Research Based On Engine Characteristic Surface On Shift Strategy Of Transmission

Transmission system is an important part of the vehicle，either a manual or anautomatic gearbox， the shifting operation play a very important role in dynamicperformance and fuel economic performance of the car. A reasonable shift strategy oftransmission can help the car to make the full use of the dynamics of the engine andimprove the fuel economic performance，it is the core part of the transmission. Thus，theresearch of shift strategy is becoming one of research focus in the field of transmission athome and abroad.This thesis is funded by Chongqing Municipal Education Commission (ProjectNumber：KJ080619). Based on the engine characteristics and its surface，this article studyon theory related to shift strategy of manual transmission and DCT，using Matlab softwareto calculate and analyze the issue，and finally come to the conclusion.The main researchcontents of this paper include：1、The torque characteristics of engine is analysed and the limitations of the analysisof engine characteristic in current automobile theory is pointed out. The test data of engineis calculated and analysed，on the basis of this，the external characteristic curve of engineand other related graph in teaching material has been corrected，so the graph is more easyto understand and complete. On the platform of software，the models of engine torque，engine power and other characteristic parameter of engine are established by usingInterpolation method. Also，the mathematic model of engine is built up based on MultipleLinear Regression method，which lays foundation for follow-up research.2、Some characteristic surface of engine are drew by using of drawing software，onthe basis of these figures，operation performace of engine under different kinds of workingcondition is studied. Then，all the torque and power working line which match to thetransmission is obtained and analyzed on the characteristic surface，especially the constantpower line.3、A new method to calculate the engine′s relative fuel consumption is proposed andthe fuel consumption surface has been drawn. Based on the relationship among powerline，fuel consumption line and gear line，the minimum value of fuel consumption andmaximum value of power is found in mathematic theory. According to the minimum fuelconsumption curve and gear line，the economic working area of engine and better gear lineis analyzed，then reasonable shift time is confirmed as well as the related engine speed. At a certain distance，the fuel consumption of all gear is compared and analyzed，then the bestgear line in theory is obtained. From the conclusion in hand，the transmission used in thispaper is optimized.4、Shifting characteristic and shift strategy of automatic transmission is studied，andshift-delay which effects the shift quality of DCT is discussed and identified. Combinedwith the fuel consumption surface，a new method to formulate economic shift rule isintroduced，and this kind of method is simple and easy to read in comparison with currentmethod. Finally，the dynamic，economic and integrate mode shift performance rule basedon two-parameter is obtained.