Patent GB-621015-A (GB)
Title: Clutch control mechanism
IPC: B60K23/02
Filed: 1943-08-12
Abstract: 621,015. Operating clutches. BENDIX AVIATION CORPORATION. Aug. 12, 1943, No. 13050. Convention date, Sept. 23, 1942. [Class 80 (ii)] [Also in Group XXXVII] A diaphragm-motor 12, operating a frictionclutch release-lever 16 on a vehicle, is suction energised through a three-way solenoid-valve 71 under control of switches ; one 86 of which is closed by release of the accelerator-pedal 160 ; and another 302, (not described), in series therewith, which is closed by initial movement of a steering-column-mounted manual change-speed shift-lever 304, the switch 302 be reopened when manual operating-pressure is removed from the shift-lever at the completion of a shift. The clutch-release lever 16 can also be operated independently by the usual manual clutch pedal 20, which is unaffected by power operation of. the clutch, and operates a third switch 84 in series with the others, which is opened to break the power-circuit when the clutch-pedal 20 is depressed manually, to avoid the sudden release of pedalresistance in the case of possible application of power-release during a manual clutch disengagement. In parallel with the shift-lever switch 302 is a fourth switch 88, governor-operated so as to open above a predetermined vehicle-speed (13 m.p.h.). Thus below the predetermined speed, accelerator-release alone completes a clutch-disengaging circuit through the. accelerator-switch 86 and governor-switch 88, whilst above that speed, accelerator-release alone is ineffective for clutch-disengagment, for which purpose it must be accompanied by movement of the shift-lever 304, which completes the circuit through its switch 302. Clutch re-engagement is in two stages, permitting rapid initial movement to the contact position, followed by engagement at a slow rate controlled by an acceleratoroperated second-stage bleed-valve. The entire circuit is broken by the engine ignition-switch 83, and the friction-clutch is preceded by a fluidclutch, not shown. The clutch-motor 12 comprises a diaphragm, secured to a clutch-operating rod 10, and having its right side permanently vented and its left side controlled by a solenoid 71, energisation of which raises a spring-loaded valve 76, Figs. 4 and 5, to communicate the diaphragm working-chamber, through passages 210, 208, 206, 312 and 318, with the engine intake-manifold for clutch disengagement. Deenergising the solenoid 71, for clutch-engagement, causes a spring 178 to move the valve 76 onto its lower seat, as shown, to cut off the suction and vent the diaphragm working-chamber through passages 204, 200, a first-stage bleed-valve 32 (now open), and the permanently vented right chamber of a diaphragm 56 which carries the bleed-valve 32. The left chamber of the bleed-valve diaphragm 56 communicates through a pipe 308 with the working chamber of the clutchmotor 12, so that the bleed-valve 32 is initially held open by the depression in the said chamber, and remains open during the initial rapid engaging movement of the clutchdiaphragm, which tends to maintain the depression until the clutch-plates contact at the cushion-point, whereupon the clutch-diaphragm movement ceases and the depression rapidly reduces, permitting an adjustable spring 62 to close the first-stage bleed-valve 32. Further engagement of the clutch is then controlled through a conduit 198 leading to a second-stage bleed-valve 146, Fig. 6, the degree of opening of which, and so the rate of clutchengagement, depends on the position of the accelerator pedal 160, so that the clutch-plate loading is proportional to throttle . opening. This second-stage bleed-valve 146 is combined with the accelerator-operated switch 86, Figs. 1 and 6, the movable switch-contact 100 and valve 146 pivoting on spindles 98, 138 respectively, and both being operated against spring-resistance by spaced flats 152 on an operating-spindle 150, linked to the accelerator-pedal 160. The flats are circumferentially spaced so that valve-opening occurs after switch-closure, and, to ensure eventual complete clutch-engagement if the accelerator-pedal is not depressed far enough to open the second-stage bleed valve 146, the conduit 308, Fig. 5, leading to the clutch-diaphragm working-chamber, has a fixed bleed-opening 306. The fluid-coupling prevents shock on such an engagement. The governor-operated switch 88, detailed in Figs. 8 to 10, comprises centrifugal masses 240, pivoted on a shaft 218, driven by the vehicle propeller-shaft, and operating a sleeve 232, which, with speed-increase, pivots a plate 286 upwardly about a fixed fulcrum 290, to cause the centre-line of a spring 278, connecting the plate 286 to a U-shaped flat contact-plate 260, to move about the central-line of the contact-plate, thereby causing the latter to rock on fixed fulcrumtongues 272, 274, to depress a contact 263, on the contact-plate 260, away from a fixed contact 262, thus opening the switch. Due to static-friction, snap-closure of the contacts 262, 263 occurs at a lower speed (10 m.p.h.) than their opening speed (13 m.p.h.). Setting speed adjustment is provided by a wax-covered screw 296, forming an abutment for the loading-spring 294 of the plate 286. A felt pad 252 filters air drawn into the unit by rotation of the masses 240. The Specification as open to inspection under Sect. 91 states also that the selector-lever switch 302 may be omitted where the change-speed gear is provided with governor-controlled accelerator kick down shift, with accompanying ignition disablement, which renders coincidental clutch operation unnecessary. This subject-matter does not appear in the Specification as accepted.