Nowadays, the cooling system of hydraulic excavator is developing in the direction of lightweight, compact, energy saving and intelligent. Radiator is the core of the engine cooling system of hydraulic excavator. If the cooling system can not work normally, it will cause many adverse factors to the hydraulic and power system.
If the cooling capacity of the cooling system is too low, it will cause the following problems:
1. The viscosity of hydraulic oil is reduced, resulting in leakage, oil vaporization, aggravating the "cavitation" phenomenon, and the hydraulic system can not work normally.
2. The rigidity and strength of piston decrease, and it is easy to deform or break.
3. The lubricating oil is ablated, which leads to the poor operation of the lubricating system and the dry friction between the components, reducing the service life of the engine.
4. The air intake is reduced, which reduces the output power of the engine.
If the cooling efficiency of the cooling system is too high, the following problems will occur:
1. The engine power output is reduced and the power is insufficient.
2. Poor fuel atomization increases fuel consumption.
3. The lubrication performance of the engine is reduced, the friction is increased, the noise is increased, and the service life of the engine is reduced.
4. When the water temperature is too low, the engine starting resistance increases and the starting performance decreases.
Although the engine direct drive cooling system can improve the cooling efficiency of the cooling system to a certain extent by improving the radiator structure and optimizing the matching of the cooling system, the fan speed can not be flexibly changed according to the cooling demand, so it is unable to provide an appropriate solution for different heat dissipation requirements at the same engine speed.
Independent cooling control technology uses independent hydraulic fan pump to control the fan motor, and then controls the heat dissipation power of the radiator. It can control the speed of the fan motor according to different cooling needs. The influence of engine speed change on fan speed is weakened and the fan runs smoothly, which can effectively solve the power interference problem under the condition of high engine speed and low heat dissipation demand. The motor speed, power loss and noise of radiator can be reduced by reducing the displacement of fan pump. When the engine speed is low and the cooling demand is large, the power of the cooling system can be improved by increasing the displacement of the fan pump without changing the engine speed to meet the cooling demand.
