研究的可靠性,滑动轴承支撑斜盘式轴向柱塞泵型水液压外文翻译、毕业外文文献翻译、中英文翻译

Research on the reliability of sliding bearing support in a swash-plate type axial piston water hydraulic pump Yin F.L., Nie S.L. College of Mechanical Engineering and Applied ElectronicsTechnology Ruan J. Logistics department of the 92962th army Peoples Liberation Army of China Beijing University of Technology Beijing 100124, China Ruan J. Logistics department of the 92962th army Peoples Liberation Army of China Beijing University of Technology Beijing 100124, China Guangzhou 510700, China AbstractIn this paper, two kinds of different sliding bearing support structure including a traditional cross-shaft and a semi-shaft are designed for a water hydraulic pump.The characteristics of the two sliding bearings in each structure are calculated. By comparison, it is found that the working conditions of the two sliding bearings, especially the pv value, in the semi-shaft support structure are near to be identical in the cross-shaft one, which will be helpful to prolong their service life. Based on the Stress-strength interference theory, a reliability calculation model of the friction pair between the shaft and sliding bearings is proposed. The analysis results indicate that the semi-shaft sliding bearing support is beneficial to largely raise the inherent reliability of the water hydraulic pump as well as the service life of the pump. Keywordswater hydraulic pump； sliding bearing； pv value；Reliability .Introduction Water hydraulic system is operated with raw water(pure tap water) substituting for mineral oil. Such systems are becoming more and more popular, especially in the fields of steel and glass production, nuclear power generation, coal and gold mining, food and medicine processing, ocean exploration, and underwater robotics.Compared with conventional mineral oil, raw water that acts as hydraulic fluid has several inherent advantages,including low operating cost, sound environmental compatibility, non-flammability, and low pollution potential to products 1-2. Water hydraulic axial piston pump (WHAP) is one of key power components in water hydraulic systems. There are several challenging issues associated with the pump,such as conflicts between lubrication and wear, and between sealing and leakage. Especially, shaft and bearings form key friction pairs, which will result in significant influences on the pumps performance.Generally, the hydrodynamic sliding bearing is extensively used for supporting the water hydraulic pumps shaft. Therefore, in order to improve the pumps efficiency and reliability, it is crucial to study the force distribution of sliding bearings thoroughly. According to hydrodynamic lubrication theory, the critical points,which satisfies the wear resistance for sliding bearing and shaft of WHAP includes: (1) An optimal load distributed strategy should be used to determine optimal dimensions for achieving the even distributing of the load. (2) Several suitable materials should be selected to meet the water lubrication working conditions and to ensure a long life with lower friction losses 3. The concepts of both stress and strength relating to reliability design are generalized. In this paper, thereliability of sliding bearing support will be invest igated using Stress-strength interference model to calculate the reliability value of the sliding bearings, which will inc lude the effect of the flow fluctuation in WHAP. II. Description of sliding bearing support Figure (a) shows a schematic of a typical cross-shaft supporting structure. The cylinder block is supported on the shaft. Two sliding bearings are located on the cylinders left and right ends to support the shaft. Figure (b) shows a schematic of a novel design, where a semi-shaft supporting structure is employed. The front sliding bearing is used to support the input shaft (spline shaft). And the rear sliding bearing inside the cylinder is used to support the cylinder block. In the semi-shaft support structure, the spline shaft and cylinder are interference fit, and they are combined by a spline.During pump running, the motor drives input shaft rotating, bringing along the rotation of the cylinder.Because of the presence of the angle of swash plate, the whirling motion of the cylinder is translated into straight reciprocating motion of the pistons. When the cylinder rotated a period, the pistons reciprocate a round-trip to complete a process of suction and discharge of the pump. (a) cross-shaft support (b) semi-shaft support Fig. 1 Schematic diagram of sliding bearing support III. Theoretical analyses A. Load characteristics of the bearings.As shown in Figure 1, the reaction component force that act on a single slipper along X-axis and Z-axis can be respectively described as follows: In terms of the axial piston pump, the hydraulic pressure in each piston hole can be represented as: Then the radial resultant force is located in point O (as shown in Figure 1), and the radial resultant force can be expressed as: Furthermore, with the radial force equilibrium along the X-axis of the supporting structure, we have: The torque equilibrium along the X-axis can be written as: Through solving Eqs. (4) (6), the supporting force of the front and rear bearings can be obtained, respectively: B. PV value of the bearings For the valve plate distribution of axial piston pump,the number of pistons within the discharge pressure area (Zg) during one operating period is variably along with the reciprocating motion of the pistons. Ignoring the influence of the pressure pulsation in the pre-loading and pre-unloading areas, and the cylinder weight, affected by the alternative vibration of the number of piston in the discharge pressure area, the sliding bearing is subjected to periodic unstable loads. Water is characterized by very low dynamical viscosity, which is regarded as poor lubricating properties affecting the performance of sliding and rolling contacts 4. Here it appears that it is impossible to obtain an acceptable film thickness in water lubricated sliding bearings. Consequently, in practical work, the sliding bearings in WHAP are usually working under the condition of an incomplete liquid lubrication. Especially, at the points of turn on / off, the direct contacts between the matching pairs of the shaft and sliding bearings may take place. Moreover, since it is necessary for the sliding bearings the surface hardness should be as high as possible in order to sustain contacting pressure, and thus, the abrasion between the shaft and bearings would be as low as possible in order to improve the sliding bearings reliability. It is essential to select several suitable materials and matching pair. The siding bearings in this paper are made of WR525, which is a thermoplastic composite consisting of carbon fiber in a PEEK matrix. Due to its unique thermal expansion properties, WR525 is ideal for use as impeller wear rings, bushings and case wear rings.WR525 allows the pump user to increase pump efficiency by running tighter wear ring clearances, while decreasing potential pump damage when pumps are cavitated or experience down-line bearing failures. WR525 bearings are specified as standard material on all HGM/HGM-RO boiler feed pumps. As it is known, the critical pv value is a very important parameter for polymers or their composites in tribological applications, and has been widely used in investigation of ploymers sliding wear behaviors. Besides, pv limits are affected by variations in temperature, speed,loading,lubrication and surface finish. Exceeding pv limits will result in accelerated wear and premature bearing failure, where p is the intensity of pressure applied to a bearing surface and v is the relative velocity 5. Furthermore, the pv value is proportional to bearings wear, friction power loss and friction heat 6. Wear, friction power loss and temperature conditions are the three key index of the service life of the bearings. Therefore, the pv value can be used to preliminarily evaluate the sliding bearingsworking life in a WHAP. Generally speaking, in order to guarantee the boundary lubricated bearing running reliably, it is necessary to meet the following three conditions 7: Bearings average working specific pressure is: Substituting Eqs. (7) and (8) into Eq. (10), average working specific pressure of the front bearing can be obtained as: And average working specific pressure of the rear bearing can be represented as: Radial circumferential velocity of the shaft is: The friction specific work rate of sliding bearing can be expressed as Substituting Eqs. (11) (13) into Eq. (14), the friction specific work rate of the front bearing can be obtained as follows: And the friction specific work rate of the rear bearing is calculated as follows: Based on the structure parameters of the WHAP, taking the peak number of pistons in the discharge pressure area (Zg), the working conditions of the bearings under the two different structures are calculated in Table1. C. Scale factor Actually, analyzing Eqs. (10), (11), (14) and (15), it is found that the dz, B and influence the match of the two bearings working conditions. Define the bearingslinear velocity ratio asa verage specific work rate ratio as Then we have: The three parameters mentioned above can be calculated (as shown in Table 2). D. Reliability model and evaluation In terms of a WHAP, design of the sliding bearing is an important part for raising its reliability. In this paper, the pv value is defined as the stress between the sliding bearing friction pair-Y, and it is a random variable. The allowable pv value pv can be defined as the strength-X. Generally speaking, the contact stress p between the friction pair and the relative linear velocity v are mutually independent random variables, and they are all distributed normally, so the product pv is also distributed normally.Thus, according to the formula when the stress and strength are all distributed normally, the reliability coefficient can be determined by means of the equation: In fact, the pv or allowable pv value can be expressed by the two random variables Pd and ： K is constant coefficient. Pd is the working pressure of the pump and is the relative angular velocity. Based on probability theory, the average value and the standard deviation can be obtained, respectively: Through solving Eqs. (22) and (23), we have: The rated pressure of the WHAP can be allowed for fluctuating within 5%. According to the definition of mean value and the principle of3 , we have: The allowable pv value pv of WR 525 is 8.89MPa m/s, and its standard deviation pv s is 0.315.Substituting Eqs. (24) (28) and their corresponding data into Eq. (20), the reliability coefficient R u of the two kinds of structure can be calculated respectively. Hence, the corresponding reliability R for each structure can be obtained, as listed in Table 3. IV. Discussion In terms of the WHAP, the failure of any sliding bearing could destroy the pumps supporting and balance to cause severe noise and vibration. It also could lead to the invalidation of the flow distribution and make the volumetric efficiency decrease sharply. Thus, service life of WHAP is determined by the bearing which has the severe working condition. Table 1 presents the calculated results of the key parameters in two different sliding bearings distribution structure. It indicates that the working conditions of the sliding bearings in each distribution structure are different.Firstly, the center distance L2 in the semi-shaft structure is smaller than the cross-shaft one. This means that the rear bearing in the semi-shaft structure is closer to the center point of the resultant force, and the distance between the front and bearing is also smaller. Thus it is favorable to balance the torque of F1 and F2 so that making the sliding bearings work smoothly. Secondly, the loads on the sliding bearings in each structure are different. In the cross-shaft structure, the loads on the front bearing are much larger than on the rear one. However, in the semi-shaft structure, the loads on the front bearing reduced, while the loads on the rear bearing increased, so as to make the bearings supported load condition in the front and rear location closely and their loads distributed evenly. Additionally, the front bearings average working specific pressure (pz) and its pv value in the cross-shaft structure, are much larger than the rear one. However, in the semi-shaft structure, the front bearings pz and pv value reduced slightly, for which the rear bearing increases a little. Comparing the results listed in Table 2, it can be seen that the value of the semi-shaft structure are smaller than which are in the cross-shaft structure. Moreover, these values are close to 1. It is revealed that in the semi-shaft structure, the working conditions of the two sliding bearings are near to be identical. From Table 3, the reliability value of the siding bearings support in the semi-shaft structure are higher. It is indicated that the sliding bearings of the semi-shaft have longer service life than those in the cross-shaft.Consequently, it can be concluded that the distribution of sliding bearings in the semi-shaft structure is beneficial to make the bearings working conditions equilibrium and to improve the reliability of the pump. V. Conclusion In this research, two sliding bearings of the WHAP which have the same size work in the same water medium in same time. So the change law of loads on the bearings similar. Besides, they are made of the same material: WR525. Hence, the life of the two sliding bearing support structure depends on the bearing which has higher working conditions especially the pv value. So it is important to design a rational structure arrangement to make the two bearings working conditions as equal as possible. Consequently, for the sake of raising the sliding bearings life in the WHAP, the scale factors must be close to 1. Additionally, the degree of reliability is a main indicator for the reliability of the sliding bearing support structure. So the reliability value of the sliding bearing support structure should be as large as possible for improving the WHAPs reliability. By comparing the working conditions of the sliding bearings in each structure, it is found that the pv value of the two sliding bearings in the semi-shaft structure are closer than in the cross-shaft one. And the scale factor of the semi-shaft structure are closer to 1, compared to the cross-shaft one. Additionally, the reliability value of the sliding bearings in the semi-shaft structure is higher than which in the cross-shaft one.Obviously, all the comparisons mentioned above show that the arrangement of sliding bearings in the semi-shaft structure does a better job in achieve the purpose of distributing the load averagely and raising the service life of the sliding bearings in the water hydraulic piston pump as well as improving the reliability of WHAP. ACKNOWLEDGMENT This research was funded by Natural Science Foundations of China (s 50675074 and 51075007), NCET of State Education Ministry ( NCET-07-0330), and PHR (IHLB) 20090203. REFERENCES Nomenclature The author；Yin F.L. Nie S.L. Ruan J. Nationality:China Source:The 2011 International Conference on Fluid Power and Mechatronics, Beijing, August 16-17, 2011, 282-286. 研究的可靠性 ,滑动轴承支撑斜盘式轴向柱塞泵型水液压 Yin F.L., Nie S.L. 大学的机械工程和应用 ElectronicsTechnology Ruan J. 中国 北京 北京科技大学 中国人民解放军 物流部门的 92962部队 100124 Y 中国 广州 510700 文摘 -在本文中 ,两种不同的滑动轴承支撑结构包括一个传统的十字轴和半轴 ,被设计为 -水液压泵 。 滑动轴承在每个结构计算。相比之下 ,特别 是两个根据应力 -强度干涉理论 ,一个可靠性计算模型之间的摩擦副轴和提出了滑动轴承。分析结果表明 ,半轴滑动轴承的支持是有益的 ,很大程度上提高固有可靠性的水液压泵以及泵的使用寿命。 滑动轴承 pv 值 ,在半轴支撑结构都是相同的附近的十字轴 ,这将有助于延长其使用寿命。 关键词 水液压泵 ；滑动轴承 ；pv 值 ；可靠性 介绍 水液压系统的原始水 (纯自来水 )取代了矿物油。 这种系统正变得越来越流行 ,尤其是在田野的钢铁和玻璃生产、核电、煤炭、黄金矿业、食品和医药处理、海洋探险 ,水下机器人 。 与传统的矿物油 ,原水 ,充当液压流体有几个固 有优势 ,包括更低的运营成本、合理的环境兼容性、耐燃性、低污染潜力产品 1-2。 水液压轴向柱塞泵 (重击 )是一个关键的动力组件在水液压系统。 有几个挑战性问题相关的泵 ,如冲突之间 ,润滑和穿密封和泄漏。特别是 ,轴和轴承形式主要摩擦副 ,这将导致显著影响泵性能。通常 ,水动力滑动轴承是广泛用于支持水液压泵的轴。因此 ,为了提高泵的效率和可靠性 ,这是至关重要的 ,研究了滑动轴承力分布的彻底。根据流体动力润滑理论 ,关键的点 ,这满足了耐磨性的滑动轴承和轴的重击包括 :(1)一个最佳负载分布策略应该用于确定最优尺寸对实现甚至分发的 负载。 (2)几个应该选择合适的材料 ,以满足水润滑的工作条件 ,确保一个长寿命和低摩擦损失 3。 二者的概念的应力和强度可靠性设计有关的推广。在本文中 ,可信度的滑动轴承的支持将被采用了应力 -强度干涉模型来计算可靠性价值的滑动轴承 ,这将包括流动的影响波动。 描述的滑动轴承的支持 图 (a)展示了一个示意性的一个典型的十字轴支承结构。缸体的轴上的支持。两个滑动轴承位于汽缸的左和右端支持轴。图 (b)显示了一个新颖的设计原理 ,在那里一个半轴支承结构采用。前面的滑动轴承是用来支持输入轴 (花键轴 )。和后方滑动轴承在气缸内 用于支持缸体。在半轴支撑结构、花键轴和圆柱干涉配合 ,他们结合的花键。在泵运行时 ,马达驱动器输入轴旋转 ,带上的旋转圆筒。因为存在的防波板的角度 ,旋转运动的缸是翻译成直线往复运动的活塞。当缸旋转一个时期 ,活塞往复运动的往返来完成一个过程的入口及出口的泵。 （ a） 十字轴的支持 （ b）半轴的支持 图 1示意图的滑动轴承的支持 理论分析 a 的负荷特性轴承。如图 1所示 ,反应分力 ,作用于一个滑块沿着 x 轴和 z 轴可以分别描述如下 : 在术语的轴向柱塞泵、 液压在每个活塞孔可以表示为 : 然后径向合力位于点 O(如图 1),和径向合力可以表述为 : 此外 ,由于径向力平衡沿着 x 轴的支承结构 ,我们有 : 沿着 x 轴的扭矩平衡可以写成 : 通过求解方程式。 (4)-(6),支持力量的前后轴承可以分别获得 : B PV 值的轴承 对于阀板分布的轴向柱塞泵 ,活塞的 数量在放电压力区 (Zg)在一个操作周期是不定地随着活塞的往复运动。忽略压力脉动的影响在预加载和 pre 卸货区 ,汽缸重量 ,受替代振动的数量活塞在放电压力区 ,滑动轴承受到周期性不稳定的负载。水具有非常低的动力粘度 ,它被认为是贫穷的润滑性能影响性能的滑动和滚动接触 4。这里似乎是不可能获得一个可接受的膜厚度在水润滑滑动轴承。因此 ,在实际工作 ,滑动轴承在打败通常工作条件下的一个不完整的液体润滑。特别是 ,在点开 /关 ,直接接触摩擦副之间的滑动轴承的轴和可能发生。此外 ,因为它是必要的滑动轴承表面硬度应该尽可能高的为了维持 接触压力 ,因此 ,磨损的轴和轴承之间会尽可能低为了提高滑动轴承的可靠性。 它是必要的选择几个合适的材料和匹配的一对。外墙轴承在本文是由 WR525,这是一种热塑性复合构成的碳纤维在 PEEK 矩阵。由于其独特的热膨胀性能 ,非常适合用作 WR525叶轮磨损环、衬套和案例穿环。 WR525允许泵用户增加泵效率进行更严格的穿环间隙 ,同时减少潜在的泵损坏当泵 cavitated 或经验的下线轴承故障。 WR525轴承被指定为标准物质在所有 HGM / HGM-RO 锅炉给水泵。 众所周知 ,关键的 pv 值是一个非常重要的参数对聚合物或他们的 复合材料在摩擦学的应用程序 ,并已广泛应用于调查 ploymers“滑动磨损行为。此外 ,pv极限温度变化的影响、速度、加载 ,润滑和表面光洁度。超过光伏限制将导致加速磨损和过早轴承故障 ,p 是压力强度应用于轴承表面 ,v 是相对速度 5。此外 ,pv 值成正比轴承的磨损、摩擦功率损耗和摩擦热 6。穿 ,摩擦功率损耗和温度条件下的三个关键指标的轴承的使用寿命。因此 ,pv 值可用于初步评估滑动轴承的工作生活在一个重击。一般来说 ,为了保证边界润滑轴承运行可靠 ,必须满足以下三个条件 7: 轴承的平均工作特定压力是 : 取代 方程式。 (7)和 (8)到 Eq。 (10),平均单位压力的工作前轴承可以得到 : 和平均单位压力的工作后轴承可以表示为 : 径向圆周速度的轴是 : 具体工作率的摩擦滑动轴承可以表达为 取代方程式。 (11)-(13)到 Eq。 (14),摩擦具体工作率的前轴承可以得到如下 : 和摩擦率的具体工作后轴承是计算方式如下 : 基于结构参数的重击 ,采取的峰值活塞在放电压力区 (Zg),工作条件下的轴承的两个不同的结构计算中。 C 比例因子 实际上 ,分析方程式。 (10),(11),(14)和 (15),它是发现 dz,B 和 比赛的两个轴承工作条件。定义轴承 linear 速度比 特定工作率比 我们有 : 上面提到的三个参数可以计算 (如表 2所示 )。 D 可靠性模型和评价 从一个重击 ,滑动轴承的设计是一个重要的部分为提高其可靠性。摘要 pv值定义为应力之间的滑动轴承摩擦副 y,它是一个随机变量。允许的 pv 值 (pv)可以被定义为强度 x。一般来说 ,接触应力 p 之间的摩擦副和相对线速度 v 是相互独立的随机变量 ,并且他们都是正态分布 ,所以产品 pv 也正态分布。因此 ,根据公式当