Crankcase integrity breach detection

Patent metadata

Field	Value
Publication number	US-9260990-B2
Application number	US-201213619941-A
Country	US
Kind code	B2
Filing date	Sep 14, 2012
Priority date	Sep 14, 2012
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

Methods and systems are provided for using a crankcase vent tube pressure or flow sensor for diagnosing a location and nature of crankcase system integrity breach. The same sensor can also be used for diagnosing air filter plugging and PCV valve degradation. Use of an existing sensor to diagnose multiple engine components provides cost reduction and sensor compaction benefits.

First claim

The invention claimed is:

1. A method for an engine, comprising:
measuring pressure in a crankcase vent tube with a pressure sensor arranged therein; and
with a controller, determining whether an intake air filter is degraded based on the measured crankcase vent tube pressure and setting a diagnostic code if the intake air filter is degraded.

2. The method of claim 1 , wherein determining whether the intake air filter is degraded includes determining whether the intake air filter is clogged based on the measured crankcase vent tube pressure.

3. The method of claim 2 , further comprising determining, with the controller, a change in the measured crankcase vent tube pressure during conditions when manifold air flow is higher than a threshold flow, wherein the determination of whether the intake air filter is clogged is further based on the change.

4. The method of claim 3 , further comprising, with the controller,
determining whether manifold air flow is higher than a threshold flow;
determining a deviation of the measured crankcase vent tube pressure from a reference pressure with the controller, and
determining a degree of air filter plugging based on the deviation of the measured crankcase vent tube pressure from the reference pressure during conditions when manifold air flow is higher than the threshold flow.

5. The method of claim 4 , wherein the reference pressure is an offset between an inferred barometric pressure and a pressure measured by the pressure sensor in the crankcase vent tube during conditions when manifold air flow is lower than the threshold flow.

6. The method of claim 2 , wherein the pressure sensor in the crankcase vent tube is a first pressure sensor, and wherein the determination of whether the intake air filter is degraded is further based on measurements of a second pressure sensor coupled downstream of the intake air filter and upstream of a compressor.

7. The method of claim 6 , wherein the determination of whether the intake air filter is degraded is further based on a difference between a first output of the first pressure sensor and a second output of the second pressure sensor during conditions when manifold air flow is higher than a threshold flow.

8. The method of claim 7 , further comprising determining that the air filter is clogged when a difference between the first output and the second output is greater than a threshold.

9. A method for an engine, comprising:
measuring pressure in a crankcase vent tube with a pressure sensor coupled therein;
estimating barometric pressure; and
with a controller, determining whether an intake air filter is plugged based on a difference between the measured crankcase vent tube pressure and the estimated barometric pressure during conditions when manifold airflow is higher than a threshold, and if so, setting a diagnostic code to indicate that the intake air filter is plugged.

10. The method of claim 9 , wherein the pressure sensor coupled in the crankcase vent tube is a first pressure sensor, and wherein barometric pressure is estimated by a second pressure sensor coupled downstream of the intake air filter and upstream of a compressor.

11. The method of claim 10 , wherein the determination of whether the intake air filter is plugged includes,
learning an offset between outputs of the first pressure sensor and the second pressure sensor during conditions when manifold airflow is lower than the threshold;
adjusting an output of the first pressure sensor based on the learned offset during conditions when manifold airflow is higher than the threshold; and
determining that the intake air filter is plugged if the adjusted output of the first pressure sensor deviates from the barometric pressure estimate by more than a threshold amount.

12. The method of claim 11 , further comprising:
determining a degree of air filter plugging based on deviation of the adjusted output of the first pressure sensor from the barometric pressure estimate, the degree of air filter plugging increasing as the deviation increases.

13. The method of claim 12 , further comprising setting a diagnostic code with the controller which indicates the degree of air filter plugging.

14. The method of claim 13 , further comprising limiting an engine speed responsive to the determination of the degree of air filter plugging.

15. The method of claim 10 , wherein the first pressure sensor is an absolute pressure sensor or a gauge pressure sensor.

16. An engine system, comprising:
an engine including an intake passage and a crankcase;
an air filter coupled in the intake passage upstream of a compressor;
a crankcase vent tube mechanically connected to the intake passage downstream of the air filter, the crankcase vent tube also mechanically connected to the crankcase via an oil separator, the crankcase vent tube located external to the engine;
a sensor coupled in the crankcase vent tube for estimating a vent tube air flow and/or pressure; and
a control system with computer readable non-transitory instructions stored in memory, including,
instructions stored in the memory for: during engine cranking, while manifold air flow is lower than a threshold:
learning an offset of the crankcase vent tube sensor based at least on a barometric pressure estimate; and

instructions stored in the memory for: during engine running, while manifold air flow is higher than the threshold:
correcting an output of the crankcase vent tube sensor based on the learned offset; and
setting a diagnostic code that indicates filter plugging based on a deviation of estimated crankcase vent tube pressure from the barometric pressure estimate.

17. The system of claim 16 , wherein the control system includes further non-transitory instructions stored in the memory for,
indicating a degree of filter plugging based on a degree of deviation of the estimated crankcase vent tube pressure from the barometric pressure estimate.

18. The system of claim 17 , wherein the crankcase vent tube sensor is an absolute pressure sensor and the barometric pressure estimate is estimated by a pressure sensor coupled in the intake passage upstream of the air filter.

19. The system of claim 17 , wherein the crankcase vent tube sensor is a gauge pressure sensor and the barometric pressure estimate is estimated by the gauge pressure sensor during engine cranking.

Assignees

• Rollinger John Eric
• Jentz Robert Roy
• Baltusis Paul Algis
• Ford Global Tech Llc

Inventors

• Rollinger John Eric
• Jentz Robert Roy
• Baltusis Paul Algis

Classifications

• F02M35/09

  Clogging indicators {; Diagnosis or testing of air cleaners (sensors therefore F02M35/10373)} · CPC title

• F02B77/08

  Safety, indicating, or supervising devices (thermal insulation F02B77/11; monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00) · CPC title

• F01M2013/0083

  Crankcase pressure · CPC title

• F02B29/0406

  Layout of the intake air cooling or coolant circuit · CPC title

• F02B37/00

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