Improvements to a Four Cylinder Gasoline Engine Through the Fully Variable Valve Lift and Timing System UniValve®

Flierl, Rudolf; Gollasch, Daniel; Knecht, Andreas; Hannibal, Wilhelm

doi:10.4271/2006-01-0223

Cited by 36 publications

(16 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In Flierl et al, 5 such a variable valve timing and lift (VVTL) system is presented. A rocker arm with a working curve is placed between the cam and the standard roller cam follower.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and kinematic and dynamic analysis of a variable valve lift mechanism with general contact curve

Mihalcea

Stănescu

Popa

2014

Proceedings of the Institution of Mechanical Engineers, Part K:

View full text Add to dashboard Cite

In this paper, a new type of continuously variable valve lift (VVL) system is presented. The mechanism comprises a standard roller finger follower, the camshaft, and an intermediate rocker arm used between them. When the adjustment shaft rotates, the intermediate rocker arm is repositioned with respect to the cam and the roller of the rocker finger. This means that, when the rotation angle of the adjustment shaft is controlled, the valve lift height is also controlled. The intermediate rocker arm is equipped with a special developed contact surface, which is one of the novelties of this paper. The profile of the contact surface is analytically determined using the theory of the envelope curves. Using a certain cam profile, the kinematic analysis of the mechanism proceeds, resulting in the family of the valve lift laws. This paper also establishes the general conditions to design a variable valve timing (VVT) mechanism with continuous VVL and mechanical actuation. Numerical simulation shows that the mechanism continuously varies valve lift height and timing phases, while the valve's opening time remains constant. The last parts of the paper are dedicated to different aspects concerning the elastohydrodynamic lubrication and valve train dynamics. The study is performed by comparing the optimized cam and a standard harmonic one which achieves the same maximum displacement of the valve. The optimized cam ensures better safety in functioning, a smaller preload, leading to a greater oil film thickness, and not causing excessive deformations in the engine. The calculation model is a general one, and it may be applied to other mechanisms with similar configuration.

show abstract

“…In Flierl et al, 5 such a variable valve timing and lift (VVTL) system is presented. A rocker arm with a working curve is placed between the cam and the standard roller cam follower.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and kinematic and dynamic analysis of a variable valve lift mechanism with general contact curve

Mihalcea

Stănescu

Popa

2014

Proceedings of the Institution of Mechanical Engineers, Part K:

View full text Add to dashboard Cite

show abstract

“…A VVL system needs to integrate appropriate cam with different profiles and corresponding Maximum Valve Lift (MVL) for the optimal relationship between discharge coefficient and crank angle [11,12]. Compared to throttled operations, VVL could help to maintain a much higher absolute in-cylinder pressure (or lower vacuum) at the early intake stage.…”

Section: Introductionmentioning

confidence: 99%

An Investigation into In-Cylinder Tumble Flow Characteristics with Variable Valve Lift in a Gasoline Engine

Wang

Liu

Tan

et al. 2014

Flow Turbulence Combust

View full text Add to dashboard Cite

In this paper, the investigation into in-cylinder tumble flow characteristics with reduced Maximum Valve Lifts (MVL) is presented. The experimental work was conducted in a modified four-valve Spark-Ignition (SI) test engine, with optical accesses for measuring in-cylinder air motion in the vertical direction. Three different MVL of 6.8 mm, 4.0 mm and 1.7 mm were tested and Particle Image Velocimetry (PIV) was employed for those measurements. Measurement results were analysed by examining the tumble flow field, the tumble ratio variation and the fluctuating kinetic energy distribution. Meanwhile, a numerical analysis method for detecting the vortex centre was developed. From results of the vortex centre distribution, the cyclic variation of the in-cylinder flow was explored. The phase-averaged flow fields show that higher MVLs could produce stronger vertical flows which turn more toward to the piston top and finally are possible to form big scale tumble flow structure. Although lower MVLs create a higher tumble ratio when the piston is close to the Bottom Dead Centre (BDC), higher MVLs substantially produce higher tumble ratios when the piston is moving close to the Top Dead Centre (TDC). In terms of kinetic energy, lower MVLs result in higher values including higher total kinetic energy and higher fluctuating energy. Finally, the vortex centres results demonstrate lower MVLs could enhance cycle-to-cycle variation due to the weakened tumble vortex.

show abstract

“…The use of the independent inlet or exhaust valves actuation has been proposed in order to increase of the efficiency of the open, ideal cycle as well as effective efficiency and effective power of the spark-ignition engine [4,5,6]. Theoretical research of the systems with early inlet valve closing (EIVC) and early exhaust valve closing (EEVC) has been carried out.…”

Section: Introductionmentioning

confidence: 99%

Energy Aspects of the Si Engine Load Adjustment by Early Closing of Inlet or Exhaust Valve

Żmudka

Postrzednik

Przybyła

2016

Journal of KONES. Powertrain and Transport

View full text Add to dashboard Cite

The theoretical analysis of the SI engine load adjustment has been presented. The load especially in SI engine is highly dependent on the process of charge exchange. This process has significant impact on the effectiveness of an engine work because it is connected with the necessity of overcoming the flow resistance, then with the necessity of doing a work, so-called the charge exchange work. The flow resistance caused by throttling valve is especially high during part load operation. The open theoretical cycle has been assumed as a model of processes proceeding in the engine. Using fully variable inlet and exhaust valves timing the cycle can be realized e.g. according to two systems: system with early inlet valve closing (EIVC) and system with early exhaust valve closing (EEVC). Both systems have been analysed individually and comparatively with the open Seiliger-Sabathe cycle, which is theoretical cycle for the classical throttle governing of an engine load. Benefits resulting from application of the systems with independent inlet and exhaust valves control have been assessed on the basis of the selected parameters: a fuel dose, a cycle work, a charge exchange work and a cycle efficiency. The use of the analysed systems to governing of the SI engine load will enable to eliminate a throttling valve from inlet system and reduce the charge exchange work, especially within the range of part load operation. Decrease of the charge exchange work leads to increase of the internal and effective works, which results in increase of the effective efficiency of the spark ignition engine. Additionally, the EEVC enables realization of the internal EGR.

show abstract

Improvements to a Four Cylinder Gasoline Engine Through the Fully Variable Valve Lift and Timing System UniValve®

Cited by 36 publications

References 4 publications

Synthesis and kinematic and dynamic analysis of a variable valve lift mechanism with general contact curve

Synthesis and kinematic and dynamic analysis of a variable valve lift mechanism with general contact curve

An Investigation into In-Cylinder Tumble Flow Characteristics with Variable Valve Lift in a Gasoline Engine

Energy Aspects of the Si Engine Load Adjustment by Early Closing of Inlet or Exhaust Valve

Contact Info

Product

Resources

About