Hitachi Construction Machinery Co., Ltd.

Hitachi Construction Machinery Tierra Co., Ltd.

Shuuhei Noguchi

Hajime Yoshida

Hajime Ishii

Yoshifumi Takebayashi

Makoto Motozu

Hajime Kurikuma

Tetsuya Nakabayashi

Motoaki Ishii

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 ().

Construction machine

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

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.

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).

A control pressure switching valve is disposed between a displacement regulator and a pressure control valve. The control pressure switching valve is switched between a control position (j), in which a load sensing control pressure (PLS) is permitted to be outputted from the pressure control valve to the displacement regulator, and a control release position (k), in which the load sensing control pressure (PLS) to be outputted to the displacement regulator is reduced to a prescribed low pressure value. When the regeneration of a filter is determined to be necessary, the controller switches the control pressure switching valve to the control release position (k). When the load sensing control pressure (PLS) is reduced to the low pressure value with the control pressure switching valve switched to the control release position (k), the displacement regulator increases a delivery displacement of a hydraulic pump, thereby increasing rotational load of an engine.

A regeneration apparatus for executing a regeneration process to an exhaust gas purifying apparatus and an engine control device that controls a rotational speed of an engine according to an instruction value by a rotational speed instruction apparatus are provided. When a directional control valve is in a neutral position, the engine control device controls the rotational speed of the engine to an automatic idle rotational speed (Nai) by an automatic idle selection unit regardless of the instruction value. However, when it is determined that the regeneration process of the exhaust gas purifying apparatus is executed in a state of controlling the rotational speed of the engine at the automatic idle rotational speed (Nai), the engine control device increases the rotational speed of the engine to a regeneration processing rotational speed (N1) higher than the automatic idle rotational speed (Nai).

Growing community of inventors

Higashiomi, Japan

Shuuhei Noguchi