Hitachi Construction Machinery Co., Ltd.

Hitachi Construction Machinery Tierra Co., Ltd.

Hajime Yoshida

Shuuhei Noguchi

Yoshifumi Takebayashi

Natsuki Nakamura

Hajime Ishii

Daisuke Oka

Kazushige Mori

Yasutaka Tsuruga

Kiwamu Takahashi

Shogo Kimura

Makoto Motozu

Hajime Kurikuma

Shigeru Hirasawa

Taihei Maehara

Teruo Irino

Tetsuya Nakabayashi

Motoaki Ishii

Syuuhei Noguchi

Provided is a construction machine that can prevent a machine body from being lowered since a blade is not put into a float state even where a misoperation is made by an operator when the machine body is in a jacked-up state, and that can perform a favorable leveling operation by putting the blade into the float state in accordance with an operator's operation when the machine body is not in the jacked-up state. A hydraulic excavator includes a controllerthat determines whether or not the machine body is in a jacked-up state and controls a float valve. In the case where it is determined that the machine body is not in the jacked-up state, the controllerchanges over the float valveto a float position V and invalidates an operation of a blade control valve, in accordance with a float instruction. In the case where it is determined that the machine body is in the jacked-up state, the controllerholds the float valvein a reference position IV and validates the operation of the blade control valve, irrespectively of the presence or absence of the float instruction.

Construction machine

A hydraulic drive system for a hydraulic excavator that enables leveling work and a jack-up operation by a blade in a float state, that can prevent a body from falling even when an operator has falsely operated the hydraulic excavator during the jack-up operation by the blade, and that yet can perform favorable leveling work with the blade turned into the float state is provided. A float switch, a float valve, and a controllerare provided, the float valveis changed over to a float position VI upon operating the float switchwhen the blade is not in a jack-up state, the float valveis changed over from the float position VI to a normal position V when the float valveis in a state of being at the float position VI and an operation lever devicehas been operated, and the float valveis kept at the normal position V when the float valveis at the normal position V and the float switchhas been operated in the jack-up state.

Hydraulic drive system for construction machine

A filter () traps particulate matter in an exhaust gas. A filter inlet side pressure sensor () is provided in an inlet side of the filter (). An EGR valve inlet side pressure sensor () is provided in an inlet side of an EGR valve (). A regeneration controller (C) determines whether or not the filter inlet side pressure sensor () is in failure based upon a difference between a pressure value detected by the filter inlet side pressure sensor () and a pressure value detected by the EGR valve inlet side pressure sensor (). When the filter inlet side pressure sensor () is in failure, the regeneration controller (C) performs control of regeneration treatment using a differential pressure calculated based upon a pressure value detected by the EGR valve inlet side pressure sensor () and a pressure value detected by the filter outlet side pressure sensor ().

To provide a small hydraulic excavator, which even may have an upperstructure formed such that at least its rear end swings within a body width range and having a limited installation space for devices, that allows an accumulator to be disposed and allows the accumulator to be protected from external force generated during work. The present invention relates to a rear small-swing type mini excavator that includes an accumulatoraccommodating and recovering potential energy and hydraulic energy used by at least one of drives of an undercarriage, an upperstructureformed such that its rear end swings within the body width range of the undercarriage, and a working device. In the rear small-swing type mini excavator, the accumulatoris disposed between a valve blockand a front longitudinal boardof a longitudinal board member included in a main framealong the front longitudinal board, and a pipe connected to the accumulatorand the valve blockis disposed closer to the accumulatorand the valve block

Small hydraulic excavator

Provided is a construction machine that can prevent a machine body from being lowered without placing a blade in a floating state when the machine body is jacked up, even if the operator performs an erroneous operation, and that can perform favorable leveling work by placing the blade in the floating state when the machine body is not jacked up. A hydraulic excavator includes a pressure sensor that detects the pressure in a bottom-side oil chamber of a blade cylinder, and a controller that switches between validation and invalidation of a floating command and a lowering command for a blade operation device. In the case where the pressure detected by the pressure sensor is less than a predetermined value, the controller switches a solenoid selector valve to an interruption position to invalidate the floating command when a forward stroke of the operation lever is equal to or more than a reference value. In the case where the pressure detected by the pressure sensor is equal to or more than the predetermined value, the controller holds the solenoid selector valve in a communication position to validate the floating command when the forward stroke of the operation lever is equal to or more than the reference value.

To achieve saving of fuel consumption and noise reduction by adopting a hybrid type and miniaturizing an engine and to ensure safe and reliable battery charging in a case in which a charge amount of a battery is quite insufficient, a hydraulic work machine includes: a gate lock sensor (); a forced charging switch (); a work machine monitor () that notifies an operator that a charging rate of a battery () falls to be lower than a critical charging rate; and a machine controller (). The machine controller () actuates a generator motor () as a generator to forcedly charge the battery () when a gate lock lever () is operated to a lock position (D), an engine control dial () designates a low idle engine speed, and the forced charging switch () is operated.

Hybrid work machine

A construction machine that can easily regulate a set maximum flow rate at a time of replacement of an attachment and that can improve an energy conservation performance is provided. A controller selects a corresponding map in response to an attachment designation signal from among maps each of which sets a relationship between an operation signal per type of the attachment and a flow rate of a hydraulic fluid supplied to an actuator, generates a control signal by causing the selected map to refer to the operation signal, and controls a flow control valve of an attachment flow rate regulation valve device in such a manner that a position of the flow control valve is switched over from a neutral position on the basis of the control signal. An unloading valve that maintains a differential pressure across the flow control valve is disposed in the attachment flow rate regulation valve device.

Provided is a hybrid work machine in which a hybrid system and a downsized engine are used. The hybrid work machine performs rapid charging of a power storage device while preventing decreases in the output power of a hydraulic pump. A vehicle body controller performs engine revolution speed decreasing control in which, if the charge rate of a battery becomes equal to or less than a minimum charge rate, the target revolution speed of an engine is reduced. The vehicle body controller also performs torque reducing control in which the maximum absorption torque of a hydraulic pump is reduced. By performing these control operations, the vehicle body controller coercively generates surplus torque for the engine and operates a generator-motor as a generator.

During an operation, a control device () for performing output control of an engine () determines whether or not the engine () and/or an exhaust gas purifying device () has a malfunction. If it is determined that the engine () and/or the exhaust gas purifying device () has a malfunction, a highest rotational speed of the engine () is controlled to a second rotational speed (Nt) higher by a predetermined amount (&#x3b1;) than a first rotational speed (Ns) at which an engine maximum torque (Tm) before the malfunction can be outputted. In this case, a maximum fuel injection quantity of the engine () is limited so that a rated torque (Tr) before the malfunction can be outputted at the first rotational speed (Ns).

Engine output control device for a construction machine

A regeneration device () executes regeneration treatment of a filter () in an exhaust gas purifying device () by burning particulate matter trapped in the filter (). The regeneration device () interrupts the regeneration treatment of the filter () when an exhaust gas temperature T detected by an exhaust gas temperature sensor () becomes less than an exhaust gas temperature threshold Tt during a period of performing the regeneration treatment of the filter (). In a case where the regeneration treatment of the filter () is interrupted, when the exhaust gas temperature T becomes equal to or more than the exhaust gas temperature threshold Tt, the regeneration treatment of the filter () is restarted.

A regeneration device that performs regeneration treatment of a particulate matter removing filter estimates a trapping amount of particulate matter trapped in the filter by two systems. Specifically, there are provided an estimating unit that estimates a first estimated trapping amount based upon a rotational speed of an engine and a fuel injection quantity and an estimating unit that estimates a second estimated trapping amount based upon a differential pressure across the particulate matter removing filter. The regeneration device determines whether or not the regeneration treatment is executed based upon whether or not at least one of the two estimated trapping amount is equal to or more than a preset trapping amount threshold value. Further, the regeneration device determines that there is a malfunction in the regeneration device in a case where the second estimated trapping amount is larger than the first estimated trapping amount.

A regeneration device burns particulate matter trapped in a filter in an exhaust gas purifying device to execute regeneration treatment of the filter. The regeneration device performs a determination whether or not the regeneration treatment is executed using a first estimated trapping quantity (H) estimated based upon a differential pressure (&#x394;P=P&#x2212;P) as a difference between pressure (P) in an inlet side and pressure (P) in an outlet side of the filter and a second estimated trapping quantity (H) estimated based upon a rotational speed (N) of an engine, a fuel injection quantity (F) and an exhaust gas temperature (GT). In this case, the determination whether or not the regeneration treatment is executed is performed using only the second estimated trapping quantity (H) when the engine is in a predetermined low rotational condition.

In an engine, an exhaust gas purifying device and a regeneration device, there are provided detectors for detecting working states thereof, such as a rotational sensor, a cooling water temperature sensor, an intake temperature sensor, exhaust gas temperature sensors, pressure sensors, and opening degree sensors. When a trouble occurs in any of the sensors other than the pressure sensors among them, a light degree of operation restrictions is performed for restricting a rotational speed of the engine while it can be determined that particulate matter is not excessively accumulated in a particulate matter removing filter from a detection value of the pressure sensors. On the other hand, when the particulate matter is excessively accumulated in the particulate matter removing filter or when any of the pressure sensors has a trouble, a heavy degree of the operation restrictions accompanied by a fuel injection quantity restriction of the engine is performed.

An engine () electronically controlled by a control device (), a hydraulic motor () for traveling which is driven by a pressurized oil delivered from a hydraulic pump (), and a traveling speed switching member () which switches a traveling speed by the hydraulic motor () at least in two stages of a low speed and a high speed. The control device () includes an output lowering determination unit for determining whether or not a fuel injection amount to be supplied to the engine () is limited and an engine output is in a lowered state and a low-speed control unit in which, when the engine () output is in a lowered state, a traveling speed is controlled to a low speed state kept lower than a high speed even if the traveling speed switching member () has been switched to the high speed side.

A control device for driving/controlling an engine on the basis of a signal from a temperature state detector, a rotation detector, and a rotational speed setting device is provided. The control device includes a start temperature determining processing unit configured to determine whether or not a temperature (T) at start of the engine is less than a predetermined temperature (Tw) and a start control processing is performed in accordance with a set value of a target rotational speed (Nset) by the rotational speed setting device in case the start temperature (T) is equal to or less than the predetermined temperature (Tw). This suppresses occurrence of cavitation by stopping the start of the engine () within a range in which the temperature (T) is equal to or lower than the predetermined temperature (Tw) and the target rotational speed (Nset) of the engine () is higher than a predetermined threshold value (Nca).

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Omihachiman, Japan

Hajime Yoshida