Method to determine a cetane number of a fuel

Patent metadata

Field	Value
Publication number	US-10345286-B2
Application number	US-201515516099-A
Country	US
Kind code	B2
Filing date	Sep 29, 2015
Priority date	Oct 1, 2014
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A method of determining the cetane number of a fuel in an internal combustion engine comprising, during running of the engine, i) with respect to one cylinder, performing a routine including a series of injections such that for each injection a quantity of fuel is injected into the cylinder, and during the routine varying the angle at which the injections takes place with respect to crankshaft angle; ii) measuring engine speed at intervals during the series of injections and determining values for changes in engine speed consequent to the injections; iii) determining cetane number from a pre-stored relationship relating the cetane number to changes in engine speed consequent to changes in the test injection angle.

First claim

The invention claimed is:

1. A method of determining the cetane number of a fuel in an internal combustion engine, during running of the engine, the method comprising the steps of:
i) with respect to one cylinder, performing a routine comprising performing a series of injections wherein for each injection a quantity of fuel is injected into said one cylinder, and during said routine varying the angle at which said injections takes place with respect to crankshaft angle;
ii) measuring engine speed at intervals during said series of injections and determining values for changes in engine speed consequent to said series of injections; and
iii) determining a cetane number from a pre-stored relationship relating said cetane number to said changes in engine speed;
said method further comprising normalising said values of step ii) to provide normalised values or modified values which are dimensionless, and step iii) comprises determining cetane number from a pre-stored relationship relating said cetane number to said values that have been normalized.

2. A method as claimed in claim 1 including filtering the values from step ii).

3. A method as claimed in claim 1 wherein for a given injection of said series of injections, a given change in engine speed of said changes in engine speed is defined as the difference in engine speed consequent to said give injection from a previously measured engine speed which is subsequent to the previous injection of said series of injections.

4. A method as claimed in claim 1 wherein step ii) further includes modifying said values by a factor so as to be dependent only on the injected fuel quantity and wherein step iii) comprises determining cetane number from a pre-stored relationship relating said cetane number to said values modified by a factor.

5. A method as claimed in claim 4 further comprising normalising said modified values of step ii) to provide normalised modified values which are dimensionless, and step iii) comprises determining cetane number from a pre-stored relationship relating said cetane number to said normalized modified values.

6. A method as claimed in claim 5 wherein said normalizing comprises dividing said modified values by the equivalent modified value of speed change at a particular timing angle.

7. A method as claimed in claim 1 wherein said normalizing comprises dividing said values by the equivalent value of speed change at a particular timing angle.

8. A method as claimed in claim 1 wherein one injection of said series of injections is performed during each engine cycle.

9. A method as claimed in claim 1 wherein no fuel is injected into other cylinders during said routine.

10. A method as claimed in claim 1 wherein consecutive injections of said series of injections are performed at different crankshaft angles in consecutive engine cycles.

11. A method as claimed in claim 1 wherein the timing of said series of injections with respect to the crankshaft angle are increased or decreased monotonically.

12. A method as claimed in claim 1 wherein said routine is performed during deceleration; power off or fuel cut off conditions.

Assignees

• Delphi Tech Ip Ltd

Inventors

• Cochet Thierry
• Bacq Jean-Michel

Classifications

• G01N33/2829 Primary

  Mixtures of fuels · CPC title

• F02D41/0087

  Selective cylinder activation, i.e. partial cylinder operation (deceleration cut-off F02D41/123) · CPC title

• F02D19/0649

  Liquid fuels having different boiling temperatures, volatilities, densities, viscosities, cetane or octane numbers · CPC title

• F02D41/123

  the fuel injection being cut-off · CPC title

• Y02T10/36

  Cross-Sectional Technologies · mapped topic