Diesel engine optimization and exhaust thermal management by means of variable valve train strategies

Due to the need to achieve a fast warm-up of the after-treatment system in order to fulfill the pollutant emission regulations, a growing interest has arisen to adopt variable valve timing technology for automotive engines. Several variable valve timing strategies can be used to achieve an increment in the after-treatment upstream temperature by increasing the residual gas amount. In this study, a one-dimensional gas dynamics engine model has been used to carry out a simulation study comparing several exhaust variable valve actuation strategies. A steady-state analysis has been done in order to evaluate the potential of the different strategies at different operating points. Finally, the effect on the after-treatment warm-up, fuel economy and pollutant emission levels was evaluated over the worldwide harmonized light vehicles test cycle. As a conclusion, the combination of an advanced exhaust (early exhaust valve opening and early exhaust valve closing) and a delayed intake (late intake valve opening and late intake valve closing) presented the best trade-off between exhaust temperature increment and fuel consumption, which achieved a mean temperature increment during low-speed phase of the worldwide harmonized light vehicles test cycle of 27 °C with a fuel penalty of 6%. The exhaust valve re-opening technique offers a worse trade-off. However, the exhaust valve re-opening leads to lower nitrogen oxide (29% less) and carbon monoxide (11% less) pollutant emissions.

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PENCAPAIAN PERFORMA PADA KATUP VARIABEL TIMING FIXED TIMING UNTUK MESIN YANG OPTIMAL

Jurnal Teknik Industri ◽

10.22219/jtiumm.vol11.no1.68-74 ◽

2012 ◽

Vol 11 (1) ◽

pp. 68

Author(s):

KETUT ASTAWA

Keyword(s):

Engine Performance ◽

Variable Valve Timing ◽

Intake Valve ◽

Valve Timing ◽

Static Test ◽

Load Transmission ◽

Valve Opening ◽

Efficient Machine ◽

Hc Emissions ◽

Variable Valve

Problems will be discussed in this research is how differences in exhaust emissions generatedby engine with variable valve timing and valve timing on a fixed volume of motor vehiclecylinder 1300 cc. Variable valve timing technology, which is set when opening and closingthe intake valve (intake valve) electronic fuel according to engine conditions. This will makemixing air and fuel that enters into an efficient machine that will produce great power, fueleconomy and low emissions. Research emissions (CO, CO2, HC, O2) was performedwith dynamictesting, where the vehicle in a state of the load lifted and given transmission. Unlikethe testing generally performed with a static test, in which the vehicle is at rest and without aload. This test is performed to determine how the condition of exhaust gases when the vehicledynamic (analogous to the vehicle running). In general, machines with variable valve timingto produce better emissions than engines with fixed valve timing. The higher the spin machineand load transmission system will result in CO and HC emissions are decreased and O2 andCO2 increased. Engine with variable valve timing control the suction valve opening times toachieve optimum engine performance at various driving conditions. And set out the engineoutput as needed.

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Flow Field Parametric Interpolation Using a Proper Orthogonal Decomposition: Application to the Variable Valve Timing Effect on a Tumble In-cylinder Miller Engine Mean Flow

Energies ◽

10.3390/en14175324 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5324

Author(s):

Marcellin Perceau ◽

Philippe Guibert ◽

Stéphane Guilain

Keyword(s):

Velocity Field ◽

Input Parameter ◽

Orthogonal Decomposition ◽

Variable Valve Timing ◽

Intake Valve ◽

Valve Timing ◽

Mean Velocity ◽

The Mean ◽

Variable Valve ◽

Proper Orthogonal

The current article presents a method to reconstruct the mean velocity field of a cyclic flow for an input parameter value that has not been measured, allowing for the number of tests to be reduced. It is applied to the tumble flow of a gasoline engine following a Miller cycle. New engines often include variable valve timing (VVT) systems to maximize the efficiency of such over-expanded cycles for different operating points. The reconstruction was thus carried out using different offset values of the intake valve lift timing. Experimental data were collected from a transparent engine in an early intake valve closing (EIVC) configuration using particle image velocimetry (PIV). The mean velocity field reconstruction was based on the interpolation of the proper orthogonal decomposition (POD) coefficients. The accuracy of the method was evaluated at different points by comparing the interpolated and the measured flow fields. The accuracy was estimated by calculating the error in the rotation rate of the tumble and the position of its center of rotation. The new mean velocity field set allowed for the position of the tumble’s center of rotation to be closely tracked according to the input parameter and a rotation rate map to be made. Some results on Miller’s cycle could thus be found and the data generated could guide future developments.

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A Cam-Based Electro-Hydraulic Variable Valve Timing System for Pneumatic Hybrid Engines

Volume 13: New Developments in Simulation Methods and Software for Engineering Applications; Safety Engineering, Risk Analysis and Reliability Methods; Transportation Systems ◽

10.1115/imece2009-10531 ◽

2009 ◽

Cited By ~ 1

Author(s):

Mohammad Pournazeri ◽

Amir Fazeli ◽

Amir Khajepour

Keyword(s):

Valve Train ◽

Variable Valve Timing ◽

Valve Timing ◽

System A ◽

Timing System ◽

Valve Opening ◽

And Performance ◽

High Flexibility ◽

Variable Valve ◽

And Control

In this work, a new type of cam-based variable valve timing system has been proposed based on the “lost motion” principle. Using this mechanism, the problems with the valve transition time and control complexity which are still serious concerns for camless valve train systems are solved. This mechanism not only allows the engine to work at different modes of operation as an air hybrid engine but also enables it for continuous torque management. In this system, the control methodology utilizes a cam position feedback to control the valve opening timing. A combination of hydraulic and mechanical systems was utilized to offer high flexibility and robustness in the engine valve control system. A zero dimensional analysis is also conducted to evaluate the functionality and performance of the proposed system.

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The tuning of a small four-stroke spark ignition engine for flexible valve timings through numerical approach

MATEC Web of Conferences ◽

10.1051/matecconf/201925504004 ◽

2019 ◽

Vol 255 ◽

pp. 04004

Author(s):

M. Haziq Adham Rosli ◽

M. Razali Hanipah ◽

Maurice Kettner

Keyword(s):

Combustion Engine ◽

Engine Performance ◽

Numerical Approach ◽

Spark Ignition Engine ◽

Variable Valve Timing ◽

Intake Valve ◽

Valve Timing ◽

Engineering Research ◽

Numerical Assessment ◽

Variable Valve

Variable valve timing has been implemented by various manufacturers to improve internal combustion engine performance while operating at wide speed and load ranges. A novel flexible valve timing system for a small four-stroke engine is currently under development by Automotive Engineering Research Group (AERG) in Universiti Malaysia Pahang (UMP). In this paper, a comprehensive intake and exhaust tuning for the flexible variable valve timing is presented. A numerical assessment has been conducted through one dimensional engine modelling and simulation using validated model. There are eight valve timing configurations investigated for the tuning for three main speed regions. The simulation shows a positive and significant impact to the engine performance in three approaches; namely late intake valve closing, early intake valve closing and late exhaust valve closing. These approaches sufficiently covered the whole range of engine speeds for optimum engine operational performance.

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Implementing variable valve actuation on a diesel engine at high-speed idle operation for improved aftertreatment warm-up

International Journal of Engine Research ◽

10.1177/1468087419880639 ◽

2019 ◽

Vol 21 (7) ◽

pp. 1134-1146

Author(s):

Kalen R Vos ◽

Gregory M Shaver ◽

Mrunal C Joshi ◽

James McCarthy

Keyword(s):

Particulate Matter ◽

High Speed ◽

Exhaust Valve ◽

Exhaust Gas ◽

Warm Up ◽

Aftertreatment System ◽

Idle Speed ◽

Variable Valve Actuation ◽

Brake Mean Effective Pressure ◽

Valve Opening

Aftertreatment thermal management is critical for regulating emissions in modern diesel engines. Elevated engine-out temperatures and mass flows are effective at increasing the temperature of an aftertreatment system to enable efficient emission reduction. In this effort, experiments and analysis demonstrated that increasing the idle speed, while maintaining the same idle load, enables improved aftertreatment “warm-up” performance with engine-out NOx and particulate matter levels no higher than a state-of-the-art thermal calibration at conventional idle operation (800 rpm and 1.3 bar brake mean effective pressure). Elevated idle speeds of 1000 and 1200 rpm, compared to conventional idle at 800 rpm, realized 31%–51% increase in exhaust flow and 25 °C–40 °C increase in engine-out temperature, respectively. This study also demonstrated additional engine-out temperature benefits at all three idle speeds considered (800, 1000, and 1200 rpm, without compromising the exhaust flow rates or emissions, by modulating the exhaust valve opening timing. Early exhaust valve opening realizes up to ~51% increase in exhaust flow and 50 °C increase in engine-out temperature relative to conventional idle operation by forcing the engine to work harder via an early blowdown of the exhaust gas. This early blowdown of exhaust gas also reduces the time available for particulate matter oxidization, effectively limiting the ability to elevate engine-out temperatures for the early exhaust valve opening strategy. Alternatively, late exhaust valve opening realizes up to ~51% increase in exhaust flow and 91 °C increase in engine-out temperature relative to conventional idle operation by forcing the engine to work harder to pump in-cylinder gases across a smaller exhaust valve opening. In short, this study demonstrates how increased idle speeds, and exhaust valve opening modulation, individually or combined, can be used to significantly increase the “warm-up” rate of an aftertreatment system.

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A Multi-Cylinder HCCI Engine Model for Control

Dynamic Systems and Control, Parts A and B ◽

10.1115/imece2004-61966 ◽

2004 ◽

Cited By ~ 19

Author(s):

Jason S. Souder ◽

Parag Mehresh ◽

J. Karl Hedrick ◽

Robert W. Dibble

Keyword(s):

Design Process ◽

Control Design ◽

The Other ◽

Variable Valve Timing ◽

Valve Timing ◽

Coupling Effects ◽

Hcci Engine ◽

Engine Model ◽

Hcci Engines ◽

Variable Valve

Homogeneous charge compression ignition (HCCI) engines are a promising engine technology due to their low emissions and high efficiencies. Controlling the combustion timing is one of the significant challenges to practical HCCI engine implementations. In a spark-ignited engine, the combustion timing is controlled by the spark timing. In a Diesel engine, the timing of the direct fuel injection controls the combustion timing. HCCI engines lack such direct in-cylinder mechanisms. Many actuation methods for affecting the combustion timing have been proposed. These include intake air heating, variable valve timing, variable compression ratios, and exhaust throttling. On a multi-cylinder engine, the combustion timing may have to be adjusted on each cylinder independently. However, the cylinders are coupled through the intake and exhaust manifolds. For some of the proposed actuation methods, affecting the combustion timing on one cylinder influences the combustion timing of the other cylinders. In order to implement one of these actuation methods on a multi-cylinder engine, the engine controller must account for the cylinder-to-cylinder coupling effects. A multi-cylinder HCCI engine model for use in the control design process is presented. The model is comprehensive enough to capture the cylinder-to-cylinder coupling effects, yet simple enough for the rapid simulations required by the control design process. Although the model could be used for controller synthesis, the model is most useful as a starting point for generating a reduced-order model, or as a plant model for evaluating potential controllers. Specifically, the model includes the dynamics for affecting the combustion timing through exhaust throttling. The model is readily applicable to many of the other actuation methods, such as variable valve timing. Experimental results validating the model are also presented.

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Application of Multi-Objective Genetic Algorithm (MOGA) for Design Optimization of Valve Timing at Various Engine Speeds

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.264-265.1719 ◽

2011 ◽

Vol 264-265 ◽

pp. 1719-1724 ◽

Cited By ~ 5

Author(s):

A.K.M. Mohiuddin ◽

Md. Ataur Rahman ◽

Yap Haw Shin

Keyword(s):

Genetic Algorithm ◽

Design Optimization ◽

Robust Design Optimization ◽

Primary Concern ◽

Variable Valve Timing ◽

Valve Timing ◽

Engine Valve ◽

Multi Objective ◽

Multi Objective Genetic Algorithm ◽

Variable Valve

This paper aims to demonstrate the effectiveness of Multi-Objective Genetic Algorithm Optimization and its practical application on the automobile engine valve timing where the variation of performance parameters required for finest tuning to obtain the optimal engine performances. The primary concern is to acquire the clear picture of the implementation of Multi-Objective Genetic Algorithm and the essential of variable valve timing effects on the engine performances in various engine speeds. Majority of the research works in this project were in CAE software environment and method to implement optimization to 1D engine simulation. The paper conducts robust design optimization of CAMPRO 1.6L (S4PH) engine valve timing at various engine speeds using multiobjective genetic algorithm (MOGA) for the future variable valve timing (VVT) system research and development. This paper involves engine modelling in 1D software simulation environment, GT-Power. The GT-Power model is run simultaneously with mode Frontier to perform multiobjective optimization.

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