GB940870A - Improvements in and relating to infinitely variable gears - Google Patents

Abstract

940,870. Expanding wheel gear; change speed control; variable-speed friction gear. W. REIMERS. Dec. 11, 1959 [Dec. 12, 1958], No. 42146/59. Heading F2D. In a continuously variable speed gear having driving and driven shafts each carrying at least one friction drive conical member axially slidable for ratio variation, traction pressure loading is provided on at least one of the shafts by cam means comprising balls 13 between opposing bidirectional helical surfaces 11, 15 respectively on an axially slidable conical member and a sleeve 17 which is slidably mounted on, for rotation with, the said one shaft, normally abuts a stop 23, is axially moved, on torque reversal, by a compression spring 19 to maintain contact between the balls and the helical surfaces, and, to prevent impact with the stop 23 and maintain axial pressure on the slidable conical member on return of the sleeve against the spring, forms a one-way (sleeve return) throttled piston 27 of a fluid dashpot cylinder rotating with said shaft. The gear may comprise belts or chains between expanding conical pulleys, or cones arranged at right angles to each other and in frictional contact either directly or indirectly through friction elements. The expanding conical pulley variable speed gear, particularly for motor vehicles, shown in Fig. 1, is a modification of that shown in Fig. 3 of Specification 934,798, wherein a transmission belt or chain 53 between V-pulleys 3, 4 and 5, 6 is tensioned by pulley width adjustment, and one half of each pulley is axially slidable and acted on by the cam means. To maintain, and vary at will, the gear ratio, a follow-up servo means comprising a hydraulic servo chamber defined by an axially fixed part, such as 25 and an axially slidable pulley half, such as 3, is provided for each pulley and is energized through a valve 40 jointly controlled through a floating lever 49 by the axial position of one of the axially slidable pulley halves and hand, screw, or servooperated means 52. The axial thrust provided by the cam means depends not only on the transmitted torque but, due to the helical surfaces being of changing pitch, also on the gear ratio set. On each shaft the dashpot cylinder is provided by the chamber of the servo means which on torque reversal supplements the damping means in maintaining axial pressure on the slidable pulley halves on return of the sleeve 17. The dashpot piston 27 slides within the axially fixed part 25 which may form the servo cylinder (Fig. 2, not shown), or, as shown, the servo piston. The dashpot piston may comprise throttling apertures 59 and a one-way valve means comprising an axially spring- loaded piston ring controlling radial ports in a piston flange (Fig. 5, not shown), or, as shown, a spring-loaded plate 57 controlling ports 55; or, for gradually increasing damping action, the axially fixed part 25 may have fixed thereto axially projecting tapered throttling pins entering apertures in the piston or in a spring- loaded valve plate (Fig. 8, not shown). In Fig. 11 (not shown) wherein two friction cones arranged at right angles are in direct engagement with each other, one cone is axially shifted, for ratio change, by a threaded spindle, and the other cone is provided with the cam and damping means described above.