Patent GB-1528515-A (GB)
Title: Internal combustion engines and methods of operation
IPC: F02D41/24
Filed: 1976-02-16
Abstract: 1528515 Automatic control of fuel supply NIPPON SOKEN Inc 16 Feb 1976 [10 March 1975 19 March 1975 28 June 1975] 5989/76 Heading G3N [Also in Division F1] The combustion chambers of a reciprocating or rotating piston I.C. engine are all operated with a charge having an overall air-fuel ratio above 16, eg 18, at low load and at higher loads at least some of the sequentially occurring combustions in the chambers operate with a stoichiometric or richer overall charge, eg an overall air-fuel ratio of 13. The fuel may be supplied to the air intake passages or direct to the combustion chambers via electromagnetically operated injectors or supplied by a carburetter. Exhaust gas may be recirculated to the combustion chambers operating on the richer charge and the recirculation may be terminated at full load. The spark ignition timing may be retarded in the combustion chambers burning the richer charge. The timing and duration of injector operation is controlled by an electronic control circuit receiving signals from an air intake flow detector, a generator providing signals at the beginning of the suction actions in the engine chambers and an intake manifold pressure responsive device. The carburetter is controlled by an electronic control circuit responsive to engine temperature, speed and intake manifold pressure. The engine has a  thermal or oxidizing catalytic exhaust gas reactor. First embodiment Fig. 4 and Figs. 3, 5, 7 and 8 (not shown). The engine has four cylinders 3 with injection by respective injectors 41 into the intake passages 4 to provide a richer mixture in the pre-combustion chambers 12 than the main combustion chambers 7. Exhaust gas recirculation may be effected to two of the cylinders via passages 51, 52, 53. Below a predetermined manifold pressure e.g. 660 mm Hg, a lean overall mixture is provided in all the cylinders and above the predetermined pressure the injectors of two cylinders provide an overall rich mixture in the associated cylinders, the ignition in these cylinders is retarded and a valve (55) opens to permit exhaust gas recirculation to these cylinders. Second embodiment Figs. 14 to 16 (not shown). Each engine cylinder is fed, above the predetermined manifold pressure, in alternate cycles with overall rich and lean mixture by operation of the injectors. The exhaust recirculation is controlled by respective intake manifold electromagnetic valves (51A). Third embodiment Figs. 19A and 19B. The engine of the second embodiment has an electronic control circuit receiving a continuous manifold pressure input. In all the cylinders rich overall mixture combustion occurs in one cycle of each eight successive engine cycles at the predetermined manifold pressure and the number of rich combustion cycles increases progressively to eight at full load, e.g. above 730 mm Hg. Exhaust gas recirculation is terminated at full load. Fourth embodiment Fig. 23 and Figs. 22 and 24 (not shown). All the cylinders are supplied by a common lean mixture carburetter barrel 61 and pairs of cylinders by respective rich barrels 62, 63 via cylinder head passages 33. The fuel systems of the barrels 62, 63 include respective additional jets 83, 83A which are opened to provide overall rich combustion when the jet valves are operated by respective pistons subject to manifold pressure under the control of the control circuit 88. The valves are operated above a predetermined manifold pressure difference from the atmospheric  pressure and a cooling water temperature of 20‹C, one when the engine speed exceeds 1000 rpm and both above 3000 rpm. Above 3000 rpm no exhaust gas recirculation takes place. In a modification of the fourth embodiment Fig. 25 (not shown), two lean mixture manifolds (20A-1, 20A-2) of respective cylinder pairs are fed by a lean mixture carburetter barrel and a rich mixture carburetter barrel is connected to a rich mixture manifold (20A-3) of all the cylinders. One or both pairs of cylinders are supplied with an enriched lean mixture to provide an overall rich mixture. Fifth embodiment Figs. 26 and 27 (not shown). The pairs of engine cylinders are fed by respective carburetter barrels (61A, 62A) which both provide an overall lean mixture, or one lean and the other rich or both rich by the operation of fuel enrichment devices (80, 80A) in the main carburetter fuel systems. The enrichment devices are controlled by the control circuit (88) of the fourth embodiment. Sixth embodiment Figs. 28A to 28D (not shown). Lean and rich carburetter barrels (61 B, 62B) are connected to all the cylinders through respective manifolds (20B-1, 20B-2) and air passages (63B-1, 63B-2) are connected to respective manifolds (20B-3, 20B-4) communicating with portions of the lean mixture manifold leading to respective pairs of cylinders. The air passages are controlled by respective throttle valves (90, 90A) which are closed by solenoids (94) to provide an overall rich combustion mixture in one or both cylinder pairs. Seventh embodiment Figs. 29 to 31 (not shown). Side-by-side rotors 806 define respective working chambers 809, 810, 811 and fuel is injected by injectors (841) into the chambers to provide stratification in the chambers with the richer mixture at the leading end. The duration of injection is controlled to provide a rich overall mixture in the chambers defined by one rotor or both rotors in response to closing of one or two manifold pressure switches. Eighth embodiment Figs. 34 and 35 and Fig. 33 (not shown). The two rotor engine has the rotor chambers fed by respective lean mixture carburetter barrels 861, 862 and a common rich mixture barrel 863. The barrels 861, 862 have mixture enrichment devices 880, 880A controlled by a control circuit 888 similar to the control circuit of the fourth embodiment. The control circuit also controls an exhaust gas recirculation valve (855) in a passage to one rotor inlet manifold. The engine may be a direct injection reciprocating piston engine. In a rotating piston engine the chambers of one rotor may receive a rich charge alternately or intermittently. The ignition timing may be provided by a pair of contact breakers (301, 302), Fig. 7, or a contactless circuit breaker. During transition from advanced to retarded timing additional retardation is provided which is eliminated after a certain time  period.