Crankcase integrity breach detection
First Claim
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1. A method for an engine having a PCV valve and a crankcase vent tube with an inlet coupled to an air intake upstream of a compressor and an outlet coupled to the crankcase, comprising:
- starting an engine from rest by cranking the engine with a starter motor;
differentiating via a controller between disconnection of the crankcase vent tube from degradation of the PCV valve based on characteristics of a transient dip in crankcase vent tube pressure, during engine cranking; and
in response to the differentiation, limiting an engine load of the engine via the controller.
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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.
36 Citations
20 Claims
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1. A method for an engine having a PCV valve and a crankcase vent tube with an inlet coupled to an air intake upstream of a compressor and an outlet coupled to the crankcase, comprising:
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starting an engine from rest by cranking the engine with a starter motor; differentiating via a controller between disconnection of the crankcase vent tube from degradation of the PCV valve based on characteristics of a transient dip in crankcase vent tube pressure, during engine cranking; and in response to the differentiation, limiting an engine load of the engine via the controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for an engine, comprising:
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starting an engine from rest by cranking the engine with a starter motor; decreasing opening of an electronically-controlled PCV valve coupled in a PCV line between a crankcase and an intake manifold at a location downstream of an intake throttle, wherein the opening of the PCV valve is commanded to a low flow position; 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, and indicating degradation of the PCV valve based on deviations of an estimated air flow profile of a crankcase vent tube from an expected air flow profile of the crankcase vent tube, the expected profile based on engine speed and manifold vacuum settings, including indicating that the PCV valve is stuck in a high flow position if the estimated profile is greater than the expected profile, and indicating that the PCV valve is stuck in the low flow position if the estimated profile is smaller than the expected profile. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification