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Constant-speed multi-pressure fuel injection system for improved dynamic range in internal combustion engine

  • US 7,775,191 B2
  • Filed: 01/14/2008
  • Issued: 08/17/2010
  • Est. Priority Date: 05/10/2002
  • Status: Expired due to Fees
First Claim
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1. A method of controlling a fuel injection system of an internal combustion engine having an engine control module and a fuel pump for supplying pressurized fuel from a reservoir through a fuel line to a plenum in fluid communication with at least one fuel injector controlled by electronic pulse width to inject fuel pulses q to the engine, wherein the fuel injection system includes two fuel by-pass paths operable to divert a portion of the flow of fuel from the fuel line upstream of the plenum back to either the reservoir or an inlet of the fuel pump, each by-pass path having a binary control valve and a flow constraint provided by an orifice of predetermined diameter, a needle-valve-like device, or a device compressing the fuel by-pass path, wherein a first fuel pressure level PH1 in the fuel line is defined when the control valve of only one of the two fuel by-pass paths is closed, a second or the highest fuel pressure level PH2 in the fuel line is defined when the control valves of both fuel by-pass paths are closed, and a third or the lowest fuel pressure level PL in the fuel line is defined when the control valves of both fuel by-pass paths are open, the method comprising the steps of:

  • A. setting a fuel pump drive, voltage or current, for operating the fuel pump at a predetermined substantially constant speed;

    B. communicating with the engine control module;

    detecting engine operating conditions, including but not limited to fuel pressure, engine speed, vehicle speed and throttle position, while the engine is running;

    determining the engine fuel demand Q and amount of air flow for the engine, and coordinating operations including throttle valve and air accessories, turbocharger or supercharger, to provide the amount of air flow for adequate fuel/air mix in accordance with the detected operating conditions;

    C. calculating the size of the fuel pulses q for satisfying the engine fuel demand Q;

    D. detecting the fuel pressure level in the fuel line;

    E. determining the electronic pulse width for the fuel pulses q to be sent to the fuel injector at the detected pressure level in accordance with the fuel demand Q; and

    F. selecting one of the three pressure levels so that varying pulse width at the selected pressure for fuel pulse q operable within the full range of detected driving conditions for the next fuel injection cycles until the driving condition changes.

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