Study of the Connection between E-Machine and Gearbox of a Hybrid Powertrain

As part of the development of its new powertrain consisting of two electric motors, a combustion engine and a gearbox, Renault SAS followed an original approach to achieve an assembly with an optimized, robust, and reliable link between the main electric motor and the gearbox. The running operation optimization as well as the high reliability is achieved by processing the following topics: filtration of vibrations and operating jolts; solving of tribological problems specific to splined connections, such as fretting corrosion and abrasive tooth wear; avoidance of potential seizure of elements with cyclic relative slippage under load; and eventually, control of wear and tear on the sealing and damping O-rings, which must accept oscillating translational movements at the same time as torque transfer. The aim of this article is to retrace the main steps taken to achieve the desired reliability and performance targets for this type of product. The most remarkable points of this approach are: the modelling and simulation of the behaviour of a misaligned splined connection, with respect to all degrees of freedom of the components being part of the portion of the kinematic chain; the strong links between theoretical and experimental approaches to describe the behaviour of various components such as roller bearings, O-rings, and wave washers; and the quality and richness of the digital model which allows to simulate a wide range of configurations and provide access to essential variables needed for assessing the correct design and operation of the electric motor/gearbox linkage.