METHOD AND SYSTEM FOR FUEL VAPOR MANAGEMENT
First Claim
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1. A method for a boosted engine, comprising:
- during boosted conditions,generating a vacuum at a first ejector using compressor bypass air flow;
applying the vacuum to a crankcase to draw fuel vapors into the first ejector; and
during cruising conditions and while drawing the fuel vapors to the first ejector,flowing additional fuel vapors from the crankcase to an intake manifold via a crankcase ventilation valve.
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Abstract
Methods and systems are provided for ventilating a crankcase in an engine. In one example, when the engine is operating boosted under cruising conditions, fuel vapors from the crankcase may flow to each of a compressor inlet and an intake manifold of the engine. In this way, the crankcase may be effectively purged.
23 Citations
20 Claims
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1. A method for a boosted engine, comprising:
during boosted conditions, generating a vacuum at a first ejector using compressor bypass air flow; applying the vacuum to a crankcase to draw fuel vapors into the first ejector; and during cruising conditions and while drawing the fuel vapors to the first ejector, flowing additional fuel vapors from the crankcase to an intake manifold via a crankcase ventilation valve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for an engine that is boosted, comprising:
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when the engine is operating boosted, drawing a first portion of fuel vapors from a first port of a crankcase into a first aspirator coupled in a compressor bypass passage, the first portion of fuel vapors bypassing a crankcase ventilation (CV) valve; and when pressure in an intake manifold is lower than barometric pressure while the engine is boosted, using vacuum in the intake manifold to draw a second portion of fuel vapors from the first port of the crankcase directly into the intake manifold; and drawing a third portion of fuel vapors from the first port of the crankcase into a second aspirator coupled in a throttle bypass passage, the third portion of fuel vapors flowing through the second aspirator into the intake manifold. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A system, comprising:
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an engine including an intake manifold; a compressor positioned in an intake passage for providing a boosted aircharge; a compressor bypass passage coupled around the compressor, the compressor bypass passage including a compressor bypass valve; a first aspirator coupled to the compressor bypass passage; a throttle coupled in the intake passage; a throttle bypass passage coupled around the throttle, the throttle bypass passage including a throttle bypass valve; a second aspirator coupled to the throttle bypass passage; a crankcase; an outlet port of the crankcase coupled fluidically to each of the first aspirator, the second aspirator, and the intake manifold; a crankcase ventilation (CV) valve regulating flow between the outlet port of the crankcase and each of the second aspirator and the intake manifold, the CV valve not regulating flow of vapors between the outlet port of the crankcase and the first aspirator. - View Dependent Claims (19, 20)
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Specification