PURPOSE: To maintain optimal unstability and to ensure operation stability by regulating control amount such that the unstability of engine is maintained at a setting level, and modifying the setting level if the variation rate of unstability against the control amount is high.
CONSTITUTION: Operating condition of an engine E is detected through means 1, and control amount of engine control parameter is set through means 2 corresponding to an output from means 1. Unstability of the engine E is detected through the means 3, and the control amount set through the means 2 is regulated through means 4 such that the unstability is maintained at the setting level corresponding to the output from the means 3. Variation rate of unstability detected through the means 3 against variation of control amount set through the means 2 is detected through means 5. When the variation rate detected through the means 5 exceeds over a predetermined level, the setting level of unstability is modified through means 6. Consequently, the unstability is maintained at an optimal level and the operation stability of the engine E can be ensured even upon variation of control amount.
IMAZU SHIGEKI
YOSHIMURA TAKESHI
KONO YASUSHI
