Valve Guide Research Articles

Novel study on investigating the mechanical, microstructure morphological, and dry sliding wear characteristics of grey cast iron GG25 with copper additions for valve guides in internal combustion engine

Introduction: The performance functionality efficacy of the engine’s valve train assembly is considerably affected by the valve guide. Material selection is impacted by the prolonged operational lifespan of engines, which favours casting and machining materials such as cast iron. The intent of this study is to examine the dry sliding characteristics of GG25 cast iron with copper additives. Discovering the ways in which variations in load and sliding velocity impact wear characteristics is of paramount significance.Methods: The research entailed the examination of wear characteristics across various environmental conditions. Loads were varied at 30 N, 40 N, and 50 N while maintaining a 1 m/s velocity constant. In the same manner, sliding velocities of 0.5 m/s, 1 m/s, and 2 m/s were varied while a constant load of 30 N was maintained. Experimental techniques were carried out at ambient temperature. Throughout the investigations, frictional forces and the coefficient of friction were also determined. The wear mechanisms of samples that had become deteriorated or worn-out were examined by employing a scanning electron microscope when combined with EDX analysis.Results: A rise in the normal load from 30 N to 40 N led to a twofold rise in wear losses, measuring 417 microns as compared with 222 microns previously. The range of wear losses observed at moderate speeds (0.5 m/s–1 m/s) was 133–222 microns. Conversely, the maximum wear loss observed was 1,226 microns at elevated sliding velocities of 2 m/s, in contrast to 617 microns at higher normal loads of 50 N. Additionally, the research discovered that normal load is more pronounced when both loading and speed are moderate, whereas sliding speed becomes more substantial when both are raised, culminating to higher wear losses.Discussions: In summary, the research highlights the considerable effect that normal load and sliding speed have on the prevalence of wear losses. In conditions of moderate loading and velocity, the influence of normal load is more significant. However, as sliding accelerates, it becomes the predominant factor. An analysis of frictional forces as well as the coefficient of friction indicated that under loading conditions of 30 N–50 N, the friction coefficient raised from 0.238 to 0.43. The wear mechanisms, as discerned via scanning electron microscopy and EDX analysis, underscored the considerable impact of increased sliding velocity on wear loss in comparison to conditions of higher loading.

Heat - and Wear-Resistant Nanocomposite Material Based on Copper Powder for Valve Guides of High-Forced Engines

The article presents the results of the development of heat - and wear-resistant nanocomposite material based on copper powder Cu-Al-C-O system, which due to the optimally selected chemical composition and dispersion-strengthened structure with a strengthening phase γ-Al2O3 of nanodispersed range has a set of physical, mechanical and operational characteristics, at its level significantly higher than the similar characteristics of the standard bronze CuNi2Si F65 DIN 17666, used by a number of engine companies for the valve guides of powerful and high-forced internal combustion engines. In particular, the wear resistance coefficient for the valve guide made of this material is 17 times higher than for the guide made of this standard bronze. In this case, the coefficient of score-resistance of the bushings of the new material is 2.54 times higher than the same index for the bushings of bronze. Moreover, it also provides the least wear not only of the guide bushing but also of the valve, i.e. of the entire pairing as a whole.

Analysis of operating conditions of heavy-loaded and heat-stressed friction units of powerful internal combustion engines and development of copper nanocomposite powder materials for them

The article provides analysis of operating conditions for the «valve – valve guide» heavy-loaded and heat-stressed friction unit of the gas distribution mechanism of powerful internal combustion engines and establishes requirements to materials for valve guides. It describes nanoc omposite materials based on copper powder with aluminum, carbon, iron and oxygen additives developed by the authors of the present article. The reactionary mechanical alloying method and powder metallurgy technologies in use made it possible to develop materials having a dispersion-strengthened structure with nano-disperse level sizes of structural components (dispersoids, subgrains). They have a recrystallization temperature of over 950оС, good therm-conductivity, a low linear thermal expansion coefficient and excellent tribotechnical properties. For example, a copper nanocomposite material containing 0.9 wt % aluminum, 0.3 wt % carbon, 0.4 wt % iron and 0.017 wt % oxygen, by its tribotechnical properties, greatly surpasses CuNi2Si (F65 DIN 17666) bronze widely used by many leading engine-making companies for production of valve guides. By their properties, the developed materials meet requirements that have to be imposed on modern and promising materials for valve guides of powerful internal combustion engines.

Simulation of Multi-Stage Fine Machining Processes at the Example of Valve Guide and Valve Seat

Fine machining processes are of great importance in automotive series production, e.g. the machining of valve guide and seat in the cylinder head of a combustion engine. In industrial manufacturing processes, disturbances are inevitable and provide a measure of uncertainty in each production step. Increasingly, the influence of such uncertainties is being evaluated using simulation models. In this paper, a modeling approach for simulation of multi-stage fine machining processes with step tools is presented and investigations regarding influence of uncertainty caused by disturbances are performed.

Design of Epoxy based Resin Composites for Automotive Applications: A Case Study on IC Engine Valve Guide

The present attempt in this project is to reduce the vibrations, temperature due to friction, noise and weight of I C engine valve guide by replacing conventional metal valve guide with composite valve guide. Composite materials have been used in automotive components because of their properties such as low weight, high specific stiffness, corrosion resistance, ability to produce complex shapes, high specific strength and good impact energy absorption etc. The Internal combustion engine valve guides are the parts that support the valves in the cylinder head, besides this it keeps lubricating oil from getting sucked into the combustion chamber past the intake valve stem, it keeps exhaust gases from getting into the crankcase past the exhaust valve stem and it also keeps the valve face in perfect alignment with the valve seat. A valve guide test rig is indigenously fabricated. Valve guides are manufactured using the developed composite material (Resin ARL-136, Hardener AH-126 and 4 vol% WS2), on a CNC lathe. The performance of the developed composite guide under varied conditions of speeds, that is, fixed change in rpm and modulated changes in rpm is assessed. Noise, temperature and vibrations are measured. The experimental data revealed that contribution of composite guide in respect of acceleration, velocity and displacement components of vibration is not substantial. A substantial reduction in noise levels is seen. As far as temperature rise due to friction is concerned maximum components fail at elevated temperatures, with composite guides the temperature generated due to friction at higher speeds is less, a considerable weight reduction is also observed.

Comparative Study of Different Materials with Al-Sic for Engine Valve Guide by Using FEM

In this work, an effort has been designed to raise the reliability of engine using Al-Sic composites with other alternatively materials for the engine valve guides. Aluminum matrix composites have found the most suitable inside automotive, aerospace and aircraft industries and contain the greatest promise for future year’s growth. The finite element analysis of the Al-Sic composite with Titanium alloy (Ti-834), Copper Nickel Silicon alloys (CuNi3Si), and aluminum bronze alloy as an alternative material for engine valve guide was done using Ansys 13.0 software. The stress analysis of engine valve guide under the different pressure and temperature is considered, the pressure is taken as from 10 MPa to 100 MPa with different temperatures varying from 600℃ to 650℃. The temperature, principal stress and principal strain distribution on the entire surface area of the engine valve guide were obtained. The stresses were observed to be well below the permitted stress for all the materials but the Al-Sic composites found the most suitable one. Valve guide is modeled in pro-engineer software and analysis is carried out in Ansys 13.0. The deformations and stresses induced due to structural and thermal loading is illustrated and discussed.

Comparative Study of Different with al- sic for Engine Valve Gu ide by using FEM

In this Work an effort has been designed to raise the reliability of engine using Al-Sic composites with other alternatively materials for the engine valve guides. Aluminum matrix composites have found the most suitable inside automotive, aerospace and aircraft industries and contain the greatest promise for future year’s growth. The finite element analysis of the Al-Sic composite with Titanium alloy (Ti-834), Copper Nickel Silicon alloys (CuNi3Si), and aluminum bronze alloy as an alternative material for engine valve guide was done using Ansys 13.0 software. The stress analysis of engine valve guide under the different pressure and temperature is considered, the pressure is taken as from 10 MPa to 100 MPa with Different temperatures varying from 600 °C to 650 °C. The temperature, principal stress and principal strain distribution on the entire surface area of the engine valve guide were obtained. The stresses were observed to be well below the permitted stress for all the materials but the Al-Sic composites found the most suitable one. Valve guide is modeled in pro-engineer software and analysis is carried out in Ansys 13.0. The deformations and stresses induced due to structural and thermal loading is illustrated and discussed.

Impact of optimising fluoroscopic implant angles on paravalvular regurgitation in transcatheter aortic valve replacements – utility of three-dimensional rotational angiography

The clinical value of optimising implant angles during transcatheter aortic valve replacements (TAVR) remains undefined. The Aortic Valve Guide (AVG) is a proprietary software that provides structured analysis of three-dimensional images from rotational angiography (DynaCT). This study compares AVG with preprocedural multislice computed tomography (MSCT) and DynaCT in optimal implant angle prediction for TAVR, and evaluates if an optimised implant angle is associated with reduced paravalvular regurgitation (PVR). One hundred and six consecutive patients were included, comprising three groups. Group 1 (n=19) underwent no preprocedural MSCT or DynaCT (or AVG); Group 2 (n=44) underwent periprocedural DynaCT, without AVG; Group 3 (n=43) had DynaCT with AVG. Implant angles yielded were graded as excellent, satisfactory or poor. Group 3 were more likely than Groups 2 and 1 to have excellent implant angles (83.7% vs. 52.3% vs. 42.1%, respectively, p=0.001). In 100 patients who had 30-day transthoracic echocardiogram follow-up, an excellent implant angle was significantly more likely to be associated with no PVR than a non-excellent angle (41.3% vs. 21.6%, respectively, p=0.045), independent of operator experience and THV used. Optimising implant angles may be important in reducing PVR. This is significantly more likely to be achieved with AVG rotational angiography.

A Measuring Method of Circular Run-Out in any Direction of Valve Seat Related to the Centerline of the Valve Guide

The difficulty of measuring the run-out of engine valve seat related to the centerline of the valve guide is the determination of the datum axis. A method that the gauge was fixed on the conical surface of the valve seat was chosen. One sensor on the conical surface of the gauge measures the run-out of the valve seat related to the centerline of the gauge. Another two sensors of the gauge measures the centerline of the valve guide. The mathematic model of measurement is established, the run-out of the valve seat related to the centerline of the valve guide can be archived.

The Clinical Utility of Dyna CT and Aortic Valve Guide Software in TAVR—The Prince Charles Registry

The Clinical Utility of Dyna CT and Aortic Valve Guide Software in TAVR—The Prince Charles Registry

Aortic Valve Guide—Automatic Valve Annulus Profiling For TAVI. First Australian Experience

Background: Both ‘Corevalve’ and the ‘Edwards’ valves require the prosthesis to be accurately placed in the proximal ascending aorta. The valve must be profiled perfectly perpendicular to the X-ray beam before deployment. Performing an on-table CT scan (Cardiac Dyna CT) has been shown to effectively demonstrate the correct C-arm angle for placement of the valve in over 95% of cases but requires some post processing/image rendering. The new Aortic Valve Guide Software (AVG) (Siemens Medical Enlargen) is designed to automatically profile the valve annulus and demonstrate the ideal C-arm angle in which to deploy the valve automatically. This proof of concept study assessed the effectiveness of AVG. Method: Seven patients who were selected for TAVI (three trans-apical and three trans-femoral Edwards valve 1 Corevalve) had on table Cardiac Dyna CT performed prior to Valve implantation. The AVG software was utilised to predict the ideal C-arm angulation in which to profile the valve annulus. The predicted angulation was confirmed with an aortogram. Results: The AVG software automatically predicted the correct angulation in all seven procedures (100%). Conclusion: AVG accurately automatically profiles the aortic valve annulus and demonstrates the ideal C-arm angle in which to deploy the Valve.

Fabrication and testing of Al–SiCp composite poppet valve guides

Composite materials are replacing the materials used in various fields and are the candidate materials for future growth. Metal matrix composites are the class of composite materials finding vast applications in automotive, aircraft, defense, sports, and appliance industries. In the present work, Al–SiCp composites with 5–30 wt.% of SiC particulates were fabricated using powder metallurgy as well as casting processes. Mechanical alloying of aluminum and SiC particles was done prior to compaction so as to enhance the properties of the fabricated powder metal components. A custom built sliding valve guide wear test rig was fabricated to simulate the valve stem/guide wear under cold start condition of an engine by reciprocation of a valve stem under different imposed loads, against a stationary poppet valve guide. The hardness and radial crushing load was measured for the Al–SiCp composite poppet valve guides and were found better than the cast iron poppet valve guides presently used in engines. The wear test of the poppet valve guides was done using valve guide wear test rig, which revealed that the Al-20 wt.% SiCp and Al-30 wt.% SiCp composite poppet valve guides have higher wear resistance than the cast iron poppet valve guides. The hardness, radial crushing load, and wear resistance of Al–SiCp composite poppet valve guides were found to increase with increase in weight percent of SiCp. The microstructural analysis of the cast and PM Al–SiCp composites was also done using scanning electron microscope. Finite element analysis of the Al–SiCp composite poppet valve guide was also done using Ansys software, which supports the successful implementation of the Al–SiCp composite poppet valve guides for automobiles.

Reciprocating friction and wear behavior of a ceramic-matrix graphite composite for possible use in diesel engine valve guides

Reciprocating ball-on-flat tests were conducted on prepared sections cut from cast iron, silicon nitride, and silicon nitride/12.5 vol% graphite composite valve guides over a range of temperatures, normal loads, speeds, and lubrication conditions. The purpose of this work was to ascertain whether the latter ceramic composite would produce a beneficial lubricating film on the opposing surface and serve as a self-lubricating material. Type 440C stainless steel was used as the counterface material. Machining practices were selected to provide the surface roughness and lay (direction of grinding marks) similar to that of actual valve guide bores. For comparison with the ceramic composite material, both cast iron and silicon nitride matrix materials were also tested. Tests were also performed using graphite powder on the silicon nitride matrix material to ascertain what frictional behavior might be observed in the most favorable case. Friction and wear data, combined with surface chemical analysis confirmed that the current composite, while wear resistant, did not provide any lubrication advantages over silicon nitride itself. No evidence for the sliding-induced formation of a beneficial graphite film was obtained by optical examination, scanning electron microscopy, or surface chemical analysis. While the type of graphite used in the present composite fractured into fine particles and did not form a lubricating film in our experiments, the results do not preclude the possibility of developing other ceramic composites with self-lubricating properties.

Optimum sintering conditions for bushings of automobile engine valve guides and the effect of some factors on their physicomechanical properties and structure

1. The optimum conditions for sintering 8.0–8.5-kg boat loads of valve guide bushings may be taken to be a temperature of 1160°C and a boat pushing period of 20 min. 2. Carbon segregation along the bushing height leads to instability of strength properties. 3. The material of bushings from PZh2M2 powders surpasses in physicomechanical properties that of bushings from PZh2M3 powders. 4. Nonuniform compaction, resulting in increased porosity in the central part, has an adverse effect on the strength properties of bushings, even when the latter's over-all porosity is of the order of 20% (which meets the requirements of TU 02-69 specification for valve guide bushings). When one-fifth or two-fifths of a bushing at either end has a higher porosity, the strength of the bushing remains unchanged. 5. In an investigation of the temperature distribution in an OB-357 furnace during the sintering of bushings, it was established that, when the operation is performed with a 20-min period at 1160°C, sintering temperature is maintained over three boat lengths, which ensures an optimum sintering time, 1 h, and imparts satisfactory strength to bushings. 6. A study was made of the dimensional changes of bushings from PZh2M2 and PZh2M3 powders under various sintering conditions. A knowledge of these changes is indispensable in die calculations if parts of the required degree of dimensional accuracy are to be produced.

Report of the Late Automobile Research Committee of the I.A.E. (Now the Motor Industry Research Association) on the Effect of Operating Variables on Temperatures of the Exhaust Valve, Valve Guide and Valve Seat

Report of the Late Automobile Research Committee of the I.A.E. (Now the Motor Industry Research Association) on the Effect of Operating Variables on Temperatures of the Exhaust Valve, Valve Guide and Valve Seat