Patent application number | Description | Published |
20110173964 | HYDRAULIC DRIVE SYSTEM FOR CONSTRUCTION MACHINE - A main relief valve | 07-21-2011 |
20120031088 | HYDRAULIC DRIVE SYSTEM FOR CONSTRUCTION MACHINE - A hydraulic drive system for a construction machine allows automatic changes of the operational characteristics of a boom directional control valve by judging whether or not a hydraulic boom cylinder needs driving pressure at the time of a boom lowering operation. | 02-09-2012 |
20130055705 | HYDRAULIC DRIVE SYSTEM FOR CONSTRUCTION MACHINE - A hydraulic drive system for a construction machine has a travel detection device which detects whether or not the operation mode is a traveling operation and a setting changing device. The setting changing device sets the target differential pressure of load sensing control at an absolute pressure Pa when the operation mode is not a traveling operation, and sets the target differential pressure of the load sensing control at an absolute pressure Pa′ rather than the absolute pressure Pa. In this way, in the actuator operation other than traveling, a necessary actuator speed can be obtained and supplied with the necessary maximum flow rate. In addition, during the combined operation, a flow rate in accordance with the opening area ratios of flow control valves can be distributed to actuators different in load pressure from one another; and energy efficiency is enhanced due to less energy loss during traveling operation. | 03-07-2013 |
20130152573 | HYBRID SYSTEM FOR CONSTRUCTION MACHINE - When the actuator drive torque of a hydraulic pump is lower than a switching torque τ0, a controller closes a solenoid switching valve and makes a rotary electric machine function as a generator. With the increase in the actuator drive torque, the controller controls a pressure compensated flow control valve so that the flow rate of hydraulic fluid supplied from the hydraulic pump to a rotary hydraulic device decreases. When the actuator drive torque is higher than the switching torque, the controller opens the solenoid switching valve, makes the rotary electric machine function as an electric motor, and controls the pressure compensated flow control valve so that the hydraulic fluid discharged by the hydraulic pump is not supplied to the rotary hydraulic device. Consequently, shocks due to flow rate fluctuation are prevented when operational states of the rotary hydraulic device and the rotary electric machine are switched. | 06-20-2013 |
20130227936 | HYDRAULIC DRIVE SYSTEM FOR CONSTRUCTION MACHINE HAVING EXHAUST GAS PURIFICATION DEVICE - A hydraulic drive system executing load sensing control is capable of efficiently combusting and removing filter deposits inside an exhaust gas purification device by pump output power increasing control when there is no actuator operation, eliminating interference between the actuator operation and the pump output power increasing control. A first solenoid selector valve selects between tank pressure and delivery pressure of a pilot pump. A second solenoid selector valve is arranged in a line leading the output pressure of a differential pressure reducing valve to an LS control valve for selecting between enabling and disabling of the load sensing control. When the exhaust gas purification device needs regeneration, a controller executes switching to make the first solenoid selector valve output the delivery pressure of the pilot pump as dummy load pressure and to make the second solenoid selector valve disable the load sensing control. | 09-05-2013 |
20130287601 | HYDRAULIC DRIVE SYSTEM FOR WORKING MACHINE INCLUDING TRACK DEVICE OF CRAWLER TYPE - 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. | 10-31-2013 |
20140046552 | ELECTRIC DRIVE UNIT FOR CONSTRUCTION MACHINE - An electric drive unit for a construction machine is capable of increasing the operating time of the construction machine. The electric drive unit has an electricity storage device, a hydraulic pump of the fixed displacement type which is driven by a motor/generator, a plurality of directional control valves which respectively control the flow of hydraulic fluid supplied to a plurality of hydraulic actuators, a bidirectional converter which performs variable control on the revolution speed of the motor/generator, and an LS control device which controls the bidirectional converter so that LS differential pressure Pls equals a target value Pgr. The bidirectional converter performs regeneration control for converting the inertial force of the rotor of the motor/generator into electric power thereby charging the electricity storage device when the revolution speed of the motor/generator is decreased in response to an excess of the LS differential pressure Pls over the target value Pgr. | 02-13-2014 |
20140052350 | ELECTRIC DRIVE UNIT FOR CONSTRUCTION MACHINE - An electric drive unit for a construction machine is capable of increasing the operating time of the construction machine. The electric drive unit has an electricity storage device, a hydraulic pump of variable displacement type which is driven by a motor/generator, a regulator which performs variable control on the displacement volume of the hydraulic pump, a bidirectional converter which performs variable control on the revolution speed of the motor/generator, and an LS control device which controls the regulator and the bidirectional converter so that LS differential pressure Pls equals a target value Pgr. The bidirectional converter performs regeneration control for converting the inertial force of the rotor of the motor/generator into electric power thereby charging the electricity storage device when the revolution speed of the motor/generator is decreased in response to an excess of the LS differential pressure Pls over the target value Pgr. | 02-20-2014 |
20140165543 | CONSTRUCTION MACHINE HYDRAULIC DRIVE SYSTEM HAVING EXHAUST GAS PURIFYING DEVICE - A construction machine hydraulic drive system that performs load sensing control is capable of efficiently burning and removing deposits on a filter in an exhaust gas purifying device through pump output increasing control and to be free from faults in the pump output increasing control even when an actuator is operated during the pump output increasing control. A solenoid switching valve is switched so that output pressure of an engine speed detecting valve is guided to a pressure receiving portion of an LS control valve and a pressure receiving portion of an unloading valve when a start of regeneration is not directed, and delivery pressure of a pilot pump is guided to the pressure receiving portion and the pressure receiving portion when the start of the regeneration is directed, to thereby disable load sensing control to increase capacity of a main pump and increase set pressure of the unloading valve. | 06-19-2014 |
20140174068 | HYDRAULIC DRIVE SYSTEM FOR CONSTRUCTION MACHINE - A hydraulic motor ( | 06-26-2014 |
20150027112 | HYDRAULIC DRIVE SYSTEM FOR CONSTRUCTION MACHINE - Pressure compensating valves not fully closing at the stroke end are employed, and upon the operators operation for the traveling, pilot primary pressure is reduced and supplied to remote control valves | 01-29-2015 |
20150040553 | HYBRID WORKING MACHINE - Pressure sensors are provided to detect the delivery pressure of a hydraulic pump, the output pressure of an engine revolution speed detecting valve, and the output pressure of a differential pressure reducing valve generating the differential pressure between the delivery pressure of the hydraulic pump and a maximum load pressure. A vehicle controller calculates virtually the displacement of the hydraulic pump by use of the detected pressures and an equation of motion about a swash plate of the hydraulic pump, calculates the power need of the hydraulic pump and the output of the engine using these values, and switches a motor between powering and generation control in accordance with the result of a comparison between the pump power need and the engine output. In this manner, the displacement of the hydraulic pump without using sensors to detect the tilting angle of the swash plate of the hydraulic pump. | 02-12-2015 |