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1.
烧瓦是农用车常见的故障之一。烧瓦就是发动机曲轴轴承与连杆轴承的瓦片摩擦表面温度过高,使瓦片合金熔化脱落。烧瓦多属于人为的事故。一、烧瓦的原因主要是由于润滑油供应不足,瓦片没有形成良好的润滑油膜,使曲轴与瓦片的润滑不良或形成干摩擦。造成润滑不良的常见原因是:1.油底壳润滑油不足。主要是由于发动机润滑油突然渗漏,而造成油底壳润滑不足。例 相似文献
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CVT刚性联接发动机曲轴轴系结构的扭振分析 总被引：1，自引：0，他引：1
因非道路车辆的特殊结构和成本限制,提出四缸柴油发动机中采用CVT刚性联接曲轴轴系结构。阐述了该新型结构的特征和工作原理,建立了四缸柴油发动机离合式曲轴计算模型和CVT刚性联接曲轴计算模型。通过曲轴前端实验,证明了所建模型和模型参数确定方法的正确性。求解所有计算模型,并对结果进行对比分析。结果表明,CVT刚性联接使曲轴轴系振动波动加大,减振器耗散能增加,各阶共振峰值对应转速低减。对曲轴各拐剪切应力幅度的影响不大,但有高转速工况降低而中低转速剪切应力幅值增加的普遍趋势,CVT端的扭振振幅和剪切应力较大些。综合研究得出结论：非道路车辆低速四缸柴油发动机可以采纳CVT刚性联接曲轴轴系结构。 相似文献
3.
为了研究水润滑橡胶合金轴承结构参数对其低速重载工况下摩擦噪声的影响,使用复模态分析方法建立了水润滑橡胶合金轴承系统仿真模型,采用专业仿真软件分析了不同摩擦系数及结构参数条件下摩擦噪声产生的概率,进而研究结构参数对摩擦噪声的影响,进行了平板型和圆弧型结构的水润滑橡胶合金轴承摩擦噪声的对比实验。研究结果表明,水润滑橡胶合金轴承的水槽半径大小、摩擦面形状以及摩擦副的摩擦系数对水润滑橡胶合金轴承的摩擦噪声有较大影响,而水槽的形状对轴承摩擦噪声的影响不大。对一定结构尺寸的水润滑橡胶合金轴承,水槽半径为4 mm、平面型摩擦面的结构可以大大减少轴承出现摩擦噪声的可能性,相关实验结果与计算结果是吻合的。 相似文献
4.
根据舰船推进装置对水润滑轴承系统的运行精度要求,通过建立水润滑橡胶轴承系统有限元接触模型,研究不同橡胶硬度、厚度对直槽和螺旋槽水润滑橡胶轴承系统跳动量的影响规律,提出水润滑轴承系统跳动量控制方法。研究结果表明,水润滑橡胶轴承系统跳动量随橡胶硬度增大而减小,随橡胶厚度增大而增大。当橡胶硬度在85~95 Shore A时,轴承系统主轴跳动量较小。在保证沟槽尺寸的前提下,尽量设计成较薄的橡胶厚度。相比直槽结构,螺旋槽水润滑橡胶轴承系统跳动量更小。因此,科学合理地设计水润滑橡胶轴承橡胶衬层材料硬度和几何结构,能显著减小轴承系统的跳动量,提高运行精度。 相似文献
5.
弹性波作用下渗流多孔介质微粒运移分析是对目前静态流体或稳态多相渗流中微粒运移/捕集的补充,通过分析弹性波对微粒剥离运移捕集过程的影响,建立弹性波作用下微粒运移模型,得到对微粒运移效果和储层物性变化的影响规律。由推导得到的弹性波作用下微粒剥离临界速度可知,当微粒与孔喉半径的比值越小时弹性波导致的振荡附加力影响越大,临界速度与流体粘度、微粒/孔喉半径比成负相关,与基质胶结程度、结构力、微粒半径、微粒密度成正相关。弹性波作用下微粒运移模型需同时考虑多孔介质渗流速度的变化,此时微粒剥离释放速率增加,但随着波衰减和时间延长而降低,微粒在孔隙表面沉积滞留速率先上升后下降,喉道堵塞的速率有所上升,说明弹性波作用下微粒的剥离和悬浮能力增加,但亦增加了微粒在微细孔喉"架桥"堵塞的可能性。研究结论对岩石物理学和工业化波动处理涉及的储层物性研究具有一定指导意义。 相似文献
6.
一、205型轴承钢球架烧散原因产品出厂时,205型轴承座内加入的黄油量不足,主离合器轴在205型轴承内长时间干摩擦造成的。由于主离合器是在2个94908型滚针和1个205型轴承的支撑下工作,故当205型轴承的 相似文献
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8.
大型渠道水荷载加载过程中渠床变形特性 总被引：1，自引：1，他引：0
为了研究改建后的大型渠道在首次加荷过程中产生的沉降位移量是否会对灌溉设计产生较大影响,笔者基于大型梯形渠道弧形底混凝土防渗渠加荷与卸荷过程中变形观测原位试验,分析了改建后的大型渠道在首次加荷与卸荷过程中渠床的变形特性。结果表明：改建后的大型渠道在首次加荷与卸荷过程中,会发生一个较大的弹性变形及塑性变形,渠道在垂向上的沉降量与回弹量的大小随外荷载不断变化具有一定特征;改建后的大型渠道在首次加荷过程中产生的沉降位移量与渠底以下非饱和土壤的厚度有较大关系;由于渠道在首次加荷与卸荷过程中在垂向上有较大的沉降量,则为满足灌溉条件,应在渠道的设计与施工中采取一定的必要措施。 相似文献
9.
一、轮胎变形拖拉机停驶以后,自身重量完全由4个轮胎承受,使得轮胎接触地面的部位承受压力过大而变形。拖拉机停驶时间越长,轮胎变形部位越不易恢复,即由弹性形变成了塑性形,就会使拖拉机在行驶时车身震动加剧,同时也加速轮胎的磨损,缩短轮胎的使用寿命。应对措施:拖拉机长时间停放时,可将拖拉机支起来,或者每隔几天将拖拉机前后移动1次,避免拖拉机重量长期压在轮胎的同一个位置上。另外,拆下的轮胎在保管时要避免挤压。二、润滑不足拖拉机长期存放,会造成润滑不足。原因是由于发 相似文献
10.
为深入了解饱和黏弹性半空间地基中摩擦桩的竖向振动特性,基于Boer多孔介质理论,考虑激振频率对摩擦桩桩底土体动刚度的影响,采用平面应变模型并结合桩土接触面的混合边值条件,推导求解得出了饱和黏弹性半空间地基中摩擦桩的竖向动力阻抗模型公式和桩顶速度时域响应解并验证了其合理性。进一步通过参数化对比分析探讨了桩基埋深比和土体渗透系数对所得竖向动力阻抗和桩顶速度时域响应的影响规律。解析推导得出的对应竖向动力阻抗模型公式和桩顶速度时域响应解,丰富了桩基动力学的理论,可为相关工程实践提供参考和理论支持。 相似文献
11.
Three-dimensional finite element analysis for thermo-elasto-hydrodynamic performances for a water lubricated bearing system 总被引：1，自引：1，他引：0 
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下载免费PDF全文 MENG Fanming 《保鲜与加工》2013,(2):121-126
Three-dimensional liquid-solid coupling finite element analysis for thermo-elasto-hydrodynamic performances for a water-lubricated bearing system is conducted using finite element code, based on the influence coefficient method, and nonlinear optimization method. Meanwhile, the code is validated. Numerical results show that significant elastic deformation and thermal deformation, contact pressure with certain amplitude, and large temperature rise over the range of the small film thickness-roughness ratio can occur for the bearing. Therefore, the above deformation and temperature rise should be considered in designs and applications of water-lubricated bearings. 相似文献
12.
It''s difficult to form hydrodynamic lubrication because of the low viscosity of water, but it is founded by experiment that there is low co-friction on water lubricated plastic alloy bearings working. The main factors that affect co friction are revs, loaded and clearance. Significance and effect of every factor that affect co friction is analyzed by variance analysis and orthogonal experiment. goaphs of every factor that affect co friction are list. From the goaphs, it is founded that there is elastic hydrodynamic because of elastic deformation in the plastic alloy. 相似文献
13.
According to the characteristic of contact and lubrication of double enveloping hourglass worm gearing,a simplified contact model that can simulate the lubrication mechanism of coupling effect of squeezing effect and entraining effect of this worm gearing is presented.A simulating test set is designed.The lubrication mechanism of coupling effect of squeezing effect and entraining effect is studied experimently by using this set.And the influences of rotation speed,loading speed and depth of oil pocket on the forming of lubrication film and loading ability between contact surfaces are analyzed.Some beneficial conclusions are obtained. 相似文献
14.
This paper develops a generalized 3-dimensional 14-DOF dynamic model for hypoid gear which considers the time-varying friction coefficient and lubrication situation. We propose a mixed elastohydrodynamic lubrication(EHL) friction model of hypoid gear tooth contact to reflect the realistic lubricant situation in gear transmission system consisted of full film contact and asperity contact. Under the mixed lubrication condition, the effects of time-varying friction coefficient on gear dynamic is analyzed. The load sharing coefficient is used to calculate the instantaneous friction coefficient at each contact point along the contact path. Friction coefficient model based on mixed elastohydrodynamic lubrication(Mixed EHL) is incorporated into the dynamic model to predict the dynamic mesh force and transmission error with constant and time-varying friction coefficient. The simulation results under a wide range of speed and load show that the time-varying friction coefficient has a marginal effect on the dynamic response. 相似文献
15.
An original thermodynamic idea for Power MEMS, which is called as quasi gas power cycle, is proposed to further intensify energy density and simplify structure of Power MEMS. Because gas supply with preset high pressure is set up in the Power MEMS engine of quasi gas power cycle, it is convenient for the Power MEMS engine to employ externally pressurized gas bearings to improve the performance of its bearings. Therefore mal design philosophy and structural type of the hyrostatic journal bearing as well as the hyrostatic thrust bearing in the Power MEMS engine are investigated, considering the limiting factor on meso scale. Then the structural and operational parameters are analyzed, and the optimal designs of typical externally pressurized gas bearings are put forward. Moreover the feasibility of the externally pressurized gas bearings applied to the Power MEMS engine is further verified by the calculation of load-carrying capacity of the hyrostatic gas bearings. 相似文献
16.
Based on study of elastohydrodynamic lubrication (EHD) and meshing theory of planar worm gear drive, EHD model for the drive is proposed. Minimum film thickness on the whole contact area is calculated. EHD status for the drive is analyzed. The distributions of film thickness show that, EHD status during entry engagement is better than that during exit engagement, and EHD status of worm addendum area is better than that of dedendum area. Influencing factors such as work conditions and optimized parameters along with their effects were analyzed. Theoretical analysis suggests that the optimizing pressure angle and increasing worm pitch diameter have influence on improving lubricant performance of the planar worm gear drive. 相似文献
17.
Structural parameters, such as the structure of recesses, the number of recesses, and throttle parameters, play decisive roles in determining the carrying capacity and rigidity of oil film bearings. These parameters are analyzed, and a state design is presented for a hydrostatic cavity and pat bearing, a hybrid bearing with an eccentric oil wedge, and ladder recesses. The mutual relationships between oil film bearing structural parameters and carrying capacity are calculated by combining numerical methods using MATLAB software programming. The results show that hybrid bearings with ladder recesses have superior carrying capacity compared to bearings with other structural forms. 相似文献
18.
Experimental study on acoustic emission characteristics of coal rock at different confining pressure 总被引：1，自引：0，他引：1
This paper conducts experimental investigation on acoustic emission(AE) characteristics of coal rock at uniaxial and triaxial compression by MTS815 rock mechanics test system. The results show that the variation of AE has tendency effect at uniaxial compression and confining pressure experiments. We indicate that AE signal decreases significantly in the elastic stage, and the relatively quiet period of AE before the specimens failure is not obvious under confining pressure. The AE amplitude distribution with time and its envelope line can indirectly reflect the trend of stress. The AE events peak stress and elastic modulus decrease with the temperature increase, and the value of m which reflects the cumulative distribution of amplitude increases as the confining pressure rises. The results also show that the AE frequency distributes in three frequency domains, and the proportions of dominant frequency significantly increase while the specimens are broken. 相似文献
19.
With the linearization of the flow in oil chambers, the continuity equation of flow and the dynamic equation of the shaft are built for the hydrostatic journal bearing and thrust bearing respectively. Next, the transfer functions of the two bearings with capillary throttle are deduced. Then, the performance of the two bearings is simulated in Matlab. In general, the simulation results are well matched to the experimental data provided by Guangzhou Machine Tool Research Institute. It indicates that both of the models can predict the dynamic characteristic of the two bearings. Finally, the dynamics response of the hydrostatic thrust bearing is studied in various rotational speed of the shaft. Also, the dynamic performances of journal bearing are simulated in changing of inlet pressure and thickness of oil film. 相似文献
20.
The investigations on the deformation mechanisms, estimation of stability and technique of disasters controlled of brittle rocks excavated under high geostress are difficult points for rock mechanics and engineering geology. The evolutionary rule of mechanical parameters and deformation failure of brittle rocks are discussed based on unloading under high geostress, and the obvious characteristics of strain strength for brittle rocks under high geostress is found. It is presented that the brittle rock yielded follows Griffith rule of strain strength at peak. The elasto brittle plastic numerical calculation method is established considering the dynamical variation of mechanical parameters in course of unloading yield, and it is validated by practical engineering. 相似文献