Browse Publications Technical Papers 2018-01-1936
2018-10-30

Dynamic Stability Analysis of High-Speed Traction Drive CVT for Aircraft Power Generation 2018-01-1936

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, that is, 400Hz AC power supply. 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 torque on the half-toroidal CVT is transmitted through multiple power rollers. The equal load sharing among power rollers are typically controlled by mechanical-hydraulic feedback system, whose stability is one of the biggest issues for the high-speed traction-drive CVT. Previous studies have shown that the insufficient damping and stiffness of the mechanical hydraulic feedback system causes self-induced vibration. We found that the support stiffness of the CVT also affect the stability of the feedback system when it is driven at high speed. This paper describes the theoretical criteria to maintain the stability of the power sharing system of power rollers of the high-speed CVT. The test to validate the theory is also conducted with a prototype traction-drive CVT up to 20,000 rpm with a peripheral speed of the traction contact of 70 m/s. The test results show that the vibration is excited at high rotational speed when the CVT is supported with low stiffness of bearing support. We conclude that the high support stiffness is necessary to transmit the power stably with a high-speed traction-drive CVT.

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