GB877590A - A new or improved device for controlling operation of friction clutches - Google Patents

Abstract

877,590. Gearing for stopping and starting machinery. ZAHNRADFABRIK FRIEDRICHSHAFEN A.G. Feb. 13, 1959 [Feb. 15, 1958], No. 5152/59. Class 80 (2). To obtain cushioned re-engagement of a friction clutch 6 on a motor car, disengaged against the bias of a spring 7 when fluid under pressure is admitted through a port 11 to act upon the piston 2 of a servomotor, a floating piston 8 is provided between the port and the servomotor piston, the floating piston incorporating a one-way valve 9 which freely admits pressure fluid to act on the servomotor piston 2 for clutch disengagement and the floating piston being biased rightwards against a stop 13 by a spring 10. When the pressure of the fluid supplied at the port 11 is allowed to fall for clutch re-engagement, the clutch-engaging spring 7 slides the servomotor piston 2 leftwards and the fluid trapped by the one-way valve 9 in a space 14 between the servomotor piston and the floating piston 8 slides the latter leftwards against the bias of its spring 10. When initial engagement of the clutch 6 has been achieved, the bias of the clutch spring 7 equals the bias of the floating piston spring 10. Completion of the engagement of the clutch is then obtained by the slow seeping of fluid from the space 14 adjacent the servomotor piston 2 through a restricted by-pass passage to the inlet port 11. In the form shown, the restricted bypass passage comprises a pipe 17 the flow through which is adjusted by a needle valve 18 under the control of a vacuum servo 21 connected to the inlet manifold of the car engine by a pipe 22, adjustment of the accelerator pedal position varying the inlet manifold depression and hence the position of the valve 18 to control the speed of clutch re-engagement. In a modification, Fig. 1 (not shown), the by-pass pipe 17 is replaced by a groove in the piston 8 to one side of the one-way valve 9, this groove allowing a slow bleed of the operating fluid. The clutch may be associated with a change-speed gear in which the ratios are established by servo means actuated either manually or in dependence on the speed or torque of the car engine.