Crankcase ventilation system diagnostic
First Claim
1. A method for diagnosing fault conditions in an internal combustion engine crankcase ventilation system, comprising the steps of:
- transducing crankcase pressure into a pressure signal;
repeatedly sampling the pressure signal over a test period;
storing a maximum sampled pressure;
storing a minimum sampled pressure;
comparing the maximum sampled pressure to a high pressure threshold following the test period;
diagnosing a fault condition when the maximum sampled pressure exceeds the high pressure threshold;
comparing the minimum sampled pressure to a low pressure threshold following the test period; and
diagnosing a second fault condition when the minimum sampled pressure is less than the low pressure threshold.
9 Assignments
0 Petitions
Accused Products
Abstract
A positive crankcase ventilation system diagnostic applied in an automotive internal combustion engine with a pressure sensor disposed in the system for continuous sensing of system pressure while the engine is running in a steady state operating condition, with minimum and maximum sensed pressure values stored during each of repeated test periods. Pressure values exceeding a predetermined normal range over at least one test period indicate a leak or restriction condition in the system. Small differences in pressure values over test periods indicate sensor or electrical fault conditions. Fault conditions are logged and are indicated if persistent.
73 Citations
10 Claims
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1. A method for diagnosing fault conditions in an internal combustion engine crankcase ventilation system, comprising the steps of:
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transducing crankcase pressure into a pressure signal; repeatedly sampling the pressure signal over a test period; storing a maximum sampled pressure; storing a minimum sampled pressure; comparing the maximum sampled pressure to a high pressure threshold following the test period; diagnosing a fault condition when the maximum sampled pressure exceeds the high pressure threshold; comparing the minimum sampled pressure to a low pressure threshold following the test period; and diagnosing a second fault condition when the minimum sampled pressure is less than the low pressure threshold. - View Dependent Claims (2, 3, 4, 5)
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6. In an automotive internal combustion engine crankcase ventilation system having an intake passage into the crankcase for providing fresh air thereto and a outlet passage from the crankcase to an engine intake manifold for drawing gasses out of the crankcase through a valve and recirculating the gasses into engine cylinders, an apparatus for diagnosing deterioration in the ventilation system, comprising:
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a pressure transducer positioned in the ventilation system to transduce the pressure thereof into a pressure signal; sampling circuitry for periodically sampling the pressure signal during a test period; a memory device for storing the sampled pressure signal having a maximum magnitude; a memory device for storing the sampled pressure signal having a minimum magnitude; a memory device for storing upper and lower threshold values; arithmetic logic circuitry for comparing the sampled pressure signal having the maximum magnitude to the upper threshold value and for comparing the sampled pressure signal having the minimum magnitude to the lower threshold value for diagnosing a fault condition; and an indicator for indicating a fault condition when the sampled pressure signal having the maximum magnitude exceeds the upper threshold value and when the sampled pressure signal having the minimum magnitude is less than the lower threshold value. - View Dependent Claims (7, 8, 9, 10)
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Specification