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A new concept of an electromagnetic torque converter for hybrid electric vehicles is proposed. The electromagnetic torque converter, which is an electric system comprised of a set of double rotors and a stator, works as a high-efficiency transmission in the driving conditions of low gear ratio including a vehicle moving-off and as a starting device for an internal combustion engine. Moreover, it can be used for an electric vehicle driving as well as for a regenerative braking. In this concept, a high-efficiency drivetrain system for hybrid electric vehicles is constructed by replacing a fluid-type torque converter with the electromagnetic torque converter in the automatic transmission of a conventional vehicle. In this paper, we present the newly developed electromagnetic torque converter with a compact structure that enables mounting on a vehicle, and we evaluate its transmission efficiency by experiment.

1 In general, the engine brake performance of a vehicle with an automatic transmission (AT) is inferior to that of a vehicle with a manual transmission (MT), without manually downshifting the transmission. Especially, in commercial vehicles having great variations in load capacity, improvements in engine brake performances are significant issues for vehicles with an AT in terms of both safety and performance. For such circumstances, Aisin Seiki has succeeded in the development of a 6-speed AT for commercial vehicles with an engine control system that enables the vehicle to decelerate according to desire of drivers in various driving conditions. An outline of the development of this control system is presented below.

Recently, hybrid systems for commercial vehicles have been rapidly proliferating, and demands for a reduction in CO2 have been growing concurrently. Under this circumstance, we developed a hybrid front module containing a large-diameter, thin type motor generator tailored to the characteristics of commercial vehicles, and a front clutch mechanism capable of disconnecting the engine and the drive train from each other. One of the main features of this module is the large-diameter, thin type motor generator that adopts a rotor manufactured by a winding-laminating process for low-cost manufacture and a concentrated-winding stator using a segmented stator core. Mounted inside the large-diameter, thin type motor generator is a normally closed type multiplate wet clutch designed to disengage by hydraulic pressure supply by an electric oil pump, achieving a thin and compact structure.