Abstract: In a drive unit of a fuel injection device, an electric current is supplied to the fuel injection device by applying a high voltage to the fuel injection device from a high voltage source whose voltage is boosted to a voltage higher than a battery voltage at the time of opening a valve of the fuel injection device. Thereafter, the electric current supplied to the fuel injection device is lowered to a current value at which a valve element cannot be held in a valve open state by stopping the applying of the high voltage from the high voltage source. Thereafter, in a stage where a supply current is switched to a hold current, another high voltage is applied to the fuel injection device from the high voltage source.

Abstract: Provided is a construction machine capable of detecting a stuck-open state of a surplus flow control valve in real time during operation without involving a reduction in the operational speed.

Abstract: Closed circuit lines (33, 43, 53, 63) for connecting hydraulic cylinders (17, 18, 19) and closed circuit pumps (31, 41, 51, 61) are provided with a charge pressure adjustment apparatus (75) via a charge line (72) to variably adjust the pressure in the charge line (72). An operating device (12) for operating the hydraulic cylinders (17, 18, 19) and the charge pressure adjustment apparatus (75) are connected to a control device (81). In the case of extending the hydraulic cylinders (17, 18, 19), the control device (81) increases a set pressure of the charge pressure adjustment apparatus (75) to be high to increase the pressure in the bottom side of the hydraulic cylinders (17, 18, 19) in accordance with an operating amount of the operating device (12).

Abstract: A drive system for a construction machine capable of appropriately controlling a distribution flow rate to each hydraulic actuator and improving operability by an operator is provided.

Abstract: A work machine that can detect abnormality such as a malfunction and wear and tear of each of hydraulic pumps including control equipment with high precision and that can reduce equipment cost is provided. A controller 9 according to the present invention includes a volumetric-transfer-efficiency-calculating section 94 that calculates a volumetric transfer efficiency ?C representing a transfer efficiency of hydraulic oil between a hydraulic cylinder 11 and hydraulic pumps 21 to 23 on the basis of a target discharge flow rate calculated by a target-discharge-flow-rate-calculating section 932 and the speed of the hydraulic cylinder 11 that is detected by a speed sensor 28, and an abnormality decision section 95 that decides whether any one of the hydraulic pumps 21 to 23 is abnormal on the basis of the volumetric transfer efficiency ?C calculated by the volumetric-transfer-efficiency-calculating section 94.

Abstract: A work machine includes a closed circuit system in which there is provided a flushing valve.

Abstract: Delivery ports of a closed circuit hydraulic pump are connected to a head-side chamber and a rod-side chamber of an arm/boom cylinder. A switching valve is arranged between the head-side chamber and a delivery port of an open circuit hydraulic pump. A proportional control valve is arranged between the head-side chamber and a hydraulic fluid tank. At times of cylinder extension, both of the closed and open circuit hydraulic pumps and the switching valve are controlled so that the delivery flows from the closed and open circuit hydraulic pumps are sent to the head-side chamber. At times of cylinder retraction, the closed circuit hydraulic pump and the proportional control valve are controlled so that part of an outward flow from the head-side chamber is returned to the closed circuit hydraulic pump and other part of the outward flow is returned to the hydraulic fluid tank.

Abstract: To provide a hydraulic driving device configured to smoothly extend a hydraulic cylinder. The present invention includes the open circuit E, the closed circuit A, a control device 57, and a control lever 56a. The open circuit E is provided with a flow passage 202 for connecting an outlet port of the open circuit pump 13 and a head chamber 1a of the boom cylinder 1, a selector valve 44a provided in the flow passage 202, a discharge flow passage 404 for connecting a hydraulic fluid tank 25 and a flow passage 200, and a bleed-off valve 64 provided in the discharge flow passage 404. The control device 57 is configured in such a manner that when a manipulate signal for extending the boom cylinder 1 is input from the control lever 56a, the bleed-off valve 64 is closed, the selector valve 44a is subsequently opened, and the open circuit pump 13 is controlled.

Abstract: There is provided a driving device for a work machine, having a closed hydraulic circuit system for driving cylinders with hydraulic pumps, the driving device making the speed of operation substantially the same in both directions of piston rod extension and contraction.

Abstract: To provide a driving device capable of improving the operability of a plurality of single rod hydraulic cylinders. The present invention takes a construction provided with a closed circuit A in which first and third hydraulic pumps 12, 14 and a boom cylinder 1 are connected through selector valves 43a, 45a in a closed-circuit fashion, a plurality of open circuits E, F provided with second and fourth hydraulic pumps 13, 15 and selector valves 44a, 46a that switch the supply destinations of hydraulic oils flowing out from the second and fourth hydraulic pumps 13, 15, and a connection passage 301 connected to sides of the selector valves 44a, 46a from which sides hydraulic oil flows out, and connected to the closed circuit A.

Abstract: A hydraulic closed circuit system using a single rod type hydraulic cylinder prevents the hunting of a flushing valve due to a delay in response of the flushing valve and circuit pressure pulsations, thereby preventing a decrease in operability of the hydraulic cylinder. A single rod type hydraulic cylinder is connected to a hydraulic pump via two hydraulic lines. A flushing valve is connected between the hydraulic lines and a tank; and a control unit is configured to add a predetermined control parameter to a pressure in a lower-pressure hydraulic line of the two hydraulic lines. The magnitude of a pressure in the higher-pressure hydraulic line of the two hydraulic lines is compared with the magnitude of a compensation pressure to which the control parameter has been added, and the flushing valve is switched when the compensation pressure and the higher-pressure hydraulic line pressure are found to be reversed in magnitude.

Abstract: In a drive unit of a fuel injection device, an electric current is supplied to the fuel injection device by applying a high voltage to the fuel injection device from a high voltage source whose voltage is boosted to a voltage higher than a battery voltage at the time of opening a valve of the fuel injection device. Thereafter, the electric current supplied to the fuel injection device is lowered to a current value at which a valve element cannot be held in a valve open state by stopping the applying of the high voltage from the high voltage source. Thereafter, in a stage where a supply current is switched to a hold current, another high voltage is applied to the fuel injection device from the high voltage source.

Abstract: To provide a work machine which, in a configuration provided with a closed-circuit pump and an open-circuit pump, is capable of stabilizing respective pump operations of the closed-circuit pump and the open-circuit pump and of improving the mountability of the closed-circuit pump and the open-circuit pump. The present invention is provided with a closed circuit in which a closed-circuit pump and a boom cylinder are connected annularly, and an open circuit which has an open-circuit pump for making hydraulic fluid flow in from a reservoir and flow out and a connection passage capable of introducing hydraulic fluid into the closed circuit, wherein the closed-circuit pump is installed above the open-circuit pump.

Abstract: In a drive unit of a fuel injection device, an electric current is supplied to the fuel injection device by applying a high voltage to the fuel injection device from a high voltage source whose voltage is boosted to a voltage higher than a battery voltage at the time of opening a valve of the fuel injection device. Thereafter, the electric current supplied to the fuel injection device is lowered to a current value at which a valve element cannot be held in a valve open state by stopping the applying of the high voltage from the high voltage source. Thereafter, in a stage where a supply current is switched to a hold current, another high voltage is applied to the fuel injection device from the high voltage source.

Abstract: To provide a work machine capable of efficiently regenerating the energy owned by hydraulic fluid during a swing deceleration.

Abstract: Provided is a driving device for a working machine, which can drive one or more hydraulic pumps in a large capacity range of as high efficiency as possible. In a driving device for a hydraulic excavator, a controller (41) is provided with a first target delivery-flow-rate setting unit (41a) that computes a first target delivery flow rate of pressure oil, which is to be delivered from at least one of variable displacement hydraulic pumps (2a-2f) to a hydraulic actuator, according to a lever stroke from one of control devices 40a,40b and corresponding one of preset efficiency values set beforehand for the hydraulic pumps.

Abstract: A pump controller causes a first plunger pump and a second plunger pump connected in series or in parallel to perform intake and compression actions alternately at substantially constant cycles, sets a pressurizing chamber of one of the plunger pumps to a state of a higher pressure than the pressurizing chamber of the other plunger pump, and performs flow rate control by adjusting lift amounts of the first plunger and the second plunger. Thus, it is possible to provide a pump for liquid chromatograph, and a liquid chromatograph, which are capable of reducing pulsations even when an ejection flow rate is changed.

Abstract: Closed circuit lines (33, 43, 53, 63) for connecting hydraulic cylinders (17, 18, 19) and closed circuit pumps (31, 41, 51, 61) are provided with a charge pressure adjustment apparatus (75) via a charge line (72) to variably adjust the pressure in the charge line (72). An operating device (12) for operating the hydraulic cylinders (17, 18, 19) and the charge pressure adjustment apparatus (75) are connected to a control device (81). In the case of extending the hydraulic cylinders (17, 18, 19), the control device (81) increases a set pressure of the charge pressure adjustment apparatus (75) to be high to increase the pressure in the bottom side of the hydraulic cylinders (17, 18, 19) in accordance with an operating amount of the operating device (12).

Abstract: To provide a driving device capable of improving the operability of a plurality of single rod hydraulic cylinders. The present invention takes a construction provided with a closed circuit A in which first and third hydraulic pumps 12, 14 and a boom cylinder 1 are connected through selector valves 43a, 45a in a closed-circuit fashion, a plurality of open circuits E, F provided with second and fourth hydraulic pumps 13, 15 and selector valves 44a, 46a that switch the supply destinations of hydraulic oils flowing out from the second and fourth hydraulic pumps 13, 15, and a connection passage 301 connected to sides of the selector valves 44a, 46a from which sides hydraulic oil flows out, and connected to the closed circuit A.

Abstract: Provided is a driving device for a working machine, which can drive one or more hydraulic pumps in a large capacity range of as high efficiency as possible. In a driving device for a hydraulic excavator, a controller (41) is provided with a first target delivery-flow-rate setting unit (41a) that computes a first target delivery flow rate of pressure oil, which is to be delivered from at least one of variable displacement hydraulic pumps (2a-2f) to a hydraulic actuator, according to a lever stroke from one of control devices 40a,40b and corresponding one of preset efficiency values set beforehand for the hydraulic pumps.