Positive crankcase ventilation system diagnostic
AssigneeGeneral Motors Corporation
InventorGregory Francis O'Daniel
Life of this patent
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Abstract
A diagnostic for diagnosing fault conditions including leak and restriction conditions in a positive crankcase ventilation (PCV) system of an internal combustion engine in which temperature of intake air passed to the PCV system and temperature of exhaust gas exhausted from the PCV system are monitored under test conditions and a temperature change across the PCV system generated therefrom for comparison to an expected temperature change reference as a function of current engine operating conditions. A significant persistent deviation of the temperature change away from the expected temperature change is indicated as a fault condition of the PCV system.
Claims13
A diagnostic method for an internal combustion engine positive crankcase ventilation system having an intake air passage for admitting intake air to an engine crankcase and having an outlet gas passage for returning exhaust gas from the engine crankcase to an engine inlet air path, comprising the steps of:
- sampling intake air temperature;
- sampling exhaust gas temperature;
- generating a temperature difference value as a function of a difference between the intake air temperature and the exhaust gas temperature;
- comparing the temperature difference value to a stored expected temperature difference;
- and
- diagnosing a positive crankcase ventilation system fault condition when the temperature difference value deviates significantly from the stored expected temperature difference.
A method for diagnosing fault conditions in an internal combustion engine crankcase ventilation system in which intake air is passed through an inlet passage to an engine crankcase and is exhausted from the crankcase through an outlet passage, comprising the steps of:
- sampling inlet air temperature in the inlet passage;
- sampling outlet air temperature in the outlet passage;
- determining a temperature change value indicating the change in temperature of air passing through the positive crankcase ventilation system as a function of the sampled inlet and outlet air temperature;
- comparing the temperature change value to an expected temperature change value;
- and
- indicating a fault condition when the air temperature change value is significantly different than the expected air temperature change value.
A diagnostic method for diagnosing fault conditions including leak and restriction conditions in a positive crankcase ventilation system including an inlet air passage for passing intake air from an engine intake air path to an engine crankcase and an outlet air passage for exhausting gases from the crankcase to an engine intake manifold, comprising the repeated steps of:
- sensing crankcase intake air temperature;
- sensing crankcase exhaust gas temperature;
- calculating a temperature difference value representing a difference between the sensed crankcase intake air temperature and the sensed crankcase exhaust gas temperature;
- comparing the temperature difference value to an expected temperature difference;
- incrementing a fault counter when the temperature difference value is substantially different than the expected temperature difference;
- comparing the fault counter to a count limit;
- and
- indicating a positive crankcase ventilation system fault condition when the fault counter exceeds the count limit.
Dependencies are inferred from the claim text.