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The relevance of the study is associated with the need to implement the concept of the scientific and technological development of the Russian Federation, which outlines the transition to environmentally friendly and resource-saving technologies. The paper presents the results of full-scale experiments of changes in the operating parameters of the experimental-industrial hybrid solar hot-water system with a circulating pump operating in periodic duty mode in the hydraulic circuit. The proposed hardware and software system provides switching on and switching out of the circulating pump depending on the temperature difference of the coolant in collectors and at the storage tank output. This provides the maximum thermal energy for the hot-water system at different of solar radiation intensities and the minimum power consumption by the circulating pump generated by solar panels.

As obras subterrâneas encontram-se associadas aos aproveitamentos hidroelétricos nos seus elementos principais: na barragem, contribuindo na satisfação das exigências de comportamento estrutural e hidráulico-operacional, e na central e circuito hidráulico, como elementos fundamentais do sistema hidráulico que possibilita a produção de energia. Neste artigo, são focadas obras subterrâneas realizadas, ao longo de um século, nos grandes aproveitamentos hidroelétricos de Portugal, dando-se destaque às obras consideradas mais relevantes pelo seu layout ou pelas suas características específicas. Nas obras mais recentes, é dada relevância a aspetos relacionados com análises numéricas, segurança, monitorização estrutural e ambiental, estratégias e métodos construtivos.

The use of solar energy in isolated sites for different applications, such as water pumping, is of primary interest to people in developing countries who do not have safe access to water drinking. But photovoltaic generators have two major drawbacks that are a low yield and a high blow. In order to increase the performance of these systems. Proper adaptation between the solar generator and the load reduces the cost of installation. The choice of an energy system must obey and comply with certain rules. The selected energy system must show as a preliminary its competitiveness with respect to other systems for the same rendered service. The present study have a propose the modeling, simulation, sizing and realization of a photovoltaic pumping system operating over the sun. This system consists of a set of interacting elements; namely the photovoltaic panels, the voltage inverter, the asynchronous motor, the centrifugal pump and the hydraulic circuit.

This paper presents ${a}$ new, and efficient, wear debris detection sensor based on passive wireless LC sensing approach. This sensor enables online monitoring of metal debris in hydraulic flow tubes with large thickness, employed in high-pressure applications. In conventional inductive debris sensors, the coil is kept outside the tube. $(i)$ Hence, for thick tubes, the sensitivity is extremely low. If the coil is kept inside the tube, holes are required to connect it to the measurement unit (MU). (ii) This limits the pressure withstanding capacity. The proposed sensor solves these two problems using the wireless LC sensor approach, wherein the MU is connected to an outer coil (outside the thick tube), and an inner coil is kept close to the oil, with debris. Thus, it is highly sensitive to the debris. It requires no electrical connection to the MU. The outer coil is energized from an AC signal at the parallel resonance frequency of the system, drawing minimum current from the source. The change in phase of this current, due to the change in inductance of the inner coil as debris passes, is measured using ${a}$ phase-sensitive detector. This highly sensitive measurement approach together with the fact that the inner coil is close to the oil, helps to achieve high sensitivity, and enables monitoring flow tubes with large diameter and thickness. ${A}$ prototype of the proposed wireless LC debris sensor has been developed (inner and outer diameters of 25.4 mm and 80 mm respectively), integrated into ${a}$ hydraulic circuit and tested. The output was not only very sensitive to ferrous and non-ferrous metallic particles but also helps in distinguishing them.

Vegetable oils are well known for their potential applications in green chemistry, including use as hydraulic fluids. Among oilseed crops, Crambe abyssinica Hochst. EX R.E.Fr . gained attention for its low-input requirements during cultivation and for the properties of its oil, characterised by a high erucic acid content. This long-chain mono-unsaturated fatty acid provides appreciable features that make the oil suitable for interesting green chemistry sectors, as biolubricants and cosmetics. In the present work, Crambe oil was tested as a hydraulic fluid for sustainable agricultural applications. Crambe oil was partially refined through phospholipid removal and added with a food-grade antioxidant (tert-butylhydroquinone) at two different concentrations. The fluid efficiency tests were carried out using an experimental test rig, able to simulate a real hydraulic device, performing heavy work cycles at 40-MPa pressure and at 100 °C temperature, with the aim of strongly accelerating the ageing of the tested fluid. At a lower antioxidant concentration, 0.25 g kg−1, the oil underwent a very quick degradation process. However, increasing the additive dose to 2.0 g kg−1, the fluid maintained stable performances. Indeed, all parameters, referred to oil chemical-physical stability and technical performance, were constant along the entire work cycle, up to 290 h. Finally, the present work showed how Crambe seed cultivation, oil extraction and exploitation in the hydraulic circuit of farm machinery could be developed applying green chemistry approaches aiming at small-scale biorefineries linked to the local supply.

Purpose. The aim of this work is to develop an effective solar hot water system, which eliminates the heat loss of the accumulated thermal energy in the storage tank due to the natural convection of the coolant in the hydraulic circuit of collectors.Design technique. A fullscale experimental study concerns the negative effect of natural convection at night in the experimental industrial hybrid solar hot water system in the developed hard and software with remote access.Results. The pilot industrial hybrid solar system with the improved hydraulic circuit and a soft and hardware system for dispatching and managing energy consumption with remote access was developed, built and tested for Northern territories.Practical implications. The hydraulic circuit of collectors equipped with a controller for switching off the coolant provides the northern conditions to increase the thermal energy in storage tanks and the solar fraction of hot water systems, reduce the fuel consumption in additional system sources and the emission of harmful substances produced by the fuel combustion.Originality/value. It is shown that the use of a solenoid valve to eliminate the natural convection increases the thermal energy storage in tanks by at least 50 % and the solar fraction of systems by at least 20 %.

The article discusses the course and results of experimental work on the initial study of the possibility of using one of the varieties of additive technologies – the method of layer-by-layer selective laser melting (SLM) in the manufacture of elements of heat exchangers and hydraulic circuits of spacecraft. Traditional manufacturing techniques for hydro-control elements and spacecraft heat exchangers are based on machining and high-temperature vacuum soldering, leading to a long cycle and high manufacturing costs. As an alternative, the method of layer-by-layer selective laser melting can be considered as a manufacturing method using a three-dimensional model of the product and not requiring additional equipment. This method is based on sequential layer-by-layer fusion of a metal powder with previous fused product layers under the action of a laser beam forming a local region of liquid melt. The article describes experimental work to assess the possibility of using the selective laser melting method. Assessed weld-ability of a sample made by selective laser fusion technology with tips made by traditional technology. Directions for testing the method of selective laser sintering on real structures of heat exchanging units of spacecraft have been determined. A technique is proposed and the results of a study of a sample synthesized by selective laser sintering are presented. Based on the results obtained, an analysis is made of the prospects for using this method in the production of elements of hydraulic circuits and heat exchange units of spacecraft.

Active façade systems incorporating solar thermal collectors currently offer very promising energetic solutions. From among the available systems, a simple solution is the unglazed heat collector for potential integration in low-temperature applications. However, when adopting system definitions, the modification of some design parameters and their impact has to be fully understood. In this study, the case of an unglazed collector integrated into a sandwich panel is assessed and a specific analysis is performed for a proper assessment of the influence of key design parameters. Based on that case study of the real built system, a CFD model is developed and validated and a parametric assessment is then performed, by altering the configurations of both the panel and the hydraulic circuit. In this way, the potential of each measure to harness solar energy can be evaluated and each parameter with its different level of impact can be highlighted, to identify those of higher relevance. A characterization of the real solution completes the study, by providing the efficiency curves and the total energy collected during the experimental campaign. The maximum estimate of the efficiency of a 6 m2 façade was within a range between 0.47 and 0.34 and the heat loss factor was between 4.8 and 7.5. The case study exercises reveal the real energy efficiency and solar production patterns. There was also an opportunity to consider significant improvements to increase the output of the active façade. The main conclusions concerned the different criteria that improved the definition of the system and greater comprehension of alternative designs that may be integrated in the underlying concept. The authors are grateful to the Basque Government for fundingthis research through projects IT781-13 and IT1314-19 and to allthose involved in the different stages for their guidance andinvaluable help.The authors would also like to thank all those companies andresearchers participating in the BASSE project for their stronginvolvement during that research. Results from BASSE project haveinspired present research. The BASSE project received funding fromthe European Union, RFCS Program, Research Fund for Coal and Steel project Building Active Steel Skin (BASSE, Grant Agreement noRFSR-CT-2013-00026)

Today’s automotive industry faces challenges in reducing emissions to comply with ever tightening statutory provisions. The future is set to provide cleaner vehicles which, on the one hand, reduce the required energy consumption while on the other hand are fit to fulfill customer preferences with regard to driving performance. As a result, the design and control of automotive components in the drive train are reconsidered. This paper treats the modeling and parameter identification of a hydraulic circuit for clutch actuation in automatic transmissions (AT) or dedicated hybrid transmissions (DHT). The examined hydraulic servo-system’s function is to provide the necessary pressure and volume flow for clutch actuation without usage of a hydraulic accumulator. Physical modeling and parameter identification is executed using testbed measurements of an according prototype hardware, aiming to contribute in finding a way towards destruction free identification of hydraulic systems. The nonlinear identification for the examined system that shows switching behaviour is performed using the derivation free particle swarm optimization (PSO) method. The physical models are developed for the purpose of being employed for the design of a trajectory tracking nonlinear model-based control scheme for clutch actuation based on the concept of input-output linearization.

Electric motors offer the possibility to control the braking torque in a more precise way than the hydraulic circuit. The applied torque is in fact measured and so it can be used to feedback the co...

By simulating the operating conditions, it is possible to verify and evaluate the technical properties of motor vehicle oil filters and the functionality of the designed equipment. Contaminated engine oil from operation was used with MANN W950/26 oil filter and a CNH Industrial 2992242 oil filter in the test circuit. Before use, the level of engine oil contamination in the test circuit was determined by evaluating the physicochemical properties. The laboratory test equipment also allows monitoring the technical life of oil filters, with variously contaminated engine oil, with the possibility of extending engine oil change service intervals depending on changes in the physicochemical properties of engine oil and filter efficiency. These laboratory tests can be performed in parallel in two hydraulic circuits, which can significantly reduce the testing time of the filter capabilities of oil filters, without the risk of engine damage, provided that the tests were performed under operating conditions. The results of the evaluation of the filtration capacity of oil filters can be used in the design of new filter materials, but also with a suitably determined methodology of oil filter replacement and engine oil change interval, it is possible to extend replacement intervals, which has a significant benefit not only from an economic but also ecological point of view. The result of the measurements is the confirmation of the functionality of the device with the possibility of simulating the operating conditions, at different degrees of oil contamination, at different operating temperatures and using different oil filters.

The paper deals with the control of the test rig for measurement of the stiffness of the spring. The test rig is equipped with integrated hydraulic actuator and multilayer control system with computer vision to automate the testing process and to increase the safety of the operating staff during the testing. The integrated hydraulic actuator allows to control the piston velocity and position and to produce the force needed for the spring compression and stiffness measurement. It has an integrated manifold with four proportional flow control valves connected as the full hydraulic resistance bridge. Each control valve is controlled separately using the input signal. That makes it possible to realize different connections and control strategies of the hydraulic cylinder using the different control algorithms. The hydraulic circuit was modelled and simulated, and the achieved simulation results are presented in the paper. The test rig is controlled using the microprocessor control system and is it equipped by different transducers – position transducer, pressure transducers and force transducer to be able to collect data important for the stiffness characteristic evaluation. The upper level of the control system is created by the vision control system. The goal of the implementation of the machine vision is to decrease the number of the manual operations done by the technician by the spring testing and to extend the automatic testing cycle of the automatic computer vision-controlled movement of the actuator at the beginning of the testing cycle and finally to increase the safety of the operating staff. The structure and functionality of the designed control system, experimentally obtained results and evaluated stiffness characteristic of the tested spring are presented in the following chapters.

The main aim of the article is to present the design of laboratory test equipment, which is appropriate for monitoring the efficiency of oil filters and the system for evaluating the technical life of engine oils in terms of possible extension of service intervals. The functionality of the designed laboratory test equipment for the filtration of motor oils was verified by a practical experiment with a verification measurement and assessment of the suitability of the hydraulic circuit elements and the designed sensing equipment. The laboratory equipment enables the testing of oil filters with different filtration capacity during simultaneous testing in two separate hydraulic circuits with differently contaminated engine oil, while it enables laboratory measurements to be performed while simulating operating conditions.

The paper presents the CFD model of a load sensing directional control valve. The model was validated experimentally in terms of pressure drop and flow force at different positions of the spool. The spool position was imposed manually by means of a micrometric screw and a load cell was used for measuring the flow force. The CFD model was developed with the CAD-embedded tool FloEFD®. The model has been proved to be very reliable in estimating the pressure drop, moreover quite good results were obtained also in the evaluation of the flow force. The CFD simulations were used to tune the coefficients of a lumped parameter model of the valve, so that such a model can be efficiently used for the simulation of an entire hydraulic circuit. Moreover, the CFD model has been used as design tool for attenuating the detrimental effect of the flow force. In particular, the width of the land upstream of the metering edge has an influence on the resultant force on the spool. If was found that it is possible to significantly reduce the flow force at maximum opening with a relatively small increment of the pressure drop across the valve.

Research on the core technology has obtained a patent for invention authorization of hydraulic controlled vibration damper with vibration energy absorption. The hydraulic cylinder structure is designed by the principle of liquid incompressibility. The hydraulic circuit increases and the gap distance changes due to the movement of balance plate under the pressure difference between the two chambers of the hydraulic cylinder. With the damping effect and pressure drop of liquid flow, the purpose of efficient vibration reduction is achieved by absorbing the vibration energy into heat. The invention patent of the self-tuning hydraulic vibration energy absorption is suitable for the situations with high speed, precision, light load and small and medium energy level. For example, the measurement accuracy is improved by vibration reduction with dynamic weighing in instrument. And the processing precision is achieved by vibration reduction for precision machine tools. The invention patent of high power hydraulic emergency energy absorption for multistory parking area is applicable to the conditions with high altitude fall, impact, collision and large-scale energy absorption, such as elevator emergency energy absorption safety devices, the bases of forging press machine tools, high-speed rail locomotive vehicle chassis, and so on.

The paper introduces a hydraulic circuit diagram that controls the anchoring of timber tractor complex when it works on forest land with a steep slope. The paper also presents some research results that simulate the main stages of timber transport technology. The hydraulic anchoring system is supplemented by hydraulic components that help the tractor complex (TC) lift and unload wood, support the departure of moving uphill, gather and load wood at the stops on the slope by accumulated energy. The research results show that if we calculate, determine the size and appropriately arrange the stages, the system only needs to use the accumulated energy in the accumulator after moving downhill, contributing to reducing energy costs for timber transport technology.

The paper deals with the control of the test rig for measurement of the stiffness of the spring. The test rig is equipped with the integrated hydraulic actuator which allows to control the piston velocity and position and to produce the force needed for the spring compression and stiffness measurement. The integrated hydraulic actuator was developed at the department, it and has an integrated manifold with four proportional flow control valves connected as the full hydraulic resistance bridge. Each control valve is controlled separately using the input signal. That makes it possible to realize different connections and control strategies of the hydraulic cylinder using the different control algorithms. The hydraulic circuit was modelled and simulated, and the achieved simulation results are presented in the paper. The test rig is controlled using the microprocessor control system and is equipped by different transducers – position transducer, pressure transducers, force transducer to be able to collect data important for the stiffness characteristic evaluation. The experimentally obtained results and evaluated stiffness characteristic of the tested spring are presented in the following chapters.

The characteristics of a hydraulic directional control method for the displacement controlled system are studied. The directional control is realized by the pilot-operated check valve. The reversing operation of the pilot-operated check valve system is investigated with simulation and experiment. The relationship between the valve spool motion and the circuit pressure has been analyzed during the directional control. The pressure reversing points during the directional control can be used to determine the operation state of the pilot-operated check valve system. The results indicate that the valve spool motion can be confirmed by the pressure reversing points. The response becomes faster with a smaller diameter control piston. A smaller hydraulic chamber volume is also an effective method to improve the dynamic response. Higher circuit pressures decrease the dynamic response. The results can be applied for the optimized design of the hydraulic directional control method with the pilot-operated check valve.

Three filtration systems using the tractor hydraulic circuit were proposed and verified during the tractors operation. Using the tractor-implement hydraulic system and filter body with accessories the universally useful filtration systems were designed. The designed filtration systems are the second stage of universal oil filtration whereas the first stage is the standard tractor filter. The decrease in the content of iron reached the values 25.53 %, 32.95 % and 41.55 % and the average decrease in oil contamination characterized by average value of decrease in content of iron, copper and silicium reached values 24.3 %, 24.7 % and 35.53 % in dependence on the filtration system and an oil contamination level. The decrease in contamination level verified the ability of designed filtration systems for agricultural tractors.

This paper describes a 4-cylinder hydraulic circuit system controlled by a new cross-coupled fuzzy PID, and its leveling algorithm is designed to meet the demand of the loading system for test bed. In order to enable synchronous loading and implement precise leveling control, the output displacement derived from a theoretical model, called Żn, is tracked in real-time. Using AMEsim software, the reliability of the scheme designed by master-slave control and fuzzy PID cross coupling control have been confirmed, and have drawn a conclusion that the more serious the inconsistencies of the load for 4-cylinder are, the more size corresponding synchronization errors will be. Further, leveling experiments have demonstrated that the synchronization performance of leveling system can be improved significantly by adjusting the load values for the 4-cylinder so as to meet the demand of its un-synchronization.

The hydraulic system is the control center of aircraft, the performance of which is critically dependent on the purity of the oil that flows through it. Contamination of hydraulic system oil has been known to be the primary cause of catastrophic failure and accidents. A review of literature in the area of hydraulic oil contamination reveals three facts: (i) there is a dearth of effective methods to prevent intrusion of external contaminants into the hydraulic oil, (ii) there are no effective purification methods for liquid and gaseous contaminants of oil, and (iii) there is an absence of real-time monitoring for major contaminants. This work systematically reviews the hazards, sources, and removal methods of major contaminants, especially of gaseous contaminants. An active method to control oil contamination is proposed instead of the existing passive maintenance techniques that are ridden with problems. In a case study of aviation hydraulic system, our active control system comprises (i) a closed hydraulic circuit and a closed oil tank to prevent the intrusion of external contaminants, (ii) a vacuum centrifuge to efficiently remove contaminants without creating consumption costs, and (iii) monitoring devices installed to actively monitor the contaminant content in oil during operation. The results from the purification experiments and three-dimensional modeling indicate that the active control of hydraulic oil contamination can effectively remove 98.4% solid contaminants and reduce the water content below 50 ppm, and in particular reduce the gas content below 2%. It is obvious that this method can improve the continuous operation capability of aviation hydraulic systems and extend the intermaintenance period of aircrafts by reducing the contaminant content in oil.

This paper presents the procedure used to design a so-called virtual sensor (VS) that is able to estimate fluid flow rates (FRs) in the elements of a complex hydraulic closed network, only knowing the total FR imposed by the circulator pump and the open/closed state of the valves that section off each subnet. The VS is based on a mathematical model representing the relationship between FR and head loss (HL). An identification procedure is developed to estimate the numerical values of the parameters of the FR/HL relationship. Once the mathematical model is completely known, in terms of its topological representation and the numerical values of all the model parameters, a flow-solver algorithm is used to estimate the FR in each branch of the hydraulic circuit. The importance of such a mathematical device is evidenced by the necessity to compute the heating power, directly depending on the hydraulic FR, that each single heating body releases, in order to give a new solution going beyond the current technologies to many problems, such as, for example, the optimization of the central heat generator efficiency or the fair cost allocation in the management of old centralized heating plants. The good results obtained from different tests, carried on a reference mock-up, are presented to prove the reliability and the efficiency of the proposed approach.

Objectives The aim of the study is to generalise the results of the application of technologies and means for organising pulse coolant flow within a district heating system in order to increase its energy efficiency based on the organisation of local hydraulic shocks and the subsequent use of their energy to ensure the purification of heat energy equipment, intensify the heat transfer process and realise the possibility of transforming the available head from one hydraulic circuit to another. Methods Substations connecting the thermal power installations of consumers with heat networks via dependent and independent schemes are analytically generalised. The use of pulse coolant circulation is proposed as a means of overcoming identified shortcomings. Results Principal schemes of substations with pulse coolant circulation for dependent and independent connection of thermal power installations are detailed. A detailed description of their operation is given. The advantages of using pulse coolant circulation in substations are shown. The materials reflecting the results of the technical implementation and practical introduction of this technology are presented. Conclusion Theoretical analysis of the operation of the basic schemes of substations with pulse coolant circulation and the results of their practical application, as well as the materials of scientific works devoted to the use of the energy of a hydraulic impact and the study of the effect of pulse coolant flow on thermal and hydrodynamic processes, have yielded a combination of factors reflecting technical and economic rationality of application of pulse coolant circulation.

The problem of finding optimal parameters of a heat-supply system (HSS) is in ensuring the required throughput capacity of a heat network by determining pipeline diameters and characteristics and location of pumping stations. Effective methods for solving this problem, i.e., the method of stepwise optimization based on the concept of dynamic programming and the method of multicircuit optimization, were proposed in the context of the hydraulic circuit theory developed at Melentiev Energy Systems Institute (Siberian Branch, Russian Academy of Sciences). These methods enable us to determine optimal parameters of various types of piping systems due to flexible adaptability of the calculation procedure to intricate nonlinear mathematical models describing features of used equipment items and methods of their construction and operation. The new and most significant results achieved in developing methodological support and software for finding optimal parameters of complex heat supply systems are presented: a new procedure for solving the problem based on multilevel decomposition of a heat network model that makes it possible to proceed from the initial problem to a set of interrelated, less cumbersome subproblems with reduced dimensionality; a new algorithm implementing the method of multicircuit optimization and focused on the calculation of a hierarchical model of a heat supply system; the SOSNA software system for determining optimum parameters of intricate heat-supply systems and implementing the developed methodological foundation. The proposed procedure and algorithm enable us to solve engineering problems of finding the optimal parameters of multicircuit heat supply systems having large (real) dimensionality, and are applied in solving urgent problems related to the optimal development and reconstruction of these systems. The developed methodological foundation and software can be used for designing heat supply systems in the Central and the Admiralty regions in St. Petersburg, the city of Bratsk, and the Magistral’nyi settlement.

The double-articulated scissors wrecker device was taken as the research object, and its motion analysis and mechanical analysis are performed. The dynamics property of scissors wrecker device was analyzed using by ADAMS software. The influence of the control function for the dynamic property was studied, and the optimum project of control function was acquired. The methods and conclusions are available for designers of scissors wrecker device and hydraulic circuit.

The needing of creating the homogeneous emulsions for obtaining accurate, reproducible results of studies of the water content in the oil products is grounded in the paper. The experimental stand was described in the paper. The central unit of the stand was previously manufactured measurer. The stand was a closed hydraulic circuit containing four zones. Experimental studies were implemented on two types of petroleum products, which confirmed the previously developed theoretical principles. A method for determining the water content in an emulsion containing a previously unknown type of oil product is proposed. Measures have been developed for automated accounting and minimizing the influence of destabilizing factors on the measurement process.

In this paper, a new full-scale indoor ballasted ballast bed cyclic loading test-bed is introduced. Based on the actual operation of high-speed train, the corresponding relationship between the simulation parameters of loading process and the actual operation parameters is analyzed, and the hydraulic transmission and control system of the cyclic loading test-bed, which can simulate the actual operation of vehicles are designed. According to the simulated parameters and test methods of the cyclic loading test bench, the hydraulic circuit is built, and the electro-hydraulic proportional key technology is used to precisely control the hydraulic circuit. The principle and characteristics of the hydraulic system of the test-bed are emphatically expounded, and the performance of the test model is verified by comparing the test results.

In order to solve the sticking for the drilling rig underground coal mine, an electro-hydraulic system is proposed. Firstly, the structure of the drilling rig is introduced. Based on the structure and working principle of the drilling rig, an anti-sticking model is built. Besides, the hydraulic circuit of the drilling rig is designed. The model of the swing circuit and the feed circuit is built with AMESim. Furthermore, the simulation is performed according to the parameters of the drilling rig and the experience. The simulation results show that the anti-sticking system is effective and meets the design requirements.

Nowadays, sacrificing animals to develop medical devices and receive regulatory approval has become more common, which increases ethical concerns. Although in vivo tests are necessary for development and evaluation of new devices, nonetheless, with appropriate in vitro setups and mathematical models, a part of the validation process can be performed using these models to reduce the number of sacrificed animals. The main aim of this study is to present a mathematical model simulating the hydrodynamic function of a rotary blood pump (RBP) in a pulsatile in vitro flow environment. This model relates the pressure head of the RBP to the flow rate, rotational speed, and time derivatives of flow rate and rotational speed. To identify the model parameters, an in vitro setup was constructed consisting of a piston pump, a compliance chamber, a throttle, a buffer reservoir, and the CentriMag RBP. A 40% glycerin–water mixture as a blood analog fluid and deionized water were used in the hydraulic circuit to investigate the effect of viscosity and density of the working fluid on the model parameters. First, model variables were physically measured and digitally acquired. Second, an identification algorithm based on regression analysis was used to derive the model parameters. Third, the completed model was validated with a totally different set of in vitro data. The model is usable for both mathematical simulations of the interaction between the pump and heart and indirect pressure measurement in a clinical context.

Throttling and fluid compressibility losses are the major losses which occur during the valve transition in a switched mode hydraulic circuit. To minimize the throttling energy loss, a soft switch concept with lock and release mechanism was introduced by different researchers. In the literature, two different kinds of soft switches, one locking and another passive, were introduced in a hydraulic circuit. Thereafter, experimental validation was reported considering only a locking-type soft switch. But the influence of the passive soft switch on the performance of the hydraulic system was not reported. In this article, how the passive soft switch would affect the system efficiency has been investigated through bond graph model simulation. It has been shown both numerically and experimentally by other researchers that the use of a passive soft switch and a locking mechanism, depending upon configuration, can lead to more than 66.1% reduction in throttling energy loss. In this article, it has been further shown that an additional 3.25% throttling energy is saved when the passive soft switch is discarded from the system and only the locking mechanism is retained. The critical parameters of the locking soft switch have been optimized through multi-run simulation and, thereafter, a relationship between the critical parameters of the locking soft switch and the throttling energy loss of the valve has been obtained by using multiple regression analysis. Also, the variations of energy losses with respect to different valve orifice areas, duty cycles, and pulse width modulation frequencies are investigated through simulation.

This paper presents the characterization of the hydraulic suspension system of Special Purpose Trailer which is a modular semi-trailer used for carrying heavy commercial equipment’s and heavy cargos. Presently automotive industry is using the knuckle joint hydraulic suspension system for the above mentioned trailer. The study includes the characterization of the hydraulic spring of the system based on the polytropic process and mathematical modelling of the quarter car hydraulic suspension system in MATLAB/SIMULINK. Basically the hydraulic suspension system consists of a hydraulic cylinder ram, pressurized hydraulic circuit, cut off valves, accumulator, and axel-wheel assembly. The study mainly concentrates on the accumulator pressure values as changing the pressure of accumulator directly affects the behavior of suspension system. MATLAB/SIMULINK software is used for obtaining the behavioral pattern of the suspension system on account of different accumulator pressure values. And finally the best possible value of accumulator pressure is obtained under the working conditions of the trailer.

This paper focuses on the calculations of basic variables of the hydrostatic circuits in the mechatronic systems. These calculations are important for machines used for forming materials by means of great forces, e.g. hydraulic press. Due to differences in equipment design, lack of a universal method of calculation is noticeable. It is necessary to determine the coefficients required for the calculations in an experimental way.

Injection systems represent key elements in modern diesel engines because of the fundamental role played in fuel spray formation and evolution during the combustion phase. For this reason, their design needs attention and continuous improvements in order to satisfy environmental standards and consumer demands. The present work illustrates the main phases that form the basis of an activity of hydraulic characterization of a solenoid injector for diesel engine applications. The performance of the injection system has been verified by means of injected flow-rate time histories, fuel injected quantities, leakages through the injector pilot-valve, electric driving signals and pressure transients, for different operating conditions, which refer to single and multiple injections. Furthermore, a complete numerical model of the injector and of the high-pressure hydraulic circuit of the injection apparatus has been developed with the aim of deepening the understanding of the internal dynamics of the injection system, which could not be analyzed only experimentally.

Hydraulic turbines are operating at part load conditions depending on availability of hydraulic energy or to meet the grid requirements. The turbine experiences more fatigue during the part load operating conditions due to flow phenomena such as vortex breakdown in the draft tube and flow instability in the runner. The present paper focuses on the investigation of a high head model Francis turbine operating at 50% load. Pressure measurements have been carried out experimentally on a model Francis turbine. Total six pressure sensors were mounted inside the turbine and other two pressure sensors were mounted at the turbine inlet pipe. It is observed that the turbine experiences significant pressure fluctuations at the vaneless space and the runner. Moreover, a standing wave is observed between the pressure tank outlet and the turbine inlet. Analysis of the data acquired by the pressure sensors mounted in the draft tube showed the presence of vortex breakdown co-rotating with the runner. The detailed analysis showed the rotating and plunging components of the vortex breakdown. The influence of the rotating component was observed in the entire hydraulic circuit including distributor and turbine inlet but not the plunging one.

This paper presents the experimental validation of a new methodology for the design of the spool surfaces of four way three position direct operated proportional directional valves. The proposed methodology is based on the re-design of both the compensation profile (the central conical surface of the spool) and the lateral surfaces of the spool, in order to reduce the flow forces acting on the spool and hence the actuation forces. The aim of this work is to extend the application range of these valves to higher values of pressure and flow rate, thus avoiding the employment of more expensive two stage configurations in the case of high-pressure conditions and/or flow rate. The paper first presents a theoretical approach and a general strategy for the sliding spool design to be applied to any four way three position direct operated proportional directional valve. Then, the proposed approach is experimentally validated on a commercially available valve using a hydraulic circuit capable of measuring the flow rate as well as the actuation force over the entire spool stroke. The experimental results, performed using both the electronic driver provided by the manufacturer and a manual actuation system, show that the novel spool surface requires remarkably lower actuation forces compared to the commercial configuration, while maintaining the same flow rate trend as a function of the spool position.

HydraROPS can be installed on tractors equipped with certified ROPS.The deployment time of HydraROPS is 0.743s.After a rollover situation the system sends GPS coordinates to emergency call centre.The cost to install HydraROPS in a marketable tractor model is 2176?. An inadequate use of the deployable Roll Over Protective Structure (ROPS) in agricultural tractors contributes to fatalities in rollover events. To help to resolve this problem, an automatically deployable ROPS was designed, constructed and tested. The prototype, called HydraROPS, established two assistance levels for the elevation of the foldable ROPS. In the first level, the driver decides to change the ROPS' position and this change is made using the manual activation on the board. In the second level, an automatic change to the operative position occurs in situations of impending rollover, without the intervention of the driver. In this level, it automatically sends a phone message with the GPS location to contact emergency response personnel. The tractor's hydraulic power was used to move the protective structure. In order to increase the deployment speed of ROPS, a pressure accumulator was included in the hydraulic circuit. The deployment time of the ROPS without the pressure accumulator was 2.599s and with the pressure accumulator 0.743s. The results of the research show that the pressure accumulator assembled in the hydraulic circuit reduced the deployment time of ROPS by 71%; and that the electronic control system can correctly predict overturn. HydraROPS has the advantage compared to other automatic deployment devices of protective structures that can be installed on tractors equipped with a certified rollover protective structure. The installation in marketable tractor models does not modify the protection structure; therefore a new certification of the protection structure is not necessary.

Most automatic steering systems for large tractors are designed with hydraulic systems that run on either constant flow or constant pressure. Such designs are limited in adaptability and applicability. Moreover, their control valves can unload in the neutral position and eventually lead to serious hydraulic leakage over long operation periods. In response to the problems noted above, a multifunctional automatic hydraulic steering circuit is presented. The system design is composed of a 5-way-3- position proportional directional valve, two pilot-controlled check valves, a pressure-compensated directional valve, a pressurecompensated flow regulator valve, a load shuttle valve, and a check valve, among other components. It is adaptable to most open-center systems with constant flow supply and closed-center systems with load feedback. The design maintains the lowest pressure under load feedback and stays at the neutral position during unloading, thus meeting the requirements for steering. The steering controller is based on proportional-integral-derivative (PID) running on a 51-microcontroller-unit master control chip. An experimental platform is developed to establish the basic characteristics of the system subject to stepwise inputs and sinusoidal tracking. Test results show that the system design demonstrates excellent control accuracy, fast response, and negligible leak during long operation periods.

In this paper, a novel concept for stabilising a hydraulic system containing a counterbalance valve and a pressure compensated flow supply is presented. The concept utilizes a secondary circuit where a low-pass filtered value of the load pressure is generated and fed back to the compensator of the flow supply valve. The novel concept has been investigated theoretically and experimentally. A linear model has been developed to verify the improved stability conditions. The novel concept has been implemented on a single boom actuated by a cylinder. The results show that the pressure oscillations in an otherwise unstable system can be suppressed with the novel concept. This happens without any compromise on the load independence of the flow supply but with some limitations on response time.

Purpose. Search for ways to improve the technical level of the hydraulic fluid power of a hose concrete pump by analyzing the hydraulic schematic diagram and dynamic characteristics depending on the moment of resistance, moment of inertia and properties of the working fluid. Method. The construction of a mathematical model of the dynamics of a hydraulic fluid power is based on Newton's laws of mechanics, Pascal's law and the continuity equation for fluids. The dynamics study was implemented using the VisSim package. The results of studies of the influence of variable parameters on the rotor speed and pressure in the discharge line of the hydraulic motor are presented in graphical form. Results. It was found that in a volumetric hydraulic fluid power of a concrete pump with rotor rotation from a gerotor hydraulic motor, there are significant fluctuations in pressure and speed, due to the kinematics of the pump, temporary factors of the increase in the moment of resistance and supply of the working fluid to the hydraulic motor with the throttle method of its regulation. The ratio of the maximum and steady-state pressure values is 1,9 times obtained for hydraulic motors of different displacement. The possibilities of reducing the dynamic loading of the hydraulic fluid power by improving its hydraulic schematic diagram and control algorithm are shown. Conclusion. Recommendations have been developed for reducing dynamic loads in a hydraulic fluid power by modernizing the hydraulic circuit diagram by introducing electrohydroautomatics devices and changing the algorithm for starting and stopping the pump.

The key point of a single-shaft parallel hybrid electric vehicle is the ability to start the engine while propelling the vehicle by utilizing a single traction motor. To pursue better driving comfort, an accurate engine-start process should be designed. For the purpose of smoothly starting the engine, this paper proposes a seven-phase engine-start control strategy with the assistance of the slipping status of the separating clutch and shifting clutch. A detailed drivetrain model of a single-shaft parallel hybrid electric vehicle is established to support the designed control strategy with consideration of the dynamic characteristics of the engine, motor and clutch. With the support of the hydraulic circuit established in this paper, feedforward-feedback controller based on proportional-integral ( PI ) algorithm is developed to track the demanded pressure for separating clutch. Simulation and test results validate that the proposed engine-start control strategy is feasible and effective for improving driving comfort and ensuring the drivability of the target vehicle. The key design parameters of the control strategy are optimized for the minimal equivalent fuel consumption. Test results indicate that the designed control strategy can effectively improve the fuel economy of engine-start control process compared with conventional strategy.

The check valves play an important role in safety and reliability of many technologies using liquid or gas flow. Check valves are elements of the hydraulic system enabling the one-way flow without a significant pressure loss and preventing the reverse flow. The ideal check valve should have an acceptable pressure loss and, when closed, there should be no undesirable dynamic phenomena like water hammer or slam. The static properties describe energy losses of the check valve, and the producers provide them as a standard. The static properties can be defined either in an experimental way or using the CFD analysis. The dynamic properties of the check valve express a relation between the maximum reverse velocity and water column deceleration. Unfortunately, the definition of dynamic properties can be obtained only experimentally, and for small pipe diameters. It is very demanding, time consuming and expensive to define the dynamic characteristic so it is why the producers do not offer it as a standard. The article deals with static and dynamic properties of different check valves with different closing principles. There was built a testing hydraulic circuit with the pipe diameter DN 100, that enables the simulation of check valve slam during the flow reversing. The attention was paid to the definition of flow deceleration, which is rather problematic and usually defined in a different way for each lab. Zpětná klapka hraje důležitou roli v bezpečnosti a spolehlivosti mnoha technologií, ve kterých dochází k proudění tekutiny. Zpětné klapky jsou prvky umožňující proudění jedním směrem bez významných tlakových ztrát a zabraňují zpětnému toku. Ideální zpětná klapka by měla mít přijatelnou tlakovou ztrátu a neměla by vyvolávat nechtěné dynamické jevy (např. vodní ráz) při uzavření. Statická charakteristika popisuje energetické ztráty klapky a výrobci ji standardně dodávají. Charakteristika může být stanovena na základě fyzického měření nebo pomocí CFD simulace. Dynamická charakteristika zpětné klapky popisuje vztah mezi maximální rychlostí zpětného proudění a zpomalením vodního sloupce. Bohužel, dynamická charakteristika může být stanovena pouze experimentálně u prvků malých světlostí. Výrobci dynamickou charakteristiku běžně nedodávají, protože měření je velmi náročné a nákladné. Ve článku jsou uvedeny statické a dynamické charakteristiky různých zpětných armatur s různými principy zavírání. Byla postavena trať pro testovaní dynamických vlastností těchto armatur o světlosti DN 100. Pozornost byla věnována i definici zpomalení proudění, která je problematická a každá laboratoř má vlastní definici.

This study, an additional electro hydraulic circuit was designed and assembled to a conventional hydraulic steering circuit of a small farm tractor (Kubota L4708). The proposed hydraulic circuit is able to connect with a microcontroller which was programmed to command the steering system by using a pre-calculation path way. It is not only flexible to merge with a GPS or a visual navigation module but the system also has a manual/auto mode, easy for replacement and maintenance. The design that is suitable for farming comprises of a 4/3 electro hydraulic proportional valve with infinite position as a main steering actuator. The proportional valve allows the left/right position and velocity control of the front wheels while pressure in the system can be adjusted by proportional feature of the valve and a separated PID control loop via an identified system transfer function.

By studying the research status of domestic and overseas, formulated the overall plan of the target spray control system of self-propelled target sprayer. Based on according to the speed to dynamically adjust the sampling frequency by single chip microcomputer controller to realization of three consecutive sampling method for identifying targets and the algorithm of interference signal filtering, using solenoid valve to control the spray opening and closing, combining with technology of target based on laser sensor. In this paper, we selected of main components of the hydraulic circuit. And we used STCI2CSA60S2 as the core to design the connection of single chip processor module, signal detection module, matrix key module, liquid crystal display module, alarm indicator module and serial interface communication module. Based on the C language to write the handler and target discrimination algorithm, including the processing of the main program, the target sampling, detection and alarm indication and matrix button subroutine.

Monitoring is an important aspect of operation and maintenance in virtually every industrial system. However, the extent and methods of monitoring vastly vary in different systems, from fully automated to fully manual. One of the challenges of automated monitoring is the tediousness of, and the extent of engineering time and effort required to develop necessary models or machine learning algorithms for the units to be monitored. Model-free monitoring, on the other hand, can save resources and efforts substantially. However, more often than not they have a very limited scope and application. Such a system is needed, for example, to monitor entire Heating, Ventilation and Air Conditioning (HVAC) systems, consisting of different types of sensors such as temperature, pressure, humidity or flow sensors. Recently, we proposed the Context-Aware Health Monitoring (CAH) system for model-free monitoring of any injective-function black-box, and it was tested successfully on an AC motor. In this paper, we evaluate the CAH system for an entirely different industrial use-case, that is, a hydraulic circuit. The results show the potential for considerable benefits in monitoring HVAC systems. Moreover, in the light of applying CAH to different use-cases which may potentially need a different setup of parameters, we performed a sensitivity analysis on the values of different parameters in the system. The results show the robustness of CAH with regard to the values of these parameters.

Purpose – The purpose of this paper is to evaluate the performance of the semi-active fluid damper. It is recognized that the performance of such a damper depends upon the magnetic and hydraulic circuit design. These dampers are generally used to control the vibrations in various applications in machine tools and robots. The present paper deals with the design of magneto-rheological (MR) damper. A finite element model is built to analyze and understand the performance of a 2D axi-symmetric MR damper. Various configurations of damper with modified piston ends are investigated. The input current to the coil and the piston velocity are varied to evaluate the resulting change in magnetic flux density (B), magnetic field (H), field dependent yield stress and magnetic force vectors. The simulation results of the various configurations of damper show that higher magnetic force is associated with plain piston ends. The performance of filleted piston ends is superior to that of other configurations for the same magnitude of coil current and piston velocity. Design/methodology/approach – The damper design is done based on the fact that mechanical energy required for yielding of MR fluid increases with increase in applied magnetic field intensity. In the presence of magnetic field, the MR fluid follows Bingham’s plastic flow model, given by the equation τ = η γ•+τ y (H) τ > τ y . The above equation is used to design a device which works on the basis of MR fluid. The total pressure drop in the damper is evaluated by summing the viscous component and yield stress component which is approximated as ΔP = 12ηQL/g3W + CτyL/g, where the value of the parameter, C ranges from a minimum of 2 (for ΔPτ ΔPη less than approximately 1) to a maximum of 3 (for ΔPτ/ΔPη greater than approximately 100). To calculate the change in pressure on either side of the piston within the cylinder, yield stress is required which is obtained from the graph of yield stress vs magnetic field intensity provided by Lord Corporation for MR fluid −132 DG. Findings – In this work, three different finite element models of MR damper piston are analyzed. The regression equations, contour plots and surface plots are obtained for different parameters. This study can be used as a reference for selecting the parameters for meeting different requirements. It is observed from the simulation of these models that the plain ends model gave optimum magnetic force and 2D flux lines with respect to damper input current. This is due to the fact that the plain ends model has more area when compared with that of other models. It is also observed that filleted ends model gave optimum magnetic flux density and yield stress. As there is reduced pole length in the filleted ends model, the MR fluid occupies vacant area, and hence results in increased flux density and yield shear stress. The filleted ends assist the formation of dense magnetic flux lines thereby increasing the flux density and yield stress. This implies that higher load can be carried by the filleted ends damper even with a smaller size. Originality/value – This work is carried out to manufacture different capacities of the dampers. This can be applied as vibration controls.

The article presents the results of development and experimental studies of artificial ventricles used for modeling the cardiovascular system. The ventricle is divided into two hemispheres separated by a membrane, ensuring the necessary level of contractility of the artificial ventricle and separating its hydraulic and pneumatic components. The study considered two versions of the ventricle, with mechanical check valves (Vesta Trading, Shcherbinka, Moscow, Russia) and bicuspid artificial valves (ZAO NPP MedEng, Penza, Russia) as aortic and mitral valves. The designed ventricles were compared with a reference, which was represented by a Medos VAD membranous artificial ventricle (Medos Medizintechnik AG, Stolberg, Germany).