Patent GB-1367498-A (GB)
Title: Assistance device for a control especially a clutch control for auto mobiles
IPC: F16D48/02
Filed: 1971-11-11
Abstract: 1367498 Clutch control SOC ANON FRANCAISE DE FERODO 11 Nov 1971 [13 Nov 1970 19 April 1971] 52489/71 Heading F2L A servo-assisted clutch release mechanism for a motor vehicle comprises a pneumatic servo-cylinder 23 in parallel with a mechanical clutch release linkage 11 ... 17 and controlled by a valve 30 responsive to movement in the mechanical linkage. In Figs. 1 and 2 depression of a clutch pedal 10 acts through the mechanical linkage 15, a rod 20 and lever 51 to depress a plunger 49 and piston 39 of the control valve 30 against the bias of a spring 46. An extension 43 of the piston 39 depresses a valve element 35 to connect a servo pressure supply chamber 33 to a servo supply port 40B and to disconnect the latter from an exhaust duct 42 in the piston 39. As the pressure in the servomotor 23 builds up it acts additionally on the piston 39 to move the latter upwards against the bias of a spring 47 to permit the valve element 35 to return to its closed position under the action of a spring 37. The pressure supplied to the servo cylinder 23 is thus proportional to pedal depression. On release of the pedal 10 the piston 39 moves upwardly to vent the servo-cylinder 23 through the exhaust duct 42. The rod 20 connecting the mechanical control linkage to the valve 30 may be replaced by a flexible cable or a tension spring (Figs. 3 and 5, not shown). A stop (61) limits movement of the lever 51. In Figs. 6 and 7, a clutch pedal 10 which acts directly at 14 on a clutch release mechanism is assisted by a suction servomotor 23. The pedal 10 is connected by a spring 81 to a control valve 65. On depression of the pedal 10 a control element 80 of the valve 65 moves right to disconnect the servo cylinder from exhaust and to move a valve element 75 right and connect a suction chamber 73 with a chamber 74 which communicates with the servo cylinder 23. As the pressure in the servo cylinder 23 and chamber 75 drops the valve element 80 returns to the position shown. The suction in the servo cylinder is thus proportional to pedal depression. In Figs. 9 and 10 (not shown) the spring 81 and the piston 28 are connected to the pedal 10 at offset points. In Fig. 11 (not shown) the spring 81 is replaced by a blade spring connected at one end to the control valve casing and at its other end to a tie rod fast with the pedal 10 whilst an intermediate point of the blade spring acts on the valve element 80. In Fig. 12 (not shown) a stop (188) limits movement of the blade spring so that depression of the pedal beyond a predetermined point reduces the servo assistance. In Fig. 13 (not shown) the control valve is modified so that the suction acts on the control element 80 through an orifice (215) to delay return of the element 80 to its initial position. In Fig. 16 the tie rod 220 connected to the pedal 10 is also connected to a cam 221 which is pivoted on a spindle 222 fast with a slide 224. A frictional connection restricts movement of the cam 221 about its pivot 222. The cam 221 acts on the blade spring 181 to operate the control valve elements 80. On initial depression of the pedal 10 the slide 224 moves right to provide an initial servo assistance to the pedal. When the slide 224 reaches the end of its movement the cam 221 rotates about its spindle 222 to further increase servo assistance at a reduced rate. On release of the pedal 10 the slide 224 initially moves back to the position shown to provide a rapid decrease in servo assistance and thereafter the cam 221 rotates on its pivot 222 to its initial position and further reduces servo assistance at a reduced rate. In Figs. 19-22 (not shown) the cam is carried by a lever pivotable between stops. In Figs. 23 and 24 (not shown) the cam co-operates with one stop whilst the slide co-operates with another stop.