Hydraulic pump is a hydraulic system of power components, its role is to convert the mechanical energy of the prime mover into liquid pressure energy, refers to the hydraulic system in the oil pump, which provides power to the entire hydraulic system. The structure of the hydraulic pump are generally gear pump , vane pump and piston pump .
The principle of a hydraulic pump is a hydraulic element that provides pressurized fluid for a hydraulic drive and is a type of pump. Its function is to convert the mechanical energy of power machines (such as electric motors and internal combustion engines) into liquid pressure energy. The figure for the single plunger pump works. Cam driven by the motor rotation. As the cam pushes the plunger up, the seal formed by the plunger and the cylinder decreases in volume, the oil is squeezed out of the sealed volume and drained through the check valve to where it is needed. When the cam rotates to the descending part of the curve, the spring forces the plunger down to create a degree of vacuum, and the oil in the tank enters the sealed volume at atmospheric pressure. The cam continuously raises and lowers the plunger, periodically reduces and increases the volume of the seal, and the pump continues to suck and drain oil.
1, the phenomenon of shortcomings and analysis of the reasons from the following three points in the maintenance of the reasons for the shortcomings, and stop the system to improve:
(1) check the boom cylinder leakage situation. The easiest way is to raise the boom to see if it has a clear free fall. If the whereabouts of obvious removal of the fuel tank inspection, seals have been worn should be changed.
(2) Check the control valve. First clean the safety valve, check whether the spool wear, such as wear and tear should be changed. If there is still no change after the installation of safety valve, and then check the control valve spool wear, the gap of the general use of 0.06mm, serious wear and tear should be changed.
(3) measure the pressure of the hydraulic pump. If the pressure is low, then stop the adjustment, the pressure is still not adjustable, the serious wear and tear of the hydraulic pump.
In general, the main reason that the boom loading can not be improved is:
a. Hydraulic pump is severely worn. The pump is revealed seriously at low speed; pump pressure is slightly improved at high speed, but due to pump wear and internal leakage, the volumetric efficiency drops significantly and it is difficult to reach the rated pressure. Hydraulic pump work for a long time has exacerbated the wear and tear, oil temperature rise, which constitutes the hydraulic components wear and seal aging, damage, loss of sealing ability, the hydraulic oil metamorphosis, and finally incurred shortcomings.
b. Hydraulic components selection is not reasonable. Boom cylinder specifications for the 70/40 non-standard series, the seal is also a non-standard parts, the high cost of the system and seal replacement inconvenience. Boom cylinder bore is small, the system is bound to set high pressure.
c. Hydraulic system design is not reasonable. Control valves and full hydraulic steering gear for a single pump in series, safety valve setting pressure points 16MPa, while the hydraulic pump rated working pressure is also 16MPa. Hydraulic pump often work at full load or prolonged overload (high pressure), and the system has a hydraulic impact, long-term oil does not change, the hydraulic oil contaminated, exacerbating the hydraulic pump wear, resulting in hydraulic pump casing burst (was found Such shortcomings).
2, improvement and effect (l) to improve the hydraulic system design. After several demonstrations, the final use of advanced priority valve and load sensing hydraulic steering system, the new system can follow the steering request, give priority to the distribution of traffic, regardless of the size of the load, the steering wheel speed up and down to ensure adequate supply of oil, the remaining part Can all be supplied to the working device circuit, thereby eliminating the power loss caused by excessive oil supply to the steering circuit, improving the system efficiency and reducing the working pressure of the hydraulic pump.
(2) Optimize the design of boom cylinder and hydraulic pump and reduce the pressure of system work. After optimization calculation, the boom cylinder adopts standard series 80/4. Hydraulic displacement of 10ml / r progress to 14ml / r, the system set pressure of 14MPa, to meet the booster cylinder lift and speed requirements.
(3) In the process of using the loader should also pay attention to the proper use and maintenance, regular addition or replacement of hydraulic oil, hydraulic oil to maintain cleanliness and strengthen daily inspection and maintenance.