Cylinder Head Research Articles

Characterization of a Cast Al-Cu Alloy for Automotive Cylinder Head Applications

Characterization of a Cast Al-Cu Alloy for Automotive Cylinder Head Applications

2-Stroke RCCI Engines for Passenger Cars

Reactivity Controlled Compression Ignition (RCCI) is one of the most promising solutions among the low temperature combustion concepts, in terms of thermal efficiency and pollutant emissions. However, for values of brake mean effective pressure higher than 10 bar, in-cylinder peak pressure rise rates tend to be too high, limiting the specific power of any 4-Stroke (4S) engine. Such a limitation can be canceled by moving to the 2-Stroke (2S) cycle. Among many alternatives, the “Uniflow” scavenging system with exhaust poppet valves on the cylinder head allows the designer to reproduce the same identical combustion patterns of a 4-stroke RCCI engine, while increasing the indicated power output. The goal of the paper is to explore the potential of a 2-stroke RCCI engine, on the basis of a comprehensive experimental campaign carried out on a modified automotive 2.0 L, 4-stroke, four-cylinder, four-valve diesel engine. The developed prototype can run with one cylinder operating in 4-stroke RCCI mode (gasoline–diesel), while the others work in the standard diesel mode. A One Dimensional-Computational Fluid Dynamics (1D-CFD) model has been built to predict the performance of the same prototype, when operating all four cylinders in RCCI mode. In parallel, an equivalent 2-stroke RCCI virtual engine has been developed, by means of 1D-CFD simulations and empirical assumptions. A numerical comparison between the 4S and the 2S engines is finally presented, in terms of performance and emissions at full load. The study demonstrates that a 2S RCCI engine can maintain all of the advantages of the RCCI combustion, strongly reducing the penalization in terms of performance, in comparison to a standard 4S diesel engine.

Study on scatter in mechanical properties of cylinder head with complex structure characters

The scatter of casting defects induced by the casting process causes the scatter of mechanical properties of cast alloys. The cylinder head of a high-power density engine is huge and complex, which frequently leads to fatigue behavior due to scattering and uncertainty of casting defects. A statistical approach is used to examine the mechanical properties at multiple places of a cylinder head with a complicated construction, including the top plate, the connecting wall, and the bottom plate, in order to determine the scatter of casting defects. A prediction model is built based on the pore of fatigue crack initiation and predicts the fatigue life well. The findings show that the grain size scatters at different positions of the cylinder head correspond to tensile properties, while porosity scatters at the crack initiation site of fracture specimens from different positions of the cylinder head correspond to fatigue life. As a result, the microstructure of the complicated cylinder head at different sites is a major element influencing the spatial scatter of mechanical characteristics, which can be exploited to promote cylinder head optimization.

Approach to enhance the heat transfer of valve seats through thermal analysis

The valve seat insert is a component of the engine cylinder head, whose primary function is to seal the combustion chamber and absorb the valve's heat, releasing it to the engine cylinder head. The valves experience high temperatures owing to high thermal loading and low heat absorption in the valve seat, which can potentially damage the engine. Therefore, the thermal characteristics of the valve seat must be optimised to increase the heat transmission between the valve and its seat. Here, three copper alloy valve seats, brass, beryllium copper, and bronze copper, were tested against the existing sintered iron valve seat, and their temperature maps were determined using actual engine operation conditions. The instantaneous heat transfer coefficients of the valves, seats, and engine cylinder head during the four-stroke cycle were evaluated using a one-dimensional thermal simulation analysis. The values obtained were used to assess the finite-element model using a three-dimensional thermal simulation in the Ansys software. The results show that the brass, beryllium-, and bronze-copper valve seats increased the overall heat flux by 4.46%, 4.16%, and 2.06%, respectively, compared to those for sintered iron. Thus, the results are essential to improve the thermal characteristics of the copper alloy valve seat imposed on the cylinder head. For validation, an experimental engine thermal survey and uncertainty magnification factors were used to validate the model. The results indicate that the maximum difference between the simulation and experimental values is 8.42%. Therefore, this approach offers a direct and comprehensible application for evaluating the temperature distribution, heat gradient, and heat flux of the cylinder head of air-cooled spark-ignition moped motorcycle engines using copper alloy valve seat materials at intermediate engine speeds. Furthermore, this method is applicable as a platform for the automotive industry to improve the heat transfer of the structural parts of internal combustion engines.

Matching and Planning of Machining Process Based on Similarity Principles

In order to meet the requirements of intelligent and digital process planning, a similarity-based process planning method is studied. Firstly, the characteristics of part machining features and machining process are analyzed, and the representation and retrieval model of part feature cases is established; Secondly, the principle of process combination based on factory and parallel principle is put forward, and the clustering hierarchy method is used to combine the processes, and the process elements in the process family are sorted and combined to generate the part process. The feasibility of this method is verified by an example, which can realize the digital design of machining process for complex parts such as engine cylinder block and cylinder head, thereby realize high-precision flexible machining.

Ventilation Analysis of Simplified Engine Nacelle for Pusher Aircraft

The paper contains the results of CFD analysis of flow inside the simplified engine nacelle, containing the engine in a pusher configuration. The authors have tested a set of solutions to increase an efficiency of the cooling system of this type of engine. Unfortunately, all the positive effects of the fact, that the aircraft engine appears in the wake of the propeller during taxiing and waiting for takeoff, are nonexistent in this type of configuration. An engine overheating is here a problem, because an airflow has to be pulled through the nacelle to cool down the engine block and radiators of cylinder heads. That design demands to analyze the cover shape of the nacelle, to properly use the main propeller pressure jump on the one hand, and rather adequate and complicated flow inside the nacelle to be modelled on the other. The aircraft CAD geometry has been simplified to allow for simple changes of the nacelle cover shape and easily introducing new inlets and outlets. The results prove, that the proper application of scoops gives even better result, than simply removing the cover and baffles from the engine. The exhaust scoops should be placed near the propeller plane in such pusher configuration, because the engine is not covered by the propeller wake.

FSI simulation of the suction valve on the piston for reciprocating compressors

The suction valve is an essential one-way valve inside the reciprocating compressor controlling the suction gas flow. It is usually installed on the cylinder head of the compressor. However, the suction valve in oil-free mini compressors was preferred to be installed on the piston to cool down the bearing inside the piston by the suction flow. In this case, the motion of the piston will act varying accelerated speed on the valve plate. During its opening process, the valve plate would be pushed by resultant force of the inertia force generated by the accelerated speed and the flow thrust together. It would result in too high valve lift and deformation, and decrease the reliability of the valve plate extremely. For this reason, the stiffness of the valve on the piston should be greater than that on the cylinder head. However, stiffness strengthened valve plate moving with the piston would behaves oscillation motion during its opening and closing process. In this paper, a three-dimensional fluid-structure interaction (FSI) model validated by experiments was established using ADINA to study the oscillation motion of the valve installed on the piston. Obtained results showed that the lift integral of the valve on the piston was 4.5% less than that of the valve on the cylinder head, and the impact speed on the valve seat of the valve on the piston was smaller than that of the valve on the cylinder head, which indicated that the suction valve installed on the piston had higher reliability.

Exhaust Gas Recirculation on a Nano-Coated Combustion Chamber of a Diesel Engine Fueled with Waste Plastic Oil

Managing waste plastic is becoming a severe challenge. The industry and researchers have been looking at various opportunities in line with circular economy principles for effective plastic waste management. In that context, plastic waste valorization to oil as a substitute to fossil fuel has gained recent attention. In the literature, there exist few studies showing the use of oil derived from waste plastics in blends with other conventional fuels in compression ignition (CI) engines; however, studies on CI engines that use 100% waste-derived fuels are limited. Additionally, the exhaust gas recirculation (EGR) concepts and the use of nano-coated chambers (like pistons, valves and cylinders heads) have been gaining interest purely from the engine performance enhancement perspective in recent years. Therefore, this study investigates engine performance by combining exhaust gas from the EGR technique and waste plastic oil (WPO) as inputs, followed by thermal coatings in the CI engine chambers for performance enhancement. The experimental setup of the engine is developed, and the engine’s piston, valve and cylinder heads are coated with Al2O3-SiO4 material. The CI engine’s energy, emission, and combustion characteristics are tested, followed by a scenario analysis compared with diesel-only fuel. The tested scenarios include a WPO + Al2O3-SiO4, WPO + Al2O3-SiO4 + 10% EGR, and WPO + Al2O3-SiO4 + 20% EGR. The results show that the piston crown’s thermal coating increased the combustion performance. Significant impacts on the carbon monoxide, hydrocarbons, and smoke characteristics are observed for different %EGR rates. The results also showed that the cooled EGR engine has decreased nitric oxide emissions. Overall, the results show that WPO combined with exhaust gas could be a potential fuel for future CI engines.

An experimental investigation on performance of converted CNG engine by varying piston bowl geometry: A case study

ABSTRACT Using natural gas as an alternative fuel will be reduced exhaust emissions and dependence on petroleum. The practical solution for Vietnam’s conditions is to convert diesel engines into natural gas engines. Understanding the effect of piston geometry on the performance of converted CNG engines helps domestic manufacturers come up to spark ignition natural gas engines with high performance and low emission. In this work, three different types of combustion chamber were made from milling piston head and varying thickness of cylinder head gasket. The experiment results showed that torque and power of ε = 11.5 were more significant than ε = 12.5. During experiment processes, the stable operation state of the converted engine with ε = 12.5 was challenging to control, and the noise levels were intense. The results of mass fraction burned were presented the effect of squish gap on performance was more substantial than that of the squish area. It can be concluded that for modifying the original diesel engines to run on CNG fuel, the maximum compression ratio should be set to 12.5 and must be redesigned accordingly to use the natural results. Implications: This manuscript shows the new technology to convert traditional engines into engines fueled by renewable energy. It contributes to reducing the fossil fuel crisis and environmental emissions.

Identification of start of combustion based on contribution level of principal component in vibration signal of cylinder head surface

The surface vibration signal measured from diesel engine cylinder head is caused by in-cylinder pressure (ICP) excitation and non-combustion excitations. These excitation response signals are coupled together, which increases the difficulty of identifying combustion information from the vibration signal. Furthermore, there always exists a phase deviation between the identified phase combustion parameter and the theoretical value, which decreases the recognition accuracy of combustion parameter. To accurately extract the combustion information, this paper firstly simulates the vibration signal caused by the combine of ICP, piston side pressure, piston slap and reciprocating inertial force of an SD2100TA diesel engine. Then, the principal component analysis (PCA) is introduced to analyze the contribution level of the combustion excitation response signal in the vibration signal under different working conditions. Meanwhile the influence of measuring point position and number on the contribution level is also discussed. Results show that the contribution level decreases gradually with the increase of the rotation speed and slightly increases with the increase of the torque. In addition, the contribution level is higher when the measuring point is farther away from adjacent cylinder. Finally, the relationship between the contribution level and the identified phase deviation of the start of combustion (SOC) is analyzed, and the deviation correction method is proposed. Results show that the maximum error of SOC after correction is within ± 1 deg.

PENGARUH CELAH CAMSHAFT TERHADAP NOISE PADA CYLINDER HEAD HONDA CB 150 R

Noise on a motorcycle is unwanted sound because it does not fit the context of space and time thus affecting ride comfort . Noise caused by the vibrating object or objects collide . Which became the main object causes of noise in the Cylinder Head Honda cb 150 R is due to the large gap camshaft causing collision between the camshaft with holder.
 This research was conducted entirely in the workshop by examining the influence of several variations of the gap camshaft to noise generated in the cylinder head . Variations slit used was 0,75 mm , 0,85 mm , 0,95 mm , 1,05 mm, and 1,15 mm . The results showed that the variation of the gap camshaft significant effect on the noise generated , namely : a gap of 0,75 mm camshaft generate noise by 78,12 dB , 0,85 mm gap camshaft generate noise with a value of 78,37 dB , 0,95 mm gap camshaft generate noise 78,93 dB , 1,05 mm gap camshaft generate noise levels at 79,95 dB, and 1,15 mm gap camshafts produce 80,23 dB.
 Based on the results of the research with camshaft gap variation can be concluded that the lowest noise level generated by the camshaft gap of 0,75 mm .

A Computational Fluid Dynamics Investigation Comparing the Performance of an Alternative Valvetrain Design Against a Traditional Poppet Valvetrain

Abstract The poppet valve is by far the most widely used in cylinder head design of internal combustion (IC) engines; however, poppet valves themselves create significant flow restrictions during both the intake and exhaust strokes, thus causing a reduction in volumetric efficiency that affects overall engine performance. By removing the restrictive poppet valve from the flow path of air into and out of the cylinder head and allowing air to flow unobstructed, any given IC engine can achieve greater volumetric efficiency and higher specific output. The Vaztec ECOREV rotary valve system utilizes straight-cut flow passages that reduce such restrictions. This rotary valve system is designed to be directly driven by the crankshaft, thereby replacing the camshaft and poppet valve system altogether. This paper will primarily explore the differences in flow characteristics between this rotary valve and a conventional poppet valve cylinder head using both computational fluid dynamics (CFD) and flow bench data. Both configurations will be evaluated on the same single-cylinder four-stroke internal combustion engine. CFD simulations were run at multiple valve opening positions on each cylinder head configuration for both intake and exhaust cycles to validate the CFD process against flow bench test data for both cylinder head designs. The CFD was performed in 3D using hexahedral meshing and steady-state Reynolds-averaged Navier–Stokes (RANS) turbulence models. Comparison between the two engine configurations will include both intake and exhaust airflow rates as well as discharge coefficients and overall flow field evaluation using numerous scalar and vector properties.

Evaluation of the partitioned mechanical properties and the hall-petch relationship of cast aluminum alloy cylinder head

In view of the non-uniform distribution of mechanical properties of cast aluminum alloy cylinder head, the mechanical properties evaluation and microstructure heterogeneity of cylinder head were studied. The results showed that the head plate position of the cylinder head has the best mechanical properties and microstructure characterization, followed by the floor plate and the thick partition plate. The mechanical properties of the floor plate position attenuate with increasing temperature. From 23°C to 300°C, the tensile strength and yield strength decrease in the same range, but the break elongation changes most obviously. The mechanical properties and microstructure characterization of cylinder head in-situ sampling satisfy the Hall-Petch relationship. If the required ultimate tensile strength is not less than 255MPa, the upper threshold of the grain size, by considering the error limit of the Hall-Petch relationship, is 603.4μm, and the upper threshold of secondary dendrite arm spacing is 69.1μm. Meanwhile, established the relationship between hardness and yield strength, the average error of the nonlinear model is 4.35%. The prediction accuracy of the nonlinear model is sufficient to meet the actual needs of the engineering.

The microstructural and wear properties improvement by manganese addition in Al-14Si hypereutectic alloy

Hyper eutectic Al-Si alloys, which are a great candidate for aerospace and automotive industries and are utilized to manufacture engine blocks, cylinder heads and pistons, rocker arms and fraction plates, all of which can reduce and improve vehicle emissions. The goal of this investigation is to make an Al-14Si alloy with different proportions of manganese as an addition to produce a composite using the stir casting method. The effect of manganese in microstructure and impact on the morphology of silicon, both primary and eutectic was highlighted in this paper. The amorphous form of silicon (primary) and silicon (eutectic) is changed to the fine globular shape of primary Si and fibrous and numerous fine eutectic Si. With the inclusion of Mn, the mechanical properties and wear characteristics of the composites are determined. Increase in manganese content decreases the wear rate in Al-14Si-1.5Mn.The microstructural-properties relations are co-related utilizing the addition of manganese into the Al-14Si alloy.

Fatigue software improvement for calculating by FEA a complete map of the damage due to a duty cycle, regarding thermo-mechanical failure mode.: Application to a truck cylinder head lifetime assessment

Physical tests considering real customer usages for truck engine components durability validation, are very expensive and time consuming. Using a calculation method enabling to determine cumulative damage due to a specific duty cycle, seems then a priority, especially for fatigue thermo-mechanical failure mode.However, most of these complex engine components have several brittle areas, and the current calculation methods within Volvo GTT France allow only to analyze one or few critical areas, without considering the complete behavior of the component in the analysis.With the improvement of the tool Sofast, realized through a partnership between Volvo GTT France and Arobas Technologies, it is then now possible to calculate by FEA the complete damage field on a specific component regarding thermo-mechanical failure mode.In this paper, one industrial example is detailed, to show the effectiveness of the methodology: a damage analysis of a truck cast iron cylinder head.

Combustion chamber geometry and fuel supply system variations on fuel economy and exhaust emissions of GDI engine with EGR

In this study, the combustion chamber geometry for spray-guided, wall-guided, and air-guided combustion strategies were fabricated. The piston crown shape and the cylinder head in each combustion chamber geometry was machined by fixing the fuel injector and spark plug at proper positions to obtain swirl, turbulence, and squish effects for better mixing of fuel with air and superior combustion of the mixture. Conducted tests on all the three modified gasoline direct injection engines with optimized exhaust gas recirculation and electronic control towards fuel injection timing, the fuel injection pressure, and the ignition timing for better the performance and emissions control. It is clear from the results that NOx emissions from all three combustion modes were reduced by 4.9% up to 50% of loads and it increase for higher loads due to increase of in-cylinder pressure. The fuel consumption and emissions showed better at 150 bar fuel injection pressure for wall-guided combustion chamber geometry. Reduced HC emissions by 3.7% and 4.7%, reduced CO emissions by 2% and 3.3%, reduced soot emissions by 6.12% and 10.6%. Reduces specific fuel consumption by about 10.3% and 13.3% in wall-guided combustion strategy compare with spray-guided and air-guided combustion modes respectively

Analysis of the cylinder head for a spark ignition engine using zonal cooling principle

In the paper, it is performed a detailed thermo-structural analysis of the cylinder head for a spark ignition engine using the zonal cooling principle. The zonal cooling principle assumes two cooling circuits, one for the cylinder head and one for the cylinder block and a continuous adjustment of cooling temperature in accordance with the working principle. By using this principle, it is considered the possibility of using higher values of the volumetric compression ratio, leading to the increase of the engine performance. Thus, the reduction of the temperature of the fresh air fuel mixture in the intake channel and the lower temperature of the fresh air fuel mixture, when getting in contact with combustion chamber walls, leads to a delay of self-ignition and finally the detonation can be suppressed. Due to the possibility of using a higher compression ratio, the thermo-structural analysis was performed using ANSYS Workbench.

Intelligent Detection Method of Forgings Defects Detection Based on Improved EfficientNet and Memetic Algorithm

In the process of production, automobile steel forgings are prone to various cracks, which affect the product quality. At present, forgings defects are mainly detected by fluorescent magnetic particle inspection and manual inspection. Aiming at the problems of low detection accuracy and efficiency in this method, an improved convolutional neural network model is proposed. The fluorescent magnetic particle inspection images of two typical forgings were intelligently inspected. Firstly, a deep learning model with EfficientNet as the backbone and Feature Pyramid Network (FPN) as the fusion layer is constructed. Secondly, In order to improve the convergence speed and detection accuracy, the calculation method of intersection over union is improved, and the network is improved by using the Attention Mechanism. Finally, Particle Swarm Optimization algorithm (PSO) with adaptive parameters is introduced to optimize the hyperparameters of neural network, and a fluorescent magnetic particle inspection image acquisition platform is built for verification. The mean Average Precision (mAP) of the best model of EfficientNet-PSO on the validation set is 95.69%. F1 score is 0.94 and FLOPs is 1.86B. Compared with other five deep learning neural network models, this method effectively improves the defect detection efficiency and accuracy of flange plate and cylinder head, which can meet the defect detection requirements.

Diagnosis of Thermal Overload and Power Losses in Boat Yang 1’s CAT 3408 Marine Diesel Engine from Used Oil and Coolant Analysis

In the design of the CAT 3408 engine, the Low Temperature (BT) circuits used to cool the engine lubricating oil and the charge air and the High Temperature (HT) circuits for cooling the cylinder liners, cylinder heads and body of turbofans are mainly used to cool the engine, so that it works properly. This work, based on the analysis carried out, to determine the lubrication compliance of the Yacco VX 100 - SAE 15 W-40 oil and that of the Camwater water used in the engine of the Boat Yang 1 by carrying out a series of conventional tests such as that: the density, the viscosity, the viscosity index, the flash point, the density, the sulphate center content, the water content, the total acidity index (TAN), total basic number (TBN) and pour point for the oil case and pH, hardness, sodium chloride content [NaCl], sodium sulphate content [NaSO4] for the water case which will be compared to the specified requirements to determine whether compliance is achieved for each of these characteristics. The results of the oil and water samples taken from the engine after use show that the used oil gives a specific gravity of 0.8822, a viscosity (at 40°C) of 92.29 mm2/s, a viscosity (at 100°C) of 13.99 mm2/s, a viscosity index (VI) of 155.39, a pour point -21°C, a Flash Point (VO) 215°C, a Sulfated ash content of 18%, a density 881.5 kg/m3, a total basic number (TBN) of 12.60 mgKOH/g, a Total Acid Index (TAN) of 3.096 mgKOH/g, a Water Content of 1.8 % and the water used gives a pH of 6.00, a hardness of 3.2 french degrees, a sodium chloride content [NaCl] of 0.468 mg/L, and a calcium sulphate content [CaSO4] of 2.38345 mg/L. the results of the water content and content of sulfated centers justify the thermal overload and power losses in the marine diesel engine CAT 3408 of the boat Yang 1 because of their values which are not in conformity with the standards.

Maintenance of the N47 Internal-Combustion Diesel Engine

The N47 engine debuted in March 2007 in the facelifted BMW 1 Series E87 and E81 and was also available in the BMW 1 Series E82 and E88, which were introduced the same year. The N47 engine replaced the M47 engine that had been in production for 8 years. The M47 construction underwent several modifications, so the injection system was changed, the cylinder head now consists of two parts, and the engine block is made of aluminium. Two main versions of the N47 engine are known: N47D16 (1.6 L) and N47D20 (2.0 L). In the case of both versions, several models with different performances were born. After the distribution of BMW passenger cars equipped with the N47D20 engine, it received a lot of negative criticism due to malfunctions. In this article, I would like to present the maintenance of the engine, which can be used to avoid the failure of passenger cars equipped with the N47D20 diesel engine with huge material damage.