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气门机构动力学模型中液压间隙调节器(HLA)的模拟 总被引:5,自引:1,他引:5
在气门机构动力学计算中,模拟液压间隙调节器(HLA)应考虑到高压腔机油的可压缩性、泄漏及补偿;同时也应考虑泄漏机油对柱塞和柱塞套的剪切阻尼力的影响。介绍了国外研究的液压模型和质量-阻尼-弹簧模型,从物理意义上对质量-阻尼-弹簧模型以及其中刚度、阻尼参数的聚值进行了分析和探讨。 相似文献
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液压气门间隙调节器研究中的泄沉试验方法 总被引:1,自引:0,他引:1
利用泄沉试验得出的HLA泄漏流量与其受力的关系,可算出HLA弹簧—阻尼模型中的阻尼系数;将HLA泄沉试验结果与另外进行的气门机构动态测量的结果相结合,可估算出HLA高压腔机油混气量。以一个直动式HLA及其气门机构为例,以HLA泄沉试验的目的、方法及对试验结果的处理分析为主要内容,介绍了确定阻尼系数和机油混气量这两个参数的意义和实现方法。 相似文献
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(续上期)
四、液压挺杆可能带来的问题
1.对气门传动链刚度的影响
气门传动链的刚度直接影响气门传动链的振动和噪声.刚度下降可能导致噪声的增加.整个气门传动链的刚度取决于气门传动链中刚度最低的环节.在采用液压挺杆的气门传动链中,刚度最低的环节就是液压挺杆高压腔里的机油.这部份机油的刚度跟机油的弹性模量成正比,并且跟高压腔的几何形状有关.在机油中含有大量未溶解的空气的情况下,提高高压腔内机油的压力可以提高机油的弹性模量.同时,气门传动链的刚度还跟液压挺杆的液压长度,也就是高压腔中机油压力传递路径的长度成反比.液压长度应当尽可能地小.…… 相似文献
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(三)气门机构
1.概述
气门机构由液压挺杆,滚针式摇臂和双VVT-i系统组成,如图10所示.
通过机油压力和弹簧使气门间隙保持为0,如图11所示.
发动机机油更换步骤:
(1)使用专用工具按下单向球,如图12所示.
(2)将液压挺杆浸入干净的机油中,使用专用工具反复按下柱塞5~6次,如图13所示. 相似文献
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气门机构中的液力间隙调节器 总被引:2,自引:2,他引:2
现代汽车发动机,尤其是轿车发动机,已普遍采用液力间隙调节器的气门机构,根据国外的有关文献,阐述了HLA的结构形式,工作原理,采用HLA的优点和可能存在的总是并对HLA的设计特点,检验项目和检验方法,以及对其某些特性的研究进行了介绍。 相似文献
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气门机构的不正常振动是高性能四冲程发动机设计者面临的一个长期未能解决的问题。如果能用某种分析分法对发动机气门机构的运动状态进行预测,可以缩短发动机研制时间,降低费用。本文叙述了单列顶置凸轮式(SOHC)和双列顶置凸轮式(DOHC)两种气门机构通过交互式的计算和使用计算机绘图来进行气门运动模拟的一种方法。作者试图用模态分析法和模型化技术建立尽可能简单的模拟模型。通过调整模拟模型参数和由试验确定阻尼因数,使计算结果和实测结果非常接近。 相似文献
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In an HLA (hydraulic lash adjuster) piston engine, “pump up” can occur when a valve is opened by the HLA when it should be
closed. HLA pump up is more frequently encountered with exhaust valves than with intake valves. When HLA pump up in occurs
in the exhaust valve, exhaust gas from the exhaust manifold enters the cylinder on the intake stroke, and fresh air-fuel mixture
exits through the exhaust manifold on the compression stroke and is burned in the catalyst, causing partial burning, misfire,
catalyst melting and power drop. HLA pump up occurs when the force on the valve from the HLA is higher than the force on the
HLA from the valve. HLA pump up is related to design parameters, such as oil pressure, rocker ratio, spring load, spring surge,
and both intake and exhaust valve timing. In this study, valve lift and load on a roller finger follower were measured at
varying engine firing conditions to evaluate HLA pump up. The results indicated that effective measures to reduce HLA pump
up include a higher rocker ratio, a lower oil supply pressure to the HLA, a higher spring installation load and a lower spring
surge. 相似文献
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Jingyu Choi Kyunggook Bae Junbeom Wi Sunghyun Ahn Hyunsoo Kim 《International Journal of Automotive Technology》2018,19(1):147-157
In this paper, a design method for a PHEV hydraulic control system was proposed considering motor thermal management. Dynamic models of the target PHEV were developed including the hydraulic system, which consists of one mechanical and one electric oil pump. The required motor cooling flow was designed based on the motor temperature, which was obtained from a one-dimensional thermal equivalent circuit model including the heat source and oil spray cooling. Combining the PHEV powertrain model, hydraulic control system model, and the motor thermal model including the cooling system, an integrated simulator was developed for the target PHEV. Using the integrated simulator, the temperatures of MG1 and MG2 were investigated for various motor cooling flow rates when the PHEV underwent a highway driving cycle. The energy consumption of the hydraulic control system was also evaluated. It was found from the simulation results that a hydraulic control system of the target PHEV could be designed that satisfied the required flow for the motor cooling, lubrication and brake control using the design procedure proposed in this study. 相似文献
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Hongpeng Zheng Yulong Lei Pengxiang Song 《International Journal of Automotive Technology》2017,18(3):387-396
Hydraulic retarders are auxiliary braking devices that reduce the velocity of a vehicle, particularly when a vehicle is driven downhill. Such velocity reduction could reduce the potential risk caused by brake failure caused by the service brake working for a long time and the temperature of the brake shoe becomes extremely high. This paper introduces the construction of the hydraulic retarder and proposes two mathematical models for the hydraulic retarder. The first mathematical model is deduced by using fluid mechanics, which is used to analyze the mechanism of how braking torque is produced and the key factors that can influence the value of the braking torque. The second mathematical model is deduced by using thermodynamics, which is used to quantify the heat produced by the hydraulic retarder. This research emphasizes that the flow rate and the average velocity of the working fluid in the working chamber mainly determine the braking torque of the hydraulic retarder. The flow rate into and out of the working chamber determines the temperature rise of the working fluid. Computational fluid dynamics (CFD) simulations are conducted with the Reynolds-averaged Navier-Stokes (RANS) and Shear Stress Transport (SST) turbulent models. Experiments are carried out to justify the two mathematical models and the CFD simulations. The results show that the mathematical models are capable of describing the force analysis and energy conversion of the hydraulic retarder and SST is more accurate for CFD simulation and the error is within 6 %. 相似文献
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为解决传统湿式双离合器变速器 (Dual Clutch Transmission, DCT) 控制策略在硬件误差以及复杂工况下液压响应预测精度不完全可控的问题,提出了一种基于 SHAP 图可解释极端随机树预测模型,使用机器学习方法结合某汽车公司 DCT 实验室采集的真实离合器数据对 DCT 液压响应进行预测。模型利用 SHAP 算法对于重要特征选择的可解释性,筛选并保留对液压响应影响较大的特征,将时间切片和升降压判定作为特征加入训练数据,训练预测模型。结果表明,该模型训练结果的均方误差 MSE 为 0.670 3,可决系数 R2为 1.000 0,并且在测试集上预测值与实际值之间的平均误差为12.99 kPa,远低于设计误差 25 kPa,具有较高的预测精度,特征选择较准确,可以很好地解决传统物理模型无法计算不同工况下液压响应的问题,为下阶段基于数据和物理双驱动的DCT控制策略优化提供较准确的预测结果。 相似文献
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本文在理论上建立了一套基于主动力反馈原理的新型主动阻尼悬架的设计和优化方法。首先提出了该主动阻尼悬架的实现模型,该模型是在传统的液力减振器的基础上,应用半主动控制的思想,结合力反馈的原理建立起来的内部液压反馈阻尼网络模型。理论优化分析和计算机仿真表明,通过该液阻网络模型,即可以实现电控的主动阻尼悬架的功能,它可以根据汽车行驶路况的好坏,自适应地调节悬架阻尼大小以实现主动阻尼悬架的最优控制。 相似文献