Abstract: 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 (28); a forced charging switch (41); a work machine monitor (43) that notifies an operator that a charging rate of a battery (33) falls to be lower than a critical charging rate; and a machine controller (46). The machine controller (46) actuates a generator motor (31) as a generator to forcedly charge the battery (33) when a gate lock lever (26) is operated to a lock position (D), an engine control dial (12) designates a low idle engine speed, and the forced charging switch (41) is operated.

Abstract: An engine cover (23) is provided between a counterweight (7) and a rear surface part (15B) of a cab (15) to be capable of opening/closing in an upper-lower direction and a heat exchanger cover (28) is provided between the rear side of a left side surface part (15C) and a right side surface part (15D) of the cab (15) and a revolving frame (6). The heat exchanger cover (28) is formed of a horizontal-opening structure of being rotatable in a front-rear direction to the revolving frame (6) with a front end (28C) in the front-rear direction as a fulcrum and a rear end (28D) in the front-rear direction as a free end. A heat exchanger cover lock mechanism (32) is provided on the rear end side of the heat exchanger cover (28) to hold the heat exchanger cover (28) in a closed state, and in a state where both the heat exchanger cover (28) and the engine cover (23) are closed, the engine cover (23) covers the rear end (28D) of the heat exchanger cover (28) and the heat exchanger cover lock mechanism (32) from backward.

Abstract: In a hydraulic drive system for an electrically driven hydraulic work machine that executes flow rate control of a hydraulic pump by controlling a rotation speed of an electric motor to drive a hydraulic pump to supply a hydraulic fluid to a plurality of actuators, and power consumed by the electric motor reliably limited within a range of preset maximum allowable power without unnecessary degradation of responsiveness of the electric motor. To this end, a controller includes a maximum angular acceleration limitation section (allowable rate computation section and rate limitation section), computes hydraulic power consumed by a main pump, computes a maximum angular acceleration allowed for an electric motor on the basis of a magnitude of the hydraulic power and a preset maximum allowable power consumable by the electric motor, and limits an angular acceleration of the electric motor not to exceed the maximum angular acceleration.

Abstract: A hydraulic drive system for an electrically-driven hydraulic work machine makes it possible to make a rated voltage of various electric equipment such as power storage devices common to one of an electrically-driven hydraulic work machine that is capable of being operated with lower horsepower and to prevent that only a power storage situation of one of the plurality of power storage devices significantly degrades together with operation of the electrically-driven hydraulic work machine and besides, to extend a time period within which each of actuators of the electrically-driven hydraulic work machine can obtain a predetermined speed. Accordingly, a controller 50 includes a virtual limitation torque calculation section 51 and electric motor rotational speed control sections 52 and 53.

Abstract: 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.

Abstract: Pressure compensating valves not fully closing at the stroke end are employed, and upon the operator's operation for the traveling, pilot primary pressure is reduced and supplied to remote control valves 34c-34h of non-travel operating devices. Thus, the inflow of the hydraulic fluid into non-travel actuators is suppressed and a necessary amount of hydraulic fluid for travel motors is secured in travel combined operation. Accordingly, when saturation occurs in a construction machine's hydraulic drive system performing the load sensing control due to combined operation with a great load pressure difference between two actuators, deceleration/stoppage of an actuator on the low load pressure side is prevented by preventing full closure of the pressure compensating valve on the low load pressure side, while also preventing deceleration/stoppage of a high load pressure actuator by securing a necessary amount of hydraulic fluid for the high load pressure actuator.

Abstract: A hydraulic excavator (1) includes a wireless authentication device (52) performing wireless authentication with a portable key device (51) and a vehicle body controller (48) for starting an engine (15) based on authentication by the wireless authentication device (52) and an operation of a start switch (12). The wireless authentication device (52) transmits a request signal within an authenticable range and performs authentication when it receives an ID code for authentication replied from the portable key device (51) based on the transmitted request signal. The vehicle body controller (48) prohibits driving of a hydraulic actuator (5E, 5F, 5G, 5H, 2E, 2F, 3A) when the portable key device (51) is outside of the authenticable range even if a gate lock lever (13) has been switched to an unlock position.

Abstract: A cap holder (21) that is attached to the inner surface side of a fuel filling door (19) in a state of facing an inner surface of the fuel filling door (19) with an interval in order to hold a cap (11K) removed from a fuel tank (11) and a lock (22) that locks the fuel filling door (19) from the outside in a state where the fuel filling door (19) closes a fuel filling opening (18) are provided on the fuel filling door (19). The lock (22) has a lock lever (22C) that rotationally moves between a locking position where the fuel filing door (19) maintains a state of closing the fuel filling opening (18) and an unlocking position where the fuel filling door (19) allows opening of the fuel filling opening (18). This lock lever (22C) is configured by a long member a base end of which is rotatably attached to the fuel filling door (19) and a leading end of which is allowed to enter a gap between the fuel filling door (19) and the cap holder (21).

Abstract: A bucket cylinder includes a cylindrical tube, a rod having a cylindrical boss part mounted to a protruding end side of the rod, and a protective cover having one side supported by a cover guide provided on the tube, while the other side is mounted on the boss part. A protective protrusion protruding outward in a radial direction of the boss part and protecting the boss part and the protective cover is provided on the boss part. The protective cover is formed having a plate shape by a material having elasticity, and the protective cover includes a plate part for protecting the rod between the cover guide and the boss part and a winding part formed so as to be wound around an outer periphery of the boss part from a distal end side of the plate part. A protective protrusion engaging hole into which the protective protrusion is engaged is provided in the winding part at a position corresponding to the protective protrusion.

Abstract: An upper revolving structure (4) includes a revolving frame (6), an engine (7), a fuel tank (11), an operator's seat platform (16) provided by covering an upper side of the fuel tank (11), an operator's seat (18) mounted on the operator's seat platform (16), and a cab (22) covering a periphery of the operator's seat (18). The fuel tank (11) is disposed between the revolving frame (6) and the operator's seat platform (16), brought closer to a left surface part (25) side of the cab (22). A level gauge (29) is provided on an outer surface of the fuel tank (11). A fuel filling opening (27) surrounding a fuel filling port (11J) of the fuel tank (11) and a level gauge opening (28) are provided on the left surface part (25) of the cab (22).

Abstract: Provided is a grip heater apparatus for a construction machine that can improve operability by heating the grip portions of left and right operating levers and maintaining a favorable operating environment for the left and right operating levers when work is carried out in a cold region and the operator's hands get cold. The grip heater apparatus includes: left and right grip heaters 31 and 32 provided in grip portions of left and right operation levers 26 and 28, respectively; a battery supplying electric power to the left and right grip heaters; a heater switch 34 for instructing the left and right grip heaters to be turned on or off; and a control device supplying the electric power from the battery to the left and right grip heaters only when the engine is running, the gate lock lever 27 is at a getting-on/off prevention position, and the heater switch instructs the left and right grip heaters to be turned on.

Abstract: 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.

Abstract: A hydraulic drive system for a track device of crawler type has right and left hydraulic track motors. The hydraulic drive system is capable of correcting for skew occurring in the straight line traveling of the track device. A traveling test is conducted upon shipment from a factory. If skew is noted during the test, a plug disposed on the side of a valve opening-side pressure receiving portion of a pressure compensating valve for the track which is lower in speed is removed and, replaced with an adjusting mechanism-mounted plug having an adjusting pin. The pin is operated so as to strengthen a biasing force of a target compensating differential pressure adjusting spring. An opening in the pressure compensating valve is thereby corrected in an opening direction and a flow rate to one of the left and right track motors is thereby adjusted to be equal to the other motor.

Abstract: An electrically-operated hydraulic work machine drives an actuator with a hydraulic pump driven by an electric motor and exercises load sensing control by controlling the rotation speed of the electric motor. The useful life of an electrical storage device, which is an electrical power source for the electric motor, is increased by suppressing the horsepower consumption of the hydraulic pump. This prolongs the operating time of the electrically-operated hydraulic work machine, and reduces the size of the electric motor. A controller exercises load sensing control over a variable displacement main pump by controlling the rotation speed of the electric motor, and provides the main pump with a torque control device that reduces the delivery rate of the main pump when the delivery pressure of the main pump increases, or provides the controller with a control algorithm that performs the same function as the torque control device.

Abstract: A floor-plate side opening part (17B) through which each lever part (24, 26) of a traveling lever pedal (21) is inserted is provided on a front side of a floor plate (18). A mat-side opening part (19C) corresponding to the floor-plate side opening part (17B) is provided on a floor mat (19). A cover member (32) formed of a flat plate part (33) covering the mat-side opening part (19C) and having a slit (33A, 33B) allowing tilting of each lever part (24, 26) and a cylindrical part (34) extending from the flat plate part (33) is provided on the mat-side opening part (19C). An entire-circumferential lip part (19D) is provided on the mat-side opening part 19C. An entire-circumferential stepped part (35) for sealing a space from the entire-circumferential lip part (19D) is provided on the flat plate part (33).

Abstract: To make it possible to efficiently utilize rated output torque of a prime mover by performing total torque control with high precision through precise detection of absorption torque of another hydraulic pump by use of a purely hydraulic structure and feedback of the absorption torque to the side of one hydraulic pump, delivery pressure of a main pump and a load sensing drive pressure are supplied to a torque feedback circuit, which modifies the delivery pressure of the main pump to achieve a characteristic simulating the absorption torque of the main pump, and outputs the modified pressure. An output pressure of the torque feedback circuit is supplied to a torque feedback piston, which controls displacement of the main pump so as to decrease the displacement of the main pump and thereby decrease maximum torque as the output pressure increases.

Abstract: To cope with a variety of flow rate balance required of two actuators flexibly in combined operations driving two actuators of high maximum demanded flow rates at the same time while suppressing the wasteful energy consumption caused by the throttle pressure loss in a pressure compensating valve, the arrangement is such that when the demanded flow rate of a boom cylinder 3a is lower than a prescribed flow rate, the boom cylinder 3a is driven only by hydraulic fluid delivered from a single flow type main pump 202 and when the demanded flow rate of the boom cylinder 3a is higher than the prescribed flow rate, the hydraulic fluid delivered from the single flow type main pump 202 and hydraulic fluid delivered from a first delivery port 102a of a split flow type main pump 102 are merged together and the boom cylinder 3a is driven by the merged fluids.

Abstract: A heat exchanging device includes a frame member assembled having a square frame shape by using a lower frame extending in a front and rear direction and mounted on a revolving frame, side frames extending to an upper side from both ends of the lower frame, and an upper frame extending on an upper part of the side frames. A cooling fan is disposed in a state in which each of the blades enters into the frame member from an engine side end surface with respect to the frame member. An oil cooler and a radiator are mounted on a mounting surface plate on an opposite side to the engine and interposing said cooling fan at an interval from the cooling fan with respect to the frame member. A flat plate shaped shroud surrounding each of the blades of the cooling fan and forming a fan accommodating chamber among the frame member, the oil cooler, and the radiator is mounted on the engine side end surface of the frame member.

Abstract: In a hydraulic driving system for construction machines, when track motors 3f and 3g are operated and the delivery pressure of a main pump 2 increases to a second value PS2 of the set pressure of a main relief valve 14, the set pressure of a signal pressure relief valve 16 increases from a third value PA1 to a fourth value PA2, which is smaller than the second value PS2 of the set pressure of the main relief valve 14, the difference between the second value PS2 and the fourth value PA2 being smaller than the target LS differential pressure. With such a structure, even if one of actuators reaches the stroke end and the delivery pressure of the hydraulic pump rises to the set pressure of the main relief valve, the other actuators do not stop, and further when the main relief valve is configured to increase the set pressure during operation of a specific actuator, the load pressure of the specific actuator does not increase to the increased set pressure of the main relief valve.

Abstract: The object is to make it possible to efficiently utilize rated output torque of the prime mover by performing total torque control with high precision through precise detection of absorption torque of the other hydraulic pump by use of a purely hydraulic structure and feedback of the absorption torque to the one hydraulic pump's side. For this purpose, the hydraulic drive system is equipped with: a torque feedback circuit 112v which is supplied with delivery pressure of a main pump 202 and load sensing drive pressure, modifies the delivery pressure of the main pump 202 to achieve a characteristic simulating the absorption torque of the main pump 202, and outputs the modified pressure; and a torque feedback piston 112f which is supplied with output pressure of the torque feedback circuit and controls displacement of a main pump 102 so as to decrease the displacement of the main pump 102 and thereby decrease maximum torque T12max as the output pressure increases.