Patent GB-841876-A (GB)
Title: Improvements in and relating to vacuum control devices for use with carburettors of vehicle internal combustion engines
IPC: F02D9/00
Filed: 1957-06-05
Abstract: 841,876. Carburetters; supplementary air admission devices. WILLMER, V. G. June 5, 1957 [June 8, 1956], No. 17948/57. Classes 7(2) and 7(3). A vehicle engine control device includes a chamber communicating with the carburetter and intake manifold of the engine, an air inlet to the chamber, a vacuum break valve normally closing the inlet, vacuum-responsive mearis comprising a diaphragm operatively connected to the vacuum break valve to move it, a space partly bounded by the diaphragm and subjected to the vacuum in the carburetter whereby the diaphragm will be moved to cause the vacuum break valve to be opened, a relief aperture connecting the space to atmosphere, a relief valve in the aperture and means operable by the normal driving controls of the vehicle to open the aperture and thus disable the vacuum responsive means. As shown a chamber 10 has an extension (not shown) which fits between the carburetter 13 and the intake manifold 14. Thus air which enters an upper chamber 20 by way of a gauze covered air inlet 21 can enter the chamber 10 from the chamber 20 when a valve (not shown) operated by a diaphragm (not shown) in the housing 26, is opened. The diaphragm is operated by the pressure above it in a chamber 24 and the chamber 24 is connected by a pipe 34 to the chamber 10 and thus to the intake. The pressure in the chamber is dependent upon the suction in the intake and the apparatus described below. A control tube 41 leads from the chamber 24 to a clutch-actuated air valve 42. This air valve is of a known type in which an air inlet 44 is normally maintained closed but may be opened when any degree of inward movement is imparted to a spring-loaded stem or plunger 45 by means of a pivoted lever arm 46 the latter being connected to an actuating rod 47 leading to the vehicle clutch (not shown) and adapted to be moved in the direction indicated by the arrow whenever the clutch pedal is depressed. The air inlet 51 will normally vent to atmosphere the chamber 24 but it may be closed when desired by pulling the knob 59 to cause the valve member 53 to seal the end of the tube 51. The valve member 65 is arranged so that it will be held against the end of the air inlet tube 64 when the accelerator (not shown) is released or inoperative and to be clear of the air inlet tube 64 only when the accelerator is pressed. To this end an actuating rod 66 from the accelerator is pivotally connected to an arm 67 of a lever member which has another arm 68 connected by a pivoted throttle operating rod 69 to the mixture throttle valve (not shown) of the carburetter. A control screw 70 is screwed into a lug 71 so that when the accelerator is released the screw 70 will bear against and urge the valve member 65 into closed position. When the rod 66 is moved upon depression of the accelerator the valve member 65 will immediately move to open the air inlet tube 64 but the rod 69 will move a short distance against the action of the spring 72 before its upper nut will strike the portion 74 of the member 70a to cause the rod 71a to operate the mixture throttle valve. The construction lends itself to the use of a governor device of any known type associated with the transmission of the vehicle or a wheel thereof the governor being connected by a suitable cable to the valve member 65 so that when the vehicle reaches a predetermined speed the valve member 65 will be moved to close the air inlet tube 64 even though the accelerator has been pressed.