Abstract: A failure diagnosis device for an O2 sensor includes an O2 sensor; a heater driving unit driving a heater heating the O2 sensor; and a diagnosis unit controlling the heater driving unit heating the heater, and diagnosing O2 sensor failure after a given amount of time based on an O2 sensor activation status determination using O2 sensor outputs. The diagnosis unit includes a heater controlling unit controlling the heater driving unit; a time measuring unit measuring time that electric current is supplied to the heater, and time used in determining sensor abnormality; an activation status determining unit determining air/fuel ratio changes from a lean to rich state, or from a rich to lean state based on the O2 sensor output; and a failure determining unit determining sensor abnormality based on outputs from the time measuring unit and the activation status determining unit, thereby diagnosing O2 sensor failure without engine operation.

Abstract: There is provided a fuel injection control apparatus for an internal combustion engine, which includes an O2 sensor and a feedback controller that performs a feedback control of the injection quantity of fuel to the internal combustion engine. The feedback controller performs the feedback control such that the feedback gain set at the time of starting the feedback and which gives operation constant for performing feedback until the air/fuel ratio becomes optimum, is set larger than the feedback gain set for the normal operation period and which gives operation constant for performing feedback in a stable state, and the feedback gain is changed between the control start time and the normal operation period, thereby reducing the time required to attain a stable feedback state and therefore quick transition to the stable state upon starting the control and thus enabling effective reduction of harmful components in exhaust gas.

Abstract: A failure diagnosis device for an O2 sensor includes an O2 sensor; a heater driving unit driving a heater heating the O2 sensor; and a diagnosis unit controlling the heater driving unit heating the heater, and diagnosing O2 sensor failure after a given amount of time based on an O2 sensor activation status determination using O2 sensor outputs. The diagnosis unit includes a heater controlling unit controlling the heater driving unit; a time measuring unit measuring time that electric current is supplied to the heater, and time used in determining sensor abnormality; an activation status determining unit determining air/fuel ratio changes from a lean to rich state, or from a rich to lean state based on the O2 sensor output; and a failure determining unit determining sensor abnormality based on outputs from the time measuring unit and the activation status determining unit, thereby diagnosing O2 sensor failure without engine operation.

Abstract: There is provided a fuel injection control apparatus for an internal combustion engine, which includes an O2 sensor and a feedback controller that performs a feedback control of the injection quantity of fuel to the internal combustion engine. The feedback controller performs the feedback control such that the feedback gain set at the time of starting the feedback and which gives operation constant for performing feedback until the air/fuel ratio becomes optimum, is set larger than the feedback gain set for the normal operation period and which gives operation constant for performing feedback in a stable state, and the feedback gain is changed between the control start time and the normal operation period, thereby reducing the time required to attain a stable feedback state and therefore quick transition to the stable state upon starting the control and thus enabling effective reduction of harmful components in exhaust gas.

Abstract: An ignition control system is provided, which includes: an engine speed detector (101) for calculating an engine speed according to an engine crank angle signal (100); a current supply start controller (102) for outputting a proper current supply start timing signal corresponding to the engine speed to an ignition coil (5); a current supply finish controller (103) for outputting a proper current supply timing signal corresponding to the engine speed to an ignition coil; an ignition coil controller (104) for controlling supply of power to the ignition coil (5) according to the current supply start timing signal and the current supply finish timing signal; and an overspeed determination device (105) for outputting an overspeed determination signal when determining that the engine speed is in excess of a predetermined limit value. The overspeed determination signal prohibits starting the supply of current, and retards the current supply finish timing to such a degree as to decrease engine torque.

Abstract: An ignition control system is provided, which includes: an engine speed detector (101) for calculating an engine speed according to an engine crank angle signal (100); a current supply start controller (102) for outputting a proper current supply start timing signal corresponding to the engine speed to an ignition coil (5); a current supply finish controller (103) for outputting a proper current supply timing signal corresponding to the engine speed to an ignition coil; an ignition coil controller (104) for controlling supply of power to the ignition coil (5) according to the current supply start timing signal and the current supply finish timing signal; and an overspeed determination device (105) for outputting an overspeed determination signal when determining that the engine speed is in excess of a predetermined limit value. The overspeed determination signal prohibits starting the supply of current, and retards the current supply finish timing to such a degree as to decrease engine torque.