Tribological Characteristics of Electric Sliding Contacts With Oil-Impregnated Porous Materials

电动滑动触点广泛应用于汽车等电气元件中。本研究的目的是通过将传统烧结金属轴承中使用的多孔材料应用于滑动触点的表面材料，改善滑动触点的性能特征，延长滑动触点的使用寿命。本文从理论和实验两方面研究了多孔材料的渗透率对其电导率和摩擦特性的影响。本研究中使用的滑动触点包括一个具有凸表面的无孔滑块（定子）和一个旋转的多孔盘（滑块）。实验分析采用销盘摩擦试验机，测量滑动触点之间的摩擦力和接触电压。通过数值分析，得到了滑座与旋转盘接触区域的油膜压力分布、油膜力和摩擦力。这些特性通过同时求解包含滤波项和切向速度滑移影响的修正雷诺方程和由达西定律导出的拉普拉斯方程来计算。结果表明，数值计算结果与实验结果定性吻合。多孔材料渗透性的增加使连续金属接触下的工作条件延长到η u_0l /w_f （η：油粘度，U_0：滑动速度，B：滑座宽度，w_f：施加载荷）定义的无因次轴承特征数S的较高值，并且减小了滑座与圆盘表面电接触处的最大摩擦力。这表明多孔材料比传统的非多孔滑动触点产生更低的摩擦损失和更长的使用寿命。因此，作为滑动接触材料，油浸多孔材料比传统的无孔材料具有更大的优势，因为它可以在大范围内以较低的摩擦力在滑块和滑块的连续金属接触条件下工作

The electric sliding contacts are widely used in electrical components such as for automobiles. The purpose of the present study is to improve the performance characteristics of the electric sliding contacts and to extend their lifetime by applying the porous materials used in conventional sintered metal bearings to the surface materials of the sliding contacts.The effects of the permeability of porous materials on the electrical conductivity and the frictional characteristics have been investigated theoretically and experimentally. The sliding contacts used in the present study consist of a nonporous rider (stator) having convex surface and a rotating porous disk (slider). The experimental analysis is conducted with a pin-on-disk friction tester to measure the frictional force and the contact voltage between the sliding contacts. The numerical analysis yields the oil-film pressure distributions, the oil-film force and the frictional force at the contact area between the rider and the … More rotating disk. These characteristics are calculated by simultaneously solving the modified Reynolds equation, which includes the filter term and the effect of tangential velocity slip, and the Laplace equation derived from Darcy's law.The results show that the numerical and the experimental results agree qualitatively. An increase in the permeability of the porous materials extends the operating conditions under the continuous metal contact to a higher value of the dimensionless bearing characteristic number S defined by ηU_0L/w_f (η : oil viscosity, U_0 : sliding speed, B : width of rider, w_f : applied load), and also decreases the frictional force at the maximum value of S where the rider could make electrical contacts with the disk surface. This suggests that the porous materials yield a lower frictional loss and a longer lifetime than the conventional nonporous sliding contacts.Consequently, the oil-impregnated porous materials have superiority over the conventional nonporous ones as sliding contact materials from the viewpoint that the rider and the disk could operate under continuous metal contact condition with a lower frictional force for a wide range of S. Less