Hitachi Construction Machinery Co., Ltd.

Mitsuo Sonoda

Morio Oshina

Masatoshi Hoshino

Takashi Kanai

Hidetoshi Satake

Manabu Edamura

Seiji Ishida

Shinji Ishihara

Kazuo Fujishima

Masami Ochiai

Shinya Imura

Seiji Hijikata

Shiro Yamaoka

Takatoshi Ooki

Yusuke Kajita

Takashi Okada

Tsutomu Udagawa

Takenori Hiroki

Eiji Egawa

Akira Nakayama

Manabu Sugiura

Junji Yamamoto

Koji Nozaki

He Bao

Junji Tsumura

In a control device for construction machinery, a system operating point calculation unit calculates a plurality of combinations of engine rotational speed and engine torque with which demanded power of an engine can be generated; and calculates system efficiency in each of the combinations according to discharge pressure of a hydraulic. A rotational speed calculation unit calculates target rotational speed of the engine as the engine rotational speed in one of the combinations of the engine rotational speed, the engine torque and the system efficiency calculated by the system operating point calculation unit that includes desired system efficiency. A displacement calculation unit calculates target displacement of the hydraulic pump based on the target rotational speed calculated by the rotational speed calculation unit and demanded flow rate of the hydraulic pump. With this control device, the engine and the hydraulic pump can be controlled at an efficient operating point.

Device for controlling construction machinery

A hydraulic working machine has an assist electric motor connected to an engine and a hydraulic pump. The emissions of air pollutants in the exhaust gas from the engine are minimized regardless of fluctuations in the load torque of the hydraulic pump. A specific revolution speed suitable for reducing the emissions of air pollutants is stored, and an engine is controlled using the specific revolution speed as a target revolution speed. The absorption torque of a hydraulic pump is subjected to high-pass filtering whereby a high-frequency component devoid of a trend component is obtained. Target assist torque is computed from the high-frequency component, and the assist electric motor is subjected to power running/generation control accordingly. A specific output torque range suitable for reducing the emissions of air pollutants is stored, and the target assist torque is corrected so that the trend component does not exceed the specific output torque range.

Hydraulic working machine

To automatically prevent a reverse movement by inhibiting an excessive increase in an output torque of an electric motor. A means () calculates a target value for a rotation speed based on a command from a system (), a means () calculates a deviation between a detection value from a rotation speed sensor () and the target value, a means () calculates a first target torque in a direction that the deviation will be eliminated, and a means () calculates, based on a command from the system (), a second target torque in the same direction as the target value. A means () calculates a variation in a rotation angle of an electric motor () in a first range, and a means () calculates the same variation in a second range. A means () calculates, based on the variations from the means (), a third target torque in a direction that the rotation angle will return to a rotation angle before a predetermined time (t), and a means () limits the first target torque to one of the second and third target torques, said one target torque being in the same direction as the first target torque and being greater in absolute value. Substantially an entirety of the first range specifies a range for the variation in one direction, a remaining small range specifies a range for the variation in the other direction, substantially an entirety of the second range specifies a range for the variation in the other direction, and a remaining small range specifies a range for the variation in the one direction.

Rotation control device of working machine

In a hybrid construction machine, there is provided a drive control device which realizes in, as a simple a structure as possible, control means of a motor generator, which is capable of preventing rapid decreases in the state of charge. The control means, which calculates a motor torque command value to be output to the motor generator, is characterized by calculating the motor torque command value, based on a difference between an actual state-of-charge and a prescribed target state-of-charge and a torque margin obtained by a difference between a maximum torque of an engine determined based on an actual rotational speed of the engine and an actual torque of the engine.

Hybrid construction machine

A motive power regeneration apparatus for a working machine includes a regeneration circuit that is connected to a hydraulic line through which a returning fluid of a boom cylinder is distributed during a boom lowering operation. Also included are a hydraulic motor connected to a generator, a flow regulating circuit that is connected to the hydraulic line and provided with a control valve, an inverter that controls the flow rate on the regeneration circuit in accordance with a first flow rate setting which varies with the operation amount of an operating apparatus, and a control valve and a proportional valve that control the flow rate on the flow regulating circuit in accordance with a second flow rate setting which varies with the operation amount of the operating apparatus. Therefore, the motive power regeneration apparatus is capable of making an operator constantly feel comfortable with the working machine operations.

Motive power regeneration system for working machine

Operation control device for three-joint type excavator

A first hydraulic circuit comprises a variable displacement hydraulic pump driven by a prime mover, a variable displacement hydraulic motor connected in a closed circuit to the variable displacement hydraulic pump, and a displacement control means for controlling a displacement of the variable displacement hydraulic motor. A second hydraulic circuit comprises a hydraulic pump driven by the prime mover, and drives a loader attachment. A displacement limitation means limits the maximum value of the displacement of the variable displacement hydraulic motor in accordance with a load pressure of the second hydraulic circuit. For example, the displacement limitation means reduces the maximum value of the displacement of the variable displacement hydraulic motor in proportion to the pressure in the second hydraulic circuit. The motor torque is controlled by directly adjusting the displacement of the motor, and a load of the hydraulic motor can thus be stably controlled.

Hydraulic driving circuit with motor displacement limitation control

A hydraulic drive system is equipped with an engine, a plurality of hydraulic pumps adapted to be driven by the engine and including a variable displacement hydraulic pump provided with a displacement varying mechanism, a hydraulic motor connected to the variable displacement pump, a hydraulic actuator for actuating the displacement varying mechanism of the variable displacement hydraulic pump, a working fluid feeding means for feeding the hydraulic actuator with a hydraulic fluid of a pressure according to the degree of control of an accelerator lever which is adapted to instruct a target revolution number of the engine, and a low-pressure circuit for allowing the hydraulic fluid to be discharged therethrough from the hydraulic actuator. The system is provided with a maximum pressure limiting means for guiding the hydraulic fluid of the hydraulic fluid feeding means to the low-pressure circuit depending on the degree of control of the accelerator lever, thereby limiting the maximum pressure of the hydraulic fluid and a means for selectively actuating the maximum pressure limiting means.

Hydraulic drive system

A hydraulic drive circuit system is equipped with an accelerator pedal and an accelerator lever for respectively instructing target revolution numbers for an engine, a link plate for selecting greater one of the instruction values, and a linkage and a switch for controlling valves respectively so as to close the flow passage of a line interposed between a charge pump and a low pressure line irrespective of the instruction value of the accelerator pedal when the accelerator lever has not been controlled but for controlling the valves so as to restrict the flow passage of the line in accordance with the instruction value of the accelerator pedal when the accelerator lever has been controlled.

Hydraulic drive circuit system

Growing community of inventors

Kasumigaura, Japan

Mitsuo Sonoda