Study On Economy Of The Metal-Belt Type CVT’s Automobile

With the progress of science and technology, the automobile industry develops rapidly. This has brought the stern challenge for the limited oil resource and the strict emissions regulations. The balance of automobile’s dynamic performances, fuel economy, emissions and other performance is the goal that each automobile manufacturer is always pursuing. Therefore, those manufacturers made various efforts in technology. The drivetrain is an important part of vehicle. Its transmission efficiency has a direct impact on the economic performance of vehicle. The transmission, as an intermediate link of power transmission, is the core of the drivetrain. It plays a vital role of vehicle overall performance.Compared with the original transmission equipment, the CVT technology is the frontier technology and the CVT will become a tendency for future transmission development. There are many different types of CVT, and the metal-belt type CVT is currently the most widely used at present.This paper has carried on the analysis to the structure principle and torque transfer mechanism of the metal-belt type CVT at first, and established the mathematical model of pulley clamping force, then analyzed the influence of the ratio change rate to vehicle acceleration performance. This laid the theoretical foundation for analyzing comprehensive performance of the vehicle. Matching engine and transmission system analysis is the basis to analyze vehicle economic performance. Therefore, this paper established the steady state output torque model, fuel consumption model, universal characteristic curve and the transmission system power and mathematical model of engine. It studied on the engine and transmission matching in depth for achieving optimal match between engine and CVT. In the same working environment (engine, drivetrain, vehicle, etc.) for 4-AT and CVT, constant velocity and equal acceleration 100 km fuel consumption of 4-AT and the metal-belt type CVT auto were established model and simulated by MATLAB /Simulink simulation technology, and the acceleration influence to economy of CVT was researched in depth. According to the comparison of simulation results, the paper found that, the constant velocity 100 km fuel consumption of CVT’s auto is lower 4.0%～6.0% than 4-AT at 20km/h ~ 50 km/h, the constant velocity 100 km fuel consumption of CVT’s auto is lower 7.5% than 4-AT at 80 km/h and lower 14.0% at 100km/h. In acceleration conditions, higher speed, 100 km fuel consumption of CVT auto is lower than 4-AT auto and The greater acceleration increased the higher the reduced amount became. The results showed that the higher vehicle speed, the smaller100 km fuel consumption for metal-belt type CVT auto than the 4- AT, the better the economy. Using CVT technology had notable effects in improving economy of vehicle.