Patent GB-455792-A (GB)
Title: Improvements in clutch control mechanism
IPC: B60K23/02
Filed: 1935-05-10
Abstract: 455,792. Operating clutches; fluid - pressure servomotor - control systems. BREWER, C. A., Noroton Heights, Connecticut, U.S.A. May 10, 1935, No. 13793. Convention date, May 11, 1934. [Class 80 (ii)] [See also Group XXIX] In a fluid - pressure servomotor whereby the clutch of a motor-vehicle is disengaged upon manual actuation of a control member, and on release of the latter the engaging movement is retarded or checked as the clutch parts approach complete engagement, valve means are adapted to be so actuated as to render the retarding or checking action ineffective, by a partial movement of the control member from its normal resting position in the same direction as that necessary to produce disengagement of the clutch. An engine-suction servomotor 14, Fig. 1, is controlled by a pair of connected valves 29 and 30, Fig. 2, slidable in a passage 24 which communicates with the interior of the servo through a passage 23, the valve 29 controlling a passage 27 connected by a pipe 22 to the engine intake manifold 21 while the valve 30 controls an air passage 33<a> in a sleeve 33 threaded in the passage 24. The valves are connected through oppositely-acting springs 35, 36 to a barrel 34 slidable in the sleeve 33 and having a flange 37 coacting with the end of the sleeve to form a valve controlling communication between the passage 33<a> and the atmosphere. The barrel is connected to a rod 42, which is normally urged to the left, so as to close valves 29 and 37 and open valve 30, by a spring 44 and is adapted to be moved to the right by foot depression of a rod 46 which is normally urged upwards by a spring 49 and which has a tapered end coacting with the end of rod 42. A cylindrical cam 53, adjustably threaded on a rod 54 moving with the servo piston 15, coacts with one end of a lever 51, the other end of which coacts with a spring-pressed valve plunger 55 which controls communication between a passage 50, leading to the passage 33<a>, and ports 50<a>, 58 open to the atmosphere. Passage 50 is in communication with atmosphere through an adjustable bleed valve 59. The rod 16 of the piston 15 carries a cross-pin 18 engaging the bifurcated ends of the clutch lever 11. On depressing rod 46, valves 29 and 37 are opened while valve 30 is closed, and suction is thus applied to the servo, causing clutch disengagement. On releasing rod 46, valves 29 and 37 close and valve 30 opens. The servo is thus opened to atmosphere through passages 33<a>, 50, 50<a> and 58, and the clutch plates move rapidly towards engagement. Just prior to the point of initial engagement, cam 53 operates through lever 51 to close valve 55, and thereafter the influx of air is restricted to that past the bleed valve 59, and the engaging movement is thus retarded. Towards the end of the movement, valve 55 again opens and the final part of the movement is rapid. If the rod 46 is, after it has been released to close valve 29, slightly depressed so as to open valve 37 while valve 29 is maintained closed by the suction in passage 27, the second stage of the engaging movement is accelerated by the influx of air past valve 37. On the other hand, if rod 46 is moved to such a position that both valves 29 and 30 are open, the clutch is maintained in a partially engaged position. If the valve 59 is closed, then, when valve 55 closes, the piston 15 is arrested, and, as the pressure in passage 27 rises above that in the servo, upon depression of the accelerator, valve 29 opens and engagement proceeds at a rate varying with the manifold pressure and thus with the rate of depression of the accelerator. In addition to being actuated by the rod 46, the barrel 34 may be connected to the armature 69 of an electromagnet 68 controlled by a switch which may be on the gear lever, or be operated by the accelerator. Alternatively, the switch may be centrifugally controlled so as to cause clutch disengagement when the speed of the vehicle exceeds a predetermined maximum. The clutch may be disengaged manually by over-depression of rod 46, the head 47 of the rod then acting through a loose sleeve 61 and a pivoted arm 65 on the pin 18. In a modification, the rod 16 is connected to the usual clutch pedal by a flexible cable. In another modification, the rod 16 is connected to the clutch pedal by a rigid rod ; thus, after disengagement of the clutch by manual depression of the pedal, the engaging movement is retarded at the point of initial contact by the action of the valve 55 ; a non-return valve is, in this form, incorporated in the piston.