The Research On High-temperature Problems Of Wheel Loader Hydraulic System

The cooling fan of ZL50 wheel loader is driven via traditional crankshaft fixed transmission ratio, and this fan is also used to cool down the engine and hydraulic oil of mechanical transmission, operation and steering systems so that its heat dissipation intensity is quite great. The driving method of the cooling fan increases the start torque of engine, prolongs the preheating time, causes under cooling at low-speed and high-load and overcooling at high-speed and low-load, and thus results in unreasonable cooling of engine and more power consumption by the fan, decreases the power output of engine, and limits the fix location of the fan which makes high operation noise.This research is an improvement to design of cooling system of ZL50 wheel loader. Considering the structure feature of ZL50 wheel loader, on the basis of actual project research, we change the arrangement of radiator of low-end products and adopt SCM (single chip micyoco) to control the fan of high-end products by means of advanced and mature technologies in vehicle engine, thus fulfill the objective of automatic adjustment of cooling capability of wheel loader as needed, and avoid deficiency of its cooling ability at high working temperature and under high load.This article mainly covers the cooling system operating principle, influence of arrangement of radiator on cooling system, parameter calculation and selection of main hydraulic elements of the hydraulic drive system of the cooling device on the engine, selecting and matching of proportional spill valve, hardware circuit design and software design of SCM control system, etc.In conclusion, this research shortens the warm-up time of wheel loader at low temperature, increases its efficiency, boosts up adaptability of cooling system of the wheel loader in different working conditions, improves the working condition for wheel loader to work under high temperature and significantly increases the ability of the machine to work continuously for a long time. It will be of great importance to apply this technique to domestic wheel loader and other engineering machine.