共查询到20条相似文献,搜索用时 15 毫秒
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在柴油机强化设计过程中,曲轴的不平衡惯性力会引起轴颈倾斜加剧,因此研究平衡率对曲轴振动和主轴承、连杆轴承润滑特性的影响尤为必要。基于含机油填充率的平均Reynolds方程、Greenwood-Tripp粗糙接触和平衡率计算理论,计入表面粗糙度和弹性变形等因素的影响,以12V150柴油机为例分析不同平衡率对曲轴润滑与振动特性的影响。结果表明:在一个工作循环内,随着平衡率的增加,主轴承和连杆轴承的最小油膜厚度在大部分时间内均有所增加,最大油膜压力和摩擦损失功在大部分时间内均有所减小,而主轴颈和连杆轴颈水平弯曲振动和自由端扭转振动在大部分时间内整体减小;在高功率密度柴油机曲轴轴承润滑设计及振动控制中,应综合考虑曲轴平衡率的影响。 相似文献
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Kh. Zaheeruddin 《Wear》1981,71(2):139-152
The generalized Reynolds equation governing the pressure distribution for a micropolar lubricant in a dynamically loaded porous journal bearing is derived and applied to one-dimensional squeeze film journal bearings operating under a cyclic load. The analysis indicates how the microstructure in the lubricant, the permeability of the bearing material and the bearing wall thickness influence the operating eccentricity ratio. 相似文献
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Hou Yu Chen ShuangtaoChen Rugang Zhang QiaoyuZhao Hongli 《Tribology International》2011,44(9):1061-1070
A numerical model coupling the hydrodynamic pressure of lubricant film with the deformation of foil structure was developed for a type of foil journal bearing with protuberant foil structure. An isothermal and isoviscous lubricant was used in the fluid model, and a perturbation method was applied to linearize the Reynolds equation. The top foil was modeled as a strip of rectangular thin plate supported at a rigid point. The distributions of film pressure, film thickness, and foil deformation were solved by the finite element method (FEM). The effects of eccentricity ratio, bearing number, and number of protuberances on the characteristics of bearings were analyzed. 相似文献
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In this article a numerical investigation of a connecting rod bearing operating at 6,500 rpm is performed. This is a companion to an earlier article that took into account the effects of the inertial force and the variable bolt tension force, which are considered to be the principal factors that affect the connecting rod bearing lubrication characteristics of an engine running at high speed. It was found that a thinner minimum oil film and a larger peak hydrodynamic pressure are predicted in a deformed connecting rod bearing than in a rigid connecting rod bearing. Multi-peaked hydrodynamic pressure was found to appear as well because of two or more converging-diverging film regions. 相似文献
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内燃机连杆轴承的润滑状况对连杆轴承的使用寿命影响很大。随着内燃机的不断强化,对连杆轴承性能的要求也相应提高。因此,深入研究连杆轴承的润滑问题以便更加准确地分析和设计轴承的性能便显得日益重要。首先从理论上阐述了润滑状况对轴承工作可靠性的影响,然后针对某发动机的连杆,在AVL-EXCITE中建立了连杆的柔性多体动力学与动力润滑耦合仿真模型。通过计算得到了连杆轴承的轴心轨迹、最小油膜厚度和最大油膜压力等参数,并比较了转速、轴承间隙和温度对轴承润滑性能的影响。研究结果对连杆轴承动力学耦合分析和优化设计以及判断轴承工作的可靠性具有重要意义。 相似文献
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Lubrication performance of finite journal bearings considering effects of couple stresses and surface roughness 总被引:1,自引:0,他引:1
To inspect the performance characteristics of finite journal-bearing systems, the combined effects of couple stress due to a Newtonian lubricant blended with additives and the presence of roughness on journal-bearing surfaces are studied in this article. Basing on the Stokes theory and Christensen’s stochastic model, the stochastic generalized Reynolds equation is deduced. The film pressure distribution equation is numerically solved by using the conjugate gradient method of iterations. According to the results, the couple stress effects can raise the film pressure of the lubricant fluid, improve the load-carrying capacity and reduce the friction parameter, especially at high eccentricity ratio. The surface roughness effect is dominant in long bearing approximation and the influence of transverse or longitudinal roughness to the journal bearing is in reverse trend. In general, the critical value of length-to-diameter is 1.1. 相似文献
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This study deals with the development of a computational procedure for solving the isothermal compressible Reynolds equation as the governing equation of air-bearing analysis. Newton's method is used to linearize Reynolds equation and an iterative successive relaxation process is adopted to solve for the air film pressure. The optimal value of relaxation factor for the cases studied is suggested in this report for numerical stability and computational efficiency. The model is verified numerically by examining the conservation of mass flow of the lubricant. The dimensional analysis of the governing equation permits the model to be readily applied to any given film geometry. The computer model developed can evaluate the air film pressure distribution, load capacity, frictional force, and mass flow of an air bearing. The proposed computational scheme efficiently analyzes the performance of air-lubricated journal bearings at large eccentricity ratios. A similar procedure can be employed to investigate the performance of highspeed noncircular air bearing or gas-lubrication film under slip-flow conditions. This study gives an analytical basis for the design of orifice-compensated externally pressurized air-lubricated bearing. 相似文献
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《Tribology International》2003,36(8):169
Commercial base oil and oil fortifier added to this oil are used to investigate the frictional behavior of the engine journal bearings using the theoretical Reynolds equation and experimental test rig. In the theoretical part of the study, the Reynolds equation that states the pressure distribution and friction force with finite width was solved by using the finite difference method. In the experimental part of the study, a new design test rig was conducted to measure the friction force, the lubricant film thickness of the engine journal bearing using base oil under dynamical loaded conditions. The effect of oil fortifier was detected measuring the friction force every three minutes in each 360 crank angle during 15 minutes of experiment. As the theoretical friction results showed similar variation with the experimental measurements of engine bearings, adding oil fortifier to the base oil presented a substantial reduction of friction force during the testing period. 相似文献
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为降低发动机润滑油消耗以及由此带来的排放,活塞环缸套系统一般处于贫油润滑状态,特别是顶环与缸套间的贫油状况更严重。贫油状态下,活塞环-缸套间润滑油膜在出口区破裂后很难再形成,同时在燃烧上止点附近的高边界压力下气体承载也难以忽略。因此,以某柴油机顶环-缸套系统为分析对象,基于平均雷诺方程和无再形成边界条件,分析贫油和高边界压力下顶环-缸套界面间的润滑、接触和气体承载问题。研究结果表明,贫油工况下,由于油膜破裂后没有再形成,高边界压力的影响显著,对高爆压强化机型来说顶环-缸套间的气体承载力甚至会大于油膜承载力和接触承载力。 相似文献
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《Lubrication Science》2017,29(7):425-439
The proposed work concerns a theoretical and numerical investigation of the effect of solid particle contamination of lubricant oils on the static and dynamic characteristics of a finite length compliant journal bearing operating under isothermal conditions with laminar flow. In the present investigation, we use simple models based on the Einstein's mixture theory, which is characterized by the presence of suspended rigid particles in a fluid. Using the classical assumptions of lubrication, a Reynolds equation is derived and solved numerically by the finite difference method. The displacement field at the fluid film bearing liner interface due to pressure forces is determined using the elastic thin layer model. The results obtained show that the presence of suspended rigid particles in the lubricating oil (solid contamination) has significant effects on the hydrodynamic performance characteristics such as the pressure field, friction force, flow rate, elastic surface deformation as well as stability maps of the rotor‐bearing system (critical mass and whirl frequency) especially at high volumetric concentration. 相似文献
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A very recent analysis of the exact analytical solution of the Reynolds equation for the lubrication of the plain journal bearing with finite length is used in the current work in order to evaluate the impedance forces of the fluid film and define them in closed form analytical expressions. The main journal bearing design parameters such as the eccentricity ratio, the location of the minimum fluid film thickness, the location of the maximum pressure and the stiffness and damping coefficients are evaluated under the recent analytical definition of the lubricant pressure distribution and presented in charts as functions of the Sommerfeld number, comparing them with the past and recent literature. 相似文献
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采用有限差分法求解基于JFO(Jakobsson-Floberg-Olsson)边界条件(即质量守恒边界)下的雷诺方程,推导出连杆衬套油膜压力分布、油膜厚度、油膜承载力、润滑油端泄量表达式;建立连杆衬套在贫油润滑状态下的油膜压力分布模型,分析载荷对连杆衬套轴心轨迹位置、最大油膜压力和最小油膜厚度的影响。结果表明:在不同曲轴转速下,连杆衬套的润滑特性具有相同的变化规律,且在柴油机做功行程上止点的附近区域的油膜端泄量大于供油量,导致油膜的完整性被破会,形成空穴发生边界摩擦,甚至干摩擦或者磨损;连杆衬套与活塞销的最佳相对间隙为0.025%~0.05%。 相似文献
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This paper presents the analytical study of the effect of the bearing shell flexibility on the performance of multirecess hydrostatic journal bearing system operating with micropolar lubricant. The modified Reynolds equation for the flow of micropolar lubricant through constant flow valve‐compensated hydrostatic journal bearing has been solved by finite element technique based on Galerkins method, and the resulting elastic deformation in the bearing shell due to fluid‐film pressure has been determined iteratively, in which the deformation coefficient accounts for the bearing shell flexibility. The computed results suggest that the influence of the micropolar effect on bearing performance characteristics is significantly affected by the bearing shell flexibility. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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The high-temperature laser heating during heat-assisted magnetic recording (HAMR) causes the media lubricant to deform and transfer to the head via evaporation/condensation. The ability of the lubricant to withstand this writing process and sufficiently recover post-writing is critical for robust read/write performance. Moreover, the media-to-head lubricant transfer causes a continuous deposition of contaminants originating from the media at the head near field transducer, challenging the reliability of HAMR drives. Most previous studies on the effects of laser exposure on lubricant depletion have assumed the lubricant to be a viscous fluid and have modeled its behavior using traditional lubrication theory. However, Perfluoropolyether lubricants are viscoelastic fluids and are expected to exhibit a combination of viscous and elastic behavior at the timescale of HAMR. In this paper, we introduce a modification to the traditional Reynolds lubrication equation using the linear Maxwell constitutive equation and a slip boundary condition. We study the deformation and recovery of the lubricant due to laser heating under the influence of thermocapillary stress and disjoining pressure. Subsequently, we use this modified lubrication equation to develop a model that predicts the media-to-head lubricant transfer during HAMR. This model simultaneously determines the deformation and evaporation of the viscoelastic lubricant film on the disk, the diffusion of the vapor phase lubricant in the air bearing, and the evolution of the condensed lubricant film on the head. We investigate the effect of viscoelasticity, lubricant type (Zdol vs Ztetraol), molecular weight, slip, and disjoining pressure on the lubricant transfer process. 相似文献
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The present paper deals with the theoretical investigation of the influence of dimple geometry on fully textured hybrid thrust pad bearing and operating with non-Newtonian lubricant. The modified Reynolds equation which governs the flow of non-Newtonian lubricant in the clearance space has been solved using Finite Element Method. The simulated results indicate that the values of load carrying capacity, frictional power loss, maximum pressure and fluid film stiffness coefficient are significantly affected by the behavior of lubricant. The results presented in the study are expected to aid in determining the optimum value of dimple diameter and depth for the optimum bearing performance. 相似文献
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动静力混合润滑轴承三维温度场的研究 总被引:1,自引:0,他引:1
联立求解广义雷诺方程、三维能量方程、三维固体热传导方程及载荷平衡方程、油腔流量守恒方程和油腔能量守恒方程并考虑粘度随温度及压力、密度随粘度及压力的变化,在油膜与轴瓦界面使用热流连续性边界条件,得到动静力混合润滑轴承的三维温度场。结果表明动静力混合润滑轴承的温度分布比较均匀,在外载荷相同时,供油压力高时的最高温度略低于供油压力低时的情况。 相似文献