METHOD TO DETERMINE A FUEL COMPOSITION

• US 20080289401A1
• Filed: 05/23/2008
• Published: 11/27/2008
• Est. Priority Date: 05/23/2007
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: BOERKEL, Wolfgang
• Granted Patent: US 7,963,156 B2
• Time in Patent Office: Days
• US Class Current: 73/61.47
• CPC Class Codes: F02D 19/061 by controlling fuel injectors
• CPC Class Codes: F02D 19/084 Blends of gasoline and alcohols, e.g. E85
• 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 35/023 by determining the cylinder pressure
• CPC Class Codes: F02D 35/028 by determining the combustion timing or phasing
• 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: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

The invention concerns a method to determine the fuel composition of a fuel mixture from a first fuel and a second fuel for the operation of an internal combustion engine, wherein the first and the second fuel have different combustion rates and/or different specific energy contents and wherein the internal combustion engine has at least one pressure sensor in at least one combustion chamber, with which a temporal pressure curve and/or a pressure curve under conditions of angular synchronism is determined. Provision is made according to the invention for the composition of a fuel mixture to be determined from the temporal pressure curve and/or the pressure curve under conditions of angular synchronism of the gas pressure in the combustion chamber, of which there is at least one. A fuel mixture from fuels with different combustion rates exists, for example, in an alcohol-gasoline mixture. Alcohol has a faster combustion process than gasoline. For that reason, the proportion of alcohol in the fuel mixture can, for example, be suggested from the time difference between ignition and maximum pressure in the combustion chamber. The method according to the invention has the advantage, in that the alcohol content can already be determined shortly after cold starting the engine, if a method based on the signal of a lambda probe can not yet be executed because the lambda probe has not yet achieved its operating temperature. It is also particularly advantageous, in that the influence of the alcohol proportion in the fuel mixture can be separated from the errors of the fuel mixture generation, which result from the air and fuel pathways. This is otherwise only possible when using a cost inflating alcohol sensor. Furthermore, the method according to the invention can be implemented in one or in a small number of combustion cycles, while methods based on the signal of the lambda probe require a significantly longer time period. The method can be employed in internal combustion engines, which have a pressure sensor in at least one combustion chamber. Provision can, however, be made for the method to be used in selected or in all of the cylinders of the internal combustion engine.

Claims

1. A method of determining a composition of a fuel mixture from a first fuel and at least a second fuel for operation of an internal combustion engine, wherein the first fuel and at least a second fuel have different combustion rates or different specific energy contents, in that the internal combustion engine has at least one pressure sensor in at least one combustion chamber, wherein the at least one pressure sensor determines a temporal pressure curve or a pressure curve under an angular synchronism condition, the method comprising:

determining the composition of the fuel mixture from the temporal pressure curve during a combustion phase of the internal combustion engine; and

determining the composition of the fuel mixture from the pressure curve under conditions of angular synchronism of a gas pressure in the at least one combustion chamber during a combustion phase of the internal combustion engine.

2. A method according to claim 1, further comprising determining the composition of the fuel mixture from a relative timing difference between an ignition of the internal combustion engine operating under conditions of angular synchronism and a maximum pressure, a combustion focal point, from a relative timing difference between the ignition and any of a plurality of characteristic points of combustion with respect to each other.

3. A method according to claim 1, further comprising determining the composition of the fuel mixture from a rate of a pressure increase occurring at a predetermined point in time or from an angle of rotation of a crankshaft.

4. A method according to claim 1 further comprising determining the composition of the fuel mixture from a time period of at least one of a plurality of phases,

wherein a plurality of phases includes at least an ignition delay phase and a conversion phase and a combustion phase.

5. A method according to claim 1, further comprising determining the composition of the fuel mixture from a maximum pressure in the combustion chamber.

6. A method according to claim 1, further comprising determining the composition of the fuel mixture from a combination of a plurality of characteristics of the temporal pressure curve or a combination of a plurality of characteristics of the pressure curve.

7. A method according to claim 1, further comprising determining the composition of the fuel mixture from an angle of rotation of a crankshaft at a specific point in time of an ignition, wherein an ignition timing is displaced in such a way that a maximum pressure in the combustion chamber, a combustion focal point, or any of a plurality of characteristic values of a combustion cycle is achieved at a predetermined angle of rotation of a crankshaft.

8. A method of using an internal combustion engine having at least one pressure sensor in at least one combustion chamber to determine the composition of a gasoline and an alcohol fuel mixture by determining a composition of a fuel mixture from a first fuel and at least a second fuel for the operation of an internal combustion engine, wherein the first fuel and at least a second fuel have different combustion rates or different specific energy contents, in that the internal combustion engine has at least one pressure sensor in at least one combustion chamber, wherein the at least one pressure sensor determines a temporal pressure curve or a pressure curve under an angular synchronism condition, the method comprising:

determining the composition of the fuel mixture from the temporal pressure curve during a combustion phase of the internal combustion engine; and

determining the composition of the fuel mixture from the pressure curve under conditions of angular synchronism of a gas pressure in the at least one combustion chamber during a combustion phase of the internal combustion engine.

9. A method of using an internal combustion engine having at least one pressure sensor in at least one combustion chamber to determine the composition of a gasoline and a methanol fuel mixture or a gasoline and an ethanol fuel mixture by determining a composition of a fuel mixture from a first fuel and at least a second fuel for the operation of an internal combustion engine, wherein the first fuel and at least a second fuel have different combustion rates or different specific energy contents, in that the internal combustion engine has at least one pressure sensor in at least one combustion chamber, wherein the at least one pressure sensor determines a temporal pressure curve or a pressure curve under an angular synchronism condition, the method comprising:

determining the composition of the fuel mixture from the temporal pressure curve during a combustion phase of the internal combustion engine; and

determining the composition of the fuel mixture from the pressure curve under conditions of angular synchronism of a gas pressure in the at least one combustion chamber during a combustion phase of the internal combustion engine.