摘要:
A header is supported by a pair of hydraulic float cylinders, where a float pressure to the cylinders is directly controlled by an electronic control supplying a variable control signal to a PPRR valve arrangement to maintain the float pressure at a predetermined value. At the set pressure a predetermined lifting force is provided to the header. A position sensor is used to generate an indication of movement and/or acceleration and/or velocity. The electronic control is arranged, in response to changes in the sensor signal, to temporarily change the control signal to vary the lifting force and thus change the dynamic response of the hydraulic float cylinder. A lift force greater than that required to lift the header can be provided by a lift cylinder and can be opposed in a controlled manner to apply a controlled downforce by the back of the same cylinder or by a separate component.
摘要:
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.
摘要:
This invention provides a hybrid construction machine including a swing structure, a hydraulic pump, a hydraulic swing motor driving the swing structure using hydraulic fluid from the hydraulic pump, an electric swing motor driving the swing structure in conjunction with the hydraulic swing motor, a boom cylinder operated simultaneously with the swing structure at times and driven by the hydraulic fluid from the hydraulic pump, a first directional control valve controlling flow of the hydraulic fluid supplied from the hydraulic pump to the hydraulic swing motor, a second directional control valve controlling the flow of the hydraulic fluid returning from the hydraulic swing motor, and a controller and solenoid pressure reducing valves which prevent operation of the second directional control valve when the boom cylinder is operated simultaneously with the swing structure.
摘要:
Hydraulic unit adapted for connection to master and slave actuator system includes three valves, the first configured for selective fluid passage between the cap ends, the second configured for selective fluid passage between the slave cap end and an accumulator, and the third fluidly coupled for selective fluid passage between each of a single pump and the accumulator, and the slave cap end. During actuator retraction, the valves permit pressurized fluid in the slave cap end to be delivered to accumulator for storage; during extension, the valves permit pressurized fluid from pump and accumulator to be delivered to the slave cap end.
摘要:
A method for operating a hydraulic system with a plurality of consumers an electrically controllable pressure supply device and an electrically actuable inlet valve, per consumer, which inlet valve is arranged between the pressure supply device and the consumer, wherein a pressure/volume relationship is predefined or determined for each consumer, wherein each consumer is assigned to a first group or a second group of consumers, wherein the first group of consumers includes at least one consumer, and wherein, in order to set predefined consumer-specific setpoint pressures, the first group of consumers is connected via the respectively opened inlet valve to the pressure supply device, and the inlet valves of the consumers of the second group are closed, wherein the inlet valve of a single, selected consumer of the second group is opened while being regulated to build up a pressure, and a brake system for motor vehicles.
摘要:
A control system for a hydraulic system including an accumulator and a hydraulic transformer coordinates flow sharing within the hydraulic system. The hydraulic transformer includes first and second variable displacement pump/motor units mounted on a rotatable shaft. The rotatable shaft has an end adapted for connection to a first external load. The first variable displacement pump/motor unit includes a first side that fluidly connects to a pump and a second side that fluidly connects to a tank. The second variable displacement pump/motor unit includes a first side that fluidly connects to the accumulator and a second side that fluidly connects with the tank. A second external load may be hydraulically connected to the hydraulic system. Energy may be transferred to/from the pump, the accumulator, the first external load, and/or the second external load, as directed by the control system.
摘要:
Hydraulically driven arrangement for the linear movement of a mass body consisting of two double acting cylinders coupled in parallel, whereby one operating cylinder is a control cylinder for controlling the movement of the mass body, which is split into an acceleration phase, a movement phase and a brake phase. The other operating cylinder is connected as a drive cylinder to the hydraulic power pack as an energy storage, in a manner that the power pack during the acceleration phase of the mass body generates the drive energy for the drive cylinder, and the drive cylinder in the brake phase of the mass body, which serves as a pump for charging the hydraulic power pack. The control cylinder and drive cylinder each have a piston with a one-sided piston rod coupled to the mass body. The control cylinder and the drive cylinder are controlled by hydraulically separated, independent control circuits.
摘要:
The invention relates to a hydraulic system having a pump and at least two working machines, in particular two working machines embodied as hydraulic cylinders. Each working machine is connected by pressure lines to the associated drive machine via two connectors that serve as an inflow or return. At least one valve is associated with each working machine, for adjusting the operating state of the working machine. In the context of an elevating work platform the connector which serves as an outflow in a working state of that working machine that is brought about or at least assisted by gravity is connected via a bypass, circumventing the drive machine, directly to the connector, serving as inflow in the context of a desired operating state, of another working machine, so that the hydraulic fluid flowing out from the first working machine flows for actuation of the other working machine.
摘要:
A hybrid system for a machine is disclosed. The system has a pump configured to generate fluid flow within a hydraulic system and a first actuator actuated by fluid pressurized by the pump. The system also has a first motor configured to be selectively actuated by pressurized fluid directed from the first actuator by an external load and directed to the first motor by a first control valve. The system further has a first generator configured to be actuated by the first motor and a power source configured to actuate the pump. The system also has a powertrain including a first driveshaft and at least one traction device, the powertrain configured to transfer kinetic energy from the traction device to the first driveshaft during deceleration of the machine. The system further has a second generator configured to be selectively actuated by the kinetic energy transferred by the powertrain.