External Factors Affecting Service Life of Hydraulic Pump

Affect the life of the hydraulic pump many factors, in addition to its own pump design, manufacturing factors and some related to the use of pumps (such as couplings, filters, etc.) of the selection, the operation of the test run and so on. This article puts forward my own understanding.

Related components of the analysis?

1 coupling?

(1) the choice of coupling Hydraulic pump shaft can not withstand radial forces and axial forces, it is not allowed to directly install the pulley, gears, sprockets at the shaft end, usually with a coupling coupling drive shaft and pump drive shaft . As a result of manufacturing reasons, the coaxial pump and coupling excessive, there are deviations in the assembly, with the pump speed increase the centrifugal force to increase the deformation of the coupling, deformation and centrifugal force increases, resulting in a vicious circle, the result Produce vibration noise, thus affecting the pump life. In addition, there are other factors such as the loose coupling of the coupling pin is not timely fastened, the rubber ring wear is not timely replaced.

(2) The assembly requirements of the coupling rigid shaft coupling coaxial error ≤ 0.05mm;
Elastic coupling axis of the coaxial error ≤ 0.1mm;
Two-axis angle error <1 °;
Drive shaft and pump end should be kept 5 ~ 10mm distance. ?

2 hydraulic tank?

(1) the choice of hydraulic tank
Hydraulic tank in the hydraulic system's main role for the storage of oil, heat, separating the air contained in the oil and eliminate foam. Select the first tank to consider its capacity, the general mobile device to take the pump the maximum flow of 2 to 3 times, fixed equipment to take 3 to 4 times; secondly consider the fuel tank level, when the system after all the hydraulic cylinders out of the tank surface should not be low At the lowest oil level, when the cylinder is retracted, the oil level should not be higher than the maximum oil level. Finally, considering the structure of the fuel tank, the partition in the conventional fuel tank can not act as sediment dirt. A vertical partition should be installed along the longitudinal axis of the fuel tank, Leaving a gap between one end of the separator and the end plate of the fuel tank so that the space between the two sides of the separator is communicated with the hydraulic oil pump inlet and outlet ports arranged on both sides of the non-communicating end separator so that the distance between the inlet oil and the oil return farthest, Hydraulic tank to play some cooling effect.

(2) hydraulic tank installation
According to the different installation location can be divided into on-type, side-type and under-set.

On the type of tank to install hydraulic pumps and other devices with a good stiffness on the cover, its compact structure, the most widely used. In addition, heat dissipation fins can be cast on the fuel tank shell to enhance the heat dissipation effect, that is, the service life of the hydraulic pump is increased.

Side-mounted tank is the hydraulic pump and other devices installed in the tank next to the large area, but the installation and maintenance are very convenient, usually when the system flow and fuel tank capacity is large, especially when a tank to more than one hydraulic pump Used for oil supply. Due to the side tank oil level higher than the hydraulic pump suction port, it has better oil absorption.

Under-tank is placed under the hydraulic pump under the tank, not only easy to install and repair, and hydraulic pump greatly improved suction capacity. ?
3 filter?

(1) filter selection
Pollutants with a particle size of less than 10 μm generally have less effect on the pump, while those with a diameter of more than 10 μm, especially at 40 μm, have a significant effect on the service life of the pump. The solid particles in the hydraulic oil can make the surface of the relative moving parts in the pump more aggravate. Therefore, the oil filter needs to be installed to reduce the pollution degree of the oil. Filtration requirements: axial piston pump 10 ~ 15μm, vane pump 25μm, gear pump 40μm. Pump pollution and wear can be controlled within the allowable range. At present, the use of high-precision oil filter is increasingly widespread, which can greatly extend the service life of the hydraulic pump.

(2) oil filter installation
Points in the following three cases: ① oil filter oil filter structure is simple, its role is to prevent oil absorption larger particles of pollutants into the pump, the general use of low-precision filter, the maximum filtration accuracy of not more than 30 ~ 50μm, in order to facilitate maintenance It is advisable to install the oil filter on the top or side of the tank, and the flow capacity of the oil pump should be considered more than twice the maximum flow rate of the pump to prevent the pump from sucking air. (2) The pressure oil filter is installed on the downstream pressure pipe Road, the hydraulic system to deliver clean pressure oil, usually using high-precision oil filter, the filtration accuracy of 3 ~ 20μm, the flow capacity should not be less than the maximum pressure of the oil flow; ③ Return oil filter installed in the total oil return pipe , The outside world invades the system and the pollutants generated in the system filter, usually also use high-precision oil filter. According to the recent pollution control system theory, the oil tank should reach a certain level of cleanliness. At the same time, in order to prevent over-pressure of the oil filter due to blockage, the filter should be installed to block the sender so as to timely replace the filter.

4 stop valve?

When disassembling the hydraulic pump and return line, the oil in the system will flow backwards. If the hydraulic pump with a load of parking will cause the hydraulic pump to reverse, making the pump suction pipe to produce a partial vacuum, dissolved in the oil in the air out, until the next drive the system will be mixed with air, noise, cavitation, shortened Pump life, for which a stop valve is usually installed not far from the hydraulic pump drain. The stop valve should also be set to indicate that the valve has been opened electrical signal switch and only when the valve is fully open hydraulic pump to start the interlock device to ensure that the pump is not suction air when driving. ?

5 heat exchanger?

Hydraulic system allows the oil temperature is 15 ~ 80 ℃, the best temperature is 25 ~ 55 ℃. Hydraulic system work inevitably have to produce mechanical loss, pressure loss and volume loss, all of these losses into heat, with the exception of some of the heat through the tank, the pipe is distributed to the surrounding space most of the heat to make the tank temperature. If the oil temperature is too high, the oil will deteriorate and precipitate asphalt and other debris. The viscosity of the oil will drop. The internal and external leakage of the hydraulic pump will increase. The lubricity of the oil is poor. The oil film will be easily damaged. The wear of the sliding parts in the pump will be aggravated. Service life, so the system temperature rise is too high, you must set the oil cooler. Cooler is divided into air-cooled, water-cooled and ice-cold, depending on the choice of use.

Conversely, if the oil temperature is too low, the oil viscosity increases, the frictional resistance increases, the hydraulic pump starts, oil absorption difficulties, affecting the use of the pump. In the area below 0 ℃ before starting the pump should be heated to 15 ℃ and above the oil and pass to the pump until the temperature of the components rose above 15 ℃ and then start the hydraulic pump, which requires the level of the bottom of the tank to set a heater to Guarantee always soaked in oil below. ?

6 operation precautions?
(1) before running ① hydraulic pump installation is accurate and reliable, the screws are tightened, the coupling installation meets the requirements;
② pump body filled with oil;
③ whether the steering pump and inlet and outlet match;
④ hydraulic system safety valve is transferred to the specified pressure value. ?

(2) in operation
Start at full speed can not be started quickly, the system should be unloaded state Jog switch the prime mover continuous operation at no load, the purpose is to exclude the air pipe as clean as possible, no-load operation 1 ~ 2min no abnormalities Gradually loaded, there should be no abnormal vibration during loading, noise and leakage, or immediately shut down inspection and analysis, troubleshooting. ?

(3) After the operation is over
If the pump should not be long-term release of the pump fluid, and then filled with a lower acid value of the oil, the exposed surface coated with anti-rust oil, the oil port sealed with screw plug to prevent dirt into.
From the above analysis we can see that the life of the hydraulic pump is damaged by its own internal parts, the degree of wear and tear and its decision, but its internal parts damaged, the degree of wear and tear directly affected by the use of external components, the rational use of hydraulic pump related external components, the correct operation Using a hydraulic pump can greatly improve the life of the pump.