Systems and methods for indicating canister purge valve degradation

Patent metadata

Field	Value
Publication number	US-10167823-B2
Application number	US-201615202288-A
Country	US
Kind code	B2
Filing date	Jul 5, 2016
Priority date	Jul 5, 2016
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

Methods and systems are provided for indicating whether a canister purge valve in a vehicle evaporative emissions control system is degraded. In one example, an air intake system hydrocarbon (AIS HC) trap temperature may be monitored during a refueling event, and responsive to an indication that the AIS HC trap temperature change is greater than a predetermined threshold, it may be indicated that the canister purge valve is degraded. In this way, diagnosis of whether a vehicle canister purge valve is degraded may be indicated without the use of engine manifold vacuum, and may be advantageous for vehicles configured to operate for significant amounts of time without engine operation, or without intake manifold vacuum.

First claim

The invention claimed is:

1. A method comprising:
monitoring a fuel vapor loading state of an adsorbent material positioned in an engine air intake while fuel is being added to a fuel tank that supplies fuel to a vehicle engine; and
responsive to an indication that an increase in the fuel vapor loading state is greater than a first predetermined threshold but less than a second predetermined threshold:
indicating a canister purge valve configured to seal the fuel tank from an intake manifold is degraded, and not actively purging the adsorbent material; and
responsive to an indication that an increase in the fuel vapor loading state is greater than the first predetermined threshold and greater than the second predetermined threshold:
indicating the canister purge valve configured to seal the fuel tank from the intake manifold is degraded, and actively purging the adsorbent material.

2. The method of claim 1 , further comprising:
adsorbing fuel vapors from the fuel tank in an adsorbent material contained in a fuel vapor canister positioned in an evaporative emissions control system of a vehicle;
wherein fuel vapors from the fuel tank generated while adding fuel to the fuel tank are routed from the fuel tank to the fuel vapor canister and not to the adsorbent material positioned in the engine air intake responsive to the canister purge valve functioning as desired; and
wherein fuel vapors from the fuel tank generated while adding fuel to the fuel tank are routed from the fuel tank to the adsorbent material positioned in the engine air intake through the canister purge valve responsive to the canister purge valve being degraded.

3. The method of claim 2 , wherein the fuel vapor loading state of the adsorbent material positioned in the engine air intake and a fuel vapor loading state of the fuel vapor canister are indicated based on temperature changes of the adsorbent material positioned in the engine air intake and temperature changes of the adsorbent material contained in the fuel vapor canister;
wherein temperature changes of the adsorbent material positioned in the engine air intake are monitored by one or more temperature sensor(s) positioned in the adsorbent material positioned in the engine air intake; and
wherein temperature changes of the adsorbent material contained in the fuel vapor canister are monitored by the one or more temperature sensor(s) positioned in the adsorbent material contained in the fuel vapor canister.

4. The method of claim 3 , wherein actively purging the adsorbent material further comprises:
in a first condition, spinning the vehicle engine fueled in a forward direction and commanding open an air intake throttle that controls airflow to an intake manifold of the vehicle engine, where spinning the vehicle engine fueled in the forward direction creates vacuum in the intake manifold; and
in a second condition, spinning the vehicle engine unfueled in a reverse direction and commanding closed the air intake throttle, where spinning the vehicle engine unfueled in the reverse direction creates vacuum in an exhaust manifold of the engine.

5. The method of claim 4 , wherein the first condition further comprises:
commanding or maintaining closed the canister purge valve; and
wherein vacuum created in the intake manifold by spinning the vehicle engine fueled in the forward direction draws atmospheric air past the air intake throttle and across the adsorbent material positioned in the engine air intake, desorbing fuel vapors from the adsorbent material and routing the desorbed fuel vapors to the vehicle engine where the fuel vapors are combusted.

6. The method of claim 5 , wherein the first condition further comprises:
monitoring temperature change during the desorbing of fuel vapors from the adsorbent material positioned in the engine air intake via the one or more temperature sensor(s) positioned in the adsorbent material positioned in the engine air intake; and
indicating the adsorbent material positioned in the engine air intake is clean responsive to temperature change below a predetermined threshold.

7. The method of claim 6 , wherein responsive to an indication that the adsorbent material in the intake manifold is clean, resuming default driving conditions based on vehicle operator demand.

8. The method of claim 4 , wherein the second condition further comprises:
commanding open the canister purge valve; and
wherein vacuum created in the exhaust manifold by spinning the vehicle engine unfueled in reverse draws atmospheric air across the adsorbent material positioned in the engine air intake, desorbing fuel vapors from the adsorbent material and routing the desorbed fuel vapors to the fuel vapor canister positioned in the evaporative emissions control system where the fuel vapors are adsorbed.

9. The method of claim 8 , wherein the second condition further comprises:
monitoring temperature change of the adsorbent material positioned in the engine air intake during the desorption of fuel vapors, where temperature change below a threshold indicates fuel vapor load of the adsorbent material positioned in the engine air intake below a first threshold;
monitoring temperature change of the adsorbent material contained in the fuel vapor canister during the adsorption of fuel vapors, where temperature change above another threshold indicates fuel vapor load of the adsorbent material contained in the fuel vapor canister above a second threshold; and
stopping spinning the vehicle engine unfueled in reverse responsive to fuel vapor load of the adsorbent material positioned in the intake manifold below the first threshold, or responsive to fuel vapor load of the adsorbent material contained in the fuel vapor canister above the second threshold.

10. The method of claim 4 , wherein the first condition includes a vehicle-on condition within a predetermined time duration of an indication of completion of fuel being added to the fuel tank; and wherein the second condition includes the vehicle being maintained off for the predetermined time duration.

11. The method of claim 4 , further comprising:
selectively coupling the fuel tank to the adsorbent material contained in the fuel vapor canister positioned in the evaporative emissions control system via a fuel tank isolation valve positioned in a conduit between the fuel tank and the fuel vapor canister;
wherein the fuel tank isolation valve is commanded open prior to adding fuel to the fuel tank, and is maintained open during adding fuel to the fuel tank; and
wherein the second condition includes commanding closed the fuel tank isolation valve to seal the fuel tank from the engine air intake and from the fuel vapor canister.

12. A system for a hybrid vehicle, comprising:
an engine comprising one or more cylinders, each cylinder including an intake valve and an exhaust valve;
fuel injectors for each of the one or more cylinders;
a spark plug for each of the one or more cylinders;
an engine exhaust;
a fuel vapor canister selectively coupled to an engine intake manifold via a canister purge valve;
a fuel tank that supplies fuel to the engine, the fuel tank selectively coupled to the fuel vapor canister via a fuel tank isolation valve;
an air intake system hydrocarbon trap positioned in the engine intake manifold;
one or more temperature sensor(s) positioned in the fuel vapor canister;
one or more temperature sensor(s) positioned in the air intake system hydrocarbon trap; and
a controller configured with instructions stored in non-transitory memory, that when executed, cause the controller to:
responsive to a request for refueling of the fuel tank, command open the fuel tank isolation

Assignees

• Ford Global Tech Llc

Inventors

• Dudar Aed M

Classifications

• F02M35/0218 Primary

  acting by absorption or adsorption; trapping or removing vapours or liquids, e.g. originating from fuel · CPC title

• F02M25/0809

  Judging failure of purge control system · CPC title

• F02D2200/0802

  Temperature of the exhaust gas treatment apparatus · CPC title

• F02D41/042

  for stopping the engine · CPC title

• F02D41/0035

  to achieve a special effect, e.g. to warm up the catalyst · CPC title