Air filter diagnostic
AssigneeGeneral Motors Corporation
InventorsJeffrey M. Polidan, Dennis P. Stenson, Jacqueline A. Jolliffe
Life of this patent
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Abstract
Significant restriction in an automotive internal combustion engine intake air filter is diagnosed over a wide range of engine operating conditions including low intake airflow rate conditions by qualifying transduced pressure drop across the air filter using airflow rate through the filter. A diagnostic count is maintained and updated in accord with detected significant restriction conditions. Adjustment values applied to the diagnostic count vary in accord with the degree of confidence associated with each detected significant restriction condition, such as indicated by varying engine intake airflow conditions.
Claims13
A method for diagnosing deterioration of an internal combustion engine intake air filter, the deterioration characterized by significant airflow restriction across the intake air filter, comprising the steps of:
- defining a minimum degree of airflow restriction across the intake air filter corresponding to a deteriorated intake air filter;
- generating a schedule of pressure drop values across a sample air filter having the established minimum degree of airflow restriction, as a function of airflow through the sample air filter;
- sensing pressure drop across the intake air filter;
- sensing airflow through the intake air filter;
- referencing the pressure drop value corresponding to the sensed airflow, from the schedule of pressure drop values;
- comparing the referenced pressure drop value to the sensed pressure drop;
- and
- diagnosing a deteriorated intake air filter when the sensed pressure drop exceeds the referenced pressure drop value.
An apparatus for diagnosing a deteriorated automotive internal combustion engine intake air filter, comprising:
- a memory device for storing a schedule of minimum pressure drop values across a deteriorated air filter as a function of corresponding airflow rate through the air filter, wherein the minimum pressure drop values of the schedule are substantially the minimum pressure drop across a deteriorated air filter through which engine intake air is passing at the corresponding airflow rate;
- a pressure sensor for sensing an intake air pressure drop across the air filter;
- an airflow sensor for sensing airflow rate through the air filter when the intake air pressure drop is sensed;
- referencing means for referencing a pressure drop value as a function of the sensed airflow rate;
- comparing means for comparing the sensed intake air pressure drop to the referenced pressure drop value;
- and
- determining means for determining that the air filter is deteriorated when the sensed intake air pressure drop exceeds the referenced pressure drop value.
A method for diagnosing a deterioration condition characterized by a significant increase in airflow restriction across an automotive air cleaner, comprising the steps of:
- storing a schedule of minimum pressure drop values across a deteriorated air cleaner as a function of airflow rate through the air cleaner, wherein the minimum pressure drop values of the schedule correspond to the minimum pressure drop across a deteriorated air cleaner through which engine intake air is passing at the corresponding airflow rate;
- repeating, while the engine is operating to draw intake air across the air cleaner, the steps of:
- sensing an air pressure drop across the air cleaner;
- sensing airflow rate through the air cleaner when the intake air pressure drop is sensed;
- referencing a minimum pressure drop value as a function of the sensed airflow rate, from the stored schedule;
- comparing the sensed air pressure drop to the referenced minimum pressure drop value;
- and
- diagnosing the deterioration condition when the sensed air pressure drop exceeds the referenced minimum pressure drop value.
Dependencies are inferred from the claim text.