Electromagnetic switching double-displacement pump

Abstract

The invention relates to an electromagnetic switching double-displacement pump comprising a changeable displacement pump, an electromagnetic reversing valve and a displacement switching device. The displacement switching device comprises a fluid-pressure driving mechanism and a displacement resetting mechanism. A driving end of the fluid-pressure driving mechanism and a movable end of the displacement resetting mechanism are respectively positioned in two control ends of a capacity regulating mechanism of the changeable displacement pump. A decompressing mechanism comprising a three-way overflow decompressing valve and a throttle pipe is arranged between an output port of the electromagnetic reversing valve and an input port of the displacement switching device. The input port of the three-way overflow decompressing valve is connected to the output port of the electromagnetic reversing valve. The output port of the three-way overflow decompressing valve is connected to the input port of the fluid-pressure driving mechanism. The throttle pipe is connected to a place between the output port of the three-way overflow decompressing valve and a pressure control port. An oil discharging port of the three-way overflow decompressing valve is connected to a reflow port of a fluid-pressure tank PT. The electromagnetic switching double-displacement pump with the structure has the advantages of good running stability, quick decompressing action response and high control precision.

Description

technical field [0001] The invention relates to a hydraulic pump used in a hydraulic control system, in particular to an electromagnetically switched double-displacement pump capable of switching large and small displacements through a three-way decompression valve. Background technique [0002] The hydraulic pump is a device that is powered by the prime mover and sends hydraulic oil to the hydraulic circuit. It provides a certain fluid pressure and flow to the actuators of the hydraulic system and is an essential component of the hydraulic system. Since the working state of the hydraulic system changes at any time, the flow and pressure required by the actuator change accordingly. In the hydraulic system of the hydraulic pump with fixed displacement, the excess power is shunted off through throttling and overflow. With the development of control technology, a pressure-flow composite proportional valve has emerged to comprehensively control the system pressure and flow. Sub...

AI Technical Summary

Problems solved by technology

Now a large number of servo motors are used to drive fixed-displacement hydraulic pumps. By detecting the output pressure of the hydraulic pumps, the computer calculates, and then the computer issues instructions to adjust the speed of the servo motor. The defect of this system is: under high pressure and low flow , the driving torque of the servo motor is still very large, because of the characteristics of the servo motor, the current of the motor is very large at this time, and the heat is more, causing a lot of waste

The variable capacity pump with this structure can be switched through external signals according to the flow demand of the hydraulic system, so that the electromagnetic switching double displacement pump works at the upper limit of displacement and the lower limit of displacement respectively, and the control of its output flow and pressure The servo system is responsible for switching the displacement of the pump when a certain flow rate critical value or a certain working condition switching point is reached, so that the servo system can work in a better state, effectively saving and reducing the cost of electromagnetic switching double displacement pumps. energy consumption, but the throttle tube is used as the decompression mechanism, the response is slow, the reaction is not sensitive and the pressure is not easy to control, resulting in a large switching force of the displacement switching device, and excessive driving force is likely to cause deformation of the relevant parts. Moreover, the pressure at the oil discharge port is unstable and the control accuracy is low, which directly affects the stability of the switching force of the displacement switching device, which in turn affects the working stability of the variable capacity pump.

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