Hitachi Construction Machinery Co., Ltd.

Masafumi Hita

Shinya Imura

Hiroaki Amano

Shinji Nishikawa

Seiji Ishida

Ken Takeuchi

Hidekazu Moriki

Shinji Ishihara

Kouichi Shibata

Itaru Naya

Shiho Izumi

Yasuhiko Kanari

Shinichi Uotsu

Ryouhei Yamashita

Chiaki Takahashi

A controller that controls a dump truck in such a manner that the dump truck travels on a travelling route and stops at a loading specified position is provided in the dump truck. The controller computes, from travelling route data, a front-rear direction (a first stop direction) of the dump truck in a case in which the dump truck has travelled on the travelling route and stopped at the loading specified position, and corrects the travelling route to compute a post-correction travelling route including the loading specified position as an end point in such a manner that an excavator is located on an extension line of the front-rear direction (a second stop direction) of the dump truck in a case in which the dump truck has travelled on the post-correction travelling route and stopped at the loading specified position, on the basis of the computed first stop direction, position data of the loading specified position, and swing center position data of the excavator.

Control system of dump truck

When a machine-control ON/OFF switch is switched to the ON position, a controller outputs either a first control signal generated by an operation lever or a second control signal that operates a boom cylinder in accordance with a predetermined condition; when the ON/OFF switch is switched to the OFF position, the controller outputs the first control signal; when a control signal has been switched from one of the first control signal and the second control signal to the other control signal by the operation of the ON/OFF switch, the controller applies a rate limit to the control signal, and controls the boom cylinder on the basis of the control signal obtained after the limitation.

Work machine

A main controller and a hybrid controller control an engine, an assist generator motor, a hydraulic pump and an electricity storage device. In this case, the hybrid controller is provided with a performance state recovery part that performs performance state recovery of the electricity storage device. In a case where a performance state amount varying with repetition of a discharge and a charge of the electricity storage device, specifically, a current integrated value ratio of the electricity storage device goes beyond a predetermined threshold value (L1%), the performance state recovery part limits power of the hydraulic pump. Thereby, the performance state recovery part performs the performance state recovery of the electricity storage device.

Construction machine

An HCU () includes a battery low temperature reducing output calculating section (A) that determines, when it is determined that an electricity storage device () is in a low temperature state by a battery temperature Tb, a battery low temperature reducing output PbL that is made to a larger value as the battery temperature Tb is lower, a hydraulic oil low temperature reducing output calculating section (B) that determines, when it is determined that hydraulic oil is in a low temperature state by a hydraulic oil temperature To, a hydraulic oil low temperature reducing output PoL that is made to a larger value as the hydraulic oil temperature To is lower, and an output command calculating section () that controls a vehicle body operation based upon a sum of the battery low temperature reducing output PbL and the hydraulic oil low temperature reducing output PoL.

Hybrid construction machine

A work machine includes directional control valvesandeach controlling a direction and a flow rate of a pressurized fluid supplied to each a boom cylinderand a bucket cylinderoperation amount sensorsanddetecting operation amounts of operation devicesanda variable flow control valvethat can restrict the flow rate of the pressurized fluid in a meter-in passage of the directional control valverelated to the bucket cylinderand a controllercontrolling the variable flow control valve on the basis of the detection results by the operation amounts from the operation amount sensors, and the controller changes over an action mode to any one of a normal mode for restricting the flow rate of the pressurized fluid by the variable flow control valve and a responsiveness priority mode for not restricting the flow rate of the pressurized fluid by the variable flow control valve in response to the detection results of the operation amounts of the plurality of operation devices. It is thereby possible to enhance responsiveness in an action that requires responsiveness such as an action in which an operation amount of an operation lever frequently changes in a short period of time and to suppress a decline in work efficiency.

It becomes possible to prevent deterioration of an electric storage device due to overdischarge of the electric storage device and engine stalling due to insufficient assist or disabled assist when a charge amount of the electric storage device falls, ensure that work is continuously conducted, suppress an operator from feeling discomfort in operation, and ensure favorable operability. A pump target output power computing section () computes present pump demanded power on the basis of work related information, limits the present pump demanded power in response to a degree of reduction of a state of charge of an electric storage device () when the state of charge is lower than a preset threshold, and computes the limited present pump demanded power as present pump target output power. A pump flow rate limiting command value computing section () computes a pump flow rate limiting command value on the basis of the present pump target output power in such a manner that output power of a hydraulic pump () does not exceed the pump target output power.

The invention provides a work machine that achieves high accuracy of forming a target construction surface and reduced fuel consumption. A trajectory corrective Pi pressure calculation section calculates a trajectory corrective pressure, which is a control signal for a boom cylinder, based on the distance from a front work device to a target construction surface such that the motion trajectory of the work device is maintained above the target construction surface. A power corrective Pi pressure calculation section calculates a power corrective pressure, which is a control signal for the boom cylinder, based on the bottom pressure of an arm cylinder when the difference between the target power and actual power of the arm cylinder is larger than a predetermined output power value. The boom cylinder is controlled based on the larger of the power corrective pressure and the trajectory corrective pressure while the arm cylinder is being operated.

Construction work machine with corrective power control

A hybrid work machine that can suppress excessive limiting on pump absorption power even in a situation in which supply of electric power to an electric motor is limited is provided. The hybrid work machine includes: an enginean assist generator motorconnected to the enginein such a manner that a torque can be transmitted to the enginean electric storage devicethat supplies electric power to the assist generator motora monitoring devicethat monitors the electric storage deviceand that acquires electric storage device information; a hydraulic pumpdriven by the engineand the assist generator motorand a pump regulatorthat regulates a delivery flow rate of the hydraulic pumpThe hybrid work machine includes: an increasing rate computing sectionthat computes an allowable increasing rate r in response to the electric storage device information for pump absorption power; a limited power computing sectionthat computes a limited value WPlim of the pump absorption power on the basis of the allowable increasing rate r; and a pump control sectionthat controls the delivery flow rate of the hydraulic pumpin response to the limited pump power WPlim.

Hybrid work machine

A control system for a construction machine maintains operability of a swing combined operation even when the power supplied from an engine or storage device varies. The control system includes a target path computation section that receives an operation amount of the front implement operation device, an operation amount of the swing operation device, a speed of the front implement drive unit detected, and an angular speed of the swing structure drive unit, and that computes a target path of a claw tip position of the front implement drive unit; and an actuator power computation section that regulates power supplied to the front implement drive unit or the swing structure drive unit in such a manner that a claw tip of the front implement drive unit follows the target path the front implement operation device and the swing operation device are operated simultaneously.

Control system for construction machine

A motor-generator () is connected mechanically to an engine () and a hydraulic pump (). The hydraulic pump () delivers pressurized oil to cylinders (D) to (F) in a working mechanism (), a traveling hydraulic motor () and a revolving hydraulic motor (). The revolving hydraulic motor () drives a revolving device () in cooperation with a revolving electric motor (). An HCU () reduces outputs of the revolving electric motor (), the revolving hydraulic motor (), the boom cylinder (D) and the like such that a ratio of a revolving speed of an upper revolving structure () and a movement speed of raising a boom (A) is held to a ratio in a normal mode (NMODE) at the time of performing a compound movement of a revolving movement and a boom-raising movement in a low speed mode (LSMODE).

The lifetime of an electrical storage device is prolonged by reducing a speed of at least relevant one of hydraulic actuators for a specific operation to be performed by a work machine. This hybrid work machine includes a limit control section. When at least one specific operation defined as predetermined one or more among a plurality of work operations performed by the hybrid work machine is performed under condition of a degree of tendency to deterioration of the electrical storage device becoming higher, the limit control section reduces a speed of at least relevant one of the hydraulic actuators at a rate preset for the specific operation depending on the degree of tendency to deterioration of the electrical storage device.

An output command calculating section () of an HCU () restricts a battery discharge power from an electricity storage device () based upon a battery electricity storage rate (SOC) and a current square integrating rate (Risc) of the electricity storage device (). Thereby, the HCU () transfers from a normal mode (NMODE) to a low speed mode (LSMODE) to lower a movement speed of a hydraulic actuator. A monitor display amount calculating section () of the HCU () calculates a maximum speed reduction rate (DRs) based upon a battery discharge power limit value (Plim) and an engine output upper limit value (Pemax) from the output command calculating section (). A monitor device () displays a reduction rate of the movement speed of the hydraulic actuator in the low speed mode (LSMODE) based on the maximum speed reduction rate (DRs).

A motor generator () is connected mechanically to an engine () and a hydraulic pump (). The hydraulic pump () delivers pressurized oil to cylinders (D) to (F) in a working mechanism (), a traveling hydraulic motor () and a revolving hydraulic motor (). The revolving hydraulic motor () drives a revolving device () in cooperation with a revolving electric motor (). The motor generator () and the revolving electric motor () are connected electrically to an electricity storage device (). An HCU () sets a target electricity storage rate (SOC) of the electricity storage device () and a pump output limit (POL) of the hydraulic pump () corresponding to a mode selected by a mode selection device (). The HCU () controls the engine (), the motor generator (), the revolving electric motor () and the electricity storage device () corresponding to the target electricity storage rate (SOC) and the pump output limit (POL).

A hybrid work machine includes a controller and a temperature sensor that detects an electric storage device temperature. In a case where (Tp+Tc)&#x2265;Te_min, the controller carries out a first comparison in which the controller compares a value of [(Tp+Tc)&#x2212;Te_min] with a value of Ta_SOC, and the controller then selects a lower value of the first comparison. The controller then carries out a second comparison in which the controller compares the selected lower value of the first comparison with a value of [(Tp+Tc)&#x2212;Te_max)]. The controller then sets a higher value of the second comparison as the torque of the assist motor Ta, wherein Tc is an accessory torque, Ta_SOC is an adjustment assist motor torque based on a current state of charge of the electric storage device, Ta is the torque of the assist motor, and Te_max is an engine maximum torque.

A control device of construction machine that performs tasks by driving a hydraulic pump by means of an electric motor that is driven by electric power of a battery device that is capable to charge and discharge and an engine that is mechanically coupled to the electric motor, includes: a charging/discharging control unit that controls the charging/discharging of the battery device in such a manner that, in case that a heavy load task where an output of the hydraulic pump is large and a light load task where the output of the hydraulic pump is small are alternately performed, when the output of the hydraulic pump during the heavy load task is increased or a time proportion of the heavy load task in the unit period is increased, an average value of charging current of the battery device per the unit period increases, and when the output of the hydraulic pump during the heavy load task is further increased or the time proportion of the heavy load task in the unit period is further increased, then the average value of the charging current of the battery device per the unit period decreases.

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Tsuchiura, Japan

Masafumi Hita