Optimizing intermittent fuel pump control

• US 10,094,319 B2
• Filed: 12/02/2014
• Issued: 10/09/2018
• Est. Priority Date: 12/02/2014
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Ulrey, Joseph Norman, Pursifull, Ross Dykstra
• Primary Examiner(s): Huynh, Hai
• Assistant Examiner(s): Laguarda, Gonzalo
• Application Number:
  US14/558,363
• Publication Number:
  US 20160153383A1
• Time in Patent Office: 1,407 Days
• Field of Search: 123458
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02D 33/003 Controlling the feeding of liquid fuel from storage containers to carburettors or fuel-injection apparatus control of electrical fuel pumps F02D41/3082, controlling fuel flow to a common rail F02D41/3845; Failure or leakage prevention; Diagnosis or detection of failure; Arrangement of sensors in the fuel system; Electric wiring; Electrostatic discharge
• CPC Class Codes: F02D 41/2464 Characteristics of actuators
• CPC Class Codes: F02D 41/3082 Control of electrical fuel pumps
• CPC Class Codes: F02D 41/3854 with elements in the low pressure part, e.g. low pressure pump
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 37/0058 Returnless fuel systems, i.e. the fuel return lines are not entering the fuel tank
• CPC Class Codes: F02M 59/366 Valves being actuated electrically

Abstract

Various methods are provided for operating a fuel pump. In one example, a method of operating a fuel pump comprises iteratively reducing an on-duration of a low pressure fuel pump pulse, until a peak outlet pressure of the fuel pump decreases from a peak outlet pressure corresponding to a previous pulse, to identify a minimum pulse duration, and applying a pulse having the minimum pulse duration to the fuel pump.

Claims

1. A method of operating a fuel pump, comprising:

during intermittent fuel pump operation including a plurality of voltage pulses being applied to the fuel pump where a speed of the fuel pump falls to zero between voltage pulses;

iteratively reducing an on-duration of each voltage pulse, until a peak outlet pressure of the fuel pump decreases from a peak outlet pressure corresponding to a previous voltage pulse, to identify a minimum pulse duration; and

applying a voltage pulse having the minimum pulse duration to the fuel pump; and

during continuous fuel pump operation including a plurality of voltage pulses being applied to the fuel pump where the fuel pump turns continuously without stopping between voltage pulses;

applying a varying duty cycle to the fuel pump.

2. The method of claim 1, wherein applying the voltage pulse having the minimum pulse duration to the fuel pump causes the fuel pump to pump a desired fuel volume, and wherein the fuel pump supplies fuel to an accumulator downstream of the fuel pump.

3. The method of claim 1, wherein the on-duration of each voltage pulse is iteratively reduced until a duration for which the fuel pump outputs the peak outlet pressure falls below a threshold.

4. The method of claim 1, wherein applying the voltage pulse having the minimum pulse duration to the fuel pump comprises applying voltage pulses having the minimum pulse duration to the fuel pump while one or both of an engine load and an engine speed are below respective thresholds, and wherein intermittent fuel pump operation comprises alternating pump-on periods and pump-off periods, the on-duration being a duration of the pump-on periods.

5. The method of claim 4, wherein the continuous fuel pump operation occurs while one or both of the engine load and the engine speed are equal to or above the respective thresholds, and wherein a speed of the fuel pump falls to zero during the pump-off periods.

6. The method of claim 1, wherein the voltage pulse having the minimum pulse duration is applied to the fuel pump responsive to an outlet pressure of the fuel pump falling to a lower threshold pressure, wherein the duty cycle is based on an engine speed and an engine load, and wherein a speed of the fuel pump falls to zero during pump-off periods.

7. The method of claim 1, wherein the voltage pulse having the minimum pulse duration is applied to the fuel pump responsive to a fuel volume being pumped by a high-pressure fuel pump disposed downstream of the fuel pump.

8. The method of claim 7, wherein the fuel pump is a lift pump, and wherein the fuel volume is less than a desired fuel volume, that when pumped by the lift pump, causes an inlet pressure of the high-pressure fuel pump to fall substantially to a fuel vapor pressure.

9. The method of claim 1, further comprising:

associating the minimum pulse duration with a fuel temperature; and

storing the minimum pulse duration associated with the fuel temperature in a data structure comprising a plurality of minimum pulse durations each associated with a respective fuel temperature.

10. The method of claim 1, wherein the on-duration is iteratively reduced responsive to a threshold change in fuel temperature.

11. A method of operating a fuel pump, comprising:

under first conditions,

driving the fuel pump intermittently by applying a voltage pulse two or more times; and

iteratively reducing a duration of each voltage pulse until a fuel volume pumped resulting from application of the reduced voltage pulse is reduced to identify a minimum duration; and

under second conditions,

driving the fuel pump intermittently with a voltage pulse lasting the minimum duration,

wherein driving the fuel pump intermittently comprises repeatedly applying the voltage pulse to the fuel pump, where each voltage pulse is spaced apart from an adjacent voltage pulse by an inter-pulse duration in which the fuel pump is off and a speed of the fuel pump falls to zero.

12. The method of claim 11, further comprising:

under the first conditions,

driving the fuel pump with the voltage pulse lasting the minimum duration two or more times;

correlating a fuel volume pumped with each application of the voltage pulse lasting the minimum duration; and

identifying an inter-pulse fuel volume less than a desired fuel volume; and

under the second conditions,

driving the fuel pump with the voltage pulse lasting the minimum duration upon pumping of the inter-pulse fuel volume.

13. The method of claim 12, wherein driving the fuel pump with the voltage pulse lasting the minimum duration upon pumping of the inter-pulse fuel volume maintains an outlet pressure of the fuel pump above a fuel vapor pressure.

14. The method of claim 11, wherein, before the fuel volume is reduced, a fuel volume pumped resulting from application of the voltage pulse is a desired fuel volume at each reduced iteration.

15. The method of claim 11, wherein the first conditions include occurrence of a threshold change in fuel temperature, and further comprising, when an engine speed or an engine load is above a respective threshold, continuously operating the fuel pump by applying a duty cycle to the fuel pump, said duty cycle based on the engine speed and the engine load, and where continuously operating the fuel pump includes applying a plurality of voltage pulses to the fuel pump where the fuel pump turns continuously without stopping between voltage pulses.

16. The method of claim 11, wherein the second conditions include one or both of engine speed and engine load being below respective thresholds, and wherein the fuel pump is a lift pump delivering fuel to an accumulator disposed between the lift pump and a downstream high-pressure fuel pump.

17. A method of operating a fuel pump, comprising:

during a first condition;

iteratively reducing an on-duration of a fuel pump pulse, until an outlet pressure of the fuel pump remains at a peak outlet pressure for less than a threshold duration, to identify a desired pulse duration, wherein the fuel pump is pumping fuel during the pulse;

repeatedly applying the pulse for the desired pulse duration to the fuel pump responsive to a fueling condition, wherein each pulse is spaced apart from successive pulses by an inter-pulse duration; and

adjusting the inter-pulse duration between successive pulses based on a minimum value of pumped fuel for the repeated application of the pulses for the desired pulse duration, wherein a speed of the fuel pump falls to zero during the inter-pulse duration; and

during a second condition;

continuously applying a duty cycle to the fuel pump, the duty cycle based on an engine speed and an engine load.

18. The method of claim 17, wherein application of the pulse for the desired pulse duration results in pumping of a desired value of pumped fuel,

wherein the minimum value of pumped fuel is less than the desired value of pumped fuel, and

wherein the first condition includes the engine speed or the engine load being below respective thresholds, and wherein the second condition includes the engine speed or the engine load being above the respective thresholds.

19. The method of claim 18, further comprising storing the desired pulse duration and the desired value of pumped fuel as a function of fuel temperature, and wherein the fuel pump is a lift pump disposed upstream of a high-pressure fuel pump.

20. The method of claim 17, wherein the fueling condition includes pumping of a desired value of pumped fuel, and wherein the fuel pump delivers fuel to an accumulator disposed downstream of the fuel pump.