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PurposeA self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.Design/methodology/approachThe self-adaptive piston device consists of symmetrical piston bodies, piston rings and other parts. The two piston bodies are linked by a ball-screw. The locking nut adjusts the distance between two piston bodies to avoid the piston rings from being stuck. The piston rings are placed between two piston bodies.FindingsThe simulation results based on COMSOL indicate that cylinder vibration caused by self-adaptive piston is 15.9 times smaller than the one caused by a traditional piston.Originality/valueThe self-adaptive piston is superior to the traditional piston in decreasing cylinder vibration.

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 this work, the influence of internal combustion engine parameters (cylinder-piston clearance, piston head height, the first segment position, gap of the first piston ring and gap of the second piston ring, piston rings’ axial clearance, intake valve debit coefficient) gas leakage from the combustion chamber through the piston rings’ area was investigated. This influence was studied by making an initial forming operation over gas leakage in the analyzed area.

The purpose of this investigation was to experimentally measure the motion of the floating valve plate in an axial piston pump under various operating conditions and to develop a model to determine how the floating valve plate motion affected the lubricating pressures between the valve plate and cylinder block. In order to achieve the objectives, a hydraulic circuit was designed and developed to incorporate and operate a floating valve plate axial piston pump. The hydraulic circuit integrating the axial piston pump (axial piston pump apparatus, APPA) consists of a series of valves, pressure sensors, a charge pump, flow meters, temperature sensors, a heat exchanger, and proximity probes. The floating valve plate axial piston pump housing was modified to incorporate three proximity probes to measure the valve plate position and motion relative to the cylinder block, thus allowing for determination of the film thickness within this contact. The results illustrate that as the pump starts up the valve ...

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.

Inside labyrinth piston compressor, the piston/piston rod system is main moving part. They suffer from very large periodically varying loads caused by gas force and inertia force. This may result in the piston rod’s bending and vibration. Therefore, the piston is always running eccentrically inside cylinder. It is difficult to calculate and predict the piston’s eccentricity accurately by the traditional analytical method. However, an accurate radial clearance between the piston and the cylinder wall must be calculated in the early design of the labyrinth piston compressor. Thus, this article proposes a new numerical method of studying the piston’s dynamic behavior, which is based on flexible body dynamics and finite element method. The method overall considers the piston rod’s characteristics of bending and vibration, effect of the radial clearance between the piston rod and the guide bearing, as well as crosshead and slideway. Through the model, the piston’s radial eccentric path can be better predicted. In addition, this article also introduces a new idea for realizing piston/piston rod system’s centering and utilizing an electromagnetic guiding system instead of traditional mechanical structure. The new centering technology will simplify greatly the inner structure of the compressor by removing the guide bearing. We have designed theoretically the structure of an electromagnetic guiding system and built its control model. Simulation verifies the effectiveness of this method, and good control result is obtained.

The construction of the piston groove seal of a volumetric hybrid energy-converting piston machine is proposed and investigated. A technique of assessing the overall performance of the proposed groove seal is developed and the influence of the basic construction and regime parameters on the overall performance of the seal is estimated.

All rights reserved. Linear compressors with clearance seals are well established for cryocoolers using either a Stirling cycle or pulse tube. However, both piston stroke and piston offset require detection and control in valved compressors. In order to manufacture linear compressor in large scale, then a simple, robust, and cheap control system is required with a minimum of sensors and actuators. This work introduces an approach to sensing the position of the piston using a search coil. The piston stroke is detected by calculating the peak-to-peak flux linkage in relation to the measured drive voltage and current. The piston offset is proportional to an integrated modulus of the back electromotive force (emf) of the search coil. Two PID (proportional-integral-derivative) controllers were developed to control the piston stroke by adjusting the drive voltage and a solenoid valve and bleed flow to control the piston offset. Experimental results validate the proposed compressor control technique.

A new integrated nozzle-flapper valve equipped with a piezoelectric actuator and an isothermal chamber has been developed and studied in detail. The designed single stage valve controls the pressure and flow rate simply, effectively, and separately. This idea can easily be used in the pilot stage of a two-stage valve as well. Application of isothermal condition in the valve load chamber eliminates the dynamic malfunction that may persist from temperature variation within the valve load chamber; consequently, the governing equations for the prediction of pressure dynamics in the chamber are much more accurate and simpler. The valve has been equipped with a stacked type piezoelectric actuator which has a unique behaviour. Furthermore, stiffness, in the selected actuator, is enhanced against the thrust of the discharging flow from the nozzle, thus decreasing the complexity of dynamic equations of the valve. A detail mathematical model and simulation was developed to study the dynamic performance analysis of the proposed valve. An experimental test rig was built to validate the results of simulations. The unique features and performance of the proposed valve were studied thoroughly. The valve's governing equations are nonlinear in nature, and some variables of the equations are a source of some uncertainties; sliding mode approach was used to control the steady and unsteady pressure and output flow rate of the valve. Namen predstavljene raziskave je uvedba novega ventila s šobo in odbojno ploščico (NF), za katerega so značilni spremenjen razpored delovnih elementov za izboljšanje dinamike, poenostavitev enačb ter odprava nekaterih omejitev tradicionalnih NF-ventilov. Za izpolnitev teh ciljev je bil novi ventil s šobo in odbojno ploščico zasnovan in opremljen s piezoelektričnim aktuatorjem in izotermno polnilno komoro. Dinamika polnilne komore, ki je glavni podsestav ventila, ima v celotni dinamiki ventila pomembno vlogo. Neobstoj točnega modela za spreminjanje stanja zraka v komori otežuje krmiljenje ventila. Zagotovitev izotermnih pogojev v komori ventila odpravlja dinamične napake zaradi temperaturnih sprememb v komori, vodilne enačbe za napovedovanje tlaka v komori pa so zato veliko točnejše in preprostejše. Izotermno stanje v komori ventila torej poenostavi njegovo krmiljenje, saj je le z enim samim tlačnim tipalom v komori ventila mogoče krmiliti tlak in pretok.

Precise engine valve lift control is essential in improving the efficiency of internal combustion engines and avoiding unwanted engine valve closure or mechanical interference between the valve and engine piston at different operating conditions. In this paper, a recently proposed hydraulic variable valve actuation (VVA) system [1] is equipped with a novel lift control architecture. In this technique, the hydraulic supply pressure is controlled using a proportional bleed valve. A discrete sliding mode controller is designed using the average model of the system on the basis of a discrete Lyapunov function. The stability of the designed controller is proven and sufficient conditions of the controller gains to stabilize the system are given. The experimental results show an excellent tracking performance of the proposed lift controller during sudden changes in the reference final valve lift. The results also show that using the proposed valve lift controller, the maximum lift deviation from its reference value does not exceed 0.4 mm during transient operating condition.

This paper introduces a new nozzle-flapper valve with isothermal chamber using piezoelectric actuator. It controls the pressure and flow rate simply, effectively and separately. The proposed valve uses isothermal chamber presenting practical isothermal condition due to its large heat transfer interfaces filled by metal wool. The valve uses stacked type piezoelectric actuator with unique advantages. By using this valve, a simple method has been fulfilled to control flow rate or pressure of ideal gases in a pneumatic actuators. Experimental results demonstrated applications of the proposed valve to control either pressure or flow rate in pneumatic circuits. This valve can be also used in the pilot stage valve to actuate the main stage of a much bigger pneumatic valve. Designated structure contains only one pressure sensor installed on the isothermal control chamber, capable of controlling both pressure and flow rate. The desired output mass flow rate of the valve is controlled by the pressure changes during positioning of piezoelectric actuator at proper position. The proposed valve can control steady and unsteady oscillatory flow rate and pressure effectively, using nonlinear control method such as feedback linearization approach. Its effectiveness is demonstrated and validated through simulation and experiments.

In this paper the fracture problem of exhaust valve of the piston engine was investigated. Visual inspection showed that on the fractured surface of the valve the beach marks, typical for fatigue failure were observed. The crack origin was not covered by corrosion products or material defects. In order to explain the reasons of damage of the valve, the non-linear finite element method was utilized. The numerical model composed of the poppet valve, the guide and the seat face was defined. In the analysis both the mechanical load resulting from the valve spring and also the thermal load arising from a non-uniform temperature field were defined. The loads were at first defined separately in order to check which load component has a dominant influence on the stress level. In third load case (which represents the operational thermo-mechanical engine conditions) the mentioned loads were defined simultaneously. The results of performed computations showed that the operational dynamic stress (in the critical zone of the valve where the crack appeared) is more than 12 times lower than the yield stress of the material. It means that the premature fatigue fracture of the valve was probably caused by any phenomenon concerned with the increase of the operational stress in the valve. The additional observation of the second (non-damaged) valve from the same engine head showed that the carbon deposit was located on the valve face. The results of the stress analysis of the valve with additional carbon particle showed, that in the valve stem a high bending stress was observed.

We report here, the design and characterization of a low power, low dead volume electrochemically driven micro valve. The valve can be operated with AAAA battery (0.125 mA-h/actuation at 1VDC) and is portable enough to fit inside a drug delivery device (size ∼18 mm × 18 mm × 13 mm). The electrochemical nature of the actuator allows for precise control of the valve diaphragm just by controlling the actuation voltage. The initial prototype is shown to withstand backpressure up to 5 psi, and is stable for more than 10 h of continuous operation. Three different design iterations are discussed with progressive improvement in terms of power and actuation time. The valve design and choice of material allows it to be mass manufactured by molding and easily sterilizable.

The pilot-control globe valve (PCGV) is a novel globe valve with a piston-type valve core and a small pilot valve. It can utilize a pressure difference to control the state of the main valve by the pilot valve. In this paper, a mathematical model of PCGV is established and a computational fluid dynamics (CFD) method is used to numerically simulate its flow and cavitation characteristics. Analysis of the pressure difference between the upside and downside of the valve core and comparison with similar previous work increase the reliability of the simulation. Then an analysis of flow and cavitation characteristics is carried out with three comparisons: a comparison between opened and closed states, a comparison between different inlet velocities, and a comparison between different valve core displacements. The results demonstrate that the vapor volume fraction reaches its peak point at the valve seat near the outlet tube, and that a higher inlet velocity or smaller valve core displacement can cause greater cavitation damage. This study can help further design work for optimization and engineering applications of PCGV.

The valves used to control or shut off the flow through a pipeline can be divided into many different types, including gate valves, globe valves, and check valves. Globe valves, in particular, have excellent properties, and because they can easily control the flow under high-pressure conditions, they are generally used in LNG ship and steam pipelines. In this paper, a method for changing the shape of a seat was suggested to solve the valve leakage problem from a structural perspective. In addition, the stress distribution and directional deformation were compared for each model. The suggested models were thus validated, and the optimized seat structure, which includes a self-supporting capability for decreasing the amount of leakage, was determined.

The article describes bench tests and calculations aimed to determining effect of parameters of ring-type elastic valve on variation of average pressure in the valve clearance. The results allow refinement of the design model of ring-type elastic valve and correction of the elastic ring cross-section based on the determined mechanisms.

Gas springs of the television is to control the piston speed when operating under along stroke(200~300 mm, television elevation)is possible. User by this principle is capable of elevation adjustment. First carried out a flow analysis of the piston. A piston speed adjustment technique for precise pipe type cross-section was examined. The piston structure for flow rate control and elevation action is proposed. This study is the development of a gas spring of more than 50 inch television with a large television stand. Hollow piston rod for optimal control(the outer diameter 19.9 mm, the inner diameter 13.9 mm) was injected into the nitrogen gas(0.3 mm/s) in. As a result, the flow rate the pressure drop of the piston rod as the increase was increased without any change of the external force. As a result, control of the displacement via the gas spring is possible. Keywrds : Gas spring, Labyrinth orifice, Piston, Pipe office

A novel electromechanical valve actuation system comprised of a linear actuator, valve, and energy storing cam/spring mechanism is presented. The system dynamics are modeled using Lagrangian mechanics, and a minimum-energy point-to-point optimal control problem is solved to find an optimal trajectory and input. The optimal input is used as a feedforward component in a transition controller to move the valve between the open and closed positions. Between transitions, a simple linear controller stabilizes the valve in the open and closed positions. A high-order model capturing the distributed nature of valve springs is used to validate state constraints related to positive cam/follower forces and a nonslip condition on the cam/follower. Finally, a prototype system is fabricated and tested with promising results.

Under consideration is the principal diagram of a percussive tool with a ring–shaped elastic valve installed in the air distribution system: the valve closes when contacting the housing and opens under action of elastic forces. The operability conditions and basic design parameters of the valve are determined. The authors characterize contact interaction between the ring–shaped valve and the side slide surface when the valve is closing. The balance of forces affecting the ring–shaped valve is shown.

We present a novel magnetic valving technology designed for lab-on-compact disc (CD) platforms. The working principle is based on a movable plug that, under the effect of the centrifugal force, can close off a channel. The channel can be reopened using magnetic force acting on the plug to lift off the plug from the valve seat. Different geometries and materials for the valve have been compared to optimize the manufacturability, closing (sealing), and opening properties of the valve. Among several materials tested as a valve seat, polydimethylsiloxane was found to be the best choice. Characterization and theoretical analysis of the implemented magnetic valve show that it can be efficiently used as an on–off active valve for a wide range of rotational frequencies. A theoretical model for description of the sealing properties of the valve was proposed and experimentally validated. [2014-0207]

This paper presents the prototype design and fabrication of a magnetically actuated miniature pump that utilizes self-sealing capability of ferrofluid-covered permanent magnets in both pumping and valving mechanisms. The valving action is performed by employing one active valve along with two nozzle/diffuser elements. Two cylindrical permanent magnets are placed inside the flat-wall channels: One magnet acts as the active valve and the other one serves as a reciprocating piston actuating the working fluid. In order to seal the gaps between the channel walls and the permanent magnet of the valve/piston, ferrofluid is used to cover the surfaces of both magnets. The valve and the piston are actuated using external permanent magnets driven by two separate stepper motors. Working with a stroke length of 20 mm at a driving frequency of 0.5 Hz, the pump is able to achieve a maximum flow rate of 1310 µL/min and a maximum 66 mm of water backpressure. The contactless external actuation feature of the design enables integration of the pump with other PMMA-based microfluidic systems with low cost and disposability.

A method of identifying solenoid valve transition events by analyzing the current through the solenoid coil is proposed. Solenoid valves experience lags and transition times which are non-trivial in the context of control methods that require precise valve timing. The proposed methodology allows a user to positively identify the beginning and end of valve transition events through identifying slope changes in the solenoid coil current traces. This methodology was shown to identify the timing of valve transition events with less than 7% error when compared to measuring the position of the valve spool with a laser displacement sensor. The proposed methodology is based upon measuring the current through the solenoid coil and requires no modification to the valve or valve housing to achieve these results.

This paper addresses a study undertaken to develop spatial numerical models of a piston, a piston pin and a connecting rod with reference to real components of a combustion engine crank system. The numerical studies conducted comprised an analysis of how the mechanical strength of piston pins was influenced depending on the change in their inner shape. For the purposes of calculations, various scenarios of shape modification were proposed for piston pins currently in use, enabling their weight to be reduced.

This paper proposes a method of diagnosing faults in reciprocating compressor valves using the acoustic emission signal coupled with the simulated valve motion. The actual working condition of a valve can be obtained by analyzing the acoustic emission signal in the crank angle domain and the valve movement can be predicted by simulating the valve motion. The exact opening and closing locations of a normal valve, provided by the simulated valve motion, can be used as references for the valve fault diagnosis. The typical valve faults are diagnosed to validate the feasibility and accuracy of the proposed method. The experimental results indicate that this method can easily distinguish the normal valve, valve flutter and valve delayed closing conditions. The characteristic locations of the opening and closing of the suction and discharge valves can be clearly identified in the waveform of the acoustic emission signal and the simulated valve motion.

The optimization of the valve plate transition region is an important way of reducing the noise emission for an axial piston pump. However, the optimized methods through simulation or experiment are actually trial and error, and they cannot indicate the precise structural parameters of the valve plate transition region. In this study, a new design method for the transition region of valve plate based on the matching of flow area and reduction of transient reverse flow was proposed, and with which a valve plate was designed. Then, the impact of the flow ripple in the discharge line of an axial piston pump and the pressure overshoot and undershoot in the piston chamber on hydraulic and structural noise for axial piston pump is discussed. The noise reduction effect of the axial piston pump with this valve plate was analyzed by adopting a flow characteristic simulation model. Finally, the results showed that the application of this design method could contribute much to the reduction of the flow ripple and elimination of the pressure overshoot and undershoot. As a consequence, the method can be used in the design of a low-noise open circuit axial piston pump.

High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system. However, traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously. A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system. A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design. Mathematical models of the opening process and flow rate of the valve are established. Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response. Corresponding formulas to solve 4 parts of the response time are derived. Key factors that influence the opening response time are analyzed. According to the mathematical model of the valve, a simulation of the opening process is carried out by MATLAB. Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve. Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool. The experimental results are in agreement with the simulated results, therefore the validity of the theoretical analysis is verified. Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa. The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s. According to the result of the load driving test, the valve can meet the demands of the driving system. The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.

This paper presents the realization of low, constant opening threshold pressures of an elastomeric valve by appropriate design and surface coating of the valve in a self-oscillating microfluidic device. The valve has a V-shaped valve seat, which separates the valve's inlet and outlet, and a membrane-pressurization bottom chamber. We utilized the V-shaped valve seat design to manipulate the mechanical deformation of the valve's membrane due to differences in applied pressure. Furthermore, we used a simple biomolecular surface coating to remove the adhesion force between the valve seat and the membrane. As such, the opening threshold pressure of our valve reduced from 13.1 to 2.4 kPa (i.e., an 81.7% reduction) at a flow rate 8 μL min−1. More importantly, we achieved a nearly constant opening threshold pressure regardless of the change in the input flow rate (i.e., a 0.07 kPa min μL−1 pressure change rate), thereby achieving a linear oscillating frequency response of the microfluidic device. Such a valve having low, constant opening threshold pressures is envisioned to be broadly useful for sophisticated fluidic routing applications, where numerous integrated valves with low actuation pressures are necessary.

In this paper the optimization of the spool and housing geometry in a small hydraulic seat valve to enable the reduction of the axial flow forces to a minimum value is described. Non-optimized hydraulic valve geometry is usually the main cause for many problems related to response time, actuation force and energy consumption. To overcome these limitations and problems we have done a thorough numerical and experimental analysis of a seat valve. The main influential geometry parameters of the seat valve are defined for numerical analyses. In the next step the basic theory of the numerical simulation, including the 3D modelling, meshing and parameterization, is explained. The reduction of the flow forces in a small hydraulic seat valve is treated in detail by using a commercial simulation tool, Ansys CFX. The validation of the numerical fluid model of the valve is done by comparing simulation and experimental results obtained with the test rig for axial flow force measurement. With the validated numerical fluid model of the valve new fluid models are built taking into account all influential geometry parameters of the valve for the purpose of the final optimization of the valve geometry. The results of the simulation analyses show that the axial component of the flow forces can be reduced significantly just by modifying the geometry of the valve spool and housing. Thus the valve dynamic characteristics, such as response time, are significantly improved while the necessary actuation force and power consumption are reduced.

Use the 3D software and FEA for designing the valve controlling pneumatic actuator and the core components, which is a kind of efficient way to inspect the functions and safety. Also this way can optimize the production structure and increase the reliability.

The main objective of this work is to perform numerical analysis of an electromagnetic normally-closed direct-acting ball valve with cylindrical seat. A functional diagram is developed using the MATLAB/Simscape/SimHydraulics programming language. The principal elements of the functional diagram are: the fixed-displacement hydraulic pump, the ball valve which is driven by an electromagnetic actuator, the pressure-relief valve, pressure and volumetric flow rate measuring devices and the hydraulic pipes. Two sets of analyses are performed, the first one for an ideal case, without the effects that are associated with the hydraulic pipes and the second one for the real case, with these effects. The valve flow factor is presented, comparatively, for both cases, as well as the volumetric flow rates through the ball valve and the pressure relief valve, and finally the pressure drop in the valve.

The paper analyzed the temperature field and the thermal stress field of a diesel engine piston with finite element analysis software ANASYS, then used the thermal mechanism indirect coupled method, researched the coupled stress field of piston. The result indicated that the point of the highest temperature located on the middle of firebox which under the dangerous temperature of the material; under thermal stress effect, the max displacement of the piston did not exceed the clearance between piston and cylinder liner, but the non-roundness at the third ring reached 0.08mm, which had some influence on the pressurize and lubricate of piston; under thermal mechanism coupled effect, the point of max stress located on the interface of the seat of the pin and the pin hole, so as the top on the pin hole and inner on the seat of pin, so it was recommended to set rib between cervix and the seat of pin of piston to enhance the practical carrying capacity of the seat of the pin.

The distinctive features of contact interaction between seat and wedge in gate valves are investigated using a finite-elements analysis program. It is shown by the example of DN400 valve that the forces of interaction between the seat and the wedge are unevenly distributed over the area of their contact. To avoid failure, the forces of contact interaction must not be excessively large. However, weakening of contact interaction increases the risk of loss of leak-tightness of the seat–wedge junction.

In order to develop a new type of high-performance axial piston pump, the impact of the dynamic response characteristics of piston chamber pressure to the stability of cylinder block were analyzed. This paper a new type of valve plate which combined two fixed throttling grooves with a triangular groove (called three-level gain) was put forward so as to reducing the excessive pressure adjustment of the dynamic response of piston chamber pressure and improving the stability of cylinder block. The simulation results indicate that not only the cavitation is reduced, but also the stability of the dynamic response of piston chamber pressure is remained at various swash plate angle which makes it applicable to variable piston pump. The results also indicate that the flow pulsation of variable displacement pump is significantly decreased in different operating conditions.

To assess piston’s thermal loads, the direct and effective method is to calculate piston’s temperature distribution. A key point in calculating the temperature field of a piston is the determination of heat transfer boundary conditions of each side, especially the gas side. The thermal boundaries of a piston consist of the piston top side (combustion side), the crevice surfaces, the piston ring land and skirt outside surface, piston underside and pin hole side.The calculating methods for the heat transfer boundary conditions of engine piston are studied according to the theoretical analysis of heat transfer of engine piston, which can be taken as a reference for providing precise boundary conditions for the research on piston’s temperature field.

Due to the ability of the strong anti-interference and directly digital controlling, digital valve has great applications and developing potential in the filed of high frequency response digital servo valve. Base on the rotating structure, a novel high frequency digital valve which can be rotated and controlled in differential parallel way is designed, and the frequency characteristic of electrical signals converting into rotation signals is developed through differential and parallel control of valve spool and valve sleeve. Meanwhile, the hydraulic natural frequency of servo-screw mechanism is further enhanced by the control way of hydraulic half-bridge type A in both chambers of valve spool, and corresponding mathematical model and control block diagram are built. Theoretical analysis concludes that the frequency response characteristic of digital valve is developed significantly. In addition, the multi-gain of rotation angle and axial displacement of valve spool is realized through milling the spiral grooves with different helix angles in the inside of valve sleeve, which improves the flow adaptability of high frequency digital valve effectively. Compared to traditional rotary digital valve, the designed novel digital valve that can be controlled by rotating differentially and parallel has greater advantages in high frequency response and flow adaptability, it provides a new scheme for engineering applications of high frequency digital valve.

The intermittent transient contact of the piston skirt and cylinder liner is related to the secondary motion of the piston. The instantaneous piston secondary motion measured using laser displacement sensors can indicate whether the piston skirt is in contact with the cylinder liner. The force of the impacting piston skirt on the cylinder liner can be calculated using the equation of motion, which allows the piston skirt friction force to be distinguished from the total friction force and friction torque. The results showed that the piston skirt friction force contributes as much as 44% of the overall piston assembly friction force.

The piston slipper in an axial piston pump demonstrates most complicated dynamic motions: two rotations (tilting toward to the swash plate and rotating about the pump shaft) and one translation together with the pumping piston. In addition, the slipper is used to lubricate the swash plate surface with hydraulic oil, but prevents high pressure fluid escaping from the piston bores. In hydraulic engineering, improper designs of the piston and slipper assembly cause many instability and unbalance issues while the slipper attempts to lift and tilt off the swash plate. This may cause catastrophic failure and damage to a piston pump. To suppress the undesirable motion is one of most design difficulties that might take a range of different dynamics into consideration and compromise the design parameters of piston assemblies.In this study, the complicated dynamics are simplified and linearized with some assumptions that are able to apply stability conditions. The dynamic response of the assembly as operating needs...

A mathematical model of the working process of a piston pneumatic engine with self-acting air distribution that takes into account the dynamics of the mechanism of movement along with the results of experimental and theoretical studies are presented. Recommendations to improve the constructions of the new type of piston pneumatic engine are given.

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.

Because of industrial development, industrial facilities are becoming more complex and diversified. Plant industries are focused on productivity improvement, cost reduction, and product uniformity by simplifying production processes using automated control. Furthermore, plant industries require higher pressures and temperatures to improve energy efficiency. For this reason, the valves used in plants are operated under harsh conditions. Globe valves and gate valves are mainly used for high pressure these days. However, these valves have various problems, including low maintainability and high cost, due to structural problems. Therefore, butterfly and ball valve applications are increasing in industrial plants. This paper suggests a quadruple-offset butterfly valve that is applicable to bi-direction use, and the principle design parameters are suggested. The selected design parameters are an eccentric flange center line and shaft centerline(Offset 1), an eccentric seat centerline and disc shaft centerline(Offset 2), the angle between the flange center line and seat wedge angle(Offset 3), the angle between the vertical direction of the disc shaft centerline and seat centerline(Offset 4), and the seat engagement angle. To analyze the interaction effect of the design parameters, ANOM and ANOVA were performed with an orthogonal array. The parameters were found to have effects in the following order: Offset 2, Offset 1, engagement angle, Offset 3, and Offset 4. The interaction betwe en the parameters was insignificant.

In this paper, pneumatic valve which consists of valve body, valve controller, nozzle and a multi-bender PZT actuator was suggested and fabricated. The fabricated pneumatic valve was experimented for performance evaluation. From the experimental results, we know that the flow rate of the suggested valve is 23 lpm at the pressure difference of 1bar and the maximum flow rate is 30 lpm at the pressure difference of 4 bar. The flow rates after endurance test of 9.8 million were 22.57 lpm and 28.62 lpm at the pressure difference of 1bar and 4bar, respectably. Finally, it was verified that the B10 life of the suggested pneumatic valve is over 50 million.

Pneumatic mechanism widely used in industrial, automotive, aerospace, and etc. The principle of pneumatic like piston is move up and down due to the air pressure inside the piston. Mechanism of piston can be applied to the power plant that utilizes the ocean waves where as use of piston mechanism is very helpful in solving the problem of fossil fuel scarcity as a source of energy in power plants. In this study we will focus on the pneumatic system which utilizing ocean wave that moves longitudinally to encourage buoy that located on the piston shaft to up and down and then the pressing of air out of piston. Output of the piston will be forwarded to the generator (rotor and stator) to produce a voltage. In this paper is focused on the manufacture of pneumatic systems and processes to produce the rotation and voltage. Material of piston tube component made of aluminum and rubber, buoys made of plastic and generator such as of metal and copper coils. Output of the piston will be forwarded to the generator (rotor and stator) to produce a voltage. In this paper is focused on the manufacture of pneumatic systems and processes to obtained the rotation and voltage with aluminum for piston tube material, buoys made of plastic and magnet rotor and copper coils of stator include on the generator and get the results of ocean wave power plant using piston mechanism is 1400 rpm with a voltage of 36 volt.