Crankcase integrity breach detection

Patent metadata

Field	Value
Publication number	US-9664079-B2
Application number	US-201514838076-A
Country	US
Kind code	B2
Filing date	Aug 27, 2015
Priority date	Oct 3, 2014
Publication date	May 30, 2017
Grant date	May 30, 2017

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. Integrated CVT pressure readings are used to diagnose disconnection of the CVT on the air intake side and distinguish from disconnection on the crankcase side. Use of integrated pressure readings allows for a more reliable and quicker diagnosis even at lower engine airflows.

First claim

The invention claimed is:

1. A method for an engine, comprising:
indicating crankcase ventilation system breach based on an integrated value of actual crankcase vent tube pressure over a duration of transient engine airflow relative to an integrated value of expected crankcase vent tube pressure over the duration.

2. The method of claim 1 , wherein the indicating includes indicating crankcase ventilation system breach due to disconnection of a crankcase vent tube on an air intake side.

3. The method of claim 2 , wherein the indicating is based on a ratio of the integrated value of actual crankcase vent tube pressure over the duration of steady-state engine airflow relative to the integrated value of expected crankcase vent tube pressure, the crankcase ventilation system breach on the air intake side indicated in response to the ratio being lower than a threshold.

4. The method of claim 3 , further comprising, in response to the indicating, adjusting an engine actuator to limit engine power.

5. The method of claim 2 , wherein the duration of transient engine airflow includes a duration of transient engine airflow being higher than a threshold flow.

6. The method of claim 5 , wherein the duration is based on the integrated value of expected crankcase vent tube pressure.

7. The method of claim 6 , wherein the duration being based on the integrated value of expected crankcase vent tube pressure includes:
collecting actual vent tube pressure readings until the integrated value of expected crankcase vent tube pressure exceeds a threshold, and then discontinuing collecting actual vent tube pressure reading.

8. The method of claim 7 , further comprising,
comparing a first slope of each collected actual crankcase vent tube pressure reading to a second slope of a corresponding expected crankcase vent tube pressure reading; and
in response to a direction of the first slope of a given collected actual crankcase vent tube pressure reading not matching a direction of the second slope, rejecting the given collected actual crankcase vent tube pressure reading and not including the rejected reading in the integrated value of the actual crankcase vent tube pressure.

9. The method of claim 8 , further comprising,
estimating the transient engine airflow while collecting each actual crankcase vent tube pressure reading; and
in response to the estimated transient engine airflow being lower than the threshold flow when collecting a given actual crankcase vent tube pressure reading, rejecting the given collected actual crankcase vent tube pressure reading and not including the rejected reading in the integrated value of the actual crankcase vent tube pressure.

10. The method of claim 1 , wherein the actual vent tube pressure is estimated by one of a pressure sensor, a flow sensor, and a venturi coupled in the crankcase vent tube, and wherein the expected vent tube pressure is estimated by an engine controller based on engine airflow.

11. A method for an engine, comprising:
over a duration of transient engine airflow,

collecting a plurality of actual crankcase vent tube pressure readings while estimating corresponding expected crankcase vent tube pressure readings; and
after the duration,
integrating each of the collected plurality of actual crankcase vent tube pressure readings and the estimated corresponding expected crankcase vent tube pressure readings; and
indicating disconnection of a crankcase vent tube based on a ratio of a first integrated value of the actual pressure readings relative to a second integrated value of the estimated pressure readings being lower than a threshold.

12. The method of claim 11 , wherein the duration corresponds to a duration when the second integrated reaches a threshold value.

13. The method of claim 12 , further comprising,
rejecting one or more of the collected plurality of actual crankcase vent tube pressure readings in response to transient engine airflow being lower than a threshold airflow during the collecting or a slope of a collected actual crankcase vent tube pressure reading not matching a slope of a corresponding estimated crankcase vent tube pressure reading.

14. The method of claim 13 , wherein the rejecting includes excluding the rejected readings from the integrating.

15. The method of claim 14 , wherein the indicating includes setting a diagnostic code to indicate disconnection of the crankcase vent tube on a first side where the vent tube is coupled to an air intake passage of the engine.

16. The method of claim 15 , further comprising, in response to the indication, limiting engine boost.

17. A method for an engine, comprising:
indicating disconnection of a crankcase vent tube on a first side based on an integrated value of actual crankcase vent tube pressure readings collected over a first duration of transient engine airflow; and
indicating disconnection of the crankcase vent tube on a second, opposite side based on an integrated value of actual vent tube pressure readings collected over a second duration of engine cranking and run-up.

18. The method of claim 17 , wherein the first side is a side where the crankcase vent tube is coupled to an air intake passage, and wherein the second side is a side where the crankcase vent tube is coupled to a crankcase.

19. The method of claim 18 , wherein the integrated value of actual crankcase vent tube pressure readings collected over a first duration of steady-state engine airflow includes a first integrated change, the first integrated change including a first integrated rise in crankcase vent tube pressure, and wherein the integrated value of actual vent tube pressure readings collected over a second duration of engine cranking and run-up includes a second integrated change, the second integrated change including a transient dip.

20. The method of claim 17 , wherein the indicating disconnection on the first side is further based on an integrated value of expected crankcase vent tube pressure readings corresponding to the actual crankcase vent tube pressure reading collected over the first duration; and wherein the indicating disconnection on the second side is further based on an integrated value of expected crankcase vent tube pressure readings corresponding to the actual crankcase vent tube pressure reading collected over the second duration.

Assignees

• Ford Global Tech Llc

Inventors

• Jentz Robert Roy
• Rollinger John Eric
• Racelis Rommel
• Sweppy Michael Stephen

Classifications

• F01M13/00 Primary

  Crankcase ventilating or breathing · CPC title

• F02D41/22

  Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} · CPC title

• F01M13/021 Primary

  of negative pressure · CPC title

• F01M11/10 Primary

  Indicating devices; Other safety devices · CPC title

• F02M25/06

  adding lubricant vapours · CPC title