Simulation Tools for Development of Advanced Engine Braking and Variable Valve Actuation Systems

2002 ◽  
Author(s):  
John Schwoerer ◽  
Shengqiang Huang ◽  
Gregory Trzaska
Keyword(s):  
Simulation Tools ◽  
Variable Valve Actuation ◽  
Variable Valve ◽  
Actuation Systems ◽  
Valve Actuation

Analytical and Experimental Assessment of Some Novel Variable-Valve-Actuation Mechanisms

2010 ◽  
Vol 2 (2) ◽  
Author(s):  
Burak Gecim ◽  
Madhusudan Raghavan
Keyword(s):  
Test Results ◽  
Experimental Assessment ◽  
Variable Valve Actuation ◽  
Mechanical Variable ◽  
Experimental Works ◽  
Design Solutions ◽  
Variable Valve ◽  
Actuation Systems ◽  
Deactivation Mechanism ◽  
Valve Actuation

We describe our analytical and experimental works on three novel variable valve actuation systems. These include a mechanical variable-lift and duration concept, a hydraulic-lost-motion variable-lift system, and a valve-deactivation mechanism with unique features. These devices differ in their complexity and versatility but offer a spectrum of design solutions applicable to a range of products. The strengths and weaknesses of these different approaches are discussed and analyzed, and some test results are presented.

New mechanical variable valve actuation systems for motorcycle engines

2014 ◽  
Vol 229 (4) ◽  
pp. 716-734 ◽  
Author(s):  
Carmelina Abagnale ◽  
Mariano Migliaccio ◽  
Ottavio Pennacchia
Keyword(s):  
High Performance ◽  
Numerical Procedure ◽  
Valve Lift ◽  
Beneficial Effects ◽  
Variable Valve Actuation ◽  
Mechanical Variable ◽  
Set Up ◽  
Variable Valve ◽  
Actuation Systems ◽  
Valve Actuation

This paper summarizes the results of the design of new mechanical variable valve actuation systems, developed for high-performance motorcycle engines, at University of Napoli Federico II, Department of Industrial Engineering – Section Mechanics and Energy. After a synthetic recapitulation of the main variable valve-actuation methods and of the main beneficial effects on performance, emissions, and consumptions of the modern automotive engines on which they are currently employed, the paper presents the results of our mechanical variable valve actuation systems, born to be applied on a MotoMorini engine, as required by the company. The paper starts with the description of a first study concerning a very simple system, used just to set up a model to be used for further and more complex activities. The study has been conducted implementing a numerical procedure specifically designed to determine cam profile and kinematic and dynamic characteristics of the whole system, starting from some input data (as described later). The model has been validated against the conventional timing system using kinematic simulations. The work has evolved through three main steps leading to three types of variable valve actuation systems, all mechanical systems (as defined in literature and described later). Results of the numerical procedure verify the validity of the variable valve actuation systems, and particularly, the last one shows a complete performance in terms of lift, duration, and timing variation of valve-lift law. This paper reports results reachable with these simple systems that give good perspectives of use for a new two-wheel vehicle engine.

A New Valve Lift Control Technique in Electrohydraulic Variable Valve Actuation Systems

2010 ◽  
Author(s):  
Mohammad Pournazeri ◽  
Amir Khajepour ◽  
Amir Fazeli
Keyword(s):  
Control Valve ◽  
Operating Conditions ◽  
Valve Lift ◽  
Control Technique ◽  
Variable Valve Actuation ◽  
Actuation System ◽  
Lift Control ◽  
Variable Valve ◽  
Actuation Systems ◽  
Valve Actuation

Besides valve timings and opening duration control, several benefits could be achieved in engine operation if the valve actuation system could control the maximum valve displacement during a particular engine condition. Typically, in most electro-hydraulic variable valve actuation systems (VVA), the maximum valve lift along with valve opening/closing events are adjusted simultaneously by precise control of the spool travel in servo-valves. However, at high engine speeds, concurrent control of timings and peak valve lift becomes difficult and sometimes even impossible due to servo-valve response time limitations. In this paper, a new lift control technique is proposed using a control-valve located in the hydraulic supply line. Using this technique, it is possible to precisely control the valve lift even at high engine speeds. With this mechanism, the control-valve flow area could be adjusted using a low-speed actuator such as an electric motor. In contrast to conventional approaches, where maximum lift is repeatedly controlled within each cycle, valve lift in this technique can be adjusted after few engine cycles, thereby reducing control signal fluctuations and also eliminating the need for ultra-high-speed actuators. The proposed hydraulic VVA system is mathematically modeled, and a non-linear sliding mode controller is designed based on the derived equations. Finally, the performance of the proposed lift control technique is verified under different operating conditions.

Potential of the Variable Valve Actuation (VVA) Strategy on a Heavy Duty CNG Engine

2014 ◽  
Author(s):  
Mirko Baratta ◽  
Roberto Finesso ◽  
Daniela Misul ◽  
Ezio Spessa ◽  
Yifei Tong ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Operating Conditions ◽  
Intake Valve ◽  
Heavy Duty ◽  
Engine Emissions ◽  
Variable Valve Actuation ◽  
Cng Engine ◽  
Variable Valve ◽  
Working Point ◽  
Valve Actuation

The environmental concerns officially aroused in 1970s made the control of the engine emissions a major issue for the automotive industry. The corresponding reduction in fuel consumption has become a challenge so as to meet the current and future emission legislations. Given the increasing interest retained by the optimal use of a Variable Valve Actuation (VVA) technology, the present paper investigates into the potentials of combining the VVA solution to CNG fuelling. Experiments and simulations were carried out on a heavy duty 6-cylinders CNG engine equipped with a turbocharger displaying a twin-entry waste-gate-controlled turbine. The analysis aimed at exploring the potentials of the Early Intake Valve Closure (EIVC) mode and to identify advanced solutions for the combustion management as well as for the turbo-matching. The engine model was developed within the GT-Power environment and was finely tuned to reproduce the experimental readings under steady state operations. The 0D-1D model was hence run to reproduce the engine operating conditions at different speeds and loads and to highlight the effect of the VVA on the engine performance as well as on the fuel consumption and engine emissions. Pumping losses proved to reduce to a great extent, thus decreasing the brake specific fuel consumption (BSFC) with respect to the throttled engine. The exhaust temperature at the turbine inlet was kept to an almost constant value and minor variations were allowed. This was meant to avoid an excessive worsening in the TWC working conditions, as well as deterioration in the turbocharger performance during load transients. The numerical results also proved that full load torque increases can be achieved by reducing the spark advance so that a higher enthalpy is delivered to the turbocharger. Similar torque levels were also obtained by means of Early Intake Valve Closing strategy. For the latter case, negligible penalties in the fuel consumption were detected. Moreover, for a given combustion phasing, the IVC angle directly controls the mass-flow rate and thus the torque. On the other hand, a slight dependence on the combustion phasing can be detected at part load. Finally, the simulations assessed for almost constant fuel consumption for a wide range of IVC and SA values. Specific attention was also paid to the turbocharger group functioning and to its correct matching to the engine working point. The simulations showed that the working point on the compressor map can be optimized by properly setting the spark advance (SA) as referred to the adopted intake-valve closing angle. It is anyhow worth observing that the engine high loads set a constraint deriving from the need to meet the limits on the peak firing pressure (PFP), thus limiting the possibility to optimize the working point once the turbo-matching is defined.

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