Pub Date : 2023-05-03DOI: 10.13052/ijfp1439-9776.2427
Shaoyang Qu, Federico Zappaterra, A. Vacca, Zifan Liu, Enrique Busquets
This paper proposes an electro-hydraulic actuator (EHA) system, and a novel-designed electro-hydraulic unit (EHU) consisting of a fixed-displacement hydraulic gear machine and a variable-speed electric machine. The novel EHU design integrates an electric machine and a hydraulic machine in a single housing, targeting optimal compactness, power density, and component reduction. The EHA system features an open circuit design, where hydraulic hoses connect the EHU with a tank, a valve manifold, and the hydraulic cylinder. In this way, the proposed EHA technology can be used to implement distributed hydraulic actuation in a vehicle without requiring changes to the hydraulic actuators or at the overall layout of the hydraulic components with respect to the original vehicle design. A dedicated test rig is developed to verify the performance of the proposed EHA system. The efficiency of the EHA is measured in a steady state and under a realistic duty cycle of a commercial compact loader. The efficiency of the EHA system based on the measurements on the test rig can reach 54% with up to 20 kN load and 6 kW power level. Furthermore, the EHU is implemented on the reference machine to drive the boom function. Preliminary results on the performance of the EHU show an efficiency of up to 68% under different loading conditions.
{"title":"Experimental Verification of An Electro-Hydraulic Actuation System Driven by An Integrated Electro-Hydraulic Unit","authors":"Shaoyang Qu, Federico Zappaterra, A. Vacca, Zifan Liu, Enrique Busquets","doi":"10.13052/ijfp1439-9776.2427","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2427","url":null,"abstract":"This paper proposes an electro-hydraulic actuator (EHA) system, and a novel-designed electro-hydraulic unit (EHU) consisting of a fixed-displacement hydraulic gear machine and a variable-speed electric machine. The novel EHU design integrates an electric machine and a hydraulic machine in a single housing, targeting optimal compactness, power density, and component reduction. The EHA system features an open circuit design, where hydraulic hoses connect the EHU with a tank, a valve manifold, and the hydraulic cylinder. In this way, the proposed EHA technology can be used to implement distributed hydraulic actuation in a vehicle without requiring changes to the hydraulic actuators or at the overall layout of the hydraulic components with respect to the original vehicle design. A dedicated test rig is developed to verify the performance of the proposed EHA system. The efficiency of the EHA is measured in a steady state and under a realistic duty cycle of a commercial compact loader. The efficiency of the EHA system based on the measurements on the test rig can reach 54% with up to 20 kN load and 6 kW power level. Furthermore, the EHU is implemented on the reference machine to drive the boom function. Preliminary results on the performance of the EHU show an efficiency of up to 68% under different loading conditions.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44286555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-17DOI: 10.13052/ijfp1439-9776.2414
Thomas Ransegnola, A. Vacca
This paper presents a simulation based approach for sizing the axial balance elements of a pressure compensated external gear machine. The reference hydraulic unit must be able to guarantee operation in two quadrants, as either a pump or a motor. It also needs to operate in a wide operating range of speed and pressure, as it is to be used as primary hydraulic unit for an electro-hydraulic actuator (EHA). The design procedure builds upon past work at the author’s center, but it extends it to the case of multiple quadrant units. Also, a unique method for modeling of both mixed lubrication and cavitation that might occur in the lubricating film is used. After describing the design procedure, the paper discusses the features of the balancing of a reference unit, along with the effects of both cavitation and mixed lubrication.
{"title":"Virtual Design and Analysis of the Balancing Element of an External Gear Machine Considering Cavitation and Mixed Lubrication Effects","authors":"Thomas Ransegnola, A. Vacca","doi":"10.13052/ijfp1439-9776.2414","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2414","url":null,"abstract":"This paper presents a simulation based approach for sizing the axial balance elements of a pressure compensated external gear machine. The reference hydraulic unit must be able to guarantee operation in two quadrants, as either a pump or a motor. It also needs to operate in a wide operating range of speed and pressure, as it is to be used as primary hydraulic unit for an electro-hydraulic actuator (EHA). The design procedure builds upon past work at the author’s center, but it extends it to the case of multiple quadrant units. Also, a unique method for modeling of both mixed lubrication and cavitation that might occur in the lubricating film is used. After describing the design procedure, the paper discusses the features of the balancing of a reference unit, along with the effects of both cavitation and mixed lubrication.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44276444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-17DOI: 10.13052/ijfp1439-9776.2413
P. Mäenpää, J. Mattila
This paper discusses the path planning and path-following control for a four wheel drive (4WD), steer-articulated boom lift driven by hydraulic actuators. The environment is assumed to be both static and known. The path planning will be done in two phases, where the first one finds a crude, collision-free path accounting for the vehicle dimensions, and this path will be smoothed with a path smoothing algorithm to satisfy the kinematic and dynamic constraints imposed by the vehicle and its actuators. The path smoothing algorithm will be chosen from several candidates by using a simulated test scenario. Then, the simulation results will be used to verify the path planners feasibility in heavy-duty, four-wheel-steered field robots having hydraulic actuators and high inertia.
{"title":"Path Planning and Smoothing for 4WDs Hydraulic Heavy-Duty Field Robots","authors":"P. Mäenpää, J. Mattila","doi":"10.13052/ijfp1439-9776.2413","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2413","url":null,"abstract":"This paper discusses the path planning and path-following control for a four wheel drive (4WD), steer-articulated boom lift driven by hydraulic actuators. The environment is assumed to be both static and known. The path planning will be done in two phases, where the first one finds a crude, collision-free path accounting for the vehicle dimensions, and this path will be smoothed with a path smoothing algorithm to satisfy the kinematic and dynamic constraints imposed by the vehicle and its actuators. The path smoothing algorithm will be chosen from several candidates by using a simulated test scenario. Then, the simulation results will be used to verify the path planners feasibility in heavy-duty, four-wheel-steered field robots having hydraulic actuators and high inertia.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41557143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-17DOI: 10.13052/ijfp1439-9776.2416
V. Zakharov, T. Minav
Recently the pump-controlled system has actively been proposed as a replacement for conventional valve-controlled systems, to improve the energy efficiency in non-road mobile machinery. Earlier research demonstrated that a pump-controlled hydraulic system combines the best properties of traditional hydraulics and electric intelligence. This pump-controlled system can be realized via direct control of hydraulic pimp/motor by varying speed of electric motor without complex servo valves. Nowadays, a wide range of different electric motors is known and available with efficiency higher than 95% One of the most attractive option of electric motor is Permanent Magnet Synchronous Motor (PMSM) due to its size, power, and high efficiency. However, control of electric motors in pump-controlled systems has are not yet considered and not well researched. In this paper, the main objective of this investigation is determination of control values for the pump-controlled actuator and analysis of system’s behavior in different applications. Therefore, model of PMSM drive with pump-emulated load is proposed. Field Oriented Control (FOC) gives wide range of the speed regulation and smooth characteristics, but tuning of controllers is challenging. Case of the steering-modeled load represented that such operations need more power than other modes. More complex frequency converters allow to reach higher level of accuracy and decrease torque ripples, but complexity of such systems increases rapidly.
{"title":"Analysis of Frequency Adjustable Control of Permanent Magnet Synchronous Motor for Pump-controlled Actuators","authors":"V. Zakharov, T. Minav","doi":"10.13052/ijfp1439-9776.2416","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2416","url":null,"abstract":"Recently the pump-controlled system has actively been proposed as a replacement for conventional valve-controlled systems, to improve the energy efficiency in non-road mobile machinery. Earlier research demonstrated that a pump-controlled hydraulic system combines the best properties of traditional hydraulics and electric intelligence. This pump-controlled system can be realized via direct control of hydraulic pimp/motor by varying speed of electric motor without complex servo valves. Nowadays, a wide range of different electric motors is known and available with efficiency higher than 95% One of the most attractive option of electric motor is Permanent Magnet Synchronous Motor (PMSM) due to its size, power, and high efficiency. \u0000However, control of electric motors in pump-controlled systems has are not yet considered and not well researched. \u0000In this paper, the main objective of this investigation is determination of control values for the pump-controlled actuator and analysis of system’s behavior in different applications. \u0000Therefore, model of PMSM drive with pump-emulated load is proposed. Field Oriented Control (FOC) gives wide range of the speed regulation and smooth characteristics, but tuning of controllers is challenging. \u0000Case of the steering-modeled load represented that such operations need more power than other modes. More complex frequency converters allow to reach higher level of accuracy and decrease torque ripples, but complexity of such systems increases rapidly.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49484131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The high-speed on-off valve is the core component for adjusting the oil pressure of the pressure reducing valve in the clutch shifting system of engineering vehicles, and its response speed is one of the important indicators to measure its performance. In order to improve the dynamic performance of high-speed on-off valve, the electromagnet with solid magnetic isolation structure was designed and simulated by considering the eddy current loss factor. A high-speed on-off valve electromagnetic actuator with high response speed was obtained. Firstly, the theoretical calculation and verification of the theory were carried out by using the electromagnet design theory, and the theoretical model of the electromagnet was built. Secondly, the electromagnet parameter model was brought into the finite element simulation software ANSYS Electronics to simulate and optimize the static magnetic field and the transient magnetic field respectively. The different structural parameters (guide bush thickness, outer magnetic pole thickness, magnetic isolation structure, armature length) were analyzed. And the effect of the coil parameters (number of strands) on the steady-state electromagnetic force and the dynamic displacement of the armature was analyzed. The values of the structural parameters of the electromagnet were subsequently determined. Finally, the static and dynamic characteristics experiment of the magnetically separated solid electromagnet is designed and processed. The experiment and simulation results are in good agreement. The feasibility of the high-resistance electromagnet structure design and the correctness of the simulation are verified. Reasonable optimization of structural parameters and coil parameters has obvious significance for improving the dynamic characteristics of high-speed on-off valve electromagnets.
{"title":"Simulation and Experiment of Electromagnet for High-Speed On-off Valve for Vehicle Shifting System","authors":"Qingjun Yang, Yudong Liu, Rui Zhu, Qinjian Mao, Rizhi Dong, Hongxuan Jiang","doi":"10.13052/ijfp1439-9776.2412","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2412","url":null,"abstract":"The high-speed on-off valve is the core component for adjusting the oil pressure of the pressure reducing valve in the clutch shifting system of engineering vehicles, and its response speed is one of the important indicators to measure its performance. In order to improve the dynamic performance of high-speed on-off valve, the electromagnet with solid magnetic isolation structure was designed and simulated by considering the eddy current loss factor. A high-speed on-off valve electromagnetic actuator with high response speed was obtained. Firstly, the theoretical calculation and verification of the theory were carried out by using the electromagnet design theory, and the theoretical model of the electromagnet was built. Secondly, the electromagnet parameter model was brought into the finite element simulation software ANSYS Electronics to simulate and optimize the static magnetic field and the transient magnetic field respectively. The different structural parameters (guide bush thickness, outer magnetic pole thickness, magnetic isolation structure, armature length) were analyzed. And the effect of the coil parameters (number of strands) on the steady-state electromagnetic force and the dynamic displacement of the armature was analyzed. The values of the structural parameters of the electromagnet were subsequently determined. Finally, the static and dynamic characteristics experiment of the magnetically separated solid electromagnet is designed and processed. The experiment and simulation results are in good agreement. The feasibility of the high-resistance electromagnet structure design and the correctness of the simulation are verified. Reasonable optimization of structural parameters and coil parameters has obvious significance for improving the dynamic characteristics of high-speed on-off valve electromagnets.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49146811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-17DOI: 10.13052/ijfp1439-9776.2415
Antonella Bonavolontà, E. Frosina, P. Marani, Davide Mesturini, Cesare Dolcin, Ulderico Busani
Through a study on the Fluid Power innovations in the last years emerged that still few solutions have been successfully implemented for the optimization of the hydraulic circuits. The recent machine electrification offers a potential for investment in energy-saving hydraulic systems to ensure greater performance and higher battery autonomy. From different studies emerged that in the specific field of ICE Off-road Vehicles, only about 10–15% of the available power at fuel level is actually transformed into useful energy for the actuators. Particularly the losses in the Directional Control Valves represent about 35–40% of the hydraulic energy available at the pump level. The traditional Directional Control Valves design solutions, in fact, neglects important opportunities for reducing losses and improving internal regeneration. Especially, energy recovery is rarely applied and in any case by means of important superstructures which considerably increase the costs of the system. This paper presents a new hydraulic architecture: an original Directional Control Valve layout based on a Downstream Compensation approach. In particular, a Flow Sharing system is implemented in this new architecture with the goal to minimize the wasted energy. In fact, this system realizes an important energy recovery from both the inertial loads and the simultaneous use of multiple actuators at different pressure level. The circuit enables recovered energy to be stored in a high-pressure accumulator. The paper presents the simulation results and the energy saving estimation realized through a lumped parameter environment “Amesim Simcenter”. Additionally, the results of experimental activities show the innovative system performance, benefits and physical applicability. This idea is based on concrete objectives and pays particular attention to cost sustainability, industrial manufacturability and system scalability.
{"title":"Experimental and Modelling Analysis of a Downstream Compensation System: Energy Optimization of the Directional Control Valves","authors":"Antonella Bonavolontà, E. Frosina, P. Marani, Davide Mesturini, Cesare Dolcin, Ulderico Busani","doi":"10.13052/ijfp1439-9776.2415","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2415","url":null,"abstract":"Through a study on the Fluid Power innovations in the last years emerged that still few solutions have been successfully implemented for the optimization of the hydraulic circuits. The recent machine electrification offers a potential for investment in energy-saving hydraulic systems to ensure greater performance and higher battery autonomy. From different studies emerged that in the specific field of ICE Off-road Vehicles, only about 10–15% of the available power at fuel level is actually transformed into useful energy for the actuators. Particularly the losses in the Directional Control Valves represent about 35–40% of the hydraulic energy available at the pump level. The traditional Directional Control Valves design solutions, in fact, neglects important opportunities for reducing losses and improving internal regeneration. Especially, energy recovery is rarely applied and in any case by means of important superstructures which considerably increase the costs of the system. This paper presents a new hydraulic architecture: an original Directional Control Valve layout based on a Downstream Compensation approach. In particular, a Flow Sharing system is implemented in this new architecture with the goal to minimize the wasted energy. In fact, this system realizes an important energy recovery from both the inertial loads and the simultaneous use of multiple actuators at different pressure level. The circuit enables recovered energy to be stored in a high-pressure accumulator. The paper presents the simulation results and the energy saving estimation realized through a lumped parameter environment “Amesim Simcenter”. Additionally, the results of experimental activities show the innovative system performance, benefits and physical applicability. This idea is based on concrete objectives and pays particular attention to cost sustainability, industrial manufacturability and system scalability.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48248226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-17DOI: 10.13052/ijfp1439-9776.2411
M. P. Nostrani, Henrique Raduenz, A. Dell’Amico, Anders Petter Krus, V. Negri
This paper presents a multi-chamber hydraulic actuator controlled by digital pumps and on/off valves, in order to improve the efficiency of hydraulic systems applied in aircraft for flight control. Hydraulic positioning systems are used in many different applications, such as mobile machinery, industry and aerospace. In aircraft, the hydraulic actuators are used at flight control surfaces, cargo doors, steering, landing gear and so one. However, the massive use of resistive control techniques, which throttles the passages of the hydraulic fluid, associated with internal leakage of the hydraulic components, make these systems low energy efficient. In order to improve their energy efficiency, digital hydraulics emerges as a promising solution mainly for mobile applications. In this paper a hydraulic positioning system for aircraft control surfaces using a multi-chamber actuator controlled by on/off valves and a digital pump is proposed. The use of a digital pump with three fixed displacement pumps can provide eight different volumetric displacement outputs. The multi-chamber actuator with four areas can operate in two different modes, normal or regenerative, resulting in six different equivalent areas. The regenerative mode allows the actuator to achieve higher actuation velocity values with smaller pumps. These equivalent areas combined with the different supplied flow rates can deliver 43 different discrete output velocity values for the actuator, in steady-state. For the system dynamic analyses, three mathematical simulation models were developed using MATLAB/Simulink and Hopsan, one for the digital system, and two for the conventional solutions applied in aircraft (Servo Hydraulic Actuators (SHA) and Electro Hydrostatic Actuator (EHA)). The simulation results demonstrate that the digital actuator can achieve, for position control, a maximum position error, in a steady-state, of 0.7 mm. From the energy consumption point of view, the digital circuit consumes 31 times less energy when compared with the SHA and 1.7 when compared to the EHA, resulting in an energy efficiency of 54%.
{"title":"Multi-Chamber Actuator Using Digital Pump for Position and Velocity Control Applied in Aircraft","authors":"M. P. Nostrani, Henrique Raduenz, A. Dell’Amico, Anders Petter Krus, V. Negri","doi":"10.13052/ijfp1439-9776.2411","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2411","url":null,"abstract":"This paper presents a multi-chamber hydraulic actuator controlled by digital pumps and on/off valves, in order to improve the efficiency of hydraulic systems applied in aircraft for flight control. Hydraulic positioning systems are used in many different applications, such as mobile machinery, industry and aerospace. In aircraft, the hydraulic actuators are used at flight control surfaces, cargo doors, steering, landing gear and so one. However, the massive use of resistive control techniques, which throttles the passages of the hydraulic fluid, associated with internal leakage of the hydraulic components, make these systems low energy efficient. In order to improve their energy efficiency, digital hydraulics emerges as a promising solution mainly for mobile applications. In this paper a hydraulic positioning system for aircraft control surfaces using a multi-chamber actuator controlled by on/off valves and a digital pump is proposed. The use of a digital pump with three fixed displacement pumps can provide eight different volumetric displacement outputs. The multi-chamber actuator with four areas can operate in two different modes, normal or regenerative, resulting in six different equivalent areas. The regenerative mode allows the actuator to achieve higher actuation velocity values with smaller pumps. These equivalent areas combined with the different supplied flow rates can deliver 43 different discrete output velocity values for the actuator, in steady-state. For the system dynamic analyses, three mathematical simulation models were developed using MATLAB/Simulink and Hopsan, one for the digital system, and two for the conventional solutions applied in aircraft (Servo Hydraulic Actuators (SHA) and Electro Hydrostatic Actuator (EHA)). The simulation results demonstrate that the digital actuator can achieve, for position control, a maximum position error, in a steady-state, of 0.7 mm. From the energy consumption point of view, the digital circuit consumes 31 times less energy when compared with the SHA and 1.7 when compared to the EHA, resulting in an energy efficiency of 54%.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48359088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-29DOI: 10.13052/ijfp1439-9776.23311
E. Frosina, G. Marinaro, A. Amoresano, A. Senatore
Spool valves are subject to a deteriorated performance and noise due to the occurrence of cavitation phenomena. It is well known that cavitation effects the performance of the component and causes an unwanted noise. The noise sound levels are influenced by many parameters like geometries and opening areas. In this paper a simple valve body made in plexiglass has been tested analyzing the cavitating area in U-grooves. A dedicated test rig has been equipped with a high-speed camera to acquire images of the phenomenon. A numerical three-dimensional CFD model has been built up using the commercial code. Experimental imagines have been compared with the numerical results showing a high accuracy on the prediction of the gaseous cavitation. The numerical results allow separate examination of several distinctive flow characteristics, which show favorable consistency with experimental observation and a periodic evolution of cavitation structure.
{"title":"Numerical Simulation of a Spool Valve in Gaseous Cavitation Conditions","authors":"E. Frosina, G. Marinaro, A. Amoresano, A. Senatore","doi":"10.13052/ijfp1439-9776.23311","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.23311","url":null,"abstract":"Spool valves are subject to a deteriorated performance and noise due to the occurrence of cavitation phenomena. It is well known that cavitation effects the performance of the component and causes an unwanted noise. The noise sound levels are influenced by many parameters like geometries and opening areas. In this paper a simple valve body made in plexiglass has been tested analyzing the cavitating area in U-grooves. A dedicated test rig has been equipped with a high-speed camera to acquire images of the phenomenon. A numerical three-dimensional CFD model has been built up using the commercial code. Experimental imagines have been compared with the numerical results showing a high accuracy on the prediction of the gaseous cavitation. The numerical results allow separate examination of several distinctive flow characteristics, which show favorable consistency with experimental observation and a periodic evolution of cavitation structure.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47560195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-29DOI: 10.13052/ijfp1439-9776.23310
Philipp Albrecht-Zagar, R. Scheidl
In many exoskeleton applications where heavy lifting is involved (e.g. in military or industrial applications) hydraulic actuators are used because of their high power density. For such applications it is necessary to develop compact and light hydraulic components so that the exoskeleton’s mass and size are low and, therefore, wearing comfort is high and power consumption is reduced to a minimum. Crucial components of hydraulic exoskeletons concerning this weight aspect are hydraulic valves and particularly their actuators, since conventional solenoids contribute the lion share of valve size and weight. As one option to solve this weight and size problem the application of smart materials such as piezo-ceramics to electrically actuate hydraulic valves are seen. The contribution at hand deals with the systematic design of a piezo-actuator which shall be used to switch a hydraulic valve. To overcome the problem of very low strain of the piezo a mechanism for amplification via a bistable buckling beam is analyzed analytically and numerically and an actuator prototype is designed and manufactured. This paper intends to carve out crucial challenges such as the requirements for snapping through of the buckling beam, the bearings of the beam and the integration of the piezo stack.
{"title":"A Piezo-Electric Valve Actuator for Hydraulic Exoskeleton Drives","authors":"Philipp Albrecht-Zagar, R. Scheidl","doi":"10.13052/ijfp1439-9776.23310","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.23310","url":null,"abstract":"In many exoskeleton applications where heavy lifting is involved (e.g. in military or industrial applications) hydraulic actuators are used because of their high power density. For such applications it is necessary to develop compact and light hydraulic components so that the exoskeleton’s mass and size are low and, therefore, wearing comfort is high and power consumption is reduced to a minimum. Crucial components of hydraulic exoskeletons concerning this weight aspect are hydraulic valves and particularly their actuators, since conventional solenoids contribute the lion share of valve size and weight. As one option to solve this weight and size problem the application of smart materials such as piezo-ceramics to electrically actuate hydraulic valves are seen. The contribution at hand deals with the systematic design of a piezo-actuator which shall be used to switch a hydraulic valve. To overcome the problem of very low strain of the piezo a mechanism for amplification via a bistable buckling beam is analyzed analytically and numerically and an actuator prototype is designed and manufactured. This paper intends to carve out crucial challenges such as the requirements for snapping through of the buckling beam, the bearings of the beam and the integration of the piezo stack.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49329325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The hydraulic binary counter concept was proposed as a means to realize compact and lightweight digital hydraulic cylinder drives for exoskeleton actuation. This counter principle is based on hydraulically actuated switching valves which have a hysteretic response with respect to the pilot pressure. Manufacturing tolerances of the tiny components caused unexpected high leakage which, in turn, led to a malfunction of the system. In this paper a new sealing concept, is introduced to solve this problem. It is based on a non-contact seal (sealing gap), which exploits a self-regulating, elasto-hydrodynamic effect to reduce a rather large initial gap h0 – to allow a rough tolerance – into a very small sealing gap h(x) to avoid dry friction of valve spool movement on the one hand but have very small leakage on the other hand. As sealing, an annular flexible ring made, e.g. of PTFE, is used which combines sufficient flexibility to allow this self adapting mechanism to a sufficient extent and to stay the high pressure loads. For the mathematical analysis of the concept, an approximate elasto-hydrodynamic analytical model is used. It sets the gap pressure, obtained from the Reynold’s equation for the sealing gap, the elastic restoring forces of the sealing ring, and the imparting pressure in equilibrium. The sealing concept is then simulated with a numerical model built with the finite element code ABAQUS, this results are compared with the one of the analytical model. It solves the Reynolds equation by a user defined subroutine. The simulation results indicate that this sealing principle delivers way better results than standard gap seals despite its rough manufacturing tolerances with one order of magnitude higher tolerance ranges. The application of this concept is not limited to small valves as needed for exoskeleton hydraulics but can be transferred to conventional type of hydraulics as well.
{"title":"A New Elastic Non Contacting Sealing Concept for Valves","authors":"Scherrer Matthias, Scheidl Rudolf, Luckachev Evgeny","doi":"10.13052/ijfp1439-9776.2339","DOIUrl":"https://doi.org/10.13052/ijfp1439-9776.2339","url":null,"abstract":"The hydraulic binary counter concept was proposed as a means to realize compact and lightweight digital hydraulic cylinder drives for exoskeleton actuation. This counter principle is based on hydraulically actuated switching valves which have a hysteretic response with respect to the pilot pressure. Manufacturing tolerances of the tiny components caused unexpected high leakage which, in turn, led to a malfunction of the system. \u0000In this paper a new sealing concept, is introduced to solve this problem. It is based on a non-contact seal (sealing gap), which exploits a self-regulating, elasto-hydrodynamic effect to reduce a rather large initial gap h0 – to allow a rough tolerance – into a very small sealing gap h(x) to avoid dry friction of valve spool movement on the one hand but have very small leakage on the other hand. \u0000As sealing, an annular flexible ring made, e.g. of PTFE, is used which combines sufficient flexibility to allow this self adapting mechanism to a sufficient extent and to stay the high pressure loads. \u0000For the mathematical analysis of the concept, an approximate elasto-hydrodynamic analytical model is used. It sets the gap pressure, obtained from the Reynold’s equation for the sealing gap, the elastic restoring forces of the sealing ring, and the imparting pressure in equilibrium. \u0000The sealing concept is then simulated with a numerical model built with the finite element code ABAQUS, this results are compared with the one of the analytical model. \u0000It solves the Reynolds equation by a user defined subroutine. The simulation results indicate that this sealing principle delivers way better results than standard gap seals despite its rough manufacturing tolerances with one order of magnitude higher tolerance ranges. The application of this concept is not limited to small valves as needed for exoskeleton hydraulics but can be transferred to conventional type of hydraulics as well.","PeriodicalId":13977,"journal":{"name":"International Journal of Fluid Power","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42129634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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