A Review of Variable Engine Valve Timing

Gray, Charles L.

doi:10.4271/880386

Cited by 95 publications

(25 citation statements)

References 2 publications

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“…3) This rotation resulting in additional rotation for the sun gear, which is connected with the camshaft, according to the following equation 3 …”

Section: The Methods Of Operationmentioning

confidence: 99%

“…In internal combustion engines, variable valve timing (VVT), also known as variable valve actuation (VVA), is a generalized term used to describe any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine [1][2][3][4][5][6]. The (VVT) system allows the lift, duration or timing (in various combinations) of the intake and/or exhaust valves to be changed while the engine is in operation, which have a significant impact on engine performance and emissions.…”

Section: Introductionmentioning

confidence: 99%

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Gear Drive Mechanism for Continuous Variable Valve Timing of IC Engines

Ghazal¹,

Dado²

2013

ENG

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Continuous variable valve actuating (CVVA) technology provides high potential in achieving high performance, low fuel consumption and pollutant reduction. To get full benefits from (CVVT) 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. In this investigation a newly designed gear drive mechanism that controls the intake valve opening (IVO) and closing (IVC) angles is studied. The control scheme is based on maximizing the engine brake power (P) and specific fuel consumption (BSFC) at any engine speed by continuously varying the phase between the cam shaft angle and the crank shaft angle. A single-cylinder engine is simulated by the "LOTUS" software to find out the optimum phase angle for maximum power and minimum fuel consumption at a given engine speed. The mechanism is a planetary gear drive designed for precise and continuous control. This mechanism has a simple design and operation conditions which can change the phase angle without limitation.

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“…3) This rotation resulting in additional rotation for the sun gear, which is connected with the camshaft, according to the following equation 3 …”

Section: The Methods Of Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gear Drive Mechanism for Continuous Variable Valve Timing of IC Engines

Ghazal¹,

Dado²

2013

ENG

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“…Nevertheless, retarding the cam timing have significant influence on the combustion stability. More details can be found in (Gray, 1988;Ma, 1988;Leone et al, 1996;Stein and Galietti, 1995;Stefanopoulou et al, 2000;Jankovic et al, 1998). Table 1 illustrates the sought after NO x emission reduction when the Variable Cam Timing (VCT) actuators are used (more details can be found in (Le Solliec et al, 2007)).…”

Section: Introductionmentioning

confidence: 99%

“…In several seminal papers (Gray, 1988;Ma, 1988;Leone et al, 1996;Stein and Galietti, 1995), it was demonstrated that optimization and realtime control of cam timing in an engine equipped with a dual equal camshaft timing phaser could help reduce the unburned hydrocarbons (HC) and oxides of nitrogen (NO x ). In particular, by retarding the cam timing, a large part of combustion products, which would otherwise be expelled during the exhaust stroke, are retained in the cylinder during the subsequent intake stroke.…”

Section: Introductionmentioning

confidence: 99%

Experimental Control of Variable Cam Timing Actuators

Chauvin

Petit

2007

IFAC Proceedings Volumes

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In this paper, we propose a control scheme for the position of Variable Cam Timing (VCT) actuators. We take into account the observation by (Genç et al., 2001) that these actuators feature a significant nonlinearity, but we use a different approach. We perform a model reduction of mechanics, pressure, flows and balance equations. It serves to design an observer used in a motion planning strategy that is ultimately complemented by a tracking controller. Supportive vehicle experimental results are presented.

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“…Variable valve timing (VVT) mechanisms have the potential to improve fuel economy, performance and emission levels of gasoline engines [3]. The particular VVT mechanism investigated in this paper is variable camshaft timing.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Changing Fuel Path Dynamics in Twin-Independent Variable Camshaft Timing Engines

Genc

Ford

Glover

et al. 2002

SAE Technical Paper Series

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The effect of a variable camshaft timing (VCT) disturbance on air-to-fuel ratio (AFR) signal is investigated for a twin-independent (TI) VCT engine. Different types of VCT disturbances on AFR signal are investigated. Gaseous fuel experiments are performed in addition to conventional petrol fuel experiments to show that not all the transient VCT disturbances acting on AFR are due to changes in air path dynamics. Experiments show that varying exhaust valve closing (EVC) timing has a significant effect on the air path dynamics and is an important cause of transient AFR deviations. However varying EVC does not affect the fuel puddle significantly. On the other hand varying inlet valve opening (IVO) timing has a strong effect on the fuel puddle size and is also an important cause of transient AFR deviations. Thus for superior transient AFR control in TI-VCT engines, it is essential to model not only the effects of valve timings on air path dynamics but also on the fuel path dynamics.

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A Review of Variable Engine Valve Timing

Cited by 95 publications

References 2 publications

Gear Drive Mechanism for Continuous Variable Valve Timing of IC Engines

Gear Drive Mechanism for Continuous Variable Valve Timing of IC Engines

Experimental Control of Variable Cam Timing Actuators

Experimental Investigation of Changing Fuel Path Dynamics in Twin-Independent Variable Camshaft Timing Engines

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