Browse Topic: Cams

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Influence of Miller Cycles on Engine Air Flow03-11-02-00114/18/2018
The influence of the intake valve lift of two Miller cycles on the in-cylinder flow field inside a DISI engine is studied experimentally since changes of the engine flow field directly affect the turbulent mixing and the combustion process. For the analysis of the impact of the valve timing on the general flow field topology and on the large-scale flow structures, high-speed stereo-scopic particle-image velocimetry measurements are conducted in the tumble plane and the cross-tumble plane. The direct comparison to a standard Otto intake valve lift curve reveals evidently different impacts on the flow field for both Miller cam shafts. A Miller cycle that features late intake valve closing shows a flow field comparable to the standard Otto valve timing and a tumble vortex of strong intensity can be identified. Hence, turbulent mixing is as sufficient as for the standard Otto valve timing, although the Miller cycle intake valve timing leads to a pressure reduction of approximately 20%. In contrast, a Miller cycle with early intake valve closing and reduced valve lift leads to an alteration of the in-cylinder flow field. The kinetic energy inside the cylinder as well as the vorticity decay to almost zero towards the end of combustion. In conjunction with an early dissolving tumble vortex of low intensity, turbulent mixing becomes insufficient for clean, efficient combustion.
Braun, Marco, Klaas, Michael, Schröder, Wolfgang
Videogrammetry in Vehicle Crash Reconstruction with a Moving Video Camera2018-01-05324/3/2018
In an accident reconstruction, vehicle speeds and positions are always of interest. When provided with scene photographs or fixed-location video surveillance footage of the crash itself, close-range photogrammetry methods can be useful in locating physical evidence and determining vehicle speeds and locations. Available 3D modeling software can be used to virtually match photographs or fixed-location video surveillance footage. Dash- or vehicle-mounted camera systems are increasingly being used in light vehicles, commercial vehicles and locomotives. Suppose video footage from a dash camera mounted to one of the vehicles involved in the accident is provided for an accident reconstruction but EDR data is unavailable for either of the vehicles involved. The literature to date describes using still photos to locate fixed objects, using video taken from stationary camera locations to determine the speed of moving objects or using video taken from a moving vehicle to locate fixed objects. However, techniques to evaluate the position, speed and acceleration of moving objects seen in video taken from moving locations have not been evaluated. To address the increasing prevalence of dash cams and other in-vehicle video and the value in using such video in vehicle crash reconstruction, this paper describes techniques for determining the position and speed of a moving object from digital video taken from a moving vehicle. Evaluations of the accuracy of those techniques were done when provided three different levels of information about the environment: 1 Aerial Photography (USGS) 2 Survey Data (Total Station) 3 3D Scan Data (of both the environment and vehicles)
Manuel, Emmanuel Jay, Mink, Richard, Kruger, Daniel
Design of a New Intake Manifold of a Single Cylinder Engine with Three Stages2017-36-017211/7/2017
The intake system of an internal combustion engine plays a key role to determine its performance. Gas dynamics varies with many factors, such as whether it is fuel injected or carbureted engine, temperature, runner length and diameter, valve timing, number of cylinders and others factors. A careful design of the intake system provides the engineer a possibility to manipulate the dynamics of the gas, allowing taking advantage of the engine's operation at some moments. The aim of the current paper is investigates the effects of intake runner length and diameter on the performance of a four stroke and single cylinder engine, design a three stages intake manifold for this engine and elaborate a design algorithm to find the best intake runner length and diameter configuration. The characteristics that were taken in consideration to evaluate the engine performance were the brake power, volumetric efficiency and trapped gas. The performance evaluation was made with the assistance of a 1D-simulation software called GT-Power and an optimization software, modeFrontier, where it was used to improve the efficiency to choose the best configuration of the intake runner length and diameter of each engine speed. The study showed that in some moments it is possible to achieve a high volumetric efficiency thanks to the tuning effect, which demonstrate that if adjusting the intake runner length and diameter, making the pressure waves arrives exactly at the time when the inlet valve opens, it allows to reach an extra boosting on the admission time.
Alves, Luiz Otávio F. T., dos Santos, Marcos Gabriel Diodato, Urquiza, Alexandre Barreto, Guerrero, Jorge Henriquez, de Lira, José Claudino, Abramchuk, Vagner
Comparing the Effect of a Swirl Flap and Asymmetric Inlet Valve Opening on a Light Duty Diesel Engine2017-01-242910/8/2017
Diesel engine designers often use swirl flaps to increase air motion in cylinder at low engine speeds, where lower piston velocities reduce natural in-cylinder swirl. Such in-cylinder motion reduces smoke and CO emissions by improved fuel-air mixing. However, swirl flaps, acting like a throttle on a gasoline engine, create an additional pressure drop in the inlet manifold and thereby increase pumping work and fuel consumption. In addition, by increasing the fuel-air mixing in cylinder the combustion duration is shortened and the combustion temperature is increased; this has the effect of increasing NOx emissions. Typically, EGR rates are correspondingly increased to mitigate this effect. Late inlet valve closure, which reduces an engine’s effective compression ratio, has been shown to provide an alternative method of reducing NOx emissions. Recently introduced technologies combine these two effects by retarding only the swirl port valve, increasing in-cylinder swirl while simultaneously reducing the effective compression ratio. In this paper the effects of using a swirl flap and offset cams are compared. Four different swirl flap positions (ranging from fully open to fully closed) were investigated using standard cams and valve timings. Results were compared with the engine’s operation when using two offset cams providing two different levels of retard on the swirl port-30 and 60 crank angle degrees (CAD) respectively. Engine emissions, fuel consumption, and combustion parameters were measured and compared in order to elucidate the effects of phased cam operation. The results show that the use of a cam retarding the opening of the swirl port can reduce NOx emissions at certain speed/load conditions without adversely affecting other emissions. In addition significantly retarding the swirl port closure can reduce FSN emissions to near zero with low NOx emissions, by a combination of high levels of swirl and a reduced effective compression ratio.
Leach, Felix, Davy, Martin, Weall, Adam, Cooper, Brian
A Comparative Study on Influence of EIVC and LIVC on Fuel Economy of A TGDI Engine Part I: Friction Torques of Intake Cams with Different Profiles and Lifts2017-01-224510/8/2017
In order to better understand how the Atkinson cycle and the Miller cycle influence the fuel consumption at different engine speeds and loads, an investigation was conducted to compare influences of early intake valve closing (EIVC) and late intake valve closing (LIVC) on the fuel consumption of a 1.5L turbo-charged gasoline direct injection (TGDI) engine. The engine was tested with three different intake cams, covering three intake durations: 251 degCA (the base engine), 196 degCA (the Miller engine), and 274 degCA (the Atkinson engine). Compression ratios are 9.5:1 for the base engine and 11.4:1 for the Atkinson and Miller engines, achieved with piston modifications. Results of this investigation will be reported in three papers focusing respectively on characteristics of the engine friction, in-cylinder charge motions for different intake events, and combustion and fuel economy without and with EGR for the naturally aspirated mode and boost mode. The present paper is Part I of this investigation. This study reports the results of detailed analyses as well as experiments on characteristics of the cam dynamics and friction forces for the three different intake cams at engine speeds from 700 to 5700 rpm. It was found that, for the three engines investigated in this study, the maximum motoring friction torque for the Atkinson engine was about 3% greater and the Miller engine was about 3% less than that of the base engine. Differences in the engine friction torques decreased with increasing the engine speed, and became insignificant at 5700rpm.
Ouyang, Xianlin, Teng, Ho, zeng, Xiaochun, Luo, Xuwei, Hu, Tingjun, Huang, Xianlong, Luo, Jiankun, Zhou, Yongli
Investigations on Ventilation Strategies for SI Cylinder Deactivation Based on a Variable Valve Train2016-01-234610/17/2016
Advanced SI engines for passenger cars often use the cylinder deactivation technology for dethrottling and thus achieving a reduction of fuel consumption. The gas exchange valves of the deactivated cylinders are closed permanently by a zero lift of the cams. The solutions for cylinder deactivation can vary in the kind of gas composition included in the deactivated cylinders: charge air, exhaust gas or vacuum. All these strategies have in common the frequent loss of captured charge mass from cycle to cycle. Their two-stroke compression-expansion cycle additionally intensifies this phenomenon. Thus, a significant decrease of the minimum cylinder pressure can cause an undesired entry of lubricant into the combustion chamber. The idea was to ventilate the generally deactivated cylinders frequently to compensate the loss of captured cylinder charge mass. The task was to keep the minimum cylinder pressure above a certain limit to prevent the piston rings from a failure. However, a compromise has to be found about the value of IMEP the deactivated cylinders perform in dependence of the included charge mass. The experimental design for this investigation contains a large variety of parameters: type of inclusion, choice of ventilation valves, phase, intensity and frequency of ventilation. Some parametric combinations can be an interesting compromise. They use a ventilation phase at BDC_HP 180°CA before firing TDC in contact to the intake manifold or at BDC_GE 180°CA after firing TDC in contact to the exhaust manifold. Both advantageous strategies use small valve lift curves and low ventilation frequencies.
Gottschalk, Wolfram, Fink, Rene, Schultalbers, Matthias
Influence of Fuel Dilution of Crankcase Oil on Ignitability of Oil Particles in a Highly Boosted Gasoline Direct Injection Engine2015-01-28119/29/2015
The relationship between fuel dilution of the crankcase oil and low-speed pre-ignition (LSPI) was studied experimentally with a highly-boosted 1.8L turbocharged gasoline direct injection (TGDI) engine fueled with RON93 gasoline. It was found that properties of oil particles entered the engine cylinder were affected significantly by fuel dilution. The gasoline content in the oil represents those with long carbon chain or heavy species in gasoline, with much lower boiling points and auto ignition temperatures than those for the undiluted engine oil. Thus, dilution of the engine oil by these gasoline species lowers the volatility and the minimum auto ignition temperature of the engine oil. With 15% fuel content in the oil, the flash point and the fire point of the SAE 5W30 oil dropped from 245 °C to 90 °C and from 265 °C to 150 °C, respectively. The initial boiling point for the diluted oil could be lower than the wall temperatures for some locations on the combustion chamber roof or on the cylinder wall above the top piston ring reverse location. Once attached onto these hot areas, the oil particles entering the engine cylinder could form self-ignitable gaseous mixture easily, and become self ignited in late of the compression stroke under high loads, triggering pre-ignition. It was demonstrated that frequency of LSPI is linked strongly to the minimum auto ignition temperature of the oil particles.
Hu, Tingjun, Teng, Ho, Luo, Xuwei, Lu, Chun, Luo, Jiankun
Synergy between Boost and Valve Timings in a Highly Boosted Direct Injection Gasoline Engine Operating with Miller Cycle2015-01-12624/14/2015
Gasoline engine downsizing has become a popular and effective approach to reduce CO2 emissions from passenger cars. This is typically achieved in the form of a boosted direct injection gasoline engine, which are typically equipped with variable valve timing (VVT) devices on the intake and/or exhaust valves. This paper describes the synergies between valve timings and boost based on experimental investigations in a single cylinder gasoline direct injection spark ignited (DISI) engine with variable cam phasing on both the intake and exhaust cams. Two cam profiles have been tested to realize Miller cycle and compared with the standard camshaft. One cam features a long opening duration and standard valve lift for Late Intake Valve Closing (LIVC) and the other cam has a short opening duration and low valve lift for Early Intake Valve Closing (EIVC). An external boost rig was used to provide adjustable pressurized air charge, allowing conditions of up to 4000rpm and 25.6 bar NIMEP to be studied. Results have shown that the EIVC cam produced the best net Indicated Specific Fuel Consumption (ISFC) among the three cam profiles, with up to 11% improvement in net ISFC relative to the standard cam profile. The benefits of late split injections have also been studied to overcome the issue of low combustion speed when using low valve lift.
Li, Yuanping, Zhao, Hua, Stansfield, Phil, Freeland, Paul
The New Toyota 1.2-Liter ESTEC Turbocharged Direct Injection Gasoline Engine2015-01-12684/14/2015
Toyota Motor Corporation is developing a series of engines belonging to its ESTEC (Economy with Superior Thermal Efficient Combustion) development concept. This paper describes the development of 8NR-FTS after the subsequent launch of the 2.0-liter DI Turbocharged 8AR-FTS. 8NR-FTS is a 1.2-liter inline 4-cylinder spark ignition downsized turbocharged direct injection (DI) gasoline engine. By following the same basic concepts as 8AR-FTS engine [1], the 8NR-FTS incorporates various fuel efficient technologies such as a cylinder head with an integrated exhaust manifold, the Atkinson cycle using the center-spooled variable valve timing with mid-position lock system (VVT-iW), and intensified in-cylinder turbulence to achieve high-speed combustion. Instead of the D-4ST (Direct injection 4-stroke gasoline engine Superior version with Turbo) system that incorporates port and direct injection, this engine adopts the D-4T (Direct injection 4-stroke gasoline engine with Turbo) system that performs only DI in each cylinder. In combination with a single-scroll turbocharger, high torque is achieved from low engine speeds by cooperative control with the VVT system. This engine also adopts a stop and start control strategy that achieves speedy and shock-free re-start performance by starting the engine with stratified injection in the first compressed cylinder. The engine can be mated with either a 6-speed manual transmission (6MT) or continuously variable transmission (CVT). Especially with CVT, turbocharger lag duration is reduced by shifting control, and both fun-to-drive dynamic performance and excellent fuel economy are capable by switching two driving mode; “normal” or “sport”.
Shinagawa, Tomohiro, Kudo, Masahito, Matsubara, Wataru, Kawai, Takashi
An Experimental Investigation on Low Speed Pre-Ignition in a Highly Boosted Gasoline Direct Injection Engine2015-01-07584/14/2015
The biggest challenge in developing Turbocharged Gasoline Direct Injection (TGDI) engines may be the abnormal combustion phenomenon occurring at low speeds and high loads, known as low-speed pre-ignition (LSPI). LSPI can trigger severe engine knocks with intensities much greater than those of spark knocks and thus characterized as super knocks. In this study, behavior and patterns of LSPI were investigated experimentally with a highly-boosted 1.5L TGDI engine. It was found that LSPI could occur as an isolated event, a couple of events in sequence, or a trail of events. Although occurring randomly among the engine cylinders, LSPI took place frequently when the engine was operated at low speeds and high loads in the zone where scavenging was employed for boosting engine torques at low speeds, typically < 2500 rpm. Frequencies and patterns for LSPI were found to be influenced considerably by engine operation parameters, such as excess air coefficient, engine coolant temperature, valve timing, etc. Intensities of super knocks triggered by LSPI varied with the timing for the pre-ignition. Based on findings in this study, it was proposed that the oil particles as oil loading in the blowby recirculation could be the root cause for LSPI as they cause dirtiness of the combustion chamber roof where the oil particles could be attached and then initiate LSPI in the late compression stroke. It was demonstrated that although LSPI may not be eliminated due to the nature of the triggers, TGDI engines can be operated super-knock free through controlling conditions for combustion and engine cooling. As long as the values of the maximum peak firing pressure in LSPI events and their frequencies are under the design criteria, the engine can tolerate the LSPI events with acceptable knock intensities.
Luo, Xuwei, Teng, Ho, Hu, Tingjun, Miao, Ruigang, Cao, Liming
Mitigating Intensities of Super Knocks Encountered in Highly Boosted Gasoline Direct Injection Engines2015-01-00843/30/2015
Turbocharged gasoline direct injection (TGDI) engines can achieve a very high level of brake mean effective pressure and thus the engines can be downsized. The biggest challenge in developing highly-boosted TGDI engines may be how to mitigate the pre-ignition (PI) triggered severe engine knocks at high loads and low engine speeds. Since magnitudes of cylinder pressure fluctuations during aforementioned engine knocks reach those for peak firing pressures in normal combustion, they are characterized as super knocks. It is widely believed that the root cause for super knocks is the oil particles entering the engine cylinder, which pre-ignite the cylinder mixture in late of the compression stroke. It is neither possible nor practical to completely eliminate the oil particles from the engine cylinder; a reasonable approach to mitigate super knocks is to weaken the conditions favoring super knocks. This paper reports the results of an experimental investigation on the conditions that potentially lead to PI and methods to suppress super knocks. Various parameters that could affect engine combustion were studied. It was found that intensities of super knocks varied considerably with the air-fuel ratio for the mixture, the engine cooling temperature, and volatility of the crankcase oil. It was demonstrated that through an appropriate control of the engine operation parameters, the TGDI engine can be operated super-knock free.
Luo, Xuwei, Teng, Ho, Hu, Tingjun, Miao, Ruigang, Cao, Liming
Extended Range Cam Phasing Effects on Engine Stop/Start Quality2014-01-17004/1/2014
Engine stop/start systems are one technology being developed to meet ever tightening fuel economy regulations. Several production vehicles in the market have adopted stop/start systems with 12 volt batteries and enhanced starters. During engine autostart events (restart after autostop), the engine/vehicle vibration may be objectionable to customers. In this paper, the impact of extended range retarded intake cam phasing on first cycle combustion and vehicle vibration during engine autostart is provided. The engine intake cam phasers of a production vehicle were modified so the effective compression during autostart could be set as low as 3.5. Achieving these autostart conditions while maintaining typical cam timing positions under cold start conditions is achievable with an innovative dual park phaser. NVH measurements and engine speed traces indicate that this approach reduced vibration during engine autostart by a measurable amount. Subjective driver feedback was also positive. Cylinder pressure measurements at various intake cam timing settings during autostart indicate that retarded intake cam phaser can reduce the tendency of pre-ignition, reduce peak cylinder pressure, and improve combustion control with retarded spark timing.
Liu, Xiaobing, Nahra, Paul, Strehlau, Anna
Development of Two-stage Turbocharger System for Off Road Application Diesel Engine in Order to Achieve 75 HP2013-01-274911/27/2013
This paper is about downsizing for off road vehicle diesel engines. While fuel efficiency has to be improved, future Diesel engine emission standards will further restrict vehicle emissions, particularly of nitrogen oxides. Increased in-cylinder filling is recognized as a key factor in addressing this issue, which calls for advanced design of air and exhaust gas recirculation circuits and high cooling capabilities. Two stage turbocharging applied to off road diesel engines is a promising solution for enhancing rated power, low end torque, transient performance, better low-speed torque, longer turbo life and optimized fuel efficiency. In the new engine design, two turbochargers are arranged in series to generate increased air pressure, airflow and a superior turbocharging effect. At high altitudes, 2-stage turbocharging technology guarantees the engine's operational performance by compensating for the reduced air density. However, a trade-off is required to match some conflicting issues, i.e. overall dimensions, cost, emissions control and performance. The outcome strongly depends on the specific constraints and goals of the project. In the paper, reference is made to 3.21L, 4 cylinder in-line diesel engine for off road application. The development methodology used to achieve high pressure ratio turbocharging is discussed; along with operating limitations. The study demonstrate that, on the off road vehicle engine, the use of a super charging system made up by a low pressure turbocharger and high pressure turbocharger is able to noticeably enhance engine performance at full load, with further advantages, in comparison to the other analyzed system, in terms of fuel consumption and emission control.
Quazi, Muzaffar Ali, Dhiman, Vikas, singh, shakti
Development of New Gasoline Engine for ACCORD Plug-in Hybrid2013-01-17384/8/2013
The new 2.0L gasoline engine for ACCORD Plug-in Hybrid was developed as a next-generation Honda engine series. This engine's features are low fuel consumption and good emission performance. Variable valve Timing and Electric Control (VTEC) system is applied to this engine, so we can have two characteristic cams, output cam and fuel economy (FE) cam. Output cam is narrow duration, used for power and engine starting. FE cam is wide duration, so it can get Atkinson cycle effect by late intake valve close timing (IVC). Cooled exhaust gas recirculation (Cooled-EGR) is applied to this engine. Low fuel consumption is achieved by combining VTEC and cooled EGR. We made the improvement of control systems. First is the new control which can secure the pressure difference before and behind the EGR valve. As a result, EGR flow control performance is improved. Second is improvement of torque control. It can predict an engine torque decrease when ignition retard is carried out. We keep drivability and fuel consumption in severe condition. Last is the control which changes an operating point according to atmospheric pressure. It can keep low fuel consumption, if environmental change occurs. New quick warm-up system for hybrid vehicle catalyst is developed. At engine starting, engine load was controlled by changing operation of the motor. It became possible to warm catalyst effectively. As a result, tail pipe emissions could be reduced and SULEV20 regulation was suited.
Yonekawa, Akiyuki, Ueno, Masaki, Watanabe, Osamu, Ishikawa, Naohiro
Analysis of Ticking Noise from Cam Bearing of a Diesel Engine2012-01-16259/10/2012
Improving idle sound quality as well as reducing idle noise level is increasingly demanded for diesel engines. Therefore, unusual noise occurrence at idle is a serious problem, and the noise must be removed. This paper describes the characteristics and mechanism of ticking noise that is unusual noise radiated from the journal bearing of the camshaft at low idle speeds, based on the mechanism of cavitation in oil film existing between the journal and bearing.
Kimura, Jouji, Kasai, Ayumi, Saitoh, Shuji, Yamamoto, Atsushi, Takeshige, Naoya
Investigations on a Catalyst Heating Strategy by Variable Valve Train for SI Engines2012-01-11424/16/2012
The objective of this investigation was to evaluate the effects of a variable intake and exhaust valve timing in terms of opening, closing, opening duration, lift curve and number of active valves per pair on a four cylinder direct-injecting SI engine for the catalyst heating idling phase at the beginning of an NEDC emission test procedure. The first step evaluated the engine behavior at a reference point of operation. Its parameters in valve timing were adjusted to match the valve timing of the base production engine. The second step investigated the effects of an earlier exhaust valve opening while the exhaust valve closing time was kept and the exhaust valve opening duration was extended. The third step was to answer the question for the optimum number of exhaust valves in order to minimize the wall heat losses inside the cylinder head. The optimum 3V exhaust valve timing has been defined as the basis for exhaust valve timing for steps four and five. The fourth step contained the variation of intake valve opening and closing. The group of selected optimum valve timing / ignition timing combinations mainly consists of late intake valve opening and decreased intake valve opening durations. The fifth and final step was to evaluate the optimum number of intake valves in order to find out whether it makes sense to add another source of charge motion. It can be stated that a combination of both a late intake valve opening and intake valve deactivation must be excluded for this evaluated catalyst heating point of operation. From this point of view, two alternative VVT strategies with comparable potential can be seen: either late intake valve opening with decreased intake valve opening duration, or intake valve deactivation with standard intake valve opening duration and a slight valve overlap. Both of these intake valve strategies have at least one thing in common: a valve train with the digital ability to change the cams is necessary for their realization. Their general potential can be numbered in a 3-13 % increase of exhaust gas and catalyst temperature, a 5-30 % decrease of gaseous emissions output, and a 80-95% decrease of FSN. It also has the potential of a 5-25 % decrease in related standard deviation of imep.
Gottschalk, Wolfram, Kirstein, Gunnar, Magnor, Olaf, Schultalbers, Matthias, Wetten, Robert
Co-Simulation of Multiple Software Packages for Model Based Control Development and Full Vehicle System Evaluation2012-01-09514/16/2012
Recent advancements in simulation software and computational hardware make it realizable to simulate a full vehicle system comprised of multiple sub-models developed in different modeling languages. The so-called, co-simulation allows one to develop a control strategy and evaluate various aspects of a vehicle system, such as fuel efficiency and vehicle drivability, in a cost-effective manner. In order to study the feasibility of the synchronized parallel processing in co-simulation this paper presents two co-simulation frameworks for a complete vehicle system with multiple heterogeneous subsystem models. In the first approach, subsystem models are co-simulated in a serial configuration, and the same sub-models are co-simulated in a parallel configuration in the second approach. In order to demonstrate their capability, these two co-simulation methods are applied to a full vehicle system with two sub-models developed in different simulation environments: GT-POWER for the engine and MATLAB/Simulink for the driveline and the vehicle dynamics. The simulation results closely match experimental data, although there exist some discrepancies in their relative magnitudes. However, when compared together, the two co-simulation methods produce nearly the same results, while the parallel simulation could reduce the computation time by 25.7%.
Sweafford, Trevor, Yoon, Hwan-Sik, Wang, Yanying, Will, Anthony
Intake Manifold Length Effects on Turbocharged Gasoline Downsizing Engine Performance and Fuel Economy2012-01-07144/16/2012
Downsizing of the spark ignition engine is accepted as a key contributor to reducing fuel consumption. Turbocharged engines are becoming commonplace in passenger vehicles, replacing naturally aspirated larger capacity engines. However, turbocharged engines have typically suffered from “lag” during transient operation. This perceived effect is a combination of the low speed steady state torque and a slower rate to reach maximum torque during a load step. In order to increase customer acceptance of downsized concepts it is vital that the low speed torque and transient response are optimized. Variable Length Intake Manifolds (VLIM) have long been an established method of improving the full load performance of naturally aspirated engines. The manifold length being “tuned” to provide a high-pressure pulse at intake valve closing to maximize cylinder filling and deliver improved performance. This same approach could be applied to turbocharged engines to improve low speed torque and transient response. This paper investigates the affects of VLIM technology applied to a 1.4-litre turbocharged gasoline direct injection engine. It demonstrates improvements in low speed torque and transient response achieved through tuning. It also investigates the tuning options available at high speed on a turbocharged engine and demonstrates the fuel consumption benefits that can be achieved through varying manifold runner length.
Taylor, James, Gurney, David, Freeland, Paul, Dingelstadt, Rene, Stehlig, Jürgen, Bruggesser, Veit
Scuderi Split Cycle Engine: Air Hybrid Vehicle Powertrain Simulation Study2012-01-10134/16/2012
The Scuderi engine is a split cycle design that divides the four strokes of a conventional combustion cycle over two paired cylinders, one intake/compression cylinder and one power/exhaust cylinder, connected by a crossover port. This configuration provides potential benefits to the combustion process, as well as presenting some challenges; it also creates the possibility for pneumatic hybridization of the engine. This paper presents the methodology and results of a comprehensive study to investigate the benefits of air hybrid operation with the Scuderi Split Cycle (SSC) engine. Four air hybrid operating modes are made possible by the Split Cycle configuration, namely air compressor, air expander, air expander & firing and firing & charging. The predicted operating requirements for each individual operating mode are established. The air and fuel flow of the individual modes are fully mapped throughout the engine operating speed and load range and air tank pressure operating range. With the requirements for engine speed and torque derived from a specified drive cycle, the optimum hybrid operating mode at each point is selected to minimize the overall drive cycle fuel consumption. The influence of air storage tank insulation on the vehicle fuel economy is briefly studied. The resulting fuel consumption is compared with that from a non-hybrid SSC powered vehicle to demonstrate the benefits of the pneumatic hybrid architecture.
Meldolesi, Riccardo, Badain, Nicholas
Honda unveils next-gen motorcycle powertrains12AEID0207_022/7/2012
New engines designed for low-speed torque, fuel efficiency, and riding ‘character’ are coupled with new DCT and CVT transmissions. His name is Suzuki, he's head of Honda's motorcycle R&D operation, and he's not shy about praising Harley-Davidson for its torquey, low-rpm, user-friendly engine power delivery. Not only that, he's openly critical of some of his organization's previous product directions. That's pretty unusual stuff for a top Japanese engineer, but the world's largest maker of motorcycles and internal-combustion engines is boldly rethinking its powertrain development path for bikes. And Tetsuo Suzuki, who also is President of the wholly owned Honda Racing Company (HRC), is responsible for the designs and technologies to make it happen.
Yamaguchi, Jack
Design of High Speed Engine's Cam Profile Using B-Spline Functions for Controlled Dynamics2012-28-00061/9/2012
Recent trends towards design of High Performance Diesel engines creating more challenges in the area of design, durability and NVH aspects of components and systems. In particular, Valvetrain system of High Speed application engines is one of the most critical and complicated dynamic system in terms of precise control of events, max. Lift, control over accelerations and vibration related issues. This can be tackled by designing the cam profile for better valve train dynamics. High frequency components and/or excessive jerks in a cam profile are important sources of cam-follower vibrations. There are various techniques of designing cam profile to achieve controlled valve train dynamic behavior at high speed operations. Present paper discuss the impact of various cam profile options designed using Polydyne, N-Harmonic and B-Spline methodologies on a field problem of cam wear for high speed engine application. Conventional Polydyne method for designing the cam profile has certain limitations in controlling the cam accelerations for valve train system operating at high speed. The cam profile designed using N-harmonic algorithm showed better dynamics and improved cam lobe wear. However, this method also has certain limitations in controlling the cam profile curve for the existing pushrod operated valve train system. Cam profile design technique using B-Spline Curves has ability in controlling curve by defining the boundary conditions for higher derivatives. Therefore, B-spline curve algorithm is adopted for cam profile design of High Speed engines in order to control excessive jerks which were the major cause of the vibrations.
Jamkhande, A. K., Tikar, S. S., Ramdasi, S. S., Marathe, N. V.
Modeling of Variable Valve Timing on High Performance Engine using Power-Oriented Graphs Method2011-24-01509/11/2011
Engine efficiency is one of the key aspects to reduce CO2 emissions. In order to improve the emission maintaining high performance capabilities several devices are introduced in the system; variable valve timing technology allows more flexibility for modern engines to meet peak performance, fuel economy and low emissions targets [7] while providing good driveability. This paper describes the Lamborghini continuously-variable cam phaser model using a graphical technique, called Power Oriented Graphs (POG), this uses an energetic approach for representing the physical systems. The generally accepted approach is to calibrate an engine on a dynamometer and to adjust the operation of the engine to meet performance targets. With the current build and test approach, these adjustments may not be made until well into the development program, and this calibration is a costly and time consuming step in the engine development process: the main purpose of this works is showing how was described the model in order to get more easy and fast the calibrating operations. Furthermore the usefulness to model the system consists of analyzing in simulation many more system configurations than those available for real experiments so it's important using a simple methodology that is able to analyze the whole system's dynamic in order to reach the performance expectations. The results obtained were validated demonstrating the effectiveness of the POG technique.
Corvino, Cristian, Calabretta, Michele, Zanasi, Roberto
Sprag Handle WrenchesTBMG-82788/1/2010
Sprag handle wrenches have been proposed for general applications in which conventional pawl-and-ratchet wrenches and sprag and cam “clickless” wrenches are now used. Sprag handle wrenches are so named because they would include components that would function both as parts of handles and as sprags (roller locking/unlocking components). In comparison with all of the aforementioned conventional wrenches, properly designed sprag handle wrenches could operate with much less backlash; in comparison with the conventional clickless wrenches, sprag handle wrenches could be stronger and less expensive (because the sprags would be larger and more easily controllable than are conventional sprags and cams).
Simulation-based Assessment of Various Dual-Stage Boosting Systems in Terms of Performance and Fuel Economy Improvements2009-01-14714/20/2009
Diesel engines have been used in large vehicles, locomotives and ships as more efficient alternatives to the gasoline engines. They have also been used in small passenger vehicle applications, but have not been as popular as in other applications until recently. The two main factors that kept them from becoming the major contender in the small passenger vehicle applications were the low power outputs and the noise levels. A combination of improved mechanical technologies such as multiple injection, higher injection pressure, and advanced electronic control has mostly mitigated the problems associated with the noise level and changed the public notion of the Diesel engine technology in the latest generation of common-rail designs. The power output of the Diesel engines has also been improved substantially through the use of variable geometry turbines combined with the advanced fuel injection technology. However, recent trend in automotive industry suggests that the dual-stage boosting is also essential to further improve the power output of the Diesel engine to the level comparable to that of the other engine technologies. The advantage of the dual-stage boosting system over the single-stage system is the increase in the rated output while simultaneously improving the steady-state torque at low engine speeds and the transient response of the Diesel engine by rapidly building up boost pressure. In this study, several different types of dual-stage boosting systems are evaluated with a physics-based zero-dimensional Diesel engine system simulation in terms of their steady-state and transient performance characteristics and fuel economy improvements. The dual-stage boosting systems evaluated in the study include a boosting system with two fixed geometry turbochargers at both the high pressure and low pressure stages, and several hybrid boosting systems in which the high pressure turbocharger is replaced with a screw type supercharger, an electrical compressor, and a variable geometry turbocharger. A dual-stage boosting system with early intake valve closing (EIVC) strategy is also evaluated. Each alternative system exhibits unique tradeoffs and improvements in terms of performance and fuel economy compared to the dual-stage boosting system with fixed geometry turbochargers at both high and low stages.
Lee, Byungchan, Filipi, Zoran, Assanis, Dennis N., Jung, Dohoy
Development of a Friction Optimized Engine2009-01-10524/20/2009
Evolving emissions legislation and concerns for diminishing fuel reserves continue to prompt the automotive industry to seek improvements in engine operation. The application of advanced combustion and system-based concepts is being studied in detail. However, it is believed prudent to first consider the optimization of the friction of the engine, to allow a more cost effective CO2 and fuel consumption reduction policy. MAHLE has developed an optimised friction engine to demonstrate the potential fuel consumption gains available to engine manufacturers and designers. The baseline 2.0 litre turbocharged, direct injection gasoline engine was modified to suit the application of new friction optimized components. This included piston, ring pack, connecting rod, crankshaft bearings, lubrication system, valvetrain and cooling system. A discussion of the design changes, including analysis results, is made. Motored rig and fired engine test results are presented to show the individual gains. Finally, measured, demonstrator vehicle drive cycle fuel economy results highlight the fuel consumption benefits.
Blaxill, Hugh, Reader, Simon, Mackay, Stewart, Lerch, Boris, Rueckauf, Joerg
Self Organizing Maps (SOM) for Design Selection in Multi-Objective Optimization using modeFRONTIER2008-01-08744/14/2008
Self Organizing Maps (SOM) has evolved as a very useful visualization and data analysis tool for high dimensional data. Visualization and analysis of Pareto data for multi-objective optimization problems with more than three objectives is also a challenge. This paper will investigate the application of SOM for visualization and design selection for multi-objective Pareto data. The SOM is applied to investigate the spread of Pareto front as well as to investigate trade-off between objectives. The visualization and selection strategy is applied to mathematical test problem to explain the concept. Later it is also applied to real world automotive design problem of engine optimization.
Parashar, Sumeet, Fateh, Nader, Pediroda, Valentino, Poloni, Carlo
Electrical Variable Cam Phase Shifter for Internal Combustion Engine2008-01-13514/14/2008
This paper presents a new concept for an electro-mechanical cam phase shifting device (eCPS) along with its control structure. The proposed eCPS features a positive differential gear mechanism with a unique self-locking characteristic. Proof-of-concept simulations were performed using both ADAMS and Simulink analysis tools to evaluate the validity of the concept and its performance. Comparisons with other cam phasers were also discussed. Results confirmed the frictional locking mechanism which not only allows for reduced control effort but also provides the system with an important fail-operational feature. The frictional locking mechanism significantly reduces the reliability burden upon the electric machine. It was indicated that eCPS compares favorably with hydraulic cam phasers in shifting range, position holding, slew rate, system stiffness and power consumption. The performance of eCPS is independent from engine performance characteristics and environmental conditions.
Ai, Xiaolan, Wilmer, Matthew, Remboski, Donald
Getting on the Right Motion BusTBMG-99862/1/2008
As modern machines have become more advanced, the complexity involved in motion control has escalated. Today, servos have replaced cams and gears on machines and multiple axis of synchronized motion control have become commonplace. Distributed motion control requires busses able to handle rigid jitter and timing demands including:
Compact and Long-Stroke Multiple-Link VCR Engine Mechanism2007-01-399110/29/2007
A multiple-link variable compression ratio (VCR) mechanism is suitable for a long-stroke engine by providing the following characteristics: (1) a nearly symmetric piston stroke and (2) an upper link that stays vertical around the time of the maximum combustion pressure. These two characteristics work to reduce force inputs to the piston. The maximum inertial force around top dead center is reduced by the effect of the first characteristic. The second characteristic is effective in reducing piston side thrust force and helps ease piston pin lubrication. Because of the combined effect of these characteristics, the piston skirt can be made smaller and the piston pin can be shortened. That makes it possible for the piston skirt and piston pin to move between the counterweights, resulting in a downward extension of the piston stroke. As a result, a longer-stroke engine mechanism can be achieved without making the cylinder block taller.
Tomita, Masayuki, Aoyama, Shunichi, Ushijima, Kenshi, Tanaka, Yoshiaki, Takahashi, Naoki, Moteki, Katsuya, Tomonori, Takaba
Development of a Variable Valve Timing System for Improving the Performance of a Small Two Wheeler Engine2006-32-010411/13/2006
A novel, fully mechanical, simple, compact and cost effective variable valve timing system for two-wheeler application was developed. The details of the system and the performance are discussed. The system uses flyweights to exert a force on a cam, which floats on a shaft against a spring. The movement of the cam is axial and rotational due helical groves on the shaft. The system could start retarding the cam phasing after a predetermined speed. The system when implemented on a small scooter engine of 125 cc resulted in an increase in the volumetric efficiency at low speeds by 8%. The torque was improved by 10%. There was a reduction in the fuel consumption due to reduced throttling losses and leaner mixtures. When the system was implemented on a two-wheeler and tested on a chassis dynamometer on the Indian Driving Cycle a reduction in fuel consumption of 5% was noted. The emissions were also within limits. On the whole it is concluded that this system can be implemented on small engines for better performance.
Sheth, Nitin R., Ramesh, A.
A Study on the Measurement and Estimation Method of Skew Motion of Roller-Tappets in an OHV Type DI Diesel Engine2006-01-334810/16/2006
Roller-Tappets have been adopted on the valve train systems of OHV type diesel engines, due to their low friction losses. When a roller-tappet is actuated by the cam, it moves upwards and downwards in the guide with a slight skew motion. This motion affects the life of cam and tappets. The purpose of this study was, therefore, to establish the skew estimation method. The skew motion was measured under the engine motoring condition, and its calculation based on the assumed mechanism was carried out. The calculated skew motion showed good agreement with the measured.
Ito, Akemi
Impact of CVCP Position Error on Air Fuel Ratio Control and Adjustment of the Parameters Calibration2006-01-12544/3/2006
A gasoline engine with Continuous Variable Cam Phaser has been considered. An overview of the main functions of the Engine Management System has been given. The catalyst management functions have been accurately described. The impact of CVCP position error on catalyst temperature has been theoretically and experimentally investigated. The experimental results of the analysis have been presented. The necessary corrective actions on the calibration of catalyst management parameters have been explained.
Caraceni, Antonello, Cristofaro, Ferdinando De, Garofalo, Fabio, Sepe, Eduardo
An Experimental Study on HCCI Combustion in a Four-Stroke Gasoline Engine with Reduced Valve Lift Operations2005-01-373610/24/2005
To achieve homogeneous charge compression ignition (HCCI) combustion in the range of low speeds and loads, special camshafts with low intake/exhaust cam lift and short intake/exhaust cam duration were designed. The camshafts were mounted in a Ricardo Hydra four-stroke single cylinder port fuel injection gasoline engine. HCCI combustion was achieved by controlling the amount of trapped residuals from previous cycle through negative valve overlap. The results show that indicated mean effective pressure (IMEP) depends on valve timings, engine speeds and lambda. Early exhaust valve closing (EVC) timings result in high residual fractions in the cylinder and low air mass sucked into the cylinder. As a result, combustion duration increases, IMEP and peak pressure decrease. However, pumping losses decrease. High engine speed has the similar effect on HCCI combustion characteristics as early EVC timings do. But inlet valve opening timings have slight effect on IMEP compared to EVC timings. Irrespective of engine speeds and valve timings, lambda influences gas exchange and combustion processes. Lean mixture decreases the residuals trapped in the cylinder. Furthermore, in the case of lambda 1.05, ignition often occurs early.
He, Bang-Quan, Xie, Hui, Zhang, Yan, Qin, Jing, Zhao, Hua
Experimental And Numerical Analysis Of A Small VVT S.I. Engine2005-24-0799/11/2005
Optimized valve timing, according to engine load, may lead to significant improvements in pumping losses and internal EGR generation. Thus, VVT technology constitutes an effective way to reduce both fuel consumption and pollutant emissions. In this paper, the behavior of a small displacement, 2 valve, Spark-ignition engine, with variable valve timing, has been numerically and experimentally analyzed. The use of VVT allows obtaining combined internal EGR and Reverse Miller Cycle effects so to achieve a significant dethrottling at part load operation. High EGR rates require high turbulence intensity in order to accelerate the combustion rate. The engine performs an accurate combustion chamber design and a tangential intake port able to generate optimized swirl motion, according to the engine speed and load, during both the exhaust gas re-aspiration and the intake stroke. Engine performances at different cam phaser positions have been calculated by means of a 3-D computer code. Many of the obtained results have been compared to the measured data provided by ELASIS research center.
Fontana, G., Galloni, E., Torella, E.
The Effect of Exhaust Variable Cam Phaser Transients on Equivalence Ratio Control in an SI 4 Stroke Engine2005-01-07634/11/2005
It is a well established fact that variable camshaft phasing can be used to reduce engine out emissions during steady state operation. However, a transition in camshaft timing which often accompanies engine speed / load changes, can have a significant dynamic impact on volumetric efficiency. The change in volumetric efficiency can be highly unpredictable, and can last for several engine cycles following the endpoint of cam movement. Since precise control of catalyst feedgas equivalence ratio is crucial to meeting increasingly stringent automotive emission requirements, the steady state benefits of cam phasing can be overshadowed by the loss of A/F control during transient operation if the engine control algorithms are not properly designed and calibrated. This paper investigates the impact of exhaust variable cam phaser transients on equivalence ratio control, and the mechanism by which volumetric efficiency is affected.
Worm, Jeremy
Design and Performance of an Exponential Roller Gear Continuously Variable Transmission with Band Clutches2004-40-00188/23/2004
Many applications will benefit from a higher efficiency continuously variable transmission. This paper presents the design, performance, and measured efficiency of a linear low-slip continuously variable transmission prototype. It discusses the chosen design approach with an emphasis on efficiency and presents improvements on previous designs that make it practical. The ratio variability comes from exponential roller gear and cam gear pairs that function as noncircular gears. The roller/cam pairs are located on three centers of rotation, two fixed and one translating to provide the varying ratio. Two power paths are used and the power from the appropriate path is fed into the output by a band clutch that is synchronized to the output by the exponential gears and tightened by an internal cam. The cam is made up of telescoping segments driven in a nonlinear fashion by the location of the translating axle. Power crosses four gear meshes between the inline input and output shafts. The prototype has a ratio range of 5.85:1. A method of using internal torque to shift the transmission is presented.
Nugent, James
Understanding of Intake Cam Phasing Effects on the Induction and Fuel-Air Mixing in a DISI Engine2004-01-19476/8/2004
Variable Cam Timing (VCT) has been proven to be a very effective method in PFI (Port Fuel Injection) engines for improved fuel economy and combustion stability, and reduced emissions. In DISI (Direct Injection Spark Ignition) engines, VCT is applied in both stratified-charge and homogeneous charge operating modes. In stratified-charge mode, VCT is used to reduce NOx emission and improve combustion stability. In homogeneous charge mode, the function of VCT is similar to that in PFI engines. In DISI engine, however, the VCT also affects the available fuel-air mixing time. This paper focuses on VCT effects on the induction process and the fuel-air mixing homogeneity in a DISI engine. The detailed induction process with large exhaust-intake valve overlap has been investigated with CFD modeling. Seven characteristic sub-processes during the induction have been identified. The associated mechanism for each sub-process is also investigated. Based on the physics of the induction process, the experimentally observed effect of cam phasing on engine manifold pressure is well understood. Both optical engine experiments and CFD modeling showed that retarding the intake cam improves the fuel-air mixing homogeneity over a wide VCT range. Dynamometer engine testing confirms the improved mixing as the CO emission decreases as the intake cam retards. Modeling revealed that the mixing improvement is not due to the overall large-scale in-cylinder flow structure, but due to the local small flow structures.
Yi, Jianwen, Wooldridge, Steve, McGee, Jeff, Han, Zhiyu
Potential of a Mechanical Fully-Variable Valve Lift System for Engines with a Side-Mounted Camshaft2004-01-13953/8/2004
A fully variable mechanical valve gear has been integrated into an engine with a side-mounted camshaft. The design is specified with the peripheral package terms and the resulting criteria of ratings. The additional costs were analyzed too. The first results obtained from a dynamic simulation of the chosen design are described and assessed. Additionally to this the potential of this type of a mechanical fully-variable valve lift system is evaluated in terms of engine torque, power output and fuel consumption by simulating a cyclic process and the comparison with the potential offered by variable valve timing (VVT).
Mohr, Mark A., Flierl, Rudolf, Hannibal, Wilhelm
Analytical Investigation of Cam Strategies for SI Engine Part Load Operation2004-01-09973/8/2004
Extensive simulation was carried out to investigate cam strategies for SI engine part load operation. Performance of the engine with dual independent variable cam timing (VCT) system is assessed. Over a wide range of part load operating conditions, engine performance parameters, such as fuel consumption, were expressed in forms of contour maps as a function of intake and exhaust cam timings. Based upon the simulation results, cam timings were optimized for various part load conditions. A cam strategy incorporating intake and exhaust cam retard was developed to improve fuel economy and emissions. Influences of intake and exhaust cam timing on the gas-exchange and combustion processes were also analyzed. It was shown that the fuel economy improvement by dual independent VCT is achieved primarily through reduction of pumping loss. Effects of in-cylinder charge motion and the use of differential intake cam profiles on fuel economy were examined. The simulation was compared with the experimental data from a single cylinder engine. Good agreement between the prediction and the measurement was observed for most performance parameters interested. Therefore, the simulation provided useful information for understanding of the engine thermodynamic process and guidelines for engine combustion system development.
Fu, Huiyu, Chen, Xiangdong, Mustafa, Erol, Trigui, Nizar, Richardson, Steve, Shilling, Ian
Prediction of Camshaft Torque and Timing Chain Load for Turbo Direct Injection Diesel Engine2004-01-06113/8/2004
The fluctuation of the crankshaft rotational speed of a turbo supercharged direct-injection diesel (hereafter called i-CTDi) engine is large, causing the timing chain load and the valve train driving torque to increase. To overcome this, a simulation method that enables the timing chain load and the valve train driving torque to be predicted while taking account of the fluctuation of the crankshaft rotational speed was established. In this simulation, all of the moving parts centered about the crankshaft were coupled, and an engine in a working condition was faithfully constructed in the computer. In the construction of the model, the issue of the conflicting topics of securing accuracy and reducing computing time was solved by looking at the frequency response of each part and adopting a simple model. As a result, it was possible to predict both the timing chain load and the valve train driving torque with high accuracy and in a short time. Also, this virtual engine was able to contribute to the optimum design of the actual valve train and timing chain.
Takagishi, Hiroshi, Shimoyama, Kazuaki, Asari, Masaru
Application of Secondary Air Injection for Simultaneously Reducing Converter-In Emissions and Improving Catalyst Light-Off Performance2002-01-280310/21/2002
Improving catalyst light-off characteristics during cold start and reducing engine-out (more accurately converter-in) emissions prior to catalyst light-off have been regarded as the keys to meeting future stringent emissions regulations. Many technologies and control strategies have been proposed, and some of them have already been incorporated into production, to address these issues. Among these, secondary air injection received a lot of attention. This study was initiated to investigate the thermal and chemical processes associated with secondary air injection inside the exhaust system in order to maximize the simultaneous benefit of improving catalyst light-off performance and reducing converter-in emissions. The effects of several design and operating parameters such as secondary air injection location, exhaust manifold design, spark timing, engine enrichment level, and secondary air flow rate were carefully examined. It was found that proper design and optimization of secondary air injection can significantly improve catalyst light-off characteristics and reduce converter-in HC emissions.
Borland, Mark, Zhao, Fuquan
Lubrication and Ventilation System of Modern Engines - Measurements, Calculations and Analysis2002-01-13153/4/2002
The main function of an engine's lubrication system is to supply the different engine components with sufficient oil under all operating conditions. The demand of modern engines regarding the necessary oil pressure and flow of the individual components is influenced by the engine speeds and the accelerations due to the vehicle driving conditions. In addition to that, the lubrication system effects the following topics: The drive power of the oil pump which is influenced by the oil pump capacity, the oil pressure and mechanical losses of the oil pump. The oil mass which is supplied to the engine oil consumers and flows back via the oil return system to the crankcase and the oil pan. In the crankcase ventilation system, oil and gas have to be separated. The oil aeration due to the oil mass in the crankcase and the moving parts. The ventilation losses in the crankcase which are influenced by the axial ventilation areas and the moved oil mass. In this paper the development procedure, the measurement techniques used and special devices for the analysis and optimization of the ventilation system will be presented and described.
Koch, Franz, Haubner, Frank G., Orlowsky, Kolja
A Verification Study for Cam Phaser Position Control using Robust Engineering Techniques2001-01-07773/5/2001
This paper describes the verification and comparison of position control algorithms for a continuously-variable cam phaser. Robust Engineering techniques are used. Two non-linear PID control algorithms are designed to control cam phaser position. The first algorithm is a more complex control strategy while the second is a thrifted approach that seeks to reduce throughput requirements. An L18 orthogonal array is established with noise factors that affect the quality of cam phaser control. Using the orthogonal array, the number of experiment test points required to characterize the control algorithm response is reduced from 8,748 to thirty-six. The test points of the orthogonal array are investigated experimentally on a motored engine outfitted with cam phaser hardware. The desired and actual cam position data are compared and analyzed for all points in the orthogonal array. Both control algorithms result in similar signal to noise ratios for the bench testing, showing the thrifted control algorithm to perform similarly overall. A final verification of the control algorithms is performed on a vehicle with a complete engine management system. The more complex control algorithm is shown to yield superior performance in the vehicle-level evaluation.
Pfeiffer, Jeffrey, Kulpa, Matthew J., Simpson, Ken, Reed, Dennis, Yoo, Joon-Ho
Kinematic Solution and Force Layout of a Roller Pump with Internal Outlets2000-01-08333/6/2000
The article presents a theoretical analysis of a roller pump design and a summary of the experiments. The pump is to provide high pressure for transmission, accessory drive, and other applications. A theoretical model was built to simulate the motion of the rollers and optimize the design. An experiment was conducted to prove the simulation. The mathematical model was built within constraints of rigid body mechanics. Comprehensive kinematic and force analysis was done through differential equations of motion. Obtained quantitative relationships include, on one hand, pump geometry, speed of rotation, and discharge/suction oil pressure, and, on the other hand, torque, dynamic interaction of relatively moving parts, and kinematic parameters of the roller. The model includes dissipate forces to account for hydraulic effects. Modeling these forces is beyond mechanics of solid body and is not considered at this initial stage of research. The simulation used matrix algebra, recursive methods of solving non-linear system of equations, ordinary differential equations. Calculations were done by means of MathCad7 Professional software in a MathConnex frame. Tests were conducted on a hydraulic pump test stand with capabilities to set and measure speed, pressure, torque, flow, and temperature. The research showed that a mathematical model built on fundamental scientific basis and strengthened with modern computer tools is valid for explaining available experimental facts; therefore, it may be used for optimizing geometry the model is flexible: new components, such as those representing hydrodynamic effects, may be easily added for better approximation both calculations and experiments revealed some drawbacks of the design; nevertheless, further development is feasible.
Zhurba, Nadezhda, Cleghorn, William
Diagnostics for the Study of Cold Start Mixture Preparation in a Port Fuel-Injected Engine1999-01-11083/1/1999
A variety of diagnostic techniques useful for the study of cold start phenomena are presented. Although the tools are demonstrated in a port fuel-injected engine, they are also suitable for direct-injection gasoline engines. A very useful technique, seemingly forgotten in the literature (and applicable to diesel engines as well), is the use of a short focal-length lens inside a Bowditch piston to expand the field-of-view. Rather than being limited by the clear aperture of the window in the piston, this technique permits the entire combustion chamber and the top section of the cylinder liner to be seen. Results using this technique are presented for the imaging of pool fires and laser-induced fluorescence of fuel films. Two other simple, but overlooked, measurement techniques are described: 1) The cylinder pressure at the time of ignition, or the peak pressure in the absence of ignition, is shown to be a useful measure of the vapor-phase fuel concentration; 2) Thermocouple measurement of the exhaust gas temperature, while too slow-responding to provide an accurate, absolute temperature, does provide a useful relative temperature that is shown to correlate with unburned hydrocarbon emissions. Finally, measurements of flame luminosity at wavelengths characteristic of pool fires were found to increase with increased hydrocarbon emissions only for an ensemble of cold start cycles; on an individual cycle basis, no correlation was found.
Witze, Peter O.
Effect of Valve-Cam Ramps on Valve Train Dynamics1999-01-08013/1/1999
Testing of an OHC valve train with hydraulic lash adjuster in which the valve displacements, velocities and accelerations were measured and analyzed in both time and frequency domains, coupled with analysis of the frequency content of the valve acceleration function and its ramps, show that traditional designs of the opening and closing ramps used on some IC engine valve cams can exacerbate vibration in the follower system causing higher levels of spring surge and noise. Suggestions are made for improvement to the design of the beginning and ending transitions of valve motion which can potentially reduce dynamic oscillation and vibration in the follower train.
Norton, Robert L., Eovaldi, David, Westbrook, James, Stene, Ronald L.
The Importance of Cam Phaser Control to Obtain Emission and Fuel Economy Benefits98295711/9/1998
A Continuously Variable Cam Phaser (CVCP) used in conjunction with the correct control algorithm can help reduce the negative impact on the environment as well as reduce the energy consumed. Cam phasing has the benefit of improving power and emissions while simultaneously improving fuel economy. This paper will discuss the need for having a good control scheme when using a variable cam phaser and the factors that influence its performance. The paper will outline the factors which affect the cam phaser reaction, and hence the control. The paper will also discuss the importance of using feedback control to properly position the CVCP under dynamic conditions.
Kulpa, Mattew J.
Powder Metal Alloys with High Contact Fatigue Properties: Application to Cam Lobes and Bucket Tappet Shims9803312/23/1998
Forged bearing steels and powder forged steels (e.g. AISI 52100, SAE 5160 and MPIF FL-4680) have been used to make cam lobes for assembled camshafts operating with roller followers. Application of powder metal (pressed and sintered) alloys to this and other components that operate under high rolling contact stress has been limited by relatively poor rolling contact fatigue (RCF) properties. This paper introduces developmental sintered steel alloys with high RCF strength. The density of these alloys is 7.4-7.6 Mg/m3 and the macrohardness is 500-800 HV. Endurance limits are in the range 1,700-2,280 MPa. The RCF endurance limit at 200 million stress cycles was determined using a testing rig. Camshafts for a 4.6 L V8 engine and a 4.0 L V6 engine have been assembled. These engines have a single overhead camshaft with end pivot rocker with roller follower (type 2 valve-train). The maximum static normal contact stress on the lobe is approximately 1,200 and 1,500 MPa for the V6 and V8 engines respectively. The camshafts were tested in a motorized cylinder head and in fired engines. After engine testing the sintered cam lobes exhibited no pitting and, in the case of the V8 engine, the cam lobe wear was very similar to the wear observed on powder forged lobes. Initial testing of powder-made tappet shim materials suggests that these alloys may provide a useful alternative for addressing tribological issues that arise between the different combinations of sliding pairs currently used for mechanical bucket tappet designs.
Blanchard, Pierre, Trasorras, Juan R. L., Dempsey, Andrew J., Maulik, Paritosh
LIF and Flame-Emission Imaging of Liquid Fuel Films and Pool Fires in an SI Engine During a Simulated Cold Start9708662/24/1997
Video imaging has been used to investigate the evolution of liquid fuel films on combustion chamber walls during a simulated cold start of a port fuel-injected engine. The experiments were performed in a single-cylinder research engine with a production, four-valve head and a window in the piston crown. Flood-illuminated laser-induced fluorescence was used to observe the fuel films directly, and color video recording of visible emission from pool fires due to burning fuel films was used as an indirect measure of film location. The imaging techniques were applied to a comparative study of open and closed valve injection, for coolant temperatures of 20, 40 and 60 °C. In general, for all cases it is shown that fuel films form in the vicinity of the intake valve seats. For closed valve injection, films also form below the intake valves and below the squish region between the intake valves and the cylinder wall, while for open valve injection additional fuel films form below the exhaust valves. It is expected that fuel films on the head near the exhaust valves are a direct source of unburned hydrocarbon emissions, that fuel films on the cylinder wall are a source of fuel blowby into the crankcase, and that pool fires are a source of soot.
Witze, Peter 0., Green, Robert M.
Development of Titanium Nitride Coated Shim for a Direct Acting OHC Engine9700022/24/1997
In order to meet requirements for lower fuel consumption, we have developed a technique for significantly decreasing valve train friction for a direct acting OHC engine. Droplets of pure titanium generated by the titanium nitride coating process of the shims improves the surface roughness of the cams, which eliminates the need to polish the cams. In an engine with these shims, the surface roughness of the cams is considerably improved within a few minutes of initial operation by the polishing action of the droplets. Valve train friction is greatly reduced by improving the surface roughness of the cams and shims, which results in better fuel economy.
Masuda, Michihiko, Ujino, Masato, Shimoda, Kenji, Nishida, Kouji, Marumoto, Ikuo, Moriyama, Yuhji
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