The hydraulic spool valve (HSV) represents the core control element in the fluid power system by virtue of its precise flow and pressure regulation abilities. Unbalanced radial flow force (RFF) is a major contributor to spool instability and friction-induced failure in HSVs, particularly in open-neutral configurations where flow field asymmetry is prominent. Conventional assumptions often overlook RFF due to structural symmetry, yet practical designs constrained by standard port layouts frequently induce asymmetrical pressure and velocity distributions. To address this issue, a novel through-hole design is proposed and integrated into the mid-shoulder of the HSV spool. Specifically, the study employs a combined approach of computational fluid dynamics-based numerical simulations and experimental bench testing to evaluate RFF generation and suppression mechanisms. The Realizable k–ε turbulence model is used to capture turbulent flow features and assess the contribution of pressure and viscous forces. Various through-hole angles are analyzed to determine the optimal configuration. Results indicate that RFF is predominantly pressure-driven (accounting for over 85% of total force), with significant asymmetries localized around the mid-shoulder region. Incorporating a 15° inclined dual through-hole structure reduces RFF on the mid-shoulder by 45.5% and total spool RFF by 29.9%, improving flow symmetry and minimizing pressure gradients. The optimized structure also enhances performance stability under varying spool displacements, achieving a maximum total spool RFF reduction of 55.5% at −1.5 mm displacement.

As the ‘heart’ of energy vehicles, the lithium-ion battery is in desperate need of precision improvement, green production, and cost reduction. To achieve this goal, the electro-hydraulic servo pump control system (EHSPCS) is applied to the lithium-ion battery pole rolling mill (LBPRM). However, this development can lead to limited dynamic performance and large power loss as a result of the EHSPCS unique volume direct-drive control mode. At present, how to solve this conflict has not been studied and how the EHSPCS component parameters influence the dynamic response, power loss, and economic performance is not clear. In this paper, a multi-objective optimization (MOO) model for the LBPRM-EHSPCS is proposed by comprehensively considering the dynamic, efficiency, and economic characteristics. Firstly, the evaluation model of the dynamic response, power loss, and cost is investigated. Then, the NSGA-II algorithm is introduced to address the Pareto front of the MOO model. Finally, the power loss and dynamic response of the LBPRM-EHSPCS before and after optimization are tested to validate the viability of the raised method. Results indicate that power loss is decreased by as much as 7.2% while steady-state precision is greatly improved after optimization. The proposed framework enhances the performance in lithium-ion battery manufacturing and can be applied to other kinds of hydraulic systems.

Facing the development trend of electrification of construction machinery, in view of the drawbacks of the existing electro-hydraulic-load-sensitive system in terms of dynamic characteristics and usage of energy, based on the drive source of a servo motor-driven quantitative pump, an electro-hydraulic-load-sensitive system on the basis of torque open-loop control was proposed. Firstly, the working principle of the system was introduced and the system’s operating characteristics and energy consumption characteristics were theoretically analyzed. Secondly, in order to balance the system’s energy usage and maneuverability, a control strategy with a variable pressure margin was designed. Meanwhile, in order to solve the problem that the hydraulic pump’s mechanical efficiency causes system pressure control deviation, a torque compensation method based on offline data and speed prediction was proposed. Finally, simulation and testing were used to confirm the viability of the control strategy. The test results show that: the system could realize stable pressure margin control, and the response rise time was within 0.7 s under a variety of flow circumstances; the system could follow the control instruction to change linearly and the flow rate changed smoothly in the adjustable pressure gap control; after using the compensation method, the deviation of the pressure gap control was within 2%.

1. Hydraulic actuation systems remain indispensable in aerospace, construction machinery, and other high-power-density engineering applications owing to their superior load capacity, robustness, an...