Comparative study on the pumping losses between continuous variable valve lift (CVVL) engine and variable valve timing (VVT) engine

2018 ◽  
Vol 137 ◽  
pp. 710-720 ◽  
Author(s):  
Qingyu Li ◽  
Jingping Liu ◽  
Jianqin Fu ◽  
Xianjie Zhou ◽  
Cheng Liao
Keyword(s):  
Comparative Study ◽  
Continuous Variable ◽  
Valve Lift ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Variable Valve Lift ◽  
Variable Valve

A novel volumetric efficiency model for spark ignition engines equipped with variable valve timing and variable valve lift Part 1: model development

2016 ◽  
Vol 231 (2) ◽  
pp. 175-191 ◽  
Author(s):  
Amir Hasan Kakaee ◽  
Behrooz Mashadi ◽  
Mostafa Ghajar
Keyword(s):  
Experimental Data ◽  
Spark Ignition ◽  
Volumetric Efficiency ◽  
Valve Lift ◽  
Variable Valve Timing ◽  
Spark Ignition Engines ◽  
Valve Timing ◽  
Real Time Applications ◽  
Variable Valve Lift ◽  
Variable Valve

Estimation of the air charge and the volumetric efficiency is one of the most challenging tasks in the control of internal-combustion engines owing to the intrinsic complexity and the non-linearity of the gas flow phenomena. In particular, with emerging new technologies such as systems with variable valve timing and variable valve lift, the number of effective parameters increases greatly, making the estimation task more complicated. On the other hand, using a three-way catalyst converter needs strict control of the air-to-fuel ratio to around the stoichiometric ratio, and hence more accurate models are required for estimation of the air charge. Therefore, various models have been proposed in the literature for estimation of the volumetric efficiency and the air charge. However, they are either strictly based on physical first principles, making them impractical for conventional applications, or nearly fully empirical and need many experimental data for calibration. In this paper, using a novel approach, a new semiempirical model is proposed for estimation of the volumetric efficiency, which is calibrated with very few experimental data and can be used easily for real-time applications. In addition to the valve timings, the engine speed and the intake manifold pressure, the inlet valve lift is also considered as the model input. The generalizability of the model is proved by applying it to estimate the volumetric efficiency of six different engines. Furthermore, a systematic approach is taken to simplify the proposed model and to strengthen its prediction capability. The result is a simple, practical and generalizable model which can be used for various spark ignition engines, can be trained with very few data and can be utilized for estimating accurately the volumetric efficiency in real-time applications.

scholarly journals FEASIBILITY OF BACKFIRE CONTROL AND PERFORMANCE USING CHANGES OF VALVE OVERLAP PERIOD FOR A HYDROGEN-FUELED ENGINE WITH EXTERNAL MIXTURE

2009 ◽  
Vol 12 (14) ◽  
pp. 77-85
Author(s):  
Cong Thanh Huynh ◽  
Kang Joon-Kyoung ◽  
Noh Ki-Cholo ◽  
Lee Jong-Tai ◽  
Mai Xuan Pham
Keyword(s):  
High Efficiency ◽  
Engine Performance ◽  
Continuous Variable ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Performance Loss ◽  
Wide Range ◽  
And Performance ◽  
Variable Valve ◽  
Valve Overlap

The development of a hydrogen-fueled engine using an external mixture (e.g., using port injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing (MCVVT) system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. In experiments, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.25 and 1.2. The results showed that the research engine with the MCVVT system has similar performance to a conventional engine, and is especially effective in controlling the valve overlap period. The obtained results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a H engine. Also, a method for compensating performance loss due to shortened valve overlap period is recommended.

scholarly journals Computational studies of the influence of variable valve timing on the performance of a gas engine with Miller’s thermodynamic cycle

2021 ◽  
Vol 2061 (1) ◽  
pp. 012066
Author(s):  
K V Milov
Keyword(s):  
Internal Combustion Engines ◽  
Computer Modelling ◽  
Thermodynamic Cycle ◽  
Valve Lift ◽  
Variable Valve Timing ◽  
Miller Cycle ◽  
Valve Timing ◽  
Gas Engine ◽  
Lift Height ◽  
Variable Valve

Abstract Current development trends in the field of internal combustion engines aim at regulating all processes of the engine and individual units. A converted diesel to gas engine with Miller thermodynamic cycle is more energy efficient at partial loads than a gas engine with Otto thermodynamic cycle. The Miller cycle engine with variable valve timing and valve lift has been investigated to improve performance and energy efficiency across the load range. The aim of the work is to study the influence of the displacement of the valve timing phases of the intake and exhaust camshafts and the valve lift height on the performance of the gas engine with the Miller cycle. Computer modelling was based on data obtained from the full-scale experiment on the gas engine with the Miller thermodynamic cycle.

Optimal Design of Worm Gear System Usage in CVVL for Automobiles

2013 ◽  
Author(s):  
Nogill Park ◽  
Jonghyeon Sohn ◽  
Gyeangmyeang Baek ◽  
Chunghan Oh
Keyword(s):  
Error Function ◽  
Transmission Error ◽  
Continuous Variable ◽  
Worm Gear ◽  
Gear System ◽  
Valve Lift ◽  
Variable Valve Lift ◽  
Variable Valve ◽  
Motor Drive System ◽  
Worm Drive

Gearing with a ZK worm and an involute helical gear is used in the motor drive system of automotive continuous variable valve lift (CVVL) because of production cost. Since the geared system does not satisfy the meshing condition, transmission error (TE) and teeth interference (TI) are inevitable. This paper introduces a method for reducing TE and eliminating TI. Transmission error function is derived mathematically and used in checking TI. The first prototype for an automobile shows a lot of NVH problem, which is simply combined by coinciding with the helix/lead angles of two gears at the pitch point. By an optimal process with alternating the pressure and helix angles of worm gear system, an prototype of CVVL worm drive of which NVH problem is acceptably solved is designed.

Development of a Motorcycle Engine with a Three-dimensional Cam for Continuous Variable Valve Lift and Timing Mechanism

2008 ◽  
Vol 1 (1) ◽  
pp. 1357-1365 ◽  
Author(s):  
Isato Taki ◽  
Muneaki Nakamura ◽  
Kenjiro Nakama ◽  
Kazutoshi Takahashi ◽  
Kosaku Yamauchi
Keyword(s):  
Three Dimensional ◽  
Continuous Variable ◽  
Valve Lift ◽  
Timing Mechanism ◽  
Variable Valve Lift ◽  
Variable Valve ◽  
Motorcycle Engine

Controlling Backfire Using Changes of the Valve Overlap Period for a Hydrogen-Fueled Engine Using an External Mixture

2007 ◽  
Author(s):  
T. C. Huynh ◽  
J. K. Kang ◽  
K. C. Noh ◽  
Jong T. Lee ◽  
J. A. Caton
Keyword(s):  
High Efficiency ◽  
Engine Performance ◽  
Continuous Variable ◽  
Operating Conditions ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Wide Range ◽  
Timing System ◽  
Variable Valve ◽  
Valve Overlap

The development of a hydrogen-fueled engine using an external mixture (e.g., using port or manifold fuel injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period while maintaining or improving engine performance. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. By using this research engine, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.3 and 1.2. The results showed that the developed hydrogen-fueled research engine with the mechanical continuous variable valve timing system has similar performance to a conventional engine with fixed valve timings, and is especially effective in controlling the valve overlap period. Backfire occurrence is reduced with a decrease of the valve overlap period, and is also significantly decreased even under operating conditions with the same volumetric efficiency. These results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a hydrogen-fueled engine while maintaining or improving performance.

Controlling Backfire for a Hydrogen-Fueled Engine Using External Mixture Injection

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
T. C. Huynh ◽  
J. K. Kang ◽  
K. C. Noh ◽  
Jong T. Lee ◽  
J. A. Caton
Keyword(s):  
High Efficiency ◽  
Engine Performance ◽  
Continuous Variable ◽  
Operating Conditions ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Wide Range ◽  
Timing System ◽  
Variable Valve ◽  
Valve Overlap

The development of a hydrogen-fueled engine using external mixture injection (e.g., using port or manifold fuel injection) with high efficiency and high power is dependent on the control of backfire. This work has developed a method to control backfire by reducing the valve overlap period while maintaining or improving engine performance. For this goal, a single-cylinder hydrogen-fueled research engine with a mechanical continuous variable valve timing system was developed. This facility provides a wide range of valve overlap periods that can be continuously and independently varied during firing operation. By using this research engine, the behavior of backfire occurrence and engine performance are determined as functions of the valve overlap period for fuel-air equivalence ratios between 0.3 and 1.2. The results showed that the developed hydrogen-fueled research engine with the mechanical continuous variable valve timing system has similar performance to a conventional engine with fixed valve timings, and is especially effective in controlling the valve overlap period. Backfire occurrence is reduced with a decrease in the valve overlap period, and is also significantly decreased even under operating conditions with the same volumetric efficiency. These results demonstrate that decreasing the valve overlap period may be one of the methods for controlling backfire in a hydrogen-fueled engine while maintaining or improving performance.

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