Abstract: In a fuel injection system for a vehicle engine, the fuel injection is controlled in a feedback mode when no abnormality occurs in the control system, and it is controlled in an open loop mode by a limp home circuit when any abnormality in the control system is detected by a watch dog timer. The vehicle may thus be slowly driven to a safe or proper place for servicing. The limp home circuit includes fuel cutoff means for interrupting the fuel supply to the engine in the open loop mode of operation when the rotational speed of the engine exceeds a predetermined value.

Abstract: A rotation sensing system includes a rotation sensor for outputting sinusoidal pulses, a waveform shaping circuit for shaping each of the sinusoidal pulses into a rectangular pulse, and a microcomputer for receiving an output of the waveform shaping circuit. In the microcomputer, the rectangular pulse appearing in the output of the waveform shaping circuit is processed so as to obtain information on the rotation of an object to be sensed, and also a malfunction of the rotation sensor is detected. Namely, when the rectangular pulse is not inputted into the microcomputer during a set time period, and at the same time when the level of the output of the waveform shaping circuit is equal to the level of the rectangular pulse, the microcomputer produces a signal representative of the malfunction of the rotation sensor.

Abstract: In a control circuit, which has a current switching-over circuit including at least four switching transistors for controlling a current flowing through an electromagnetic device, the control circuit has driving circuits each of which drives the switching transistors in such a way that a short circuit does not occur during the switching-over operation thereof.

Abstract: A driving circuit for use in controlling a motor for controlling an air mixing door, an inner and surrounding air change-over door and a mode setting door and the like used in a vehicle air conditioning device, or a motor used in opening or closing of window panes of a vehicle or in opening or closing the door which includes a control transistor for use in controlling a transistor circuit having a transistor to cause both normal and reverse directed currents to flow in a vehicle motor, the control transistor being operated until a specified period of time has elapsed after the power supply switch is turned on, the motor input being shut off by the control transistor so as to prevent erroneous operation of the motor just after the power supply switch is turned on or to prevent the production of a chattering sound caused by the operation of gear trains with the motor.

Abstract: This invention relates to a control circuit for a motor for use in driving an electrically controlled door such as an air mixing door, inner and outer surrounding air ventilation door, and mode change-over door etc. or an electro-magnetic solenoid for operating an injection pump applied in a Diesel engine or another motor for use in opening or closing a window pane etc. and protects the transistors forming the control circuit.

Abstract: In a generator feeding a load that requires a current of special waveform, for example a nuclear fusion reactor laboratory equipment, the field excitation of the generator is controlled to meet the requirement of the load by means of a computer which generates a control signal to provide an optimum excitation to the generator for meeting the requirement of the load.