DESIGN OF A SINGLE MODE VARIABLE BRIDGE TYPE SPLIT-POWERED CVT WITH AN INNER-SPHERICAL CONTINUOUSLY VARIABLE UNIT

摘要

One method for improving the torque capacity of the CVT is to use a split-powered CVT (SPCVT) to reduce the power transmitted into a continuously variable unit (CVU). A variable bridge SPCVT with two planetary gear units (PGUs), which are composed of a sun gear, a ring gear, and carrier and planetary gears, can minimize the power to the CVU. However, a SPCVT with a conventional CVT should possess a dual mode, which would allow the conventional CVT to be used at high speeds and an additional gear train to be used at low speeds. The inner-spherical CVU (ISCVU) with an inner and outer spherical contact mechanism developed in this study can cover the range from low to high speeds. The rated power and the overall speed ratios were 100 kW and 0.09～0.36, respectively. Power efficiency was numerically calculated to be over 90% over the speed ratio range of 0.1～0.29. The maximum shear stress at the two contact areas of the rotor pairs, the minimum life and the overall size were estimated to be 700 MPa, 276 kh and 350×350×400 mm{sup}3, respectively. This study shows that an ISCVU and a variable bridge type PGU can realize the SPCVT with a single mode for a vehicle.