United States Patent
US Patent 6209385: Method and system for determining air/fuel ratio…
US 6209385 · granted 2001-04-03
Abstract
A computerized method and system are provided for determining air/fuel ratio of an engine's combustion process from its exhaust emissions wherein alternative methods for calculating the amount of water in the exhaust emissions are available according to the measurement situation and/or the preference of the user. The calculation types may include calculation types such as the Brettschneider/Spindt calculation type, the Simons calculation type or the no O.sub.2 calculation type. Pop-up menus on a computer monitor are used for selecting the basic calculation type. The algorithm of the present invention preferably uses a fixed point iteration wherein an initial value is assumed for oxygen gas which is then used to calculate water moles and then subsequently the water moles is used to calculate another oxygen value. This is repeated until the new value for oxygen gas is no longer significantly different than the old value for oxygen gas. This happens typically after just a few iterations.
| Patent Number | 6209385 |
|---|---|
| Title | Method and system for determining air/fuel ratio of an engine's combustion process from its exhaust emissions |
| Filed | 1996-06-27 |
| Granted | 2001-04-03 |
| Inventor(s) | Silvis; William M. |
| Assignee | Horiba Instruments, Inc. |
| Number of Claims | 48 |
Abstract
A computerized method and system are provided for determining air/fuel ratio of an engine's combustion process from its exhaust emissions wherein alternative methods for calculating the amount of water in the exhaust emissions are available according to the measurement situation and/or the preference of the user. The calculation types may include calculation types such as the Brettschneider/Spindt calculation type, the Simons calculation type or the no O.sub.2 calculation type. Pop-up menus on a computer monitor are used for selecting the basic calculation type. The algorithm of the present invention preferably uses a fixed point iteration wherein an initial value is assumed for oxygen gas which is then used to calculate water moles and then subsequently the water moles is used to calculate another oxygen value. This is repeated until the new value for oxygen gas is no longer significantly different than the old value for oxygen gas. This happens typically after just a few iterations.
Claim 1
A computer-implemented method for determining air/fuel ratio of an engine's combustion process from its exhaust emissions, the method comprising the steps of: taking a sample of the exhaust emissions from an operating engine to obtain exhaust gases and water; measuring concentration of the exhaust gases in the sample, and providing corresponding exhaust gas concentration data; selecting a calculation type from a predetermined set of calculation types stored in a computer system, including a computer; calculating with the computer an amount of water produced in the combustion process based on the selected calculation type and the exhaust concentration data; calculating with the computer an amount of oxygen used in the combustion process based on the amount of water produced in the combustion process and the exhaust gas concentration data; calculating with the computer the air/fuel ratio based on the calculated amount of oxygen; and displaying the air/fuel ratio on a display coupled to the computer.
Claims
48 totalA computer-implemented method for determining air/fuel ratio of an engine's combustion process from its exhaust emissions, the method comprising the steps of: taking a sample of the exhaust emissions from an operating engine to obtain exhaust gases and water; measuring concentration of the exhaust gases in the sample, and providing corresponding exhaust gas concentration data; selecting a calculation type from a predetermined set of calculation types stored in a computer system, including a computer; calculating with the computer an amount of water produced in the combustion process based on the selected calculation type and the exhaust concentration data; calculating with the computer an amount of oxygen used in the combustion process based on the amount of water produced in the combustion process and the exhaust gas concentration data; calculating with the computer the air/fuel ratio based on the calculated amount of oxygen; and displaying the air/fuel ratio on a display coupled to the computer.