Created on:2021-12-07 13:32

Function, classification and working principle of hydraulic pump

Function, classification and working principle of hydraulic pump

1. Function, classification and working principle of hydraulic pump

In the hydraulic transmission system, the hydraulic pump is the power component of the hydraulic transmission system. It is an energy conversion device that converts the mechanical energy input by the prime mover (such as motor) into liquid pressure energy. In the hydraulic transmission system, it belongs to the power element and is an important part of the hydraulic transmission system. Its function is to provide pressure oil to the hydraulic system.

There are many kinds of hydraulic pumps. According to their different structural forms, they can be divided into gear type, blade type, plunger type and screw type; According to whether the displacement of the pump can be changed, it can be divided into quantitative pump and variable pump; According to whether the output oil direction of the pump can be changed, it can be divided into one-way pump and two-way pump. The commonly used hydraulic pumps in engineering include gear pump, vane pump and plunger pump; The gear pump comprises an external meshing gear pump and an internal meshing gear pump; Vane pump includes double acting vane pump and single acting vane pump; The plunger pump consists of and.

2. Working principle of hydraulic pump

In hydraulic transmission, hydraulic pumps work by changing the sealing working volume, so they all belong to positive displacement pumps.

The working principle of the hydraulic pump is shown in Figure a. The plunger 2 is tightly pressed on the eccentric 1 under the action of spring 4. When the eccentric 1 rotates, the plunger moves back and forth. When the plunger moves to the right, a certain vacuum is formed due to the increase of the volume of the sealing chamber a, and the oil is sucked from the oil tank through the check valve 6 under the action of atmospheric pressure. At this time, check valve 5 closes the oil pressure port to prevent the system oil from flowing back; When the plunger moves to the left, the volume of the sealing chamber a decreases and the sucked oil is pressed out through the check valve 5. At this time, the check valve 6 closes the oil suction port to prevent the oil from flowing back into the oil tank. If the eccentric wheel l keeps rotating, the pump will continuously carry out the process of oil suction and pressure. It can be seen that the hydraulic pump works by the change of sealing volume, so it is often called positive displacement hydraulic pump. Check valves 5 and 6 are necessary oil distribution devices to ensure normal oil suction and pressure of hydraulic pump.

The graphic symbols of the hydraulic pump are shown in Figure B.

It can be seen from figure a that no matter what the specific structure of the hydraulic pump is, it must meet three working conditions: ① it must have a closed and changeable volume to complete the oil absorption and drainage process; ② There must be a flow distribution device to separate oil suction and oil discharge; ③ The oil tank must be connected to the atmosphere to form a pressure difference and facilitate oil absorption.

The hydraulic motor also depends on the change of sealing volume. The working principle of hydraulic motor is reversible with that of hydraulic pump in theory, and their structure is basically the same; However, due to their different work tasks and specific requirements, only a few hydraulic pumps can be used as hydraulic motors in the actual structure.

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