The Synthesis and Analysis of Variable-Valve-Timing Mechanisms for Internal-Combustion Engines

Abstract Since shifting to electric vehicles as a countermeasure against global warming is not always easy to complete, the hybrid car has been considered as another possible solution. However, based on the calculation of total CO2 emissions, all hybrid cars which will constitute 90% of all cars are expected to be equipped with an internal combustion engine even after 2030. Therefore, further efficiency improvement of the internal combustion engine is necessary. One of the key factors is the variable valve timing and variable lift with the 3D cam mechanism. Since conventional technology uses a complicated link mechanism and servo motor control, this leads a problem to set into small cars or motorcycles because they cannot afford to install the variable valve timing and variable lift with cam mechanism. To solve this problem, a cam shape with a three-dimensional curved surface has been proposed. In order to create this shape, the machining method for non-axisymmetric curved surface turning (NACS-Turning) is required. To build the new system, our research group has proposed a new machining method using a driven type rotary tool and a linear motor driven moving table to enable to achieve NACS-Turning. In this new system, a new tool rotation axis (B axis) is adopted to synchronize its rotational position with the rotational position of the spindle (C axis) holding the workpiece, the X1-, X2-, and Z-Axis positions in total. In this paper, the new hardware configuration is proposed to overcome the present machining accuracy.

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Variable Valve Timing Scheduling in a 4-Stroke Internal Combustion Cylinder Utilizing Artificial Neural Networks

Advances in Science and Technology – Research Journal ◽

10.12913/22998624/75968 ◽

2017 ◽

Vol 11 (3) ◽

pp. 114-121 ◽

Cited By ~ 1

Author(s):

Sepehr Bapiri ◽

Omid Chaghaneh ◽

Hossein Ghomashi

Keyword(s):

Neural Networks ◽

Artificial Neural Networks ◽

Internal Combustion ◽

Variable Valve Timing ◽

Valve Timing ◽

Artificial Neural ◽

Variable Valve

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

Journal of Physics Conference Series ◽

10.1088/1742-6596/2061/1/012066 ◽

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.

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Linear Parameter-Varying Model of an Electro-Hydraulic Variable Valve Actuator for Internal Combustion Engines

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4037286 ◽

2017 ◽

Vol 140 (1) ◽

Cited By ~ 7

Author(s):

Huan Li ◽

Ying Huang ◽

Guoming Zhu ◽

Zheng Lou

Keyword(s):

Internal Combustion Engines ◽

Internal Combustion ◽

Combustion Engines ◽

Time Varying ◽

Linear Parameter ◽

Linear Parameter Varying ◽

Varying Parameters ◽

Operational Conditions ◽

Time Varying Parameters ◽

Variable Valve

This paper presents a novel linear parameter-varying (LPV) model of an electro-hydraulic variable valve actuator (EHVVA) for internal combustion engines that is capable of continuously varying valve timing with dual-lift. The dual-lift is realized mechanically through a hydraulic lift control sleeve; valve opening (VO) terminal and closing seating velocities are regulated using a top or bottom snubber; and opening and closing timings, as well as lift profile area, are controlled by the valve actuation timing and hydraulic supply pressure. First, nonlinear mathematical system model is developed based on the Newton's law, orifice flow equation, and fluid constitutive law, where the fluid dynamics of the actuation solenoid valve, actuation piston, passages, and orifices, that influence the engine valve profile, are considered in detail. Second, to have an LPV control-oriented model, the order of nonlinear model is reduced and subsequently transformed into an LPV model with minimal deviation by carefully considering the system nonlinearities, time delay, and time-varying parameters. Calibration and validation experiments for both nonlinear and LPV models were performed on the test bench under different operational conditions. The key time-varying parameters, the time constant of the actuation piston top pressure and the discharge coefficient, are highly nonlinear as functions of temperature-sensitive fluid viscosity and are determined using the test data through the least-squares optimization. With the identified and calibrated model parameters, simulation results of both nonlinear and LPV models are in good agreement with the experimental ones under different operational conditions.

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Friction and Pumping Losses Estimation in Flex Internal Combustion Engines with Variable Valve Actuation System Using Chamber Pressure Measurement

10.4271/2012-36-0363 ◽

2012 ◽

Cited By ~ 1

Author(s):

Lucymara R. Alvarenga ◽

Marcela E. Vianna ◽

Marcio C. Pierobom ◽

Rodrigo V.G. Andrade

Keyword(s):

Pressure Measurement ◽

Internal Combustion Engines ◽

Internal Combustion ◽

Chamber Pressure ◽

Combustion Engines ◽

Variable Valve Actuation ◽

Actuation System ◽

Variable Valve ◽

Valve Actuation

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Miller Cycle Analysis Using EGM

ASME 2005 Internal Combustion Engine Division Fall Technical Conference (ICEF2005) ◽

10.1115/icef2005-1110 ◽

2005 ◽

Author(s):

Bernardo Ribeiro ◽

Jorge Martins

Keyword(s):

Heat Transfer ◽

Entropy Generation ◽

Compression Ratio ◽

Internal Combustion Engines ◽

Combustion Engines ◽

Miller Cycle ◽

Valve Timing ◽

Entropy Generation Minimization ◽

Flow And Heat Transfer ◽

Variable Valve

The Entropy Generation Minimization (EGM) method is based on the analysis by three sciences (thermodynamics, fluid flow and heat transfer) of the different processes that may occur in a system or in an equipment. Herein the EGM method is applied to internal combustion engines to determine the entropy generation caused by different processes. A model incorporating entropy generation calculations is used to assess various engines configurations. Otto cycle was tested and Variable Valve Timing (VVT) and Variable Compression Ratio (VCR) were applied so thermodynamic benefits could be tested and evaluated. With the referred model, the Miller cycle variables are analyzed in order to establish the best working conditions of an engine under a certain load. The intake and exhaust valve timing, combustion start, compression ratio adjustment and heat transfer are the variables for which a best working condition is determined based on the minimization of the entropy generation of the several engine processes.

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