Influence of Late Intake-Valve Opening on the S.I. Engine-Performance in Idle Condition

Badami, Marco; Marzano, Mario Rocco; Nuccio, Patrizio

doi:10.4271/960586

Cited by 10 publications

(6 citation statements)

References 9 publications

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“…This is clearly shown in Fig. 7, where the standard deviation of the pressure vs crank-angle appears to be lower, in correspondence to a smaller intake valve opening advance, and a better idle quality is obtained [5].…”

Section: Fluid Exchangementioning

confidence: 69%

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Historical Review of Variable Valve Actuation Systems

Nuccio¹,

Marzano²

2008

The International Conference on Applied Mechanics and Mechanica

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The internal combustion reciprocating engines that are usually employed in automotive applications need high torque at low revolution speeds to quickly increase car velocity without shifting gears. However, high power at top speed is required to obtain an adequate maximum speed as well as sufficient acceleration, through up-shifting. Designers can decide, according to different valve-timing diagrams, whether to improve torque at low speeds or power at top speeds. Unfortunately, both these improvements cannot be carried out at the same time, if the valve-timing diagram does not change with the engine revolution speed. Therefore, the current solutions for ordinary massproduced automotive engines are often a compromise between torque and power performance. A suitable choice of intake-valve and exhaust-valve timing, by means of Variable Valve Actuation (VVA), could instead satisfy both these requirements at the same time and even reduce fuel consumption and pollutant emissions. The aim of this review is to outline some of the most significant proposals over the last forty years as far as VVA systems are concerned.

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Section: Fluid Exchangementioning

confidence: 69%

“…Effects of the advanced IVO on the pressure standard deviation in idle conditions for an s.i. engine [5].…”

Section: Large Overlap Large Overlapmentioning

confidence: 99%

Historical Review of Variable Valve Actuation Systems

Nuccio¹,

Marzano²

2008

The International Conference on Applied Mechanics and Mechanica

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“…Badami et al [27] performed experiments on a 2-cylinder, 4-stroke, 594-cc, 7.5-CR, air-cooled engine. was to implement VVT (EIVC ) with the use of the secondary valve.…”

Section: Late Intake Valve Closing (Livc )mentioning

confidence: 99%

“…assembly between the cylinder head and the original intake manifold of the engine. The main purpose Badami et al [27] performed experiments on a 2-cylinder, 4-stroke, 594-cc, 7.5-CR, air-cooled engine. was to implement VVT (EIVC ) with the use of the secondary valve.…”

Section: Late Intake Valve Closing (Livc )mentioning

confidence: 99%

Review and analysis of variable valve timing strategies—eight ways to approach

Hong

Parvate-Patil

Gordon

2004

Proceedings of the Institution of Mechanical Engineers, Part D:

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In internal combustion engines, particularly for spark ignition (SI ) engines, valve events and their timings have a major influence on the engine's overall efficiency and its exhaust emissions. Because the conventional SI engine has fixed timing and synchronization between the camshaft and crankshaft, a compromise results between engine efficiency, performance, and its maximum power. By using variable valve timing ( VVT ) technology it is possible to control the valve lift, phase, and valve timing at any point on the engine map, with the result of enhancing the overall engine performance. To get full benefits from VVT, various types of mechanisms have been proposed and designed. Some of these mechanisms are in production and have shown significant benefits in improving engine performance. During the last two decades, remarkable developments have been seen in the field of VVT. This paper reviews the literature in the technology of intake and exhaust philosophies of VVT and their effects on the pressure-volume (PV ) cycle of the engine. A single-cylinder engine is simulated by the GT-Power software. The effects of different VVT philosophies from the simulations are analysed and compared to those of the literature reviewed.Keywords: variable valve timing ( VVT ), variable valve actuation ( VVA), valve overlap, exhaust gas recirculation (EGR) INTRODUCTIONResidual gas fraction ( RGF ) is controlled by the valve overlap and cannot be changed for various speeds and loads. The fixed-valve events of conventional cam-A major goal of engine manufacturers is to minimize specific fuel consumption and emissions from engines.controlled engines compromises the engine for better performance under all operating conditions. The inlet-valve One solution is by the independent actuation of the inlet and exhaust valves at any position of the piston, with timing is the most important parameter for optimizing the engine volumetric efficiency, whereas the exhaustno more need for a camshaft.A major disadvantage of conventional spark ignition valve timing controls the RGF, which reduces exhaust NO x emission. For the engine to operate efficiently and (SI ) engines results from the energy losses during the inhaling of the sub-atmospheric gases during the suction effectively over its entire operating range and conditions, the valve events should be able to vary with speed and stroke and the expelling of exhaust gases to the atmosphere during the exhaust stroke. These pumping losses depend load anywhere on the engine map. The present investigation undertakes the assessment of on the opening and closing position of the throttle valve. The losses are high when the throttle valve tends to close intake and exhaust philosophies for VVT. and are low at wide-open throttle. Thus, the pumping losses are inversely proportional with the engine load. Without a throttle valve, control of the air-fuel mixture 2 VALVE EVENTS OF CONVENTIONAL SI can be realized by variation of the intake valve-opening ENGINES period; therefore, variable valve timing ( VVT ) h...

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“…Idle benefits are caused by the smaller engine's ability to run at lower mean piston speeds (MPS). A minimum MPS of 1.9 m/s corresponding to 1000 rev/min was achieved while still maintaining adequate idle stability [35,36]. Lower idle speeds are achievable with further development, which would further reduce fuel consumption and emissions.…”

Section: Fuel Consumption and Co 2 Emissionsmentioning

confidence: 99%

The Feasibility of Downsizing a 1.25 Liter Normally Aspirated Engine to a 0.43 Liter Highly Turbocharged Engine

Attard¹,

Konidaris²,

Toulson³

et al. 2007

SAE Technical Paper Series

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In this paper, performance, efficiency and emission experimental results are presented from a prototype 434 cm 3 , highly turbocharged (TC), two cylinder engine with brake power limited to approximately 60 kW. These results are compared to current small engines found in today's automobile marketplace. A normally aspirated (NA) 1.25 liter, four cylinder, modern production engine with similar brake power output is used for comparison. Results illustrate the potential for downsized engines to significantly reduce fuel consumption while still maintaining engine performance. This has advantages in reducing vehicle running costs together with meeting tighter carbon dioxide (CO 2) emission standards. Experimental results highlight the performance potential of smaller engines with intake boosting. This is demonstrated with the test engine achieving 25 bar brake mean effective pressure (BMEP). Results are presented across varying parameter domains, including engine speed, compression ratio (CR), manifold absolute pressure (MAP) and lambda (λ). Engine operating limits are also outlined, with spark knock highlighted as the major limitation in extending the operating limits for this downsized engine.

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Influence of Late Intake-Valve Opening on the S.I. Engine-Performance in Idle Condition

Cited by 10 publications

References 9 publications

Historical Review of Variable Valve Actuation Systems

Historical Review of Variable Valve Actuation Systems

Review and analysis of variable valve timing strategies—eight ways to approach

The Feasibility of Downsizing a 1.25 Liter Normally Aspirated Engine to a 0.43 Liter Highly Turbocharged Engine

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