Patent GB-467309-A (GB)
Title: Improvements in clutch control mechanism for automobiles
Filed: 1936-09-25
Abstract: 467,309. Fluid-pressure servomotorcontrol systems. BENDIX AVIATION CORPORATION. Sept. 25, 1936, No. 26081. Convention date, Sept. 26, 1935. Addition to 449,545. [Class 135] [Also in Group XXIV] In clutch-control mechanism for a motor vehicle as described in the parent Specification, the valve means responsive to the throttle operation and to the pressure in the servomotor is provided with an adjustable stop whereby the maximum clutch load is limited. The valve means comprises a casing 30 within which is slidable a sleeve valve 66, Fig. 2, secured to a spring-loaded diaphragm 60, the left-hand side of which is open to the atmosphere while the chamber 96 at the right-hand side is connected to the servo 16, Fig. 1, by a pipe 28'. A spring- loaded valve plunger 74 slidable in the sleeve 66 carries an adjustable stop nut 108 co-operating with the end of the casing and is operated by a cam surface on a link 76, one end of which is connected by link 54 &c. to the accelerator 32 while the other end is pivoted to a lever 80 pivotally mounted on the valve casing. An adjustable stop 102 limits the anti-clockwise turning of the lever 80, and a stop 86 on the latter limits the clockwise turning of the link 76 on the lever. On release of the accelerator, the link 76, lever 80, and plunger 74 move into the position shown in Fig. 2. A space 88, which is provided by a triangular portion 90 of the plunger 74 and which is in communication with the chamber 96 through ports 68 in the sleeve 66, is thus brought into communication through ports 70 in the sleeve with a chamber 94 connected to the engine intake manifold 24 through a pipe 26. The clutch therefore disengages. At the same time, the sleeve 66, due to the suction acting on the diaphragm 60, moves to the right into the position shown. On depression of the accelerator, the plunger 74 moves to the left, putting the space 88 into communication with the atmospheric space at the left-hand side of the diaphragm 60, so as to initiate clutch engagement. The sleeve 66 follows-up the plunger 74 under the influence of the changes of pressure in the servo 16, giving a clutch engaging characteristic identical with that of the parent Specification. The stroke of the plunger 74 and thus of the servo 16 is, however, limited by the adjustable nut 108 so that complete de-energization of the servo is precluded and the maximum clutch loading is limited. During the initial depression of the accelerator, to take up lost-motion 100 in the connection between the accelerator and the throttle 34, the link 76 and lever 80 act as a single rigid lever, due to the stop 86, until the stop 102 engages the casing 30, after which the link pivots about the lever. The stop 102 is so adjusted that it contacts with the casing upon initial contact of the clutch plates. In a modified form, the plunger 74 is replaced by a second sleeve valve. A valve 154, Fig. 5, controlling communication between the chamber 94 and the pipe 26 is urged to closed position by a spring 160 and is adapted to be opened by an electromagnet 152. A switch 148, Fig. 8, in the circuit of the magnet is normally closed but is opened when the gear-shift lever 156 is in high-gear position. A switch 164 arranged in parallel with the switch 148 is normally open but is closed when the generator cut-out 162 opens. Thus the servo is rendered inoperative when the vehicle is running above a predetermined speed in high gear. In a modification, the switch 164 is closed when the brake pedal is depressed. The Specification, as open to inspection under Sect. 91, comprises also the provision of a checkvalve 112, Fig. 5, between the chamber 94 and the pipe 26. This subject-matter does not appear in the Specification as accepted.