Systems and methods for inferring barometric pressure

Patent metadata

Field	Value
Publication number	US-9890721-B2
Application number	US-201615211856-A
Country	US
Kind code	B2
Filing date	Jul 15, 2016
Priority date	Jul 15, 2016
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

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

The invention claimed is:

1. A system for a vehicle, comprising:
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 a 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 of the vehicle engine;
configure the changeover valve in the first position and activate the pump to draw a vacuum across the reference orifice;
indicate barometric pressure as a function of vacuum level reached during drawing the vacuum across the reference orifice; and
indicate the barometric pressure sensor is functioning as desired responsive to barometric pressure indicated as the function of vacuum level reached during drawing the vacuum across the reference orifice correlating with barometric pressure indicated via the barometric pressure sensor.

2. The system of claim 1 , further comprising:
one or more tire pressure monitoring sensor(s) coupled to one or more tires of wheels in the vehicle;
wherein the controller further stores instructions in non-transitory memory, that when executed, cause the controller to:
responsive to a lack of correlation between barometric pressure indicated as the function of vacuum level during drawing the vacuum across the reference orifice and barometric pressure indicated via the barometric pressure sensor;
monitor tire pressure via the one or more tire pressure monitoring sensor(s); and
indicate a change in barometric pressure during vehicle operating conditions responsive to a tire pressure change greater than a predetermined tire pressure change threshold.

3. The system of claim 2 , wherein the controller further stores instructions in non-transitory memory, that when executed, cause the controller to:
adjust vehicle operating parameters as a function of barometric pressure indicated via the barometric pressure sensor responsive to the indication that the barometric pressure sensor is functioning as desired;
adjust vehicle operating parameters as a function of barometric pressure indicated as the function of vacuum level reached during drawing the vacuum across the reference orifice responsive to lack of correlation between barometric pressure indicated via the barometric pressure sensor and barometric pressure indicated as the function of vacuum level reached during drawing vacuum across the reference orifice, and further responsive to tire pressure change less than the predetermined tire pressure change threshold; and
adjust vehicle operating parameters as a function of tire pressure responsive to the lack of correlation between barometric pressure indicated via the barometric pressure sensor and barometric pressure indicated as the function of vacuum level reached during drawing vacuum across the reference orifice, and further responsive to tire pressure change greater than the predetermined tire pressure change threshold;
wherein adjusting vehicle operating parameters includes one or more of adjusting open-loop throttle position, adjusting spark-timing, and adjusting one or more threshold(s) for evaporative emissions test diagnostic procedures.

4. A method comprising:
delivering fuel from a fuel system to an engine propelling a vehicle;
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.

5. The method of claim 4 , further comprising:
turning on the vacuum pump and drawing a vacuum across a reference orifice of fixed diameter.

6. The method of claim 5 , 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.

7. The method of claim 5 , 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.

8. The method of claim 4 , wherein efficiency of the vacuum pump decreases as barometric pressure decreases; and wherein
the efficiency of the vacuum pump increases as barometric pressure increases.

9. The method of claim 4 , 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.

10. The method of claim 9 , further comprising:
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.

11. The method of claim 9 , 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.

12. The method of claim 4 , 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.

13. The method of claim 4 , 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.

14. The method of claim 4 , wherein adjusting a vehicle operating parameter responsive to the estimate further comprises adjusting an evaporative emissions test diagnostic threshold.

15. The method of claim 4 , wherein the estimate of barometric pressure is determined without operation of the vehicle engine.

16. A method comprising:
indicating barometric pressure via one or more barometric pressure sensor(s) positioned in a 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 baromet

Assignees

• Ford Global Tech Llc

Inventors

• Dudar Aed M

Classifications

• F02M25/0854

  Details of the absorption canister · CPC title

• F02D41/0045 Primary

  Estimating, calculating or determining the purging rate, amount, flow or concentration · 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

• F02M35/1038

  for temperature or pressure · CPC title