ENGINE FUEL DELIVERY SYSTEMS, APPARATUS AND METHODS

• US 20100258099A1
• Filed: 10/27/2008
• Published: 10/14/2010
• Est. Priority Date: 10/27/2007
• Status: Active Grant

• Current Assignee: Walbro LLC
• Original Assignee: Walbro Engine Management LLC (Sun Capital Partners Incorporated)
• Inventors: Casoni, Massimo, Swanson, Mark S., Roche, Ronald H., Healy, Cyrus M., Van Allen, James E., Pascoli, Alessandro, Bejcek, Andrew E., Galka, William E., Andersson, Martin N., Woody, John C.
• Granted Patent: US 9,022,011 B2
• Time in Patent Office: Days
• 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;

(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);

(e) controlling at least one of an air-fuel mixture delivered to the engine or ignition spark timing 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) is accomplished by altering, in more than one increment, 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.

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 2 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);

(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. A carburetor, comprising:

a carburetor body including an air and fuel mixing passage, a valve rotatably disposed in the mixing passage; and

a control module carried on the carburetor body and including a circuit board and a rotary position sensor carried on the circuit board and cooperating with a portion of the valve to sense rotary position of the valve.

15. A carburetor, comprising:

a body including a fuel and air mixing passage;

a solenoid associated with the body and with one or more control passages through which fuel or air flow, the solenoid including a valve that may be opened to permit communication between two or more passages and may be closed to prevent communication between said two or more passages, wherein the solenoid is responsive to a control signal to selectively permit communication between said two or more passages to alter an air-fuel mixture ratio delivered from the carburetor.

16. The carburetor of claim 15 which also includes a float bowl carried by the body and including a supply of fuel, and wherein said two or more passages include one passage communicated with a subatmospheric pressure source and a second passage communicated with the float bowl such that the solenoid selectively communicates said one passage with said second passage to selectively communicate the subatmospheric pressure source with the float bowl to alter the air-fuel mixture ratio delivered from the carburetor.

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

18. The carburetor of claim 15 which also includes a fuel metering assembly including a diaphragm carried by the body and a fuel metering chamber from which fuel flows into the fuel and air mixing passage, and wherein said two or more passages include one passage communicated with a subatmospheric pressure source and a second passage communicated with the fuel metering chamber such that the solenoid selectively communicates said one passage with said second passage to selectively communicate the subatmospheric pressure source with the fuel metering chamber to alter the air-fuel mixture ratio delivered from the carburetor.

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

20. An electronic control system for use with a light-duty internal combustion engine, comprising:

a control module; and

a power generation unit having a charge circuit with a charge capacitor and a discharge circuit with a discharge switch, and the discharge switch is coupled to the charge capacitor and causes ignition of the light-duty internal combustion engine by its operation;

wherein the power generation unit controls the discharge switch during a first engine sequence and the control module controls the discharge switch during a second engine sequence.

21. The electronic control system of claim 20, wherein the control module and the power generation unit are physically separated from one another.

22. The electronic control system of claim 21, wherein the control module includes a rotary position sensor and is located near a carburetor of the light-duty internal combustion engine, and the rotary position sensor senses the position of a rotating shaft that extends from the carburetor to the control module.

23. The electronic control system of claim 22, wherein the rotary position sensor includes a plurality of magnetoresistive (MR) elements arranged as a pair of angularly offset resistive bridges, and the rotary position sensor is mounted to a circuit board of the control module and magnetically interacts with a magnetic element fixed to the rotating shaft.

24. The electronic control system of claim 23, wherein the rotary position sensor is mounted to the circuit board of the control module so that:

i) a surface of the rotary position sensor is generally parallel to a rotating magnetic field caused by the magnet, ii) the rotary position sensor is not coplanar with the magnet, and iii) the rotary position sensor is not coaxial with the rotating shaft.

25. The electronic control system of claim 23, wherein the control module further includes an amplifier that is coupled to one of the resistive bridges and includes a voltage divider and an operational amplifier, and the voltage divider is connected between the resistive bridge and an input to the operational amplifier and provides a voltage offset.

26. The electronic control system of claim 23, wherein the control module further includes an amplifier that is coupled to one of the resistive bridges and includes a feedback loop and an operational amplifier, and the feedback loop includes a plurality of resistors that have the same resistance and are connected between an output and an input of the operational amplifier.

27. The electronic control system of claim 21, wherein the power generation unit is located near a flywheel of the light-duty internal combustion engine.

28. The electronic control system of claim 27, wherein the charge circuit of the power generation unit further includes a charge winding that electromagnetically interacts with magnetic elements of the flywheel, and the charge winding provides the charge capacitor with energy having a first polarity and provides a power capacitor with energy having a second polarity.

29. The electronic control system of claim 21, wherein the discharge circuit of the power generation unit is generally analog and includes a first sub-circuit that enables the power generation unit to control the discharge switch during the first engine sequence, and a second sub-circuit that enables the control module to control the discharge switch during the second engine sequence.

30. The electronic control system of claim 29, wherein the first sub-circuit includes a trigger coil that electromagnetically interacts with magnetic elements of the flywheel and operates the discharge switch during the first engine sequence.

31. The electronic control system of claim 29, wherein the second sub-circuit includes a signal input that is coupled to the control module and operates the discharge switch during the second engine sequence according to a signal from the control module.

32. The electronic control system of claim 31, wherein the second sub-circuit further includes a first switch, a second switch, and an RC circuit, and the signal from the control module causes:

i) the first switch to short a trigger coil so that it cannot operate the discharge switch, ii) the second switch to operate the discharge switch, and iii) the RC circuit to influence the timing of at least one of the first and second switches.

33. The electronic control system of claim 21, wherein the discharge circuit of the power generation unit is generally digital and includes a digital processing unit that is coupled to an engine speed sensor, the control module, and the discharge switch, and the digital processing unit enables the power generation unit to control the discharge switch during the first engine sequence and enables the control module to control the discharge switch during the second engine sequence.

34. The electronic control system of claim 33, wherein the digital processing unit uses engine speed information gathered independently of the control module to control the discharge switch during the first engine sequence.

35. The electronic control system of claim 33, wherein the digital processing unit is coupled to a switching device that is connected between the charge winding and the charge capacitor, and the digital processing unit operates the switching device so that it shorts the charge winding during a charge process.

36. The electronic control system of claim 20, wherein the power generation unit controls the discharge switch during the first engine sequence which occurs when there is insufficient power to the operate the control module, and the control module controls the discharge switch during the second engine sequence which occurs when there is sufficient power to operate the control module.

37. The electronic control system of claim 36, wherein the first engine sequence occurs immediately following engine start up, and the second engine sequence occurs immediately following the first engine sequence.

38. The electronic control system of claim 20, further comprising a limp-home feature so that a failure in the control module during the second engine sequence causes the power generation unit to take control of the discharge switch.