GB813774A - Fluid-operated clutch control arrangement - Google Patents

Abstract

813,774. Controlling clutches. FICHTEL & SACHS A.G. March 22, 1956 [March 24, 1955], No. 8952/56. Class 80 (2). In a fluid-operated clutch control system, speed-responsive means acts on two valves such that increasing speed increases the loading on one valve and decreases the loading on the other. A motor vehicle clutch is disengageable by engine suction led to a valve 15 closed by a spring 17 and transmitted to the clutch servomotor by a duct 26, a reducing valve 18 having a nozzle bore 28 primarily controls the admission of air at atmospheric pressure. Two valves 15 and 16 are acted upon by springs 13, 14 and a beam 12 moved under the influence of an engine-driven centrifugal governor 9. At idling speeds the beam 12 moves towards the valves 15, 16 compressing the springs 13, 14 to provide the maximum closing pressure on valve 16 and minimum closing pressure, against the action of spring 17, on valve 15. The valve 15 opens to admit suction to duct 26 to hold the clutch disengaged. Increasing engine speed causes the beam 12 to reduce the pressure on springs 13, 14 and thus modify the suction to the clutch servomotor by the increased closing pressure on valve 15 and reduced closing pressure on the atmospheric inlet valve 16, to produce a gradual clutch engagement. Slowing of the engine on clutch engagement increases the loading on the springs through the governor 9 to provide smooth takeup; the reducing valve 18 preventing the full flow of atmospheric pressure under such conditions. An electromagnet 23, connected through a switch with the gear-shift mechanism, actuates a change-over valve 20 through a plunger 24 to release the clutch on gear-change. Arrangements are described in which the valve assembly is adapted to be used for positive pressure clutch disengagement and for positive or negative pressure clutch engagement.