Patent GB-432600-A (GB)
Title: Improvements in and relating to power operated transmission mechanism for motor vehicles
Filed: 1934-05-04
Abstract: 432,600. Operating clutches; variable-speed gearing. GILLETT, E. H. J. C., 32, Marlborough Mansions, Cannon Hill, West End Lane, London. May 4, 1934, No. 13532. [Class 80 (ii)] A motor-vehicle clutch is operated by a power device controlled : (1) by a device responsive to engine speed, (2) by a throttle-connected device adapted to produce engagement irrespective of engine speed when the throttle opening exceeds a certain amount, and (3) a control adapted to produce disengagement independently of the other two controls. The independent control may be connected to the gear lever so that clutch disengagement is brought about during gear-changing. In the form shown, the clutch operating shaft 57, Fig. 1, carries a lever 56 engaging a servo-piston 54 operated by pressure-oil from a gear pump 21, 22, the driving shaft 23 of which is constantly rotated from the engine crankshaft. The supply of oil to the servo-cylinder 53 is controlled by valves 37, 46, 31, Fig. 2. The valve 37 is connected to the accelerator pedal. The valve 46 is operated against the action of a spring 47 by centrifugal weights 52 rotating with the shaft 23. The valve 46 is provided with a follow-up sleeve 43 connected by studs 59 to the clutch operating lever 56. The valve 31 is connected to the gear lever by the mechanism described in Specification 395,692. The pump 21, 22 draws oil from the sump 20 and supplies it through conduit 28, Fig. 8. If a gear is engaged, the valve 31 is in the position shown and the oil passes through the openings 29, 33 into the annular space 34 around the follow-up sleeve 43, whence it escapes to the sump through the ports 44, 45 in the sleeve. If the throttle is opened more than a certain amount the valve 37 is to the right as shown, so that oil also escapes from the space 34 through openings 35 and 39 to the sump, whatever the position of the valve 46. Thus no pressure can be developed in the servocylinder 53 and the clutch remains engaged. To prevent too rapid engagement of the clutch when the throttle is fully opened the passage 39 is constricted. If the throttle is partly closed, the valve 37 closes the opening 39 and the governor 51 effects the control. If the engine slows down below a certain speed, the valve 46 is moved to the right by the spring 47, and the ports 44 tend to close, thus allowing pressure to develop in the cylinder 53 so that the clutch begins to disengage, producing a follow-up of the sleeve 43 until a position is reached at which the ports 44 are partly open and a definite position of the clutch is established. If the gear-lever is operated, the valve 31 is pulled to the left, thus closing the opening 29, so that pressure is developed in the cylinder 53 and the clutch disengaged whatever the position of the other two valves. A relief port 61 is provided in the piston 54 to limit its stroke. In a modification, the arrangement described in Specification 421,894 is varied by providing a mechanical connection from the accelerator to press the main valve stem in the opening direction. Alternatively, the independentlycontrolled valve is placed on the inlet side of the speed-controlled valve disclosed in Specification 421,894 or a double independent valve capable of simultaneously opening and closing two independent relief channels may be situated between the speed-controlled and throttle-connected valves. Specification 416,663 also is referred to in the Provisional Specification.