Abstract: A spark plug for an internal combustion engine disclosed herein includes a resistive semiconductor body connecting a center electrode and an earth electrode to perform a creeping discharge at low discharge voltages while keeping adequate ignition performances.According to the invention, the spark plug comprises a back electrode at the back of a discharging gap to cause the creeping discharge on surfaces of an electric insulator which is resistant to electrolytic corrosion, thereby improving the durability of the plug and eliminating the trouble of electric waves of noises.

Abstract: A plasma ignition system for a multi-cylinder internal combustion engine each cylinder having a plasma ignition plug, including diesel engine. According to the present invention, in addition to the elements of the conventional plasma ignition system there is provided an oscillation device which generates and outputs a high-frequency oscillating voltage into each of the plasma ignition plugs to be ignited before the plasma ignition timing so that a multiple sparking occurs and therefore the resistance of the plasma ignition plug to be ignited is reduced to facilitate plasma ignition with relatively low plasma ignition energy without misfire even during a high engine load.

Abstract: The invention relates to a swirl-chamber Diesel engine. A swirl-chamber Diesel engine is disclosed which has a main combustion chamber, a swirl chamber, and a communicating passage for connecting them. The problem encountered is that, when the engine runs at low speeds, fuel droplets within the swirl chamber will gather and flow along the communicating passage into the main combustion chamber. To prevent this unfavorable fuel flow, a depression is formed within the swirl chamber to collect the fuel droplets. The depression is disposed adjacent to and communicating with the communicating passage via a rounded lip to provide an arrangement which will make it easy for the combustion gases flow to draw the collected fuel from the depression. Since the fuel is drawn from the depression by the combustion gases flow, carbonization of fuel on the depression wall will not take place.

Abstract: An ignition plug for an internal combustion engine is disclosed which comprises an elongate electrode means inserted at the center of a plug body, another cylindrical electrode means encircling the electrode means and an insulator means provided between the elongate and cylindrical electrode means and forming a small cavity which is in communication with a combustion chamber. A plasma gas is created in the cavity due to the generation of a spark between the elongate and cylindrical electrode means and is jetted into the combustion chamber to ignite the air-fuel mixture therein. A gap into which the burnt gas is introduced is formed between the insulator means and the cylindrical electrode means so as to warm the wall of the cavity and thereby avoid ignition misfiring.

Abstract: An exhaust gas recirculating device in which the intake mixed fuel gas passageway is surrounded by a double wall tube which defines a ring shaped space therebetween. Recirculating exhaust gas is introduced into the ring shaped space to heat the inner tube of the double wall to ease vaporization of the wall stream of fuel and the exhaust gas is blown out from a narrowed outlet of the space so as to well mix the fuel gas mixture and the recirculating exhaust gas.

Abstract: A Diesel engine having a subchamber in the cylinder head in which the exhaust gas recirculating (EGR) passageway is coupled to the subchamber with a valve means controlled in synchronism with the rotation of the engine so that only the minimum necessary amount of EGR gas is present exclusively in the subchamber at the beginning stage of engine combustion in order to decrease the generation of NOx products while maintaining good combustion.

Abstract: The invention relates to a swirl-chamber Diesel engine. A swirl-chamber Diesel engine is disclosed which has a piston formed with a curved groove at its crown and in which a communicating passage, between a main combustion and a swirl chamber, connects tangentially into the swirling air charge within the main combustion chamber. The curved groove has one end which, when the piston is on its top dead center, communicates with the swirl chamber through the communicating passage. It is curved generally along the swirling air charge and has an opposite end widened and arranged so as to direct the subsequent combustion gases toward the center of the main combustion chamber and permit them to diffuse thereabout. With this arrangement, the swirling air charge within the main combustion chamber and the penetrating force of the subsequent combustion gases entering into the main combustion chamber from the communicating passage are fully utilized to encourage the feeding of air to the fuel.

Abstract: A spark ignition reciprocatory internal combustion engine with dual induction system is provided in which at low and intermediate loads when only a primary throttle valve within a primary induction system opens, a primary intake port passage within a cylinder head will direct fluid charge into a combustion chamber in a cylinder to swirl therein as a primary intake valve opens, while, at high loads when a secondary throttle valve within a secondary induction system opens also, a secondary intake port passage within the cylinder head will direct fluid charge into the combustion chamber in the cylinder in such a direction as to impede and reduce the swirling motion of the fluid charge from the primary intake port passage as a secondary intake valve opens, thereby to maintain the volumetric efficiency of the engine at a sufficiently high level. The secondary intake valve is operated to open in synchronization with the opening of the primary intake valve.