Engine Exhaust Valves Research Articles

Valves materials for internal combustion engines

The main strategy for improving the efficiency of internal combustion engines is to increase the cylinder pressure, which inevitably leads to increased mechanical and thermal stress on key engine components, including the intake and exhaust valves. However, traditional materials used for engine valves today are being pushed to their limits. Thus, increasing the efficiency of the next generation internal combustion engines requires the development of new valve materials with a higher set of performance properties at elevated temperatures. The article discusses the operating conditions of engine valves and the requirements for valve materials. A comparative analysis of traditional Russian and foreign valve materials that are widely used today (martensitic and austenitic steels, nickel-based alloys) has been performed. It is noted that Russian standards for valve materials contain recommendations for the use of certain steels for engine valves, which have long lost their market positions abroad due to their inherent shortcomings. On the other hand, some foreign materials specially developed for exhaust valves of diesel engines are not produced by Russian industry. A review of new generation valve materials developed by leading foreign companies in this field to replace expensive nickel-based alloys was carried out. It is noted that the development of new domestic cost-effective valve materials capable of operating under conditions of higher temperatures and pressures in more aggressive environments is an important scientific and technical problem, the solution of which is necessary for the accelerated development of the Russian engine industry

Research on the generalisation method of diesel engine exhaust valve leakage fault diagnosis based on acoustic emission

As the core of power machinery, diesel engines often work in harsh environments. Considering the non-linearity variation and divergence in feature distribution among different operating conditions or types of engines, it is time-consuming and impracticable to collect adequate fault-labelled datasets, therefore a novel fault diagnosis approach is proposed for diesel engine valve leakage fault diagnosis to transfer from one operating condition or type (source domain) to another (target domain) to enhance the generalization of fault diagnosis. The acoustic emission signals for a specified time interval are used as the input of a one-dimensional convolutional neural network to extract discriminative features, three domain-adaptive algorithms are applied to form fault diagnosis models and compare them. The fault simulation experimental results illustrate that the proposed method achieves high accuracy in fault diagnosis across-operating condition and across-engine-type, and the generalisation performance of the proposed method outperformed that of traditional ones.

A Survey on the Oxidation Behavior of a Nickel-Based Alloy Used in Natural Gas Engine Exhaust Valve Seats

This study reports the oxidation behavior of a Ni-based alloy used in the manufacture of valve seats for automotive engine exhaust systems. Isothermal thermogravimetric analyses were carried out at temperatures of 660, 740, 860, and 900 °C under an oxygen atmosphere for up to 1 h. At 660 and 740 °C, only one stage was observed during the whole time studied. At this stage, the oxide layer was formed mainly by NiO + Cr2O3, following a linear oxidation law with a rate constant (Kl) on the order of magnitude of 10−6 kg/m2s and an apparent activation energy (Ea) of ~47 kJ/mol. At 860 and 900 °C, an identical first stage was observed with a transition to a different stage. In the second stage, the oxidation layer was composed of Cr2O3, and a parabolic oxidation law was followed with a rate constant (Kp) on the order of 10−8 kg2/m4s and Ea of ~128 kJ/mol. Moreover, the Ni-based alloy formed a dense and compact oxide layer after oxidation, with no apparent cavities, pores, or microcracks. Characterization techniques such as Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), and Raman Spectroscopy were carried out to characterize the formed oxide layer.

Cyclic oxidation behavior of selected commercial NiCr-alloys for engine exhaust valves in wet air environment between 800 and 950 °C

The impact of water vapor on the cyclic oxidation behavior of four commercial Ni-based superalloys (N80A, N90, R41 and H282) was investigated between 800 and 950 °C. Oxidation- and volatilization-induced Cr loss accelerated the transition from protective and adherent oxide formation (Cr2O3) to mixed oxides that significantly spalled at 950 °C for H282 and R41. The accelerated oxidation, Cr depletion, and spallation susceptibility for R41 and to a lesser extent for H282 compared to N80A and N90 was related to the higher fraction of γ’, which led to increased Ti incorporation into the Cr2O3 scale in the presence of water vapor.

A Review of Coating Methods and Their Applications in Compression and Spark-Ignition Engines for Enhanced Performance

Coating of metallic surfaces such as cylinder heads, cylinder liners, piston heads and exhaust-valves in Internal Combustion Engines (ICEs) has improved engine performance in areas of brake-thermal-efficiency including brake-specific-fuel consumption, etc. This review showed different methods of coating in compression and spark-ignition engines for improved performance using different coating thicknesses on the metallic surfaces. These coating thicknesses may be either minimum or maximum depending on the coating method used. The coating methods discussed in this paper were Thermal Spraying (TS), Physical-Vapour Deposition (PVD), Chemical-Vapour Deposition (CVD) and Ion Implantation methods. Minimum thicknesses were achieved using the PVD, CVD and Ion-Implantation methods. In addition, Sol-Gel and Slurry coatings were also discussed. Having considered these methods of coating, thermal-spraying method was recommended for compression and spark-ignition engines because it produces temperature ranging from 8000 K-14000 K on surfaces with thick coating thicknesses.

One-Dimensional Modeling for Pulsed Flow Twin-Entry Turbine

Abstract One-dimensional (1D) modeling is critical for turbomachinery unsteady performance prediction and system response assessment of internal combustion engines. This paper uses a novel 1D modeling (TURBODYNA) and proposes two additional features for the application to a twin-entry turbocharger turbine. Compared to single-entry turbines, twin-entry turbines enhance turbocharger transient response and reduce engine exhaust valve overlap periods. However, out-of-phase high-frequency pulsating pressure waves lead to an unsteady mixing process from the two flows and pose great challenges to traditional 1D modeling. The present work resolves the mixing problem by directly solving mass, momentum, and energy conservation equations during the mixing process instead of applying constant pressure assumption at the limb–rotor joint. Comparisons of TURBODYNA and an experimentally validated CFD suggest that TURBODYNA cannot only provide a very good agreement on turbine performance but also accurately capture unsteady features due to flow field inertial and pressure wave propagation. Levels of accuracy achieved by TURBODYNA have proved superior to traditional 1D modeling on turbine performance and the generality of the current 1D modeling has been explored by extending the application to other turbine featuring distinct characteristics.

Investigating the thermal characteristic of copper alloys valve seat towards engine performance enhancement of MODENAS CT115 through steady-state analysis

MODENAS CT115 engine is a single overhead camshaft (SOHC) engine, with a rated power of 8.8 horsepower at 9000 rpm. One of the main concerns of engine research is the overheating of engines. Overheating can affects the performance of an engine by leading to a loss of strength and thermal strain. To prevent failure, thermal analysis is used to determine the flow of heat with precision to optimise temperature distribution. The investigation is done using ANSYS Thermal simulation on the CAD model of the engine cylinder head, intake and exhaust valve, and intake and exhaust valve seat insert. The comparison to the existing valve seat insert is made using three different valve seat insert materials: Beryllium-copper C17200, Bronze-copper C61300, and Brass C36000. The research results proved that Brass C36000 provides the best thermal reduction and heat transfer increment compared to the existing valve seat insert material.

Исследование гидродинамики смазки в зазорах механизма газораспределения двигателя внутреннего сгорания

The method of calculating the fluid dynamics of the lubricant in the gaps is considered on the basis of a generalized mathematical model of the dynamics of the gas distribution mechanism. The results of its use for the drive of the engine exhaust valve are presented. It is shown that the developed methods and algorithms provide a more accurate determination of the dynamic and tribological characteristics of the gas distribution mechanism.

Mechanical Behaviour of Al7075 Hybrid Composites Developed through Squeeze Casting

The automotive and aerospace sector are behind the development of squeeze casting process, as the squeeze cast components exhibit improved mechanical properties. Squeeze casting is a hybrid metal processing technique that combines the advantage of both casting and forging in one operation. The aluminium alloy 7075 is a futuristic material that is widely used to produce automotive and aerospace components. Cylindrical component of AL 7075 was produced by varying the squeeze pressure at certain level. The specimen was made from the component as per ASTM standard and they were tested for mechanical properties such as tensile hardness and impact strength respectively. It was found that mechanical properties were enhanced with increase in squeeze pressure. The aluminium 7075 hybrid composites developed through squeeze casting is fabricated and experimented upon and found to have adequate potential for wide variety of application. In aerospace industries it can be used in gear components, blade sleeves, guide vanes, wing components etc. Applications in surface transport are brake rotors, automotive engine cylinder, engine exhaust valve, body chassis and connecting rods. This material can be used in light weight applications such as power lines and wind mill fans.

Influence of Sulfur and Additives on Wear of Exhaust Valve Seat of Cylinder Head

In this paper, taking a certain type of high-power diesel engine exhaust valve abnormal wear phenomenon as an example, we conduct research on the exhaust valve surface micromorphology characteristics, contact surface accumulation products, additive transition layer, and combustion test. These passed diesel sulfur content comparative test, diesel additive composition analysis, and high-sulfur-content and low-sulfur-content diesel and diesel oil additive action test. At present, there is no authoritative research on the influence of sulfur content in diesel on valve seat wear of high-power diesel engines, and the protection mechanism of diesel additives on the valve seat is not clear. The sulfur in diesel, like the lead in gasoline, has long been known to resist wear in the valve seats of high-power diesel engines; just as gasoline additives compensate for the loss of lead, diesel oil additives seem to compensate for the loss of sulfur. Tests show that a uniform carbon deposition layer is formed on the contact surface after the diesel is burned, and the carbon deposition layer is more densely and uniformly adsorbed on the contact surface under the action of diesel additives to form an antiwear layer. Tests also show that the sulfur in diesel has no effect on the wear resistance of the valve seat.

Evaluating the efficacy of aluminide coatings to improve oxidation resistance of high performance engine valve alloys

Increasing peak cylinder pressures and operating temperatures of turbo-charged internal combustion engines (ICEs) engines present new challenges for existing materials employed in engine exhaust valves. Oxidation induced degradation of current Ni based alloys for these components will be a life-limiting mechanism while strict cost margins in the automotive transportation industry further limit the choice of suitable candidate materials. Metallic diffusion aluminide coatings can provide a cost-effective way to improve the oxidation resistance of underlying materials. In this study, the high temperature oxidation behavior of diffusion nickel aluminide coatings on two Ni based alloys (commercially available alloy 31V and a developmental alloy) during cyclic oxidation behavior in air+10% H2O at 900 °C was investigated. A complete depletion of the beneficial Al-rich β-(NiFe)Al phase was observed in the coating on alloy 31V while a significant fraction of this phase was retained in the coating on the second alloy. A coupled thermodynamic-kinetic model showed that the disappearance of the Al-rich phase in the coating on 31V was mainly due to the combined effect of steeper chemical potential gradients of Al and Ti between the coating and the substrate and their faster diffusivities compared to the coated developmental alloy. A higher content of Fe was shown to support the retention of β-(NiFe)Al phase in the coating on the developmental alloy while the presence of Ti in the alloy was shown to be detrimental for long-term coating performance.

Oxidation Behavior of Candidate NiCr Alloys for Engine Exhaust Valves: Part I—Effect of Minor Alloying Elements

Oxidation-induced degradation of structural materials employed as exhaust valves within internal combustion engines (ICEs) will be a relevant life-limiting mechanism, in addition to creep and mechanical fatigue, due to ever-increasing severity of operating temperatures and pressures. Ni–Cr-based alloys, which form external chromia-based scales at the relevant operating temperatures are being considered as suitable candidate materials. Thermal cycling of these alloys in water vapor-containing atmospheres, such as those present during hydrocarbon fuel combustion within ICEs, can considerably influence their oxidation behavior. In this study, the role of typical alloying additions such as Mn, Si, Al and Ti on the cyclic oxidation behavior of model NiCr–X (X = Mn,Si,Al,Ti) alloys exposed in dry air and air + 10% \(\hbox {H}_{2}\hbox {O}\) at \(800\, ^{\circ }\hbox {C}\) and \(950\, ^{\circ }\hbox {C}\) was investigated. Combined additions of Mn and Si reduced scaling rates compared to binary Ni–22Cr alloys. The presence of water vapor possibly suppressed formation of NiMnCr spinel and thereby the Cr depletion in the alloy. Combined Al and Ti additions mainly resulted in accelerated oxidation kinetics due to the Ti doping of chromia scales. More porous external scales were observed in water vapor leading to a much deeper depth of nitridation in the Ni–22Cr–Al–Ti alloys.

Cause Analysis and Preventive Measures of Cavitation Corrosion of Diesel Engine Exhaust Valve Seat

This paper analyses the formation of cavitation in the exhaust valve seat of marine diesel engine in combination with leakage of the exhaust valve seat. The paper mainly starts from the cooling water system of the diesel engine that affects cavitation. Finally, the paper puts forward some preventive measures of cavitation corrosion.

Experimental Studies on the Effect of Drilling Parameters on Monel Alloy

Monel K-500 is a Nickel based super alloy which have superlative properties such as high strength, resistance to corrosion, retention of mechanical properties at service temperature and structural stability. It finds wide application in aerospace application, nuclear reactor, gas turbines, submarines, combustion engine exhaust valve, petro chemical components, heat exchanger, etc. However, during machining of super alloys, difficulties are there due to its low thermal conductivity and work hardening effect. Challenges in conventional machining can be minimized by using suitable machining as well as process parameters. Among the different machining processes, not much work has been initiated on drilling of above super alloys. Normally, drilled holes are used in screws, bolts, shafts, steam pipes, fitting of furniture and other equipments. By considering the applications and difficulties in machining of super alloys, drilling experiment is selected on Monel K-500. Experiments were conducted as per Taguchi’s L9 orthogonal array using process parameters such as different drill tool material, drilling speed, feed and cutting fluids and Surface roughness and MRR values were measured as output responses. Effect of selected process parameters on the above machinability responses were analyzed. Optimum process parameters were identified to improve the machinability of Monel K-500.

Camshaftless Technology on Internal Engines

Along with the development of internal combustion engines, camshafts have also been developed to optimize engine performance. In all types of internal combustion engines, the crankshaft is connected to the camshaft via a toothed belt, chain or pinion. When the crankshaft turns, the camshaft spins and opens and closes the intake and exhaust valve respectively. However, in this non-camshaft engine technology, each intake and exhaust valve will be integrated with an electronically controlled hydraulic pump unit. This system provides a unique ability to independently control intake and exhaust valves. For any engine load, load and discharge times can be programmed independently. The decision system is based on driving conditions, used to maximize performance or minimize fuel consumption and emissions. This allows a greater degree of control over the engine which in turn provides significant performance benefits. This article presents reviews of camshaftless technology developed by VALEO. It is a system that uses solenoid valves to open and close the valve. The solenoid valve will be mounted right on top of the valve inside the engine. The author can see that the technology using this electronic control valve will help reduce the fuel consumption of the engine.

Camshaftless Technology on Internal Engines

Along with the development of internal combustion engines, camshafts have also been developed to optimize engine performance. In all types of internal combustion engines, the crankshaft is connected to the camshaft via a toothed belt, chain or pinion. When the crankshaft turns, the camshaft spins and opens and closes the intake and exhaust valve respectively. However, in this non-camshaft engine technology, each intake and exhaust valve will be integrated with an electronically controlled hydraulic pump unit. This system provides a unique ability to independently control intake and exhaust valves. For any engine load, load and discharge times can be programmed independently. The decision system is based on driving conditions, used to maximize performance or minimize fuel consumption and emissions. This allows a greater degree of control over the engine which in turn provides significant performance benefits. This article presents reviews of camshaftless technology developed by VALEO. It is a system that uses solenoid valves to open and close the valve. The solenoid valve will be mounted right on top of the valve inside the engine. The author can see that the technology using this electronic control valve will help reduce the fuel consumption of the engine.

Thermal analysis on different exhaust valve materials of compression ignition engine

Thermal load due to non-uniform temperature variations is one of the reasons for premature exhaust valve damage. Thermal analysis helps in estimating the heat flow accurately so that temperature distribution can be lowered / optimized to prevent failures due to excessive stresses. Therefore, the focus of this study is to perform thermal analysis on the compression engine exhaust valve at steady state condition. The investigations are carried out using ANSYS. Three different materials, namely aluminum nitride, stainless steel, and silicon nitride are chosen. Silicon nitride materials is found to be the right material for engine exhaust valve on the basis of material mechanical properties and thermal distribution related thermal stress induced on the exhaust valve.

Optimization of process parameters on engine exhaust valves using Taguchi method in friction welding process

There are many parameters which are used to process and execute the effective way of welding technique. The friction force, upset force and soft forces are the parameters which are considered during the welding process. In this study, friction welding has been taken to join the engine valve’s stem (SUH11 steel) and head (21–4 N grade steel). The application of pressure is the primary factor followed by the time which plays a vital role in any kind of processes. The welding length should be known before starting the friction welding process. From these materials Bi metal poppet exhaust valves are machined and with the machining parameters the material has been optimized. Design of experiments is applied in this study and the controlling elements are identified by the effective tool of Taguchi Method. By selecting the parameters L8 Orthogonal Array is fixed for this work. Further, the multiple linear regression analysis is taken up and it is followed by ANOVA which has been implemented for the entire length of the welding. In order to optimize the work, MINITAB 18.1 software is used.

Feature extraction of non-linearity and low noise-signal ratio signals and its application to engine fault diagnosis

Since the vibration signals of engine cylinder head come from different interference sources, it is difficult to detect weak but useful signals in the background of noise. Aiming at nonlinear and low noise characteristics of engine vibration signals, a method based on integrated empirical mode decomposition (EMD) and fractal dimension is proposed. Firstly, the integrated EMD method is used to decompose the nonlinear low noise signal into a set of intrinsic mode functions from high to low. Then the morphological fractal dimension is applied to the intrinsic mode function (IMFs). The fractal dimension of the characteristic IMF is calculated. The vibration signals of a diesel engine exhaust valve under normal and leakage conditions are analysed. The results show that this method can extract fault features of diesel engine exhaust valve.

Simulation of Composite Titanium Nitrite (TiN) Coated Internal Combustion Engine Exhaust Valve using ANSYS

In Internal Combustion Engine, valves play a crucial role in the circulation of intake and exhaust gases. Although inlet valve is exposed to higher temperatures during combustion, its failure rate is less when compared with exhaust valve. This is because the inlet valve is cooled by fresh charge admitting into the cylinder. But exhaust valve is heated up by the enormous heat carrying flue gases. Hence it is more prone to failure and has become the focus of study. The exhaust valve undergoes mechanical and thermal loads when gases are circulated from the cylinder. The valve is exposed to these extreme high temperatures subjected to fatigue loads which cause failure of valve. The valves should possess good material properties at high temperatures i.e., higher hardness, hot hardness, higher thermal conductivities and high strength properties. It has been observed that the exhaust valve performance can be appreciably enhanced by using thin film Titanium coatings like Titanium Nitride (TiN), Titanium Carbide (TiC), Titanium Nitride (TiCN) based Titanium coatings. The Titanium based thin film coatings have high corrosion resistance, less wear rates due to cyclic loads, and higher thermal resistance. In the present work, the valve coated with TiN and uncoated IC engine exhaust valves, here poppet valve of four stroke two wheeler engine valve is chosen and simulated under both high temperature loads and mechanical loads using finite element analysis(FEA). The simulated results obtained are then compared for both coated TiN and uncoated valve. It indicates that the Titanium Nitrate (TiN) coated valve has low thermal resistance and less thermal and mechanical failure than uncoated valve. FEA simulated results of TiN coating on the valve and uncoated exhaust valves are analyzed and presented in the research article.