Systems and methods for opportunistic vehicle evaporative emissions test diagnostic

• US 9,828,951 B2
• Filed: 04/06/2016
• Issued: 11/28/2017
• Est. Priority Date: 04/06/2016
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Dudar, Aed M.
• Primary Examiner(s): MOULIS, THOMAS N
• Application Number:
  US15/092,336
• Publication Number:
  US 20170292475A1
• Time in Patent Office: 601 Days
• Field of Search: 123516, 123518-520
• CPC Class Codes: F02D 2041/225 Leakage detection
• CPC Class Codes: F02D 2200/0404 Throttle position
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2200/50 said parameters being related to the vehicle or its components
• CPC Class Codes: F02D 2200/502 Neutral gear position
• CPC Class Codes: F02D 2200/701 Information about vehicle position, e.g. from navigation system or GPS signal
• CPC Class Codes: F02D 2200/703 Atmospheric pressure
• CPC Class Codes: F02D 41/0037 for diagnosing the engine diagnosis of purge control systems F02M25/0809
• CPC Class Codes: F02D 41/0225 in relation with the gear ratio or shift lever position
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02D 9/02 concerning induction conduits throttle valves, or arrangements thereof in conduits F02D9/08
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0854 Details of the absorption canister
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and systems are provided for opportunistically conducting an evaporative emissions test diagnostic procedure in order to indicate the presence or absence of undesired evaporative emissions in a vehicle evaporative emissions control system and fuel system. In one example, tire pressure and barometric pressure are monitored, and responsive to a tire pressure decrease in the absence of a barometric pressure increase, along with an indication that the vehicle transmission is in neutral and that the vehicle is not traveling downhill, the evaporative emissions system and fuel system may be sealed and the presence or absence of undesired evaporative emissions indicated based on a vacuum-build. In this way, an opportunistic evaporative emissions test may be conducted based on conditions favorable to conducting an emissions test procedure, and may thus increase test completion rates and reduce undesired evaporative emissions.

Claims

1. A method comprising:

responsive to an indication that a vehicle is in the process of a car wash event;

sealing a fuel system which supplies fuel to an engine propelling the vehicle and an evaporative emissions system coupled to the fuel system; and

conducting a diagnostic test for the presence of undesired evaporative emissions.

2. The method of claim 1, further comprising:

monitoring pressure in one or more tires of the vehicle; and

wherein

indicating that the vehicle is in the process of a car wash event includes indicating a tire pressure decrease greater than a predetermined threshold.

3. The method of claim 1, further comprising;

monitoring barometric pressure via a barometric pressure sensor positioned in an intake manifold of the engine; and

wherein

indicating that the vehicle is in the process of a car wash event includes an absence of change in barometric pressure.

4. The method of claim 3, further comprising:

controlling an intake air amount inducted into the engine intake manifold via a throttle; and

wherein

an absence of change in barometric pressure includes indicating that a throttle position is below a throttle position threshold.

5. The method of claim 1, further comprising:

monitoring vehicle pitch angle via one or more lateral sensors in the vehicle; and

wherein indicating that the vehicle is in the process of a car wash event includes indicating that the vehicle pitch angle is less than a threshold pitch angle.

6. The method of claim 1, wherein indicating that the vehicle is in the process of a car wash event includes indicating that a transmission of the vehicle is in a neutral gear state.

7. The method of claim 1, wherein the fuel system includes a fuel tank that supplies fuel to the engine, and the evaporative emissions system includes a fuel vapor canister configured to capture and store fuel vapors from the fuel tank;

and wherein

sealing the fuel system and evaporative emissions system comprises sealing the fuel system and evaporative emission system from atmosphere and from the engine; and

wherein

a fuel tank temperature decrease during the car wash event results in a vacuum build in the fuel system and evaporative emissions system.

8. The method of claim 7, wherein conducting the diagnostic test for the presence of undesired evaporative emissions includes indicating an absence of undesired evaporative emissions responsive to a vacuum build in the fuel system and evaporative emissions system greater than a predetermine vacuum threshold, or a rate of vacuum build greater than a predetermined threshold vacuum build rate.

9. The method of claim 1, wherein indicating that the vehicle is in the process of a car wash event further comprises:

indicating the car wash event based on one or more of a vehicle global positioning system (GPS) and onboard camera(s).

10. A system for a vehicle, comprising:

an engine;

a fuel tank, configured within a fuel system which supplies fuel to the engine;

a fuel vapor canister, configured within an evaporative emissions control system, fluidically coupled to an engine intake manifold via a canister purge valve, fluidically coupled to atmosphere via a canister vent valve; and

fluidically coupled to the fuel tank;

a barometric pressure sensor in the engine intake manifold;

one or more tire pressure sensors coupled to one or more tires of the vehicle;

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

monitor tire pressure in the one or more vehicle tires;

monitor barometric pressure via the barometric pressure sensor; and

responsive to an indication of a tire pressure decrease greater than a predetermined threshold and an absence of barometric pressure change;

in a first condition, seal the evaporative emissions system and fuel system from atmosphere and from the engine intake manifold by commanding closed the canister vent valve and canister purge valve without conducting an evaporative emissions test diagnostic on the fuel system and evaporative emissions system; and

in a second condition, seal the evaporative emissions system and fuel system from atmosphere and from the engine intake manifold by commanding closed the canister vent valve and canister purge valve and conduct an evaporative emissions test diagnostic on the fuel system and evaporative emissions system.

11. The system of claim 10, further comprising:

an intake throttle coupled to the engine intake manifold;

one or more lateral sensors; and

wherein

the controller further stores instructions in non-transitory memory, that when executed, cause the controller to;

control an intake air amount inducted into the engine intake manifold via the throttle;

monitor vehicle pitch angle via the one or more lateral sensors in the vehicle, wherein a vehicle pitch angle greater than a threshold pitch angle indicates the vehicle is traveling downhill; and

wherein the first condition includes a throttle position greater than a throttle position threshold, or the throttle position less than the throttle position threshold, the vehicle pitch angle less than the threshold pitch angle, and an indication that the vehicle is not in a neutral transmission gear state;

wherein the second condition includes the throttle position less than the throttle position threshold, the vehicle pitch angle less than the threshold pitch angle, and an indication that the vehicle is in a neutral transmission gear state; and

wherein

the throttle position greater than the throttle position threshold indicates accurate barometric pressure readings as monitored by the barometric pressure sensor.

12. The system of claim 11, wherein the controller further stores instructions in non-transitory memory, that when executed, cause the controller to:

responsive to an indication of tire pressure decrease greater than the predetermined threshold and a corresponding barometric pressure change;

adjust engine operating parameters based on barometric pressure change; and

responsive to an indication of tire pressure decrease greater than the predetermined threshold, the absence of barometric pressure change, the throttle position less than the throttle position threshold, and the vehicle pitch angle greater than the threshold pitch angle;

adjust engine operating parameters based on tire pressure change.

13. The system of claim 10, wherein the controller further stores instructions in non-transitory memory, that when executed, cause the controller to:

during the first condition, monitor tire pressure in the one or more vehicle tires; and

responsive to a tire pressure increase greater than a predetermined threshold;

unseal the evaporative emissions system and fuel system from atmosphere by commanding open the canister vent valve.

14. The system of claim 10, further comprising:

a fuel tank pressure transducer; and

wherein

the controller further stores instructions in non-transitory memory, that when executed, cause the controller to;

during the second condition, monitor pressure in the fuel system and evaporative emissions system; and

indicate an absence of undesired evaporative emissions responsive to vacuum in the fuel system and evaporative emissions system reaching a threshold vacuum, or responsive to a rate of vacuum build in the fuel system and evaporative emissions system greater than a predetermined threshold vacuum build rate.

15. The system of claim 14, wherein the controller further stores instructions in non-transitory memory, that when executed, cause the controller to:

adjust the threshold vacuum or threshold vacuum build rate based on one or more of ambient temperature, fuel tank fill level, fuel volatility, fuel temperature, or length and aggressiveness of a previous drive cycle.

16. The system of claim 11, further comprising:

an onboard global positioning system (GPS);

onboard cameras; and

wherein

the controller further stores instructions in non-transitory memory, that when executed, cause the controller to;

in the second condition, seal the evaporative emissions system and fuel system from atmosphere and from the engine intake manifold and conduct the evaporative emissions test diagnostic on the fuel system and evaporative emissions system responsive to an indication that the vehicle is in a car wash;

wherein indicating that the vehicle is in a car wash is based on GPS and/or the onboard cameras.

17. The system of claim 16, wherein the controller further stores instructions in non-transitory memory, that when executed, cause the controller to:

maintain sealed the evaporative emissions system and fuel system from atmosphere and from the engine intake manifold upon completion of the evaporative emissions test diagnostic until at least an indication of the vehicle transitioning from neutral to a forward gear state, an indication that the vehicle is no longer in the car wash based on GPS and/or the onboard cameras, or an indication that tire pressure has increased to a second threshold, the second threshold comprising a tire pressure indicating that the vehicle has exited the car wash and has begun driving.

18. A method for a vehicle comprising:

supplying fuel from a fuel tank to an engine which drives the vehicle;

storing fuel vapors from the fuel tank in an evaporative emissions system;

indicating conditions that the fuel tank is rapidly cooled by cold water striking the fuel tank; and

conducting an evaporative emissions test diagnostic procedure of the fuel tank and evaporative emission system responsive to the rapid cooling of the fuel tank.

19. The method of claim 18, further comprising:

monitoring pressure in one or more tires of the vehicle;

monitoring barometric pressure via a barometric pressure sensor positioned in an intake manifold of the engine;

monitoring vehicle pitch angle via one or more lateral sensors in the vehicle; and

wherein

indicating conditions that the fuel tank is rapidly cooled further comprises;

a tire pressure decrease greater than a predetermined threshold;

an absence of change in barometric pressure;

the vehicle pitch angle less than a threshold vehicle pitch angle; and

an indication that a transmission coupled to the engine is in a neutral gear state.

20. The method of claim 18, wherein cold water striking the fuel tank occurs during a car wash event;

wherein indicating the car wash event is further based on one or more of a vehicle global positioning system (GPS), and onboard camera(s); and

wherein

conducting the evaporative emissions test diagnostic procedure responsive to the rapid cooling of the fuel tank further comprises;

sealing the fuel system and the evaporative emissions system from atmosphere and from an intake manifold of the engine, wherein the evaporative emissions system includes a fuel vapor canister for capturing and storing fuel vapors; and

indicating an absence of undesired evaporative emissions from the fuel system and evaporative emissions system responsive to a vacuum build in the fuel system and evaporative emissions system reaching a predetermined threshold vacuum, or responsive to a rate of vacuum build greater than a predetermined threshold vacuum build rate.