Power transmission system for vehicle

A power transmission system for a vehicle for transmitting engine output power to driving wheels of the vehicle comprising a first power transmission path having a forward-reverse shift mechanism, a reduction gear and a torque converter upstream of said reduction gear, said reduction gear including a planetary gear mechanism, a second power transmission path having an infinitely variable gear, and a path switching means which switches the power transmission path between the first and second power transmission paths according to the running condition of the vehicle;

• wherein said infinitely variable gear is formed of a toroidal speed change mechanism comprising an output disk fixed to an output shaft of the power transmission system ,an input disk which can be displaced in the axial direction of the output shaft and a roller which is in contact with both the input and output disks to rotate about an axis in response to rotation of the input disk and transmit rotation of the input disk to the output disk, the transmission ratio of the toroidal speed change mechanism being changed by changing the inclination of the axis about which the roller rotates;
• and said second power transmission path has a bypass shaft which extends in parallel to the axis of the planetary gear mechanism, one end of the bypass shaft being connected to an input element to the torque convertor by way of a first gear train and the other end of the bypass shaft being connected to the input disk of the toroidal speed change mechanism by way of a second gear train.

A power transmission system for a vehicle for transmitting engine output power to driving wheels of the vehicle comprising a first power transmission path having a forward-reverse shift mechanism, a reduction gear and a torque converter upstream of said reduction gear, said reduction gear including a planetary gear mechanism, a second power transmission path having an infinitely variable gear, and a path switching means which switches the power transmission path between the first and second power transmission paths according to the running condition of the vehicle;

• wherein said infinitely variable gear is formed of a toroidal speed change mechanisms arranged side-by-side in the axial direction and including an output disk fixed to an output shaft of the power transmission system, an input disk which can be displaced in the axial direction of the output shaft and a roller which is in contact with both the input and output disks to rotate about an axis in response to rotation of the input disk and transmit rotation of the input disk to the output disk, the transmission ratio of the toroidal speed change mechanism being changed by changing the inclination of the axis about which the roller rotates;
• and said second power transmission path has a bypass shaft which extends in parallel to the axis of the planetary gear mechanism, one end of the bypass shaft being connected to an input element to the torque convertor by way of a first gear train and the other end of the bypass shaft being connected to the input disk of the toroidal speed change mechanism by way of a second gear train.