Piezoelectric ceramics are functional materials that convert electrical energy into mechanical energy, and vice versa. Piezoelectric proportional flow valves, driven by piezoelectric bimorphs, offer advantages such as fast response, low power consumption and high precision. However, the low output force of piezoelectric bimorphs limits their application in high-flow applications. To improve the output flow rate of the piezoelectric bimorph-driven proportional valve, we use ANSYS and COMSOL software to create three-dimensional and two-dimensional axisymmetric models of the piezoelectric valve and bimorph. The flow field characteristics of the valve and the fluid-structure coupling behavior of the piezoelectric element are analyzed. The effects of inlet and outlet positions, valve opening and chamber pressure on the output flow rate are also explored. The relationship between the force at the end of the piezoelectric bimorph and the output flow rate is studied, and its performance is compared with existing piezoelectric proportional valves of the same type. The results show that the optimized parameters significantly improve the valve's output flow rate. When the valve chamber's inlet pressure reaches 0.5 MPa (with an outlet radius of 1.1 mm), the output flow rate approaches 160 L/min, while the force on the free end of the piezoelectric bimorph is only 0.9 N. It provides guidance for designing nozzle-baffle pneumatic piezoelectric proportional valves and is expected to expand their application range.

We try to further reduce the energy consumption of the boom system driven by a multi-chamber hydraulic cylinder in hydraulic excavators, while also achieving a lightweight design of the cylinder. The effect of the area ratio on system energy consumption is first investigated. Then, the Non-dominated Sorting Genetic Algorithm Ⅱ is used to optimize the key structural parameters. The results show that when the area ratio of the rodless chamber to the energy storage chamber is between 1.0 and 1.1, the energy consumption of the excavator boom over one working cycle is the lowest. After optimization, the maximum stress of the multi-chamber hydraulic cylinder drops by 35.16%, and the overall weight decreases by 21.72%. In addition, the energy consumption per working cycle is reduced by 7.31% compared with that before optimization.

For a flat valve under rotating conditions, experimental and numerical methods are used to investigate the flow coefficients and their variation laws under rotating and non-rotating conditions for both forward and reverse flows. The results show that the flow coefficient is proportional to the valve port overlap and inversely proportional to the opening height. This effect weakens as the rotational speed and valve opening increase. Under rotating conditions, centrifugal force dominates the flow behavior. For forward flow, the flow coefficient increases with rotational speed, whereas it decreases for reverse flow. The Coriolis force breaks the axisymmetric inlet velocity distribution and counteracts the centrifugal effect within the flow-control region. As a result, the forward-flow coefficient decreases with increasing discharge velocity, while the reverse-flow coefficient increases. The variation of the flow coefficient is jointly characterized by the rotational Reynolds number and the discharge Reynolds number. At high rotational Reynolds numbers (about 93000) and high discharge Reynolds numbers (about 5500), the flow coefficients converge to 0.72~0.73 for forward flow and 0.52~0.53 for reverse flow. At a constant discharge Reynolds number, increasing rotational speed raises the forward-flow coefficient above 0.73 and reduces the reverse-flow coefficient below 0.52. At a constant rotational Reynolds number, increasing discharge velocity drives both coefficients toward the stable values under non-rotating conditions (approximately 0.57~0.65).

O-ring reciprocating seal structures are adopted for the sealing rings of hydraulic support valves. The sealing performance of O-rings determines the reliability of the valve-controlled cylinder system of hydraulic supports. O-ring seal failure can cause fluid intermixing and leakage inside hydraulic valves, and lead to failures in the normal opening and closing of hydraulic valve working ports and poor attitude control of hydraulic supports. Water-based emulsion serves as the medium for hydraulic supports, and its concentration affects the sealing effect. To explore the optimal concentration for different working conditions, a simulation analysis of the reciprocating friction force under various working conditions is conducted by combining finite element analysis and numerical calculation. To validate the simulation results, an experimental device is designed and built to measure the friction force of sealing rings in reciprocating seal structures of hydraulic systems. Based on this novel experimental device, the variation law of valve core reciprocating friction force affected by working condition factors under different medium concentrations is investigated, and thus the optimal medium concentration and friction control compensation strategy under fluid pressure fluctuation are determined.

Electro-hydraulic proportional pressure-reducing valves are core components in the electro-hydraulic control systems of construction machinery. Their performance degradation directly affects system reliability, and erosion wear is one of the primary failure modes of such valves. Taking a typical proportional pressure-reducing valve as the research object, we adopt computational fluid dynamics and the Discrete Phase Model and combine with the Oka erosion model, to simulate the fluid-solid two-phase flow characteristics and erosion wear distribution inside the valve under different spool clearances, opening degrees and inlet-outlet pressure differentials. The rationality of the simulation results is verified through experiments. The study shows that erosion wear mainly concentrates on the throttling edge region of port P; the wear rate peaks at a spool clearance of approximately 15 μm and a pressure differential of 2.8 MPa; as the clearance continues to increase or the pressure differential further rises, erosion wear exhibits a decreasing trend. Valve port erosion leads to reduced pressure gain and increased internal leakage, which is the main cause of performance degradation. This research provides a theoretical basis for the failure analysis, life prediction and structural optimization of proportional pressure-reducing valves.

In anchor drilling rig support operations, optimizing drilling parameters according to varying rock hardness is essential for improving drilling efficiency and ensuring operational safety. This study proposes an adaptive rotary drilling control system based on single-neuron PID control, enabling dynamic adjustment of drilling parameters in response to changes in rock hardness. The hydraulic system of the anchor drilling rig is designed, with key components calculated and selected. Using an AMESim-Simulink co-simulation platform, an electro-hydraulic simulation model is developed. Under varying rock hardness conditions, a comparative analysis is conducted between conventional PID control and single-neuron PID control strategies. Results indicate that the single-neuron PID control reduces steady-state error, shortens adjustment time, and minimizes overshoot compared to conventional PID. The optimized electro-hydraulic system with single-neuron PID achieves accurate, rapid, and stable adaptive drilling control in response to rock hardness variations, thereby enhancing the automation level of hydraulic anchor drilling rigs.

The reliability of hydraulic turbine governors directly affects the safe and stable operation of generating units, in which hydraulic control valves serve as important components. To improve the accuracy of reliability assessment for hydraulic control valves, a Copula-based method is proposed. Considering the randomness and non-monotonicity of performance degradation, the Wiener process is adopted to model two key performance characteristics. The bayesian information criterion is used to select the most suitable Copula function for describing their correlation, and a bivariate correlated degradation model is established. A case study based on full-life testing of electromagnetic directional valves shows that the proposed method can more comprehensively reflect the actual degradation state compared with univariate and bivariate independence assumption degradation models. The method provides more reasonable and accurate reliability assessment results with higher prediction credibility, and offers a more reliable basis for maintenance decision-making in hydropower stations.

Automatic weighing of excavator's material is essential for improving truck loading efficiency and enabling intelligent operation management. However, existing weighing methods often rely on multiple external pose sensors to obtain complete joint information of the working mechanism, which leads to high system costs, reduced reliability and difficulties in retrofitting. To overcome these limitations, we propose a data-driven “soft sensor” technique that uses only standard hydraulic cylinder pressure sensors and boom inclination sensors already standard on excavators to achieve real-time collaborative estimation of material weight and key poses during operation. By extracting dynamic features from specific operational phases, the method simplifies complex pose variations into slowly changing parameters. It employs a constrained nonlinear least squares fitting strategy to accurately estimate both material weight and stick position/orientation. These estimates are then used as known inputs to inversely derive the complete bucket pose. The results from simulations and field tests confirm that estimation errors for material weight and key pose parameters are within 3%. This approach provides an efficient and practical solution for automatic weighing systems and establishes a precise pose reference for enabling automated functions such as trajectory tracking, demonstrating strong potential for industrial applications.

During the transition of a stepper motor direct-drive slide valve from zero to maximum opening, the electromagnetic torque of the stepper motor is required to reliably balance the holding torque at each operating point of the slide. Under constant-current control, the electromagnetic torque of the stepper motor decreases with increasing temperature, and dead zones and saturation regions exist in the relationship between electromagnetic torque and motor current. These factors prevent accurate matching between electromagnetic torque and the holding torque at slide operating points. To address this problem, based on the current-electromagnetic torque characteristics of the stepper motor and slide mechanical theory, the torque constant is identified as the key parameter affecting the torque balance. An experimental scheme for torque constant identification is designed. Linear regression is applied to fit the current-electromagnetic torque characteristic curve. The torque constant K_t is identified as 0.413±0.01 N·m/A, and the linear current range is 0.4~2.3 A. Static torque thresholds at spool operating points are tested to ensure reliable valve operation under hydraulic force limits. Finally, a current-displacement matching method based on holding torque parameters within the linear torque range is proposed. Experimental results show that, compared with conventional constant-current control, the proposed method achieves lower motor energy consumption.

Calculation of the jet flow force on the deflector plate is fundamental for torque motor design, determination of the static operating point of the armature assembly and performance analysis of the servo valve. To address the difficulty in theoretical modeling and analysis of the jet flow force on the deflector plate, we develop a three-dimensional steady-state magneto-solid-fluid multi-physics coupling simulation model for the deflector jet valve. Comparison between simulation results and experimental tests shows a maximum deviation of 8.9% for armature displacement and 9.6% for pre-stage blocking pressure characteristics, which validates the model. Based on this model, we further analyze the influence of control current and inlet pressure on output torque of armature, displacement and baffle jet force. Results indicate that the jet flow force reduces armature output torque of armature and displacement. A larger control current and higher inlet pressure lead to a more significant reduction in output torque of armature and displacement. Using simulation data at 4 and 6 MPa, we derive a binary functional relationship between the flow force and inlet pressure and control current, with a goodness of fit R²=0.9964. We use this fitted relationship to predict the flow force at inlet pressures of 2 and 8 MPa. Compared with simulation results, the maximum deviations are 7.7% and 2.4%, respectively. This work lays a foundation for subsequent analytical analysis of static and dynamic characteristics of the servo valve.

Pressure-loss braking systems are widely used in mining vehicles. To understand the static characteristics of the brake valve, which is a core component in the brake system, and to improve the design theory of the brake system, a static mathematical model of the brake valve is established based on a detailed analysis of its structure and working principle. With different pedal forces as inputs, the variation law of the static braking pressure of the brake valve is studied, and the influence law and sensitivity of the main structural parameters of the brake valve on both the braking pressure and the maximum braking pressure are revealed. Finally, the theoretical calculation model is validated by using a full-vehicle braking system as the experimental platform. The results show that the static braking pressure of the brake valve is constrained by multiple factors. When the pedal force increases to a level sufficient to initiate pressure release, the braking pressure varies linearly with the pedal force. The greater the pedal force, the lower the braking pressure, but the maximum braking pressure is only related to the structural parameters of the brake valve. The sealing length, bias spring stiffness, and pressure regulating spring stiffness have a significant impact on the static characteristics of the brake valve, while the spool diameter and pressure regulating spring stiffness have a notable effect on the maximum braking pressure.

To address the insufficient adaptability of traditional infrared camouflage technologies in dynamic complex environments and multispectral detection, a microfluidic-based infrared camouflage film system is proposed for the adaptive matching of target and background infrared signatures through real-time thermal radiation regulation. A thermal-fluid-structure coupling simulation model comprising a solid substrate and embedded microchannels is established to analyze steady-state heat transfer characteristics. Simulations are performed with inlet flow velocities ranging from 0.25 to 5.00 m/s and channel spacings from 1 to 4 mm to determine the effects of flow velocity and structural parameters on temperature distribution. The surface temperature variations are verified through infrared imaging tests under various flow velocities and time sequences. The results indicate that higher flow velocities (e.g., 5.00 m/s) and smaller channel spacings (e.g., 1 mm) significantly improve temperature uniformity, with the maximum temperature difference reduced from 15 ℃ to 2 ℃, thereby blurring the target's infrared contour. At flow velocities exceeding 0.50 m/s, the film surface temperature converges rapidly with the background, achieving effective infrared concealment.

Aimed at the issue that pilot-operated gas safety valves are prone to flutter under specific operating conditions, which affects the stable operation of the system, a systematic study on the flutter mechanism and suppression strategy is conducted by combining mathematical modeling and frequency domain analysis. Firstly, based on the internal flow characteristics and structural dynamics, the motion processes of the pilot valve and the main valve are decoupled and analyzed, and dynamic models incorporating aerodynamic force, elastic force and damping terms are established respectively. On this basis, frequency domain analysis reveals that insufficient phase margin of the main valve under pilot control is the main cause of flutter. MATLAB simulation results indicate that introducing a damping orifice of appropriate size into the original system structure can effectively increase system damping and improve the phase margin of the main valve, thereby significantly suppressing the flutter tendency. Meanwhile, appropriately increasing the initial opening of the main valve also helps to improve the system's dynamic characteristics. Further experimental verification shows that the stability and dynamic response performance of the improved pilot-operated safety valve are significantly enhanced, and the flutter phenomenon is effectively suppressed. The research results provide theoretical basis and engineering reference for the structural design and parameter optimization of pilot-operated gas safety valves.