Investigation of a Switch-Off Time Variation Problem of a Fast Switching Valve

2014 ◽  
Author(s):  
Rudolf Scheidl ◽  
Christoph Gradl ◽  
Helmut Kogler ◽  
Paul Foschum ◽  
Andreas Plöckinger
Keyword(s):  
Mathematical Models ◽  
Time Variation ◽  
Peak Current ◽  
Manufacturing Error ◽  
Variation Problem ◽  
Switching Valve ◽  
Fast Switching ◽  
Series Of Experiments ◽  
Current Value ◽  
Off Time

In a series of experiments the peak current during switch on of a fast switching valve, which was found to be out of tolerances with respect to some armature dimensions, was varied to realize different switch on times. Despite the fact that the holding current was identical for all cases and the time between switch on and off was very long, the valve’s switch off time showed an unexpected dependency on the switch on peak current value. This paper presents an explanation of this phenomenon by coarse mathematical models, demonstrating that the manufacturing error in combination with friction, skewness, and fluid stiction are responsible for this behavior.

scholarly journals Experimental Validation of Mathematical Framework for Fast Switching Valves Used in Digital Hydraulic Machines

2015 ◽  
Author(s):  
Christian Noergaard ◽  
Daniel B. Roemer ◽  
Michael M. Bech ◽  
Torben O. Andersen
Keyword(s):  
Experimental Validation ◽  
Switching Time ◽  
Optimization Method ◽  
Input Power ◽  
Mathematical Framework ◽  
Hydraulic Motor ◽  
Switching Valve ◽  
Fast Switching ◽  
Hydraulic Machines ◽  
Series Of Experiments

A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based on an elaborate optimization method the valve is designed to maximize the efficiency of a digital hydraulic motor targeted to a wind turbine transmission system. The optimisation method comprises a mathematical framework which predicts a valve switching time of approximately 1 ms with a peak actuator input power of 10 kW during switching (mean of approximately 250 W) and a pressure loss below 0.5 bar at 600 l/min. The main goal of this article is validate parts of the mathematical framework based on a series of experiments. Furthermore, this article aims to document the experience gained from the experimental work and to study and assess a moving coil actuators suitability for the application.

Mathematical Modeling of Machining Parameters in Electrical Discharge Machining with Cu-B4C Composite Electrode

2012 ◽  
Vol 488-489 ◽  
pp. 871-875
Author(s):  
V. Anandakrishnan ◽  
V. Senthilkumar
Keyword(s):  
Mathematical Models ◽  
Current Pulse ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Machining Parameters ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time ◽  
Selection Of

Copper based metal matrix composite reinforced with Boron Carbide is a newly developed Electrical Discharge Machining (EDM) electrode showing better performance than the conventional copper based electrode. Right selection of machining parameters such as current, pulse on time and pulse off time is one of the most important aspects in EDM. In this paper an attempt has been made to develop mathematical models for relating the Material Removal Rate (MRR), Tool Removal Rate (TRR) and Surface roughness (Ra) to machining parameters (current, pulse-on time and pulse-off time). Furthermore, a study was carried out to analyze thSubscript texte effects of machining parameters on various performance parameters such as, MRR, TRR and Ra. The results of Analysis of Variance (ANOVA) indicate that the proposed mathematical models, can adequately describe the performance within the limits of the factors being studied. Response surface modeling is used to develop surface and contour graphs to analyze the effects of EDM input parameters on outer parameters.

Non-linear dynamic modelling of a switching valve driven by pulse width modulation in the hydraulic braking system of a vehicle

2016 ◽  
Vol 231 (11) ◽  
pp. 1511-1529
Author(s):  
Xiang Gao ◽  
Yiyong Yang ◽  
Xun Zhao ◽  
Chenfeng Li
Keyword(s):  
Fluid Dynamics ◽  
Dynamic Modelling ◽  
Stability Control ◽  
Dynamics Model ◽  
Predictive Tool ◽  
Element Analysis ◽  
Linear Dynamics ◽  
Switching Valve ◽  
Fast Switching ◽  
Non Linear

Fast-switching valves driven by puse width modulation have been widely used in the hydraulic braking systems (such as anti-lock braking systems or electric stability control systems) of vehicles, because of their lower cost and their functions which are similar to those of proportional valves. However, proportional valves have been widely investigated, whereas there is significantly less literature on the switching valves of the hydraulic control units in the braking systems of vehicles. In order to investigate the controllability of pressure, construction of an accurate theoretical model is the key to attaining this. Based on theoretical analysis and finite element analysis, this paper presents a non-linear dynamics model of a typical fast-switching valve. The non-linear model is composed of three submodels: a mechanical submodel, an electromagnetic submodel and a fluid dynamics submodel. The fluid momentum theorem combined with the simulation curve-fitting method is used to model accurately the fluid dynamics which are due to the varying flow field. The hydraulic force acting on the spool can be obtained directly from this model. Finally, the feasibility of the response time and the pressurization performance of the non-linear dynamics model is proved by comparing the simulation results from MATLAB/Simulink with the experimental results obtained on a test bench. The study shows that the model can be regarded as a predictive tool for future investigation.

scholarly journals Electrochemical Response of Clay/Polyelectrolyte Composite Barrier Coatings

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1173
Author(s):  
Sumin Kim ◽  
Clare Chisu Byeon ◽  
Sung Yeol Kim
Keyword(s):  
Mass Transport ◽  
Indigo Carmine ◽  
Copper Substrate ◽  
Layer By Layer ◽  
Potential Cycling ◽  
Peak Current ◽  
Redox Peak ◽  
Coated Electrode ◽  
Redox Peak Current ◽  
Current Value

Composite materials made of polymer and clay are effective at blocking mass transport. In this study, the blocking efficacy of layer-by-layer (LbL) coatings of exfoliated montmorillonite (MMT) and polyethylenimine (PEI) was studied using cyclic voltammetry and a redox couple, indigo carmine (IC). The pH of the MMT solution was varied from 4 to 10 to prepare LbL coatings of different surface roughness on metal substrates. It was found that the coated electrode had a lower redox peak current value than without the coating, demonstrating the reduction of the mass transport of IC to the metal surface. The peak values decreased with decreasing the coating’s roughness and increasing the number of layers, indicating that the blocking capability can be controlled by changing the deposition conditions. Smooth LbL coatings deposited with MMT at pH 4 showed the highest blocking efficacy up to 97.5%. The IC adsorbed at the interface between the coating and the metal substrate was found to cause the peak current measured for the coated electrode. It was also confirmed that the same coating on the copper substrate reduced the corrosion of the copper during the electrochemical potential cycling.

Experimental Validation of Flow Force Models for Fast Switching Valves

2017 ◽  
Author(s):  
Niels C. Bender ◽  
Christian Noergaard ◽  
Henrik C. Pedersen
Keyword(s):  
Velocity Profile ◽  
Surrounding Medium ◽  
Squeeze Film ◽  
Switching Valve ◽  
Fast Switching ◽  
Material Contact ◽  
Analytic Expressions ◽  
General Dynamics ◽  
Visible Effect ◽  
Squeeze Effect

This paper comprises a detailed study of the forces acting on a Fast Switching Valve (FSV) plunger. The objective is to investigate to what extend different models are valid to be used for design purposes. These models depend on the geometry of the moving plunger and the properties of the surrounding medium. A few analytic expressions have been suggested in the literature and these have been supported by CFD simulations, yielding accurate coherence for a large part of the fluid domain. However, when a moving body approaches a stationary body, squeeze film effects will occur if the plunger velocity is non-zero. This is the case in FSVs, where it results in an additional dampening effect, which is of relevance when analyzing contact-impact. Experimental data from different tests cases of a FSV has been gathered, with the plunger moving through a medium of either oil or air. This data is used to compare and validate different models, where an effort is directed towards capturing the fluid squeeze effect just before material on material contact. The test data is compared with simulation data relying solely on analytic formulations. The general dynamics of the plunger is validated for the established models, but an additional investigation of the dampening force is necessary. Therefore, numerical analyses are introduced to enhance the knowledge of the hydrodynamic end dampening. This has a visible effect on the velocity profile at the end-stop. This profile represents the measurements more accurately, but it is not possible to verify the velocity profile at the valve seat end-stop due to measurement uncertainties.

Study on Fabrication and Fast Switching of High Voltage SiC JFET

2013 ◽  
Vol 827 ◽  
pp. 282-286
Author(s):  
Gang Chen ◽  
Song Bai ◽  
Run Hua Huang ◽  
Yong Hong Tao ◽  
Ao Liu
Keyword(s):  
Gate Voltage ◽  
Room Temperature ◽  
Inversion Layer ◽  
Oxide Semiconductor ◽  
Low Loss ◽  
Semiconductor Interface ◽  
Fast Switching ◽  
High Temperature Operation ◽  
Off Time ◽  
Channel Region

SiC devices have excellent properties such as ultra low loss, high withstand voltage, large capacity, high frequency, and high temperature operation compared with Si devices. The SiC JFET is expected to be appropriate for the power device because a JFET has no oxide-semiconductor interface in the channel region and does not use the low mobility SiC MOSFET inversion layer as a channel. Forward I-V up to 4A for SiC VJFET, Gate voltage from 2V to 3.5V by step 0.5V. Reverse I-V characteristics up to 4500V (VG=-8V) for SiC VJFET, Gate voltage from-4V to-8V by step-2V. Turn-off characteristics are studied and fast turn-off time of 136ns at room temperature under DC voltage of 600V is successfully demonstrated.

Evaluation of Cutting Rate for Ultrasonic Work Piece Vibration Assisted Wire-EDM under Varying Amplitude of Vibration

2020 ◽  
Vol 979 ◽  
pp. 149-156
Author(s):  
Sanjay Kumar ◽  
Sandeep Grover ◽  
Ravinder S. Walia
Keyword(s):  
Cutting Speed ◽  
Work Piece ◽  
Cutting Condition ◽  
Time Level ◽  
Peak Current ◽  
Optimum Cutting ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time ◽  
Level 2

This paper present an investigation on cutting speed of ultrasonic vibration assisted wire electrical discharge machining (US-WEDM) for High carbon high chromium D3 Steel. An extensive research study was carried out with an aim to select the optimum cutting condition with the varying amplitude of vibration in order to get the optimum cutting speed for the proposed set-up. The process was mathematically modeled using the response parameters, i.e. cutting speed under a range of control parameters and the main influencing factors were determined for cutting speed criteria Taguchi’s experimentation methodology indicated the contribution of amplitude of vibration (P=6.16%), pulse on time (P=14.54%), pulse off time (P=73.16%) and peak current (P=5.94%). Finally, the optimum parametric setting for different cutting speed arising out of study has synthesized as amplitude of vibration at level 3 (18μm), peak current level 1 (100 units), pulse on time level 2 (118 μ sec) and pulse off time level 2 (46 μ sec) and analyses in this study.

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