| The traditional cooling system of 50 type wheel loader machine has a mutual interference between radiators, poor air circulation status and not ideal cooling effect. In this paper, the design of the two-circuit cycle cooling system is to solve the heat dissipation problem in wheel loader described above. The cooling system in this paper can improve the cooling effect of the cooling system, so that each heat source could be in a thermal equilibrium state. In this paper, a onedimensional simulation model of two-circuit cycle cooling system is built on AMESim platform, and the influence factors and heat dissipation performance of the cooling system are analyzed. The main work contents are as follows.Firstly, the fan speed control model is deduced in this paper. The main heat source condition of the 50 wheel loader is analyzed. Heat dissipation characteristics and resistance characteristics of the high temperature and low temperature radiator which can be connected in series or parallel mode is calculated by ε- NTU method according to the parameters of the radiator structure and size. The fan used in the system is selected by the Multi-Wing company’s fan selection software. The static pressure and power of the fan can be drawn according to the data provided by Multi-Wing company to fit the characteristics of the fan at different speed. Fan speed regulation for scheme A and B is derived according to the heat balance principle for high temperature radiator with the change of the environment temperature.Secondly, the two-circuit cycle cooling system model was established based on the AMESim software platform and the factors affecting the cooling effect of the two-circuit cycle cooling system were studied. Hydraulic pumps, hydraulic motors and valves of the system are selected. The system simulation model of scheme A and B is built in the AMESim software platform, which is divided into the quantitative driving model and the variable driving model according to the low temperature circulating cooling fluid drive mode. The heat dissipation effect of the flow rate of the cooling fluid and the relative position between the radiators is studied. The power consumption of different two-circuit cycle cooling system driving modes is analyzed. The scheme A drive mode hydraulic pump power consumption is higher than the scheme B drive mode of the power consumption of the hydraulic pump. The power of the hydraulic pump driven by the quantity of the hydraulic pump is higher than that of the variable.Finally, the heat dissipation performance of the two-circuit cycle cooling system is analyzed. According to the plan A and B under different engine throttle state, combined with changes in ambient temperature, respectively on the quantitative pump driving mode and variable pump drive mode, the radiating effect of the high temperature cycle and hypothermic circulatory simulation analysis, each heat source radiator heat dissipation and thermal fluid outlet temperature changes. In view of the different operation stages of V type operating conditions, the heat generation of each heat source is different, and the dynamic simulation of the A and B double cycle cooling system is carried out.The number of radiators in the two-circuit cycle cooling system is reduced to two, that can reduce the air resistance of the radiators and solve the problem of air flow heterogeneity between the radiators. The hydraulic motor of fan is driven by the low temperature circulating hydraulic pump. Low temperature coolant not only acts as cooling medium, but also provides mechanical energy for fan, that simplifying the structure model. Fan speed can be adjusted according to the working conditions and the environment temperature. |
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