Clutches in automatic transmissions, as an important part of the hardware, represent a key component with respect to further increases and optimization of the degree of efficiency. By use of separating springs for an active separation of the lamellar plates, the drag torque losses, resulting from the relative revolutions of outer and inner lamellar discs, can be reduced significantly. The typical mechanisms for drag torque losses and their shares with respect to the differential speeds in automatic transmissions and dual clutch transmissions are explained. The potential for optimization resulting from the use of separating springs of different configurations is evaluated. To quantify these statements, the NEDC driving cycle is used as a basis. A newly developed calculation tool is presented, that allows to specify individual vehicle data in addition to the NE DC-related parameters. For automatic transmissions, the speed ratios are clearly defined by the interconnection of clutches and brakes in each shift pattern. In DCTs, the differences in speeds are due to the pre-select strategy of the gears. The parameterization of the calculation tool can be individually set to the pre-selection strategy and the expected drag torque losses can be determined. The necessary function of the drag losses at certain relative revolutions can be specified in the calculation tool. In order to do so, measurement results, that were performed on a multiplate clutch test bench, are presented by varying different separating spring parameters. By use of a basic set of parameters for an automatic transmission and a dual-clutch transmission, the influence of these spring parameters on the drag loss reduction and ultimately on the efficiency and reduction of CO2-emissions in the NEDC cycle are predicted.


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    Title :

    Drag torque reduction by separating springs in open AT-clutches and their influence on efficiency and CO2-emission


    Contributors:


    Publication date :

    2013


    Size :

    14 Seiten, 10 Bilder, 3 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English





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