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System for diagnosing and controlling high-pressure fuel system for in-cylinder fuel injection engine

  • US 6,138,638 A
  • Filed: 09/01/1998
  • Issued: 10/31/2000
  • Est. Priority Date: 09/03/1997
  • Status: Expired due to Fees
First Claim
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1. A system for controlling an in-cylinder fuel injection engine, wherein a low pressure fuel fed from a low pressure pump is regulated to a predetermined fuel pressure by a low pressure regulator to be fed to a high pressure pump, the pressure of said fuel being raised by said high pressure pump and regulated to a predetermined controlled fuel pressure by a high pressure regulator to feed a high pressure fuel to an injector, and wherein a fuel injection quantity is set on the basis of an engine operating condition, said fuel injection quantity of said fuel being injected directly into a cylinder by the injector, said control system comprising:

  • opening/closing valve means provided in a fuel by-pass passage provided for by passing said high pressure regulator to establish a communication between a high-pressure fuel system and a low-pressure fuel system;

    diagnosing means for monitoring at least one of the behavior of a fuel pressure of said high-pressure fuel system and the relationship between an air-fuel ratio and a fuel injection pulse width for the injector, said diagnosing means determining that said high-pressure fuel system is abnormal when meeting at least one of conditions that said behavior of the fuel pressure is abnormal and that said air-fuel ratio is incompatible with said fuel injection pulse width;

    opening/closing valve control means for closing said opening/closing valve means when said high-pressure fuel system is normal and for opening said opening/closing valve means when said high-pressure fuel system is abnormal;

    fuel injection control means for setting a fuel injection pulse width defining a fuel injection quantity for the injector on the basis of the engine operating condition in accordance with the controlled fuel pressure regulated by said high pressure regulator when said high-pressure fuel system is normal, said fuel injection control means setting the fuel injection pulse width on the basis of the engine operating condition in accordance with the pressure of a low pressure fuel regulated by said low pressure regulator when said high-pressure fuel system is abnormal;

    a fuel pressure correction factor table which uses a fuel pressure in a practical use range of said high-pressure fuel system as a parameter for storing therein a fuel pressure correction factor for correcting the variation in fuel injection quantity based on said fuel pressure; and

    an abnormal period fuel pulse width table which uses an engine speed and an engine load as parameters for storing therein a fuel injection pulse width suited to obtain a required fuel injection quantity at the pressure of a low pressure fuel regulated by said low pressure regulator,wherein when said high-pressure fuel system is normal, said fuel injection control means sets a basic fuel injection quantity on the basis of the engine operating condition to set a basic fuel injection pulse width, which is used for obtaining said basic fuel injection quantity at a predetermined controlled fuel pressure regulated by said high-pressure regulator or said electromagnetic high-pressure regulator and which defines a basic valve opening period for said injector, on the basis of said basic fuel injection quantity, and said fuel injection control means makes reference to said fuel pressure correction factor table on the basis of the fuel pressure of said high-pressure fuel system to set a fuel pressure correction factor to correct said basic fuel injection pulse width by said fuel pressure correction factor to set a final fuel injection pulse width for the injector, andwherein when said high-pressure fuel system is abnormal, said fuel injection control means makes reference to said abnormal period fuel injection pulse width table on the basis of the engine speed and the engine load to set a final fuel injection pulse width for the injector.

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