Systems and methods for inferring barometric pressure

Patent metadata

Field	Value
Publication number	US-2018171902-A1
Application number	US-201815894224-A
Country	US
Kind code	A1
Filing date	Feb 12, 2018
Priority date	Jul 15, 2016
Publication date	Jun 21, 2018
Grant date	—

Abstract

Methods and systems are provided for determining barometric pressure. In one example, an onboard vacuum pump is utilized to draw a vacuum at a constant flow rate across a reference orifice, and the resulting vacuum level is converted to a barometric pressure. In this way, other sensors for determining barometric pressure in a vehicle may be rationalized without the use of engine operation, and in an example where the other sensors for determining barometric pressure are not functioning as desired, barometric pressure as inferred from the onboard pump may be utilized to adjust engine operation.

First claim

1 . A method for operating a hybrid-electric vehicle, comprising:
driving vehicle wheels with an electric motor; delivering fuel from a fuel system to an engine propelling the vehicle wheels; storing fuel vapors from the fuel system in an evaporative emissions control system; determining an estimate of barometric pressure as a function of an efficiency of a vacuum pump configured to evacuate or pressurize the fuel system and evaporative emissions control system; and adjusting a vehicle operating parameter responsive to the estimate.

2 . The method of claim 1 , wherein the vehicle is a plug-in hybrid-electric vehicle.

3 . The method of claim 1 , wherein the fuel system has a fuel cap with a fuel cap locking mechanism configured to automatically lock the fuel cap in a closed position, the fuel cap remaining locked via a refueling lock while pressure or vacuum in a fuel tank of the fuel system is greater than a threshold, the method further comprising, in response to a refuel request by an operator, depressurizing the fuel tank and then unlocking the fuel cap unlocked after the pressure or vacuum in the fuel tank falls.

4 . The method of claim 1 , further comprising:
turning on the vacuum pump and drawing a vacuum across a reference orifice of fixed diameter, wherein drawing the vacuum across the reference orifice of fixed diameter includes configuring a changeover valve coupled to the vacuum pump in a first position; and wherein pressurizing or evacuating the vehicle fuel system and evaporative emissions control system includes configuring the changeover valve in a second position.

5 . The method of claim 4 , wherein the efficiency of the vacuum pump is a function of a vacuum level achieved by the vacuum pump when drawing the vacuum across the reference orifice of fixed diameter.

6 . The method of claim 1 , wherein efficiency of the vacuum pump decreases as barometric pressure decreases; and wherein
the efficiency of the vacuum pump increases as barometric pressure increases.

7 . The method of claim 1 , further comprising:
correlating barometric pressure determined as the function of the efficiency of the vacuum pump with barometric pressure determined from one or more sensor(s) in the vehicle, and indicating the one or more sensor(s) in the vehicle are not functioning as desired responsive to a lack of correlation between barometric pressure determined as the function of the efficiency of the vacuum pump and barometric pressure determined from the one or more sensor(s) in the vehicle.

8 . The method of claim 7 , wherein the one or more sensor(s) in the vehicle include a manifold absolute pressure sensor coupled to an air intake manifold of the engine.

9 . The method of claim 1 , wherein adjusting a vehicle operating parameter responsive to the estimate includes adjusting an open-loop throttle position of a throttle coupled to an air intake manifold of the engine to a more closed position responsive to an increase in barometric pressure, and adjusting the open-loop throttle position to a more open position responsive to a decrease in barometric pressure.

10 . The method of claim 1 , wherein adjusting a vehicle operating parameter responsive to the estimate includes adjusting timing of a spark provided to one or more engine cylinder(s);
wherein adjusting timing of the spark includes more aggressive spark timing responsive to barometric pressure increase, and less aggressive spark timing responsive to barometric pressure decrease.

11 . The method of claim 1 , wherein adjusting a vehicle operating parameter responsive to the estimate further comprises adjusting an evaporative emissions test diagnostic threshold.

12 . The method of claim 1 , wherein the estimate of barometric pressure is determined without operation of the vehicle engine but while the vehicle operates in an electric mode.

13 . A method of operating a hybrid-electric vehicle, comprising:
driving vehicle wheels with an electric motor via stored electrical energy; indicating barometric pressure via one or more barometric pressure sensor(s) positioned in the vehicle; activating a vacuum pump onboard the vehicle to draw a vacuum across a reference orifice of fixed diameter; determining barometric pressure as a function of a vacuum level reached during activating the onboard vacuum pump; and indicating the one or more vehicle barometric pressure sensor(s) are not functioning as desired responsive to barometric pressure determined as the function of the vacuum level reached during activating the onboard vacuum pump not correlating with barometric pressure indicated via the one or more barometric pressure sensor(s), wherein the indication of barometric pressure sensor functioning is carried out without the use of engine operation.

14 . The method of claim 13 , wherein the vacuum level reached during activating the onboard vacuum pump to draw the vacuum across the reference orifice is linearly correlated with barometric pressure;
wherein as barometric pressure increases, the vacuum level reached during activating the onboard vacuum pump increases; and wherein as barometric pressure decreases, the vacuum level reached during activating the onboard vacuum pump decreases.

15 . The method of claim 13 , further comprising:
responsive to an indication that the one or more vehicle barometric pressure sensor(s) are functioning as desired; adjusting vehicle operating parameters based on barometric pressure indicated from the one or more vehicle barometric pressure sensor(s) during vehicle operation.

16 . The method of claim 15 , further comprising:
responsive to an indication that the one or more vehicle barometric pressure sensor(s) are not functioning as desired; adjusting the vehicle operating parameters based on the barometric pressure determined as the function of the vacuum level reached during activating the onboard vacuum pump.

17 . The method of claim 16 , wherein the adjusting vehicle operating parameters includes one of at least:
adjusting an open-loop throttle position of a throttle coupled to an air intake manifold of an engine of the vehicle, adjusting timing of spark provided to one or more cylinders of the engine, and adjusting one or more threshold(s) for an evaporative emissions test diagnostic procedure; where the evaporative emissions test diagnostic procedure includes evacuating a fuel system and/or an evaporative emissions control system of the vehicle, and monitoring a pressure bleed-up subsequent to sealing the fuel system and/or evaporative emissions control system.

18 . A system for a plug-in hybrid-electric vehicle, comprising:
an electric motor configured to drive vehicle wheels a fuel system including a fuel tank that supplies fuel to a vehicle engine; an evaporative emissions control system, selectively coupled to the fuel tank via a fuel tank isolation valve, and including a fuel vapor storage canister; an evaporative level check module (ELCM) positioned in a conduit between the fuel vapor storage canister and atmosphere, where the ELCM includes an electrically driven pump, a changeover valve operable between an first and a second position, and a reference orifice; an intake manifold of the vehicle engine; a barometric pressure sensor positioned in the intake manifold of the vehicle engine; and a controller storing instructions in non-transitory memory, that when executed, cause the controller to: while the engine is off; indicate barometric pressure via the barometric pressure sensor positioned in the intake manifold o

Assignees

• Ford Global Tech Llc

Inventors

• Dudar Aed M

Classifications

• F02M25/0854

  Details of the absorption canister · CPC title

• F02M35/1038

  for temperature or pressure · CPC title

• F02M35/104

  Intake manifolds · CPC title

• B60C23/00

  Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements · CPC title

• F02M25/0836 Primary

  Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold · CPC title