Fuel composition estimation and control of fuel injection

• US 8,042,384 B2
• Filed: 01/13/2009
• Issued: 10/25/2011
• Est. Priority Date: 07/13/2006
• Status: Expired due to Fees

• Current Assignee: Delphi International Operations Luxembourg S.à r.l.
• Original Assignee: Delphi Technologies Holding S.a.r.l. (Aptiv PLC)
• Inventors: Bailey, Samuel G.
• Primary Examiner(s): Kirkland, III; Freddie
• Application Number:
  US12/319,910
• Publication Number:
  US 20090178474A1
• Time in Patent Office: 1,015 Days
• Field of Search: 731/143.8, 731/144.5, 731/145.5
• US Class Current: 73/114.38
• 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 19/0652 Biofuels, e.g. plant oils
• CPC Class Codes: F02D 19/0684 High pressure fuel injection systems; Details on pumps, rails or the arrangement of valves in the fuel supply and return systems
• CPC Class Codes: F02D 19/088 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 2041/288 for performing a transformation into the frequency domain, e.g. Fourier transformation
• 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 41/3809 Common rail control systems common rail apparatus F02M55/025, F02M63/0225
• CPC Class Codes: F02D 41/40 with means for controlling injection timing or duration
• CPC Class Codes: F02M 37/0064 for engines being fed with multiple fuels or fuels having special properties, e.g. bio-fuels; varying the fuel composition controlling engines working with pluralities of fuels F02D19/06
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for estimating the composition of a fuel within an engine, comprises performing the following steps under ambient conditions: (a′) determining the ambient temperature of the fuel; (a) monitoring the fuel pressure inside a fuel rail of the engine over a period of time; (b) calculating at least one frequency component of the change in fuel pressure; (c) calculating the speed of sound transmission c on the basis of the at least one frequency component; and (d) estimating the composition of the fuel on the basis of the calculated speed of sound transmission at said ambient temperature. Suitably, the speed of sound transmission in the fuel is calculated using the equation: c=fλ, where the wavelength λ of the standing wave with frequency f is 2L, where L is the length of the fuel rail. Also described are methods for estimating the temperature of the fuel at a non-ambient temperature, and determining a fuels physical properties. Methods for controlling a fuel injection system in an engine according to the determined physical properties of the fuel and the resultant fuel injection system are also described.

Claims

1. A method for estimating a composition of a fuel within an engine, comprising performing the following steps under ambient conditions:

(a′

) determining an ambient temperature of the fuel;

(a) monitoring a fuel pressure inside a fuel rail of the engine over a period of time;

(b) calculating at least one frequency component of the change in fuel pressure;

(c) calculating a speed of sound transmission c on the basis of the at least one frequency component; and

(d) estimating the composition of the fuel on the basis of the calculated speed of sound transmission at said ambient temperature

wherein the fuel comprises a biodiesel.

2. The method of claim 1, wherein in step (a′

), said determining the ambient temperature of the fuel involves one or more of;

measuring an ambient temperature of the atmosphere, measuring an ambient temperature of the engine, and measuring the ambient temperature of the fuel directly.

3. The method of claim 1, wherein in step (b) the frequency of the standing wave f in the fuel is calculated from the change in fuel pressure.

4. The method of claim 1, wherein in step (c), the speed of sound transmission c in the fuel is calculated using the equation:

c=fλ

;

wherein the wavelength λ

of the standing wave with frequency f is 2L, where L is the length of the fuel rail.

5. The method of claim 1, wherein said estimating in step (d) is based on a means of data comparison, the data relating to the ambient temperature of the fuel, the calculated speed of sound transmission, and a mean fuel pressure inside the fuel rail;

wherein said means of data comparison optionally includes one or more calibration curve, look-up table, data map, mathematical equation or other system for storing and processing data digitally.

6. The method of claim 1, which is carried out at engine start-up.

7. The method of claim 1, wherein in step (a) said period of time is less than 2 seconds.

8. The method of claim 1, which comprises, under non-ambient conditions, measuring or estimating the temperature of the fuel using a temperature sensor to determine a non-ambient temperature of the fuel.

9. The method of claim 1, which further comprises the steps of:

(e) carrying out steps (a) to (c) under non-ambient conditions; and

(f) estimating a non-ambient temperature of the fuel under the non-ambient conditions on the basis of the fuel composition estimated in step (d) and the speed of sound transmission calculated in step (e).

10. The method of claim 9, wherein the estimating in step (f) is based on a means of data comparison, the data relating to fuel composition, fuel pressure and speed of sound transmission in the fuel at the non-ambient temperature.

11. The method of claim 9, which further comprises estimating at least one physical property of the fuel at said ambient temperature and/or said non-ambient temperature on the basis of the temperature and composition of the fuel.

12. A method for controlling a fuel injection system in an engine, comprising the steps of:

(i) forming the steps of claim 9 to estimate the non-ambient temperature of the fuel within the engine under non-ambient conditions;

(ii) determining at least one physical property of the fuel at the non-ambient temperature; and

(iii) calibrating the start and end times of a fuel injection event controlled by the fuel injection system such that a predetermined mass of fuel is injected in the fuel injection event.

13. The method of claim 12, wherein in step (ii) the at least one physical property of the fuel includes one or more of density, viscosity and isoentropic bulk modulus.

14. A method for controlling a fuel injection system in an engine at engine start-up, comprising the steps of:

(i) forming the steps of claim 1 to estimate the composition of the fuel within the engine;

(ii) determining at least one physical property of the fuel at ambient temperature; and

(iii) calibrating the start and end times of a fuel injection event controlled by the fuel injection system such that a predetermined mass of fuel is injected in the fuel injection event.

15. The method of claim 1, wherein in step (a′

), said determining the ambient temperature of the fuel involves one of measuring an ambient temperature of the atmosphere and measuring an ambient temperature of the engine.

16. A method for estimating a composition of a fuel within an engine, comprising performing the following steps under ambient conditions:

(a′

) determining an ambient temperature of the fuel;

(a) monitoring a fuel pressure inside a fuel rail of the engine over a period of time;

(b) calculating at least one frequency component of the change in fuel pressure;

(c) calculating a speed of sound transmission c on the basis of the at least one frequency component; and

(d) estimating the composition of the fuel on the basis of the calculated speed of sound transmission at said ambient temperature.

17. A fuel injection control system for an engine having one or more engine cylinders, comprising:

means for estimating a composition of the fuel within an engine at ambient conditions;

means for estimating at least one physical property of the fuel under the ambient conditions on the basis of the estimated fuel composition;

means for estimating mass-flow rate of the fuel under the ambient conditions; and

means for adjusting the start and end points of a fuel injection event controlled by the fuel injection system on the basis of the mass-flow rate of the fuel, such that a predetermined mass of fuel is injected into the one or more engine cylinders in said fuel injection event at start-up;

and optionally which further comprises;

means for estimating a temperature of the fuel within an engine under non-ambient conditions;

means for estimating at least one physical property of the fuel under the non-ambient conditions on the basis of the non-ambient temperature;

means for estimating mass-flow rate of the fuel under the non-ambient conditions; and

means for adjusting the start and end points of a fuel injection event controlled by the fuel injection system on the basis of the mass-flow rate, such that a predetermined mass of fuel is injected into the one or more engine cylinders in said fuel injection event under non-ambient conditions.

18. The fuel injection control system of claim 17, wherein said means for estimating at least one physical property of the fuel under the ambient and/or the non-ambient conditions comprises a means of data comparison, the data relating to one or more of the following:

fuel composition, fuel pressure, fuel temperature and speed of sound transmission;

wherein said means of data comparison optionally includes one or more calibration curve, look-up table, data map, mathematical equation or other form of storing and processing data digitally.

19. The fuel injection control system of claim 17, wherein the means for estimating the mass-flow rate of the fuel comprises a means of data comparison, the data relating to one or more physical property of the fuel.

20. The fuel injection control system of claim 17, wherein the one or more physical property of the fuel include one or more of density, viscosity and isoentropic bulk modulus.