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.

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.

Factors influencing the burn rate characteristics of a spark ignition engine with variable valve timing

2008 ◽  
Vol 222 (11) ◽  
pp. 2147-2158 ◽  
Author(s):  
F Bonatesta ◽  
P J Shayler
Keyword(s):  
Mass Fraction ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Spark Timing ◽  
Piston Speed ◽  
Flame Development ◽  
Variable Valve ◽  
Valve Overlap

The charge burn characteristics of a four-cylinder port-fuel-injected spark ignition engine fitted with a dual independent variable-valve-timing system have been investigated experimentally. The influence of valve timings on the flame development angle and the rapid burn angle is primarily associated with valve overlap values and internal gas recirculation. Conditions examined cover light to medium loads and engine speeds up to 3500r/min. As engine loads and speeds exceeded about 6bar net indicated mean effective pressure and 3000r/min respectively, combustion duration was virtually independent of the valve timing setting. At lower speeds and work output conditions, valve timing influenced burn angles through changes in dilution mass fraction, charge density, and charge temperature. Of these, changes in dilution mass fraction had the greatest influence. Increasing the dilution by increasing the valve overlap produced an increase in both burn angles. The effects of mean piston speed and spark timing have also been examined, and empirical expressions for the flame development and the rapid burn angles are presented.

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

2009 ◽  
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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