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Synchroniser modeling with application specific to the dual clutch transmission

Abstract

The synchromesh type synchroniser has been introduced to dual clutch transmission applications for gear selection prior to shifting. Historical research into this type of mechanism has targeted the application to manual transmission systems only. Such work targets the phenomena associated with driver feel such as shift effort and ¿double bump¿. Now automated, the control of the synchroniser is less concerned with such aspects of the actuation, focus not trends towards repeatability of the process as well as speed of engagement. The actuation of this type of mechanism relies on the balancing of torques derived from engagement chamfers, the cone clutch and losses experienced in the transmission. These torques affect the displacement of sleeve, asynchronisation of the target gear, as well as the unblocking of synchroniser ring and indexing of the gear to the locked position. Thus a simplified model of the synchroniser mechanism and associated gear is developed for the purpose of simulating its operation in a dual clutch transmission. Unlike similar simulations this model targets the actuation of the mechanism using input forces from the controller, rather than using the control of sleeve displacement to determine maximum forces experience by the driver. To assess how operating characteristics have varied the mechanism has been modelled in the Matlab® environment. This paper presents the techniques used to model the mechanism, including the governing principles of synchroniser actuation and drag torque. Simulation results demonstrate that the primary variation in the mechanism is through the indexing chamfers. Additionally the influence of temperature variation is demonstrated for a fifth gear upshift, and the detrimental effects of cold starts demonstrated

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