Method for increasing vacuum production for a vehicle

Patent metadata

Field	Value
Publication number	US-10677196-B2
Application number	US-201414269954-A
Country	US
Kind code	B2
Filing date	May 5, 2014
Priority date	May 5, 2014
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

Methods and systems for providing vacuum to a vehicle are described. In one example, a method adjusts an engine air-fuel ratio in response to provide additional vacuum to the vehicle.

First claim

The invention claimed is:

1. A method for operating an engine, comprising:
operating the engine at idle speed with a homogeneous air-fuel mixture;
generating a vacuum request while operating the engine at the idle speed; and
richening the homogeneous air-fuel mixture and reducing an engine air flow amount to maintain the engine at idle speed in response to the vacuum request.

2. The method of claim 1 , where the homogeneous air-fuel mixture is a stoichiometric air-fuel ratio when a vacuum request is not present, where the vacuum request is based on a sensed vacuum level of a vacuum reservoir external to the engine and an engine air intake, where the vacuum reservoir is in pneumatic communication with a brake booster, and where the richening of the homogeneous air-fuel mixture is performed when engine load is less than a threshold engine load.

3. The method of claim 1 , where richening the homogeneous air-fuel mixture includes richening the homogeneous air-fuel mixture to at least 0.8 lambda, and further comprising advancing intake valve closing in response to engine torque less than a threshold and a vacuum request generated above an altitude greater than a threshold altitude, then advancing spark timing in response to intake manifold vacuum less than a threshold vacuum, then richening an air-fuel ratio of the engine in response to intake manifold vacuum being less than the threshold vacuum.

4. The method of claim 3 , where richening the homogeneous air-fuel mixture is not performed when ambient barometric pressure is greater than a threshold pressure and where richening the homogeneous air-fuel mixture is performed when ambient barometric pressure is not greater than the threshold pressure.

5. The method of claim 1 , where richening the homogeneous air-fuel mixture is not performed when the engine is operated at an altitude less than a threshold altitude and where richening the homogeneous air-fuel mixture is performed when the engine is operated at an altitude greater than the threshold altitude.

6. The method of claim 1 , further comprising drawing air from a vacuum reservoir into the engine while the engine is operating with the richened homogeneous air-fuel mixture and biasing an engine air-fuel ratio lean in response to altitude greater than a threshold, vacuum reservoir vacuum less than a first threshold, engine intake manifold vacuum less than a second threshold, engine torque less than a threshold, and engine intake manifold vacuum not within a threshold of the second threshold.

7. The method of claim 1 , further comprising supplying the richened homogeneous air-fuel mixture to the engine in response to the vacuum request when the engine is not operating at idle speed and supplying a stoichiometric homogeneous air-fuel mixture to the engine in absence of the vacuum request.

8. A method for operating an engine, comprising:
generating a first vacuum request;
advancing cam driven intake valve closing timing, advancing spark timing, and richening an air-fuel mixture supplied to the engine in response to the first vacuum request;
generating a second vacuum request; and
richening the air-fuel mixture supplied to the engine, not advancing cam driven intake valve closing timing, and not advancing spark timing in response to the second vacuum request.

9. The method of claim 8 , where richening the air-fuel mixture includes richening the air-fuel mixture to a richer air-fuel ratio than 0.8 lambda, and further comprising:
biasing an engine air-fuel ratio lean in response to altitude greater than a threshold, vacuum reservoir vacuum less than a first threshold, engine intake manifold vacuum less than a second threshold, engine torque less than a threshold, and engine intake manifold vacuum not within a threshold of the second threshold.

10. The method of claim 8 , where the cam driven intake valve closing timing is advanced before advancing spark timing, where the first vacuum request and the second vacuum request are based on a vacuum level of a vacuum reservoir external to the engine, and where the vacuum reservoir is in pneumatic communication with a brake booster.

11. The method of claim 8 , where spark timing is advanced before richening the air-fuel mixture, where the richening of the air-fuel mixture, not advancing cam driven intake valve closing timing, and not advancing spark timing is performed when engine load is less than a threshold engine load, and where the threshold engine load is an engine idle load.

12. The method of claim 8 , where the first vacuum request occurs when an engine intake manifold vacuum is not less than a first threshold vacuum, and where the second vacuum request occurs when the engine intake manifold vacuum is within a second threshold vacuum level of the first threshold vacuum, and further comprising:
biasing a catalyst lean when engine intake manifold vacuum is not within the second threshold vacuum level of the first threshold vacuum.

13. The method of claim 8 , further comprising biasing the air-fuel mixture supplied to the engine lean in response to engine torque being greater than a threshold torque.

14. The method of claim 8 , further comprising not richening the air-fuel mixture supplied to the engine in response to ambient barometric pressure being greater than a threshold.

15. A system for operating an engine, comprising:
the engine;
a vacuum reservoir external to the engine and including a vacuum sensor; and
a controller including executable instructions stored in a non-transitory medium to operate the engine while a vacuum level of the vacuum reservoir is less than a threshold vacuum level with a rich air-fuel mixture supplied to the engine in response to the vacuum level of the vacuum reservoir being less than the threshold vacuum level.

16. The system of claim 15 , further comprising:
an intake valve adjustment device coupled to the engine, additional instructions for advancing intake valve timing of a cam driven intake valve via the intake valve adjustment device in response to the vacuum level of the vacuum reservoir being less than the threshold vacuum level; and
additional instructions to richen the air-fuel mixture in response to the vacuum level of the vacuum reservoir when engine load is less than a threshold engine load, where the threshold engine load is an engine idle load.

17. The system of claim 15 , further comprising:
an alternator coupled to the engine; and
additional instructions for reducing a load of the alternator applied to the engine in response to the vacuum level of the vacuum reservoir being less than the threshold vacuum level, and additional instructions to advance intake valve closing in response to engine torque less than a threshold and a vacuum request generated above an altitude greater than a threshold altitude, then advancing spark timing in response to intake manifold vacuum less than a threshold vacuum, then richening an air-fuel ratio of the engine in response to intake manifold vacuum being less than the threshold vacuum.

18. The system of claim 15 , further comprising additional instructions for supplying a lean air-fuel ratio to the engine in response to a torque level of the engine being greater than a threshold while the vacuum level of the vacuum reservoir is less than the threshold vacuum level.

19. The system of claim 15 , further comprising additional instructions for supplying a lean air-fuel ratio to the engine in response to an intake manifold vacuum being within a desired vacuum level of a threshold vacuum and a brake booster, the bra

Assignees

• Ford Global Tech Llc

Inventors

• Pursifull Ross Dykstra
• Cunningham Ralph Wayne

Classifications

• F02D2250/41

  Control to generate negative pressure in the intake manifold, e.g. for fuel vapor purging or brake booster · CPC title

• Y02T10/18

  Cross-Sectional Technologies · mapped topic

• F02M3/005 Primary

  Idling fuel enrichment with motor driven instead of driving; Switching the fuel supply from the main to idling jet system · CPC title

• F02D2200/703

  Atmospheric pressure · CPC title

• F02D2009/024

  Increasing intake vacuum · CPC title