Variable Valve Actuation Systems

Srivastava, Dhananjay Kumar; Das, Abhimanyu; Singh, Nitish Kumar

doi:10.1007/978-981-10-7575-9_4

Cited by 6 publications

(2 citation statements)

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“…[2][3][4][5] The variable valve events in the SI engine have the potential to reduce pumping loss at part-loads. [5][6][7][8] Among various valve timing strategies, the valve overlap can be achieved by varying the intake valve opening (IVO) and exhaust valve closing (EVC) timings. Chang et al 9 conducted the experiments on a multi-cylinder gasoline direct injection SI engine with variable intake and exhaust valve timings to extend the dilution limit using internal and external exhaust gas recirculation (EGR).…”

Section: Introductionmentioning

confidence: 99%

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Effect of internal exhaust gas recirculation on performance, combustion, and emissions in a PFI camless engine

Tripathy

Srivastava

2022

Env Prog and Sustain Energy

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The internal exhaust gas recirculation (EGR) into the intake manifold has a significant impact on fuel economy and emissions in the spark ignition (SI) engine. In this study, an in-house developed novel electro-pneumatic variable valve actuation (VVA) system was integrated on a PFI conventional engine and modified into PFI camless engine to vary the valve events independently. The potential of the developed VVA system in achieving the internal EGR by varying the intake valve opening (IVO) timings was widely investigated. The IVO timing was varied from 30 CA (crank angle) bITDC (before intake top dead center) to 40 CA aITDC (after intake top dead center). The spark timing was varied from 10 to 30 CA bCTDC (before compression top dead center). A 41% pumping mean effective pressure reduction was achieved with varying the IVO from 40 to À30 CA aITDC. It is due to the internal exhaust gas recirculation into the intake manifold that reduces the differential pressure between the manifold and combustion chamber. The entrapment of exhaust gas in the intake manifold dilutes the fresh charge, which deteriorates the combustion.However, advancing the spark timing from 10 to 30 CA bCTDC at IVO À30 CA aITDC, an 18% gas excahnge efficiency improvement was obtained. The fresh charge dilution forms an inhomogeneous mixture inside the cylinder that results in lower NO x emission. It is concluded that the developed VVA system has the potential to improve part loads efficiency by utilizing the internal EGR in a PFI camless engine.

show abstract

Section: Introductionmentioning

confidence: 99%

“…The variable valve events in the SI engine have the potential to reduce pumping loss at part‐loads 5–8 . Among various valve timing strategies, the valve overlap can be achieved by varying the intake valve opening (IVO) and exhaust valve closing (EVC) timings.…”

Section: Introductionmentioning

confidence: 99%