Patent ID: 6659901
Filing Date: 2003-12-09
Classification: F16H,Y10T

Abstract:
An infinite speed ratio continuously variable transmission for a vehicle, comprising:a continuously variable transmission which can vary speed ratio continuously and has a geared neutral point which is a speed ratio making a unit output shaft stationary, a fixed speed ratio transmission, a unit input shaft which connects to input side of the continuously variable transmission and the fixed speed ratio transmission, said unit output shaft which connects to output side of the continuously variable transmission and the fixed speed ratio transmission via a planetary gear set, a first clutch device interposed between the fixed speed ratio transmission and the planetary gear set, which sets a power recirculation mode, a second clutch device interposed between the continuously variable transmission and the unit output shaft, which sets a direct mode, a clutch control unit which controls the power recirculation mode and the direct mode by selectively engaging the first clutch device and the second clutch device, a switch which commands a forward running of the vehicle, and a sensor which detects the speed ratio of the continuously variable transmission or an overall speed ratio of the infinite speed ratio continuously variable transmission, wherein at least one of the first clutch device and the second clutch device is provided with a one way clutch, a first clutch interposed in series to the one way clutch and a second clutch which is provided in parallel to the one way clutch, the first clutch and the one way clutch being arranged to cooperate to transmit torque in only one direction, the second clutch functioning to transmit torque in both directions, and the clutch control unit permits engaging only one of the first clutch device and the second clutch device when both the first clutch device and the second clutch device can transmit torque in both directions, and arranged to engage the first clutch at all times when the forward running of the vehicle is specified and to prohibit the engaging of the second clutch when the speed ratio of the continuously variable transmission coincides with the geared neutral point.