Search

Permanent magnet linear synchronous motor (PMLSM) has a wide application prospect in transmission systems of automatic production, logistics and other fields. However, the existing PMLSM has the problems of poor flexibility and large thrust fluctuation adapted to load and stroke variation. In order to solve this problem, a dual-modular PMLSM is proposed. The motor can be flexibly configured with multiple-unit-primary (MUP) and multiple-unit-secondary (MUS), and achieve low thrust fluctuation. The matching criterion of unit-primary (UP) and secondary is established to reveal the relationship between the slot/pole combination and the winding utilization. The rules of the average thrust varying with the different UP and unit-secondary (US) lengths are illustrated. Then, the matching criterion of different UP is proposed, and the optimization method of the spacing between UP (S1) is obtained by establishing the end force model. The design standard of the optimal S1 is obtained by combining the two factors of minimum detent force and maximum thrust. The results are verified by the simulation and experiments on a 3UP-96US dual-modular PMLSM circular transmission line system and its prototype.

The increasing demands in modern combustion engines for low emissions and low fuel consumption improved methods for the cycle of combustion. The Beare Heads is a recent 6-hour version of the Beare Heads, recognized also as Malcolm Beare model. Beare Heads uses pistons and harbours such as a 2-hour motor and replacements for the overlap valve system of 4-hour motors. The four-stroke engine, block as well as shaft remain intact. The six-time engine was a mix of two-hit and four-hit technologies. Six Stroke is a six-stroke engine that uses two energy strokes. The six-time engine including external combustion as well as internal dual stream is the same as the real interior combustion engine, according to its mechanical design. Air heating system as well as a combustion chambers, each separate of the cylinder, are two extra chambers throughout the thermodynamic cycles. The six-stroke is heat efficient, since the power pulse pressure changes are larger than for the injection process as well as compression strokes. The major benefits of six-stroke engines included lowering fuel consumption by 40 percent, reducing emissions, versatility for multi-fuel service by 2 power strokes over the six-stroke cycles.

This article presents a novel state estimator for short-stroke reluctance actuators, intended for soft-landing control applications in which the position cannot be measured in real time. One of the most important contributions regards the system modeling for the estimator. The discrete state of the hybrid system is treated as an input. Moreover, the model is simplified to facilitate the identification of parameters and the implementation of the estimator. Thus, auxiliary variables are added to the state vector in order to indirectly account for modeling errors. Another important contribution is the state estimation approach. It is based on the Rauch–Tung–Striebel fixed-interval smoother, which allows refining past data from later observations. Numerous simulations are performed to analyze and compare the proposal and several alternatives. In addition, experimental testing is presented to evaluate and validate the estimator. As the simulated and experimental analyses demonstrate, the combined effect of the novel additions results in significantly smaller estimation errors of position and velocity.

The complex wing motion of insects and small birds leads to high lift production in nature. Specific lift-enhancing mechanisms arise from the combination of a horizontal stroke motion and a seconda...

The Camshaft is a vital part of the Internal Combustion engine of automobiles. It functions as a timing mechanism that controls the opening and closing of the inlet and exhaust valves, as well as the valve overlap that occurs at the TDC of the exhaust stroke. The camshaft is made up of several journals that run on bearings within an engine. The camshaft is bound to rotate with the crankshaft by either a set timing gear, timing belt, or timing chain. As the camshaft drive fails, the valves and piston crowns come into contact, causing extensive internal damage. For high-speed diesel engines (Compression Ignition), power impulses have a greater value than spark-ignition engines in multi-cylinder configurations. In this study, a comparative analysis of an existing automobile camshaft of four-stroke, a four-cylinder Compression Ignition (CI) engine made of Cast Iron was carried out with different compositions of metal matrix composites. For this condition, the outcomes were taken as Von-Mises stresses and displacement values for the static state of the camshaft. The modal analysis (Free vibration) was performed using ANSYS after the static analysis results were obtained. Finally, comparing all the results obtained for different materials, the AlSiC 20% metal matrix composite has been recommended as the most suitable material for the production of camshafts which can replace cast iron because of its similar behavior as to cast iron. This will aid in the development of more precise camshafts, which will be useful for larger displacement engines.

In the era of upcoming electric technology, internal combustion engines are somewhat losing their edge in terms of the emissions and performance parameters when they are compared to electric and hybrid vehicles; to tackle this situation many of the automotive manufacturers are optimizing their engines to get better performance and reduced emissions. The quest for increasing efficiency, reducing emissions has been taking place ever since the invention of this dependable workhorse of the automobile realm. Currently, a whole lot interest has been on reducing emissions and increasing efficiency by reducing heat losses to the fluid in the energy stroke of the cycle. Ceramic coatings play a major effect in reducing emissions, increasing efficiency and in reducing damage and abrasion failure in internal combustion engines. This paper offers an overview on the numerous aspects and utilization of ceramic coatings on internal combustion engines like performance characteristics, emission characteristics and combustion characteristics and their properties.

In this work, a novel dual‐stator hybrid excited linear flux switching machine (DSHELFSM) is proposed. The proposed machine is suitable for long‐stroke applications as all the excitation sources are mounted on a short mover and the stator is completely passive. Second, the proposed machine uses ferrite magnets rather than the expensive rare earth permanent magnets (PMs) with the addition of field excitation to achieve flux‐regulation capability at various field currents. An iron bridge that provides an additional path for flux linkage to complete its circuit is used. Various design parameters such as split ratio, stator pole width, width and height of PM, the width of the iron bridge, width of mover's tooth, and stator slot depth are optimised using multivariable geometric optimisation (MGO) while keeping the slot area, electric and magnetic loading constant. The optimised design has improved the performance as compared to the initial design. Furthermore, the results obtained by 2D analysis are verified by 3D analysis. Thermal analysis is carried out to set the operating limit of the proposed machine.

The focus of this paper is on the verification and validation of computational approaches commonly used for the simulation of in-cylinder processes involving intense turbulent flow and combustion. Furthermore, the tumble behavior during the intake stroke at different engine operating points is investigated since the cycle-to-cycle variability of the subsequent tumble breakdown at the end of compression stroke is reported to negatively affect the engine efficiency. In this respect, measurements with advanced laser diagnostics-based experimental techniques (TR-PIV) in an optically accessible engine have been performed and compared with LES for flow in the same engine, under identical operating conditions. The study focused on the intake stroke under wide open throttle conditions and engine speed of 1000 RPM and 1500 RPM. The ensemble averaged velocity fields of the two methods were analyzed and compared. A counter-clockwise motion and some secondary recirculation zones were identified and quantified in both methods. The same trend for tumble ratio was observed between experiments and simulations and a good agreement was found for most CAD especially at 1500 RPM. At 1000 RPM comparison showed significant variations, which after a detailed analysis of the instantaneous fields, are attributed to the strong cycle-to-cycle variability of the instantaneous tumble center. It is observed, that for relevance index values below 0.75 the ensemble averaged flow fields that the two methods predict significantly differ.

Large-stroke rapid motion is required in many industrial servo systems (e.g. pick-and-place applications), on which constraints of control input and motion speed are usually imposed. This paper presents a hybrid control scheme for large-stroke rapid motion in such systems. The controller resorts to the time-optimal control (TOC) for maximum acceleration initially and then switches into a linear control law to achieve smooth settling. A speed regulation stage is inserted in the tracking process to prevent violating the speed constraint. To tackle the unmeasured speed and unknown disturbance, an extended state observer (ESO) can be included in the controller. The controller is applied to a permanent magnet synchronous motor (PMSM) servo system for large-stroke position regulation. Digital simulation via MATLAB is conducted first, followed by an experimental verification using a TMS320F28335 board. The results confirm that the proposed controller can track a wide range of target references with desirable performance under speed constraint and load disturbance and has a competitive advantage over the popular active disturbance-rejection control (ADRC) scheme.

Nowadays, the feeding systems of computer numerical control machine tools are lubricated by periodic oil supply or fixed stroke, the lubrication is insufficient in the case of high load and high-speed movement, and the lubrication is excessive during finishing and low feed rate. This study discusses the optimum lubrication timing of the feeding system. When the feeding system is moving, the servomotor torque value and current, accuracy, and oil film thickness are measured by sensors. Moreover, the lubrication characteristic model is validated and built by using the sensor values, and the optimal lubrication state estimation is obtained by using the back-propagation neural model. Then analyzed and feedback to the machine tool controller, to intelligent the lubrication system. According to the test, when the feed rate is increased by 5 m/min, the friction coefficient increases with rate, increasing the output of the frictional value of the work table by 6.90%. When the load is increased by 175 kg, the friction coefficient decreases with load, reducing the frictional value output of table movement by 6.71%. In the relationship between oil film thickness and current, the accuracy difference between the prediction and actual test results is less than 10%; in the case of the same accuracy, the oil supply frequency is reduced by 80%, and environmentally friendly machine tool has been achieved.

This study investigates the relationships between boat velocity, stroke rate and displacement per stroke in Paracanoe 200m Sprint Kayak races. Data were analysed from 646, 200m efforts performed by 13 international Paracanoe athletes between 2017 and 2020 (Male: N= 6, female: N= 7) using boat-based GPS unit (Catapult S5). Significant differences between the Paralympic classifications were observed for boat velocity, stroke rate and displacement per stroke across both genders (p < 0.001) and Paracanoe classification (p < 0.001). Stroke rate was found to be the best predictor of boat velocity across classifications explaining between 13% and 34% of the variation. However, displacement per stroke was found to be more important for males than females potentially due to strength and anthropometric differences. Boat velocity, stroke rate and displacement per stroke values for the final 150m (measured in 50 m splits) indicated evidence for a mix of all-out and positive pacing strategies. The results of this study suggest intricate differences exist in Paracanoe Sprint Kayak based on gender and classification between athletes. This information is useful in the coaching of Paracanoe Sprint Kayak with evidence that physical preparation, training, and race strategy can be individualised to each athlete.

Hofbauer cycle machine is one promising technology for heating. It has many advantages compared to conventional Vuilleumier machines due to its non-continuous motions. However, its non-continuous motions also bring challenges for control. In this work, a simplified dynamic model is proposed to predict the free stroke for control. Based on assumption of a mass-spring system for the displacers, a simplified solution is deduced. The simplified solution is based on constant position of pressure balance points and a linear change of gas mass in the working chamber. Experiments on a prototype machine were carried out to validate the model. Motions of displacers are analyzed and causes for abnormal motions are revealed. Then, the predicted free stroke is obtained based on the simplified model and compared with the measured results. The relative error is in the range of -2.45% ∼ +3.02%. Thus, the simplified model could provide a reference for quick control in Hofbauer cycle machines.

In this paper, an experimental test rig has been developed by utilising the free-piston linear generator (FPLG) principle of a dual-piston air-driven system. The mechanical energy of the FPLG is converted into electric power through a linear generator. The piston motion, root mean square (RMS) power output, operating frequency, system stability and the conversion efficiency of the FPLG at various inlet pressure and valve opening duration (VOD) are duly discussed in the paper. It is noticed that the piston displacement (stroke) is associated with the VOD and inlet pressure, which have the greatest effect on the FPLG motion characteristics. A long VOD leads to a high piston speed, causing high peak power output. However, the RMS power shows an approximately linear decline with the increase in VOD due to the free-piston dwelling for a certain time at the dead centre position before the exhaust process starts. The FPLG can be achieved a maximum RMS power of 120 W when the inlet pressure is 8 bar and VOD is 30 ms. When the inlet pressure changed from 8 bar to 5 bar, the FPLG operating frequency shows a similar trend and values because it is associated with the piston velocity and stroke. The FPLG Cycle-to-Cycle variation (COV) is low when the inlet pressure is high, and the system stability increases with decreases in VOD. As the VOD increases, the indicated efficiency and work to electrical efficiency increase, whereas the thermal to work efficiency decreases. The maximum indicated efficiency, work to electrical efficiency and thermal to work efficiency achieved are 59.9%, 14.7% and 14.6 %, respectively.

A novel bionic piezoelectric actuator based on the walrus motion to achieve high performance on large working stroke for micro/nano positioning systems is first proposed in this study. The structure of the proposed walrus type piezoelectric actuator is described, and its motion principle is presented in details. An experimental system is set up to verify its feasibility and explore its working performances. Experimental results indicate that the proposed walrus type piezoelectric actuator could realize large working stroke with only one driving unit and one coupled clamping unit; the maximum stepping displacement is ΔLmax = 19.5 μm in the case that the frequency f = 1 Hz and the voltage U = 120 V; the maximum speed Vmax = 2275.2 μm · s−1 when the frequency f = 900 Hz and the voltage U = 120 V; the maximum vertical load mmax = 350 g while the voltage U = 120 V and the frequency f = 1 Hz. This study shows the feasibility of mimicking the bionic motion of the real walrus animal to the design of piezoelectric actuators, which is hopeful for the real application of micro/nano positioning systems to achieve large working stroke and high performance.

This paper presents the results of experimental research on the development and substantiation of parameters and operating modes of the drive mechanism of the cutting apparatus in a mower with a double knife stroke. A structural and technological scheme of the drive mechanism of the cutting device of the segment-finger type mower has been developed, in which a double stroke of the cutting device knife is provided. Analytical relationships were obtained to determine the knife stroke, speed and acceleration. Based on the results of theoretical and experimental studies, the main parameters of the mower drive mechanism were substantiated. Based on the condition of a high-quality cut of plants, at a minimum grass cutting speed, the minimum crank shaft speed was determined. By calculation, the feed area and the load area of the cutter for normal cutting with a double cut of the knife are determined. Analytical relationships were obtained to determine the power required to drive the cutterbar of a mower with a double knife stroke. Based on the research results, the main parameters of the mower with an improved drive are substantiated. An experimental sample was made and preliminary tests of the drive mechanism were carried out, agrotechnical and energy indicators of the mower operation were determined., В данной работе представлены результаты экспериментальных исследований по разработке и обоснованию параметров и режимов работы механизма привода режущего аппарата косилки с двойным проходом ножа. Разработана структурно-технологическая схема механизма привода режущего аппарата косилки сегментно-пальцевого типа, в которой предусмотрен двойной проход ножа режущего аппарата. Были получены аналитические зависимости для определения прохода, скорости и ускорения ножа. На основании результатов теоретических и экспериментальных исследований были обоснованы основные параметры механизма привода косилки. Исходя из условия качественного среза растений, при минимальной скорости скашивания травы была определена минимальная частота вращения коленчатого вала. Расчетным путем определяются площадь подачи и площадь нагрузки резца при нормальной резке с двойным проходом ножа. Были получены аналитические зависимости для определения мощности, необходимой для привода режущего аппарата косилки с двойным проходом ножа. По результатам исследований обоснованы основные параметры косилки с улучшенным приводом. Был изготовлен экспериментальный образец и проведены предварительные испытания механизма привода, определены агротехнические и энергетические показатели работы косилки., У даній роботі представлені результати експериментальних досліджень з розробки та обґрунтування параметрів і режимів роботи механізму приводу ріжучого апарату косарки з подвійним проходом ножа. Розроблено структурно-технологічну схему механізму приводу ріжучого апарату косарки сегментно-пальцевого типу, в якій передбачений подвійний прохід ножа ріжучого апарату. Були отримані аналітичні залежності для визначення проходу, швидкості і прискорення ножа. На підставі результатів теоретичних і експериментальних досліджень були обґрунтовані основні параметри механізму приводу косарки. Виходячи з умови якісного зрізу рослин, при мінімальній швидкості скошування трави була визначена мінімальна частота обертання колінчастого вала. Розрахунковим шляхом визначаються площа подачі і площа навантаження різця при нормальному різанні з подвійним проходом ножа. Були отримані аналітичні залежності для визначення потужності, необхідної для приводу ріжучого апарату косарки з подвійним проходом ножа. За результатами досліджень обґрунтовані основні параметри косарки з поліпшеним приводом. Був виготовлений експериментальний зразок і проведені попередні випробування механізму приводу, визначені агротехнічні та енергетичні показники роботи косарки.

Besides electrification of the powertrain, new synthetic alternative fuels with the potential to be produced from renewable sources come into focus. Methanol is the most elementary liquid synthetic fuel and no novelty for use in internal combustion engines. This article presents pathways to achieve high efficiency spark-ignition methanol combustion on a direct injection spark-ignition single-cylinder research engine with two different stroke-to-bore ratios (1.2 and 1.5) and a constant bore. In addition, two compression ratios (CRs) were investigated on each setup: CR = 10.8 using RON95 E10 gasoline fuel and a higher CR = 15 using neat methanol. In contrast to previous studies of stroke-to-bore ratio influences on SI combustion, this article aims at demonstrating how the advantages of a high stroke-to-bore ratio can be exploited by combining a long-stroke engine with increased compression ratios and methanol. The increased stroke enhances the tumble motion due to a higher piston speed and a larger compression volume which improves the mixture homogenization and combustion velocity. Moreover, the lower surface/volume ratio results in a reduced heat transfer. When using RON95E10 gasoline fuel and CR = 10.8, an efficiency gain of up to 1.6% could be achieved with the long-stroke compared to the short-stroke especially at lower engine loads. With methanol and CR = 15, an efficiency gain of up to 1.6% could be achieved with the long-stroke setup compared to the short-stroke engine. Subsequently, lean burn conditions were experimentally investigated with methanol and CR = 15. The longer stroke allowed the lean burn limit to be extended from λ = 1.9 to λ = 2.0 with an efficiency gain of up to 2.2%. A maximum indicated efficiency of 47.4% could be achieved at λ = 1.9 with methanol on the long-stroke engine with CR = 15.

The specificity of the operating conditions of agricultural tractors in the agro-industrial complex requires the provision of reliable engine start at low ambient temperatures. Improving the starting qualities of a diesel engine and reducing incomplete combustion in the post-start period can be achieved by increasing the exergy of the air charge at the end of the compression stroke or increasing the exergy of the fuel injected into the combustion chamber. The purpose of the study is to reduce the expenditure of exergy for prestarting a diesel engine, improve starting qualities and reduce incomplete combustion in the post-start period. To achieve this goal, the design of an electric heat exchanger was developed in the form of a coil from a high-pressure fuel line, into which a heating element is inserted. A method for calculating its main parameters was developed. Calculations showed that in order to ensure reliable start-up of a diesel engine in winter, it is necessary to heat the fuel in the nozzle to a temperature of 240 C in the thermal boost mode. A heater of about 98 Watts is required to reach this temperature within 270 seconds of priming. However, in order to maintain such a fuel temperature during the start-up process, it is necessary to make changes in the nozzle design in order to minimize heat losses into the walls of the fuel channel by applying a heat-insulating coating. With further engine operation in the post-start heating mode, the fuel temperature in the injector is reduced to 8595 C.

A valve assembly used in nuclear power plants must be qualified and supervised. New technical standards such as ASME QME-1 2007 particularly require detailed qualification using experiment and analysis. Particularly, diagnostic tests and engineering studies are required for qualification of ASME QME-1 2007. Among these studies, the research on the measurement of friction coefficient and packing stress is important. The irregular change of packing stress along the stroke distance occurs because of the abnormal phenomenon, which must be found and studied with quantitative methods. Packing stress should be analyzed conservatively through experimentation and analysis. In this study, various formulas were applied to measure and calculate coefficient of friction and packing stress. This study can be used in relation to qualification and supervision of packing materials. And the calculation using static diagnosis test can be used to find the packing frictional force in dynamic diagnosis test with flow pressure in a pipe. This study has made it possible to reliably consider packing frictional force generated in a valve body. And so, it is believed that more margin can be secured when evaluating the capacity of valve actuator by applying the accurate frictional force generated in the valve assembly.

In this study, lightning-induced currents due to a triggered lightning with a strike distance of 8 m were measured at an unenergized 200-m overhead line. The characteristics of the coupling current excited by four return strokes were analyzed in time and frequency domains, respectively. Moreover, a 3-D finite-difference time-domain (3-D FDTD) model was built to calculate the coupling current, which was verified by comparing the simulation results against the recorded data. The influence of the constant return stroke velocity and the variable velocity on the coupling current was analyzed by using the 3-D FDTD model. The results indicate that the lightning-induced currents on the overhead line are significantly affected by the nonmonotonically variable return stroke velocity.

Penelitian tersebut menyajikan mengenai pengujian mesin sepeda motor 4 tak terhadap pengaruh tenaga, torsi dan emisi gas buang. Proses meningkatkan performa mesin yaitu memperluas langkah piston dan meningkatkan volume udara di intake dan saluran bahan bakar ke ruang pembakaran mesin. Proses dilakukan dengan overstroke yang meningkatkan volume step dengan cara menambah panjang piston sehingga terjadi kompresi rasio meningkat, dan oversize ruang bakar dengan ukuran yang lebih besar menjadi 200 cc. Pengujian dilakukan di Bengkel Teknik Mesin Otomotif Politeknik Dharma Patria Kebumen. Pengujian Tersebut dilakukan sebanyak 3 kali pengulangan untuk mendapatkan hasil yang maksimal. Tujuan penelitian untuk meningkatkan performa mesin dilihat dari data tenaga, torsi dan emisi gas buang yang didapat dari pengujian menggunakan gas analyzer. Dalam penelitian ini dilakukan pengujian secara langsung pada mesin gas analyzer dengan tiga kondisi yaitu pada rpm 1000, rpm 2000 dan rpm 3000. Hasil pengujian dengan modifikasi mesin gas analyzer menunjukkan HC 41 ppm dan kadar CO sebesar 4,3 % , angka tersebut menunjukan kadar gas buang menjadi lebih baik.

Ring gear is an important part of high-power transmission system. Because of its thin wall and low stiffness, it is easy to produce deformation in the process of gear shaping, which affects its accuracy. In order to ensure the machining quality of gear shaper, this research focuses on the typical material 42CrMo, which is used in the gear ring of automobile gearbox. Through the finite element simulation and actual test, the influence of gear shaper cutting parameters on the deformation of gear ring is studied. The results show that the influence of the main cutting parameters on the deformation of the ring gear is in the order of radial feed, circumferential feed, stroke speed and cutting depth. In the actual gear shaping process, the cutting parameters can be adjusted according to the deformation law of 42CrMo workpiece in the gear shaping process, so as to control the deformation of gear ring.

The article considers one of the topical directions of increasing fuel economy and reducing the toxicity of exhaust gases, namely, cylinder disconnection of internal combustion engines (ICE) in idling and partial loads. Current internal combustion engines with cylinder disconnection have enough technical solutions to ensure high fuel economy and ecological indicators of the engine working process. Accordingly, such engines require solution of the following tasks: improvement of mass-size indicators, cost reduction and design improvement, increase of reliability, etc. One of the main tasks of transport vehicles is also reducing the level of engine vibrations. This task is especially relevant for internal combustion engines with disconnected cylinders. When cylinders are disconnected, the unevenness of total torque increases from working processes in active cylinders and, as a result, the unevenness of the engine stroke, which affects the dynamic characteristics of the vehicle as a whole. To solve this problem, the general provisions of torsional momentum unevenness of internal combustion engines were considered. Total torsional torque of different engines was processed and data on the unevenness of torsional torque was obtained. The method of investigating the influence of cylinder switching, particularly the number of active cylinders on the unevenness of total torque is developed. The notion of torsional torque change degree with cylinder disconnection is introduced and the equation for its determination depending on the number of active cylinders is proposed. The notion of torsional torque coefficient change at disconnection of cylinders is also introduced. The application of the calculation of a four-cylinder inline engine for the possibility to compare changes in the torsional momentum unevenness when the cylinders are disconnected in the given engine was made. As a result of the calculations it was found that the torque unevenness coefficient at operation of the engine with 3, 2 and 1 cylinders in the average increases in 1,5; 2 and 3 times. The results of calculations were analyzed and histograms for all possible values of the number of active cylinders have been provided.

Plane strain compression of cylindrical billets with flat dies has been studied in this paper. A deformation model has been proposed and the dimensions of the deformed billet cross-section for a given press stroke have been determined. To analyze the process, two types of theoretical approaches, i.e., the upper bound technique and the slab method of analysis have been applied and the required forming load has been estimated. Analytical results of billet cross-section deformed geometry and compression load have been compared with the finite element data obtained by the DEFORM 2D ver11.0 finite element package. It is shown that there is a satisfactory agreement between the theoretical predictions and the FE simulation data. The solution can be used in industrial applications for evaluating the required press load to deform the long circular cross-section billets, which is essential for selecting the forming machine with enough capacity.

Introduccion. En nuestro país se ve la falta de abastecimiento de repuesto en particular los pistones de tiempos para motor de motocicletas, dado que la producción de este elemento solo se da en países tales como: Alemania, Argentina, España, Turquía, Gran Bretaña, Estados Unidos, Brasil, Japón, China e India, siendo estos los pioneros que abastecen el stock de recambio tanto a nivel mundial como en Latinoamérica. Objetivo. Obtener un proceso de obtención de un pistón de 100 CC de dos tiempos aplicando la ingeniería inversa a partir de un pistón comercial mediante el empleo de diferentes ensayos como: espectrometría, ensayo de dureza y micrografía. Metodología. Para la obtención de la misma se ha elaborado a partir de pistones reciclados como fuente de materia prima, contribuyendo además con el medio ambiente al reutilizar los pistones que están fuera de servicio, por otra parte, para el proceso de fundición en molde de arena se ha basado en normas e investigaciones previas para reducir efectos como el exceso de porosidad, fracturas, etc., puesto que pueden influir en el producto final. Posterior a ello tras obtener el pistón, mediante los ensayos mencionados se realiza una comparación entre el obtenido y el original, adicional con un ensayo de tracción aportar con datos como el esfuerzo ultimo de tracción y el límite de fluencia. Resultados. De esta manera se obtuvo un pistón funcional además se concluye que durante la fundición es importante considerar que el silicio por acción de la temperatura disminuye su porcentaje en masa, factor importante ya que como elemento químico es difícil de encontrar en el mercado.

Piston slap is the primary source of noise and vibration in an Internal Combustion Engine. In this work, an experimental study of influence of piston pin-offset on reducing noise and vibration due to piston slap is described. The vibration and noise signals are acquired experimentally on time response and then these are plotted on frequency response. The noise levels of the engine operating at maximum pressure at TDC (Top Dead Center), BDC (Bottom Dead Center) and at the middle of the stroke are captured. These correlation results show that maximum values of vibration and noise levels correspond to the TDC region where the stress levels are high. Hence, design optimization of the piston, cylinder-liner and other parts can be made to minimize the stress values so that the corresponding noise level is also minimized. One of the methods to minimize the piston slap noise is by providing the piston pin-offset. In the present study, the piston geometry is redesigned for the pin-offsets of 0.2, 0.3 and 0.4 mm. The noise and vibration frequency spectrum and plots of the noise levels (air borne) in terms of dB(A) are obtained by conducting experiments on a running Internal Combustion Engine. It is found from these observations that there is an improvement observed for both stress values and reduction in noise intensity, for the piston pin-offset of 0.3 mm, of the Internal Combustion Engine considered for the study.

PurposeThe different performance tests were conducted on diesel engine compression ignition (CI) mode and CRDi engine.Design/methodology/approachThe CI engine was suitably modified to CRDi engine with Toroidal re-entrant combustion chamber (TRCC) and was run in dual-fuel (DF) mode. Hydrogen (H2) was supplied at different flow rates during the suction stroke, and 0.22 Kg/h of hydrogen fuel flow rate (HFFR) was found to be optimum. Diesel and biodiesel were used as pilot fuels. The CRDi engine with DF mode was run at various injection pressures, and 900 bar was found to be optimum injection pressure (IP) with 10o before top dead center (bTDC) as fuel injection timing (IT).FindingsThese operating engine conditions increased formation of oxides of nitrogen (NOx), which were reduced by exhaust gas recycle (EGR). With EGR of 15%, CRDi engine resulted in 12.6% lower brake thermal efficiency (BTE), 5.5% lower hydrocarbon (HC), 7.7% lower carbon monoxide (CO), 26% lower NOx at 80% load as compared to the unmodified diesel engine (CI mode).Originality/valueThe current research is an effort to study and evaluate the performance of CRDi engine in DF mode with diesel-H2 and BCPO-H2 fuel combinations with TRCC.

In this paper the numerical model that calculates the fluid dynamics in an engine cylinder which is represented in the first part of this paper (1) is used to simulate the comp ression stroke. The calculated results are presented For a cupped piston geometry under op erating conditions typ ically of those contemplated for direct injection diesel engine Particular emphasis is p laced on the sp atial and temporal distribution of the Flow, velocity vectors and contour lines, Swirl intensity and swirl centers. Although many of the detailed features of the turbulent flow are still unresolved, some progress of the understanding of the in-cylinder flow specially near the top of the dead center (TDC) is gained.

This paper presents a method for predicting the in-cylinder gas flows during the intake stroke of four-stroke engines. A simplified engine model with a deep-bowl piston configuration, and a central intake valve was used. An inviscid two-dimensional axisymmetric flow was investigated. The model used a finite difference procedure with an expanding/contracting grid in axisymmetric representation. The major source of troubles for the convergence of the solution was the unsteady turbulent jet flow issuing from the intake valve which required very small time intervals for the solution compared with that during the compression stroke where there is no jet flow exists. Results show a complicated flow field during the intake stroke in engine like-geometries.

A novel pneumatic-electric hybrid actuator is studied and developed to enable precise positioning within a cylinder stroke in industrial automation. The proposed actuator will also allow engineers to overcome the defects of bias torque and structural coupling in the parallel type of pneumatic-electric hybrid actuators. The novel hybrid actuator consists of a coaxial cylinder layout, the motor lead screw pair, and the position sensor; a serial driving pattern is applied. A special reconfigurable positioning structure is designed for both the fixed and moving module; therefore, a decoupling motion can be achieved for the fast pneumatic motion and the electric precise fine-tuning motion without interference. In this paper, the authors presented the structure of this novel pneumatic-electric hybrid actuator and the accompanying mathematical model for pneumatic-electrical driving. Additionally, the control strategy with proportional-fuzzy mode and the subsection frequency control mode are presented. Experimental results show that the pneumatic-electric hybrid actuator has satisfying motion characteristics, including high speed, low overshoot, and small load sensitivity. Its positioning accuracy is ±0.01 mm, with a positioning time within 2 s, which is better than that of current pneumatic localizable actuators and pneumatic-electric hybrid actuators.

Shear cutting is one of the most widely used manufacturing processes in the production of sheet metal components. The reasons for this are the high output volume combined with low costs per part. The profitability of this process is significantly influenced by the lifetime of the active elements and the occurrence of unexpected process disturbances. While there are already many publications on the former, there are only few examinations on the wide spread process disturbance of slug pulling, which describes the phenomenon where the cut-out part is pulled upwards again during the punch return stroke. In particular, the different forces on the slug that cause this phenomenon have not yet been measured individually and independently of one another in one single tool. Thus, a shear cutting tool was developed that enables the measurement of the individual forces on the slug depending on various process parameters. Following, single stroke experiments were carried out to determine these forces and establish relationships between the process parameters, the characteristics of the slug and the measured forces. Finally, the interaction of all partial forces depending on selected process parameters is discussed in order to classify the relevance of every single force with regard to the occurrence of slug pulling. This understanding of the process is necessary in order to make a well-founded decision when designing future tools or selecting available remedial measures to avoid slug pulling.

The moving-coil type voice coil motor (VCM) has very light moving mass, which can achieve higher reciprocating frequency and work efficiency. However, the power supply lead connected to the moving coil can be easily broken under long-term reciprocating motion, so it is rarely used in compressor drive systems. The core technology of the compressor development trend is a driving motor with high-efficiency, high reciprocating frequency, certain piston stroke, and light moving mass. Due to its structural characteristics, the moving-coil type VCM has broad application prospects. This article proposes a new structure for power supply of a moving coil VCM based on the principle of electromagnetic induction. The proposed VCM can overcome the problems of aging and disconnection of power supply lines caused by reciprocating motion, and meet the requirements of high-frequency and long-term repetitive action of the moving coil. The content of this article is as follows. First, the construction of the proposed VCM is introduced. Second, the power-driven circuit based on interleaving double switch forward converter is provided. Finally, two working modes of drive circuit for reciprocating motion are proposed. Simulation and experimental results verify the effectiveness of the method.

The pneumatic systems have lower energy efficiency than the electric and hydraulic systems. Improving the utilisation rate of compressed air is an important aspect for increasing the energy efficiency in the pneumatic systems. This paper introduces two methods for reducing air consumption, including the quantitative air intake method and the optimisation of the air intake and exhaust duration method. The quantitative air intake method analyses the minimum air consumption volume in a specific pneumatic system based on the energy conservation theory. The optimisation of the air intake and exhaust duration method aims to find the best air intake and exhaust time schedule by the mathematical optimisation of the energy‐saving and system stability of the pneumatic systems. An experimental equipment was established to verify the theoretical results of the two methods. Based on the experimental results, this paper analyses the characteristics and accuracy of the two methods and discusses the applicability of mathematical optimisation under some different boundary conditions. The experimental results show that both of the two methods can effectively reduce the air consumption in the piston stretching‐out stroke and save 76% of the air consumption compared with continuous air intake during the whole stroke.

A new type of negative stiffness friction damping device (NSFDD) was developed in this study, which can solve the problem of poor energy dissipation of the existing passive negative stiffness damping device. The friction force is generated by squeezing the friction plate with the preloaded nitrogen spring vertically. When the NSFDD is working, the friction plate causes the nitrogen spring to rotate and negative stiffness force and friction force are generated. The results of the performance test show that the NSFDD can achieve negative stiffness in the hysteretic model. Comparing with the existing negative stiffness device, the NSFDD has larger stroke, more stable negative stiffness and better energy dissipation capacity. The finite element software has been used to simulate the low cycle reciprocation of a structure, and the results show that the NSFDD reduces the stiffness of the structure while increasing the damping of the structure. The results of the simulation and analysis of the shock absorption plan of the NSFDD show that the NSFDD reduces the stiffness of the floor, thereby effectively control on the shear force, displacement and acceleration response of the structure.

This work explores pathways to achieve diesel-like, high-efficiency combustion with stoichiometric 3-way catalyst compatible combustion in a single-cylinder spark ignition (SI) research engine. A unique high stroke-to-bore engine design (1.5:1) with cooled exhaust gas recirculation (EGR) and high compression ratio ( rc) was used to improve engine efficiency by up to 30% compared with a production turbocharged gasoline direct injection spark ignition engine. Engine experiments were conducted with both 91 RON E10 gasoline and liquified petroleum gas (LPG) (i.e. autogas) and were compared to legacy gasoline data on the production engine. Geometric compression ratio ( rc) of 13.3:1 was used for both fuels with additional experiments at 16.8:1 for LPG only. Measurements of exhaust soot particle size and number concentrations were made with both fuels. Significant reduction in soot particles across the whole particle size range were achieved with LPG due to the elimination of in-cylinder liquid films. The effects of EGR, late intake valve closing (IVC) and fuel characteristics were investigated through their effects on efficiency, combustion stability and soot production. Results of 47% gross thermal efficiency, and 45% net thermal efficiency at stoichiometric engine operation, at up to 17 bar IMEP and 2000 r/min with 16.8:1 rc were achieved with LPG. Estimated brake efficiency values were compared to a contemporary medium duty diesel engine illustrating the benefits of the chosen path for achieving diesel efficiency parity.

To better understand the formation and evolution processes of soot, the two-color laser induced incandescence diagnostic method was applied on a single cylinder optical direct injection spark ignition engine. Soot volume fraction was measured, and soot distribution was imaged as cyclic fuel quantity changes. The results show that 45.5 mg/cycle generates the most soot at the same measure plane. Pool fire dominates the formation of soot in the tested engine and generates more soot on the top surface of the piston near the injector. In-cylinder soot increases until 42°CA ATDC and then reduces due to oxidation. Pool fire continues through the expansion stroke till 52°CA ATDC, and then soot cloud gathers near the 10 mm plane. After 82°CA ATDC, in-cylinder soot basically in equilibrium, and residual soot moves follow the in-cylinder flow randomly and evenly distributes within the whole combustion chamber. With increasing cyclic fuel quantity, particles number concentration gradually increases and their distribution present dual-peak shape. In detail, 45.5 mg/cycle emits the most accumulation mode particles while 52 mg/cycle emits the most nucleation mode particles.

Dielectric elastomer actuators (DEAs) have been shown to produce electrically induced strains beyond 500%. The ability to undergo large deformation allows the DEA to store large amounts of elastic energy by electrical actuation; it also allows the DEA to perform flexibly in a diverse range of motions. Existing studies used different methods to maximize actuation strain for soft robotic applications. In this article, we examine the actuation of our antagonistically coupled DEAs, reminiscent to that of human muscles. We perform an analysis to reveal optimal conditions that maximize its actuation stroke, actuation force, and output energy. We quantify actuation stroke by the displacement sweep due to electrical actuation, between two fixed points, expressed as a percentage, and refer to this as "actuation sweep." From the analysis, we predicted an optimal prestretch for the DEA that corresponds to a 59% actuation sweep. In our experiment, we realized a 55% actuation sweep. We further characterized the output force and the mechanical work done for complete performance appraisal of the antagonistic system both theoretically and experimentally. We realized an antagonistic soft actuator system with simple geometry that provides significant electrically induced displacement, force, and work done, similar to that of biological muscle systems, and demonstrated its efficacy.

The capacitive micromachined ultrasonic transducer (CMUT) has inherent advantages, such as larger bandwidth and monolithic integration capability with electronics, when compared to the piezoelectric transducer. The most significant shortcoming of the device is the trade-off between input and output sensitivities. Adequate receive sensitivity requires an electric field intensity on the order of 105 V/m, which can be achieved by sub-micron gap heights. However, a small gap limits the device stroke and, consequently, the maximum output pressure. This paper addresses this problem by proposing a CMUT with a vertical cavity. The membrane of the device has a piston part that is surrounded by the sidewalls of a vertical cylinder formed in the substrate. The fringing electric field pulls the piston in the vertical direction; hence, the gap height remains fixed, which alleviates the hard limit on device stroke. The performance of the proposed device is compared to that of the conventional CMUT by theoretical and analytical methods, and a micro-fabrication method is devised. Additionally, a millimeter-scale device has been manufactured and tested as a proof of concept.

The present article considers operating processes occurring in a positive displacement two-stage piston hybrid energy-generating machine having a gas cap. The conducted numerical experiment revealed the physical picture of viscous fluid flow, as well as the features associated with implementing a mathematical model of these operating processes. It was found that a change in any of the independent parameters leads to a corresponding change in the amount of fluid entering the second-stage working chamber of the machine, the maximum and minimum fluid levels, the liquid piston stroke, clearance space volume, as well as the amount of fluid ejected into the compressor discharge line. The presented ranking of the obtained results shows that the discharge pressure of compressible gas has the greatest influence on the operating processes.

Variable displacement compressor technology can achieve high steady-state efficiency, non-start/off operation thus high seasonal efficiency and capacity modulation. A comprehensive thermal-economic-environmental analysis of a household refrigerator with variable displacement compressor using three refrigerants (R134a, R152a and R1234yf) was presented using CoP and normalized CoP, set-up and running cost and Life Cycle Climate Performance, respectively. The results indicate that with the application of variable displacement technology, the compressor stroke can be tuned in response to heat load so that the power consumption is reduced thus the running cost and CO2 emissions. When the compressor stroke using R134a drops from 13 mm to 10 mm, the power consumption, total cost and life cycle CO2 emissions decrease by 86.3%, 56.7% and 59.9%, respectively. Running cost accounts for 89% of the total cost while indirect emissions accounts for 98% of the total CO2 emissions. Replacement of R134a by R152a will decrease the CoP by 10% but also reduce the cost and CO2 emissions by 5% and 8.6% respectively. This is comparable to increasing the R134a system CoP by 0.9. It is indicated that by adopting variable displacement technology, more CO2 emissions could be reduced given that part load represents over 80% of operating hours for refrigerators.

Free-piston linear generator (FPLG) engines currently gained great attention due to their capability to operate with variable fuel and compression ratio. This paper presents an experimental study on the effect of aspect ratio on the performance characteristics of the FPLG engine fueled by hydrogen. Three aspect ratios (i.e. 1.0, 1.5, and 2.0) are used to identify the engine combustion and performance parameters. The injection position is fixed in the middle of the stroke, while the equivalence ratio is kept at 1.0. The results indicate that the aspect ratio 2.0 produces the highest pressure, heat release, and shortest combustion duration. Whereas the aspect ratio 1.0 produces higher combustion efficiency and operating frequency. The piston speed decreases with the decrease in aspect ratio, which gives a negative effect on the indicated mean effective pressure and power output of the PFLG. Overall, the aspect ratio has a significant influence on engine performance characteristics.

A two stage esterification process was adopted in producing biodiesel from Jatropha curcas seed oil in a modified batch reactor. The produced fuel was washed and dried before testing it in an unmodified single stroke diesel engine. 10 liters of biodiesel was measured into five containers and blended with fossil diesel at various percentages for optimal performance in the following order; 10% (B10), 20% (B20), 50% (B50) and 70% (B70) while the fifth container was used as control at 100% biodiesel (B100). Constant engine speed test was conducted to investigate the performance of the produced fuel at known operational speeds of most farm machines. Two engine speeds were selected (2000rpm and 1500rpm). Each speed level was selected on the engine when no extra load was on it, then load from the dynamometer was gradually imposed on the system. A drop in speed was noticed and the engine was raised back to the selected speed. It was allowed to stabilize for about 3minutes before recording the spring readings on the tension side of the belt (F₁), and that on the slack side of the belt (F₂), and torque (T) on the belt and other parameters were deduced. The result of the experiment showed the high torque delivering ability of biodiesel and its blends (B10 & B20) and their ability to protect the enginewhile in operationby reducing frictional wear and tear given its high viscosity.

Frequency domain information were extracted from the time domain electric fields pertinent to the lightning positive return strokes applying Fourier transform and Wavelet transform. The electric field radiated by positive ground flashes striking the sea were recorded at 10 ns resolution at a coastal station to minimize the propagation effects. The frequency spectrum of the electric field of positive return strokes were computed applying the Fourier transform technique in the range of 10 kHz to 20 MHz owing to the fact that this range of frequency is of very much interest to the researchers and design engineers. The amplitude of the energy spectral density decreases nearly as ƒ-1 from 10 kHz to about 0.1 MHz and drops nearly as ƒ-2 up to 8 MHz. Applying the wavelet transform technique, the same positive return strokes are found to radiate in the frequency range of 5.5 to 81 kHz with the average spread distribution of 13.6 kHz to about 30 kHz. From frequency spectrum obtained from the Fourier transform it is difficult to identify as which phase of the return stroke radiates in the higher frequency range and that in the lower frequency range, whereas, one can easily identify from the frequency spectrum obtained with the wavelet transform that ramp portion of the positive return stroke radiates in the larger spectral range as compared to that of initial peak of the return stroke. Also, from the spectral density map obtained from wavelet transform one can easily observe the contribution of each phase in a range of frequency, which is not possible from the Fourier transform technique. Clearly, the wavelet transform is much more powerful tool to extract the frequency domain information of a non-stationary signal as compared to that of Fourier transform.

The main purpose of this study was to explore the impact of the wrist joint movement on the stroke effect, especially that of the angular velocity and linear velocity on the ball speed and spin spe...