Engine demand fuel delivery system

• US 5,740,783 A
• Filed: 11/15/1996
• Issued: 04/21/1998
• Est. Priority Date: 12/30/1994
• Status: Expired due to Term

• Current Assignee: Walbro Engine Management LLC (Sun Capital Partners Incorporated)
• Original Assignee: Walbro Corporation (Sun Capital Partners Incorporated)
• Inventors: Learman, William L., Werner, Matthew L., Roche, Ronald H.
• Primary Examiner(s): MILLER, CARL STUART
• Application Number:
  US08/749,448
• Time in Patent Office: 522 Days
• Field of Search: 123/497, 123/456, 123/359, 123/357, 123/358
• US Class Current: 123/497
• CPC Class Codes: F02D 41/3082 Control of electrical fuel pumps
• CPC Class Codes: F02M 2037/085 Electric circuits therefor
• CPC Class Codes: F02M 37/08 electrically driven

Abstract

A fuel delivery system and method for providing fuel to a fuel injected engine using an engine control unit (ECU) to determine engine fuel demand and adjust fuel pump operation accordingly to supply at least as much fuel as demanded by the engine. The ECU determines a fuel pump control signal based upon fuel demand and applies the signal to a fuel pump driver that controllably drives the pump in response to the control signal. The ECU determines fuel demand by monitoring engine operation and calculates a control signal that controls the duration of time the fuel injector stays open during an upcoming intake stroke of engine operation. The pump control signal is proportional to engine fuel demand multiplied by a constant that ensures more fuel will be available for delivery to the injector than demanded by the engine. Engine fuel demand is proportional to the duration of time the injector will stay open multiplied by the engine speed. Preferably, if the calculated pump signal is less than a minimum that would cause the pump to operate below a desired minimum duty cycle, the control signal is set at the minimum to ensure sufficient excess fuel will be available to meet any sharp increases in demand. If the calculated signal is greater than the maximum pump duty cycle, the signal is set at the maximum to avoid damaging the pump. If the calculated signal is between the minimum and maximum limits, the control signal is set to the calculated value.

Claims

1. A fuel delivery system for a spark ignited internal combustion engine having a fuel injector for dispensing fuel into a cylinder of the engine comprising:

a fuel supply;

an electric fuel pump in fluid flow communication with said fuel supply and responsive to application of electrical energy for delivery of fuel from said fuel supply to the injector of the internal combustion engine;

a pressure regulator in communication with the fuel pump and the injector for supplying fuel to the injector at a substantially constant pressure;

an engine spark ignition system for igniting fuel in the engine cylinder;

an engine electronic control unit;

a device driven by the engine and producing an electric current to power the engine spark ignition system, engine electronic control unit, fuel injector and the electric fuel pump system with the electric current produced by the device during engine startup and idle conditions having insufficient electric power to meet all of these electric power requirements if the electric pump were operated at a preselected maximum duty cycle to deliver a maximum quantity of fuel sufficient to meet the engine maximum fuel consumption demands;

a first sensor of the speed of rotation of the engine;

a second sensor of one of air intake throttle opening position and mass flow rate of intake air entering the engine; and

the engine electronic control unit being in communication with the first and second sensors and having first means determining the anticipated engine fuel demand for each injector before it delivers fuel to the engine and for supplying a first control signal to said fuel pump for varying and regulating the quantity of fuel said pump makes available to the fuel injector as a function of and proportional to the quantity of fuel the first means anticipates will be consumed by the engine between a preselected minimum quantity of fuel sufficient for operation of the engine under idle conditions and a preselected maximum quantity of fuel which prevents damage to the electric fuel pump by not exceeding its maximum duty cycle, second means producing a second control signal to control the amount of time each fuel injector stays open for supplying fuel to the engine, and for each fuel intake cycle of each cylinder of the engine the electronic control unit applies the first control signal to the fuel pump at least by the time it applies its associated second control signal to its associated fuel injector to deliver only slightly more fuel than is used by the fuel injector and minimize the electric power required to operate the electric fuel pump at startup, idle and low engine speeds.

2. The fuel delivery system of claim 1 also comprising a fuel pump driver in communication with said engine control unit and in communication with said fuel pump for supplying electrical energy to said fuel pump to power said fuel pump in response to communication by said fuel pump driver with said engine control unit.

3. The fuel delivery system of claim 2 wherein said fuel pump driver is an electrical circuit responsive to a control signal for outputting electrical energy to said fuel pump proportional to said control signal for varying fuel output from said fuel pump in proportion to said control signal and said engine control unit generates said control signal and communicates said control signal to said fuel pump driver for varying and regulating fuel pump operation to make at least as much fuel available to the fuel injector as will be consumed by the engine.

4. The fuel delivery system of claim 3 wherein said control signal generated by said engine control unit is proportional to engine fuel demand determined by said engine control unit.

5. The fuel delivery system of claim 4 wherein said control signal generated by said engine control unit is proportional to engine fuel demand determined by said engine control unit and causes said fuel pump to supply at least five percent more fuel to the injector than demanded by the engine for at least replacing fuel that will be consumed by the engine while supplying adequate fuel to maintain fuel pressure at the injector.

6. The fuel delivery system of claim 4 wherein said engine control unit senses the amount of air entering the engine and senses engine speed for determining engine fuel demand.

7. The fuel delivery system of claim 6 wherein said engine control unit senses engine throttle position and senses engine speed for determining engine fuel demand.

8. The fuel delivery system of claim 6 wherein said engine control unit senses mass airflow of air entering the engine and senses engine speed for determining engine fuel demand.

9. The fuel delivery system of claim 4 wherein said engine control unit determines engine fuel demand by determining how much fuel will be dispensed by the fuel injector during a fixed period of time of engine operation.

10. The fuel delivery system of claim 9 wherein the fuel injector opens for a duration of time during each intake stroke of its cylinder during engine operation for dispensing fuel into the cylinder and said engine control unit determines fuel demand of the engine by multiplying the duration of time the injector will dispense fuel into the engine cylinder during the next intake stroke by the speed of the engine.

11. The fuel delivery system of claim 10 wherein said control signal generated by said engine control unit is proportional to the duration of time the injector will dispense fuel into the engine cylinder during the next intake stroke multiplied by the speed of the engine for varying and regulating fuel pump operation to make at least as much fuel available to the fuel injector as will be consumed by the engine.

12. The fuel delivery system of claim 10 wherein said control signal generated by said engine control unit is proportional to the duration of time the injector will dispense fuel into the engine cylinder during the next intake stroke multiplied by the speed of the engine and multiplied by a constant to ensure that said fuel pump supplies more fuel than demanded by the engine for at least replacing fuel that will be consumed by the engine while supplying adequate fuel to maintain fuel pressure at the injector.

13. The fuel delivery system of claim 12 wherein said constant is determined by calibrating the fuel delivery system by monitoring fuel flow to the engine and varying the value of said constant until said control signal causes said fuel pump to deliver a desired amount of fuel to the injector in excess of that demanded by the engine to at least replace fuel consumed by the engine while maintaining adequate fuel pressure at the injector.

14. The fuel delivery system of claim 12 wherein said constant is chosen so that said fuel pump delivers at least five percent more fuel to the injector than engine fuel demand.

15. The fuel delivery system of claim 3 wherein said electrical energy applied by said fuel pump driver to said fuel pump is an electrical duty cycle signal for controlling the amount of energy applied to said fuel pump during a fixed period of time of fuel pump operation to controllably vary fuel flow from said pump to the fuel injector in proportion to said electrical duty cycle signal from said fuel pump driver and said control signal generated by said engine control unit is compared with a minimum fuel pump operating capacity value and said control signal is set equal to said minimum fuel pump operating capacity value if said generated control signal is less than said minimum value so that said fuel pump driver provides a minimum duty cycle signal to said fuel pump to ensure said fuel pump always delivers a predetermined minimum amount of fuel flow to the fuel injector.

16. The fuel delivery system of claim 15 wherein said control signal generated by said engine control unit is compared with a maximum pump operating capacity value and setting said control signal equal to said maximum pump operating capacity value if said control signal is greater than said maximum value so that said fuel pump driver provides a corresponding maximum duty cycle signal to said fuel pump to ensure said fuel pump never delivers more than a predetermined maximum amount of fuel flow to the fuel injector.

17. The fuel delivery system of claim 16 wherein said minimum pump operating capacity value is that which produces a control signal to said fuel pump driver for providing at least a twenty percent duty cycle signal to said fuel pump so that said fuel pump never operates at less than twenty percent of its fuel pumping capacity.

18. The fuel delivery system of claim 17 wherein said minimum pump operating capacity value is that which produces a control signal to said fuel pump driver for providing a fifty percent duty cycle signal to said fuel pump so that said fuel pump never operates at less than fifty percent of its fuel pumping capacity.

19. The fuel delivery system of claim 16 wherein said maximum control signal is an electrical control signal which causes said fuel pump driver to provide a one-hundred percent duty cycle signal to said fuel pump so that said fuel pump never operates at more than one-hundred percent of its fuel pumping capacity.

20. The fuel delivery system of claim 15 wherein said fuel pump includes a direct current pump motor and wherein said fuel pump driver comprises a pulse width modulation amplifier for applying a pulsed direct current electrical signal to said fuel pump motor at a duty cycle that varies relative to said control signal provided by said engine control unit to vary said duty cycle as a function of engine fuel demand.

21. The fuel delivery system of claim 1 also comprising a fuel pump driver in communication with said engine control unit and in communication with said fuel pump for supplying electrical energy to said fuel pump to power said fuel pump in response to communication by said fuel pump driver with said engine control unit and a module for receiving said engine control unit and said fuel injector driver.

22. The fuel delivery system of claim 21 wherein said engine control unit is integral with said fuel pump driver.

23. The fuel delivery system of claim 22 wherein said engine control unit and said fuel pump driver are on the same circuit board.

24. The fuel delivery system of claim 1 also comprising a fuel pump driver in communication with said engine control unit and in communication with said fuel pump for supplying electrical energy to said fuel pump to power said fuel pump in response to communication by said fuel pump driver with said engine control unit and said fuel pump driver being in close proximity to said fuel pump for minimizing the distance said electrical energy must travel to said fuel pump.

25. The fuel delivery system of claim 24 wherein said fuel pump driver is carried on said fuel pump.

26. The fuel delivery system of claim 1 also comprising a fuel pump driver in communication with said engine control unit and in communication with said fuel pump for supplying electrical energy to said fuel pump to power said fuel pump in response to communication by said fuel pump driver with said engine control unit and wherein said fuel pump driver is an electrical circuit responsive to a fuel pump control signal for outputting electrical energy to said fuel pump proportional to said fuel pump control signal for varying fuel output from said fuel pump in proportion to said fuel pump control signal and said engine control unit generates said fuel pump control signal proportional to:

space="preserve" listing-type="equation">Fuel Pump Control Signal≃

(Engine Speed)*(Fuel Duration)*K

and said engine control unit communicates said fuel pump control signal to said fuel pump driver for varying and regulating fuel pump operation to make at least as much fuel available to the fuel injector as will be consumed by the engine.

27. The fuel delivery system of claim 1 wherein between the minimum and maximum quantity of fuel the first means and first control signal causes the fuel pump to actually deliver a quantity of fuel which is not more than about 10% greater than the actual fuel demand of the engine.

29. The fuel delivery system of claim 1 wherein the engine spark ignition system, engine electronic control unit and electric fuel pump are not connected to an electric storage battery.

28. A fuel delivery system for a spark ignited internal combustion engine having a fuel injector for dispensing fuel into a cylinder of the engine comprising;

a fuel supply;

an electric fuel pump in fuel flow communication with said fuel supply and responsive to application of electric energy for delivery of fuel from said fuel supply to the injector of the internal combustion engine;

an engine spark ignition system for igniting fuel in the engine cylinder;

a pressure regulator in communication with the fuel pump and the injector for supplying fuel to the injector at a substantially constant pressure;

a device driven by the engine and producing an electric current at startup, idle and low engine speeds having insufficient power to meet the power requirements of all of the spark ignition system, fuel injector and the electric fuel pump if operated at a maximum duty cycle to deliver a maximum quantity of fuel;

a first sensor of the speed of rotation of the engine;

a second sensor of one of air intake throttle opening position and mass flow rate of intake air entering the engine; and

an engine electronic control unit in communication with the first and second sensors and having first means determining the anticipated engine fuel demand for each injector before it delivers fuel to the engine and for supplying a first control signal to said electric fuel pump for varying and regulating the quantity of fuel said pump makes available to the fuel injector as a function of and proportional to the quantity of fuel the first means anticipated will be consumed by the engine between a preselected minimum quantity of fuel sufficient for operation of the engine under startup, idle and low engine speed conditions and a preselected maximum quantity of fuel which prevents damage to the electric fuel pump by not exceeding its maximum duty cycle, second means producing a second control signal to control the amount of time each fuel injector stays open for supplying fuel to the engine, and for each fuel intake cycle of each cylinder of the engine the electronic control unit applies the first control signal to the fuel pump at least by the time it applies its associated second control signal to its associated fuel injector to deliver only slightly more fuel than is used by the fuel injector and minimize the electric power required to operate the electric fuel pump at startup, idle and low engine speeds.

30. The fuel delivery system of claim 28 wherein the engine spark ignition system, engine electronic control unit and electric fuel pump are not connected to an electric storage battery.