Hydraulic Amplification Research Articles

Design and analysis of a piezo-actuated hydraulic micro-displacement amplifier with high bandwidth and large amplification ratio

Micro-displacement amplifiers show great potential for enhancing the performance of piezoelectric ceramic stacks. However, designing a compact micro-displacement amplifier with a high amplification ratio and broad bandwidth remains challenging. This article introduces a hydraulic micro-displacement amplifier driven by a piezoelectric ceramic stack with a large amplification ratio, high bandwidth, and eliminating parasitic displacement. Theoretical and simulation analyses are performed for the hydraulic micro-displacement amplifier, optimizing parameters such as edge thin ring thickness and spring stiffness. A prototype was fabricated and tested in a series of experiments. The experimental results demonstrate that, under steady-state conditions, the hydraulic micro-displacement amplifier achieves an amplification ratio of 26.12 with a standard deviation of 2.28. The maximum output displacement is 172.4 μm at 150 V, and the resonant frequency is 445 Hz under a 20 N load. This study provides a novel approach to designing micro-displacement amplifiers.

AI-driven optimization of dynamic vibration absorbers with hydraulic amplifier and mechanical inerter integration

Dynamic vibration absorbers (DVAs) have been widely employed in vibration suppression applications for decades. While DVAs offer an effective solution, they are limited by the need for a high mass ratio between the DVA and the primary system to achieve significant vibration attenuation. To overcome this, researchers have introduced lever mechanisms, allowing for enhanced vibration suppression without increasing the mass ratio. However, levers, commonly used as amplification mechanisms, suffer from high inertia and limited amplification, particularly in larger applications. Another limitation is when DVAs are employed for energy harvesting as a secondary objective, they exhibit high sensitivity to system parameter variations, requiring extensive optimization. Various optimization techniques have been applied to DVAs for multi-objective optimization, including fixed-point theory, which is complex and requires intensive mathematical derivation, and simple metaheuristic techniques such as genetic algorithms (GA). This study proposes four novel DVAs using a hydraulic amplifier (HA) to address the limitations of traditional lever mechanisms and a mechanical inerter to improve the vibration damping. Also, multi-objective optimization was performed using particle swarm optimization (PSO) which is considered innovative in this application and compared with commonly used genetic algorithms (GA). The governing equations were derived using Newton’s second law and solved numerically with the Runge-Kutta method. An AI-based approach was utilized for HA design. The results show that integrating HA and mechanical inerters significantly enhances vibration attenuation and broadens the frequency response. Additionally, the location of the mechanical inerter is critical in reducing vibration amplitude. Also, the multi-objective PSO outperforms GA in solution diversity and quality. The proposed integration of HA in DVAs offers potential applications across various engineering fields.

Analysis of the Newest Design of Axial Piston Hydraulic Machines with Reduced Friction Losses and Leaks

Problem. Analysis of modern achievements in the field of volumetric hydraulic drives to improve the technical level of construction and road machines. Goal. Study of the design of the latest foreign development related to the improvement of the technical level of axial-piston volumetric hydraulic machines, in particular pumps and hydraulic motors according to the scheme of Innas floating cylinders. This design, according to the proposal of its inventors, is intended to work as pumps with a flow of up to 7400 l/min or hydraulic motors with a working volume of up to 5000 cm3 at a pressure of up to 50 MPa. Methodology. Analysis of the results of comparative bench tests of the Innas axial piston pump of the latest development and volumetric hydraulic machines of various designs, in particular axial and radial piston, as well as gear ones. Results. According to the results of comparative tests, the new design of the Innas axial-piston pump is significantly ahead of other serial hydraulic machines in terms of efficiency. The total efficiency value of 96 % achieved in the Innas pump shows the promise of such hydraulic machines. Originality. Analysis of the results of experimental studies with the determination of the features of the structures of hydraulic machines in terms of volumetric and hydromechanical power losses. It is concluded that Innas hydraulic motors can be used in trailing volumetric hydraulic drives with hydraulic power amplifiers, for which the characteristic of friction in the displacement mode is the main one from the point of view of the accuracy of the execution of the specified control signals. Practical value. The given materials are useful for specialists in the field of mechanical engineering, in particular, the design of volumetric hydraulic drives for construction and road machines

A Novel Piezoelectric Energy Harvester for Earcanal Dynamic Motion Exploitation Using a Bistable Resonator Cycled by Coupled Hydraulic Valves Made of Collapsed Flexible Tubes.

Scavenging energy from the earcanal's dynamic motion during jaw movements may be a practical way to enhance the battery autonomy of hearing aids. The main challenge is optimizing the amount of energy extracted while working with soft human tissues and the earcanal's restricted volume. This paper proposes a new energy harvester concept: a liquid-filled earplug which transfers energy outside the earcanal to a generator. The latter is composed of a hydraulic amplifier, two hydraulic cylinders that actuate a bistable resonator to raise the source frequency while driving an amplified piezoelectric transducer to generate electricity. The cycling of the resonator is achieved using two innovative flexible hydraulic valves based on the buckling of flexible tubes. A multiphysics-coupled model is established to determine the system operation requirements and to evaluate its theoretical performances. This model exhibits a theoretical energy conversion efficiency of 85%. The electromechanical performance of the resonator coupled to the piezoelectric transducer and the hydraulic behavior of the valves are experimentally investigated. The global model was updated using the experimental data to improve its predictability toward further optimization of the design. Moreover, the energy losses are identified to enhance the entire proposed design and improve the experimental energy conversion efficiency to 26%.

Influence of wheel rotation resistance on oscillatory phenomena in steering drive of electric bus with electromechanical amplifier

Steering systems with an electromechanical amplifier (EMA) are a modern design solution compared to hydraulic and electro-hydraulic steering systems. Hydraulic steering amplifiers are used in the steering drives of modern trolleybuses and electric buses. If an electric motor powered from the power grid is used to drive the hydraulic pump in trolleybuses, then in electric buses, the source of electrical power is rechargeable batteries. Energy consumption to ensure the operation of the hydraulic power steering reduces the mileage of the electric bus between charging the batteries. Therefore, conducting research and substantiating the possibility of using EMA in electric buses is relevant and has important practical significance. Considering the design features of the electromechanical steering amplifier and the design of the steering axle of the Electron 19101 electric bus, a dynamic model of the drive for turning the controlled wheels of the electric bus was built on the spot. Based on the dynamic model of the drive for turning the controlled wheels of an electric bus with an electromechanical steering amplifier, a mathematical model of the drive and a stimulation model were developed in the MathLab Simulink environment for the study of oscillatory processes in the drive links when the wheels turn on a horizontal plane. The nature of the change of elastic torques in the links of the steering control drive of an electric bus with an electromechanical steering amplifier, the frequency of rotation of the rotor of the electric motor, the current strength in the windings of the rotor and stator of the electric motor, the angle of rotation of the steered wheels as a function of time was studied. It was found that the change in the moment of resistance to the rotation of the steered wheels increases smoothly, and the load on the drive links of the electromechanical power steering depends on the total gear ratio of the drive and its distribution between the gearbox and the steering rack. A decrease in the total transmission ratio of the drive leads to an increase in the speed of rotation of the driven wheels and an increase in elastic moments in the drive links. Transient processes in the electric part of the drive correspond to the characteristics of such electric motors in terms of the nature of the change and do not exceed the permissible values in terms of magnitude. It was established that the power characteristics of the electromechanical steering amplifier with the selected parameters and the electric motor can ensure the control of the wheels of the electric bus following the established requirements.

HAPSEA: Hydraulically Amplified Soft Electromagnetic Actuator for Haptics

Novel actuators that can provide squeeze, vibration, and localized forces while remaining soft and comfortable are essential for next-generation augmented reality applications. Despite this need, there are currently few soft actuator topologies that can provide high forces and high bandwidths at low voltages and temperatures. In this work, we present a new type of soft electromagnetic actuator architecture for haptics. These low-cost, easy-to-manufacture, and conformal actuators are composed of a coil, magnet, thin-film material, and water. Adding a thin ferromagnetic sheet further enables the creation of a latching actuator variant, which can improve force output while reducing power consumption. Each actuator combines low voltage (up to 2 V), high-bandwidth electromagnetics with hydraulics to amplify force output. In addition to force amplification, the hydraulics provide cooling and thermal mass, which enable the actuator to be used safely in wearables for longer durations. In this work, we characterize the output forces, frequency response, efficiency, and thermal profiles of the prototype actuators. Results from tabletop experiments show that with hydraulic amplification, a nonlatching actuator is able to exert 1.3 N of force at 4 A, and a latching actuator is able to exert up to 5.2 N when preloaded with 3.7 N of compression. Furthermore, the prototype actuator has a bandwidth of 30 Hz when operating in air. After 120 s of continuous operation (1.3 W) in ambient air (26 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C), the maximum actuator temperature reaches 36 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C, making it safe for haptic applications. Using these designs, we develop a prototype wearable wristband device that can render body-grounded squeeze and vibration. By expanding on the operating principles described in this work, novel augmented reality applications can potentially become possible.

A piezoelectric valveless pump with flexible actuators

A piezoelectric valveless pump with flexible actuators (PVPFA) is proposed, which owns advantages of flexible driving, changeable flow direction and high output performance. The PVPFA is consist of three flexible actuators and a pump body. The direction of pumping fluid can be changed by setting different fluid medium volumes in the hydraulic amplification chamber. Each flexible actuator adopts hydraulic amplification structure, which makes PVPFA provide higher output performance. The theoretical model of the factors affecting the flow rate of PVPFA is established and verified by experiments. The experimental results show that PVPFA obtains a maximum flow rate of 98.48 ml/min and a maximum pressure of 10.7 kPa. PVPFA provides a new idea for piezoelectric valveless pump.

Principle and Control of Active Engine Mount Based on Magnetostrictive Actuator

Engine mount system affects the automobile NVH performance. Active mounts would achieve excellent vibration isolation and relative displacement control performance in a broad frequency bandwidth by outputting controlled force to the mounting system. The actuator and control method of the active mounts determine the system performance. In this paper, an active mount based on the smart material, i.e., Terfenol-D rod, is proposed, which mainly includes three parts: rubber spring, magnetostrictive actuator (MA), and hydraulic amplification mechanism (HAM). Dynamic model of the active mount is correspondingly established. A state feedback control method based on x-LMS (Least-Mean-Square) algorithm is proposed as well. Specifically, with the consideration of the unmeasurable state parameters in the active mounting system, an x-LMS state feedback controller with the system state as the reference signal is constructed by employing Sage-Husa Kalman filter to realize the state estimation of the active mounting system. Then a detailed analysis of the proposed control method is conducted, with deriving iterative formula of tap-weight vector. Sequentially, the problem of the dependence on the excitation signal in the x-LMS algorithm is addressed. The feasibility and capability of the proposed control method are verified and evaluated by simulation of a two-degree-of-freedom active mounting system.

Temperature drift mechanism of deflector jet servo valve under temperature shock

To study the mechanism of the deflector jet servo valve under temperature shock, a complete temperature theoretical model is proposed in this article. The temperature change affects the performance change of the torque motor by affecting the drift of the air gaps’ thickness, the permanent magnets’ reluctance, and the magnetomotive polarization force. Moreover, the temperature variation will act on the flow coefficient of the pilot stage, the size of the deflector, and jet pan, which influences the performance of the pilot stage hydraulic amplifier. Furthermore, the armature components, including the stiffness of the spring tube, the stiffness of the feedback rod, and the armature’s arm of force, are also related to the temperature variation. Comprehensively, considering the interaction influence of these factors, by analyzing the electromagnetic characteristics of the torque motor, the fluid mechanics’ characteristics of the pilot stage hydraulic amplifier, and the temperature performance of the armature assembly, the temperature drift model of deflector jet servo valve is constructed, which is represented as a ninth-order nonlinear equation. Based on the equation, the influence of temperature on the control precision of the servo valve is analyzed. The calculation results show that in the range of 20°C–250°C, the impact of temperature on the control accuracy will exceed 30%, the flow coefficient is the most significant affecting on the control accuracy, followed by the structural deformation of the pilot stage is the second factor affecting the temperature drift, and other factors have little effect. Comparison with the experimental results, the temperature drift model of the deflector jet servo valve can predict the control accuracy caused by temperature and provide a theoretical foundation for the optimization of the deflector jet servo valve.

HYDRAULIC PRESSURE AMPLIFIERS INTEGRATED WITHIN THE HYDRAULIC LINEAR ACTUATORS

The rated pressure of common hydraulic pumps varies depending on their principle and geometric displacement but generally doesn’t significantly exceed 400bar threshold. While this is perfectly adequate for most industrial and off-highway applications, there are applications requiring very high force that cannot be achieved by the linear actuator supplied with common pump pressure due to the space constraints placed upon the actuator. Increasing the pressure by means of pressure amplification resolves this problem. This presentation deals with principle, design considerations, applications, and benefits of hydraulic cartridge pressure amplifiers integrated directly into the hydraulic linear actuators and developed by PistonPower. The resulting linear actuator with integrated pressure amplifier thus features higher power density compared to the conventional hydraulic linear actuators.

Non-dimensional analysis of an unsteady flow in a magnetorheological damper

Theoretical modeling is often applied to study magnetorheological dampers (MRDs) with dimensional and non-dimensional analyses. In contrast to dimensional models, non-dimensional analyses can eliminate the influence of dimensionality and reduce the number of redundant parameters to simplify theoretical modeling and provide more universal applicability. However, most previous non-dimensional analyses have been based on quasi-steady flows that cannot reflect the transient response of an MRD because of the key assumption that the fluid velocity changes instantaneously. This study presents an investigation of the transient response of an MRD using a non-dimensional analysis approach based on an unsteady model. We focus on the step response of the MRD with a step excitation of the piston speed, while the magnetic field is kept constant. For a comprehensive analysis, a set of dimensionless parameters are defined, including a non-dimensional coordinate, a non-dimensional time parameter, the Bingham number, a non-dimensional pre-yield thickness, a damping coefficient, and a hydraulic amplification ratio. The relationships between these dimensionless numbers are analyzed. An unusual “concave area” is found in the velocity profile instead of a simple rigid flow during the transient process under a magnetic field. However, when the non-dimensional time is 0.4, the delayed concave area disappears, and the rigid area fluid velocity reaches 98% of its stable value.

Piezoelectric drive hydraulic amplification flexible Braille contact device design and experiment

The purpose of this paper is to use the principle of hydraulic amplification and design a piezoelectric drive-based hydraulically amplified flexible Braille contact device with good performance output. In this paper, the structure and working principle of the Braille contact device are described, and the theoretical analysis and parametric design of the hydraulic amplification unit are carried out. The influence relationship between the displacement amplification and diameter and height of the reservoir are obtained by using MATLAB simulation analysis, whereas the output displacement of the piezoelectric vibrator and the flexible film under different driving voltages is measured by using a laser micrometer. Subsequently, the experiments are consistent with the theoretical analysis, and the correctness of the theoretical analysis is verified. Finally, experimental tests of the system are implemented. The results suggest that the displacement amplification ratio is 4.16, and the contact displacement formed by the flexible film is 0.226 mm. Thus, the requirements of the touch sensitivity standard for the blind are satisfied when the reservoir diameter is 20 mm and the reservoir height is 3 mm. The filling water is 7.5 ml, and the resonance frequency is 317.5 Hz. This study proves that constructing a Braille bump device in this way is feasible as well as effective.

Research on a hydraulic displacement amplifier for a piezoactuator

A piezoactuator-based hydraulic displacement amplifier with two flexible diaphragm spools and one rigid chamber is designed. The elastic characteristics and effective area of the diaphragm spool are theoretically and numerically analyzed. The influencing factors on the effective area of the diaphragm spool are studied by the finite element analysis method. On this basis, a proto-type is produced, and its measurement and control system is built. Experimental results show that the hydraulic amplifier prototype can achieve a stroke range of 540 μm and its amplification ratio is approximately 6.

Design and test of a piezoelectric micropump based on hydraulic amplification

To solve the problem of the small deformation of piezoelectric vibrators and improve the overall performance of piezoelectric micro-pumps, a flexible-diaphragm piezoelectric micropump is designed based on hydraulic amplification. The micropump uses a piezoelectric vibrator to provide its driving force, and fluid is delivered by driving the liquid to amplify the displacement of the piezoelectric vibrator. First, the working principle of the piezoelectric micropump is analyzed, and then theoretical analysis and displacement output tests of the hydraulic amplifier unit are carried out. The test results are consistent with those of the theoretical analysis, and the amplification factor of the hydraulic amplifier unit is 3.29. Finally, prototypes are produced and an experimental platform is built for testing. The results indicate that the best-performing piezoelectric micropump has a self-priming height of 1200 mm, an output pressure of 22.16 kPa, and an output flow of 23.18 ml/min. Compared with an ordinary piezoelectric pump, the overall performance of the piezoelectric micropump is greatly improved.

Simulation on an electro-hydrostatic actuator controlled by a high-pressure piezoelectric pump with a displacement amplifier

PurposeThe purpose of this paper is to provide a new hydrostatic actuator controlled by a piezoelectric piston pump and to reveal its characteristics.Design/methodology/approachIn this paper, a piezoelectric pump with passive poppet valves and hydraulic displacement amplifier is designed as a new control component in a hydrostatic actuator for high actuation capacity. A component-level mathematical model is established to describe the system characteristics. Simulation verification for cases under typical conditions is implemented to evaluate the delivery behavior of the pump and the carrying ability of the actuator.FindingsBy using the displacement amplifier and the passive distributing valves, simulation demonstrates that the pump can deliver flow rate up to 3 L/min, and the actuator controlled by this pump can push an object weighing approximately 50 kg. In addition, it is particularly important to decide a proper amplification ratio of the amplifier in the pump for better actuation performance.Originality/valueThe piezoelectric pump presented in this paper has its potential to light hydrostatic actuator. The model constructed in this paper is valid for characteristic analysis and performance evaluation of this pump and actuators.

Method of calculating the design parameters of a modulator anti-lock braking system with a high flow of working fluid

The design dimensions of the executive hydraulic cylinders of the brake system of heavy-duty mining dump trucks cause high fluid flow during the braking process. Therefore, dimensions of the anti-blocking system modulator spool pair require unique electromagnets or hydraulic amplifiers to control. These solutions do not allow the required modulator performance. Thus, a modulator scheme with a division of the flow of fluid from the source to the brake cylinders was developed. This scheme allows during emergency braking passing, an additional amount of fluid to cylinders through the valve, installed parallel to the main valve upon pressure increase phase and controlled by the pressure difference. The task is to develop a method for calculating the main structural dimensions of a modulator. The calculation of the valve of the second cascade, installed in parallel to the main stage, is carried out for the emergency braking mode with the maximum flow rate to ensure the required performance of the braking system. The balance of fluid flows equations is compiled at the key points. The flow rate of the fluid through each of the valves is determined by the Torricelli formula, and the pressure difference across the valves is assuned equal. The obtained relations allows building a family of Q-p curves, which can be used to select the diameter and stroke of the additional valve depending on the flow rate in the brake system.

Оптимизация расхода утечки электрогидравлического усилителя типа сопло-заслонка

Оптимизация расхода утечки электрогидравлического усилителя типа сопло-заслонка

Pressure Sensor Embedded Inductive Coil Toward a Wireless Pressure Sensing Stent

This paper reports the development of a wireless pressure sensing coil system by embedding a capacitive micro sensor onto a wire. The coil system, consisting of an inductor (coil itself) and multiple capacitors (sensors), formed a passive LC telemetry configuration for wireless sensing. The capacitive sensor, utilizing the movements of a liquid in a sealed chamber for hydraulic amplification, enabled high capacitance changes and amplified signal outputs. The capacitive sensor also produced digitized signal outputs as the liquid movement crossed a finite number of the interdigitated electrodes. Such characteristics were modeled and confirmed by establishing an equivalent fluidic circuit. The capacitive sensor was fabricated by grafting and polishing a copper wire piece on a silicon wafer, then performing standard microfabrication on the polished wire surface and filling a liquid into a sensor chamber. The fabricated pressure sensing coil system demonstrated a pressure sensitivity of 11.8 kHz/mmHg under a clinical pressure range of 0~206.9 mmHg in an ex vivo test with a water flowing tube, meeting the requirements for wireless detection of vessel restenosis. The sensitivity corresponded to the capacitance changes of 0.052 fF/mmHg and liquid displacement of 0.39 μm/mmHg. The fabricated coil system held a dimension of 2.5 mm in diameter and 7.2 mm in length in the form of a wound wire (copper, 260 μm in diameter). The embedded capacitive sensor consisted of a hydraulic chamber of 400×100×1 2 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and a microchannel of 500×20×1 2 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . [2020-0364]

Адаптивный алгоритм расчёта динамики гидромеханического следящего привода с дроссельным управлением

The technical, economic, and performance indicators of hydromechanical servo actuators with throttle control (HMSA/T) can be radically improved by structurally correcting the actuator initial configuration followed by parametrically optimizing the found solution. The conventional solution boils down to an analysis of partial correction problems. However, this adds difficulty to comparison of the results and entails a significant scope of refinement and adjustment works. The article presents a unified algorithm for settling matters concerned with structural and parametric correction of an HMSA/T as applied to the most efficient ways of changing the actuator initial structure: damping the hydraulic amplifier sliding valve and introducing additional feedbacks for the output section motion speed and derivative of pressure difference in the hydraulic amplifier outlet hydraulic lines. An integrated HMSA/T model is constructed on the basis of standard structural correction schemes and partial mathematical models of actuators, and the scheme of an algorithm for combined structural and parametric correction of the actuator is presented. It is shown that the algorithm can be implemented using limited computation resources with a quickly running application software.

STANDARDS IN FORCE MEASUREMENTS

Force measurement is an important aspect in testing and determining the characteristics of units, machine parts and materials, building materials and structures, the quality of metallurgical products, as well as when assessing the conformity of force and weight transducers. The purpose of this study is to select the optimal procedure and methodology for realization, storage and transferring of the unit size of force in the country, as well as to ensure its traceability to the international system of SI units. This paper analyzes existing methods of realization, storage and transferring of unit size, such as deadweight force standard machines, hydraulic amplification force standard machines, lever amplification force standard machines and systems (groups) of several force transducers (BU system) that can be used as reference by metrological institutes and calibration laboratories. The main principles of operation of the above mentioned machines of realization of a unit of force are considered, including the components of measurement uncertainty and the nature of their origin with the possibility of further consideration in the uncertainty budget. The calibration and measurement capabilities of the world's leading metrological institutions, which maintain different classes of force standard machines for reproducing the size of a unit of force, namely the measurement range, measurement uncertainty, as well as overall dimensions, operating features, etc. are analyzed. The results of the analysis of the disadvantages and advantages of the three main classes of force standard machines for reproducing the size of a unit of force are presented in this article. Conclusions are made on the creation of a national standard of the force unit based on the installation of lever amplification force standard machines, which are based on the analysis of methods of reproduction and transfer of the size of a unit of force, which will occupy positions among the world's leading metrological institutions.