Search

This study is dedicated to the development of the copper dispersion-strengthened composite material with increased indexes of heat - and wear - resistance for heavy duty friction pairs parts and, first of all, for valve guides of high-forced internal combustion engine and plunger of the die-casting machine. As a result of the research conducted, the material was obtained containing (% wt): aluminum − 2.90; carbon − 1.20; oxygen − 0.20; copper - the rest. The developed material has the recrystallization temperature of 1000 °C and exhibits higher tribotechnical properties compared to the standard materials, in particular, compared to bronze CuA19Fe3. The tests conducted revealed that the developed dispersion-strengthened copper-based material has recrystallization temperature almost two times higher than that of CuA19Fe3 bronze, and the wear out intensity is almost four orders of magnitude lower, which ultimately provides parts made of new material a significantly higher life-time compared to the parts life-time from standard bronze.

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.

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.

The increasingly strict emission regulations in combustion engines are raising high requirements for the engine valve train system. In this paper, a novel multifunctional wear apparatus is designed to study the performance of engine valve train components. The apparatus employs a mechanical loading system, which consists of a special eccentric wheel and disc springs that apply the combustion loads, and the contact configurations and loading conditions of valve train components are simulated. It has three test functions for different components through specifically designed fixtures. The first function aims to evaluate the interaction between the valve seating face and the seat insert at high temperatures and loads. The second function is used to study the friction and wear properties of the valve stem and the valve guide. The third function is designed to evaluate the performance of the valve seals. At last, a verification test was carried out by the proposed experimental method. A pair of new exhaust valve and seat insert is tested for the performance evaluation of the first function. The wear mechanisms acting on the pairs interface are shown to be a combination of oxidative wear, adhesive wear, as well as fatigue flaking.

The paper describes a completely new approach to fully variable valve actuation (FVVA), which allows almost unlimited continuously variable control of intake and exhaust valve opening and closing events, and duration without the use of a camshaft. DigitalAir replaces conventional poppet valves with horizontally actuated valves located directly above the combustion deck of the cylinder head, which open and close a number of slots connecting the cylinder with the intake and exhaust ports, Figure 1. The stroke of the valves to provide the full flow area is approximately 25% of the stroke of the equivalent poppet valve, thus allowing direct electrical actuation with very low power consumption. This design arrangement also avoids the risk of poppet valve to piston collision, or the need for cut-outs in the piston crown, since the valves do not open into the cylinder. The paper will present analytical and experimental data which confirms that the proposed FVVA system can meet the basic performance requirements of modern GDI engines with respect to breathing characteristics across the speed range, throttleless operation at and above idle, opening and closing event optimization, cylinder deactivation, control of residual gas fraction / scavenging and exhaust thermal management. Analytical results were developed using GT-POWER Cycle Simulation and CONVERGE computational fluid dynamics (CFD). Cycle simulation was used to study the system level performance, such as full load capability and transient response, and in particular to quantify the fuel consumption benefits of throttleless operation. CFD was used to better understand the opportunities for in-cylinder charge motion - tumble, swirl and turbulence. JP SCOPE Inc. has been running experimental engines with DigitalAir for several years and has successfully completed performance and durability tests. The mechanical and thermal design of the cylinder head, and the design of the actuator will be covered in Part 1 of this paper [1].

This article presents the experimental study of the pneumatic valve's dynamic loading. The influence of structural and technological factors on the stress state of the sealing elements and their tightness are estimated.

To address the problem of a piston-valve collision associated with poppet valve engines, we replaced the conventional poppet valve with a solenoid operated stepping valve whose motion is perpendicular to that of the piston. The valve events are software controlled, giving rise to precise intake/exhaust cycles and improved engine efficiency. Other rotary engine models like the Coates engine suffer from sealing problems and possible valve seizure resulting from excessive frictional forces between valve and seat. The proposed valve on the other hand, is located within the combustion chamber so that the cylinder pressure help seal the valve. To minimize friction, the valve clears its seat before stepping into its next position. The proposed system was successfully simulated using ALTERA's QUARTUS II Development System. A successful prototype was built using a single piston engine. This is an ongoing project to eventually produce a 4-cylinder engine.

In the present study, a zero-dimensional numerical method is developed based upon the crank angle to investigate reciprocating natural gas compressor with valve faults. This model aims to take piston movement, valve dynamic, and mass flow rate through valve and orifice equations into account. To this end, three control volumes including compressor cylinder, suction, and discharge chambers with equivalent mass and energy equations are investigated. Valve faults, which include valve plate failure, wearing on the plate and its seat, and springs deterioration, lead to valve leakage. For valve leakage simulation, a hole in the valve plate is considered. Simulated results validate the previous experimental results for normal operating compressor with healthy valves. The predicted results show that the suction and discharge valve failures decrease compressor mass flow rate and increase discharge gas temperature. Furthermore, effect of the suction valve fault is more serious than that of the discharge valve fault. In addition, valve fault can be detected by monitoring the gas temperature of the suction and discharge chambers.

In this work the failure analysis of the exhaust valve of diesel engine was performed. Visual examination of damaged engine parts showed that on the fracture of exhaust valve the beach marks, typical for fatigue failure were observed. Additional observations of the crack initiation zones indicated that the crack origins were not covered by material defects or corrosion products. In order to explain the reason of premature valve damage, the non-linear finite element analysis was utilized. The discrete model of simplified valve system composed of the valve guide, the poppet valve and the seat face was defined. In numerical analysis both the mechanical force arising from the valve spring and also the thermal load resulting from the non-uniform temperature field were defined. The results of nonlinear static analysis showed that in the engine without any disturbances, the maximum principal stresses in the critical zone of the valve have low values. The examination of another (non-defected) valve from damaged engine head indicated that irregular carbon deposit was located on the valve face. The results of stress analysis performed for the valve with the carbon deposit showed, that in the valve stem a high bending stresses were occurred.

In this paper, the valves for a LPG gas cylinder have been investigated on the body height and weight by comparing design data between typical automatic shut-off vertical and newly developed horizontal valves. The height of an automatic shut-off horizontal valve is radically reduced by 41~42% compared with that of a typical automatic shut-off vertical valve. And, the body weight of a horizontal valve is also reduced by 29~40% compared with that of a vertical shut-off valve. This result is just achieved by a structural design modification from typical vertical valve to horizontal arrangement of various valve components.

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.

A butterfly valve is a type of control valve which is used for isolating or diverting the flow. The working mechanism takes place from the disc. Function is similar to that of a ball valve, which allows for quick close and open systems. Butterfly valves are selected because of their lower cost to other valves manufacturing techniques, also lighter in weight, meaning less support is required. Rotating disc is placed in the center of the valve body. Disc can be operated by either manual handle or electrical actuators of various torques. The close-off pressure acting on the disc is directly proportional to the in-line pressure in pipe. The valve is selected according to the pressure and torque and pipe diameter, which allows lowering the damage the valve in operation. Fluid flow is controlled through piping systems, which in turn are connected to the valves. The valve body comprises of disc, which also controls the flow of fluid through various angles of opening. The disc is connected in Centre through the stem which is connected to either handle or the rotating actuator. The design of the valve body and disc is of much important for linear or equal percentage flow. Nowadays the equal percentage flow is obtained by characterizing disc, which allows to maintain the equal percentage flow at different differential pressure across the pipe. Sometimes it becomes very critical to maintain the equal percentage flow; CFD can predict the flow performance and rate of discharge through the valve. This paper focuses on the study of 8”and 20” valves performance factors and results obtained by analysis as well as from the load bearing capacity of the valve However special thanks to Prof. Yogesh Dodia for his guidance to make this paper rational and justifiable.

In production processes uncertainty has a great impact on the product quality as well as production costs. In automotive industry the reaming of valve guides in a cylinder head of a combustion engine is a quality determining process. Due to the force fitting of the valve guides into the cylinder head the final reaming process has to deal with increased uncertainty. On the other hand, the finished hole is closely tolerated. To ensure the process reliability the admissible tolerance must be strictly met even in case of uncertainty. This paper presents a possibility to achieve process reliability by a modified process chain with an additional pilot reaming tool. Thereby, the effect of different cutting edge preparation is also analyzed. Further, the influence of the pilot reamer geometry on the final hole quality is investigated.

For studying the kinetic characteristics of passive shuttle check valve at the moment that it closes its valve core on the condition of high pressure differences, this paper first constructs the equation of motion of the valve core and two- dimensional geometrical model by using computation fluid dynamics method, then with the help of the calculation method and physical model provided by Fluent software, employing the dynamic mesh and user-defined functions, simulates the unsteady flow in the valve core's closing process under the different pressure fluctuations, and obtains the stress nephogram, the velocity vector diagram, the speed curve, and pressure curve of the interior flow field of the valve. The results show that the bigger the value of valve fluctuation is, the larger the fluid pressure that the valve core is subjected to, the openness of the core and the speed fluctuation of the core are, and that in the case of sudden decompression at the entrance, the core can be shut down quickly with the steady speed field and pressure field. The simulation results are conducive to the design and optimization of structure parameter of shuttle check valve. The shuttle check valve invented by Zeng Xiangwei can automatically open and close itself under the control of the energy of the pipeline system, needing no extra power or control. The shuttle check valve can be closed safely and quickly in a relatively small back pressure due to its reasonable structure (1), and it now has been used in tens of large chemical plants and oil plants in China. In recent years, many researchers have been studying the shuttle check valve (2-6). Li Liangchao (7) finished the numerical simulation of the opening process of shuttle valves; Chen Kun (8) analyzed the characteristic of the water attack in the shuttle valve pipe system; RenYuxin (9) simulated the noise-reduction feature of the shuttle valve. Yet few studies on the valve score's activity during the closing process of shuttle valve under the fluctuant pressure have come out. Simulation of the valve has been developed from the steady simulation at a certain opening degree to the non-steady simulation under a certain motion law. Therefore, it is necessary to study the impact of the pressure differences between the inlet and the outlet upon the closing process of the valve. The paper simulates the motion of the valve clack during the valve closing; provides the reference to the design of the structure parameter of the shuttle check valve and optimization. 2. STRUCTURE OF SHUTTLE CHECK VALVE The structure of shuttle check valve is shown in Fig. (1). The outside is the valve body and the inside is the spool, and a spring is placed in the rear of valve spool for pre- tightening. When medium flows into the left side of the picture, and the fluid's pressure on the spool is larger than the pressure of the spring and fluid from the right on the spool, the valve will move towards the right, and consequently valve is opened and the fluid will flow from the left to the right. When the pressure of the fluid from the left is less than the pressure of the fluid from the right and the spring's acting force, the spool will move to the left and consequently the valve is closed and backflow is prevented. Because the closing results from the spring's force and the pressure differences of both sides, therefore, the shuttle check valve can act as non-return function even in the case of the lowest backpressure (10). Functionally speaking, the shuttle check valve can function as opening and closing, throttling, damping, and amplify regulator and controller.

When designing the servo valve with different structure parameters, the influence of the interaction between the liquid and the solid on the performance of servo valve can only be obtain by the method of experiment, and then it can increase the time and cost of designing the servo valve. The liquid-solid couple method can obtain the influence of structure parameters on the performance of servo valve under the circumstance of reducing the experimental cost and time. The paper chooses the servo valve of A and B as models for study, The text adopts FSI method to analyze the flow field of double nozzle baffle electro-hydraulic servo valve prestage through the software of ANSYS, research the change of the prestage flow field by deflection of loaded armature baffle components, contrast and analyze the change of velocity, pressure, power loss and flow coefficient of fixed choke, nozzle, return port, and the displacement of the valve core of slide valve, stress of armature baffle components, pressure at both ends of spool. Summarize the advantages and disadvantages of A and B servo valve, and find different parameters of servo valve have different performance, it is difficult to find a common structure and size. It can help us to select the requirement structure by using fluid-structure interaction, reduce experiments and save cost.

The main rejections in the machining sections are exhaust valve port leak, injector bore blow hole, induction passage punchered, inlet valve port leak, top face unwash, valve guide hole blow hole, top face leak, joint face unwash, induction face unwash, rear face unwash, valve port unwash, water mixing with oil., water passage blocked, emf leak, injector bore leak, inlet valve port blocked, water way leak, oil way leak and defective jig location pad. This paper describes the method by which the rejections while maching the cylinder head, is minimized.

This is part two of the paper on conceptual design of an engine valve. The previous paper describes the background and the need of an engine valve for an internal combustion engine. The present state of the engine valve technology and the innovations incorporated in its design has been described. This paper presents the conceptualization of an innovative valve train aiming at lesser number of components, reduction in friction and wear, proper sealing, and trimming down pumping losses. Various geometric designs of valve trains have been detailed and compared. Finally a convolution based poppet valve mechanism, which is free from numerous mechanical elements like camshaft, cam, push rod, rocker arm and rocker bearing has been recommended. Finite element analysis of convoluted spring has been carried out to ascertain safe limits in terms of stresses and achieving desirable valve lift. Magnetorheological fluid and electromagnet are used to vary the valve-lift.

The large flow electro-hydraulic directional valves are the key operating components for automation of the hydraulic roof supports in the coal mine. Cracking is a common failure mode of the valve. Effects of the buffer damp diameter, the valve type and the static pressure on the stress of the valve were researched. The valve dynamic behavior was investigated by AMESim. The transient collision stresses of the inlet valve sleeve of the main control valve under different buffer damp diam- eters and different valve types were investigated by ANSYS/LS-DYNA. The static stress analysis was conducted in ANSYS too. Results show that the valve failure is due to the fatigue of the inlet valve sleeve when suffered from the collision stress wave in the valve opening process, rather than the lack of component strength. The buffer damp diameter, the key parameter of the valve, has a significant effect on the collision stress of the inlet valve sleeve. The integrated type valve has a better stress state compared to the separated type valve. This paper provides an effective method to solve the fracture problems of hydraulic directional valves. It is also significant for the design and optimization of hydraulic components.

Four types of exhaust valve models are established, the lightweight on engine exhaust valve is designed. The results on thermal mechanical coupled analysis of four exhaust valve models show that: The maximum values of mises stress appear in contact surface between the valve cone and valve seat; Comparing the maximum mises stress, as wall thickness of the hollow valve increases, there are gradual decrease trends in the same positions of the valve cone, the locking groove, neck and end face of the valve disc. The research on the stress distribution of exhaust valves and the variation law between hollow valves′s strength and their wall thickness provide a good reference for improvement in the future.

Modern automotive engines almost exclusively operate on the 4-stroke Otto cycle and utilize poppet valves for gas exchange. This state of affairs has not always been the case, however, and one unusual and relatively successful technology that was once in mass production (albeit in piston aero engines) was the Burt-McCollum single sleeve valve. This paper investigates the timing and angle-area of a Bristol Centaurus engine cylinder, which utilized such a single sleeve valve for gas exchange, using some modern tools. A comparison with poppet valve angle-areas is made. Finally, the results are also used to study the potential of variable valve timing and the interaction with variable compression ratio of a single sleeve mechanism. An opportunity for the sleeve valve is provided by the fact that direct injector placement in the cylinder junk head is effectively completely free, and furthermore multiple ignition sites can be incorporated to increase the delivered ignition energy for dilute mixtures, for example. Furthermore, as there are no mechanical impact loads (as arise from poppet valves hitting their seats, for instance), theoretically ceramics or temperature-swing materials could be more simply applied when using the technology as well, and over a larger proportion of the total combustion chamber surface area than is possible with poppet valves. The motivation for studying the interaction of timing and compression ratio was driven by the observation that it would be relatively simple to incorporate a wide-range continuously-variable compression ratio mechanism without the spatial limitations enforced by the presence of poppet valves and their timing and drive mechanisms in the cylinder head of a conventional 4-stroke engine. The potential range of compression ratio variation is also significantly larger than for poppet-valve engines because the piston does not have to incorporate valve pockets for valve-to-piston clearance at high compression ratio settings. As a result the surface-area-to-volume ratio of the combustion chamber would be expected to be less effected over any given ratio range as well. The results of this study show a very favourable trade-off between port timing, compression and expansion ratios with a simple variable compression ratio mechanism being employed. Furthermore, the system is found to provide a large potential to yield increased Miller cycle operation automatically.

Se determinaron la dureza, pérdida de masa y coeficiente de fricción, de guías de válvulas para motores de combustión interna fabricadas en latón por proceso de pulvimetalurgia, con el objetivo de conocer si cumplen con las exigencias que requiere un motor de combustión interna, utilizando como parámetro comparativo guías de válvulas comerciales de latón producidas por fundición. Se estudió, si las propiedades son homogéneas a lo largo de toda la guía de la válvula y se evaluó el proceso de reprensado que se lleva a cabo de manera adicional en la línea de producción. Se determinaron las durezas Brinell y Vickers; el coeficiente de fricción y la tasa de desgaste (ensayo pin on disk). Mediante microscopía electrónica de barrido y análisis metalográfico, se estudió el mecanismo de desgaste. Se llevó a cabo la determinación de la composición química de las guías y el efecto del reprensado cuantificando la porosidad superficial, mediante el software Analizador de imágenes Pro Plus®. Se puso de manifiesto que las piezas fabricadas por proceso de pulvimetalurgia presentaron valores inferiores en sus propiedades mecánico-tribológicas en comparación con las guías de válvula comerciales. Estos resultados permitirán mejorar las condiciones de fabricación de las guías mediante pulvimetalurgia.

The simulation process being conducted to determine the air flow effect between the original exhaust system and modified exhaust system. The simulations are conducted to investigate the flow distribution of exhaust gases that will affect the performance of the engine. The back flow pressure in the original exhaust system is predicted toward this simulation. The design modification to the exhaust port, exhaust pipe, and exhaust muffler has been done during this simulation to reduce the back flow effect. The new designs are introduced by enlarging the diameter of the exhaust port, enlarge the diameter of the exhaust pipe and created new design for the exhaust muffler. Based on the result obtained, there the pulsating flow form at the original exhaust port that will increase the velocity and resulting the back pressure occur. The result for new design of exhaust port, the velocity is lower at the valve guide in the exhaust port. New design muffler shows that the streamline of the exhaust flow move smoothly compare to the original muffler. It is proved by using the modification exhaust system, the back pressure are reduced and the engine performance can be improve.

For the reality of the variable pressure in the oil field, an adjustable disk choke valve is introduced in this paper. The structure and working performance of the valve is described in detail, too. The field application of the valve shows that the valve has such advantages as simple structure, quickly facilitate, easy installation and cleaning, long service life, safe and reliable, all these leads to the broad application prospect of the valve.

The paper deals with the load of the head of the engine. Head of SI engine, which has molded seat of intake and exhaust valve, is one of the most complex parts of the engine. It contains intake and exhaust ports, spark plugs, timing of the mechanism and channels for cooling and lubrication. Much of the final form of this component also contributes its load, which is both heat and mechanical. The biggest influence on the deformation of embedded saddles exhaust valve has a temperature distribution in the cylinder head. These temperatures are influenced by many factors, especially temperature and coolant flow, load and engine speed, which affect the combustion process and exhaust gas temperature (the engine mode is constantly changing, therefore the thermal load on the valve seats is different). In our paper we will only deal with the heat load of the cylinder head of the engine. Currently, the most common use of appropriate software tools for determining the distribution as voltage or temperature. The simulation results may not always be identical to the actual situation, so it is necessary to perform by verification. The paper described measurements of temperature on the inserted valve seats cylinder head of the engine.

Rotary valve is a device to achieve fast commutation hydraulic transmission . Rotary valve is driven by a hydraulic motor drive and can achieve rapid conversion of the hydraulic circuit . Rotary valve spool by a rotating shaft , housing , shafts and bearings and other components. Guide grooves machined on the spool shaft is evenly distributed for hydraulic cylinder into the oil and return oil conversion. The coordinate gap between the spool shaft and valve chamber bore Because will affect the leakage in the leak. How to improve the guide groove structure? We can put the guide groove by high and low partition instead of overlapping arrangement. Reducing leakage within the valve chamber and Meet with the requirements of the spool shaft and valve chamber bore.

The face of the valve seat sealing surface design, the finite element analysis and calculation of ball valve seat sealing surface and angle of the design method is studied. Through 3D CAD technology for ball valve design, guide 3D design model to finite element analysis software to calculate ,reveal the sealing load distribution of pressure in the valve seat sealing surface, sealing pressure values are obtained, through the valve seat sealing surface design Angle analysis, to obtain the optimal value of sealing surface angle.

the low pressure oil chamber and the high pressure oil chamber act directly on Both sides of the rotary valve. It will be large axial force to the valve body If the system working pressure is greater. The resulting outcome is low vibration frequency of the rotary valve driven hydraulic exciter. How to improve the hydraulic exciter frequency?We can improve the speed of the rotary valve or increase the number of rotary valve guide groove. But if we increase the tank guided number ,the diameter of the rotary valve spoo must be increased. Design a rotary valve without axial force can solve the problem of the rotary valve spool shaft size restricted. By calculation and analysis of the rotary valve spool suffered axial force . The work of a single rotary valve chamber pressure problems can be solved spool axial force

최근 자동차에 대한 환경규제가 대폭 강화되고 있으며, 배기시스템은 빼놓을 수 없는 연구과제 중 하나이다. 본 연구의 목적은 배기가변밸브의 압력 위치에 따라 최대와 최소에 대한 영향 분포를 규명하는 것이다. 실험은 배기가변밸브가 열리는 측면부에 카메라를 이용하여 실시간 각도를 확인하고 내부유량, 압력, 밸브 열림 각의 데이터를 추출하여 유동해석을 통한 배기가변밸브의 압력과 속도에 대하여 위치별 특성을 분석하였다. 압력의 결과는 밸브의 최초 열림이 머플러 내부에 압력을 감소시키는 결과를 나타내었다. 속도는 압력과 반대되는 결과를 나타내었으며, 하단부의 빠른 속도로 인한 밸브의 떨림 현상이 발생된 것으로 확인되었다. 이 연구로부터 얻은 결론은 기관성능 향상을 위해서 속도의 위치가 하단부로 유인할 경우 밸브면의 압력 분포가 더욱 증가하여 최적의 배압조건을 만들 수 있는 결과를 얻을 수 있었다. 【Environmental emission of recent automobile is drastically enhanced that it is one of the obvious assignments of exhaust system. This study is a purpose to establish of influence distribution on maxima and minima through the location of pressure on exhaust variable valve. The experiment are checked with real angles using camera which exhaust variable valve is opened side of point. Data has extracted to opening angles with internal flow, pressure. Exhaust variable valve through the floating analysis was analyzed the characteristic of location point about pressure and velocity. The pressures indicated the reduced results internal pressure within muffler. The velocity indicated an opposite results and vibration state of valve was verified to be operated as high speed from lower section. The conclusion to obtain from this study was found out the result to make the optimum back pressure condition as more increasing pressure distribution on valve face if the velocity location attracted by bottom point in order to improve for engine performance.】

The hydraulic slide valve with round orifice spool is often used in hydraulic control system. But it is prone to rotate when the hydraulic oil flow is large. The three-dimensional fluid analysis technology was used to numerically simulate the flow field in the hydraulic slide valve. By using the pressure and velocity characteristics generated for different spool structures by the CFD numerical analysis, the main reason of slide valve rotation was analyzed, which can provide basis for the optimal design of the slide valve structure.

In practice, economical reaming of precision holes requires the use of multi-blade reaming tools. The main objective of precision machining processes is to minimize any deviations arising from dimensional and shape tolerances. However, process errors such as misalignment errors between the axes of the tool and the pre-drilled hole can occur during reaming processes, thus affecting the machining outcome. This experimental study aims to investigate the influence of process errors and tool geometry on the resulting hole quality while reaming valve guides made of sintered steel alloys. There is particular emphasis on the guiding function of reaming tools with regard to varying chamfer dimensions and back taper ratios at the secondary cutting edge. The experimental results indicate that an enlarged contact zone between the secondary cutting edge and the workpiece material will lead to improved straightness tolerances.

A prototype rotary valve engine has been built from a conventional single piston generator. In this study, an e ngine c ontrol u nit, ECU, is designed, tested and implemented for the purpose of carrying out the primary engine functions of sparking, fuelling and valve events control. The rotary valve engine has no camshaft, therefore, only a crankshaft (optical) sensor is required. The controller has also the advantage of turning the engine in either direction, removing the need for a reverse gear. Full control over valve events, together with crank motion independent sparking, removes the need for a throttle valve and a mechanical starter. With the valve turning freely, no feedback sensing is necessary. The proposed ECU has been designed, successfully tested and implemented on ALTERA's UP1 prototyping board. The FPGA programmable device used is the EPM7064SLC44-5.

Recently, a certain type of aviation reciprocating engine encountered some valve sticking and valve breakage problems in succession because of lead built-up and bad compression performance of cylinders in China, which has serious impact on the safety and continuing airworthiness of this reciprocating engine and equipped aircraft. This article has undertaken an in-depth study on this valve sticking and breakage issue, analysis has been done on Chinese aviation gasoline chemical ingredient as well as differences of avgas between China and America. Binding the characteristics of this aero-engine, compression test and borescope inspection have been done on the affected cylinders, also an in-depth microscopic analysis on the deposit which has been accumulated on the cylinder, valve, spark plug and valve guide. Finally, solutions and recommendations are proposed to ensure the continuing safe operation of the engine and aircraft based on the analysis on obtained engine operation data. The reasons of valve sticking and valve breakage because of the lead built-up issue of reciprocation engine are not only the Tetraethyl lead content in Chinese avgas, but also engine operation conditions and levels of maintenances on engine.

A main oxidizer shut-off valve (MOV) controls the supply of cryogenic liquid oxygen to the combustion chamber of liquid rocket engines by on/off operation s. The main subjects to be introduced are not only the valve transient response during valve on/off procedures but also the characteristics of pneumatic and seat/poppet parts as core technologies in the dev elopment of the MOV, which is expected to be adopted for the Korea Space Launch Vehicle II. It is shown that the analytical prediction of the transient valve travel is in good agreement with experimental results. Friction and elastic forces on the valve moving part are quantitatively evaluated by structural analysis.

High contact stress between the vane tips and the cam ring is one of the main obstacles to improve the working pressure of a water hydraulic vane pump. A pressure-reducing valve for regulating the bottom pressure of the vanes at the pump suction zone is presented in this paper. Through optimization and simulation, it is found that the throttle structure has great influence on the dynamic performance of the pressure-reducing valve, and the triangular-rectangular groove is proved to be more suitable for the valve among all the investigated grooves. The theoretical analysis results show that the use of the pressure reducing valve can obviously reduce the contact forces between the cam ring and the vanes at the suction zone of the pump. The work in this research provides a feasible solution to improve the working pressure of a water hydraulic vane pump.

The working cycle of a reciprocating compressor results in the periodic impact of compressor valves. In order to find out the main cause for the excessive impact stress, this paper presents an experimental investigation on the valve dynamics especially the inclining angle and the impact velocity. The suction and discharge ring valves were redesigned and three displacement sensors were installed on top of the valve rings to measure the rings' instantaneous 3D motions, based on which the main factors that influenced the valve movements were identified by varying the valve installation position, clearance, working condition and the rotational speed. The inclining motion hardly happens as the valve is opening, while severe inclining motion takes place when the discharge valve is closing. When the pressure ratio is larger than 2.55, the inclining angle becomes uncertain because of the short time span of discharge process. The piston velocity and the volume of compression chamber at the valve opening moment have a direct impact on the maximum impact velocity. It displays a quick increase with the increase of pressure ratio and rotational speed while the valve installation position and the clearance have little influence on the maximum impact velocity. This experimental measuring method and results could provide useful information for both valve testing and optimization of valve reliability.

It has been analyzed the assembly of electromagnetic drive - inlet valve operating in camless valvetrain. The valve made of TiAl alloy has mated with its guide made of phosphor bronze. The scheme of electromagnetic valve drive has been shown in the article. The head aim of the motion control for such valve has been to provide small values of the valve velocity near the valve seat position. The aim of present analysis is to study the course of friction force between valve stem and its guide against time during use of control algorithm presented in the article. Curses of generated electrodynamical force against displacement of coil - valve assembly has been computed using FEM method and presented in the article. The courses of valve lift against time for different conditions have been presented in the article.

This paper presents an experimental study on the safety of a valve for a special gas cylinder. The test valves that were randomly dismantled from the special gas cylinder were experimented on the gas leakage and operation safeties. The crack, wear and deformation of the valve body, screw thread, safety disk, vent hole, stem and handle components that may affect to the gas leakage safety of a used valve were not found in this ex-perimental study. A painted handle of a valve was partly stripped from the coated surface, and the surface of PT screw of a used valve body was rusted. But, these paint and rust problems do not affected to the gas leakage safety of used valves. And there was no gas leakage in the dismantled valve, and the permanent deformation and partial scars of a valve stem and O-rings were observed on the rubbing surfaces. Thus, the valve seat and O-rings are recommended to be replaced for a gas leakage safety of a dismantled valve. And it is necessary to repair and inspect handle fastening forces for a safe opening and closing operations of a valve.Key words : special gas cylinder, gas leakage, valve, o-ring, valve stem, thread

The main inlet component of steam turbine is control valve. The stable operation of the steam turbine control valve is vital for safe and stable operation of the steam turbine and safety production of the power plant. However, due to the complexity of the structure and unsteady characteristics of steam flow in the valve, there is not enough experimental method about the detailed flow characteristics of the area near control valve disc and the inside of the valve chamber up to now. This article is to focus on the simulation of the steam turbine control valve interior flow field which includes the valve pre-inlet channel in different conditions, then find the reasons which caused instability and pressure loss of the control valve by analyzing the flow field details, finally further optimization design. The profile matching of the valve disc and valve seat has a great influence on the interior flow field of control valve, so analysis of the high performance valve disc shape and divergence angle of valve seat is carried out, and the research conclusion is used for guide design and development of the control valve.