Gaseous fuel engine charge density control system

• US 20070079598A1
• Filed: 10/06/2005
• Published: 04/12/2007
• Est. Priority Date: 10/06/2005
• Status: Abandoned Application

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Bailey, Brett, Boley, William
• Application Number:
  US11/245,374
• Publication Number:
  US 20070079598A1
• Time in Patent Office: Days
• US Class Current: 60/278
• CPC Class Codes: F02D 19/023 to adjust the fuel mass or volume flow
• CPC Class Codes: F02D 19/028 by estimation, i.e. without using direct measured parameter of a corresponding sensor
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/1401 characterised by the control or regulation method F02D41/1473, F02D41/1477 take precedence
• CPC Class Codes: F02D 41/144 Sensor in intake manifold
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/146 the characteristics being an NOx content or concentration
• CPC Class Codes: F02M 21/0275 for in-cylinder direct injection, e.g. injector combined with spark plug
• CPC Class Codes: F02M 21/0278 Port fuel injectors for single or multipoint injection into the air intake system
• CPC Class Codes: F02M 21/04 Gas-air mixing apparatus
• CPC Class Codes: F02M 26/06 Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
• CPC Class Codes: F02M 26/15 in relation to engine exhaust purifying apparatus
• CPC Class Codes: F02M 26/19 Means for improving the mixing of air and recirculated exhaust gases, e.g. venturis or multiple openings to the intake system
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A gaseous fuel engine including an exhaust gas recirculation system and method for operating a gaseous fuel engine are provided. The exhaust gas recirculation system has an adjustable flow and is operable to supply exhaust gas to at least one engine cylinder. The engine further includes means for determining a value indicative of a charge density of a combustion mixture that includes gaseous fuel, air and exhaust gas supplied to the at least one cylinder, and adjusting a flow quantity through the exhaust gas recirculation system based at least in part on the value.

Claims

1. A gaseous fuel engine comprising:

means for supplying a gaseous fuel to said gaseous fuel engine which is gaseous upon delivery to said engine and supplied to a plurality of cylinders of said gaseous fuel engine;

an exhaust gas recirculation system having an adjustable flow, said system being operable to supply exhaust gas to at least one engine cylinder; and

means for determining a value indicative of a density of a gas mixture supplied to said engine, and adjusting a flow quantity through said exhaust gas recirculation system based at least in part on said value.

2. The gaseous fuel engine of claim 1 comprising:

an intake manifold;

an exhaust gas outlet pathway;

at least one sensor disposed in at least one of said intake manifold and said outlet pathway; and

wherein said means for determining a value indicative of a density of a gas mixture supplied to said engine includes a processor configured to communicate with said at least one sensor and operable to determine a charge density of gases supplied to the cylinders.

3. The gaseous fuel engine of claim 2 wherein:

said at least one sensor includes a pressure sensor and a temperature sensor disposed in said intake manifold;

said processor is configured to communicate with said pressure sensor and said temperature sensor and operable to determine said value based at least in part on a ratio of gas pressure to gas temperature in said manifold, or the inverse of said ratio.

4. The gaseous fuel engine of claim 3 further comprising:

a lambda sensor disposed in said exhaust gas outlet pathway;

a fuel metering valve disposed upstream said intake manifold and coupled with said processor, said fuel metering valve being operable to adjust a fuel flow to said intake manifold and to adjust an actual fuel to air ratio of the engine toward a desired fuel to air ratio;

said processor is configured to communicate with said lambda sensor, and operable to set said exhaust gas recirculation flow quantity based in part on said desired fuel to air ratio.

5. The gaseous fuel engine of claim 4 wherein said processor is operable to set said exhaust gas recirculation flow quantity to adjust a density of the gas mixture independent of a gaseous fuel type.

6. The gaseous fuel engine of claim 1 comprising:

a three-way catalyst disposed in said exhaust gas outlet pathway, said exhaust gas recirculation loop connecting with said exhaust gas outlet pathway downstream said three-way catalyst;

a lambda sensor also disposed in said exhaust gas outlet pathway;

a fuel metering valve operably coupled with said lambda sensor, said fuel metering valve being operable to adjust an actual air to fuel ratio of the engine toward a stoichiometric air to fuel ratio.

7. An article comprising:

a computer readable data storage medium;

an exhaust gas control algorithm recorded on said medium, said control algorithm including means for determining a value indicative of a density of a gas mixture in an internal combustion engine;

said control algorithm further including means for setting an engine exhaust gas recirculation flow quantity in the engine based at least in part on said value; and

said article being further configured to control supplying a gaseous fuel to said internal combustion engine which is gaseous upon delivery to said gaseous fuel engine.

8. The article of claim 7 wherein said control algorithm includes means for determining a charge density of a gas mixture supplied to cylinders of said engine based at least in part on a pressure and temperature of the gas mixture in an intake manifold of said engine.

9. The article of claim 8 wherein said control algorithm includes means for determining said value based on a ratio of pressure to temperature of a mixture of fuel, air and exhaust gas in said intake manifold or the inverse of said ratio at said intake manifold.

10. The article of claim 9 comprising:

a control algorithm including means for determining a fuel to air ratio in said internal combustion engine and adjusting the same toward a desired fuel to air ratio; and

said control algorithm further including means for setting said exhaust gas recirculation flow quantity based in part on said desired fuel to air ratio.

11. The article of claim 9 wherein said control algorithm includes means for accessing a plural parameter look-up table recorded on said computer readable data storage medium, and calculating and setting an exhaust gas recirculation flow quantity based at least in part on:

a plurality of charge density values in said table;

a plurality of engine speed values in said table; and

a plurality of engine load values in said table.

12. A method of operating a gaseous fuel engine having an exhaust gas recirculation system comprising the steps of:

supplying a gaseous fuel to the engine which is gaseous upon delivery to said gaseous fuel engine;

determining a value indicative of a desired density of a gas mixture supplied to the engine; and

setting a NOx output of the engine within a predetermined range by setting an exhaust gas recirculation flow quantity based at least in part on said value.

13. The method of claim 12 wherein the step of determining a value includes measuring a temperature and a gas pressure of a mixture containing, air and exhaust gas.

14. The method of claim 13 wherein the step of setting a NOx output of the engine includes referencing a pre-recorded set of NOx values corresponding to a given charge density of a mixture of gaseous fuel, air and exhaust gas.

15. The method of claim 14 comprising:

measuring an actual NOx output of the engine at a given speed and load; and

determining an offset value of the actual NOx output relative to the prerecorded set of NOx values.

16. The method of claim 14 wherein the step of setting a NOx output of the engine comprises adjusting a charge density of the engine within a predetermined range between an engine knock charge density and an engine misfire charge density.

17. The method of claim 15 wherein the method comprises the step of measuring a fuel to air ratio of the mixture of fuel, air and exhaust gas and adjusting the same toward a stoichiometric fuel to air ratio.