2017 Volume 11 Issue 6 Pages JAMDSM0087
The traction drive - integrated drive generator (T-IDG®) has been developed since 1999 to replace current hydrostatic transmission drive generators mounted on Japanese military aircrafts. The T-IDG® consists of a generator and a half-toroidal traction-drive continuously variable transmission (CVT), which maintains a constant output speed of 24,000 rpm. In terms of coping with recent trends of high-power electric drive aircraft (MEA) and the need for weight reduction, a high-speed traction-drive CVT is advantageous over current hydro-static drive transmissions. The high-speed half-toroidal CVT has a fundamental issue regarding the thrust ball bearing, which must support a large loading force at a high rotational speed. The gyroscopic effect of the thrust ball bearing causes a serious slip called gyroscopic sliding at the insufficient preload and it damages the bearing. This paper describes the theoretical criteria and the design method for suppressing gyroscopic sliding. The test to validate the theory is also conducted with a prototype T-CVT up to 20,000 rpm with a peripheral speed of the traction contact of 70 m/s.