Design of a New Mechanical Variable Valve Actuation System for Motorcycle Engines

2012 ◽  
Author(s):  
Carmelina Abagnale ◽  
Mariano Migliaccio ◽  
Ottavio Pennacchia
Keyword(s):  
High Performance ◽  
Numerical Procedure ◽  
Valve Lift ◽  
Variable Valve Actuation ◽  
Actuation System ◽  
Mechanical Variable ◽  
System 2 ◽  
Variable Valve ◽  
System 1 ◽  
Valve Actuation

This paper deals with design and manufacturing of a mechanical variable valve actuation (VVA) system, developed as part of a MUR financed research project concerning the realization of a high performance motorcycle engine, through a partnership of Moto Morini (Bologna), Dell’Orto (Milano), Istituto Motori - CNR (Napoli) and DiME (Department of Mechanical Engineering and Energetics) – University of Napoli Federico II. After a synthetic description of the main variable valve actuation methods currently employed, the paper presents the results of our mechanical VVA system, consisting of three main elements: cam, main rocker arm with fixed fulcrum and secondary rocker arm with mobile fulcrum. This VVA system (system 1) enables valve lift variation by a simple translation of one of the three elements (the intermediate one). 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 the following input data: rocker arm geometry, relative positions and inertial data of elements, spring stiffness and preloading, camshaft speed and valve lift law. The model has been validated against the conventional timing system using kinematic simulations. Results of the numerical procedure verify the validity of the VVA system, capable of a valve lift variation, with a limited acceleration. Starting from the numerical results, we have developed a new mechanical variable valve actuation system (system 2): it consists of the same three elements used previously, but they are connected in a different way. The newer system enables more general lift profile distributions with a similar geometric complexity. The activity has been extended to research for a new solution (always a mechanical system), capable to allow inlet valves complete closing and timing and duration variation (system 3). This paper reports results reachable with the simplest system 1, that gives better perspectives of use for a new two-wheel vehicle engine.

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 mechanical variable valve actuation system for motorcycle engines

2009 ◽  
Author(s):  
C. Abagnale ◽  
S. Caruso ◽  
A. Iorio ◽  
M. Migliaccio ◽  
O. Pennacchia
Keyword(s):  
Variable Valve Actuation ◽  
Actuation System ◽  
Mechanical Variable ◽  
Variable Valve ◽  
Valve Actuation

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.

scholarly journals Research on Homogeneous Charge Compression Ignition Combustion of Intake Port Exhaust Gas Recirculation Based on Cam Drive Hydraulic Variable Valve Actuation Mechanism

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 438
Author(s):  
Linghai Han ◽  
Jiaquan Duan ◽  
Dingchao Qian ◽  
Yanfeng Gong ◽  
Yaodong Wang ◽  
...  
Keyword(s):  
Engine Speed ◽  
Valve Lift ◽  
Intake Port ◽  
Cyclic Variation ◽  
Response Characteristics ◽  
Variable Valve Actuation ◽  
Hcci Combustion ◽  
Variation Range ◽  
Variable Valve ◽  
Valve Actuation

The thermal efficiency of an efficient gasoline engine is only about 40% and it will produce a large number of harmful products. Curbing harmful emissions and enhancing thermal efficiency have always been the goals pursued and emission regulations are also being tightened gradually. As one of the main consumers of fossil fuels, automobile engines must further reduce fuel consumption and emissions to comply with the concept of low-carbon development, which will also help them compete with electric vehicles. Homogeneous charge compression ignition (HCCI) combustion combined with variable valve actuation (VVA) technology is one of the important ways to improve engine emissions and economy. HCCI combustion based on VVA can only be realized at small and medium loads. The actual application on the entire vehicle needs to be combined with spark ignition (SI) combustion to achieve full working condition coverage. Therefore, HCCI combustion needs fast valve response characteristics; however, the valve lift and timing of the existing VVA mechanisms are mostly controlled separately, resulting in poor valve response. In order to solve this problem, the cam driven hydraulic variable valve actuation (CDH-VVA) mechanism was designed. The valve lift and timing can be adjusted at the same time and the switching of valve lift and timing can be completed in 1~2 cycles. A set of combustion mode switching data is selected to show the response characteristics of the CDH-VVA mechanism. When switching from spark ignition (SI) to HCCI, it switches to HCCI combustion after only one combustion cycle and it switches to stable HCCI combustion after two combustion cycles, which proves the fast response characteristics of the CDH-VVA mechanism. At the same time, the CDH-VVA mechanism can form the intake port exhaust gas recirculation (EGR), as one type of internal EGR. This paper studies the HCCI combustion characteristics of the CDH-VVA mechanism in order to optimize it in the future and enable it to realize more forms of HCCI combustion. At 1000 rpm, if the maximum lift of the exhaust valve (MLEV) is higher than 5.0 mm or lower than 1.5 mm, HCCI combustion cannot operate stably, the range of excess air coefficient (λ) is largest when the MLEV is 4.5 mm, ranging from 1.0~1.5. Then, as the MLEV decreases, the range of λ becomes smaller. When the MLEV drops to 1.5 mm, the range of λ shortens to 1.0~1.3. The maximum value of the MLEV remains the same at the three engine speeds (1000 rpm, 1200 rpm and 1400 rpm), which is 5.0 mm. The minimum value of the MLEV gradually climbs as the engine speed increase, 1000 rpm: 1.5 mm, 1200 rpm: 2.0 mm, 1400 rpm: 3.0 mm. With the increase of engine speed, the range of indicated mean effective pressure (IMEP) gradually declines, 3.53~6.31 bar (1000 rpm), 4.11~6.75 bar (1200 rpm), 5.02~6.09 bar (1400 rpm), which proves that the HCCI combustion loads of the intake port EGR are high and cannot be extended to low loads. The cyclic variation of HCCI combustion basically climbs with the decrease of the MLEV and slightly jumps with the increase of the engine speed. At 1000 rpm, when the MLEV is 5.0 mm, the cyclic variation range is 0.94%~1.5%. As the MLEV drops to 1.5 mm, the cyclic variation range rises to 3.5%~4.5%. Taking the maximum value of the MLEV as an example, the cyclic variation range of 1000 rpm is 0.94%~1.5%, 1200 rpm becomes 1.5%~2.3% and 1400 rpm rises to 2.0%~2.5%.

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.

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