Abstract: 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.

Abstract: Disclosed is a working machine capable of preventing damage to a filter due to excessive accumulation of particulate matter (PM), even under a situation that requires, prior to compulsory regeneration of the filter, moving the machine to a place in which to perform the regeneration work. The working machine that includes an exhaust treatment device 4 having a filter 6 to trap the PM, a regeneration control section 31 for compulsorily regenerating the filter, and a regeneration instruction device 23 for instructing the regeneration control section 31 to start the compulsory regeneration. Further, when a deposition quantity estimating element determines that an actual PM deposition quantity has reached a deposition alarm level, an alarm device 12 notifies an operator that the time has come to start the movement of the working machine to the place of regeneration.

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: A reduction gear is mounted on a revolving frame, and an electric motor having an electric motor shaft is disposed on the reduction gear. A hydraulic motor having a shaft is disposed on an upper side of the electric motor. A shaft insertion hole through which an upper end side of the electric motor shaft is inserted is provided in a lid portion of an electric motor casing. A male spline portion provided on the hydraulic motor shaft is spline-coupled to a female spline portion provided on the electric motor shaft. A bearing is provided between the shaft insertion hole and the electric motor shaft, and a pressure tight seal is provided by being located upwardly of the bearing. Hence, spline coupling portions of the female spline portion and the male spline portion are constantly lubricated by making use of drain oil which has leaked from the hydraulic motor.

Abstract: A hybrid construction machine is capable of performing satisfactory operations even when trouble occurs that disables the electric motor from outputting torque. The hybrid construction has both a hydraulic motor and an electric motor driving the swing structure and a controller for switching between a hydraulic/electric hybrid swing mode (using both the hydraulic motor and the electric motor) and a hydraulic-alone swing mode (using only the hydraulic motor). The switching is executed while achieving satisfactory operability and performance in each mode. Normally, an energy saving operation is performed in the hydraulic/electric hybrid swing mode. When the electric amount of an electricity storage device has gone out of a prescribed range or an abnormality has occurred in an electric system (e.g., failure of an inverter), the swing mode is switched to the hydraulic-alone swing mode so that driving with normal braking torque is possible by the hydraulic motor alone.

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 circuit for a hydraulic working machine is composed of a main pump 21, a boom cylinder 11 arranged for extension or contraction by pressure oil from the main pump 21, a directional control valve 22 for controlling flows of pressure oil to be fed from the main pump 21 to a bottom chamber 11a and rod chamber 12b of the boom cylinder 11, a control unit 23 for performing a change-over control of the directional control valve 22, a pilot pump 24, a jack-up selector valve 25 for controlling a flow of pressure oil delivered from the pilot pump 24, a flow control valve 26 connected on an upstream side of the directional control valve 22 to a meter-in port of the directional control valve 22 such that the flow control valve 26 can be changed over by the jack-up selector valve 25, and a center bypass selector valve 27 connected on a downstream side of the directional control valve 22 to a center bypass port of the directional control valve 22 such that the center bypass selector valve 27 can be changed over

Abstract: In an attachment control apparatus for a hydraulic excavator having a hydraulic circuit that includes a hydraulic pump, a plurality of actuators having a breaker which is an attachment actuator, and a plurality of flow control valves having an attachment flow control valve that is switched by operation pilot pressure from a control pedal device to supply delivery fluid of the hydraulic pump to the attachment actuator, if the control pedal device is operated in a state where an attachment mode is not selected by an attachment selection device, the movement of the attachment actuator is limited. Thus, failure and reduced life of the attachment and other hydraulic devices can be prevented in the event that an operator has forgotten to switch from a normal mode to an attachment mode and has operated the attachment.

Abstract: The present invention provides an information management system suitable for a construction machine, which drives a solenoid valve separately from normal control to thereby make it possible to perform failure diagnosis for the solenoid valve and each sensor easily and with satisfactory accuracy. A controller has a failure diagnosis mode selected by a control panel of a display device. When the failure diagnosis mode is selected by the control panel and instructions for failure diagnosis related to a specific solenoid valve of a plurality of solenoid valves are given, the controller outputs a failure diagnosis drive signal to the specific solenoid valve, inputs an output value from a sensor related to the specific solenoid valve among a plurality of sensors, and displays, based on the output value from the specific sensor, information as to whether the specific solenoid valve and the specific sensor are normal on a display device.

Abstract: During a swing start, a pump torque calculating section associated with pump delivery pressure, a pump torque calculating section associated with swing operation pressure, and a maximum value selecting section of a controller perform control to change a maximum absorption torque of a second hydraulic pump between Tb and Tc in accordance with a delivery pressure of the second hydraulic pump. In an operation combining swing with other motion, a subtraction section performs a calculation to subtract a maximum absorption torque Tp2 of the second hydraulic pump from a total pump torque Tr0 to thereby distribute an amount of torque reduced in the second hydraulic pump to a first hydraulic pump associated with an actuator other than a swing motor. Further, a required flow rate can be supplied to the swing motor, thus achieving a smooth shift to a constant speed swing.

Abstract: When an output value of an exhaust resistance sensor 34 has reached or exceeded a set value ?Pa, a controller 20 executes recovery control of a filter of an exhaust gas purification device 32 after conducting exhaust temperature increasing control by operating a pump discharge pressure increasing device (solenoid proportional valve) 38 so that exhaust gas temperature as an output value of an exhaust temperature sensor 33 reaches a preset value Ta. Thus, the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature irrespective of the operating environment and the fuel consumption can be kept at a minimum necessary level.

Abstract: A hydraulic driving device for a working machine surely prevents behavior of a single rod double acting cylinder not intended by an operator when discharge pressure of a main pump is raised to raise exhaust gas temperature to temperature required for burning particulate matter. A selector valve 160 interposed between a spool valve 61 and a rod chamber of a single rod double acting cylinder 51 and a section (a filter regeneration time actuation valve 122, a vehicle body controller 150) controlling the selector valve, are provided. A switch control section prevents a flow of oil directed from the rod chamber of the cylinder toward the spool valve by actuating the selector valve by a poppet of the selector valve when a by-pass cut valve 110 is controlled to increase a load of an engine 21 to a degree exhaust gas temperature reaches temperature required for burning particulate matter.

Abstract: 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.

Abstract: Provided is a hybrid construction machine (driving the upper swing structure using a hydraulic motor and an electric motor together) 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 driving of the upper swing structure, while also being capable of securing satisfactory operational feeling and operation capability even when the electric motor does not operate. When the electric motor is not driven, a controller controls a hydraulic circuit system (specifically, a swing direction/flow rate control valve, a center bypass cut valve and a regulator) so as to increase output torque of the hydraulic motor by an amount corresponding to torque to be compensated for the non-driving of the electric motor compared to cases where the electric motor is driven.

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: A hydraulic drive system for a hydraulic working machine sets a delivery pressure at a preset value upon raising a temperature of exhaust gas to a temperature needed for combustion of particulate matter by increasing a load to be applied to an engine. In a non-operation state, a variable restrictor is controlled by a controller and a delivery pressure control valve to increase a delivery pressure of a variable displacement hydraulic pump, so that the load is increased to raise the temperature of exhaust gas to the temperature needed for the particulate matter combustion. At this time, the controller controls the delivery pressure control valve such that a delivery pressure to be detected by a delivery pressure sensor will conform with a preset reference delivery pressure. The reference delivery pressure is set to a minimum pressure that can provide the exhaust gas with combustion heat.

Abstract: A hydraulic drive system realizes a jack-up operation without arrangement of a flow rate control valve and center bypass selector valve. The hydraulic drive system has first and second hydraulic pumps, first and second directional control valves for controlling boom cylinders, a third directional control valve for controlling the boom cylinders, and a third hydraulic pump for feeding pressure oil to the third directional control valve. A jack-up selector valve has a second select position where, when a pressure in bottom chambers of the boom cylinders is not higher than a predetermined pressure, feeding of pressure oil, which is delivered from the first hydraulic pump and second hydraulic pump, to rod chambers of the boom cylinders, is held permissible in association with switching of the second directional control valve and third directional control valve by a manipulation of a control device.

Abstract: A current load rate of an engine 10 is computed and a maximum absorption torque of at least one hydraulic pump 1, 2 is controlled so that the load rate is held at a target value. Engine stalling can be prevented by decreasing the maximum absorption torque of the hydraulic pump under a high-load condition. When an engine output lowers due to environmental changes, the use of poor fuel or other reasons, the maximum absorption torque of the hydraulic pump can be decreased without a lowering of the engine revolution speed. Further, the present invention is adaptable for any kinds of factors causing a lowering of the engine output, such as those factors that cannot be predicted in advance or are difficult to detect by sensors. In addition, because of no necessity of sensors, such as environment sensors, the manufacturing cost can be reduced.

Abstract: Disclosed is a hydraulic drive system for a working machine, which enables to conduct forced regeneration continuously for a sufficient time. Based on an input of a lock detection signal S1 from a gate lock detection switch 40, a controller 50 detects that a gate lock lever 32 for controlling a gate lock on/off valve 33 is in a locked state, in other words, hydraulic actuators such as an arm cylinder 12 arranged on a hydraulic excavator 1 are all in non-operated states. Upon an input of a forced regeneration command signal So from a forced regeneration switch 53 in this detected state, control signals Cp,Cf are outputted to a boosting control valve 51 and regulator 52 to make a forced regeneration means (an arm cylinder control valve 27 and the regulator 52) conduct forced regeneration.

Abstract: A hydraulic drive system for a working machine provides improved safety during forced regeneration. Upon input of a forced regeneration command signal from a forced regeneration switch, a controller detects non-operated states of all hydraulic actuators such as an arm cylinder arranged on a hydraulic excavator based on a lock detection signal from a gate lock detection switch, and also an attitude of a front working mechanism. The attitude is proper from the standpoint of safety. The detection is based on an arm angle signal from an arm angle sensor, a bucket angle signal from a bucket angle sensor and a boom pressure signal from a boom pressure sensor. Taking the detection of the non-operated states and proper attitude as conditions, the controller outputs control signals to a boosting proportional solenoid valve and flow-rate controlling, proportional solenoid valve to make a forced regenerator conduct forced regeneration.