METHOD FOR THE ONBOARD DETERMINATION OF THE VOLATILITY OF A FUEL

• US 20090114288A1
• Filed: 12/19/2006
• Published: 05/07/2009
• Est. Priority Date: 12/22/2005
• Status: Abandoned Application

• Current Assignee: Inergy Automotive Systems Research (Societe Anonyme) (Solvac SA)
• Original Assignee: Inergy Automotive Systems Research (Societe Anonyme) (Solvac SA)
• Inventors: Garabedian, Scott, McCleary, Ryan, Hill, David, Behar, Ron, Grant, Eric, Mehta, Saurin
• Application Number:
  US12/298,846
• Publication Number:
  US 20090114288A1
• Time in Patent Office: Days
• US Class Current: 137/88
• CPC Class Codes: F02D 19/0628 Determining the fuel pressure, temperature or flow, the fuel tank fill level or a valve position
• CPC Class Codes: F02D 19/0636 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 19/0649 Liquid fuels having different boiling temperatures, volatilities, densities, viscosities, cetane or octane numbers
• CPC Class Codes: F02D 19/0665 Tanks, e.g. multiple tanks
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02D 2200/0612 determined by estimation
• 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 41/047 Taking into account fuel evaporation or wall wetting; special correction after fuel cut-off F02D41/126
• CPC Class Codes: F02D 41/064 at cold start F02D41/067 takes precedence
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y10T 137/2499 Mixture condition maintaining or sensing

Abstract

Method for the determination of the volatility of a fuel stored in a fuel tank which is part of a fuel system controlled by a fuel system control unit (FSCU) and comprising pressure, temperature and fuel level sensors, according to which the FSCU uses the ideal gas law and measurements performed by the sensors in order to predict the distillation curve and/or the Driveability Index (DI) of the fuel; use of said method for adjusting the amount of fuel to be injected in a mixing chamber of an internal combustion engine of a motor vehicle.

Claims

1. A method for the determination of the volatility of a fuel stored in a fuel tank which is part of a fuel system controlled by a fuel system control unit (FSCU) and comprising pressure, temperature and fuel level sensors, according to which the FSCU uses the ideal gas law and measurements performed by the sensors in order to predict the distillation curve and/or the Driveability Index (DI) of the fuel.

2. The method according to claim 1, wherein the fuel system comprises a venting line communicating with the fuel tank by means of at least one venting valve and a refilling event sensor, said method comprising the steps of

a. sensing the end of a refilling event using the refilling event sensor;

b. closing the venting valve so that no gas can escape the fuel tank;

c. measuring and recording the temperature, pressure and fuel level using the FSCU;

d. computing the number of moles (n0) of fuel evaporated at the refilling temperature (T0) using the above measured values and an algorithm stored in the FSCU, to get a first point of the distillation curve;

e. measuring and recording again the temperature, pressure and fuel level after a while, when the fuel has reached a higher temperature (T1) and when the engine is running in a non-purge event;

f. computing the number of moles (n1) of fuel evaporated at said higher temperature (T1) to get a second point of the distillation curve;

g. computing at least part of the distillation curve (fx as a function of Tx, where fx is the fraction of fuel evaporated at the temperature Tx) of the stored fuel using the 2 measured/computed points (i.e. (f0, T0) and (f1, T1)); and

h. storing said curve.

3. The method according to claim 2, wherein the distillation curve is computed by linear extrapolation of the 2 available points.

4. The method according to claim 3, wherein the distillation curve is compared with master distillation curves stored in the FSCU and wherein based thereon, the FSCU predicts a DI value.

5. A method for adjusting the amount of fuel to be injected in a mixing chamber of an internal combustion engine of a motor vehicle, said method comprising the steps of

determining the distillation curve and/or the DI of the fuel using a method according to claim 1;

and

adjusting the amount of fuel to be injected in the mixing chamber as a function of the temperature inside the mixing chamber according to said distillation curve and/or DI.

6. The method according to claim 5, wherein the internal combustion engine has a control unit (ECU) which calculates the required air/fuel ratio to be fed to the engine, and wherein the amount of fuel injected in the mixing chamber is adapted by the ECU in function of the temperature in said mixing chamber and according to the information on the distillation curve and/or DI it receives from the FSCU.

7. The method according to claim 5, wherein the FSCU categorizes the fuel in one of three fuel kinds (fuel type 1, 2 or 3) corresponding respectively to low DI fuels (1), nominal DI fuels (2), and high DI fuels (3) and wherein this information is sent to the ECU, which modifies the fuel supply curves based on this information.