Fuel composition sensor diagnostic apparatus

• US 5,261,270 A
• Filed: 08/15/1991
• Issued: 11/16/1993
• Est. Priority Date: 08/15/1991
• Status: Expired due to Fees

• Current Assignee: General Motors of Canada Limited (General Motors Company), Delco Electronics Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors of Canada Limited (General Motors Company), Delco Electronics Corporation (Motors Liquidation Co. GUC Trust), General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Gonze, Eugene V., Chu, Larissa C., Orminski, John K.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): Dombroske, George M.
• Application Number:
  US07/745,624
• Time in Patent Office: 824 Days
• Field of Search: 73/61.43, 73/61.44, 73/61.59, 73/53, 324/663, 324/685, 361/280, 361/281, 123/494, 123/1 A
• US Class Current: 73/61.43
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02M 43/00 Fuel-injection apparatus operating simultaneously on two or more fuels, or on a liquid fuel and another liquid, e.g. the other liquid being an anti-knock additive
• CPC Class Codes: G01N 27/221 by investigating the dielectric properties using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26
• CPC Class Codes: G01N 33/2852 alcohol/fuel mixtures

Abstract

A motor vehicle fuel composition sensor is responsive to a dielectric constant of a mixture of two fuels such as gasoline and methanol to indicate the relative concentrations of each. The sensor is fuel temperature dependent at high concentrations of methanol; and a fuel temperature sensor thus provides a fuel temperature signal for fuel composition signal correction. Diagnostic apparatus stores references defining permissible operating ranges for the fuel temperature and fuel composition sensor outputs and compares the sensor outputs with these ranges to detect abnormal sensor operation. The reference defining the end of the fuel composition sensor range at maximum methanol, however, is corrected for fuel temperature if the fuel temperature sensor output is within range. An out of range signal from either sensor causes a default value to be substituted for fuel composition.

Claims

1. A motor vehicle comprising, in combination:

an engine capable of operating on a fuel mixture comprising a mixture of two fuels having different dielectric constants;

a fuel tank for storing the fuel mixture;

a conduit between the fuel tank and engine for delivering the fuel mixture from the fuel tank to the engine;

a fuel composition sensor in the conduit responsive to a dielectric constant of the fuel mixture to indicate the relative concentrations of the two fuels, the sensor being fuel temperature dependent at high concentrations of one of the two fuels;

an engine controller responsive to the fuel composition sensor for controlling the delivery of the fuel mixture to the engine;

memory apparatus effective to store (1) a fuel composition sensor limit reference representing a limiting value for the sensor indicated concentration of the one fuel at a predetermined fuel temperature, (2) a temperature correction factor as a function of fuel temperature, and (3) a default fuel composition value;

diagnostic processor apparatus comprising (1) means for deriving a value of the temperature correction factor in response to the output of the fuel temperature sensor, (2) means for generating a corrected fuel composition sensor limit reference by modifying the stored fuel composition sensor limit reference in response to the derived value of the temperature correction factor, and (3) means for comparing the fuel composition sensor output with the corrected fuel composition sensor limit reference;

the engine controller being responsive to the diagnostic processor apparatus to substitute the default fuel composition value for the fuel composition sensor output if the fuel composition sensor output exhibits a predetermined magnitude relative to the corrected fuel composition sensor limit reference.

2. A motor vehicle according to claim 1 wherein the fuels are gasoline and methanol and the one of the fuels is methanol.

3. A motor vehicle comprising, in combination:

an engine capable of operating on a fuel mixture comprising a mixture of gasoline and alcohol;

a fuel tank for storing the fuel mixture;

a conduit between the fuel tank and engine for delivering the fuel mixture from the fuel tank to the engine;

a fuel composition sensor in the conduit responsive to a dielectric constant of the fuel mixture to indicate the relative concentrations of the two fuels, the sensor being fuel temperature dependent at high alcohol concentrations and high fuel temperature;

a fuel temperature sensor responsive to the temperature of the fuel mixture in the fuel composition sensor;

an engine controller responsive to the fuel composition sensor for controlling the delivery of the fuel mixture to the engine;

memory apparatus effective to store (1) maximum and minimum fuel temperature sensor references defining a good temperature sensor window therebetween, (2) a first alcohol fuel composition sensor limit reference, (3) a temperature correction factor as a function of fuel temperature, and (4) a default fuel composition value;

first diagnostic processor apparatus comprising means for comparing the fuel temperature sensor output with at least one of the maximum and minimum fuel temperature sensor references to determine whether the fuel temperature sensor output is within the good fuel temperature sensor window,

the engine controller being responsive to the first diagnostic processor apparatus to substitute the default composition value for the fuel composition sensor output when the fuel temperature sensor output is not within the good fuel temperature sensor window; and

second diagnostic processor apparatus comprising means effective only when the fuel temperature sensor output is within the good fuel temperature sensor window for (1) deriving a value of the temperature correction factor in response to the output of the fuel temperature sensor, (2) generating a corrected alcohol fuel composition sensor limit reference by modifying the stored alcohol fuel composition sensor limit reference in response to the derived value of the temperature correction factor, and (3) comparing the fuel composition sensor output with the corrected alcohol fuel composition sensor limit reference,

the engine controller being responsive to the second diagnostic processor apparatus, if the fuel composition sensor output exhibits a predetermined magnitude relative to the corrected alcohol fuel composition sensor limit reference, substituting the stored default fuel composition value for the fuel composition sensor output.

4. A motor vehicle according to claim 3 in which the alcohol is methanol.