CYLINDER INTERNAL PRESSURE DETECTING DEVICE FOR ENGINE

摘要

PROBLEM TO BE SOLVED: To accurately detect the cylinder internal pressure by providing a sensor element unit and a control means for changing a time constant of an integrating means in response to an engine parameter detected by an operating condition detecting means. SOLUTION: Each cylinder internal pressure sensor 11-14 as operating condition detecting means has a sensor element unit 2 formed of a piezoelectric element and an amplifying unit 3. A control signal generating circuit changes a resistance value of a resistor 15 and capacity of a capacitor 16 so as to obtain the preset time constantτ. An integrating circuit 11 integrates the output signal with the voltage signal from the sensor element unit 2 while using the time constantτ, and this integrated voltage signal is amplified by a non-inversion amplifying circuit 12 and supplied to a control circuit 20 as the cylinder internal pressure detecting signal for showing the cylinder internal pressure. With this structure, since the time constantτis changed in response to the engine parameter, cylinder internal pressure can be accurately detected.