Development Of A New Fully Flexible Hydraulic Variable Valve Actuation System
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Development Of A New Fully Flexible Hydraulic Variable Valve Actuation System
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Author : Mohammad Pournazeri
language : en
Publisher:
Release Date : 2012
Development Of A New Fully Flexible Hydraulic Variable Valve Actuation System written by Mohammad Pournazeri and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
The automotive industry has been in a marathon of advancement over the past decades. This is partly due to global environmental concerns about increasing amount of air pollutants such as NOx (oxides of nitrogen), CO (carbon monoxide) and particulate matters (PM) and decreasing fossil fuel resources. Recently due to stringent emission regulations such as US EPA (Environmental Protection Agency) and CARB (California Air Resource Board), improvement in fuel economy and reduction in the exhaust gas emissions have become the two major challenges for engine manufacturers. To fulfill the requirements of these regulations, the IC engines including gasoline and diesel engines have experienced significant modifications during the past decades. Incorporating the fully flexible valvetrains in production IC engines is one of the several ways to improve the performance of these engines. The ultimate goal of this PhD thesis is to conduct feasibility study on development of a reliable fully flexible hydraulic valvetrain for automotive engines. Camless valvetrains such as electro-hydraulic, electro-mechanical and electro-pneumatic valve actuators have been developed and extensively studied by several engine component manufacturers and researchers. Unlike conventional camshaft driven systems and cam-based variable valve timing (VVT) techniques, these systems offer valve timings and lift control that are fully independent of crankshaft position and engine speed. These systems are key technical enablers for HCCI, 2/4 stroke-switching gasoline and air hybrid technologies, each of which is a high fuel efficiency technology. Although the flexibility of the camless valvetrains is limitless, they are generally more complex and expensive than cam-based systems and require more study on areas of reliability, fail safety, durability, repeatability and robustness. On the contrary, the cam-based variable valve timing systems are more reliable, durable, repeatable and robust but much less flexible and much more complex in design. In this research work, a new hydraulic variable valve actuation system (VVA) is proposed, designed, prototyped and tested. The proposed system consists of a two rotary spool valves each of which actuated either by a combination of engine crankshaft and a phase shifter or by a variable speed servo-motor. The proposed actuation system offers the same level of flexibility as camless valvetrains while its reliability, repeatability and robustness are comparable with cam driven systems. In this system, the engine valve opening and closing events can be advanced or retarded without any constraint as well as the final valve lift. Transition from regenerative braking or air motor mode to conventional mode in air hybrid engines can be easily realized using the proposed valvetrain. The proposed VVA system, as a stand-alone unit, is modeled, designed, prototyped and successfully tested. The mathematical model of the system is verified by the experimental data and used as a numerical test bench for evaluating the performance of the designed control systems. The system test setup is equipped with valve timing and lift controllers and it is tested to measure repeatability, flexibility and control precision of the valve actuation system. For fast and accurate engine valve lift control, a simplified dynamic model of the system (average model) is derived based on the energy and mass conservation principles. A discrete time sliding mode controller is designed based on the system average model and it is implemented and tested on the experimental setup. To improve the energy efficiency and robustness of the proposed valve actuator, the system design parameters are subjected to an optimization using the genetic algorithm method. Finally, an energy recovery system is proposed, designed and tested to reduce the hydraulic valvetrain power consumption. The presented study is only a small portion of the growing research in this area, and it is hoped that the results obtained here will lead to the realization of a more reliable, repeatable, and flexible engine valve system.
Hydraulic Variable Valve Actuation System
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Author : Mitchell Terpstra
language : en
Publisher:
Release Date : 2019
Hydraulic Variable Valve Actuation System written by Mitchell Terpstra and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Automobiles categories.
Conventional engines with camshafts with fixed timings force a compromise between performance at high engine loads and fuel economy at low engine loads. Adjusting internal combustion engine valve timing and lift through a variable valve actuation (VVA) system is an established method of improving engine performance [1]. A fully flexible hydraulic variable valve actuation (HVVA) system in development at the University of Waterloo allows the valve timing to be optimized for any engine operating condition. This project is a further development of this HVVA system. First, the previous prototype was thoroughly tested and evaluated. Major design issues and challenges were addressed, and changes were incorporated into a new prototype design. This prototype was designed to be robust and more compact than the previous system. A completely new concept was developed for the phasing system used to adjust the valve timings. The new HVVA design was manufactured, assembled, and installed on a single cylinder test engine. Initial experiments of the new HVVA system validated its ability to change engine valve timing and match the profiles of different VVA strategies. The system was able to switch between different profiles in
Variable Valve Actuation
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Author :
language : en
Publisher:
Release Date : 2008
Variable Valve Actuation written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release rate and combustion phasing. Figure 1 shows that a systems approach is required for HCCI-like combustion. While the exact requirements remain unclear (and will vary depending on fuel, engine size and application), some form of substantially variable valve actuation is a likely element in such a system. Variable valve actuation, for both intake and exhaust valve events, is a potent tool for controlling the parameters that are critical to HCCI-like combustion and expanding its operational range. Additionally, VVA can be used to optimize the combustion process as well as exhaust temperatures and impact the after treatment system requirements and its associated cost. Delphi Corporation has major manufacturing and product development and applied R & D expertise in the valve train area. Historical R & D experience includes the development of fully variable electro-hydraulic valve train on research engines as well as several generations of mechanical VVA for gasoline systems. This experience has enabled us to evaluate various implementations and determine the strengths and weaknesses of each. While a fully variable electro-hydraulic valve train system might be the 'ideal' solution technically for maximum flexibility in the timing and control of the valve events, its complexity, associated costs, and high power consumption make its implementation on low cost high volume applications unlikely. Conversely, a simple mechanical system might be a low cost solution but not deliver the flexibility required for HCCI operation. After modeling more than 200 variations of the mechanism it was determined that the single cam design did not have enough flexibility to satisfy three critical OEM requirements simultaneously, (maximum valve lift variation, intake valve opening timing and valve closing duration), and a new approach would be necessary. After numerous internal design reviews including several with the OEM a dual cam design was developed that had the flexibility to meet all motion requirements. The second cam added complexity to the mechanism however the cost was offset by the deletion of the electric motor required in the previous design. New patent applications including detailed drawings and potential valve motion profiles were generated and alternate two cam designs were proposed and evaluated for function, cost, reliability and durability. Hardware was designed and built and testing of sample hardware was successfully completed on an engine test stand. The mechanism developed during the course of this investigation can be applied by Original Equipment Manufacturers, (OEM), to their advanced diesel engines with the ultimate goal of reducing emissions and improving fuel economy. The objectives are: (1) Develop an optimal, cost effective, variable valve actuation (VVA) system for advanced low temperature diesel combustion processes. (2) Design and model alternative mechanical approaches and down-select for optimum design. (3) Build and demonstrate a mechanism capable of application on running engines.
Design And Development Of A Regenerative Hydraulic Variable Timing Engine Valve Actuator
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Author : William E. Tourdot
language : en
Publisher:
Release Date : 2002
Design And Development Of A Regenerative Hydraulic Variable Timing Engine Valve Actuator written by William E. Tourdot and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
Development Of A Hydraulic Variable Valve Actuator
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Author : Geoffrey Leyland
language : en
Publisher:
Release Date : 1996
Development Of A Hydraulic Variable Valve Actuator written by Geoffrey Leyland and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Actuators categories.
Design And Control Of Automotive Propulsion Systems
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Author : Zongxuan Sun
language : en
Publisher: CRC Press
Release Date : 2014-12-20
Design And Control Of Automotive Propulsion Systems written by Zongxuan Sun and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-12-20 with Science categories.
Better Understand the Relationship between Powertrain System Design and Its Control IntegrationWhile powertrain system design and its control integration are traditionally divided into two different functional groups, a growing trend introduces the integration of more electronics (sensors, actuators, and controls) into the powertrain system.
Recent Advances In Materials And Modern Manufacturing
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Author : I. A. Palani
language : en
Publisher: Springer Nature
Release Date : 2022-05-26
Recent Advances In Materials And Modern Manufacturing written by I. A. Palani and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-05-26 with Technology & Engineering categories.
This book presents the select proceedings of the fourth International Conference on Advanced Materials and Modern Manufacturing (ICAMMM 2021). It covers broad areas such as advanced mechanical engineering, material science and manufacturing process. Various topics discussed in this book include green manufacturing, green materials, Industry 4.0, additive manufacturing, precision engineering, sustainability, manufacturing operations management and so on. Given its contents, the book will be useful for students, researchers, engineers and professionals working in the area of mechanical engineering and its allied fields.
Advances In Automotive Control 2004 2 Volume Set
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Author : G Rizzo
language : en
Publisher: Elsevier
Release Date : 2005-11-07
Advances In Automotive Control 2004 2 Volume Set written by G Rizzo and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005-11-07 with Science categories.
Hydraulic Variable Valve Timing Testing And Validation
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Author : Matthew Chermesnok
language : en
Publisher:
Release Date : 2016
Hydraulic Variable Valve Timing Testing And Validation written by Matthew Chermesnok and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
This thesis documents the development of a fully continuous, hydraulics-based variable valve timing system. This hydraulics based variable valve timing system is capable of controlling an engine valves lift height and infinitely varying the engine valves lift profile. Along with full valve controllability during normal operation, the variable valve timing system is capable of providing the same operation as a classic cam shaft under engine power loss conditions. This is possible due to the rotating hydraulic spool valves coupled to the engines crank shaft, which are used to actuate the engine poppet valves. The main focus of this thesis is to investigate, alter and implement a new iteration of the hydraulic variable valve timing system on a standalone test bench to validate the systems operating principles. The test bench utilizes servo motors to act as an engines crank shaft which runs the rotating hydraulic spool valves and hydraulic pump. This serves as an intermediate step to full engine implementation of the variable valve timing system. The research begins by analyzing the current mechanical spool valve and hydraulic cylinder design for any potential problems that may occur either during assembly or full operation. The basic system equations are presented to give a glimpse into the working principles of the rotary valves. The mechanical, electrical, and hydraulic subsystems are discussed in terms of what was considered during the design and implementation process. Then design changes that were performed on the rotary valve system to overcome any failures. Lastly the resulting data is presented from the current variable valve timing design to verify proper system functionality.
Hcci Load Expansion Opportunities Using A Fully Variable Hva Research Engine To Guide Development Of A Production Intent Cam Based Vva Engine
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Author :
language : en
Publisher:
Release Date : 2012
Hcci Load Expansion Opportunities Using A Fully Variable Hva Research Engine To Guide Development Of A Production Intent Cam Based Vva Engine written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
While the potential emissions and efficiency benefits of HCCI combustion are well known, realizing the potentials on a production intent engine presents numerous challenges. In this study we focus on identifying challenges and opportunities associated with a production intent cam-based variable valve actuation (VVA) system on a multi-cylinder engine in comparison to a fully flexible, naturally aspirated, hydraulic valve actuation (HVA) system on a single-cylinder engine, with both platforms sharing the same GDI fueling system and engine geometry. The multi-cylinder production intent VVA system uses a 2-step cam technology with wide authority cam phasing, allowing adjustments to be made to the negative valve overlap (NVO) duration but not the valve opening durations. On the single cylinder HVA engine, the valve opening duration and lift are variable in addition to the NVO duration. The content of this paper is limited to the low-medium operating load region at 2000rpm. Using different injection strategies, including the NVO pilot injection approach, the single-cylinder engine is operated over a load range from 160-390 kPa net IMEP at 2000 rpm. Changes to valve opening duration on the single-cylinder HVA engine illustrate opportunities for load expansion and efficiency improvement at certain conditions. For instance, the low load limit can be extended on the HVA engine by reducing breathing and operating closer to a stoichiometric air fuel ratio (AFR) by using valve deactivation. The naturally aspirated engine used here without external EGR confirmed that as operating load increases the emissions of NOx increases due to combustion temperature. NOx emissions are found to be one limitation to the maximum load limitation, the other being high pressure rise rate. It is found that the configuration of the production intent cam-based system represents a good compromise between valve lift and duration in the low to medium load region. Changing the extent of charge motion and breathing via valve deactivation prove beneficial at moderating the pressure rise rate and combustion stability and extending the low load limit at 2000rpm on the HVA engine. It also confirms that strategies using a pilot fuel injection are beneficial at low operating loads but that as operating load is increased, the benefits of multiple injection diminish to the point where a single injection offers the best performance.