Mechatronics for “Shift by Wire” - A Technical Challenge

Increasing demands for design freedom in modern automotive cockpits stand in contrast to the still predominant mechanical coupling of the driving mode selector to the automatic transmission. Furthermore, tendencies to enhance comfort, such as “keyless go”, are becoming ever more prevalent. A “Shift by wire” system is a viable solution fulfilling these requisites. A mechatronic module, optionally mountable to an existing transmission, incorporating the inter-functionality of actuation, sensing and control electronics will be presented. The mechatronic module must supply high torques within short switching times for the entire voltage range of the battery. Legal guidelines prescribe a redundant feature assuring that the vehicle can lock into the park position at all times. The mounting location on the transmission was decisive for the module design and choice of materials because it dictated severe temperature, vibration and sealing requirements. It will be shown how these requirements were satisfied within the extremely confined space envelope and with inherently high system power density.