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Practical approach to enhance Gear Shift Quality in Automatic Transmissions
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 06, 2021 by SAE International in United States
Event: SAE WCX Digital Summit
Passenger utility vehicles like car, SUVs, MPVs are used in wide application all over the world. Luxuries are becoming essential features of product mix along with comfort and ergonomics. Customer desires best gearshift quality with emerging technologies like AT, DCT, CVT, etc. and every OEM is working hard to achieve it. It is very difficult to satisfy the customer desire because of diversities in demographics and geographic. Gear shift quality (GSQ) is very crucial touch point in overall drive feel of vehicle. GSQ consist of various parameters like shift feel, precision, comfort, Shift Noise, etc. It demands tradeoff practices among various parameters as stated. In this paper, Shift system of Automatic transmission is explained. Various design parameters of shift system is explained with practical design approach including detent profile, gearshift mechanism, cable & dampers, etc. Among various GSQ parameters, In-cabin noise (Shift Noise) during gear shifting is also one of the crucial parameter. This paper thoroughly explains inter-relation between different parameter for GSQ and its effect on shift noise and shift feel; this is explained with help of various DOEs and relation matrix. In this study various practical approaches are explained to reduce in-cabin gear shift noise and to improve shift feel. The intensity and cause analysis of different parameters with help of 8d and fish bone diagrams is explained in the later part of paper. This helped to build an interrelation matrix for elucidating the crucial and critical contributing areas, how we can optimize costs is also explained with help of interrelationship matrix. The exercise is concluded in the last part of paper by referring the interrelationship matrix to decide the sequence and priority of contributing factors, critical areas and least important factors to be deled with while reducing cabin noise.