High performance proportional valves are commonly utilized for precise control of aircraft actuators to ensure flight safety. Fault diagnosis play a crucial role in maintaining equipment reliability. ...However, traditional diagnostic methods using vibration signals face challenges such as inability to directly measure failure points, fault characteristics being influenced by sensor position, and large data processing volume, limiting engineering application scope. This paper introduces a valve spool wear fault diagnostic method based on energy loss model and data hybrid drive, leveraging throttling loss characteristics. An energy loss failure mechanism model, incorporating differential pressure and flow rate of valve port, was established, and experimentally verified. This method effectively addresses the limitations of vibration sensors in diagnosing aviation hydraulic systems. By combining particle swarm optimization algorithm with deep extreme learning machine, the number of neurons, weight distribution, and data set ratio are rapidly optimized, reducing data processing complexity and enhancing diagnostic efficiency. Comparative tests demonstrate a significant increase in average diagnostic accuracy rate, with more than 8% improvement after integrating energy loss information and particle swarm optimization, reaching over 98%. The proposed method exhibits superior performance in average diagnostic accuracy rate and stability compared to other methods and can be served as a valuable reference for predicting faults in aviation hydraulic valves.
For analyzing ejector's performance in the system, an ejector for a 10 kW polymer electrolyte membrane fuel cell (PEMFC) system was first designed, manufactured, and a 10 kW PEMFC system bench was ...built up. A proportional valve and PI pressure feedback control method were adopted to control the hydrogen supply and anode inlet pressure. During the test, performances between dead-ended anode (DEA) mode and ejector mode were compared. Ejector's performances in the system, i.e., volume flow recirculated ratio, difference pressure, dynamic responses of primary pressure, anode inlet pressure, and recirculated gas flow rate during the purge process and current variation condition, were investigated. The results show that pressure adjustment is accurate, continuous, and fast using the proportional valve and PI pressure feedback control method. The hydrogen consumption rate in the ejector mode can reduce from 5% to 10% compared with the rate in the DEA mode except for the stack current 5 A and 10 A conditions. For better water removal out of the anode channel in ejector mode, the maximum stack power increases from 5.11 kW (DEA mode) to 9.56 kW (ejector mode). Anode pressure surge caused by the purge valve switching enhances the ejector's recirculated performance significantly.
•An ejector for a 10 kW PEMFC system is designed, manufactured and evaluated.•The stack in ejector's mode shows a better performance than that in DEA mode.•Hydrogen recirculation can reduce the hydrogen consumption.•The proportional valve with the PI pressure feedback method can accurately control the anode inlet pressure.•Anode pressure surge can enhance ejector's recirculated performance.
•A modified magnetic cycle method fusing of local finite element and mathematical models was proposed.•Coupled dynamic mathematical models for an electro-hydraulic proportional valve based on ...mechanical, electrical, electromagnetic and fluid subsystems were presented.•A coupled finite element model for an electro-hydraulic proportional valve considering all subsystems was established.
On the basis of differences of the magnetoresistance, magnetic field direction and relative permeability in metal components, a magnetic cycle method with modifications also characterizing magnetic flux densities of different components in real time is firstly proposed, thus establishing mathematical models for the electromagnetic subsystem of an electro-hydraulic proportional valve. Further integrating electrical, electromagnetic, fluid dynamic and mechanical models together, analytical and fully coupled mathematical models are achieved so that nonlinear dynamic performance determined by the structural parameters, materials, fluid, driving strategies and interaction of subsystems will be captured effectively. Secondly, a coupled finite element (FE) model with all subsystems is also established, and dynamic behaviors under different driving strategies such as the high-low voltage (HL), direct current (DC) and pulse width modulation (PWM) are reflected through the moving mesh method in COMSOL Multiphysics, further suggesting the HL strategy as the better one because of small overshoot and shortest response times. Under the same driving strategy such as PWM, results of two models are highly similar to each other with the maximum time difference of 5 ms and the absolute error of steady-state position of 0.0104 mm. Therefore, two dynamic models are relatively accurate, and such an integrated method presents another reference for predicting dynamic behaviors of complex valves.
The main objective of this article was to analyse flow forces acting on a spool of a proportional control valve in the initial phase of the spool gap opening. Accordingly, modification of the spool ...geometry has been proposed in order to reduce flow force values. The modification consisted in making small circular undercuts at the apex of main triangular grooves, which were made on the spool. The undercuts were made in order to improve flow characteristics, for the gap width less or equal to 0.40mm. Two arrangements of undercuts were tested. In the first version the undercut was made only on one groove, while in the second version two undercuts were located symmetrically on both sides of the spool. Simulations were carried out by the means of CFD methods and allowed both axial and radial flow forces to be determined. The simulation results showed that the use of a single undercut allowed the valve to operate at a very low flow. However, a significant radial force asymmetry appeared. The use of symmetric undercuts reduced the unevenness of radial forces, with a relatively small increase in flow rate and axial force. The obtained axial force values were next verified experimentally on a test bench.
•CFD analysis of a proportional control valve.•Obtaining flow characteristics in the initial phase of spool gap opening.•Determining axial and radial components of forces acting on the spool.•Making additional notches at the apex of the main operating grooves.•Improving flow characteristics with simultaneous reduction in resistance forces.
Due to the large energy consumption as well as poor controllability and other problems, the traditional cooling system has not been able to adapt to the development needs of construction machinery ...with the continuous upgrading of emission regulations. This paper introduces a hydraulic driven fan cooling system based on pilot operated electro-hydraulic proportional valve. In order to make the whole machine quickly reach the temperature required in the best working condition when the construction machinery starts working, controlling the fan at a lower speed can reduce the heat dissipation and save energy. The electronic control system will adjust the motor speed in time when the temperature of the fluid rises, and control the temperature in the best temperature range required. A one-dimensional simulation model of this stepless speed control system is established to predict the parameter sensitivity of the electro-hydraulic proportional valve and the dynamic performance of the system. The simulation shows that the fan speed of the system can reach the required speed in only 5s at the extreme high temperature of 40 °C; the fan input power of the system accounts for 65% of the system input power at −30 °C and reaches 80% at 40 °C. Three-dimensional simulation shows that the fan-front temperature-controlled cooling system for forklift truck has high heat dissipation efficiency and can be applied to other heavy machinery products.
•A hydraulic driven cooling system simulation model is developed.•Parameter sensitivity with pilot relief valve is analyzed.•Dynamic behavior of the system at extreme temperatures is predicted.•Heat transfer efficiency of the system is improved.•Thermal equilibrium temperature is well controlled.
•Effects of cavitation upon a proportional directional valve are investigated.•A very accurate full 3D mixture model is employed to predict cavitation.•The reduction in the flow rate and the change ...of the driving forces are quantified.•The zones where cavitation occurs are identified.•The incipient cavitation number is calculated.
This paper evaluates the effects of cavitation upon the performance of a hydraulic, proportional, directly-operated, directional valve by means of thorough experimental and numerical investigations. The experimental campaign is performed to estimate how cavitation changes the performance curves of the valve; in particular, the experimental equipment assembled to control the cavitation phenomenon inside the proportional valve is described, and the influence of cavitation on the flow rate and the flow coefficient as a function of the spool position is assessed. In addition, a full three-dimensional mixture model of the flow field within the valve is developed to accurately predict cavitation within the flow path for several spool positions. The accuracy of the numerical model is proven by previous experiences and by comparing the numerical results with the experimental data. After their validation, the numerical predictions are employed to analyse the characteristics of cavitation that cannot be experimentally evaluated, such as the volume of vapour, and to identify the zones where cavitation occurs. The numerical simulations are finally employed to predict how the variation in cavitation intensity influences the driving forces required to move the sliding spool and to calculate the minimum cavitation number for which the effects of cavitation are negligible.
In this paper, attention was focused on identifying the components of the amplitude-frequency spectrum of pressure pulsations in a hydraulic system in which an external low-frequency mechanical ...vibration was subjected to a proportional hydraulic directional control valve. It was observed that an operating machine or device equipped with hydraulic valves is a source of mechanical vibrations with a wide frequency spectrum. The influence of these vibrations on the pressure pulsation spectrum was analyzed, identifying the components resulting from the forcing of the directional control valve spool. In addition, it was noted that the pressure pulsation spectrum includes components resulting from the pulsation of the displacement pump output feeding the hydraulic system. A description of these spectrum components was also made and, using the solution superposition method, the components of the pressure pulsation spectrum over a wide frequency range were identified.
This paper presents a novel two-dimensional maglev servo proportional cartridge valve (2D maglev valve), where a contactless maglev coupling is introduced between electro-mechanical converter and ...valve body to realize functions of force transmission, spool position feedback and linear-rotary motion conversion. Such configuration can effectively reduce cost of both valve manufacturing and electro-mechanical converter, while still maintain features of 2D valve such as null pilot leakage, high power-to- weight ratio and excellent anti-pollution capacity. Firstly, the characteristic equation of the valve is derived using linear theory, and the stability criterion is established for parameter determination. The influences of crucial structural parameters such as initial height of overlapping area, width of high-pressure and low-pressure holes, acting radius of magnetic force, pitch angle of maglev coupling, length of sensitive chamber and system pressure on the dynamic response are investigated based on AMESim numerical simulation. The prototype valve is then designed and manufactured and a special test rig is built. The no-load flow characteristic, load flow characteristic, leakage characteristic, amplitude and phase frequency characteristics and step response under different system pressures are measured. The experimental results are in a good agreement with the simulated analysis. As an over-damped system, the prototype valve has excellent working stability, which can reach a no-load flow rate of 105.9 L/min with hysteresis of 3.51%, amplitude bandwidth of 28.7 Hz and phase bandwidth of 42.8 Hz under 21 MPa. The research indicates that the 2D maglev valve can be a potential solution of flow rate control valve for flight control surface system of civil aircraft with high pressure and large flow rate application.
The gas proportional valve (GPV) is a pneumatic pressure regulator, and the change in operating pressure will directly affect the opening and closing condition of the spool. In this study, the ...procedure for opening the spool is studied. The process of regulating the pressure of the GPV is revealed by the dynamical simulation method. The characteristics of displacement, total pressure and velocity of the spool during opening are analyzed. As time increases, it is found that the turbulence in the downstream of GPV becomes more obvious. In the process of spool movement, the influence of different inlet working pressures on spool displacement is analyzed. With a full open time of less than 1.5 × 10^ (−2) s, the spool reaches the stable state of full opening. In addition, the transient process of outlet flow is also studied. The simulated outlet flow is stable at 152 m3/h for the maximum opening. In order to verify the simulation results, the test of valve flow is carried out on the test bench. The results show that these methods can reduce the design difficulty and provide a reference for further optimization and engineering application of GPV.
•The dynamic numerical simulation of GPV is carried out by CFD.•The force of the spool opening process is analyzed by mathematical method.•A UDF program is developed to simulate the transient opening process of spool.•The influence of pressure variation on spool opening is analyzed by transient process.•The outlet flow of GPV is analyzed by transient process.
This article discusses the dynamic behavior of a spool plunger with a modernized drive. Modernization of the drive consists in replacing the electromagnet with a stepper motor with the transformation ...of rotational motion, — with the help of a screw pair, — into a rectilinear one. The contact between the ends of the screw and the plunger is provided by a spring. The value of the preliminary compression of the plunger to the end of the screw is assigned on the basis of guaranteed operation without loss of contact, due to which the plunger practically does not respond to disturbances and is devoid of an oscillatory component during the transient process. The mathematical model includes the influence of fluid friction and hydrodynamic force arising from pressure loss on the distributor 4 MPa. The study of the dynamics of the plunger consists in the accelerated retraction of the screw — which is in force contact with the end face of the spool — and the determination of the limit values of acceleration as a function of the preload force.
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