GB964513A - Improvements in or relating to clutch operating mechanism for vehicles - Google Patents

Abstract

964,513. Fluid-pressure servomotor control systems. AUTOMOTIVE PRODUCTS CO. Ltd. Sept. 5, 1960 [Sept. 23, 1959; July 4, 1960], Nos. 29939/60 (Divided out of 964, 511) and 23357/60. Heading G3P. [Also in Division F2] A compressed air or suction servomotor for disengaging a vehicle friction clutch against the load of springs or other engaging means is so controlled by a valve that the pressure differential acting across the servomotor is substantially proportional to the movement of the clutch pedal. In one embodiment (Fig. 9, not shown) the arrangement is included in the control system shown in Fig. 1 of Specification 964,511. In the embodiment of Fig. 1 a clutch throw-out lever 14 is connected to the diaphragm of a suction servomotor 15 having a working chamber 18 connected by a conduit 23 to a chamber 37 of a control valve 24. A valve stem 38 has valve members 39, 41 slidably mounted thereon and urged by springs 42,44 respectively abutting a washer 43 on the valve stem and a fixed flange to tend to close an orifice 31 leading to a suction reservoir 25 and a passage 34 in a piston 32 fast with the valve stem. Passage 34 leads to the atmosphere via openings 35. When a clutch pedal 13, which bears on a head 33 of the valve stem, is in its released condition, a spring 45 moves the piston 32 against an abutment 46 and the orifice 31 is closed and passage 34 open so that the working chamber 18 of the servomotor is under atmospheric pressure and the clutch is engaged. On depressing the pedal the valve member 41 seats and spring 42 is progressively extended until the pressure differential across the valve member 39 unseats it and suction is applied to the servomotor. At any degree of depression of the pedal there is a corresponding extension of the spring 42, and the valve member 39 seats when the pressure differential across it balances the load so that the pressure differential in the servomotor is proportional to the pedal movement. An arrangement operating in a similar way but having a compressed air servomotor and a modified control valve is shown in Fig. 2 (not shown). In the embodiment shown in Fig. 3 the clutch pedal 13 operates a control valve 96 and a vacuum servomotor 89 operates the throw-out lever 14 by means of a hydraulic system. Both chambers of the servomotor are normally connected to a vacuum reservoir 95. Pedal 13 is connected to a piston in a chamber 77 communicating with a cylinder 79 which communicates through a conduit 81 with a chamber of a hydraulic motor 82 disengaging the clutch and through a conduit 85 with a chamber of a hydraulic motor having a piston controlling the position of a diaphragm 97 of the valve 96. On depressing the pedal 13 the valve diaphragm is moved downwardly so that a valve head 102 closes an aperture 106 in the diaphragm and a valve head 103 unseats to allow atmospheric pressure to be applied from an orifice 105 to the working chamber 94 of the servomotor. A servomotor piston 91 is thus moved and a thrust rod 92 closes a passage 88 in a piston 87 and moves this piston to increase the pressure in the clutch motor 82, to which pressure has already been applied due to movement of the pedal 13 which took up clearance at the clutch release bearing. The movement of the piston 87 increases the volume in the cylinder 79 so that the valve motor piston retracts due to the pressure differential across the diaphragm 97 and the orifice 105 tends to close. The pedal 13 must therefore be progressively depressed to increase the pressure differential and the pressure differential is substantially proportional to the pedal movement. A similar arrangement can be used having a compressed air servomotor. A modification of the arrangement replaces the hydraulic connection between the piston 87 and the throw-out lever by a mechanical connection. In the embodiment of Fig. 6 a vacuum servomotor 114 has a diaphragm 117 connected to a pull rod 118 coupled to the clutch throw-out lever 14. A lever 119 is pivoted coaxially with the throw-out lever 14 and is connected at one end to the pedal 13 by a thrust link 121, or, in a modification, by a hydraulic telemotor motor arrangement, the other end of the lever having a lostmotion connection with the rod 118. A control valve 125 is mounted on the diaphragm 117 and is actuated by the lever 119 through a thrust rod 126. When the pedal is free a valve diaphragm 128 is held by a spring in the position shown in which an aperture 134 is open and a valve head 138 seals an orifice 135 so that a working chamber 116 of the servomotor is open to the atmosphere and the clutch is engaged. Depression of the pedal 13 moves the lever 119 and thrust rod 126 to move the diaphragm until the valve member 142 closes the aperture 134 and a stop 141 on the rod 126 unseats the valve head 138 so that suction from a reservoir 137 is applied to the working chamber. The servomotor diaphragm 117 follows the movement of the thrust rod 126 tending to re-close the orifice 135 so that the pressure differential in the servomotor is proportional to the movement of the pedal. This arrangement may be modified for operation by compressed air. In the embodiment of Fig. 10 the body of a control valve 201 is mounted on the pedal 13 which is connected to the throw-out lever 14 by a link 198. Depression of a pedal pad 199 moves a valve plunger 203 and a valve head 215 closes passages in the plunger leading to the atmosphere. A valve head 213 opens an aperture 214 so that suction from a reservoir 185 is supplied to a servomotor chamber 181 to disengage the clutch. Actuation of the servomotor causes the pedal 13 to follow up the movement of the pad 199 and thus the pressure differential across the servomotor is substantially proportional to the pedal pad movement.