chamber is reduced below a switching pressure (Psw) of a flushing valve ().

Drive system for construction machine

A construction machine is provided which includes a hydraulic closed circuit in which a single rod hydraulic cylinder is driven directly by a bidirectionally tiltable variable displacement pump and can stably speed up the contraction action of the single rod hydraulic cylinder. In the case where a contraction action of a hydraulic cylinderis instructed through an operation leverwhen a differential pressure obtained by subtracting the pressure of a cap chamberfrom the pressure of a rod chamberis equal to or lower than a first threshold value a set to a level equal to or higher than a selection setting pressure of a flushing valvea controllercloses a rod side selector valveto disable rod assist action for supplying hydraulic fluid from a second hydraulic pumpto the rod chamber, and when the differential pressure is higher than the first threshold value, the controlleropens the rod side selector valve to enable the rod assist action.

This construction machine includes a first hydraulic drive device that is driven by a first prime mover and a second hydraulic drive device that is driven by a second prime mover. The first hydraulic drive device has a first closed circuit that connects a first hydraulic actuator and a first closed-circuit pump and a first assist flow path that connects the first closed circuit and a first open-circuit pump and that supplies pressure oil from the first open-circuit pump to the first closed circuit. The second hydraulic drive device is provided with a second closed circuit that connects a second hydraulic actuator and a second closed-circuit pump. The present invention also includes a first emergency flow path that branches from the first assist flow path and connects to the second closed circuit and that supplies pressure oil from the first open-circuit pump to the second closed circuit.

A construction machine includes a bidirectionally tiltable type hydraulic pump, a hydraulic cylinderhaving a cap chamberand a rod chamber, a first flow pathconnecting the hydraulic pumpand the cap chamber, a second flow pathconnecting the hydraulic pumpand the rod chamber, a discharge flow pathbranched from the first flow path, a discharge valvethat is disposed in the discharge flow pathand controls a discharge rate of hydraulic working oil from the cap chamberto the discharge flow path, an operation devicethat instructs an action of the hydraulic cylinder, and a controller. The controllercontrols the hydraulic pumpand the discharge valvesuch that at least a part of hydraulic working oil discharged from the cap chamberis discharged to the discharge flow pathwhen an operation amount of the operation devicelies within a fine operation region during a pulling action of the hydraulic cylinderin a state that a load is applied in a contraction direction. Accordingly, operability improves during fine operation of the pulling action of the hydraulic cylinder in the state that the load is applied in the contraction direction.

A work machine that can detect abnormality such as a malfunction and wear and tear of each of hydraulic pumps including control equipment with high precision and that can reduce equipment cost is provided. A controlleraccording to the present invention includes a volumetric-transfer-efficiency-calculating sectionthat calculates a volumetric transfer efficiency &#x3b7;representing a transfer efficiency of hydraulic oil between a hydraulic cylinderand hydraulic pumpstoon the basis of a target discharge flow rate calculated by a target-discharge-flow-rate-calculating sectionand the speed of the hydraulic cylinderthat is detected by a speed sensor, and an abnormality decision sectionthat decides whether any one of the hydraulic pumpstois abnormal on the basis of the volumetric transfer efficiency &#x3b7;calculated by the volumetric-transfer-efficiency-calculating section

Work machine

Provided is a construction machine capable of detecting a stuck-open state of a surplus flow control valve in real time during operation without involving a reduction in the operational speed. The construction machine is equipped with: a surplus flow control valve control section configured to output a closing command to a first surplus flow control valve at the operation start when an operation amount signal of an operation lever device is detected; a pump delivery control section configured to output a delivery flow rate command to an adjustment section of an open circuit pump; an assist valve control section configured to continue to output a closing command from before to an assist valve; a sticking detection determination section configured to compare a pressure signal with a previously set threshold value and determining that the surplus flow control valve is in a stuck-open state when the pressure signal is less than the threshold value and determining that the surplus flow control valve is normal when the pressure signal exceeds the threshold value; and a stop signal generating section configured to input therein a sticking determination signal, output in the case of a stuck-open state a control signal maintaining a closed state of the assist valve to the assist valve control section, and output in the case of a normal state a control signal causing the assist valve to perform an opening operation to the assist valve control section.

Growing community of inventors

Tsuchiura, Japan

Hiromasa Takahashi