Patent GB-442174-A (GB)
Title: Improvements in clutch control mechanism
Filed: 1934-10-19
Abstract: 442,174. Operating clutches. BENDIX AVIATION CORPORATION, 105, West Adams Street, Chicago, U.S.A. Oct. 19, 1934, No. 29974. Convention date, Oct. 20, 1933. [Class 80 (ii)] [See also Group XXIX] In a motor-vehicle clutch, the force of the springs tending to cause engagement is opposed by fluid trapped in a container provided with a bleed valve which is spring-biassed towards closing position, the spring being opposed by two pressures, one of which is proportional to the pressure of the clutch springs while the other, which is provided by the engine, increases with increase in engine speed. The bleed valve comprises a three-part casing 42, 44, 46, Fig. 2, diaphragms 48, 50 being arranged between the members to form chambers A, B, C and D. The diaphragm 48 co-operates with a raised seat 72 on the member 46 to act as a valve controlling communication between the chamber C, which is connected through a pipe 84, Fig. 1, with the non-suction end 40 of an accelerator-controlled engine-suction servo 10, and an air outlet 100, the diaphragm 48 being urged towards the seat 72 by an adjustable spring 54. A pin 66 secured to the diaphragm 48 is adapted to contact with the diaphragm 50. The delivery side of the engine water pump 74 is connected to the chamber B and the inlet side of the pump to the chamber A, the pump being such that the pressure developed thereby is directly proportional to the engine speed. Upon release of the accelerator 34, the suction end 26 of the servo is put into communication with the engine intake manifold 30, and the clutch is disengaged. Upon initial depression of the accelerator, between which and the throttle a lost-motion connection is provided, the servo is put into communication with the atmosphere to allow the clutch springs to act. The first part of the engaging stroke is relatively rapid, due to the efflux of air from the end 40 through a slot in the piston rod, and thereafter efflux of air continues past the diaphragm 48. The spring 54 is so adjusted that when the clutch plates have contacted with a predetermined light load, with consequent reduction of pressure in the chamber C, the diaphragm seats to prevent further bleed. As the accelerator is further depressed, the engine speeds up, the pressure in chamber B increases, and the diaphragm 50 acts through the pin 66 to unseat the diaphragm 48. The clutch load is thus further increased, the pressure in chamber C decreases, and the diaphragm 48 reseats. At any instant after the clutch plates have initially contacted, the clutch loading is thus directly proportional to the engine speed. Weights 52 and 70 are secured centrally to the diaphragms 48 and 50 respectively, so that if the acceleration of the vehicle during forward movement is excessive the diaphragm 48 is seated to maintain the existing clutch loading until the acceleration decreases ; alternatively, the air outlet 100 may be controlled by a slide valve 114, Fig. 5, actuated by a pivoted weight 110, such that the valve 114 is closed when the vehicle acceleration is excessive in either forward or reverse movement. In a modification, the chamber A is open to the atmosphere and the chamber B is connected to the engine exhaust manifold. In a further modification, a single diaphragm 48 forming two chambers is employed, as shown in Fig. 7, the chamber A being connected to a Venturi device mounted in the air intake to the carburetter, while the chamber C is connected to the end 40 of the servo, as before, and the servo is controlled automatically in accordance with the engine suction instead of by the accelerator. According to the Specification as open to inspection under Sect. 91, the oil pump of the engine may be employed instead of the water pump. This subject-matter does not appear in the Specification as accepted.