#7101. Exhaust valve profile modulation for improved diesel engine curb idle aftertreatment thermal management

December 2026publication date
Proposal available till 10-05-2025
4 total number of authors per manuscript0 $

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Journal’s subject area:
Ocean Engineering;
Aerospace Engineering;
Mechanical Engineering;
Automotive Engineering;
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Abstract:
Rapid warm-up of a diesel engine aftertreatment system (ATS) is a challenge at low loads. Modulating exhaust manifold pressure (EMP) to increase engine pumping work, fuel consumption, and as a result, engine-outlet temperature, is a commonly used technique for ATS thermal management at low loads. This paper introduces exhaust valve profile modulation as a technique to increase engine-outlet temperature for ATS thermal management, without requiring modulation of exhaust manifold pressure. Experimental steady state results at 800 RPM/1.3 bar BMEP (curb idle) demonstrate that early exhaust valve opening with negative valve overlap (EEVO+NVO) can achieve engine-outlet temperature in excess of 255°C with 5.7% lower fuel consumption, 12% lower engine out NOx and 20% lower engine-out soot than the conventional thermal management strategy. Late exhaust valve opening with internal EGR via reinduction (LEVO+Reinduction) resulted in engine-outlet temperature in excess of 280°C, while meeting emission constraints at no fuel consumption penalty. This work also demonstrates that LEVO in conjunction with modulation of exhaust manifold pressure results in engine-outlet temperature in excess of 340°C while satisfying desired emission constraints. Aggressive use of LEVO can result in engine-outlet temperatures of 460°C, capable of active regeneration of DPF at curb idle, without the significant increase in engine-out soot emissions seen in previously studied strategies.
Keywords:
Aftertreatment thermal management; Certified Clean Idle; early exhaust valve opening; exhaust pressure modulation; HD-FTP; idle; internal EGR; late exhaust valve opening; maximally shut VGT; variable valve actuation

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