Electric-controlled pressure relief valve for enhanced safety in liquid-cooled lithium-ion battery packs

The liquid-cooled battery energy sto rage system(LCBESS) has gained significant attention due to its superior thermal management capacity.However,liquid-cooled battery pack(LCBP) usually has a high sealing level above IP65,which can trap flammable and explosive gases from battery thermal runaway and cause explosions.This poses serious safety risks and challenges for LCBESS.In this study,we tested overcharged battery inside a commercial LCBP and found that the conventionally mechanical pressure relief valve(PRV) on the LCBP had a delayed response and low-pressure relief efficiency.A realistic 20-foot model of an energy storage cabin was constructed using the Flacs finite element simulation software.Comparative studies were conducted to evaluate the pressure relief efficiency and the influence on neighboring battery packs in case of internal explosions,considering different sizes and installation positions of the PRV.Here,a newly developed electric-controlled PRV integrated with battery fault detection is introduced,capable of starting within 50 ms of the battery safety valve opening.Furthermore,the PRV was integrated with the battery management system and changed the battery charging and discharging strategy after the PRV was opened.Experimental tests confirmed the efficacy of this method in preventing explosions.This paper addresses the safety concerns associated with LCBPs and proposes an effective solution for explosion relief.

Effect of Dynamic Pressure Feedback Orifice on Stability of Cartridge-Type Hydraulic Pilot-Operated Relief Valve

Current research on pilot-operated relief valve stability is primarily conducted from the perspective of system dynamics or stability criteria,and most of the existing conclusions focus on the spool shape,damping hole size,and pulsation frequency of the pump.However,the essential factors pertaining to the unstable vibration of relief valves remain ambiguous.In this study,the dynamic behavior of a pilot-operated relief valve is investigated using the frequency-domain method.The result suggests that the dynamic pressure feedback orifice is vital to the dynamic characteristics of the valve.A large orifice has a low flow resistance.In this case,the fluid in the main spring chamber flows freely,which is not conducive to the stability of the relief valve.However,a small orifice may create significant flow resistance,thus restricting fluid flow.In this case,the oil inside the main valve spring chamber is equivalent to a high-stiffness liquid spring.The main mass-spring vibration system has a natural frequency that differs significantly from the operating frequency of the relief valve,which is conducive to the stability of the relief valve.Good agreement is obtained between the theoretical analysis and experiments.The results indicate that designing a dynamic pressure feedback orifice of an appropriate size is beneficial to improving the stability of hydraulic pilot-operated relief valves.In addition,the dynamic pressure feedback orifice reduces the response speed of the relief valve.This study comprehensively considers the stability,rapidity,and immunity of relief valves and expands current investigations into the dynamic characteristics of relief valves from the perspective of classical control theory,thus revealing the importance of different parameters.

PRESSURE COMPENSATION METHOD OF UNDERWATER HYDRAULIC SYSTEM WITH HYDRAULIC POWER UNIT BEING UNDER ATMOSPHERIC CIRCUMSTANCE AND PRESSURE COMPENSATED VALVE

Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems （UHSs）, a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumstance, is proposed. And a pilot-operated relief valve with pressure compensation is realized. The pressure compensation precision is guaranteed by direct detection. Its dynamic performance and stability are improved by a dynamic feedback. Theoretical study, simulation and experiment show that the pilot-operated relief valve with pressure compensation has a fine property of tracking underwater ambient pressure and meet the requirement of underwater ambient pressure compensation.

Analytical analysis of single-stage pressure relief valves

The article presents an explicitly straightforward formulation of the stationary and dynamic behaviour of a pressure relief valve (PRV). This includes an analytical solution for the static p-Q-characteristic, the step and harmonic response and a stability criterion using elementary operations only. It also mathematically proves the intrinsic connection between the gradient of the static p-Q-characteristic and the stability. Thus, the new method offers four main advantages.

Pressure Control of a Large-scale Hydraulic Power Unit Using π Bridge Network

The steady state and dynamic characteristics of pressure output of a hydraulic power unit are important to the hydraulic system behavior.Because of the compact structure,the B-half bridge resistance network is widely used in the pilot controlled pressure relief valves.However the steady-state pressure error might be unacceptably big in those pressure control systems.A constant pressure power unit is typically assumed in analysis of steady state and dynamic behavior of hydraulic systems.The flow-pressure relationship seems to be much complex,in particular when big flow variation takes place.In this paper,the π bridge hydraulic resistance network pilot stage is designed in order to get better flow-pressure characteristics.Based on the similarity of electrical circuits,the main factors influencing flow-pressure characteristics are analyzed.Moreover,the optimum diameters of both constant hydraulic resistor and dynamic resistor are proposed.Flow-pressure characteristics are compared with different constant hydraulic resistors,dynamic resistor and spring stiffness by simulations and experiments.Results of simulations and experiments show that flow-pressure characteristics depend very little on the spring stiffness in whole flow range.Good controlled pressure characteristics can be achieved with suitable constant resistors.Overshoot can be reduced with the small diameter of the dynamic resistor.Flow-pressure characteristics of pressure relief valve can be improved with a π bridge pilot stage.The proposed pressure control method will provide some positive guidelines and be helpful to design a high performance hydraulic system with large flow.

双膛石灰竖窑粉尘排放特性及控制技术研究

分析了石灰双膛竖窑在泄压过程中的粉尘排放特性,初始冲击波压力过高导致烟气无法直连布袋除尘器,这是造成粉尘污染的主要原因。弄清了初始冲击波的形成、传播与演化行为特征,比对了延长直管长度、增加弯管数量、增加变径结构与泄压腔体三种方式对冲击波压力的衰减效果,提出了一种基于压块泄压阀的柔性泄压直联布袋技术,将放散烟气初始冲击波压力由8 kPa降至1 kPa,达到烟气直连布袋、环境粉尘污染得到大幅改善的效果。同时,针对粉尘在阀体和管道中易沉降的难题,提出了一种基于3通内旋阀的扇形旋塞防沉降技术,解决了粉尘在阀体与管道系统内的沉降难题。

博世共轨压力泄压阀打开故障解析

文章主要对泄压阀的结构原理、故障发生机理进行系统介绍,并结合故障诊断与排除思路进行说明,以期能够为维修人员提供一些启发和帮助。

振动环境下直动式溢流阀的防压力波动可靠性分析

液压装备工作环境复杂,其中不乏存在振动、冲击等不利因素,这些因素与不确定性因素耦合极易引起溢流阀调定不当从而造成液压装备失效。针对此问题,考虑不确定性因素的影响,提出了一种直动式溢流阀防压力波动可靠性分析模型。通过适当简化建立了溢流阀在振动环境下的数学模型,并以调定压力波动幅值是否超过国标规定值为判别条件,构建了溢流阀压力波动失效的功能函数。考虑到功能函数为强非线性隐式,将MATLAB/Simulink仿真与主动学习Kriging模型相结合建立溢流阀防压力波动可靠性分析方法,并得到了振动环境下溢流阀压力波动失效概率。所得结果不仅为溢流阀的可靠性评估和设计优化提供了新的指导,还对发展液压相关元件可靠性技术具有一定的学术价值。

低背压条件下非能动泄压和再循环阀内部流动特性研究

为了获得低背压条件下非能动自动泄压阀内部流动特性。计算中使用计算流体动力学(CFD)方法建立了主阀的流道模型,得到了不同工况下各部位的单相以及两相流场分布,获得了主阀的阻力特性,为阀门的设计提供支持。

复合磁-电弹簧直动式溢流阀设计与性能分析

为了解决传统机械弹簧因塑性变形、断裂等造成溢流阀工作性能劣化的问题,设计一种复合磁-电弹簧结构应用于直动式溢流阀调压弹簧中,以提高直动式溢流阀的响应速度,实现电控弹簧力。理论分析复合磁-电弹簧磁力特性,利用Maxwell软件对复合磁-电弹簧进行磁力特性仿真;采用AMESim软件对机械弹簧直动式溢流阀和复合磁-电弹簧直动式溢流阀进行动态特性仿真。对复合磁-电弹簧磁力特性及溢流阀的动态特性进行实验测试。结果表明:复合磁-电弹簧设计合理,复合磁-电弹簧直动式溢流阀动态响应特性优于现有机械弹簧直动式溢流阀。

恒力磨床液压控制系统研究

为提高某恒力磨床设备的压力精度,增加对位置偏差干扰的抵抗能力,根据设备输出数据指标设计研究液压控制系统。根据设计的液压原理图在AMESim仿真软件中完成系统仿真建模,进行闭环压力控制系统分析研究,最终采用前馈补偿与压力闭环反馈结合的复合PID控制方案,具有最佳控制效果,并能够实现在工作过程中遇到位置偏差时具有一定抗干扰能力,保证输出精度在目标压力精度范围内。

蒸汽安全阀仿真分析与结构优化

采用ANSYS CFX流场仿真技术对优化后的锅炉管道用蒸汽安全阀流场排量和升力系数进行研究。结果表明:结构优化后的蒸汽安全阀开高设计合理,具有较好的排放性能,临界压力比在0.400~0.497之间,流阻损失小。阀瓣结构优化后,升力曲线得到改善,能够迅速达到设计开高要求,及时排放压力,减少颤振等问题的发生。

液压油箱卸压活门三参数威布尔寿命分布灰色建模

针对三参数威布尔分布参数估计的难题,提出一种三参数威布尔分布参数的灰色估计方法。基于某型液压油箱卸压活门使用阶段的随机截尾型可靠性数据,采用GM(1,1)估计三参数威布尔分布模型的参数。结果表明:应用灰色模型GM(1,1)能够估计出三参数威布尔分布的3个参数,避免了迭代过程,具有求解速度快、所需子样少、精度高、计算机编程方便等优点,同时也验证了三参数威布尔分布模型比两参数威布尔分布模型更为精确,可为武器装备在使用阶段提供一种更为精确的可靠性分析方法。

供氮气源装置膜片式泄压阀异常打开原因分析

介绍了某供氮气源膜片式泄压阀异常打开原因的排查过程,分析可能造成泄压阀异常打开的原因,并针对可能原因进行试验验证和排查,通过气候模拟、能谱对源区成分分析等方法,对排查中发现的具体问题进行具体分析,最终发现故障原因并得出结论。

LNG储罐压力安全阀泄放量的计算探讨

基于API和GB规范,对LNG储罐的泄放量计算方法进行总结并比较不同。分别对API和厂家指导手册就公制和美制单位下的储罐压力安全阀的泄放量计算方法进行详细介绍,拟合排放系数关于绝对压力比的计算公式,结果表明拟合公式计算结果与厂家计算值相近。基于某实际工程项目应用,将规范、指导手册、拟合公式计算结果相比较,结果具有较好的一致性。通过对不同规范及厂家标准的比较和计算,可增强工程设计人员对储罐和压力安全阀泄放量的进一步认识,并提供计算指导。

基于AMESim的高压溢流阀特性分析

先导式高压溢流阀作为轴向柱塞变量泵或轴向柱塞变量马达的安全阀,其工作性能将直接关系到轴向柱塞变量泵、轴向柱塞变量马达及系统的安全性与可靠性。针对某型高压溢流阀,对其进行工作原理介绍以及数学计算,并通过AMESim建立仿真模型,探究节流孔直径、先导弹簧预紧力和主阀弹簧预紧力对高压溢流阀的开启压力、压力超调量、压力超调稳定时间及卸荷时间的影响,对高压溢流阀的设计具有指导意义。

矿用乳化液泵站泵头供液流量匹配控制研究

供液流量匹配的精确控制有助于减少矿山作业设备因液压波动而出现的故障,为此研究比例溢流阀压力补偿下矿用乳化液泵站泵头供液流量匹配控制方法,以泵站泵头在一定时间内完成所有动作乳化液流量负荷波动率和消耗能源量作为目标函数,建立矿用乳化液泵站泵头供液流量匹配控制模型,设置模型约束函数后,利用遗传算法求解供液流量匹配控制模型,得出控制结果。实验表明:该方法计算比例溢流阀当前压力数值较为准确,可迅速对比例溢流阀压力进行补偿,同时可有效对乳化液泵站泵头供液流量进行匹配控制,应用效果较为显著。

DCS控制器中先导式泄压阀异常泄漏信号检测

在DCS控制器中,由于工作环境复杂,先导式泄压阀的泄漏往往呈渐进过程,其影响的电压信号表现为细微而持续的变化,传统方法基于静态或简单统计特征进行判断,难以捕捉因泄漏引起的微小动态变化,导致早期泄漏的漏检或误报。因此,提出一种针对DCS控制器中先导式泄压阀异常泄漏信号检测的新方法,对先导式泄压阀信号进行预处理消除噪声和干扰;应用变分模态分解(VMD)技术将预处理后的电压信号分解成多个本征模态函数(IMF)分量,揭示信号中不同频率段的特征,从而更容易捕捉泄漏引起的微小动态变化;从每个IMF分量中提取关键特征参数,并采用距离区分技术进行筛选,以确保所选特征对异常泄漏具有高敏感性和高区分度。设计并构建全卷积神经网络模型,将筛选出的特征参数输入该模型进行训练和学习,计算出该信号特征对应的异常泄漏概率,进而判断泄压阀是否存在异常泄漏,实现异常泄漏信号检测。实验结果表明:所提方法对电压信号分解准确率高,先导式泄压阀异常泄漏信号检测精度高。

压力释放阀性能试验中存在问题与对策分析

压力释放阀作为油浸式电力变压器的泄压防爆装置,是非电量保护系统中的关键设备之一。梳理了压力释放阀装置试验分类,分析了其关键性能参数,针对性能试验中存在的试验标准滞后、检测设备复杂且缺乏规范、例行试验不合格率偏高、开启时间检测难以实施、排量性能试验不完善等若干问题,进行了具体的原因分析及难点解剖,并提出了相应的处理措施及合理化建议。

某柴油机冷启动异响排查及优化方案

针对某机型柴油机出现的冷启动怠速异响问题,采用“主观评价—试验分析与仿真分析相结合—试验验证”的NVH分析方法,确定该机型柴油机冷启动异响问题是由于机油泵阻尼孔直径设计过大,导致机油泵泄压阀阀芯进入超调失稳振动状态,进而引起冷却系统零部件声振响应。对机油泵进行仿真分析并进行试验验证,结果表明适当调整阻尼孔尺寸可消除该机型柴油机的冷启动怠速异响问题。