Fuel supply control system for an automotive engine

• US 5,469,831 A
• Filed: 11/10/1994
• Issued: 11/28/1995
• Est. Priority Date: 11/12/1993
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Takahashi, Tatsuhiko
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US08/339,194
• Time in Patent Office: 383 Days
• Field of Search: 123/679, 123/680, 123/689, 123/1 A, 123/494
• US Class Current: 123/680
• CPC Class Codes: F02D 19/061 by controlling fuel injectors
• CPC Class Codes: F02D 19/0649 Liquid fuels having different boiling temperatures, volatilities, densities, viscosities, cetane or octane numbers
• CPC Class Codes: F02D 19/088 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 2200/0612 determined by estimation
• CPC Class Codes: F02D 35/00 Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/249 Methods for preventing the loss of data
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A fuel supply control system for an automotive engine determines a property of the fuel, such as the fifty percent distillation temperature T₅₀ thereof, and the fuel injectors of the engine are controlled in accordance with the determined fuel property. When the engine is idling and the coolant water temperature WT of the engine is decreasing, the amplitude X of the feedback correction factor K₂ for proportional-plus-integral control action is measured a number of times, and an average amplitude X₀ thereof is calculated. The property of said fuel is determined on the basis of the thus calculated average amplitude X₀ and the coolant water temperature WT using a two-dimensional map which gives the value of T₅₀ as a function of the amplitude X of the feedback correction factor K₂ and the coolant water temperature WT. The thus determined index T₅₀ is stored in a RAM backed up by a battery. When a new fuel is supplied to the fuel tank, the value of index T₅₀ is cleared to determine the index afresh.

Claims

1. A fuel supply control system for an internal combustion engine, comprising:

fuel supply means for supplying a fuel to said internal combustion engine;

air/fuel ratio sensor means for detecting an air/fuel ratio of a mixture of air and fuel supplied to said internal combustion engine; and

fuel supply control means, having all input coupled to said air/fuel ratio sensor means, for controlling said fuel supply means to adjust said air/fuel ratio to a theoretical ratio using a feedback control method based on an output of said air/fuel ratio sensor means;

wherein said fuel supply control means includes;

feedback correction factor calculation means for calculating a feedback correction factor from a deviation of said air/fuel ratio detected by said air/fuel ratio sensor means from said theoretical ratio;

amplitude measurement means for determining an amplitude of said feedback correction factor; and

fuel property judgment means for determining a property of said fuel on the basis of said amplitude of said feedback correction factor;

said fuel supply control means controlling said fuel supply means in accordance with said property of said fuel determined by said fuel property judgment means.

2. A fuel supply control system as claimed in claim 1, further comprising:

an idling detector means for detecting an idling state of said internal combustion engine;

wherein said fuel supply control means has an input coupled to said idling detector means and said amplitude measurement means determines said amplitude of said feedback correction factor during a time when said idling detector means detects an idling state of said internal combustion engine.

3. A fuel supply control system as claimed in claim 1, further comprising:

temperature sensor means for detecting a temperature of said internal combustion engine;

wherein said fuel property judgment means has an input coupled to said temperature sensor means and determines said property of said fuel on the basis of said amplitude of said feedback correction factor and said temperature of said internal combustion engine detected by said temperature sensor means.

4. A fuel supply control system as claimed in claim 1, further comprising:

fuel storage means for storing said fuel supplied by said fuel supply means to said internal combustion engine; and

fuel storage supply detector means for detecting an occurrence of fuel supply to said fuel storage means;

wherein said fuel supply control means has an input coupled to said fuel storage supply detector means and includes memory means for storing said property of said fuel determined by said fuel property judgment means, said fuel supply control means deleting said property of said fuel from said memory means when said fuel storage supply detector means detects an occurrence of fuel supply to said fuel storage means.

5. A fuel supply control system as claimed in claim 4, wherein said memory means comprises a RAM backed up by a battery.

6. A fuel supply control system as claimed in claim 1, wherein said amplitude measurement means determines an average of a plurality of amplitudes of said feedback correction factor, and said fuel property judgment means determines said property of said fuel on the basis of said average amplitude of said feedback correction factor.