Achievement of Medium Engine Speed and Load Premixed Diesel Combustion with Variable Valve Timing

Murata, Yutaka; Kusaka, Jin; Odaka, Matsuo; Daisho, Yasuhiro; Kawano, Daisuke; Suzuki, Hisakazu; Ishii, Hajime; Goto, Yuichi

doi:10.4271/2006-01-0203

Cited by 54 publications

(21 citation statements)

References 22 publications

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“…Recently reviewed by Musculus et al [1] and investigated for applications in both light-duty [2][3][4][5][6] and heavy-duty [7][8][9][10] engines, LTC uses a combination of greater dilution and premixing of reactant mixtures compared to conventional diesel combustion [11] to suppress formation of NO x and soot. One common method of dilution is exhaust gas recirculation (EGR), which introduces high-heat-capacity species such as CO 2 and H 2 O into the cylinder, reduces the flame temperature, * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine

O’Connor

Musculus

Pickett

2016

Combustion and Flame

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a b s t r a c tThis work explores the mechanisms by which a post injection can reduce unburned hydrocarbon (UHC) emissions in heavy-duty diesel engines operating at low-temperature combustion conditions. Post injections, small, close-coupled injections of fuel after the main injection, have been shown to reduce UHC in the authors' previous work. In this work, we analyze optical data from laser-induced fluorescence of both CH 2 O and OH and use chemical reactor modeling to better understand the mechanism by which post injections reduce UHC emissions. The results indicate that post-injection efficacy, or the extent to which a post injection reduces UHC emissions, is a strong function of the cylinder pressure variation during the post injection. However, the data and analysis indicate that the pressure and temperature rise from the post injection combustion cannot solely explain the UHC reduction measured by both engine-out and optical diagnostics. The fluid-mechanic, thermal, and chemical interaction of the post injection with the main-injection mixture is a key part of UHC reduction; the starting action of the post jet and the subsequent entrainment of surrounding gases are likely both important processes in reducing UHC with a post injection.

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Section: Introductionmentioning

confidence: 99%

Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine

O’Connor

Musculus

Pickett

2016

Combustion and Flame

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“…Some advantages of the Miller-Atkinson [1][2][3][4][5][6][7][8] cycle are given in [9,10] and we will not repeat the presentation here.…”

Section: Introductionmentioning

confidence: 99%

Elements of Cam’s Synthesis for a Distribution Mechanism for the Miller-Atkinson Cycle

Dragomir¹,

Mănescu²,

Stănescu

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. In this paper we present the synthesis of the cam for a distribution mechanism used for Miller-Atkinson cycle and described in previous works. The input data contain the angles at which the valve opens and closes, respectively, the dimensions of the main parts, the maximum displacement of the valve. and the law of motion of the valve. The authors consider that the law of motion of the valve is described by numerical values, even if in the simulation process they use analytical formulae for this displacement. The head of the valve is considered to be circular. A particular case of flat head of the valve is also described. The relative displacement of the lever and the valve is discussed in two hypotheses: symmetric position and asymmetric position of the contact point with respect to the axis of the valve. The contact between the head of the valve is assured by a cylindrical roller. The contact between the cam and the lever is considered with a roller tappet. In all cases the cam is obtained by numerical synthesis using a convenient angular degree. A great attention is paid to the convexity of the cam. The resulted cam is transformed in a convex one using the Jarvis March. The authors also perform a comparison between the theoretical profile of the cam and the profile of the convex cam. The reduced velocity and acceleration are obtained in all cases. Some aspects of the wear are discussed using the relative linear and angular velocities. The paper closes with a paragraph of conclusions.

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“…The VVA/VVT systems allow adequate flexibility in valve actuation to optimize cylinder charging and low-end torque with simultaneous improvements in fuel consumption and drivability [15]. Murata et al [10] demonstrated that ignition timing control of premixed diesel combustion can be realised by optimizing compressed gas temperature by adopting late IVC. At high-speed and intermediate load operation, Nevin et al…”

Section: Introductionmentioning

confidence: 99%

“…There is a multitude of VVT/VVA systems under development, including exhaust re-induction using late IVO (Intake Valve Opening) and late EVC (Exhaust Valve Closing) [7], exhaust re-breathing using a second exhaust valve event during the intake stroke [8,9], in-cylinder air out-flowing by late IVC (Intake Valve Closing) [9,10] and exhaust retention using early EVC and late IVO (also referred as NVO -Negative Valve Overlap) [11,12].…”

Section: Introductionmentioning

confidence: 99%

An investigation and evaluation of variable-valve-timing and variable-valve-actuation strategies in a diesel homogeneous charge compression ignition engine using three-dimensional computational fluid dynamics

Peng

Jia

2008

Proceedings of the Institution of Mechanical Engineers, Part D:

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A three-dimensional CFD modeling was carried out to investigate effects of VVT/VVA on gas exchange and fuel-air mixing processes in a diesel HCCI engine with early fuel injection. Four VVT/VVA strategies were conducted for this study: i) NVO strategy with fixed EVO and IVC timings but variable valve lifts -referred as NVO Strategy; ii) NVO strategy with fixed valve profiles but variable EVO and IVC timings -referred as EVO Strategy; iii) NVO strategy with fixed valve lifts and fixed EVO and IVC timings but variable EVO and IVC timings -referred as EVC Strategy; iv) VVA with just variable valve lifts -referred as VMAX Strategy. The results indicate that suitable NVO settings will enhance in-cylinder tumble and then increase turbulence intensity before compression-end, though the increased NVO has a negative contribution to swirl ratio. It was found that reducing valve lifts alone is not an efficient way to retain the residual gas, but the function of reduced valve lifts will become significantly obvious by combining it with increasing NVO. For the effect of NVO on in-cylinder temperature, longer NVO will not only increase in-cylinder temperature due to higher residual gas rate, but also improve the in-cylinder temperature homogeneity. Lowering the maximum valve lift or increasing NVO, the unmixed region of in-cylinder charge shrinks. The rich fuel region expands because of the high intake velocity and enhanced turbulence intensity. This is beneficial to the forming of global homogeneous charge. It has been noted from the current study, as the droplet distribution may be influenced more by the in-cylinder air motion caused by NVO when the average droplet size is smaller, it is recommended that future studies explore the effects of VVT/VVA on diesel HCCI mixing and combustion with various advanced fuel injection strategies.

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Achievement of Medium Engine Speed and Load Premixed Diesel Combustion with Variable Valve Timing

Cited by 54 publications

References 22 publications

Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine

Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine

Elements of Cam’s Synthesis for a Distribution Mechanism for the Miller-Atkinson Cycle

An investigation and evaluation of variable-valve-timing and variable-valve-actuation strategies in a diesel homogeneous charge compression ignition engine using three-dimensional computational fluid dynamics

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