Valve Actuation Research Articles

Emerging magnetic-responsive hydrogel actuators with anisotropic shape for intracardiovascular directional motion

A magnetically responsive valve actuator inspired by the starfish shape and fabricated with hydrophilic and hydrophobic surfaces was developed. The surface morphology and wettability of the magnetically responsive colloidal crystal hydrogel actuator were characterized using scanning electron microscopy and contact angle measurements. The actuator, resembling a flower, consists of Poly(HEMA-co-AAm)/Fe3O4/PDMS, exhibiting distinct Janus wettability with hydrophobic Fe3O4/PDMS and hydrophilic Poly(HEMA-co-AAm) surfaces. The directional movement of water droplets on the V-shaped structured film confirmed the anisotropic wetting behavior, influenced by the film’s wettability and structural dimensions. Moreover, the actuator demonstrated responsive angular and positional adjustments under varying magnetic fields, facilitated by embedded Fe3O4 particles aligning with magnetic lines of force. In experimental setups simulating intravascular applications, the actuator exhibited controlled movement within tubes and demonstrated effective adhesion to heart valve injuries under magnetic guidance. Additionally, a layered inverse opal film within the actuator showed promising capabilities for unidirectional fluid permeation, enhancing its functional versatility. These findings underscore the potential of the magnetically responsive colloidal crystal hydrogel actuator for biomedical applications, particularly in minimally invasive cardiac interventions requiring precise actuation and adhesive functionalities.

Active fault-tolerant control with prescribed performance and reachability judgement for the altitude ground test facility

This research proposes an active fault-tolerant control (AFTC) method based on reachability judgement with asymmetric appointed-time prescribed performance to ensure the safety of altitude ground test facility (AGTF) under potential valve actuator and sensor faults. Firstly, a long short-term memory (LSTM) neural network is employed for fault diagnosis. Given the unique characteristics of AGTF, the equivalent multiplicative fault is introduced to ensure the successful fitting of the fault diagnosis network. Then, a reachability judgement network based on the distance field on grids (DFOG) method is designed to assess the impact of faults on subsequent tasks of the system, thereby ensuring the safety of the AGTF. Subsequently, this study proposes an error transformation function of prescribed performance control (PPC) that ensures error convergence even in cases of asymmetric performance function. This enables the performance boundaries to be further reduced to improve the control performance of the system. Finally, experiments validate the effectiveness of the methods proposed in this manuscript.

Multi-body dynamics modeling and energy consumption optimization of electromagnetic mechanical fully variable valve system

Electromagnetic Mechanical Variable Valve Actuation (EMVVA) technology has the capability to improve engine performance and decrease pollutant emissions. A new type of EMVVA composed of electromagnetic driver and mechanical transmission is proposed to realize the flexible adjustment of valve parameters whether the valve is open or closed process. The geometric mathematical model of the mechanical transmission is developed based on the motion laws of the valve and the geometrical construction of the mechanical transmission, and the conjugate cam curve is solved. A multi-body dynamic model is constructed to calculate the driving torque and energy consumption needed by the mechanical transmission based on the mass, rotational inertia, centroid position of the parts, combining the normal contact force model and the friction model of the clearance contact pair at the same time. Based on the geometric model and multi-body dynamics model, the test platform is established. The test results demonstrated that within the specified valve lift, EMVVA system could accomplish variable valve lift, variable valve timing, and variable valve duration at maximum lift. The maximum timing error does not exceed 1° crank angle, and the maximum valve lift error does not exceed 0.25 mm at 11 mm valve lift. In addition, the error of driving torque between the multi-body dynamics model and the test is less than 0.3 [Formula: see text].Low energy optimization of mechanical transmission was completed using the NSGA-II method and multi-body model. According to the results of the optimization, energy consumption was reduced by 14%, and the peak driving torque was decreased by 54.3%.

Implementing Component Degradations into a Modelica Model of an iPWR System to Develop Health Monitoring Techniques

The economic operation of small modular reactors will partly rely on managing and reducing inspection and maintenance activities while supporting new operational paradigms like load-following. Turbine control valves throttle the steam from the steam generator into the steam turbine while maintaining the pressure within the steam generator at a constant set point. Degradation of these components could impact the ability to manage electrical power production. Utilizing the Idaho National Laboratory Hybrid repository and the Oak Ridge National Laboratory TRANSFORM library developed for multiphysics simulations in Dymola/Modelica, an integral pressurized water reactor system was modeled based on the available specifications of the NuScale power module. The effects of various component degradation modes have been implemented into the model in order to simulate faulted plant data during both steady-state and load-following operations. The fault modes resemble different physical fault modes that may occur at an operating nuclear power plant; a leaking turbine control valve and a valve actuator failure due to loss of hydraulic pressure have been implemented. A neural network autoencoder is employed in conjunction with statistical analysis, namely, simple signal thresholding (SST) or sequential probability ratio testing (SPRT), to identify the presence of a fault. Fuzzy logic is additionally employed in a novel and promising manner to classify the state of the system based on the cumulative sum of the neural network residuals. SST and SPRT are both successfully validated using healthy data and proved capable of identifying both fault types; fuzzy logic identified the false positives and classified the faulted data correctly.

Design, development, and testing of active valve piezo-hydraulic pump

Valves play a major role in rectifying the fluid flow through piezo-hydraulic pumps, which may be active or passive. Passive valves operate due to changes in the fluid pressure whereas active valves are operated through control signals. This paper presents a novel design of an active valve chamber assembly for a piezo-hydraulic pump. It is a novel design since none of the research publications has addressed the application of a Flexurally amplified piezoelectric actuator (FAPA) for valve actuation in active valve chamber assembly. The piezo-hydraulic pump design is done using solid edge design software. FAPA’s are used for pumping and valve actuation. Structural analysis with experimental verification for the valve chamber component is presented. The valve opening and the pumping displacement are mathematically modeled in MATLAB Simulink software. Also, mathematical simulations for pump flow rates at different actuation frequencies and voltage are discussed. The piezo-hydraulic pump components are fabricated and assembled with the actuators. Experimental investigations on the flow rate performance of the active valve piezo-hydraulic pump are carried out with changing frequency and voltage amplitude of actuators. The interpretation of results is done by comparing the experimental and simulation results. During experiments, the pump delivered a maximum flow rate of 4.5 ml min−1 at 140 V when actuated at 0.25 Hz actuation frequency.

A comprehensive mathematical theory and optimized design of a high-frequency electro-pneumatic variable valve actuator for a camless IC engine

This paper discusses the development of a detailed mathematical theory and its use for the design of an electronically controlled, double-acting Variable Valve Actuation (VVA) mechanism for a camless internal combustion engine, that offers a comprehensive control over the timings and the motion of the valves such that any arbitrary time-variation of the valve lift profile can be obtained at variable rotational speeds of the engine shaft. The developed theory encompasses the thermo-fluid-dynamic as well as the applied-mechanical aspects of the actuator cylinder-engine valve system performance, the dynamics of the valve actuation being characterized by parameters such as valve opening duration, peak lift and seating velocity. The prediction of the mathematical theory compares well with several experimental data sets obtained from an in-house pneumatic VVA set-up. A new design methodology is formulated for determining the appropriate dimensions of the actuator, operating thermodynamic parameters and the electronic control of the various valve events for a desired range of engine rotational speed. Several parameters in the new design philosophy are kept within acceptable ranges established from time-tested data obtained from conventional cam-based valve actuation. For example, a new pneumatic cushioning strategy has been developed that is simple, effective and energy-efficient, and is able to keep the valve seating velocity within an acceptable range (0.08–1.13 m/s). The work also discusses the implementation of several constraints that are necessary for the design of a practically viable pneumatic actuator. The evolution of a design matrix map for the electro-pneumatic VVA is quantified for the engine rotational speed varying up to 5500 rpm.

A novel robust MPC scheme established on LMI formulation for surge instability of uncertain compressor system with actuator constraint and piping acoustic

This paper presents a new control method for surge instability of the compressor system. Due to the importance of the active control approach in improving the efficiency of the compressor system, a new scheme based on the model predictive control (MPC) technique has been considered to control surge which gives the benefits of control signal optimization by considering the constraints on states and input. Because of designing a novel MPC by using of linear matrix inequality scheme, the optimization problem is solved in less time and with less complexity. The proposed method is able to consider the limitation of the close coupled valve actuator and also covers the uncertainty on the model. In addition, the developed model describes the nonlinear behaviour of the compressor system and handles the effects of the pipe on surge instability. Using Lyapunov theory, the stability of the closed-loop system under the proposed robust active controller is shown. The simulation results show the high pressure and high efficiency operation of the system under study in different operating conditions.

Research on vibration test method of electric actuator

Abstract The stable, safe, and reliable operation of electric actuator valve systems is of great significance in industrial production. This paper proposes a vibration test method for electric actuators, employing the test to meet the test severity level as the first priority, with random frequency vibration within 10 Hz to 1000 Hz. The vibration acceleration is loaded with a Gaussian distribution, which can be used to simulate the irregular vibration of electric actuators in the actual working conditions of the working environment. The test is divided into up and down vibration (z-axis), left and right vibration (x-axis), and front and rear vibration (y-axis) in three directions independently to verify the electric actuator from the mechanical structure and the circuit structure in order to meet the reliability requirements of the actual production.

Multimethodology based on Design-to-Value (DtV), integrated with simulation techniques and prioritization of teamwork for the optimization of a pneumatic rack & pinion actuator

The investigations here presented focus on the redesign and innovation of a pneumatic rack and pinion actuator for valve actuation, as a case study for investigating the potential of a multimethodology based on the Design to Value (DtoV) process, coupled with design techniques utilizing FEA simulations and giving high priority to teamwork. The final objective of this case study is to show how it is possible to optimize the design, increasing weight efficiency while maintaining performance, and to simplify it, with a reduction of components construction complexity, according to the growing demand for a lean production. The principle that guided all the activities was valorizing the power of teamwork, focusing the team on Safety and Reliability. In an initial phase, all the instruments foreseen by “Design-to-Value” process have been applied, obtaining a classification of the contents of the product constituting its sources of value. Subsequent outputs are proposals for efficient construction solutions, driving a second phase, dedicated to the re-design of the actuator. The peculiarity of this project has been to combine the “Design by Formulas” techniques with advanced FEA simulations (“Design by Analysis”), aiming to stress, deformation, and topology optimization. A two-step experimental validation is used, based on a preliminary “mockup” prototype followed by a complete detailed prototype, for confirming the results of the calculations and simulations, by directly performing a series of in-depth tests. Preliminary obtained results show that the approach based on the described multimethodology, makes it possible to optimize the design of the actuator, maintaining safety, reliability, and performance. In the case studied, the weight reduction is expected to be 8% and economic efficiency increase is expected to be near 20%.

Performance evaluation of linear variable valve actuation for a linear engine generator

The Joule cycle Linear Engine Generator (LEG) is a promising power generation technology with the potential to achieve zero carbon emissions. However, the LEG expander valve actuation system presents unique challenges due to its lack of a traditional crankshaft, the need for swift valve lift and reversal, and variable lift. This paper presents a Linear Variable Valve Actuation (LVVA) system for a LEG prototype. The LVVA system is powered by voice coil motors. Rigorous experimental investigations were conducted to analyze crucial performance factors, including energy consumption, force balance, energy flow distribution, and the relationship between valve lift duration and energy consumption. The results show that the LVVA system can achieve the desired valve lift and timing, as well as very small variations in LEG performance compared to the model using an ideal lift curve. The LVVA accounts for approximately 3.59 % of the LEG power output. The energy consumption of 1.607 J per valve stroke provides a slight advantage over traditional actuation systems. The obtained optimal lift curves were used to refine the LEG model. The influence of valve lift curves on LEG performance was evaluated which reveals rapid valve openings and relatively short duration contributing to improved LEG performance.

Electro–Thermo–Mechanical Characterization of Shape Memory Alloy Wires for Actuator and Sensor Applications, Part 2: High‐Ambient‐Temperature Behavior

The typical phase transformation temperatures of commercially available shape memory alloys (SMA) for actuator applications are in the region of 80–90 °C for austenite finish and around 60 °C for martensite start. That limits the areas of application for SMA actuators, as increased ambient temperatures restrict their functionality. Especially in the industrial and automotive sectors, operational temperatures of 80 °C and higher are commonly required. This article discusses the limits of operation temperatures for commercially available SMA actuator wires. Also, methods to increase this critical temperature limit, at which the SMA actuation strain falls below a certain threshold, are proposed. By means of electrothermal actuation experiments, the influence of the variation of bias loads and an additional training method are investigated. Supported by these results, an exemplary valve actuator system is designed, which exhibits consistent stroke in a wide range of ambient temperatures. All experiments and measurements are conducted on a custom designed test bench with the same commercially available SMA wire. The test bench is in the following used again to evaluate the designed SMA valve actuator.

Study on the soft-landing of large inertia valve based on multi-objective optimization of annular gap

Variable valve mechanism and its technology are widely used in vehicle diesel engines. As a critical component, the performance of reciprocating actuator is the guarantee for the realization of electro-hydraulic variable valve. In order to solve the problem of high setting speed in electro-hydraulic camless variable valve system, a variable valve actuator based on annular gap buffer is proposed and optimized to realize quick closing and soft landing. The experimental results show that the actuator can achieve the purpose of setting buffer, and the setting speed is 0.5 m/s with 15 ms of closing time. AMESim is used to build the system simulation model and calibrated by experiments. The simulated lift curve is close to the experimental curve, and its Pearson coefficient is 0.9995. The influence of structural parameters on the system driving ability and buffering effect is studied through the model. According to the simulation results, the annular gap eccentricity will affect the buffering effect. When the eccentricity increases from 0.005 to 0.035 mm, the landing velocity increases by 0.1 m/s and the valve closing time decreases by 0.9 ms. NSGA-II method is used to optimize the structural parameters of the annular gap, and an obvious Pareto front is obtained and the optimal solution is applied in next experiments. The landing speed is reduced from 0.5 to 0.25 m/s, and the landing time is still less than 15 ms. This paper provides a simple cushioning scheme for electro-hydraulic camless variable valve soft landing which is independent of proportional valve.

Development of real-time density feedback control on MAST-U in L-mode

In this paper we report on the development and demonstration of density feedback control for MAST-U. Sinusoidal perturbations are used to measure the frequency response from a deuterium gas valve (actuator) to line-integrated core electron density measured by the interferometer (sensor). In the frequency range relevant for control design, only two system-identification experiments were needed to regress a first-order dynamic model. This control-oriented model informs the offline design of a proportional integral controller with the established loop-shaping controller design method. After offline verification of the controller implementation, control is demonstrated by experimentally tracking a staircase reference for the line-integrated electron density. This paper demonstrates the efficiency of controller design using system-identification and loop-shaping, providing reliable density control for MAST-U.

Dynamic performance prediction and experimental analysis of wet clutch actuator considering thermal flow characteristics

The hydraulic actuator system (HAS) for wet clutches in heavy-duty vehicle transmissions is required to have a fast response and high precision in the pressure regulation procedure. Conventional pressure control valves for HAS are almost slide spool structures, which perform a large flow force at a high flow rate. An open-center spool structure is designed and developed in this paper, which is a combination of a traditional slide spool and a valve sleeve. It has an orifice-groove combination throttling orifice, which can take into account the large through-flow capacity and small flow force. Firstly, to deeply understand the mechanism of pressure variation in the clutch chamber, a high-fidelity dynamic characteristic mathematical model of HAS considering the oil temperature is proposed. Secondly, the functional relationship between the oil temperature on the medium physical property parameters and the orifice thermal flow parameters in the model is deduced in detail. An experimental bench to measure the pressure valve dynamic performance and actuator pressure regulation characteristics in a wide temperature domain is then designed and implemented to validate the accuracy of the simulation model. Finally, the mechanisms of oil temperature and system pressure on pressure impact and pressure response are quantitatively analyzed in association with a supervised learning algorithm. The feasible domains of the two adjustable variables are also explored. This study provides a new perspective on dynamic control and energy saving of HAS pressure valves and a new method for the prediction of HAS performance under complicated operating conditions.

Deep reinforcement learning based active surge control for aeroengine compressors

This study proposes an active surge control method based on deep reinforcement learning to ensure the stability of compressors when adhering to the pressure rise command across the wide operating range of an aeroengine. Initially, the study establishes the compressor dynamic model with uncertainties, disturbances, and Close-Coupled Valve (CCV) actuator delay. Building upon this foundation, a Partially Observable Markov Decision Process (POMDP) is defined to facilitate active surge control. To address the issue of unobservability, a nonlinear state observer is designed using a finite-time high-order sliding mode. Furthermore, an Improved Soft Actor-Critic (ISAC) algorithm is developed, incorporating prioritized experience replay and adaptive temperature parameter techniques, to strike a balance between exploration and convergence during training. In addition, reasonable observation variables, error-segmented reward functions, and random initialization of model parameters are employed to enhance the robustness and generalization capability. Finally, to assess the effectiveness of the proposed method, numerical simulations are conducted, and it is compared with the fuzzy adaptive backstepping method and Second-Order Sliding Mode Control (SOSMC) method. The simulation results demonstrate that the deep reinforcement learning based controller outperforms other methods in both tracking accuracy and robustness. Consequently, the proposed active surge controller can effectively ensure stable operation of compressors in the high-pressure-ratio and high-efficiency region.

Quantitative Comparative Study on the Performance of a Valve-Controlled Actuator and Electro-Hydrostatic Actuator

The development of the electrification of aircraft has prompted aviation hydraulic systems to shift from traditional centralized valve actuators (CVAs) to electro-hydrostatic actuators (EHAs). In this paper, aiming at the demand for a quantitative comparison of performance between CVAs and EHAs, CVA and EHA prototypes with the same power level and test platform were developed. Then, based on the power flow and dynamic models of the CVA and EHA, simulation and experimental comparative tests were conducted using different load spectrum test conditions and step response test conditions. The comparative test results showed that the efficiency of the EHA was better than that of the CVA, and the dynamic response of the CVA was better than that of the EHA. Finally, a power loss quantification and parameter sensitivity analysis were performed to reveal the impact of different parameters on the different power losses and to provide suggestions for improving the performance of CVAs and EHAs.

Variable valve actuation for efficient exhaust thermal management in an off-road diesel engine

Exhaust thermal management (ETM) is crucial for effective emission mitigation in integrated exhaust aftertreatment systems of modern off-road diesel powertrains. However, conventional ETM strategies incur a significant fuel efficiency penalty. This study addresses the issue by investigating the application of variable valve actuation (VVA) for efficient ETM. For the first time, this investigation is conducted on a representative state-of-the-art off-road powertrain platform. It explores four VVA strategies with unprecedent level of rigour, employing a model-based approach that enables extended insights beyond stand-alone testing. Experiments with an EU Stage-V off-road diesel engine provide the baseline for validating a one-dimensional model in GT-Suite. A meticulously calibrated, predictive combustion model enables precise cross-evaluation of how VVA strategies affect exhaust gas temperature (EGT), efficiency, engine-out emissions and combustion characteristics, considering all trade-offs. VVA simulations are performed at three low-load operating points, where engine operation borders catalyst light-off temperature (LOT). The findings impartially confirm that cylinder deactivation (CDA) and intake modulation are the most promising VVA strategies for off-road engines, with EGT increments surpassing +250 °C and +150 °C respectively, accompanied by minor fuel penalties (up to +3.5 %). CDA demonstrated fuel savings of up to −2.5 % at certain points, due to reduced pumping and friction losses. Intake modulation displayed large reduction in engine-out NOx (>90 %) and minimal penalties in carbon emissions (HC, CO, and soot). The results underscore VVÁs potential as an efficient ETM option to help the next generation of off-road diesels to comply with upcoming EPA Tier 5 emission legislation.

Low-Cost Throttle-by-Wire-System Architecture for Two-Wheeler Vehicles

<div>This article investigates the performance of a low-cost throttle-by-wire-system (TbWS) for two-wheeler applications. Mopeds/scooters are still restricted as environmentally harmful. TbWSs can contribute to environmental protection by replacing conventional restrictors. Its consisting of an anisotropic magnetoresistance (AMR) throttle position sensor and a position-controlled stepper motor-driven throttle valve actuator. The decentralized throttle position sensor is operating contactless and acquires redundant data. Throttle valve actuation is realized through a position-controlled stepper motor, sensing its position feedback by Hall effect. Using a PI controller, the stepper motor position is precisely set. Both units transmit and receive data by a CAN bus. Furthermore, fail-safe functions, plausibility checks, calibration algorithms, and energy-saving modes have been implemented. Both modules have been evaluated through hardware-in-the-loop testing in terms of reliability and measuring/positioning performance before the system was integrated into a <i>Peugeot Kisbee 50 4T</i> (Euro 5/injected). Finally, the sensor unit comes with a measurement deviation of less than 0.16%, whereas the actuator unit can approach throttle valve positions with a deviation of less than 0.37%. The actuators’ settling time does not exceed 0.13 s in the case of stable, step loss free, and noiseless operation.</div>

Modelling and cycle‐by‐cycle control of an electromechanical engine valve actuator with impact speed limiter based on hydraulic damper

AbstractVariable valve actuation (VVA) systems based on electromechanical valve actuators (EMVAs) enable a flexible operation and management of internal combustion engines that results in a reduction of pollutant emission and fuel consumption while improving engine power and efficiency. However, to achieve the benefits promised by EMVAs, it is of utmost importance to guarantee the catch of the valve by the system magnets with an acceptable impact speed of the valve at the end‐strokes. Valve catching failures can severely damage engine valves while high impact speeds induce mechanical wear and unacceptable noise. The soft landing control of the valve at the end‐strokes is challenging because of system nonlinearities, parameter uncertainties, and external disturbances. The complexity of the control design increases further when industrial cost‐effective solutions are sought. This paper presents a novel solution for reducing the impact speed of the valve without the use of costly position valve sensors. The proposed solution leverages on a small hydraulic damper (HD) embedded into the EMVA and a feedback cycle‐by‐cycle controller. The passive element reduces the impact speed while the controller adjusts at every engine cycle the EMVA coil currents based on pressure peaks detected in the HD to guarantee valve catching while steering the impact speed toward its minimum. The design of the controller exploits a physics‐based model that maps the pressure peak in the HD onto the impact speed and a gradient descent algorithm is adopted searching the minimum. The closed‐loop permanence is assessed in simulation by using an experimentally validated EMVA model and considering detailed dynamics of the HD. Numerical results show the ability of the proposed control architecture to reduce the impact speed and its robustness to parameters variations (oil temperature) and external disturbances (gas pressure forces).

Iterative Learning for Laboratory Electro-Hydraulic Fully Flexible Valve Actuation System Transient Control

<div>Fully flexible valve actuation (FFVA) is a key enabling technology of internal engine combustion research and development. Two laboratory electro-hydraulic FFVA systems have been developed and implemented in R&D test cells. These FFVA systems were designed using repetitive control (RC), which is based on internal model principle (IMP), for constant engine speed operation. With the engine operating in a steady-state condition, the valve profile input is periodic. This can be accommodated by a repetitive controller, which provides the function of flexible control to step changes in valve lift, valve opening duration, and cam phase angle position.</div> <div>During engine speed transients, as the valve reference trajectory becomes aperiodic in the time domain, the controllers based on the linear time invariant (LTI) IMP, such as RC, are no longer applicable. Engine speed transient control is a desired function to engine research and other similar applications, such as motor control. Several investigations are reported with limited results because of the assumption of IMP and periodic input.</div> <div>This article presents the control design and verification of the iterative learning control (ILC) algorithm for the laboratory electro-hydraulic FFVA system. This algorithm tracks valve lift profiles under steady-state and transient operation. A dynamic model of the plant was obtained from experimental data to design and verify the effectiveness and robustness of this approach. The simple structure of the ILC in implementation and low cost in computation are crucial benefits to recommend the ILC. It is not an IMP-based approach, and its structure does not depend on the system input. Therefore, it has higher robustness to perturbation and modeling errors than other control methods for repetitive valve lift profile tracking tasks.</div>