Abstract: The double parameter shifting schedule (DPSS) of dual clutch automatic transmission (DCT) controled by vehicle speed and engine throttle opening, based on enine torque model, engine fuel model and gear ratios of DCT, is designed. In the hardware-in-loop simulation test, some unreasonable shifting phenoemnons such as frequent shifting in EUDC drive cycle and needless shifting in urgent braking condition are found. The reason of the unreasonable shifting phenoemnon is analyzed, then, the conclusion that the unreasonable shifting is mainly caused by the incorrect operation of the driver is presented, and the unreasonable shifting is hard to be avoided if the DPSS is used. To eliminate the improper shifting under certain driving conditions, an intelligent compensating shift schedule (ICSS) is devised on the basis of “sugeno” fuzzy logic. The ICSS is composed of the input parameters including throttle opening and its changing rate, output parameters including upshift and downshift compensating ratio, membership function and fuzzy control principle. The downshifting speed at a given throttle opening is obtained from multiplying the corresponding speed inferned from DPSS by the downshift compensating ration inferred from ICSS, but the upshifting speed is obtained from dividing the corresponding speed inferred from DPSS by the upshift compensating ratio inferred from ICSS. The final test results prove the ICSS can eliminate the improper shifting in drive cycle and braking condition, and the fuel economy is also improved.

Key words: Design and application, Dual clutch transmission, Intelligent shifting schedule, elliptical hinge nonlinear curve fitting rotation stiffness finite element analysis