Abstract: A control unit for use in a vehicle includes a failure detecting apparatus for detecting failures of solenoids which are used for various kinds of controls of the vehicle. The failure detecting apparatus includes a solenoid driving circuit which sequentially supplies currents to the solenoids, and includes an input circuit which receives an output signal from each solenoid which operates normally. When a solenoid doesn't operate normally, no output signal is returned. Therefore, a control circuit of the apparatus detects the absence of the output signal from such solenoid and thereby determines that this solenoid is defective. When the failure of a solenoid is thus detected, the control circuit outputs an alarm signal to the alarm indicator through the alarm driving circuit, the alarm signal identifying the defective solenoid. A light emitting diode corresponding to the defective solenoid may then be lit to visually indicate the failure.

Abstract: A float switch and a control apparatus of an internal combustion engine are disclosed. This float switch comprises a float attached to a main body so as to be vertically swung around one end thereof, a magnetic material fixed to the float, and a contact adapted to be closed or opened in response to the approach or removal of the magnetic material. The float switch is provided in the pathway of a coolant passage and a lubricating oil passage of the engine. The control apparatus has a warning apparatus which is operative in response to an absence signal from the float switch which is indicative of the absence of the fluid that is being sensed, and has a rotating speed control apparatus to reduce the engine speed. The absence of the fluid is informed to the operator by the warning and the speed reduction. A warning apparatus for an outboard engine to control the engine speed when an abnormality occurs is also provided.

Abstract: A reed valve device for a 2-cycle engine includes a valve housing having several ports extending thereinto from a surface thereof. Several reed valves each have one end secured to the housing and can move between a position spaced from the surface and a position disposed against the surface and obstructing a respective port. Two main shafts are rotatably supported on the housing, and are coupled for synchronous rotation by a gear plate arrangement. Each main shaft has thereon a stopper which can move between positions engaging and spaced from the reed valve in response to rotational movement of the associated shaft, engagement of a stopper and a reed valve effecting an increase in a spring constant of the reed valve. When the engine exceeds a predetermined speed, a motor rotates the shafts to move the stoppers into engagement with the reed valves.

Abstract: An exhaust gas reflux apparatus for an internal combustion engine. This apparatus comprises an EGR regulating valve to control the amount of exhaust gas which is refluxed into an intake system of the engine, an ignition coil to detect the rotating speed of the engine; a shift switch to detect the gear position of the change gear; a negative pressure change-over valve arranged in a negative pressure passage; and a control circuit which discriminates a high-speed and high-load operating state of the engine when the rotating speed is over a set speed and the change gear is at a set gear position on the high speed side on the basis of the detection signals from the ignition coil and shift switch. The control circuit controls the change-over valve to stop the reflux of the exhaust gas after expiration of a set time period when the high-load operating state is detected. The EGR regulating valve is thus not subjected to a high temperature for in excess of the set time period.

Abstract: A rotating speed control apparatus for controlling the rotating speed of an internal combustion engine includes: an ignition circuit of a capacitive discharge ignition (CDI) system; an overspeed preventing circuit having a rotating speed detecting circuit for reducing the rotating speed of the engine to a restricted value in response to an overspeed condition; and a cut-off circuit which temporarily inhibits the control of the engine speed by way of an overspeed prevention inhibiting operation and which is automatically returned to a condition in which it can control the engine speed during restarting of the engine after a stop of the engine. The overspeed preventing circuit is cut off by turning on the cut-off circuit when the engine is driven, so that the overspeed preventing function is inhibited. This cut-off circuit is automatically returned to its off-state when restarting the engine after a stop of the engine, thereby allowing an overspeed of the engine to be prevented.

Abstract: A fuel injection control method for an internal combustion engine includes the steps of monitoring the rotating speed of the engine and the velocity of the vehicle after the engine has been started using starting fuel injection, and performing fuel injection in an ordinary manner without performing starting fuel injection in the case where either of the following conditions is met: (1) the engine rotating speed is above a predetermined rotating speed or (2) the engine rotating speed is less than the predetermined speed and the vehicle velocity is simultaneously above a predetermined velocity.

Abstract: In a power switching apparatus of an outboard engine wherein a shifter dog is moved by a shift cam to engage with a forward gear or a reverse gear for rotating a propeller of a boat in the forward or rearward direction, there is provided a clutch mechanism interposed between a shift rod connected to the shift cam and a clutch rod. The clutch mechanism comprises a clutch housing, the diameter of the intermediate portion of an inner opening of the housing being reduced. The housing is formed with large diameter openings at its upper and lower portions.

Abstract: A fuel injection control method for electronically controlling an amount of fuel injected includes the step of performing asynchronous fuel injection control to increase the amount of fuel injected when the following three conditions are satisfied: (1) the engine has shifted from an idling operating state to a running operating state, (2) the rotating speed of the engine is higher than a predetermined speed, and (3) the velocity of the vehicle is higher than a predetermined velocity. A switch from the idling operating state to the running operating state is detected by checking whether an idle contact of a throttle sensor is switched from ON to OFF. The rotating speed is detected at the ignition coil. The velocity of the vehicle is detected using the vehicle velocity sensor.

Abstract: There is a supercharge pressure control apparatus of a supercharged engine. A bypass is provided to bypass a supercharger turbine arranged between the intake and exhaust passages. A waste gate valve is attached at one end of the bypass and is coupled to an actuator having a pressure chamber communicated with a connecting passage which is branched at a branch point into the first and second passages. A first port is formed in the intake passage downstream near a suction inlet of a compressor and a second port is formed in the intake passage downstream of the first port. In the stationary operating state, the connecting passage is communicated with the second passage by the change-over valve, so that a high pressure from the second port acts on the pressure chamber and the supercharge pressure is maintained at a set level.

Abstract: A method of controlling an air-fuel ratio of an air-fuel mixture for an internal combustion engine includes the steps of sensing the intake air temperature and the operating state and rotating speed of the engine using various detectors. When the intake air temperature is above a predetermined temperature, when the engine is in the idle operating state, and when its rotating speed is below a predetermined speed, the control circuit ceases a normal control in which the air-fuel ratio of the air-fuel mixture is controlled to be a value in a theoretical air-fuel ratio range, and instead controls the air-fuel ratio to be a predetermined rich air-fuel ratio. With this method, a decrease in the absolute amount of fuel supplied to the engine due to a reduction in intake air quantity in the idle operating state when the intake air temperature is high is avoided, which in turn prevents a reduction in the rotating speed of the engine and ensures stability of idling.

Abstract: Herein disclosed is a rear suspension mechanism for a motorcycle, in which a swing arm having its one end hinged to a body frame is connected to the body frame in the vicinity of the hinged portion of the swing arm through a bell crank having an eccentric bearing mechanism, and in which a cushion unit is connected between the body frame and one end of the bell crank.

Abstract: An internal combustion engine which devises the opened direction and position of the gas outlet end of a sub-suction path provided separately from a main suction path so as to inject a gas in the circumferential direction of a combustion chamber during the suction stroke, in which the outlet end of the sub-suction path opens within such a range that, in a plane normal to the axis of the cylinder, the line extending in an opened direction of the sub-suction path is at an angle of .+-.20 to 110 degrees with respect to the line joining the center of the suction port and the axis of the cylinder; the distance between the outlet end of the sub-suction path and the face of a suction valve at its closed position is not more than the internal diameter of the main suction path; or the outlet end of the sub-suction path is positioned within a sphere with its center being a spark point of an ignition plug and with the same diameter as the internal diameter of the cylinder and within a range of .+-.

Abstract: A suction system for an internal combustion engine having a sub-suction path for generating a swirl of suction gases in a combustion chamber. The sub-suction path is in addition to the main suction path to be opened or closed by a suction valve. More specifically, in a multicylinder internal combustion engine, path portions for constructing the sub-suction path are formed in a cylinder head, a suction manifold and a carburetor such that the sub-suction path is automatically constituted when the carburetor is connected to the cylinder head through the suction manifold, without further connections being necessary.

Abstract: An intake port structure comprises a cylinder head including combustion chambers and supporting an intake valve and an ignition plug in each of the combustion chambers, the intake valve having a stem slidably supported by the cylinder head, the cylinder head having a joint surface to which an intake manifold is connected. A primary intake passage is defined in the cylinder head and communicates with each of the combustion chambers, the primary intake passage having a primary intake port directed toward the stem and the ignition plug, and an opening at the joint surface. The opening has a central axis extending at an angle smaller than 90.degree. with respect to the joint surface. The primary intake passage is smoothly curved between the primary intake port and the opening. The intake manifold has a plurality of primary manifold branches arranged substantially symmetrically with respect to a central axis of the intake manifold.