Crankcase integrity breach detection

• US 9,382,823 B2
• Filed: 06/19/2015
• Issued: 07/05/2016
• Est. Priority Date: 09/14/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Rollinger, John Eric, Jentz, Robert Roy, Pursifull, Ross Dykstra
• Primary Examiner(s): Vo, Hieu T
• Application Number:
  US14/745,084
• Publication Number:
  US 20150285111A1
• Time in Patent Office: 382 Days
• US Class Current: 1/1
• CPC Class Codes: F01M 1/18 Indicating or safety devices concerning lubricant level F01M11/06, F01M11/12
• CPC Class Codes: F01M 13/00 Crankcase ventilating or breathing
• CPC Class Codes: F01M 13/0011 Breather valves
• CPC Class Codes: F01M 13/04 having means for purifying air before leaving crankcase, e.g. removing oil
• CPC Class Codes: F01M 2013/0038 Layout of crankcase breathing systems
• CPC Class Codes: F01M 2013/0083 Crankcase pressure
• CPC Class Codes: F01M 2013/0088 Rotation speed
• CPC Class Codes: F01M 2013/0094 Engine load
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/062 for starting F02D41/061 takes precedence
• CPC Class Codes: F02D 41/22 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 Class Codes: F02M 11/10 Register carburettors with rotatable throttling valves
• CPC Class Codes: F02M 35/10157 Supercharged engines
• CPC Class Codes: F02M 35/10222 Exhaust gas recirculation [EGR]; Positive crankcase ventilation [PCV]; Additional air admission, lubricant or fuel vapour admission
• CPC Class Codes: F02N 11/10 Safety devices F02N11/08 takes precedence
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

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.

Claims

1. An engine crankcase ventilation system, comprising:

an engine including an intake passage and a crankcase;

a starter motor;

a crankcase vent tube mechanically connected to the intake passage upstream of a compressor, the tube also mechanically connected to the crankcase via an oil separator, the vent tube located external to the engine;

a sensor coupled in the crankcase vent tube for estimating a vent tube pressure; and

a control system with computer readable instructions for,

during an engine start,

cranking the engine with the starter motor, and indicating crankcase ventilation system degradation based on each of a transient dip in the vent tube pressure being lower than a threshold amplitude during engine cranking when manifold airflow is below a threshold and a change in vent tube vacuum being lower than a change in manifold airflow during engine running when manifold air flow is above the threshold, wherein the engine is cranked by the starter motor at least before a first combustion event from rest.

2. The system of claim 1, wherein indicating crankcase ventilation system degradation includes setting a diagnostic code to indicate that the crankcase vent tube is disconnected from at least one of the intake passage and the crankcase.

3. The system of claim 2, wherein the sensor is one of a pressure sensor, a flow sensor, and a venturi, the system further comprising a barometric pressure sensor in the intake passage for estimating a barometric pressure, and wherein the vent tube pressure is estimated based on an output of the sensor in the crankcase vent tube, the output adjusted with an offset based on the estimated barometric pressure.

4. A method for an engine, comprising:

starting an engine from rest by cranking the engine with a starter motor;

indicating crankcase ventilation system degradation based on characteristics of a transient dip in crankcase vent tube pressure, during engine cranking; and

in response to the indication, limiting an engine load of the engine.

5. The method of claim 4, wherein based on characteristics of the transient dip includes based on an amplitude of the transient dip.

6. The method of claim 5, wherein the indicating includes indicating crankcase ventilation system degradation based on the amplitude of the transient dip being smaller than a threshold amount.

7. The method of claim 6, wherein the threshold amount is based on intake manifold vacuum during the engine cranking, the threshold amount increased as an expected flow through a PCV valve changes.

8. The method of claim 7, wherein during engine cranking includes before a first combustion event from rest.

9. The method of claim 8, wherein indicating crankcase ventilation system degradation includes indicating that a crankcase vent tube is disconnected.

10. The method of claim 9, wherein one end of the crankcase vent tube is mechanically coupled to an engine intake passage, upstream of a compressor, and another, opposite end of the crankcase vent tube is mechanically coupled to an engine crankcase via an oil separator.

11. The method of claim 6, wherein crankcase vent tube pressure for identifying the amplitude of the transient dip is estimated by a pressure sensor in a crankcase vent tube.

12. The method of claim 11, further comprising, after an engine speed reaches a threshold speed, indicating crankcase ventilation system degradation based on a change in crankcase vent tube pressure relative to a change in manifold airflow through the engine.

13. The method of claim 12, wherein the indicating includes indicating that the crankcase vent tube is disconnected based on a decrease in crankcase vent tube pressure not being proportional to an increase in manifold airflow over a duration while the engine speed is at or above the threshold speed.

14. The method of claim 4, wherein the indicating includes setting a diagnostic code.

15. A method for an engine, comprising:

starting an engine from rest by cranking the engine with a starter motor; and

indicating disconnection of a crankcase vent tube from an engine crankcase ventilation system based on a transient change in airflow through the crankcase vent tube during the engine cranking.

16. The method of claim 15, wherein the transient change in airflow is estimated by a flow sensor coupled in the crankcase vent tube.

17. The method of claim 16, wherein the flow sensor includes a venturi.

18. The method of claim 16, wherein the transient change in airflow is based on a transient dip in crankcase vent tube pressure estimated by a pressure sensor coupled in the crankcase vent tube.

19. The method of claim 18, wherein during engine cranking includes when manifold airflow is less than a threshold, the method further comprising, after the manifold airflow is at the threshold, indicating disconnection of the crankcase vent tube based on a rate of decrease in steady-state crankcase vent pressure relative to a rate of increase in steady-state manifold airflow while the engine is running above an idle speed.

20. The method of claim 19, wherein the indicating includes, indicating disconnection of the crankcase vent tube based on the rate of decrease in steady-state crankcase vent pressure not being proportional to the rate of increase in steady-state manifold airflow.