Secondary air injection diagnostic system using pressure feedback
First Claim
1. A method for diagnosing system failures in a secondary air injection system that includes a pump that provides air to an exhaust system via a conduit and a valve that controls the flow of air through the conduit, comprising:
- measuring pressure in said conduit;
calculating a pump pressure component based on a barometric pressure and a valve pressure component based on a mass air flow (MAF) into an engine to provide a system pressure in said conduit during first, second and third operational phases of said secondary air injection system; and
comparing said measured pressure to said system pressure to identify system failures of said secondary air injection system.
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Accused Products
Abstract
A diagnostic system according to the present invention diagnoses system failure of a secondary air injection system. The secondary air injection system includes a pump that provides air to an exhaust system via a conduit and a valve that controls the flow of air through the conduit. A pressure sensor measures pressure in the conduit. A controller predicts pressure in the conduit during first, second and third operational phases of the secondary air injection system. The controller compares the measured pressure to the predicted pressure to evaluate operation of the secondary air injection system. During the first phase, the secondary air injection system is used to reduce vehicle emissions. During the second phase, the valve is shut while the pump is on. During the third phase, the pump is turned off while the valve is closed.
36 Citations
26 Claims
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1. A method for diagnosing system failures in a secondary air injection system that includes a pump that provides air to an exhaust system via a conduit and a valve that controls the flow of air through the conduit, comprising:
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measuring pressure in said conduit; calculating a pump pressure component based on a barometric pressure and a valve pressure component based on a mass air flow (MAF) into an engine to provide a system pressure in said conduit during first, second and third operational phases of said secondary air injection system; and comparing said measured pressure to said system pressure to identify system failures of said secondary air injection system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A diagnostic system for a secondary air injection system that includes a pump that provides air to an exhaust system via a conduit and a valve that controls the flow of air through the conduit, comprising:
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a pressure sensor for measuring pressure in said conduit; and a controller that calculates a pump pressure component based on a barometric pressure and a valve pressure component based on a mass air flow (MAF) into an engine to provide a system pressure during first, second and third operational phases of said secondary air injection system and that compares said measured pressure to said system pressure to identify system failures of said secondary air injection system. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification