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Engine control system

  • US 4,535,740 A
  • Filed: 05/31/1984
  • Issued: 08/20/1985
  • Est. Priority Date: 06/03/1983
  • Status: Expired due to Fees
First Claim
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1. An internal combustion engine in which the ignition timing and the fuel-to-air ratio are determined by an open loop control system including tables (12,22,14) stored in a microcomputer, the tables providing signals indicating predetermined settings of the ignition timing and the fuel to air ratio in dependence upon sensed parameters and in which a closed loop control circuit (16,18,20,24) incorporating an ionisation sensor disposed within a combustion chamber is provided for sensing a burn period duration and applying a correction to one of the signals derived from the tables stored in the microcomputer in dependence upon the sensed burn period duration, characterised in that the closed loop applies a correction to the signal for regulating the fuel-to-air ratio and has a response time substantially greater than the response time of the open loop, and in that changes in the correction effected by the closed loop are permitted only when the engine is operating within a predetermined range for which the operation of the ionisation sensor is accurately representative of the burn period duration.

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