Overheat detecting apparatus for engine

Claim 1

An engine ignition timing control apparatus, comprising: a temperature sensor disposed on or in the vicinity of a cylinder head of an engine, warning means for issuing an operator perceptible warning when said temperature sensor detects an overheating state of the engine, and a main control portion responsive to output signals from said temperature sensor for regulating engine speed and driving said warning means in accordance with necessity; said main control portion including starting time ignition timing control means responsive to said output signals from said temperature sensor for controlling spark advancement according to a starting timing from starting of the engine until the occurrence of one of first and second events, and trolling time ignition timing control means responsive to said output signals from said temperature sensor for controlling spark advancement according to a trolling timing different from said starting timing subsequent to the occurrence of one of said first and second events, wherein said first event occurs upon expiration of a first time interval from starting of the engine, and said second event occurs when the engine temperature is in excess of a predetermined temperature before expiration of said first time interval and after expiration of a second time interval which is less than said first time interval.

Claim 3

A method for controlling the operating speed of an engine, comprising the steps of: providing a temperature sensor at a sensor location adjacent a cylinder head of the engine; calculating a rate of increase in engine temperature based on engine temperature information produced by said temperature sensor; and selectively regulating engine speed based on the calculated rate of increase in engine temperature.

Claim 4

A method for controlling the operating speed of an engine, comprising the steps of: providing a temperature sensor at a sensor location adjacent a cylinder head of the engine; calculating a rate of increase in engine temperature based on engine temperature information produced by said temperature sensor; and selectively regulating engine speed based on the calculated rate of increase in engine temperature.