Detent Bearings Represent an Integral Solution for Double Clutch Transmissions Without Affecting the Design Envelope
Today, state-of-the-art double clutch transmissions attract a high level of attention worldwide and increasingly lead the automotive industry to new and efficient design envelope solutions. Often there is simply insufficient space to apply the locking contours to the gearshift forks and install the detent pins in the transmission housing. This is why Schaeffler offers an integral solution for the bearing support of gearshift elements without affecting the design envelope.
“Schaeffler’s new detent bearing offers an alternative solution for locking gearshift forks in situations where the available design space and using conventional detent pins and locking contours is difficult. The detent bearing complements the Schaeffler product portfolio and allows customers to be more flexible when defining transmission specifications,” explains Stanislav Massini, Director of Advance Development and Mechatronics at the Shift Systems Product Line at Schaeffler. The new combination comprising a locking function and a bearing for rotary and linear motion (RLF) provides an interesting alternative for designers, as detent bearings can be integrated into both the outer and center walls of transmissions. Balls used as rolling elements are guided in the stationary cage and ensure a low level of friction in the bearing support. The thin-walled, deep-drawn cup serves as a raceway for the rolling elements at the same time. The integrated spring functions as the detent pin and locks the shifting movement into place by means of the contours on both sides of the shift rod. The spring is preloaded in order to generate a specific retention force that can be adapted to suit requirements.
Even after 4 million load cycles, which equate to more than double the operating life of a gearshift fork, no wear of any kind is visible on the component. The detent bearing continues to function without any problems. The hysteresis characteristics of the new detent bearing correspond approximately to those of a conventional solution – e.g. a rolling bearing support, plain bearing ball detent pin, and locking contour – thus making it a significantly better solution than designs that use plain bearings.
The level of integration can be further increased by implementing a sensor in the detent bearing if the gear position of the gearshift fork has also to be detected and the shift travel measured. Measurement takes place in the bearing itself, resulting in high linearity and measurement accuracy. The integrated connector can be connected both inside and outside of the transmission. This sensor bearing is particularly suited to use in automated manual transmissions such as DCTs and ASGs. The sensor bearing is currently being tested and shows excellent results.