Hydraulic pump selection and working characteristics

First, the choice of hydraulic pump

The hydraulic pump is a hydraulic component that provides a certain flow and pressure, and is an indispensable core component of each hydraulic system. Reasonable selection of the hydraulic pump reduces the energy consumption of the hydraulic system, improves the efficiency of the system, reduces noise, and improves work performance. It is very important to ensure the reliable operation of the system.

The basic factors to consider when selecting a hydraulic pump include:

(1) Safety pressure and maximum working pressure of the system.

(2) Permissible speed of the hydraulic pump.

(3) Hydraulic pump calibration characteristics.

(4) The required flow rate of the hydraulic system.

(5) The relationship between pressure, speed, and flow.

(6) Adaptability of variable control.

(7) Tolerance to pressure shock.

(8) The degree of leakage loss.

(9) Volumetric efficiency and total efficiency.

(10) Contamination tolerance.

(11) Operational reliability and durability.

(12) Life expectancy at various loads and speeds.

(13) The characteristics of the oil and its relationship to the wear rate of the hydraulic pump.

(14) Suction conditions.

(15) maintainability.

(16) The compatibility, cost, and economics of the entire system.

The principle of choosing the hydraulic pump is: according to the main engine working condition, the size of the power and the requirements of the system to the working performance, first determine the type of the hydraulic pump, and then determine the required pressure and flow size of the system. The choice of hydraulic pump not only considers pressure, flow, volume, and cost, but other aspects are also important. For example, the hydraulic pump system compatibility, pump reliability and its expected life.

For low-pressure, medium- and high-pressure use cases, the external gear pump is cheaper than other pumps in terms of economy, but as the pressure increases and the use time increases, the noise value increases sharply. If the pressure and noise of the vane pump are small, it is more suitable than the external gear pump under the condition of fixed medium pressure. Its total efficiency is lower than that of the piston pump. Experience has shown that the use of screw pump pressure in 2 - 3 MPa is very economical, this pump is not the quietest pulsation, when the oil exclusion of appropriate, high reliability coefficient. Radial piston pumps have a long life expectancy and are suitable for high pressure applications. Axial piston pump operating pressure of 20 - When 25 MPa, life expectancy of 40000h, when the operating pressure is 30 - When 35MPa, its life will be reduced to 15000h.

The above factors should be considered one by one when selecting the pump, so that it has a corresponding adaptability, and the hydraulic pump can be operated reliably in the system, otherwise various failures will occur.

Second, the hydraulic pump work features:

( 1 ) If the suction pressure of the hydraulic pump is too low, it will result in insufficient oil absorption, abnormal noise, and even no work. Therefore, in addition to minimizing the hydraulic resistance of the oil suction pipe in the structural design of the pump, in order to ensure the normal operation of the pump, the installation height of the pump should not exceed the allowable value; avoid excessive formation of the oil filter and piping The pressure drop; limit the use of pump speed to within the rated speed.

( 2 ) The working pressure of the hydraulic pump depends on the external load. If the load is zero, the working pressure of the pump is zero. As the oil discharge increases, the working pressure of the pump automatically increases according to the load. The maximum working pressure of the pump is mainly limited by the structural strength and service life. In order to prevent the pump and system from being damaged due to excessive pressure, the outlet of the hydraulic pump is often subject to pressure limiting measures.

( 3 ) The variable pump can change the flow rate by adjusting the displacement. The quantitative pump can only adjust the flow rate by changing the rotation speed, but the increase of the rotation speed is limited by the oil absorption performance, the service life of the pump, and the efficiency. For example, when the operating speed is low, although it is advantageous for the life, the volumetric efficiency is reduced, and for a vane pump that needs to operate with centrifugal force, if the rotational speed is too low, normal operation cannot be guaranteed.

( 4 ) The flow rate of the hydraulic pump has a certain degree of pulsation, and the pulsation condition depends on the pump type and structural design parameters. In order to reduce the influence of the pulsation, in addition to the styling considerations, an accumulator or a hydraulic filter may be provided in the system if necessary.

( 5 ) The hydraulic pump sucks and discharges oil by changing the volume of the working chamber. If the working chamber is in the transitional sealing zone between suction and discharge, there will be a change in volume, which will result in a sudden increase or decrease in pressure. Phenomenon", which affects the volumetric efficiency, generates pressure pulsations, noise, and additional dynamic loads on the working member. This is a common problem that needs attention in the design of hydraulic pumps.

Third, the hydraulic pump recommended

Germany Lucas dual output hydraulic motor pump

product description:

The German Lucas dual-output hydraulic motor pump is a light hydraulic power source for the LUKAS hydraulic rescue tool. It can connect and use two tools at the same time.

Germany Lucas dual-output hydraulic motorized pump is a brand-new design product. The surrounding pump frame protection design can not only ensure the safe use of the pump, but also facilitate the transportation. It has double flow function, which can speed up the rescue.

Features:

1. Compact and compact shape, easy to handle;

2. The liquid level of the tank is more convenient to operate;

3. Around the frame protection design can ensure that the pump is safer and can be easily handled;

4. With double flow function, this feature can make rescue tools faster;

5. Dual output, fast interface.

This article is edited and compiled by China Rescue Equipment Network. Please indicate the link.