Browse Topic: Camshafts
During a recent Bosch tech showcase, we spoke with Joe Dear, engineering manager for electric propulsion systems at Linamar. The Guelph, Ontario-based parts manufacturer is no stranger to building unsung components for the auto industry, including gears, camshafts, connecting rods, and cylinder heads. The Linamar team was demonstrating a modified Ram 2500, a collaboration between Bosch and Linamar, that was outfitted with a prototype electric powertrain and new e-axles: a rigid axle on the rear (with a Bosch motor and inverter) and a steering axle up front
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
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
Scania Power Solutions has launched a new engine platform designed to provide new power outputs, longer service intervals, longer base-engine operational life and reduced carbon dioxide emissions. The engines will be available for industrial, heavy machinery and power generation applications. Series production is due to begin in 2024. The starting point for the new platform is the 12.74-liter inline six-cylinder diesel engine designed for Scania's road-going vehicles, which was launched in late 2021. This engine delivered a claimed reduction in fuel consumption of 8% and thermal efficiency approaching 50%. Design features include dual overhead camshafts and a single cylinder head casting, replacing the individual cylinder heads of the previous engine
This document describes methodologies to determine the causes blow-by oil consumption caused by the power cylinder
Hydrogen may be used to feed a fuel cell or directly an internal combustion engine as an alternative to current fossil fuels. The latter option offers the advantages of already existing hydrocarbon fuel engines - autonomy, pre-existing and proven technology, lifetime, controlled cost, existing industrial tools and short time to market - with a very low carbon footprint and high tolerance to low purity hydrogen. Hydrogen is expected to be relevant for light and heavy duty applications as well as for off road applications, but currently most of research focus on small engine and especially spark ignition engine which is easily adaptable. This guided us to select modern high-efficient gasoline-based engines to start the investigation of hydrogen internal combustion engine development. This study aims to access the properties and limitations of hydrogen combustion on a high-efficiency spark ignited single cylinder engine with the support of the 3D-CFD computation. A high efficiency
The tests were carried out on an 3D engine model with an unconventional multiple linkage system. Compared to a classic crankset, the mechanism consists of more elements. In this multiple linkage system the camshaft, the piston rod and the main rod are connected to one common element. The camshaft rotating during operation at twice the speed of the crankshaft makes possible to achieve different piston stroke lengths with each revolution. With proper synchronization of the camshaft revolution with the crankshaft, the suction and compression stroke is smaller in relation to the expansion and exhaust strokes. For this reason, the Atkinson cycle was obtained without interfering with the variable valve timing. The thermal cycle is characterized by increased theoretical thermal efficiency. Due to the unique mechanism, the piston movement has different characteristics compared to classic solutions. Therefore, work was undertaken to analyze the distribution of forces in the system. For the
Nowadays, the vehicle hybridization and the use of non-conventional fuels for heavy-duty applications brings to a new beginning in the use of spark ignition (SI) engines. For a standard intake system, the premixed fuel/air mixture is controlled by the injection of fuel after the throttle valve. Then, the geometry of the intake system, with the intake duct, the intake valves and the cylinder head shape, influences the characteristics of the flow within the cylinder up to the combustion process. The new technology of fluid-power and electrical actuations gives the opportunity to decouple the intake and exhaust valve actuations with respect to the standard cam shaft distribution. The Variable Valve Actuation (VVA) concept is not new, but its application is now affordable and flexible enough to be applied to partial load conditions. In this work, the intake, compression and combustion processes of an SI engine are studied by means of a three-dimensional numerical approach based on a finite
The ever-increasing customer expectations put a lot of pressure on car manufacturers to constantly reduce the noise, vibration, and harshness (NVH) levels. This paper presents the holistic approach used to achieve best-in-class NVH levels in a modern high-power density 1.5 lit 4-cylinder diesel engine. In order to define the NVH targets for the engine, global benchmark engines were analysed with similar cubic capacity, power density, number of cylinders and charging system. Moreover, a benchmark diesel engine (considered as best-in-class in NVH) was measured in a semi-anechoic chamber to define the engine-level NVH targets of the new engine. The architecture selection and design of all the critical components were done giving due consideration to NVH behaviour while keeping a check on the weight and cost. Extensive 1D crank-train simulations were carried out to ensure that the crankshaft torsional amplitude was contained less than the NVH limit of 0.1 degree for higher-order
Commercial vehicles require continual improvements in order to meet fuel emission standards, improve diesel aftertreatment system performance and optimize vehicle fuel economy. Aftertreatment systems require significant space claim which makes vehicle packaging a challenge. Today’s diesel engines require valvetrain lash adjustment settings at distinct intervals to ensure proper valvetrain performance. This requires removing the engine rocker cover to access the valvetrain rocker arms for setting lash. Setting lash for compact vehicle applications sometimes requires removing the aftertreatment system to provide access to the rocker cover prior to setting lash. Then, the rocker cover is reinstalled followed by the aftertreatment system making the lash setting process time consuming and complex. This paper focuses on the design, development and validation of adapting hydraulic lash adjusters (HLAs) into a type V (camshaft in block) diesel engine thus eliminating the lash adjustment
Knurling joint applied in assembled camshaft has developed rapidly in recent years, which have exhibited great advantages against conventional joint methods in the aspects of automation, joint precision, thermal damage, noise, and near net shape forming. Both quality of assembly process and joint strength are the key requirements for manufacturing a reliable assembled camshaft. In this article, a finite element predictive approach including three subsequent models (knurling, press-fit and torsion strength) has been established. Johnson-Cook material model has been used to simulate the severe plastic deformation of the material. The residual stress field calculated from the knurling process was transferred as initial condition to the press-fit model to predict the press-fit load. The predicted press-fit load, torque strength and displacement of cam profile before failure were calculated. The torque strength of the joint was twice higher than that of a typical passenger vehicle
This article presents a comparative study between two camshafts systems adapted to the single cylinder engine of a Supermileage vehicle in a fuel economy perspective. One system is from a Honda AF70E engine and the other is a new design. The new camshaft system was improved for fuel economy by developing a new camshaft that enhances volumetric efficiency while reducing friction losses. The comparison was made by measuring the efficiency of the engine in the speed range where the engine was used by the Supermileage vehicle and a calculation was made to show which configuration is best for the vehicle
The engine efficacies require the blend of friction reduction approach for optimising the attained output. The research elucidates the scope of friction reduction mechanism to increase engine power and life. The engine components piston and piston rings are coated with the unique composite of graphite, molybdenum disulfide, tantalum layer to reduce friction and wear. The coating on piston minimizes direct contact between piston and cylinder liner, which reduces friction, BSFC and lead to better thermal stability, and engine life. The research also focuses on friction reduction of camshaft bearing by replacing sliding contact bearing with low friction roller bearing. The friction between engine components reduces output power, and the engine oil temperature plays a significant role in it. The research empowers zirconium dioxide coating on oil sump in order to reduce the temperature decay rate so that the optimized engine oil temperature of 100 °C can be retained for longer time. The
Research on turbocharging for FSAE at the University of Malta, has been ongoing for a number of years. 1D simulations were done to determine best design configuration and determine a lowered compression ratio. A decompression plate was installed on the Kawasaki 600 cc engine. Calibration of the engine was performed on the engine dynamometer. A hot-gas test stand for testing of the turbocharger was developed. The turbocharger speed was measured by a custom built hall-effect sensing setup that is compact enough to be implemented also in the FSAE vehicle. Bespoke camshafts with optimized valve timing determined through WAVE 1D simulations and designed with Valdyn® were machined. The turbocharged setup was used on the University of Malta FSAE vehicle in the FSAE Italy 2017 competition. Knock was investigated through in-cylinder pressure measurements and use of commercial knock sensor on the 600 cc engine. Benchmarking in-cylinder pressure measurement tests were carried out on a 1.4 liter
The demand for improving fuel economy in passenger cars is continuously increasing. Eliminating energy losses within the engine is one method of achieving fuel economy improvement. Frictional energy losses account for a noticeable portion of the overall efficiency of an engine. Valvetrain friction, specifically at the camshaft interface, is one area where potential for friction reduction is evident. Several factors can impact the friction at the camshaft interface. Some examples include: camshaft lobe profile, rocker arm interface geometry, valve spring properties, material properties, oil temperature, and oil pressure. This paper discusses the results of a series of tests that experimented the changes in friction that take place as these factors are altered. The impact of varying testing conditions such as oil pressure and oil temperature was evaluated throughout the duration of the testing and described herein. Test data quantifying the effect of utilizing friction reducing surface
In a previous report, it was shown that power transmission through the camshaft reduced the first mode natural frequency of the power train and translated its convergence with dominant engine excitatory harmonics to a lower engine speed resulting in a marked reduction in torsional vibration while achieving 2/1 gear reduction for a 4-stroke 6-cylinder compression ignition (CI) engine for aviation. This report describes a sweep though 2 and 4-stroke engines with differing numbers of cylinders configured as standard gear reduction (SGRE) and with power transmission through the camshaft (CDSE) or an equivalent dedicated internal driveshaft (DISE). Four and 6-cylinder 4-stroke engines were modeled as opposed boxer engines. Four and 6-cylinder 2-stroke engines and 8, 10 and 12-cylinder 2-stroke and 4-stroke engines were modeled as 180° V-engines. All 2-stroke engines were considered to be piston ported and configured as SGRE or DISE. All 4-stroke engines were configured as SGRE or CDSE. Mass
In this study, a finite element analysis method is developed for simulating a camshaft cap punching bench test. Stiffness results of simulated camshaft cap component are correlated with test data and used to validate the model accuracy in terms of material and boundary conditions. Next, the method is used for verification of cap design and durability performance improvement. In order to improve the computational efficiency of the finite element analysis, the punch is replaced by equivalent trigonometric distributed loads. The sensitivity of the finite element predicted strains for different trigonometric pressure distribution functions is also investigated and compared to strain gage measured values. A number of equivalent stress criteria are also used for fatigue safety factor calculations. The severity of the loading experienced by the camshaft caps depends on whether the under study cap is on intake or exhaust camshaft side as well as the location of the associated cylinder on the
In this paper, a simultaneous design and development work for a diesel engine valvetrain system is presented. The rocker arm is one of the most important components of the valvetrain system which is transmitting the energy between the valves and the camshaft. Valvetrain system becomes even more complicated, when the extreme high speed of the system and nonlinear character of combustion is combined with the unpredictable behavior of the hydraulic lost motion mechanism during engine brake. As the complexity increases, it gets harder to predict valvetrain stress values especially while engine brake is in action. By taking all of these effects into account, that is reducing reliability of virtual analysis, requirement to conduct a strain measurement on valvetrain became inevitable. Therefore the challenge to make instrumentation on a complete fast moving, lubricated system which operates around 140°C and to select a proper location that can reflect the right stress values is solved by
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