Abstract: A fuel injection control system for an internal combustion engine has at least one unit injector for injecting fuel into each cylinder, and an actuator provided for each of the at least one unit injector for varying the stroke of a plunger of the each unit injector. When a rise ratio of rotational speed of the engine calculated exceeds a predetermined value, the actuator is shifted to a predetermined position, thereby preventing an abnormal rise in the rotational speed of the engine. Similarly, when a no-load condition of the engine is detected, the actuator is shifted to a predetermined position.

Abstract: A valve-operating system for an internal combustion engine, which system includes a valve-driving piston slidably received in a cylinder body and operatively connected at one end of the piston to an engine valve spring-biased in a closing direction. A check valve and an orifice are interposed between a hydraulic pressure generating means for generating an oil pressure for causing opening of the engine valve and a damper chamber defined between the cylinder body and the valve-driving piston. The check valve permits only the flow of working oil from the hydraulic pressure generating means to the damper chamber. The orifice restricts the return of working oil from the damper chamber to the hydraulic pressure generating means. The orifice is made sufficiently short relative to its width to reduce the influence due to viscosity variations of the working oil to an extremely small level.

Abstract: A piston for an internal combustion engine is disclosed which comprises a piston main body having an opening in the top surface thereof and a cavity forming member having a combustion chamber form the top surface thereof which is mounted in the opening of the piston main body. The diameter of the cavity forming member is less then the diameter of the piston main body and the top surface of the cavity forming member is in alignment with the top surface of the piston main body. A piston pin is mounted in the piston main body and the cavity forming member is supported by the piston pin. Further a connecting rod is connected to the piston pin whereby the connecting rod is coupled to the main piston body.

Abstract: The invention discloses a carburetor percolation prevention system which utilizes an electrically controlled fuel drain valve disposed in a fuel drain passage between the carburetor float chamber and the fuel tank. The electrical fuel drain valve is opened only when the engine condition sensor and the temperature sensor indicate that both the ignition switch is de-energized and the temperature near the float chamber exceeds a predetermined level.

Abstract: A supercharger control system for an internal combustion engine wherein a control valve is advantageously placed in the inlet bypass of the supercharger. The control valve is activated and controlled by a combination of the throttle position and the pressure differential within the intake manifold. A linkage including a lost-motion mechanism connects the control valve to the engine throttle valve for limiting the closing of the control valve for supercharging to corresponding open positions of the throttle valve. A pressure differential device urges the control valve toward a closed position for supercharging upon the occurrence of a lower pressure at a venturi portion of the air intake than at a portion upstream thereof at the supercharger outlet.

Abstract: A device for mounting fuel injection systems and particularly fuel injection nozzles and a fuel supply manifold. The device includes U-shaped structures having coaxial, spaced holes into which are mounted fuel injection nozzles. The fuel supply manifold is fixed to the structure such that it is in alignment with the nozzles to provide fuel thereto. The nozzles are mounted and sealed by resilient members positioned and compressed within the coaxial holes to provide vibration isolation, thermal isolation and accommodation of dimensional control anomolies in what is therefore allowed to be crudely fabricated components.

Abstract: A fuel supply apparatus in an internal combustion engine in which a venturi provided in the intake passage of the engine is provided with a fuel discharging opening, and the discharge opening is in communication with a fuel-air mixture producing source at which the fuel-air mixture is produced by mixing the external air and the injection fuel injected from a fuel injection nozzle.

Abstract: Constant differential pressure valves, one for each cylinder of the engine, supply liquid fuel to the injection nozzles. The liquid fuel supplied to the valves is delivered from a chamber within a metering member mounted to turn within the bore of a stationary sleeve. A plate carried by the metering member has notches on its periphery which cooperate with openings in the enclosing sleeve to form variable orifices. The metering member is turned in proportion to the rate of air flow through an air intake passage for the engine.

Abstract: An exhaust purifying system for a multi-cylinder four-cycle internal combustion engine operating on an intake mixture leaner than stoichiometric employs first preliminary reaction chambers receiving exhaust gases from ports connected to cylinders having successive firing order. The exhaust gases are then delivered from said first preliminary reaction chambers to a single second preliminary reaction chamber and then to a catalytic reaction chamber containing oxidative catalysts of base metals, and then finally to an oxidative reaction chamber. The intake mixture for the engine is heated from exhaust gases in the oxidative reaction chamber. This particular succession of chambers causes the temperature of the exhaust gases to increase to above 800.degree. C.

Abstract: A system is disclosed for preventing overheating of a carburetor of the type which is placed with an intake manifold above an exhaust manifold. A heat insulating plate is disposed substantially horizontally between the intake manifold and the carburetor. This plate extends to substantially cover the area above the exhaust manifold. A substantially vertical plate extends upwardly from the heat insulating plate at an edge thereof most distant from the engine. A path is thereby created for the convection currents from the exhaust manifold to bypass the carburetor.