Browse Topic: Timing chains
To improve the fuel efficiency and satisfy the strict emission regulations, the development of internal combustion engine gets more complicated in both hardware and software perspectives, and the margins for durability and NVH quality become narrower, which could result in poor NVH robustness in harsh engine operating conditions. In this paper, we investigate experimentally the camshaft impact noise mechanism relating the valve train and timing chain forces to detailed motion of the camshaft and the chain tensioner. After the initial investigation of identifying the impact timings and specific engine operating points when the noise occurs, the camshaft orbital motion inside of the sliding bearing is measured and visualized with the proximity sensors with calibration after sensor mounting, in addition to the chain tensioner movements. It is shown that the impact noise occurs at the event of the abrupt change of camshaft orbital motion, which results from the combined resultant force of valve train and timing chain forces. As the valve timing has significant effects on the breathing and combustion efficiency sequentially, only the timing chain force on the camshaft is modified in a way to reduce the abrupt change of movement of the camshaft. In conclusion, the mechanism of camshaft impact has been identified with the proper visualization of the camshaft movement together with the tensioner force-displacement diagram in problematic engine operation condition.
Roots blower is a rotary positive displacement pump which operates by pumping a fluid with a pair of meshing lobes. Recent trends in automotive industry demands high power density solutions for various applications. In comparison with legacy applications, compressors for high power density applications demand continuous operation with harsher duty cycle as well as demand higher pressure ratios. Because of longer duty cycles, it will be subjected to high heat loads which will cause a rise in temperatures of timing gears, bearings, and other components within the assembly. Accurate prediction of thermal performance is critical to design a durable and efficient roots blower for high power density applications. Thermal analysis of an assembly of roots blower involves modelling of multi-physics phenomena. This paper details a coupled CFD analysis approach to predict temperatures of roots blower components and timing gear case oil. Timing gears are lubricated using wet sump lubrication. The oil splash within the timing gear enclosure is modelled using moving reference frame model in a multiphase splash analysis. Air flow through rotors is modelled using deforming zone method in a transient CFD analysis. An approach is presented to perform steady state conjugate heat transfer to couple physics from oil splash and air flowing through rotating lobes to predict thermal performance of roots blower assembly. The results using this approach are validated against a test case. The temperature results from 3D CFD analysis shows a variation within 10% compared to the temperature values measured using thermocouple sensors in test setup. The approach presented in this paper helps to predict the thermal profile of solid components. This will further be utilized in designing the critical clearances and understanding bearing-housing bore distortions for improving performance and durability of roots blower.
The major area in which the automotive manufacturers are working is to produce high-performance vehicles with lighter weight, higher fuel economy and lower emissions. In this regard, hollow camshafts are widely used in modern diesel and gasoline engines due to their inherent advantages of less rotational inertia, less friction, less weight and better design flexibility. However, the dynamic loads of chain system, valve train and fuel injection pump (if applicable) makes it challenging to design over-head hollow camshafts with the required factor of safety (FOS). In the present work, high-fidelity FE model of a hollow camshaft assembly is simulated to evaluate the structural performance for assembly loads, valve train operating loads, fuel injection pump loads and chain system loads. The investigation is carried out in a high power-density (70 kW/lit) 4-cylinder in-line diesel engine. The camshaft is used for operating the intake valves which induce varying stresses in-line with the engine firing order. Moreover, the camshaft is also used to drive the high-pressure fuel injection pump (FIP) at the rear-end which can add significant torsional stresses. Furthermore, the stresses induced by the hub-loads of timing chain is found to be having a significant effect on the bending behavior of the front-end of the camshaft. In addition to these operating stresses, the camshaft is subjected to different kinds of mean stresses induced by the bolt (used to fasten the drive-sprocket) and interference fit of the camshaft child parts (cam and front plug). Hence, the authors propose a robust and reliable evaluation methodology to evaluate the structural performance and factor of safety (FOS). The dynamic bending behavior of the camshaft under press-fit loads of cam lobes and front plug is discussed. The present work also covers the load-path and multi axial stress state induced on the hollow camshaft under varying load conditions apart from estimating the fatigue life. Moreover, the investigation includes the assessment of different parameters influencing the stress multi-axiality on the camshaft to arrive at potential improvements in the camshaft design. Overall, the results arrived using this methodology is found to be having a good correlation with the parts used for durability testing. Thus, the proposed methodology can be used for evaluating hollow camshafts of modern engines subjected to complex and highly dynamic loads.
Rubbers are widely used in many engineering applications such as tubes, timing belt, tires etc. Apart from its functional use, it can also be used as damping material in many applications in order to dampen the vibrations transmitted from one structure to another. The present research work focuses on the development of Graphene filled (CB) Styrene-Butadiene Rubber (SBR) and its performances are compared with Carbon Black (CB) filled SBR. Both of these rubber samples were investigated for its mechanical properties such as hardness and tensile strength. Experimental modal analysis (EMA) was also carried out to examine the dynamic characteristics such as damping and natural frequency along with its mode shapes for the prepared samples and compared. It is observed from the results that the inclusion of graphene in SBR improved its vibrational characteristics in addition to the improvement of mechanical properties.
In this contribution, the mechanical torque transmission between the Electric Motor (EM) and the Internal Combustion Engine (ICE) of a P0 architecture hybrid power unit is analysed. In particular, the system is made up of a brand new, single-cylinder 480cc engine developed on the basis of the Ducati 959 Panigale V90 2-cylinders engine. The thermal engine is assisted by a custom electric motor (30 kW), powered by a Li-Ion battery pack. The Ducati 959 Panigale engine is chosen because of its high power-to-weight ratio, and for taking advantage of its V90 2-cylinders layout. In fact, the proposed hybridization process considers to remove the vertical engine head and to replace it by the electric motor directly engaged to the crankshaft using the original valvetrain transmission chain, thus achieving a very compact package. This solution could be suitable for many V-type engines and it aims to obtain a small hybrid power unit for possible motorcycle/small vehicle applications. The original timing chain object of this study is a silent chain, which is commonly employed as a transmission component in hybrid power units because it can operate at high speeds transmitting high loads and ensuring noise reduction. For this reason, the aim of this study is to assess the possibility of using the original chain to couple the EM and the ICE. This investigation allows the replacing of the minimum number of components during the hybridization process leading to a real plug&go solution. Therefore, the mechanical behaviour of the chain is investigated performing a dynamic analysis of the whole crank mechanism. In particular, the original twin cylinders model considering the original valvetrain system is compared with the single cylinder model engaged with the EM. The dynamic analysis provides the maximum load on the single chain link in both configurations, allowing the evaluation of a relative fatigue safety factor.
Through improving the 48V hybrid vehicle archetype, governmental emission targets could be more easily met without incurring the high costs associated with increasing levels of electrification. The braking energy recovery function of hybrid vehicles is recognised as an effective solution to reduce emissions and fuel consumption in the short to medium term. The aim of this study was to evaluate methods to maximise the braking energy recovery capability of the 48V hybrid electric vehicle over pre-selected drive cycles using appropriately sized electrified components. The strategy adopted was based upon optimising the battery chemistry type via specific power capability, so that overall brake power is equal to the maximum battery charging power in a typical medium-sized passenger car under typical driving. This will maximise the regenerative braking energy whilst providing a larger torque assistance for a lower battery capacity. Dynamic simulation models were developed using GT-DRIVE software, emulating a mid-sized car with a 48V battery, and different turbocharged gasoline engines with motor-generator unit positions along a drivetrain. The 1.3 kWh battery pack was developed using a 14 Ah Lithium Iron Phosphate cell arranged in a 14 series 2 parallel configuration. A fuel economy comparison was produced using the FTP, WLTP, and HEFET drive cycles. When the motor-generator unit was attached via a synchronous belt, a 10-17% fuel saving was achieved in the WLTP drive cycle. Comparatively, when placing the electric machine after the clutch in a “P2” position, a 17-21% fuel saving was attained. The energy loss analysis of both P2 and P0 configurations revealed up to 7% overall reduction in total energy losses for the P2 setup. This was despite an increase in the motor-generator unit and battery losses due to the extended use of both in the electric-only mode capability with the P2 layout.
This SAE Recommended Practice applies to the function of building reciprocating spark-ignition engines which are used in conjunction with standard and high-performance ancillary components in applications intended to achieve a minimum of 1 hp/in3. This document does not apply to rebuilt engines which may only be partially repaired with little or no machining, nor does it apply to second-hand or used engines.
Direct drive servo motor and drive technology has many advantages. It reduces an axis’ parts count, mechanical losses, and often its objectionable noise. What’s more, it also increases the machine’s efficiency, lowering operation cost for the user due to its inertia ratio as compared to the more common mechanically advantaged multi-body axis designs. Reducing the mechanical transmission components (gearboxes, timing belts, pulleys, cams, lead screws, etc.) between the motor and its load is only part of the savings.
There has been a global technology convergence by engine manufacturers as they strive to meet or exceed the ever-increasing fuel economy mandates that are intended to mitigate the trend in global warming associated with CO2 emissions. While turbocharging and direct-injection gasoline technologies are not new, when combined they create the opportunity for substantial increase in power output at lower engine speeds. Higher output at lower engine speeds is inherently more efficient, and this leads engine designers in the direction of overall smaller engines. Lubricants optimized for older engines may not have the expected level of durability with more operating time being spent at higher specific output levels. Additionally, a phenomenon that is called low-speed pre-ignition has become more prevalent with these engines. While more pre-ignition may be expected with highly-boosted engines, an especially destructive version of this has been found to be related to some of the essential compounds that comprise the lubricant additive package. Newly introduced OEM specifications have been designed to anticipate the needs of these downsized, down-speeded, turbocharged direct injection engines. New areas of protection include: low speed pre-ignition, enhanced protection against turbocharger deposits, and timing chain wear. Since lubricants must still protect and enable many other items associated with durability like sludge, piston deposits, wear, and resistance to oxidation, we discuss a holistic formulation strategy that ensures a maximum level of engine protection and oil durability to enable the highest degree of fuel economy.
When designing a new internal combustion engine, the choice of technology for the timing drive system is one of the key decisions that determines the overall characteristics of the engine with far reaching implications on the remaining architecture and overall packaging of the engine. For Passenger car engines there are two mainstream technologies: toothed belts and chains. Each of these offers several sub-variants, such as dry vs. wet belt, or toothed vs. roller chain. This paper examines the differences between these technologies in relation to the key engine attributes including package, cost, weight, durability, NVH and frictional losses. A quantitative evaluation is made where possible, based on data collected from recent engine development programs, backed up by literature study and data from the component supply industry. These differences are reviewed in the light of current and expected future engine development trends in order to give a basis for the engine designer to choose the appropriate technology for coming years.
Suppliers and engine designers are attacking every potential source of internal friction-no longer a “low-hanging fruit”-as the battle to squeeze more mechanical work from less fuel intensifies. Reducing internal friction has always been a priority of powertrain designers, but recently the subject has taken on greater urgency in the crunch to meet tough new global CO2 regulations. In piston engines, friction loss rises with the square of rpm, which is one reason OEMs are “downspeeding” their new engine families. And with their key suppliers, they're digging deeper to find cost-effective solutions to this century-old challenge-from “rollerizing” camshafts to optimizing lubrication schemes, to new gas-cushion shaft seals, to decoupling front-end drive systems. New materials and surface coatings are also enablers. “We looked across the entire propulsion system to find places we could reduce spin and drag losses and minimize internal friction,” said Tim Grewe, GM's General Director of Vehicle Electrification, speaking to Automotive Engineering about the 2016 Chevrolet Volt. “This is a major area of focus in vehicle development at GM and the industry going forward.”
In the pursuit of design and development of efficient, reliable and durable system and components for modern engines, there is a need to understand complications involved in building mathematical models for simulation. Valve train and timing drive systems are having higher rankings for addressing these attributes. Hence, a new comprehensive multi body dynamics model is built and equations are solved by state-variable approach. Model developed is validated and in order to probe into details of Hydraulic Lash Adjuster (HLA) behavior and coupled analysis of timing chain drive systems for valve train system, simulation is carried out to freeze design options. Engine timing drives used in engines are one of the most critical systems. Timing chains are preferred widely in modern high speed engines as compared to timing belts and gear drives. In spite of advantages of chain drive systems, their complex dynamic behavior is not well researched. The major objective of the current work is to design & develop timing chain drive and valve train system for a high speed three cylinder diesel engine and investigate about its durability. In this research work, dynamic model of type-2 valve train with HLA and chain drive with hydraulically operated tensioners is built in GT valve train software. The final goal is to optimize the valve train and timing system performance by simulation. The results related to timing chain analysis are expressed in terms of parameters such as contact forces, normal forces between different components and link tension etc. The effectiveness of this model calibration technique was confirmed through comparison of unit dynamic characteristics in an excitation test and a calibrated simulation. The proposed simulation process is validated experimentally and has shown considerable reduction in development time with improved robustness.
More and more, the automotive vehicle consumers tend to opt for internal combustion engines which use chain in their timing system, since the chain drive system presents high durability, avoiding the usual maintenance common to the belt timing system. The necessity of developing parts which increase the fuel consumption efficiency and minimize noise and vibration leads to the study and comprehension of some physical phenomena such as “polygonal action” and the ability of predicting the fluctuation of angular velocity of the sprockets used for timing the crankshaft and camshaft. The study of mathematic models in parallel to the physical test guides the development of the present work.
Powertrain engineers are diving deeper to find new ways to make light-duty power units more efficient without compromising performance. As MY2015 approaches, the debut of Atkinson-cycle engines for non-hybrids, diesel-like compression ratios on gasoline engines with sophisticated cooled EGR, low-friction roller-bearing camshafts, and electrically enhanced boosting systems shows the industry is diving deeper into its technology toolboxes to tackle stiff new regulatory challenges. Meanwhile, there's still room for a hairy 707-hp (527-kW) overhead-valve V8 to power Chrysler muscle cars. In Europe, the trend in light-vehicle engines is turning away from the diesel panacea that has driven the market since the 1990s. Euro 6 emission standards are finally approaching the North American benchmark, making compression-ignition engines and their elaborate aftertreatment increasingly costly. DI spark-ignition engines are running dizzy-high compression ratios well above 12:1, downsized turbo engines are earning rave reviews, and the gasoline-vs-diesel efficiency gap is diminishing-the latest analyses pegging it at about 10% for A- and B-class cars. And compared with parallel-type full hybrid systems, the latest gas engines and transmissions are a value.
Light weighting is a critical objective in the automotive industry to improve fuel efficiency. But when redesigning parts for light weight, by changing from metal to plastic, the resulting design gives NVH issues due to differences in part mass and material stiffness. Many parts were not converted from metal to plastic because of NVH issues that could not be solved. Many engine parts such as cylinder head cover, air intake manifold, oil pan and etc. previously made of metal have since long been replaced with plastic. But timing chain cover has not been replaced because of the aforementioned issue. Sealing performance due to the dynamic characteristics of the application is another challenging factor. In this paper, the key aspects of the plastic timing chain cover as well as its advantage are presented.
A proper way to innovate consists in identify some kind of customer dissatisfaction and within this observation the companies ought to develop products which will be acceptable by the market. Only in this way, companies will be able to stand out in front of their competitors and the innovative companies can create new needs and valuable knowledge. More and more, the automotive vehicle consumers tend to opt internal combustion engines which use chain drive in their timing system, since the chain drive system presents high durability, avoiding the usual maintenance common to the belt timing system. The necessity of developing parts which increase the efficiency and minimize the fuel consumption, noise and vibration in the timing chain drive system lead the study and comprehension of some physical phenomena. It is inherent to the chain drive system the fluctuation of the angular velocity between shafts, this feature is known as “polygonal action”. In the present work the fluctuation of the angular rotations between camshafts and crankshafts are treated by the geometry of the transmission. Initially, the chain drive is modeled as being a four bar linkage, following by a more complex way, which uses theory of instant center of zero velocity and acceleration to understand the role of each chain link and the chain guide profile. The chain guides have presented fundamental importance to increase the efficiency of the chain transmissions, consequently, a better understanding about its profile and others phenomena such wear and manufacture process allowed the developing an innovative chain guide which is adaptable and can find market demand.
The all-new premium sedan is the Korean automaker's ‘most technologically advanced’ vehicle ever on U.S. roadways. Kia's first full-size sedan represents the company's most powerful and technologically advanced product offering ever for the North American market. Several months after the Cadenza's January debut at the 2013 North American International Auto Show in Detroit, automotive and lifestyle media including AEI had the opportunity to test-drive the car and experience its 293-hp (218-kW) gasoline direct injection (GDI) V6, its sport-tuned suspension, and suite of active safety technologies including Kia's first application of advanced smart cruise control (ASCC) on the roads surrounding Del Mar, CA. The Cadenza succeeds in moving the Kia brand up-market, from its European-influenced design driven by Kia Motors' President and Chief Design Officer Peter Schreyer (who previously worked at Audi), to its long list of premium features such as an advanced navigation system with SiriusXM Traffic and UVO eServices telematics displayed on a high-resolution 8-in touch screen. (To read more on Kia's UVO infotainment system, go to http://articles.sae.org/11824.)
With fuel costs continuing to rise, and with regulations seeking to lower overall fuel emissions, improved fuel economy has become indispensible for today's gasoline engine designer. Reducing engine friction is an effective means of improving fuel economy and specific engine components have been developed towards this objective. Chain drive system components are no exception to this trend. In an attempt to decrease friction loss in the timing chain system and thereby improving fuel economy, the following three topics were studied: 1) defining sources of friction loss; 2) investigating the effect(s) of each loss factor using friction simulation; and, 3) evaluating methods to minimize friction losses. Chain system friction loss can occur when the chain slides on the Arm & Guide face. Friction loss can also occur between the chain link and pin joint, and during chain engagement with the sprocket. The low friction chain drive system under development is designed for future 2.4L 4-cylinder gasoline engine production.
The overhead camshaft engine efficiency can be improved by control of the rotation and phase of the cam shaft rotation. The aim of this paper is to show the improvements that have been made to the cam shaft rotation through the improvements in the timing belt, and in particular the reinforcing cords within the timing belt. The current state of the art of timing belt reinforcement is presented, and an independent study of the fuel efficiency of a modern timing belt compared to the efficiency of a fully optimised gasoline engine with a timing chain. This considers the power losses due to friction as the timing belt (or chain) transmits power from crank to cam, the power losses expressed as vibrations and noise, the variations in speed of cam rotation for different designs of timing belt, and also consistency of cam rotation through the life of the timing belt (or chain). The improvements have been quantified from engine studies of engine efficiency, engine dynamics, engine friction measurements, accelerometer studies for NVH behaviour and from these the benefits in fuel economy and CO2 emissions were quantified. Novel systems that use a timing belt running within the engine immersed in oil are discussed. These have been adopted on two engines to date, with significant interest and development projects under way. Of concern to the motorist are not only fuel efficiency but also the cost and frequency of changing a timing belt. The historical mechanisms will be discussed of the changes in timing belts that control the belt durability. The improvements in reinforcing cord design and performance that contribute to life-of-engine belts will be presented, together with cord and belt developments that increase the durability and reliability of the timing belt even further.
A method for reducing friction loss in the engine timing chain was investigated using multi-body dynamics simulation. The method known as the link-by-link model was employed in the simulation to enable representation of the behavior of each single link of the chain and its friction due to contact. In order to predict the friction under actual engine operating conditions, a model that takes camshaft torque fluctuation and crankshaft rotational speed fluctuation into account was created. This simulation was used to verify the detailed distribution of friction in each part of the chain system as well as the changes of friction in the time domain. As a result, it was found that the sliding friction in the chain tensioner guide and chain guide was larger than in other locations. Based on this result, a method of reducing friction entirely by measures in mechanisms and structures without relying on low-friction materials was investigated. Simulation was used to verify the predicted effects of these measures, with the result that reducing the moment of inertia of the camshaft and reducing the initial load on the chain tensioner were confirmed to reduce friction loss.
Engine efficiency and optimization are key aspects for automotive manufacturers. Lamborghini has particularly focus attention for reduction of time to market building up a synergic approach for new component's development using simulation, Know-how experiences, engine engineering expertise and experimental validation. In particular to reach the best results in the shortest time it is used, in the preliminary stage of development, a massive support of simulation analysis. In the Lamborghini approach analysis and simulation has become key aspects during concept and development of timing drives. This type of activity is used to support the development of better chain timing drives focusing on improving durability, lower friction, less noise and reduced cost in less time than conventional trial and processes. Even during the concept design phase it is useful to use a mathematical model to calculate dynamic forces and motions of a chain drive. These models are used to assess in detail the choice of drive layout, to check that component load limits are not exceeded and to make a first choice of the tensioner settings. Later, when the first prototype engines are available, measurements of timing drive sprocket motion, tensioner motion and tensioner force are typically taken. At this stage the model can be correlated to the measured data and then the correlated model can then be used to explore the potential for improvements to the timing drive during later phases of engine development. This paper describes the correlation of a mathematical model of a complex timing chain drive for a Lamborghini V12 gasoline engine to measurements made on a prototype engine. The depth of model required and the choice of stiffness and damping values needed to give excellent agreement between calculations and measured data are discussed.
This paper describes Kappa dual CVVT (Continuously Variable Valve Timing) gasoline engine that Hyundai has developed for small cars lately. This engine is produced at engine plants in India and South Korea. This engine has been installed in small passenger cars named "i10," "i20," "Picanto," etc., and introduced into world market including Europe and India. Nowadays, car makers in the world have been competitively developing small cars in order to cope with rising oil price and becoming more stringent CO₂ emission regulations. The new engine has been introduced into market since November 2010. Main development goals of this engine were to reduce CO₂ emission and improve fuel economy. As a small engine, it was also developed in consideration of generous engine torque, lighter weight, minimal noise, lower cost and compact size. This paper presents various technologies featuring higher torque, better fuel efficiency, lower noise level and lighter weight. Major items for technical highlights are as follows: - Dual CVVT, Roller swing arm, offset crankshaft, beehive valve spring, MoS₂-coated piston and low tension piston rings for saving fuel consumption. - DOHC(Double Over Head Camshaft) 16V, long runner intake manifold, M12 long reach spark plug and valve timing optimization for excellent torque at low and middle engine speed. - Ladder frame, hydraulic lash adjuster and silent timing chain to reduce the noise. In addition, to reduce weight this engine is equipped with aluminum cylinder block, plastic cylinder head cover, plastic intake manifold, etc.
Fully variable valve trains provide comprehensive means of adjustment in terms of variable valve timing and valve lift. The efficiency of the engine is improved in the operating range and in return, an increasing complexness of the mechanical design and control engineering must be handled. For optimization and design of these kinds of complex systems, detailed simulation models covering different physical domains, i.e. mechanics, hydraulics, electrodynamics and control are needed. Topic of this work is the variable valve train named Audi valvelift system (AVS) e.g. used in the Audi 2.8l V6 FSI engine. The idea of AVS is to use different cam lobes at different operating points. Each intake valve can be actuated by a large and a small cam. For full load, the two inlet valves are opened by the large cam profile - ideal for high charge volumes and flow speeds in the combustion chamber. Under partial load, the small cam profiles are used. As a result, the gas exchange improves, throttling losses are minimized and fuel consumption is reduced. To investigate the dynamical behavior and interactions between all subsystems, e.g. between chain vibrations and shifting events, an overall simulation model comprising the timing chain drive, chain tensioner, hydraulic cam phasing system, valve train and the AVS system including the electromagnetic actuator has been derived. For modeling and simulation of the different subsystems, several highly specialized and efficient programs are used. To couple these subsystems co-simulation techniques are applied with the advantage that all subsystems can be computed in parallel on multi-core architectures to speed up integration time making optimization possible. In this paper a dynamical analysis of the entire AVS valve train including the electromagnetic actuators combining experiments and simulation is presented. The simulation model is described and validated with experimental results using different test rigs. Furthermore, interactions between the subsystems and optimization results are presented.
A theoretical evaluation technology for timing chain systems in single-cylinder engine has been established. Hitherto, there have been almost no theoretical evaluation reports published about drive loss and slapping noise in cam drive systems including timing chains. Thus, tensioner lifter and tensioner guide specifications to satisfy requirements related to slapping noise and friction loss have been determined only by tests with actual engines. In this research, a highly accurate mechanism-simulation model has been constructed that takes into account factors such as dynamic characteristics along with crank sprocket and timing chain contact stiffness and friction coefficient in addition to static characteristics of the timing chain and tensioner guide. Our results have confirmed a high correlation with actual engine tests at an absolute value level. This research has allowed a review at the early design stages of timing-chain systems that combine improved fuel efficiency with quietness and other engine performance factors at a high level.
The fourth generation of Lexus' global flagship sets new standards in engineering, technical innovation, refinement, and workmanship. “Yet again, Toyota demonstrates excellence in execution, not only in the basics, but also in the introduction of new active safety technologies in advance of their competitors,” one reader wrote, in describing the Lexus LS 460, Automotive Engineering International's Best Engineered Vehicle for 2007. “Transmission, engine, steering, chassis, fuel system, and driver monitoring systems are all new-and represent significant advances over the previous model,” said another.
Buoyed by much improved quality and customer satisfaction, Hyundai looks to move upmarket, develop its own hybrid vehicles, and invest in the future. The long-awaited opening of its first U.S. manufacturing plant in Montgomery, AL, could pave the way for a dramatic turning point for the ambitious Hyundai Motor Co., which is trying to further boost its car quality through engineering and manufacturing upgrades in new cars. Once known as a byword for poor quality cars, South Korea's leading automaker, and owner of the second-largest, Kia Motors Corp., believes the Alabama plant that officially opened in May will also help it achieve its long-term goal of emerging as one of the top five automakers by 2010. With the historic opening of the Montgomery plant, Hyundai adds to its range of automotive capabilities in the U.S. Its research and design center, sales and marketing operations, and full-scale test track are located in California, whereas an engineering center is located in Michigan. With the addition of the Montgomery plant, Hyundai will be able to provide complete services from production to sales. The Montgomery plant is armed with state-of-the-art stamping and welding facilities, paint department, in-house engine shop, and test track.
Existing VDR mechanisms have not progressed beyond the ground test experimental stage partially due to their inability to achieve the weight, reliability and maintainability requirements for practical aircraft application. Recent advancements in digital flight control systems and Health Usage Monitoring however can be applied to make a Variable Diameter Rotor (VDR) mechanism practical. Current published VDR design concepts do not integrate with existing rotor hub designs since their mechanisms occupy the space normally used by the rotor hub's structure and constant velocity joint. Many of these designs require a rigid hub configuration to maintain alignment of their VDR mechanism gearing. By using separate differential planetary rotary transmissions at each blade and interconnecting them with flexible timing belts, the mechanism described in this paper integrates with most existing rotor hub design configurations. This paper studies the application of system control and mechanical power transmission technologies to create a practical VDR mechanism for the BA609 three bladed rotor. A historical review of VDR studies and experimentation performed by Bell between 1962 and 1971 provides an introduction to the technical issues facing the development of a practical VDR mechanism design.
The new 2005 Pathfinder is built on a more rugged body-on-frame platform and features a more powerful V6 and three-row seating. When it was first introduced in 1986, the Pathfinder was the lone SUV in Nissan showrooms in North America. Today the company has SUVs in many shapes and sizes including the full-size truck-based Armada and compact Xterra as well as the car-based Murano. This model variety has allowed the third-generation Pathfinder to return to its body-on-frame truck-based roots from the second-generation's unibody construction. The new model, which went on sale last month, will compete with the likes of middle SUV segment contenders such as the Toyota 4Runner, Ford Explorer, Chevrolet TrailBlazer and GMC Envoy, Dodge Durango, and Jeep Grand Cherokee. Four- and rear-wheel drive will be offered, with Nissan expecting that 70% of customers will opt for the former. The company also projects the take-rate on the four trim levels to be 15% XE (value), 30% SE (value/popularly equipped), 15% SE Off-Road (performance), and 40% LE (fully equipped). The new Pathfinder, along with the new Frontier pickup and smaller Xterra SUV, is the result of the largest investment in a new vehicle platform in the history of Nissan. All told, the program involved a $2.4 billion dollar investment and the participation of all three Nissan technical centers in Japan, the United States, and Europe. Variations on the program's products will be sold in 32 countries.
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