Crankcase ventilation tube disconnect detection via humidity sensor

• US 9,303,592 B2
• Filed: 11/28/2012
• Issued: 04/05/2016
• Est. Priority Date: 11/28/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Pursifull, Ross Dykstra
• Primary Examiner(s): Vo, Hieu T
• Assistant Examiner(s): MANLEY, SHERMAN D
• Application Number:
  US13/687,923
• Publication Number:
  US 20140149015A1
• Time in Patent Office: 1,224 Days
• Field of Search: 123472-474
• US Class Current: 1/1
• CPC Class Codes: F02M 25/06 adding lubricant vapours
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Methods and systems are provided for detecting degradation of a crankcase ventilation tube. Humidity sensed from a humidity sensor in the crankcase ventilation tube may provide an indication of crankcase ventilation tube disconnection during different engine operating conditions. The humidity sensor may further provide diagnosis of humidity sensor function and engine degradation.

Claims

1. An engine method, comprising:

estimating ambient and crankcase ventilation tube humidity with a humidity sensor positioned in a crankcase ventilation tube;

measuring intake manifold pressure with a pressure sensor;

if the measured intake manifold pressure is less than barometric pressure, adjusting engine operation based on estimated ambient humidity; and

if the measured intake manifold pressure is greater than or equal to barometric pressure, indicating whether the crankcase ventilation tube is degraded based on the estimated ambient humidity.

2. The method of claim 1, further comprising indicating no degradation responsive to estimated humidity of the crankcase ventilation tube being greater than a threshold humidity while intake manifold pressure is greater than barometric pressure and indicating degradation of the crankcase ventilation tube if the humidity of the crankcase ventilation tube is less than the threshold humidity, the degradation including disconnection of the crankcase ventilation tube.

3. The method of claim 2, wherein the threshold humidity is estimated ambient humidity plus a threshold amount.

4. The method of claim 2, wherein when the intake manifold pressure is greater than the barometric pressure the engine is boosted.

5. The method of claim 2, wherein the humidity saturates at a relative humidity of substantially 100% after the intake manifold pressure is greater than barometric pressure for a duration.

6. The method of claim 5, wherein no degradation is indicated when the humidity is substantially 100%.

7. The method of claim 1, further comprising approximating a blowby rate based on a rate of humidity increase responsive to the intake manifold pressure increasing from below barometric pressure to above barometric pressure.

8. The method of claim 7, wherein engine degradation is indicated responsive to the blowby rate above a threshold rate.

9. The method of claim 1, further comprising diagnosing functionality of the humidity sensor.

10. An engine method, comprising:

adjusting engine operating parameters based on humidity, the humidity sensed in a crankcase ventilation tube; and

indicating degradation of the crankcase ventilation tube based on the sensed humidity and an engine boosting level, and alerting a vehicle operator of the degradation.

11. The method of claim 10, wherein the engine operating parameters include one or more of a grille shutter system, an electric fan, a variable volume charge air cooler, charge air cooler purging operations, a throttle opening to control air flow rate, spark timing, and downshifting operations.

12. The method of claim 10, wherein the indicating degradation includes indicating the crankcase ventilation tube is disconnected responsive to the engine being boosted and the sensed humidity being less than a threshold humidity.

13. The method of claim 10, wherein the indicating degradation includes indicating the crankcase ventilation tube is connected responsive to the engine being boosted and the sensed humidity being greater than a threshold humidity, the threshold humidity being a threshold amount above ambient humidity.

14. The method of claim 10, further comprising indicating ambient humidity based on the sensed humidity responsive to the engine not being boosted.

15. The method of claim 10, further comprising, during a transient condition, when the engine goes from being unboosted to boosted, approximating a blowby rate based on a rate of increase in humidity.

16. The method of claim 15, wherein a higher blowby rate indicates a larger amount of engine degradation.

17. A system for an engine comprising:

a positive crankcase ventilation system, the positive crankcase ventilation system including a crankcase ventilation tube, the crankcase ventilation tube connected at a first end to a fresh air intake and at a second end to a crankcase;

a humidity sensor, the humidity sensor located inside the crankcase ventilation tube;

a manifold absolute pressure sensor; and

a controller with computer readable instructions for adjusting engine operating parameters based on humidity sensed by the humidity sensor and indicating degradation of the crankcase ventilation tube based on humidity sensed by the humidity sensor and engine boosting.