GB1214072A - Improvements to carburetion devices for the internal combustion engines of motor vehicles - Google Patents

Abstract

1,214,072. Spray carburetters. SOC. INDUSTRIELLE DE BREVETS ET D'ETUDES. Oct.8, 1968 [Oct. 11, 1967] No.47662/68. Heading F1B. A carburetter for an internal combustion engine has means for reducing atmospheric pollution by the engine exhaust gases comprising a pneumatic system responsive only when the engine speed exceeds a predetermined value, to the negative pressure in the intake conduit downstream of its throttle member to increase the minimum opening of the throttle. The carburetter has an air intake 3 to a duct 1 containing a throttle member 2 on a pivot 12 operated by an arm 13 connected by a rod 14 to the accelerator of a vehicle in which the engine is mounted. The normal idling speed is set by a stop 15. A lever 16 is loosely mounted on the pivot 12 and carries a pin 17 which comes into contact with arm 13 to open throttle member 2 when lever 16 is moved anti-clockwise. The latter movement is effected by a pneumatic system comprising a pair of diaphragms 26, 26a attached respectively to rods 30, 30a pivoted to a lever 29 connected to lever 16 via a rod 18. The diaphragms are biased to the right by springs 27, 27a in chambers 25, 25a respectively, the latter communicating via orifices 28, 28a and pipe 19 with the suction in duct 1 when a valve 20 is opened above a predetermined engine speed, say 1300- 1400 r.p.m. Thus, when the accelerator control of the vehicle is returned to the idling position from an engine speed exceeding 1300-1400 r.p.m.the increased suction in duct 1 is transmitted through pipe 19 to chamber 25 causing diaphragm 26 to move to the left. Since chamber 25a is relatively large and orifice 28a is small there is some delay before the negative pressure in pipe 19 acts on diaphragm 26a so the latter does not immediately move. Thus the movement of diaphragm 26 and rod 30 causes lever 29 to pivot clockwise about its connection to rod 30a causing opening of the throttle member 2 to a position corresponding to an engine speed greatly in excess of 1300 r.p.m. Consequently, combustion is improved although the engine does not at this time act as a brake for the vehicle. As the negative pressure progressively builds up in chamber 25a, diaphragm 26a and rod 30a move to the left causing lever 29 to pivot anti-clockwise about its connection to rod 30 and effecting slight recloring of the throttle member 2 into a fast idling position corresponding to about 1200 r.p.m. When the engine speed has fallen to about 1300 r.p.m. valve 20 vents pipe 19 to atmosphere and throttle member 2 drops back into its normal idling position so that the engine can act as a brake for the vehicle. In the arrangement shown, the valve 20 is operated by an electromagnet 21 connected to an electronic speed sensing system A, e.g. as described in Specification 1,099, 350, but the valve may be operated by a centrifugal governor. The carburettor may be combined with additional anti-pollution devices, such as those disclosed in Specification 1,214,071.