Engine fuel delivery systems, apparatus and methods

• US 9,022,011 B2
• Filed: 10/27/2008
• Issued: 05/05/2015
• Est. Priority Date: 10/27/2007
• Status: Active Grant

• Current Assignee: Walbro LLC
• Original Assignee: Walbro Engine Management LLC (Sun Capital Partners Incorporated)
• Inventors: Andersson, Martin N., Bejcek, Andrew E., Casoni, Massimo, Galka, William E., Healy, Cyrus M., Pascoli, Alessandro, Roche, Ronald H., Swanson, Mark S., Van Allen, James E., Woody, John C.
• Primary Examiner(s): Gimie, Mahmoud
• Assistant Examiner(s): HAMAOUI, DAVID E
• Application Number:
  US12/739,787
• Publication Number:
  US 20100258099A1
• Time in Patent Office: 2,381 Days
• Field of Search: 123/676, 701/102, 701/103
• US Class Current: 123/676
• CPC Class Codes: F02D 2400/06 Small engines with electronic control, e.g. for hand held tools
• CPC Class Codes: F02D 31/006 for maximum speed control
• CPC Class Codes: F02D 31/009 for maximum speed control
• CPC Class Codes: F02D 35/0053 by means of a carburettor
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• CPC Class Codes: F02M 17/04 having fuel inlet valve controlled by diaphragm
• CPC Class Codes: F02P 3/0815 using digital techniques F02P3/083, F02P3/0846 take precedence

Abstract

A method of operating an engine is disclosed, which includes determining a peak power condition for the engine, measuring a temperature associated with the engine at said peak power condition, comparing the temperature measured with a previously determined temperature associated with a known peak power condition of the engine, determining an offset value based on the comparison made in step, controlling at least one of an air-fuel mixture delivered to the engine or ignition spark timing based on said offset value. Various engine fuel delivery systems, carburetors, fuel injection and control systems also are disclosed.

Claims

1. A method of operating an engine, comprising:

(a) determining a peak power condition for the engine by altering an air-fuel mixture ratio delivered to the engine and monitoring a change in an engine parameter that occurs as a result of the altered air-fuel mixture ratio until said monitored engine parameter indicates the peak power condition of the engine at that time;

(b) measuring a temperature associated with the engine at said peak power condition;

(c) comparing the temperature measured in step (b) with a previously determined temperature associated with a known peak power condition of the engine;

(d) determining an offset value based on the comparison made in step (c); and

(e) controlling at least one of an air-fuel mixture delivered to the engine or ignition spark timing relative to top dead center of a piston of the engine based on said offset value.

2. The method of claim 1 wherein the measured temperature associated with the engine is exhaust gas temperature.

3. The method of claim 1 wherein step (a) includes altering, in more than one increment, the air-fuel mixture ratio delivered to the engine.

4. The method of claim 3 wherein, prior to step (a), an initial air-fuel mixture ratio that is richer than the air-fuel mixture ratio associated with the peak power condition of the engine is delivered to the engine.

5. The method of claim 4 wherein step (a) is accomplished by enleaning the air-fuel mixture ratio delivered to the engine in several increments until the peak power condition of the engine is determined.

6. The method of claim 3 wherein the increments are of uniform magnitude.

7. The method of claim 3 wherein the increments are of variable magnitude.

8. The method of claim 7 wherein the increments are varied as a function of the magnitude of the speed change detected from at least one prior increment.

9. The method of claim 3 comprising, providing a calibrated peak power condition and wherein the offset value is used to control the air-fuel mixture ratio delivered to the engine as a function of the difference between the actual measured peak power condition and the calibrated peak power condition.

10. A method of operating an engine, comprising:

(a) providing a relatively rich fuel and air mixture to the engine;

(b) enleaning the fuel and air mixture;

(c) sensing a change in an engine parameter that occurred after said enleaning step;

(d) determining a peak power condition of the engine based on changes in said engine parameter;

(e) determining the temperature of the engine exhaust gas at the peak power condition;

(f) comparing the exhaust gas temperature measured in step (e) with a previously determined exhaust gas temperature associated with a peak power condition of the engine;

(g) determining an offset value based on the comparison made in step (f); and

(h) controlling at least one engine controllable factor as a function of the offset value.

11. The method of claim 10 wherein the engine parameter is engine speed.

12. The method of claim 10 wherein the engine controllable factor includes an air-fuel ratio delivered to the engine.

13. The method of claim 10 wherein the engine controllable factor includes ignition timing.

14. The method of claim 10 wherein step (a) of the method is accomplished by providing the relatively rich fuel and air mixture to the engine through a fuel and air mixing passage of a carburetor;

and wherein step (b) of the method includes providing a control signal to a solenoid valve through which fuel or air flows to the mixing passage to enlean the fuel and air mixture to the engine.

15. The method of claim 10 wherein step (b) is accomplished by applying a subatmospheric pressure to a float bowl of a carburetor supplying a fuel and air mixture to the engine by actuating a solenoid valve to selectively communicate a subatmospheric pressure source with the float bowl to alter the air-fuel mixture ratio delivered from the carburetor to the engine.

16. The method of claim 15 wherein the subatmospheric pressure source is a fuel and air mixing passage of the carburetor.

17. The method of claim 10 wherein step (b) is accomplished by applying a subatmospheric pressure to a diaphragm of a fuel metering chamber from which fuel flows into a fuel and air mixing passage of a carburetor by actuating a solenoid valve to selectively communicate a subatmospheric pressure source with the diaphragm to alter the air-fuel mixture ratio delivered from the carburetor to the engine.

18. The method of claim 17 wherein the subatmospheric pressure source is the fuel and air mixing passage of the carburetor.

19. The method of claim 10 wherein the measured temperature associated with the engine is exhaust gas temperature.