Hitachi Construction Machinery Co., Ltd.

Zexel Gmbh

Yusuke Kajita

Genroku Sugiyama

Toichi Hirata

Kouji Ishikawa

Kazunori Nakamura

Hidetoshi Satake

Seiji Ishida

Hideaki Tanaka

Takatoshi Ooki

Hideo Karasawa

Manabu Edamura

Kazuo Fujishima

Shinya Imura

Hiroshi Watanabe

Shiho Izumi

Shiro Yamaoka

Masakazu Haga

Toshihiro Abe

Hiroshi Onoue

Rindo Morikawa

Yasuo Tanaka

Masatoshi Hoshino

Tsuyoshi Nakamura

Eiki Izumi

Takashi Okada

Yukio Aoyagi

Hiroyuki Azuma

Ei Takahashi

Masataka Sasaki

Kensuke Sato

Yasuo Okano

Gen Yasuda

Osamu Tomikawa

Mitsuo Sonoda

Mitsuhiko Kanehama

Akira Nakayama

Shigetaka Nakamura

Shinya Okumura

Kazuhiro Sunamura

Junji Yamamoto

Tomohiko Yasudi

Kiyoshi Oyama

He Bao

A construction machine including an internal combustion engine controlled based on a torque command, an electric motor mechanically connected to the internal combustion engine, and an electric energy storage device that supplies electric power to the electric motor, the construction machine performing work by driving a hydraulic pressure generator using the internal combustion engine and the electric motor, the construction machine including: a speed control device that controls a speed of the electric motor based on a speed command; and a torque limiter that limits the torque command relative to a torque target, wherein the torque command is limited by the torque limiter in such a manner that a rate of change with time of the torque command is limited to be equal to or less than a predetermined value.

Construction machine

Construction machine capable of incorporating an engine and using an external power source. The construction machine includes an electrical storage device performing a charge with the external power source, uses the electrical storage device to provide assist when the power of the engine is insufficient, uses an electrical charge in the electrical storage device systematically in accordance with work time, and efficiently uses the electrical storage device by controlling its discharge amount in accordance with load status. The construction machine includes the engine, accessory loads connected to the engine, an assist electric motor driven by the engine, electrical power converters for converting an AC current, which is the output current of the assist electric motor, to a DC current, and the electrical storage device connected to the DC side of each electrical power converter. The electrical storage device becomes charged through a charging device from the external power source.

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

A hydraulic drive device for a hydraulic excavator, includes: a first hydraulic pump; a first boom directional control valve and a second arm directional control valve which are connected in parallel to the first pump; a second hydraulic pump; and a second boom directional control valve and a first arm directional control valve which are connected in parallel to the second pump; wherein: the hydraulic drive device also includes: a third hydraulic pump; a third boom directional control valve connected to the third pump and controlling the flow of pressure oil supplied to a boom cylinder; and a third arm directional control valve connected in tandem with the third boom directional control valve and controlling the flow of pressure oil supplied to an arm cylinder.

Hydraulic drive device for working machine

A hydraulic drive system designed so that while maintaining intact a structure of a relief valve having a shockless function, the drive unit hydraulic drive system facilitates changing a driving pressure or braking pressure of a hydraulic swing motor and hence, changing a maximum driving torque or braking torque of the hydraulic swing motor. Inside a swing motor unit is arranged a first swinging relief valve provided with a shockless function to limit a driving pressure or braking pressure of the hydraulic swing motor in order to prevent the pressure from exceeding a first setting pressure. Also, a second swinging relief valve is provided for limiting the driving pressure or braking pressure of the hydraulic swing motor in order to prevent the pressure from exceeding a second setting pressure that is lower than the first setting pressure.

Hydraulic drive system for hydraulic working machine

Disclosed is a hybrid-type construction machine equipped with a swing hydraulic motorand a swing electric motorin combination to save energy, the construction machine ensuring high operability of a swing bodyand providing high energy efficiency. In accordance with the amount of manipulation of a swing control lever, the construction machine changes a rate of a torque of the swing electric motorwith respect to that of the swing hydraulic motor. The construction machine also controls a relief pressure and the torque of the swing electric motorin accordance with the amount of manipulation of a swing control lever, a pressure of the swing hydraulic motor, and a rotating speed of the swing electric motor

Construction machine having swing body

A hybrid construction machine drives the upper swing structure using a hydraulic motor and an electric motor together and is capable of regenerating the energy of the upper swing structure in deceleration or stopping into electric power and using the regenerated electric power for assisting the hydraulic motor for driving the upper swing structure. The opening area characteristics of a meter-out restrictor and a bleed-off restrictor of a swing directional control valve are set to become larger than for construction machines driving the upper swing structure with the hydraulic motor alone. Torque of the electric motor is controlled so that the total sum of the actual torque occurring in the hydraulic and electric motors in deceleration or acceleration of the hydraulic motor equals the torque occurring when the opening area of the meter-out restrictor or the bleed-off restrictor is set at the prescribed opening area.

Hybrid construction machine

A hybrid construction machine is provided with a variable displacement hydraulic pumpwhich supplies hydraulic oil to a hydraulic actuator, an enginewhich is provided to be able to drive and rotate the hydraulic pump, an electric motorwhich is provided to be able to drive and rotate the hydraulic pump, an engine control dial, a controllerand an operating lever. The controller changes the rotation speed of the engineto reduce fuel consumption according to power generated by the engine, and changes displacement of the hydraulic pumpbased on the rotation speed of the engine, the dial position of the engine control dialand the amount of operation on the operating lever

A hydraulic circuit for a hydraulic working machine is composed of a main pump, a boom cylinderarranged for extension or contraction by pressure oil from the main pump, a directional control valvefor controlling flows of pressure oil to be fed from the main pumpto a bottom chamberand rod chamberof the boom cylinder, a control unitfor performing a change-over control of the directional control valve, a pilot pump, a jack-up selector valvefor controlling a flow of pressure oil delivered from the pilot pump, a flow control valveconnected on an upstream side of the directional control valveto a meter-in port of the directional control valvesuch that the flow control valvecan be changed over by the jack-up selector valve, and a center bypass selector valveconnected on a downstream side of the directional control valveto a center bypass port of the directional control valvesuch that the center bypass selector valvecan be changed over by the jack-up selector valve. The hydraulic circuit performs a change-over of the jack-up selector valvein accordance with a bottom pressure on the boom cylinder

A hydraulic drive system is mounted on a hydraulic excavator, and is provided with a directional control valvefor a boom, a directional control valvefor an arm, a boom control devicefor selectively controlling the directional control valvefor the boom, and an arm control devicefor selectively controlling the directional control valvefor the arm. The directional control valvescontrol a boom cylinderand an arm cylinder, respectively, which are driven by pressure oil delivered from a main hydraulic pump. The hydraulic drive system is provided with a communication control unit for communicating a rod chamberof the boom cylinderand a bottom chamberof the arm cylinderwith each other when a stroke of the arm control devicehas become a predetermined amount S or greater.

Hydraulic drive apparatus

To permit using hold-side pressure oil in a first hydraulic cylinder for the acceleration of a second hydraulic cylinder upon performing a combined operation of the first and second hydraulic cylinders, a hydraulic drive system is provided with a main hydraulic pump, a boom cylinderand an arm cylinder, a directional control valvefor a boom and a directional control valvefor an arm, and a boom control deviceand an arm control device. The hydraulic drive system is also provided with a pressure oil feed means for feeding pressure oil in a rod chamberof the boom cylinderto an upstream side of the directional control valvefor the arm when a bottom pressure of the arm cylinderhas increased to a high pressure equal to or higher than a predetermined pressure. This pressure oil feed means includes a flow combiner valvearranged in a reservoir linewhich can communicate to the rod chamberof the boom cylinder. When the bottom pressure of the arm cylinderis the predetermined pressure or higher, the flow combiner valvemaintains a communication line, which communicates the reservoir lineand the upstream side of the directional control valvefor the arm with each other, in a state that pressure oil can be fed to the upstream side of the directional control valvefor the arm.

Hydraulic drive device

A hydraulic drive unit is provided with a boom cylinder, an arm cylinder, a communication line communicating a rod chamber of the boom cylinder and a bottom chamber of the arm cylinder with each other, and a switching valve arranged on the communication line for communicating or shutting off the communication line in accordance with a rod pressure of the boom cylinder. When an arm-crowding single operation is performed and by its digging counterforce, a rod pressure of the boom cylinder rises to a high pressure of at least a predetermined pressure, the switching valve is changed over from a shut-off position to a communicating position to feed pressure oil from the rod chamber to the bottom chamber. The boom cylinder is hence caused to automatically extend, thereby avoiding lifting of a hydraulic excavator body.

Hydraulic drive unit

A hydraulic driving unit is provided with a directional control valveand directional control valvefor controlling a boom cylinderand arm cylinder, both of which are driven by pressure oil delivered from a main hydraulic pump, respectively, a boom control devicefor selectively controlling the directional control valveand an arm control devicefor selectively controlling the directional control valve, and is mounted on a hydraulic excavator. To permit effective use of pressure oil in a rod chamberof the boom cylinderwhen a bottom pressure of the arm cylinderhas become high while performing a combined operation such that pressure oil is being supplied to bottom chambersof the boom cylinderand arm cylinder, the hydraulic driving unit is provided with a communication controlling means for bringing the rod chamberof the boom cylinderand the bottom chamberof the arm cylinderinto communication with each other when the bottom pressure of the arm cylinderhas increased to a high pressure equal to or higher than a predetermined pressure.

Hydraulic driving unit

When an arm end exceeds a boundary line K,and enters a slowdown area R,a proportional solenoid pressure reducing valve,is operated to reduce a pilot pressure for slowing down a first boom cylinder,A, thereby slowing down an arm end speed. When the arm end exceeds a boundary line K,and enters a restoration area R,a restoration gain is calculated in control gain block,depending on an intrusion amount by which the arm end enters the restoration area, while a feedback gain is calculated depending on an arm end speed at that time on the basis of functions,and,In accordance with these gains, a second boom,is automatically dumped depending on the intrusion amount of the arm end into the restoration area and the arm end speed at that time so that the arm end is moved for return to the slowdown area. As a result, such work as requiring a work front to be moved toward the operator is continuously smoothly performed and working efficiency is improved.

Interference prevention system for two-piece boom type hydraulic excavator

Growing community of inventors

Ushiku, Japan

Yusuke Kajita