Ignition timing control system for internal combustion engines

Claim 1

An ignition timing control system for internal combustion engines comprising: first detecting means, responsive to an intake condition of an engine, for producing a first detection output indicative of the intake condition; second detecting means, responsive to the rotation of said engine, for producing a second detection output indicative of the rotational speed; third detecting means, responsive to movement of the throttle valve of said engine, for producing a third detection output related to the movement of the throttle valve to and from a closed position; first setting means, responsive to said first and second detection outputs, for producing a first setting output indicative of the ignition timing corresponding to the intake condition and the rotational speed of said engine; second setting means, responsive to said third detection output, for producing a second setting output which gradually changes between first and second constant values, said second setting output changing from said first constant value to said second constant value when the throttle valve of said engine is opened from the closed condition and changing from said second constant value to said first constant value when the throttle valve of said engine is closed from the open condition; means responsive to said first and second setting outputs for producing an output indicative of ignition timing, said ignition timing output gradually changing, in response to said second setting output, when said throttle valve leaves or enters a fully closed position, so that a resultant advance angle is gradually increased at a rate less than the rate of change of said first setting output when said throttle valve is opened from the fully closed position, and the resultant advance angle is gradually decreased at a rate less than the rate of change of said first setting output when said throttle valve is fully closed thereby to prevent the ignition timing being varied rapidly; and igniting means responsive to said output of said output producing means for producing an ignition spark in synchronization with the corrected ignition timing.

Claim 5

A method for controlling ignition timing for an internal combustion engine comprising the steps of: generating an intake pressure signal related to the negative intake pressure of said engine; generating an engine speed signal related to the rotational speed of said engine; generating a throttle valve movement signal related to the movement of the throttle valve of said engine to and from a closed position; producing an ignition timing signal in accordance with said intake pressure signal and said engine speed signal; producing a correction signal in response to said throttle valve movement signal, said correction signal being varied decreasingly from a predetermined value to zero when said throttle valve is opened from a fully closed position, and said correction signal being varied increasingly from zero to said predetermined value when said throttle valve is fully closed from an open position; and correcting said ignition timing signal in response to said correction signal and providing a corrected ignition timing signal such that a resultant advance angle is gradually increased from zero advance angle to a predetermined value when said throttle valve is opened from the fully closed position, and the resultant advance angle is gradually decreased to zero advance angle when said throttle valve is fully closed thereby to prevent the ignition timing being varied rapidly.

Claim 6

A method for controlling ignition timing for an internal combustion engine comprising the steps of: generating an intake pressure signal related to the negative intake pressure of said engine; generating an engine speed signal related to the rotational speed of said engine; generating a throttle valve movement signal related to the movement of the throttle valve of said engine to and from a closed position; producing an ignition timing signal in accordance with said intake pressure signal and said engine speed signal; producing a correction signal in response to said throttle valve movement signal, said correction signal being varied decreasingly from a predetermined value to zero when said throttle valve is opened from a fully closed position, and said correction signal being varied increasingly from zero to said predetermined value when said throttle valve is fully closed from an open position; and correcting said ignition timing signal in response to said correction signal and providing a corrected ignition timing signal such that a resultant advance angle is gradually increased from zero advance angle to a predetermined value when said throttle valve is opened from the fully closed position, and the resultant advance angle is gradually decreased to zero advance angle when said throttle valve is fully closed thereby to prevent the ignition timing being varied rapidly.