Abstract: An engine is provided with two spark plugs in each combustion chamber to ignite stoichiometric air-fuel mixture mixed with a large proportion of inert gases to lower NOx emission level. The engine is equipped with hydraulic valve lifters which are mechanically connected to intake and exhaust valves to control the valve overlap of the intake and exhaust valves. By the action of the valve lifters, the valve overlaps are increased in the normal driving operation range of the engine to prevent discharge at the terminal stage of exhaust valve opening exhaust gases containing a considerably large amount of hydrocarbons.

Abstract: An air gallery connected to an air pump is formed in the cylinder head of an internal combustion engine. A bore is also formed in the cylinder head to communicate the air gallery with the exhaust port of the engine. Within the bore an air injection nozzle is securely inserted and projected through the wall surface of the exhaust port near the longitudinal axis of the exhaust port.

Abstract: A spark plug is located in a combustion chamber so as to decrease the combustion time of the charge inducted into the combustion chamber. The charge is formed, before inducted into the combustion chamber, by mixing an air-fuel mixture and substantially inert gas such as exhaust gas so that the weight ratio of the fuel combusted in the combustion chamber and the substantially inert gas falls within the range from 1:13.5 to 1:18.5 during normal engine operation.

Abstract: A control system is adapted for an internal combustion engine in which a jet of air is injected into each combustion chamber via a second intake valve during each exhaust cycle and the subsequent intake cycle. The system comprises a source of compressed air having a pressure to be varied in accordance with the engine speed, an injection passageway leading from the source toward each second intake valve and a flow controller operated in accordance with changes in intake manifold vacuum. The flow controller includes a scheduled flow area therethrough to increase, under conditions in which the engine speed is constant, the amount of air passing through the injection passageway in accordance with increasing engine load in such a way as to increase the ratio of air flow through the injection passageway to the intake air flow to the engine under light engine load in order to cope with increasing residual gas fraction within each combustion chamber when the engine idles or operates under deceleration of the vehicle.

Abstract: Control system is adapted for an internal combustion engine in which a jet of air is injected into a combustion chamber via a second intake valve during a period overlapping an exhaust cycle and the subsequent intake cycle for expelling residual gas within the combustion chamber in order to reduce residual gas fraction of charge for the subsequent combustion within the combustion chamber. The system comprises a source of compressed air having a constant pressure, an injection passageway leading from the source toward the second intake valve, a flow control valve fluidly disposed in the injection passageway, and means whereby the flow control valve will vary effective flow area of the injection passageway in response to a signal indicative of the flow rate of fluid passing through the engine induction passageway.

Abstract: Exhaust gases, which are slightly cooler than normal due to NOx suppressing ignition of the charge containing a large amount of recirculated gas by dual spark plugs, are exhausted via a large diameter exhaust valve to reduce the time for which they exceed the speed of sound and transfer heat to the cylinder head to maintain a high CO and HC oxidizing temperature. The exhaust valve is diametrically opposed to the inlet valve and has a cross sectional area of 19 to 24% of the cylinder bore.

Abstract: Each combustion chamber of an internal combustion engine is divided into four generally equal imaginary parts by a longitudinal vertical imaginary plane parallel with the longitudinal axis of the cylinder head of the engine and a lateral vertical imaginary plane perpendicular to the longitudinal vertical imaginary plane. Two spark plugs, and intake and exhaust valves are disposed on the cylinder head wall surface defining the upper part of the combustion chamber, and located at the four generally equal imaginary parts, respectively.

Abstract: A multiple-cylinder spark-ignition internal combustion engine for an automotive vehicle, in which the ratio of the inactive compounds in the mixture gases produced in each combustion chamber to the fuel component in the combustible mixture inducted into the chamber is maintained within a predetermined range and the spark plug for each engine cylinder is arranged so that the flame travel from the spark plug is reduced to a minimum for promoting the combustion reaction to proceed in the least possible time. Improvements are further made in respect of the exhaust gas recirculation rate, the location and measurements of the spark plug, the configurations and measurements of the engine cylinder and the arrangement of the intake and exhaust ports so as to reduce the concentrations of toxic compounds in the exhaust gases without impairing the performance efficiency of the engine.

Abstract: An exhaust gas recirculation system comprises an exhaust gas flow control valve; a vacuum actuator for operation of the flow control valve; and a control apparatus constructed and arranged such that an output vacuum of the control apparatus applied to the vacuum actuator is an amplification of the venturi vacuum modified by the intake manifold vacuum.

Abstract: Flow of secondary air into the exhaust system is regulated by diaphragm assembly controlled valves between an air supply and the exhaust system. The diaphragm assemblies respond to vacuum in the intake air system of the engine.

Abstract: A valve responsive to both venturi vacuum and intake manifold vacuum operates a recirculation valve by means of vacuum amplification.

Abstract: A linkage for pulling a valve stem against resistance of a compression spring comprises three link members; a first link member coaxially fixed to and extending from the stem, a second member pivoted at an end to the extending end of the first member and a third link member pivoted at an end to the second member at an intermediate point of the second member and pivotally mounted on a fixed shaft at the other end. An actuator exerts a constant force on the free end of the second link and rotates the second link about both the pivots for the first and third links, resulting in pulling the valve stem with a progressively increasing force.

Abstract: A plurality of pump elements is progressively increasing the pressure of air to respectively supply air at various pressures into portions in an exhaust gas purifying system requiring secondary air.