Patent GB-986790-A (GB)
Title: Automatic variable-speed transmission for motor vehicles
IPC: F16H61/662
Filed: 1964-02-25
Abstract: 986,790. Variable-speed gear; friction clutches; disc brakes. PROTECTOR INVESTMENT TRUST. Feb. 25, 1964 [March 26, 1963 (2)], No. 7800/64. Headings F2C, F2D and F2E. A continuously-variable-ratio gear for motor cars &c., comprises planetary friction rollers 9, Fig. 8, of lenticular configuration, engaged between a fixed outer race 3, an input race 6 slidden axially against the bias of a spring 25 by centrifugal masses 23, and the face of a disc 8 splined for rotation with a driven shaft 2 but for axial movement along the driven shaft under the control of an output-torque-responsive cam- and-roller device 17, 18. As the planetary rollers 9 tilt, with axial movement of the input race 6 and the output disc 8, the point of contact of the curved face of each roller moves radially across the driven disc 8, to give a variable forward ratio extending from 1: 0 to 1:1. By depression of a reverse pedal 51, Fig. 9, acting through an overload-twisted coil spring 51a upon a control fork 29, a control sleeve 27, Fig. 8, can be slidden leftwards against the bias of springs 50, 32, first to release locking balls 26 and then to entrain an abutment sleeve 24 acting through the centrifugal masses 23 upon the inner race 6, which is now moved axially to so tilt the rollers 9 that their front curved faces engage an additional friction face 4c, Fig. 3, on the inner race 6. The gear then gives reverse. The torque responsive device upon the output shaft 2 comprises rollers 18, Fig. 8, journalled upon radial pins 19 and engaging helically-shaped cam slots 17 in a sleeve 12 slidable and axially rotatable upon the driven shaft and formed with splines mounting the driven disc 8. A pair of flat springs 15 connect the sleeve 12 to the driven disc 8. At very low road speeds, when overloading occurs, the springs 15 collapse, the planetary rollers 9 start to slip, the centrifugal masses 23 fly radially outwards and the transmitted torque consequently falls. The driven disc 8 may be made axially flexible by forming it with radial slots (not shown). The planetary lenticular rollers 9, Fig. 5a, are journalled upon pins 10 in a common ring carrier 11 by ball bearings having part-spherically shaped outer races to allow some degree of tilting. Friction clutches.-When the motor car is stationary with its engine idling, the planetary rollers tilt to the position shown in Fig. 3, where they are clear of the inner race 6. Accordingly, drive is not transmitted to the output shaft 2. With gradually increasing engine speed, the centrifugal masses 23 pivot radially outwards, thus sliding the inner race 6 rightwards into engagement with the inner edge of the planetary rollers 9, Fig. 1 (not shown), which begin to tilt and drive the driven disc 8. As the speed of the inner race 6 increases, the point of contact c of the curved front face of the planetary rollers 9 moves radially inwards across the driven disc to give increasing gear ratio, the point of contact being modified by the actuation of the outputtorque-responsive device 17, 19. When a sufficiently high engine speed has been achieved, the point of contact c on the front face of each planetary roller 9 moves inwards to a position radially opposite the point of contact b of the back of the roller with the inner race 6, to establish direct drive, the planetary rollers at the same time moving clear of the fixed reaction race 3, Fig. 4 (not shown), to reduce wear. Disc brakes.-When the car is stationary with the engine idling, as described above, the point of contact c, Fig. 3, between the front face of each planetary friction roller 9 and the flat face of the disc 8 fast for rotation with the output shaft 2, is opposite the point of contact a of the back of each roller 9 with the stationary reaction race 3. Accordingly, the disc 8 and the output shaft 2 are held stationary, so that a parking brake on the motor car can be dispensed with. Lubrication.-Oil is introduced into the gearing through a pipe 39, Fig. 8, some then entering holes 41 in the driven disc 8 whence it is flung centrifugally on to the planetary rollers 9. Oil leaves the gearing through a pipe 42 leading to a pump.