System and method for improving canister purging

Patent metadata

Field	Value
Publication number	US-9611816-B2
Application number	US-201514593985-A
Country	US
Kind code	B2
Filing date	Jan 9, 2015
Priority date	Jan 9, 2015
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

Systems and methods are provided for controlling a purging operation of a fuel vapor canister in a boosted engine. One method comprises purging stored fuel vapors from the fuel vapor canister to an inlet of the compressor via an ejector while bypassing a canister purge valve, the ejector being fluidically coupled to the fuel vapor canister by a distinct passage and motive flow through the ejector being regulated by a shut-off valve. The shut-off valve is temporarily closed in response to an operator tip-in event to discontinue the purging operation.

First claim

The invention claimed is:

1. A method for a boosted engine, comprising:
during boosted conditions,
flowing stored fuel vapors from a canister into an ejector, the flowing bypassing a canister purge valve and being regulated by a shut-off valve (SOV) positioned upstream of the ejector; and

responsive to an operator tip-in event,
closing the SOV; and
discontinuing the flowing of stored fuel vapors from the canister into the ejector.

2. The method of claim 1 , wherein during boosted conditions, stored fuel vapors flow from the canister to the ejector when the SOV is open and a motive flow exists through the ejector.

3. The method of claim 1 , further comprising, during non-boosted conditions, closing the SOV, opening the canister purge valve, and flowing stored fuel vapors from the canister via the canister purge valve into an engine intake, the flowing bypassing the ejector.

4. The method of claim 3 , wherein during non-boosted conditions stored fuel vapors flow from the canister via a valve and a sonic choke within the canister purge valve, the sonic choke positioned proximate to the valve in the canister purge valve.

5. The method of claim 3 , wherein the SOV is a continuously variable valve.

6. The method of claim 3 , wherein during boosted conditions the flowing of stored fuel vapors bypasses the canister purge valve when manifold pressure is higher than a pressure in the canister.

7. The method of claim 6 , further comprising, during boosted conditions, opening the canister purge valve and flowing additional stored fuel vapors via the canister purge valve when manifold pressure is lower than the pressure in the canister.

8. The method of claim 7 , wherein additional stored fuel vapors flow from the canister via the canister purge valve only when purging conditions are met.

9. The method of claim 8 , wherein the purging conditions include one or more of a hydrocarbon load of the canister being higher than a threshold load, a temperature of an emission device being higher than a threshold temperature, and an elapse of a threshold duration of vehicle and/or engine operation since a previous purging operation.

10. The method of claim 1 , further comprising not flowing stored fuel vapors via the canister purge valve responsive to the operator tip-in event.

11. A method for a boosted engine, comprising:
during boosted conditions,
closing a canister purge valve (CPV);
adjusting an opening of a shut-off valve (SOV) positioned upstream of an ejector in a compressor bypass passage; and
flowing fuel vapors from a canister only to the ejector, the flowing regulated by the SOV and bypassing the CPV; and

during non-boosted conditions,
closing the SOV;
opening the CPV; and
flowing fuel vapors from the canister only to the CPV, the flowing bypassing the ejector.

12. The method of claim 11 , wherein the CPV is opened based on one or more purging conditions being met, the purging conditions including one or more of a hydrocarbon load of the canister being higher than a threshold load, a temperature of an emission device being higher than a threshold temperature, and an elapse of a duration longer than a threshold duration subsequent to a previous purging operation.

13. The method of claim 11 , further comprising closing each of the SOV and the CPV in response to an operator pedal tip-in.

14. The method of claim 11 , further comprising closing each of the SOV and the CPV in response to an engine cold start.

15. A system for an engine, comprising:
an intake manifold;
an intake throttle;
a boost device including a compressor, the compressor positioned in an intake passage upstream of the intake throttle;
a canister purge valve comprising a solenoid valve and a sonic choke, the sonic choke coupled immediately downstream of the solenoid valve;
an inlet of the sonic choke fluidically coupled to an outlet of the solenoid valve;
an outlet of the sonic choke fluidically coupled to the intake manifold, the outlet of the sonic choke coupled to the intake manifold downstream of the intake throttle;
an ejector coupled in a compressor bypass passage, the compressor bypass passage including a shut-off valve;
a fuel vapor canister fluidically communicating with each of an inlet of the canister purge valve and a suction port of the ejector via distinct passages;
a motive inlet of the ejector coupled to the intake passage downstream of the compressor;
a motive outlet of the ejector coupled to the intake passage upstream of the compressor; and
a controller with instructions in non-transitory memory and executable by a processor for:
during boosted conditions,
adjusting a position of the shut-off valve (SOV) to generate vacuum at the ejector;
flowing stored fuel vapors from the fuel vapor canister into the suction port of the ejector, the flowing bypassing the canister purge valve; and
overriding the position of the SOV by temporarily closing the SOV during an operator tip-in event.

16. The system of claim 15 , wherein the controller includes further instructions for closing the solenoid valve in the canister purge valve during boosted conditions when a pressure in the intake manifold is higher than a pressure in the fuel vapor canister.

17. The system of claim 16 , wherein the controller includes further instructions for opening the solenoid valve in the canister purge valve during boosted conditions when the pressure in the intake manifold is lower than the pressure in the fuel vapor canister.

18. The system of claim 17 , wherein the controller includes further instructions for closing the solenoid valve in the canister purge valve responsive to the operator tip-in event.

19. The system of claim 18 , wherein the controller includes further instructions for, during non-boosted conditions, adjusting the SOV to a closed position and opening the solenoid valve in the canister purge valve to enable purging of stored fuel vapors from the fuel vapor canister via the solenoid valve and the sonic choke in the canister purge valve.

20. The system of claim 19 , wherein the controller includes further instructions for opening the SOV and closing the solenoid valve in the canister purge valve during an operator tip-out.

Assignees

• Ford Global Tech Llc

Inventors

• Pursifull Ross Dykstra
• Ulrey Joseph Norman

Classifications

• F02B37/162 Primary

  by bypassing, e.g. partially, intake air from pump inlet to pump outlet · CPC title

• F02D41/0007

  for control of turbo-charged or super-charged engines (control of the pumps per se F02B37/12) · CPC title

• F02D41/004

  Control of the valve or purge actuator, e.g. duty cycle, closed loop control of position · CPC title

• F02M35/10222

  Exhaust gas recirculation [EGR]; Positive crankcase ventilation [PCV]; Additional air admission, lubricant or fuel vapour admission · CPC title

• F02D41/26

  using computer, e.g. microprocessor · CPC title