Patent GB-1476852-A (GB)
Title: Electro-pneumatic device for regulating the supply of air to an internal combustion engine
IPC: F02D35/00
Filed: 1975-09-11
Abstract: 1476852 Automatic control of fuel/air mixture REGIE NATIONALE DES USINES RENAULT and AUTOMOBILES PEUGEOT 11 Sept 1975 [26 Sept 1974] 37439/75 Headings G3P and G3R [Also in Division F1] Exhaust pollution from an engine is reduced by mixing air with the mixture formed in the carburetter in a quantity which is controlled by an electronic regulator responsive to sensed exhaust gas composition and engine speed by a suction controlled valve arrangement comprising a regulator valve which controls the mixing air-flow and is itself controlled by a command pressure derived from the mark/space ratio of an electrical signal supplied by the electronic regulator to a command valve. In the arrangement shown in Fig. 1, air at atmospheric pressure Po is drawn through carburetter 3 into the engine 1 at a manifold pressure of Pa which is lower than Po. The exhaust gas composition is monitored by sensor 7 which supplies a signal to electronic regulator 8 together with a speed signal derived from ignition contact braker 13 to produce a pulse output which is used to operate valve 9. The valve arrangement 9, see Fig. 5, includes a solenoid 51 which is pulsed to change the flow-path from inlet pressure Pa on line 54 to line 55 which carries either atmospheric pressure or an intermediate pressure Pi derived within the valve 10. In an alternative arrangement the solenoid operates an on/off valve which pressurizes the changeover valve. The valve 50 causes an average command pressure Pc to be produced in line 23 by virtue of the mark/space ratio of the applied signal to solenoid 51 and this alters the position of diaphragm rod 20 in valve 10 causing the opening of slots 16 to change and thus alter the air-flow to line 25, see Fig. 2. In the valve 10 a regulator section consisting of vacuum capsule 35 and diaphragm 39 alters the opening of ports 31 so that an intermediate pressure Pi is produced such that the pressure difference Pi-Pa is proportional to Pa. In a first modification of the regulator section of the valve the vaccuum capsule may be replaced by a second diaphragm having a controlling spring, with the first diaphragm acted on by pressures Po and Pa and the second by pressures Pa and Pi, Fig. 3 (not shown). A further modification finds a single spring controlled diaphragm acted on by pressures Pa and Pi, Fig. 4 (not shown). The electronic control system essentially comprises a pulse generator driven by the contact breaker and supplying a signal which operates the valve 9 in such a way that the space 22 in valve 10 can neither completely fill nor completely empty but it is required that emptying predominates so either the mark/space ratio of the electronic signal or the size of ports in the valves are adjusted accordingly. In the arrangement described with reference to Fig. 10 (not shown) the mark/space ratio of the signal from the pulse generator is modified by the presence or absence of a signal from the exhaust gas sensor so that the added air amount is cyclically varied to give a change in mixture richness which oscillates about the required level. An electronic tachometer arrangement is provided to interrupt the supply of added air at idling and high speeds and further controls associated with the throttle pedal may be provided to stop the supply of extra air.