SYSTEMS AND METHODS FOR SENSING FUEL VAPOR PRESSURE

• US 20160153384A1
• Filed: 12/02/2014
• Published: 06/02/2016
• 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, Kumar, Pankaj, Makki, Imad Hassan
• Granted Patent: US 9,726,105 B2
• Time in Patent Office: Days
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2200/0604 Estimation of fuel pressure
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02D 2200/0612 determined by estimation
• CPC Class Codes: F02D 2250/02 Fuel evaporation in fuel rails, e.g. in common rails
• CPC Class Codes: F02D 2250/04 Fuel pressure pulsation in common rails
• CPC Class Codes: F02D 41/064 at cold start F02D41/067 takes precedence
• 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

Abstract

Systems and methods for sensing fuel vapor pressure are provided. In one example, a method for a vehicle comprises: during an engine start after the engine has been off for at least a minimum duration, actively controlling fuel pressure in the fuel system to a vapor-liquid volume ratio greater than zero and then recording sensed fuel pressure and temperature in the fuel system. In this way, the vapor pressure of a fuel at a given temperature may be accurately measured during isothermal conditions, thereby improving an estimation of fuel volatility.

Claims

1. A method for a vehicle, comprising:

during an engine start after the engine has been off for at least a minimum duration, actively controlling fuel pressure in a fuel system to a vapor-liquid volume ratio greater than zero and then recording sensed fuel pressure and temperature in the fuel system.

2. The method of claim 1, wherein actively controlling the fuel pressure comprises pulsing a fuel pump.

3. The method of claim 1, wherein recording the sensed fuel pressure and temperature is performed responsive to a detection of fuel vapor.

4. The method of claim 3, wherein the detection of fuel vapor comprises sensing a decrease in volumetric efficiency of the fuel pump.

5. The method of claim 3, further comprising actively controlling the fuel pressure after recording and in response to the sensed fuel pressure and temperature.

6. The method of claim 1, further comprising determining fuel volatility based on the recorded sensed fuel pressure and temperature, and adjusting engine operation during subsequent engine combustion conditions based on the determined fuel volatility via an engine controller.

7. The method of claim 1, further comprising determining fuel composition based on the recorded sensed fuel pressure and temperature, and adjusting engine operation during subsequent engine combustion conditions based on the determined fuel composition via an engine controller.

8. The method of claim 1, wherein recording the sensed fuel temperature comprises recording a sensed temperature comprising at least one of a fuel system temperature, turbine outlet temperature, engine coolant temperature, air charge temperature, manifold charging temperature, throttle charge temperature, cylinder head temperature, ambient air temperature, engine oil temperature, and fuel rail temperature.

9. A fuel system for an engine, comprising:

a fuel tank containing fuel;

a fuel pump positioned within the fuel tank and configured to pump the fuel to one or more fuel injectors coupled to the engine;

a temperature sensor coupled to a fuel passage connecting the fuel pump to the one or more fuel injectors;

a pressure sensor coupled to the fuel passage;

a controller configured with instructions stored in non-transitory memory, that when executed, cause the controller to;

actively control fuel pressure in the fuel passage during an engine start after the engine has been off for at least a minimum duration; and

record a sensed temperature from the temperature sensor and a sensed pressure from the pressure sensor.

10. The fuel system of claim 9, wherein actively controlling the fuel pressure comprises pulsing the fuel pump to drive the fuel pressure to a vapor-liquid volume ratio greater than zero.

11. The fuel system of claim 10, wherein the fuel pump is pulsed responsive to a detection of fuel vapor.

12. The fuel system of claim 11, wherein the detection of fuel vapor comprises sensing a decrease in volumetric efficiency of the fuel pump.

13. The fuel system of claim 9, wherein the controller is further configured with instructions that when executed cause the controller to calculate a fuel volatility based on the recorded temperature and the recorded pressure.

14. The fuel system of claim 9, wherein the controller is further configured with instructions that when executed cause the controller to determine a fuel composition based on the recorded temperature and the recorded pressure.

15. The fuel system of claim 9, wherein the controller is further configured with instructions that when executed cause the controller to update one or more control routines based on the recorded temperature and the recorded pressure.

16. A method, comprising:

pulsing a fuel pump responsive to an engine cold start; and

determining a fuel vapor pressure versus temperature characteristic based on fuel pressure and temperature while the fuel pump is being pulsed in response to a reduction in DI pump volumetric efficiency.

17. The method of claim 16, wherein a duration of pulsing the fuel pump is based on a temperature sensed prior to pulsing, the method further comprising, via an engine controller, adjusting engine fuel injection based on the determined fuel vapor pressure versus temperature characteristic during engine combustion operation, the engine controller further pulsing the fuel pump and including instructions to determine the fuel vapor pressure versus temperature characteristic based on sensed fuel pressure and temperature.

18. The method of claim 16, wherein a duty cycle of pulsing the fuel pump is adjusted based on a temperature sensed immediately prior to pulsing.

19. The method of claim 16, further comprising determining a fuel volatility based on the fuel vapor pressure versus temperature characteristic.

20. The method of claim 16, wherein the engine cold start comprises an engine turning on after the engine has been off for at least a minimum duration.