Method and system for vacuum generation

Patent metadata

Field	Value
Publication number	US-9267464-B2
Application number	US-201414266411-A
Country	US
Kind code	B2
Filing date	Apr 30, 2014
Priority date	Apr 30, 2014
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

Various systems and methods are described for reducing motive flow rate through an aspirator. In one example, a method comprises flowing intake air, heated upon passage through an interstitial space of a double wall exhaust system, through an aspirator coupled to an engine vacuum consumption device to reduce motive mass flow rate at the aspirator as exhaust temperature increases. A position of an intake throttle may be adjusted based on the motive flow rate from the aspirator.

First claim

The invention claimed is:

1. A method for an engine, comprising:
flowing intake air, heated upon passage through an interstitial space of a double wall exhaust manifold, through an aspirator coupled to an engine vacuum consumption device to reduce motive mass flow rate at the aspirator as exhaust temperature increases;
comparing an actual temperature of an engine intake manifold aircharge to an expected temperature; and
indicating plugging of the interstitial space based on the comparison.

2. The method of claim 1 , wherein the aspirator is not coupled to an aspirator shut-off valve, and wherein the heated intake air flows through the aspirator en route from the interstitial space to an engine intake air, downstream of a throttle, without flowing through any other devices between the interstitial space and the engine intake.

3. The method of claim 1 , further comprising, drawing vacuum at a neck of the aspirator and applying the drawn vacuum to the vacuum consumption device.

4. The method of claim 3 , wherein the vacuum consumption device is a brake booster.

5. The method of claim 1 , wherein flowing the intake air further includes flowing from upstream of an intake throttle to an intake manifold, downstream of the intake throttle, via the aspirator.

6. The method of claim 5 , wherein flowing the intake air from upstream of the intake throttle further includes flowing from one of upstream of an intake compressor, when the engine is not boosted, and downstream of a charge air cooler, when the engine is boosted.

7. The method of claim 6 , further comprising, during engine idling, feed-forward adjusting the intake throttle based on an amount of aspirator mass flow rate, the aspirator mass flow rate based on a temperature of motive flow through the aspirator.

8. The method of claim 7 , wherein the temperature of motive flow through the aspirator is inferred based on exhaust temperature.

9. The method of claim 8 , wherein adjusting the intake throttle further includes, moving the intake throttle towards a more closed position as the temperature of the motive flow through the aspirator decreases, and moving the intake throttle towards a more open position as the temperature of the motive flow through the aspirator increases.

10. The method of claim 9 , further comprising, after the intake throttle reaches a fully closed position, retarding spark timing responsive to an amount of aspirator leakage flow while maintaining the intake throttle at the fully closed position.

11. The method of claim 9 , further comprising, feedback adjusting the intake throttle based on an expected intake airflow relative to an estimated intake airflow.

12. A method for an engine, comprising:
flowing intake air through an interstitial space of a double wall exhaust manifold, and then through an aspirator before delivering the intake air to an engine intake manifold; and
during a first idling condition, when exhaust temperature is higher, feed-forward adjusting an intake throttle to a more open position during the flowing; and
during a second idling condition, when the exhaust temperature is lower, feed-forward adjusting the intake throttle to a more closed position during the flowing;
comparing an actual temperature of an engine intake manifold aircharge to an expected temperature; and
indicating plugging of the interstitial space based on the comparison.

13. The method of claim 12 , wherein during the first idling condition, a temperature of motive flow through the aspirator is hotter, and wherein during the second idling condition, the temperature of motive flow through the aspirator is cooler.

14. The method of claim 13 , wherein during the first idling condition, an aspirator mass flow rate is lower and wherein during the second idling condition, the aspirator mass flow rate is higher.

15. The method of claim 12 , wherein the aspirator is not a valved aspirator, the method further comprising, during both first and second idling conditions, drawing vacuum at a neck of the aspirator and applying the drawn vacuum to a vacuum consumption device, wherein the vacuum consumption device is a brake booster, a fuel vapor canister, or a vacuum actuated valve.

16. A system for an engine, comprising:
an engine intake manifold;
an intake throttle;
a compressor;
an exhaust manifold having a double wall exterior defining an interstitial space;
a conduit coupling the interstitial space to the intake manifold downstream of the compressor and the intake throttle;
an un-valved aspirator positioned in the conduit, the aspirator coupled to a vacuum consumption device; and
a controller configured with computer readable instructions stored on non-transitory memory to:
during an engine cold-start,
draw intake air into the interstitial space from upstream of the intake throttle;
flow intake air heated upon passage through the interstitial space through the aspirator;
draw a vacuum at the aspirator; and adjust a position of the intake throttle based on an amount of airflow through the aspirator, the amount of airflow estimated based on exhaust temperature during the engine cold-start;
wherein the system further includes a temperature sensor coupled to the intake manifold, downstream of the intake throttle, and wherein the controller includes further instructions for:
comparing an actual temperature of an engine intake manifold aircharge to an expected temperature; and
indicating plugging of the interstitial space based on the comparison.

17. The system of claim 16 , wherein the controller includes further instructions for, moving the intake throttle towards a more open position as the amount of airflow through the aspirator decreases, wherein the amount of airflow through the aspirator decreases as the exhaust temperature increases.

18. The system of claim 16 , wherein the controller includes further instructions for, applying the vacuum drawn at the aspirator to the vacuum consumption device, wherein the vacuum consumption device is a brake booster.

19. The system of claim 16 , wherein the actual temperature is based on an output of the temperature sensor, wherein the expected temperature is based on an aspirator mass flow rate, and wherein the indicating of plugging of the interstitial space further includes indicating that the interstitial space is plugged in response to the actual temperature being lower than the expected temperature by more than a threshold amount.

Assignees

• Ford Global Tech Llc

Inventors

• Ulrey Joseph Norman
• Pursifull Ross Dykstra

Classifications

• F02B37/00

  Engines characterised by provision of pumps driven at least for part of the time by exhaust · CPC title

• F02D31/003

  for idle speed control · CPC title

• F02D41/0002

  Controlling intake air · CPC title

• F02P5/1508

  with particular means during idling · CPC title

• F02D2041/141

  using a feed-forward control element · CPC title