Abstract: A urea water tank (11) is provided with a unit insertion opening (12H) that is disposed on a top surface part (12A) of a tank body (12) and opens more largely than an external dimension (D2) of a sensor unit (20), a sensor mounting member (16) that is disposed on the top surface part (12A) of the tank body (12) and closes the unit insertion opening (12H), and a filter which is formed as a tubular body to surround the sensor unit (20), and inserted in the unit insertion opening (12H) of the tank body (12) from a lower end (24A4)-side, and having an upper end (24A3) mounted on the top surface part (12A) of the tank body (12) by using the sensor mounting member (16).

Abstract: A urea water tank (11) is provided with a unit insertion opening (12H) that is disposed on a top surface part (12A) of a tank body (12) and opens more largely than an external dimension (D2) of a sensor unit (20), a sensor mounting member (16) that is disposed on the top surface part (12A) of the tank body (12) and closes the unit insertion opening (12H), and a filter which is formed as a tubular body to surround the sensor unit (20), and inserted in the unit insertion opening (12H) of the tank body (12) from a lower end (24A4)-side, and having an upper end (24A3) mounted on the top surface part (12A) of the tank body (12) by using the sensor mounting member (16).

Abstract: Provided are a plurality of cameras (96) mounted to an upper swing structure (12) so as to be capable of shooting in different directions, a video storage device (99) for storing videos taken by the plurality of cameras, a controller (40), and a hydraulic excavator (1). The controller has a camera selection section (40a) which when a lower track structure (11), the upper swing structure (12), or a work device (1A) makes an operation, selects a camera in accordance with the operation from among the plurality of cameras (96), and a storage control section (40b) which stores videos taken by the camera selected by the camera selection section (40a) during the operation of the lower track structure, the upper swing structure, or the work device in a video storage device (99).

Abstract: Provided are a plurality of cameras (96) mounted to an upper swing structure (12) so as to be capable of shooting in different directions, a video storage device (99) for storing videos taken by the plurality of cameras, a controller (40), and a hydraulic excavator (1). The controller has a camera selection section (40a) which when a lower track structure (11), the upper swing structure (12), or a work device (1A) makes an operation, selects a camera in accordance with the operation from among the plurality of cameras (96), and a storage control section (40b) which stores videos taken by the camera selected by the camera selection section (40a) during the operation of the lower track structure, the upper swing structure, or the work device in a video storage device (99).

Abstract: To provide an engine lug-down suppressing device for hydraulic work machinery, capable of suppressing deterioration in operability of a hydraulic actuator when the hydraulic actuator is caused to operate quickly from a stopped state. Pilot pressure to a tilting control unit of a variable displacement hydraulic pump is controlled by a solenoid valve. A controller controls the solenoid valve in accordance with a target rotational speed signal from an input unit. This control differs according to whether or not a detector detects the pilot pressure created by an operating lever device. In an entire range of the target engine rotational speed, pump absorption torque at the time when the pilot pressure is not detected, falls within a range equal to or smaller than pump absorption torque at the time when the pilot pressure is detected, and is set to approach the pump absorption torque at the time when the pilot pressure is detected with an increase in the target engine rotational speed.

Abstract: A hydraulic working machine, typically a hydraulic excavator has a travel speed control unit and a boost control unit. The travel speed control unit includes a traveling, hydraulic pressure oil feed unit capable of feeding pressure oil to actuate traveling tilt-angle control devices. The boost control unit includes a boosting, hydraulic pressure oil feed unit capable of feeding pressure oil to actuate an adjustable relief valve. A single hydraulic pressure oil feed unit is commonly usable as the traveling, hydraulic pressure oil feed unit and the boosting, hydraulic pressure oil feed unit, and includes lines communicating with both of the traveling tilt-angle control devices and the adjustable relief valve, a solenoid valve for opening or closing these lines, and a controller for outputting a control signal to control the solenoid valve.

Abstract: A pump torque control system is capable of preventing hunting due to interference between speed sensing control and control of an engine speed of a prime mover when the temperature of a hydraulic fluid is low. A maximum absorption torque is set in a regulator 31 that controls displacement volumes of hydraulic pumps 2 and 3 based on a deviation between target and actual engine speeds of a prime mover 1. A second modification factor calculating section 45 and a control gain modifying section 49, which are included in a controller 23 that performs speed sensing control to ensure that the maximum absorption torque of the hydraulic pumps 2 and 3 is reduced, change a control gain of the speed sensing control based on a value detected by the hydraulic temperature sensor 34 to ensure that the control gain is reduced as the temperature of the hydraulic fluid is reduced.

Abstract: Torque control for a construction machine three-pump system that can accurately control the total absorption torque of first, second, and third hydraulic pumps and effectively use the output torque of an engine. A pump base torque computation section 42 calculates a pump base torque Tr from a target rotation speed. A subtraction section 44 calculates a reference value Tf for the maximum absorption torque available to the first and second hydraulic pumps 2, 3 by subtracting a third pump reference absorption torque T3r from the pump base torque Tr. A correction torque computation section 45 calculates a correction torque value from the delivery pressure of the third hydraulic pump 4. An addition section 46 calculates a target absorption torque Tn by adding the correction torque value Tm to the reference value Tf. A first regulator 31 is controlled so as to obtain the target absorption torque Tn.

Abstract: A hydraulic working machine, typically a hydraulic excavator has a travel speed control unit and a boost control unit. The travel speed control unit includes a traveling, hydraulic pressure oil feed unit capable of feeding pressure oil to actuate traveling tilt-angle control devices. The boost control unit includes a boosting, hydraulic pressure oil feed unit capable of feeding pressure oil to actuate an adjustable relief valve. A single hydraulic pressure oil feed unit is commonly usable as the traveling, hydraulic pressure oil feed unit and the boosting, hydraulic pressure oil feed unit, and includes lines communicating with both of the traveling tilt-angle control devices and the adjustable relief valve, a solenoid valve for opening or closing these lines, and a controller for outputting a control signal to control the solenoid valve.

Abstract: An engine lag down control system for construction machinery has a machinery body controller having first, second and third torque control units and a solenoid valve. The first torque control unit controls a torque control valve to a minimum pump torque corresponding to a target number of engine revolutions when a non-operated state of a control device has continued beyond a monitoring time. The second torque control unit controls the torque control valve such that the above-described minimum pump torque is held for a predetermined holding time subsequent to the operation of the control device from the non-operated state. The third torque control unit controls the torque control valve such that from a time point of a lapse of the predetermined holding time, the pump torque is gradually increased on a basis of a predetermined torque increment rate.

Abstract: On the basis of reference torque and torque correction amount output units (T1 and T2), a torque control command pressure is calculated so that the input torques of first and second pumps are increased. The calculated torque command instruction pressure is then supplied as external command pressure to the varying mechanism of a regulator used for the first and second pumps so as to prevent the input torques of the first and second pumps from being decreased more than necessary. As a result, even when three variable displacement hydraulic pumps are used with the discharge pressure of one of the hydraulic pumps reduced by a pressure reducing valve and further the input torques of the other two hydraulic pumps are decreased by that pressure, the engine output can be efficiently utilized, and the work rate does not decrease.

Abstract: To provide an engine lug-down suppressing device for hydraulic work machinery, capable of suppressing deterioration in operability of a hydraulic actuator when the hydraulic actuator is caused to operate quickly from a stopped state. Pilot pressure to a tilting control unit of a variable displacement hydraulic pump is controlled by a solenoid valve. A controller controls the solenoid valve in accordance with a target rotational speed signal from an input unit. This control differs according to whether or not a detector detects the pilot pressure created by an operating lever device. In an entire range of the target engine rotational speed, pump absorption torque at the time when the pilot pressure is not detected, falls within a range equal to or smaller than pump absorption torque at the time when the pilot pressure is detected, and is set to approach the pump absorption torque at the time when the pilot pressure is detected with an increase in the target engine rotational speed.

Abstract: [Problem] To provide a construction machine, which can surely perform confirmation of conditions around a machine body upon starting work and can start a prime mover even when obstruction exists around the machine body. [Solution] A picture display control means and an engine start delay means are provided. The control means includes a picture switch means 22 for switching a picture of a monitor 13 to a picture of peripheral image information, which is based on video signals from a monitor camera 12, based on an ON signal outputted from an engine key switch device 16.

Abstract: Torque control for a construction machine three-pump system that can accurately control the total absorption torque of first, second, and third hydraulic pumps and effectively use the output torque of an engine. A pump base torque computation section 42 calculates a pump base torque Tr from a target rotation speed. A subtraction section 44 calculates a reference value Tf for the maximum absorption torque available to the first and second hydraulic pumps 2, 3 by subtracting a third pump reference absorption torque T3r from the pump base torque Tr. A correction torque computation section 45 calculates a correction torque value from the delivery pressure of the third hydraulic pump 4. An addition section 46 calculates a target absorption torque Tn by adding the correction torque value Tm to the reference value Tf. A first regulator 31 is controlled so as to obtain the target absorption torque Tn.

Abstract: A pump torque control system is capable of preventing hunting due to interference between speed sensing control and control of an engine speed of a prime mover when the temperature of a hydraulic fluid is low. A maximum absorption torque is set in a regulator 31 that controls displacement volumes of hydraulic pumps 2 and 3 based on a deviation between target and actual engine speeds of a prime mover 1. A second modification factor calculating section 45 and a control gain modifying section 49, which are included in a controller 23 that performs speed sensing control to ensure that the maximum absorption torque of the hydraulic pumps 2 and 3 is reduced, change a control gain of the speed sensing control based on a value detected by the hydraulic temperature sensor 34 to ensure that the control gain is reduced as the temperature of the hydraulic fluid is reduced.

Abstract: When a mode selection command selects an economy mode, a mode selector 700e is turned on and outputs an engine revolution speed modification value ?N0 (?N1=?N0) computed by an engine-revolution-speed modification value computing section 700d. A subtracter 700f subtracts the engine revolution speed modification value ?N1 from a rated target revolution speed Nmax, thereby computing a target engine revolution speed NR2. The computing section 700d computes the engine revolution speed modification value ?N0 depending on a pump delivery pressure mean value Pm. In a table stored in a memory, the relationship between Pm and ?N0 is set such that when Pm is not higher than PA near a midpoint pressure, ?N0 is 0 and when Pm exceeds PA, ?N0 is increased with an increase of Pm. Thus, the revolution speed of a prime mover is reduced by mode selection so as to improve fuel economy.

Abstract: A computing section computes a reference revolution-speed decrease modification amount DNLR; and multiplies an engine revolution speed modification gain KNL by a reference revolution-speed decrease modification amount DNL and then DNLR, to thereby compute an engine revolution-speed decrease modification amount DND based on input change of an operation pilot pressure, which is modified in accordance with DNLR. At the time when a lever operation input from an operation command unit is changed from full stroke to half stroke, if a pump delivery pressure is in a pressure range of a pump absorption torque control region Y where the pump delivery pressure is lower than that in a region X, the reference revolution-speed decrease modification amount computing section 700v computes the modification amount DNLR to be 0, and therefore lowering of a target engine revolution speed with auto-acceleration control is not caused.

Abstract: On the basis of reference torque and torque correction amount output units (T1 and T2), a torque control command pressure is calculated so that the input torques of first and second pumps are increased. The calculated torque command instruction pressure is then supplied as external command pressure to the varying mechanism of a regulator used for the first and second pumps so as to prevent the input torques of the first and second pumps from being decreased more than necessary. As a result, even when three variable displacement hydraulic pumps are used with the discharge pressure of one of the hydraulic pumps reduced by a pressure reducing valve and further the input torques of the other two hydraulic pumps are decreased by that pressure, the engine output can be efficiently utilized, and the work rate does not decrease.

Abstract: A work machine is provided having a starter motor for starting a prime mover, which without provision of any special hydraulic equipment, allows for draining pressure oil that still remains in a hydraulic actuator for driving a front attachment. The work machine is provided with a boom cylinder for driving a front attachment, a flow rate control valve for controlling a flow of pressure oil to be supplied to the boom cylinder, and a pilot valve for producing an output of a pilot control signal, which serves to switch the flow rate control valve, by using, as a primary pressure, pressure oil delivered from a pilot hydraulic pump driven by an engine. A fuel stop switch is provided for performing stop control on a supply of fuel, which drives the engine, and a switch is provided for maintaining drivable a starter motor, which starts the engine, responsive to the stop control of the supply of fuel to the engine by the fuel stop switch.

Abstract: A computing section computes a reference revolution-speed decrease modification amount DNLR; and multiplies an engine revolution speed modification gain KNL by a reference revolution-speed decrease modification amount DNL and then DNLR, to thereby compute an engine revolution-speed decrease modification amount DND based on input change of an operation pilot pressure, which is modified in accordance with DNLR. At the time when a lever operation input from an operation command unit is changed from full stroke to half stroke, if a pump delivery pressure is in a pressure range of a pump absorption torque control region Y where the pump delivery pressure is lower than that in a region X, the reference revolution-speed decrease modification amount computing section 700v computes the modification amount DNLR to be 0, and therefore lowering of a target engine revolution speed with auto-acceleration control is not caused.