Hydrocarbon retaining system and method
First Claim
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1. A method for an engine comprising:
- during warm-up, serially routing exhaust through two bricks arranged within a hydrocarbon trap to store exhaust hydrocarbons;
after warm-up, drawing air through a vent upstream of both bricks and purging the stored hydrocarbons in parallel, with the air, into a conduit coupled with the trap between the bricks;
after purging, and during select operating conditions when the engine continues to spin, again serially routing exhaust through the two bricks.
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Abstract
Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described.
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Citations
20 Claims
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1. A method for an engine comprising:
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during warm-up, serially routing exhaust through two bricks arranged within a hydrocarbon trap to store exhaust hydrocarbons; after warm-up, drawing air through a vent upstream of both bricks and purging the stored hydrocarbons in parallel, with the air, into a conduit coupled with the trap between the bricks; after purging, and during select operating conditions when the engine continues to spin, again serially routing exhaust through the two bricks. - 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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during warm-up, serially routing exhaust through two bricks arranged within a hydrocarbon trap to store exhaust hydrocarbons; after warm-up, drawing air through a vent upstream of both bricks and purging the stored hydrocarbons in parallel, with the air, to an engine intake via a conduit coupled with the trap between the bricks, while routing exhaust to bypass the hydrocarbon trap; after purging, and during select operating conditions when the engine continues to spin, again serially routing exhaust through the two bricks; and after again serially routing exhaust through the two bricks, again drawing air through the vent and purging the stored hydrocarbons in parallel, with the air, to the engine intake via the conduit while routing exhaust to bypass the hydrocarbon trap. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A method of operating an engine having a hydrocarbon-retaining system, comprising:
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during warm-up, serially routing exhaust through two bricks arranged within a hydrocarbon trap of the hydrocarbon-retaining system to store exhaust hydrocarbons; after warm-up, drawing air through a vent upstream of both bricks and purging the stored hydrocarbons, in parallel, with the air, to an engine intake via a conduit coupled with the trap between the bricks, while routing exhaust to bypass the hydrocarbon-retaining system; after purging, and during selected conditions when the engine continues to spin, again serially routing exhaust through the two bricks; after again serially routing exhaust through the two bricks, again drawing air through the vent and purging the stored hydrocarbons in parallel, with the air, to the engine intake via the conduit while routing exhaust to bypass the hydrocarbon-retaining system; and identifying degradation of the hydrocarbon-retaining system based on an exhaust air-fuel ratio during purging operation.
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Specification