GB788483A - Improvements in and relating to control devices for electro-magnetic clutches for motor vehicles - Google Patents

Abstract

788,483. Operating clutches. SOC. ANON. FRANCAISE DU FERODO. Jan. 11, 1956 [Feb. 8, 1955], No. 1028/56. Class 80 (2). An electromagnetic clutch 12 on a motor-vehicle, energized by the usual speed-responsive generator 13 for automatic idle declutch, together with clutch release by a gearshift lever switch 14, has its torque capacity varied by insertion of resistors 13 under control of engine intake manifold depression taken at a point 41 immediately upstream of the usual engine throttle valve 10, to cause clutch pressure to follow accelerator movement at whatever rate. For ranging clutch pressure in accordance with steady torque, the resistors 13 are also varied in accordance with intake manifold depression at a point 33 well downstream of the throttle 10, or with engine exhaust manifold pressure. Pressure at the point 33 acts through a valve 26 on a spring-loaded piston 18 actuating a resistor-control arm 17, the valve 26 being controlled by the pressure-point 41 (which may be the usual tapping-point for engine ignition timing control), the valve 26 being raised when depression at 41 exceeds 0.20 to 0.33 of the maximum manifold depression. In operation, under steady drive conditions with depression at 41 below that necessary to raise the valve 26, the latter remains in its lower position shown, and manifold depression 33 acts directly on the resistor piston 18 through the valve groove 27 to insert resistors 16 into the clutch circuit at high depression (low torque) and cut them out at low depression (high torque), with intermediate action as appropriate. Under steady conditions with depression at 41 above the stated value, the valve 26 is held in its raised position and the resistor piston 18 is exhausted through either one of two valve grooves 28, 29 having graduated restrictor vents 36, 37. The resistors 16 are cut out, for maximum clutch energization. Under engine brake conditions with the throttle closed, pressure at 41 is atmospheric, so that the valve 26 remains depressed and the high depression at 33 acts on the piston 18 to insert all resistors 16 for reduced clutch energization. Under starting conditions, if the throttle 10 is opened slowly the valve piston 26 is raised, exhausting the resistor piston 18 first through the groove 28 and smaller vent 36, so that the resistors 16 are cut out slowly. If the throttle is opened rapidly, the valve piston 26 is raised to its highest position, exhausting the resistor piston 18 through its lowest groove 29 and larger vent 37 for more rapid cutting out of the clutch resistors 16. A capacity chamber 22 and one-way restrictors 31, 32 of differing sizes retard flow to and from the resistor piston 18. Dashpots may be provided or the cylinder of the resistor piston 18 may be sealed at its outer end except for a leakage path around the piston rod.