| With the global energy shortage and environmental problems,the country’s requirements for vehicle emissions have become stricter.Energy-saving emission reduction and improving fuel economy have become the primary tasks of domestic automobile enterprises.As the most important part of the vehicle powertrain,the transmission system has a decisive influence on the efficiency of the vehicle transmission and the fuel consumption of the whole vehicle.In order to reduce the fuel consumption of a front-mounted front-drive SUV model,this paper starts with the research of this type of vehicle transmission system,in order to reduce the transmission resistance and improve the fuel economy of the vehicle.The main contents and conclusions are as follows:(1)Transmission resistance distribution of the whole vehicle.Using the chassis dynamometer and dismantling method to benchmark the transmission resistance of the vehicle and the resistance of the transmission components.The least square method is used to linearly fit the test results.According to the fitting results,the inherent mechanical friction resistance of the target vehicle is relatively large.Therefore,the transmission resistance split test was carried out later.The results show that the target vehicle has a large resistance to the transmission components such as the transmission,the brake and the hub bearing,and there is a large space for optimizing the resistance.(2)Analysis of factors affecting transmission resistance and optimization of resistance reduction.The theoretical analysis of the power loss under the load state and the non-load state of the target transmission gear is carried out.It is concluded that the factors such as gear and bearing precision,gear lubricating oil and bearing clearance are the key factors affecting the transmission resistance.Finally,according to the theoretical analysis results,the transmission transmission efficiency test is designed to explore the influence of the key factors on the transmission efficiency of the transmission,and the practical transmission transmission efficiency improvement scheme is obtained.(3)Analysis of factors affecting wheel bearing and brake resistance and optimization of resistance reduction.According to the theoretical analysis of the factors affecting the bearing resistance of the hub,it is shown that the viscosity of the grease,the bearing seal structure and the negative clearance are the main optimized resistance directions of the hub bearings.At the same time,according to the theoretical analysis of the factors affecting the brake resistance,the main optimized drag reduction direction of the brake is the deformation of the brake block and the brake disc.Finally,through the combination of theory and experiment,the practical and feasible drag reduction schemes for hub bearings and brakes are obtained respectively.(4)The pre-drive optimized drag reduction scheme and its test verification.Based on the previous article,the final optimized resistance reduction scheme for the transmission components of the target vehicle is obtained.It can be seen from the comparison test of the whole vehicle resistance torque that the resistance torques of the optimized left and right wheels are reduced by about 0.88 Nm and 0.74 Nm,respectively.It can be seen from the comparison test of the whole vehicle resistance that the inherent mechanical friction resistance of the vehicle of the optimized target vehicle is reduced by about 32.09 N.According to the vehicle taxiing distance test,the taxiing distance of the optimized target vehicle has increased by about 59.7m.Through the research of this thesis,a whole set of procedures to reduce the drag resistance of FF MPV has been set up,which provides the direction for other FF automobile to reduce the resistance of transmission system.At the same time,the theoretical analysis and experimental verification of the wheel hub bearing and the gearbox bearings have been done,which can provide reference for the follow-up study. |
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