Influence of hydraulic losses on the friction of roller bearings

滚动转矩是描述滚动轴承效率的重要参数。这是内部摩擦的结果，内部摩擦影响轴承中的发热，也决定了其损失。轴承的总损耗可以分为不同的部分。主要部分是机械摩擦，其由滚动元件与跑道以及滚动元件与保持架之间的接触力引起。总摩擦力的第二部分是由润滑剂的位移和搅动引起的，称为水力损失。为了确定这些损失，轴承制造商提供了考虑润滑剂受各种因素影响的经验公式。其中一些影响因素是通过近似分配的。在DFG资助的一个项目中，申请人对垂直轴承布置进行了基础研究，以调查水力损失。因此，研究考虑到旋转对称的运行条件，考虑到轴承中的负载和润滑剂分布，并提供有关因素和发生的影响的重要见解。这些研究为调查油浴润滑和润滑剂不均匀分布的水平轴承布置的液压损失提供了条件，计划作为该后续项目的一部分。后续项目的目的是开发技术数学计算模型，该模型能够计算总摩擦扭矩，同时考虑到旋转不对称操作条件下的水力损失。这些计算模型的创建和验证，使用特定的组合实验测试以及MBS和CFD模拟考虑油浴润滑轴承的安排。对于专家来说，项目结果提供了分析或数值计算的机会，以考虑每个轴承部件表面的流体流动相关损失，这是最先进的方程所不可能的。

Frictional torque is a significant parameter to describe the efficiency of a roller bearing. It is a result of internal friction which influences the heat generation in the bearing and also determines its losses. The total losses of a bearing can be divided into different parts. The main part is mechanical friction which results from contact forces between rolling elements and the runway as well as rolling elements and the cage. The second part of total friction is caused by displacement of lubricant and churning, called hydraulic losses. To determine these losses bearing manufacturers provide empirical equations considering the influence of lubricant by various factors. Some of these influencing factors are assigned by approximation. In a project financed by DFG the applicants carried out basic research on vertical bearing arrangement to investigate hydraulic losses. Thus studies take into account rotationally symmetrical operating conditions with view to load and lubricant distribution in the bearing and provide important insights regarding the factors and the occurring effects. These studies provide conditions for the investigation of hydraulic losses of horizontally bearing arrangement with oil bath lubrication and non-uniform distribution of the lubricant, which are planned as part of this follow-up project. The aim of the follow-up project is the development of technical -mathematical calculation models which enable to calculate the total friction torque, taking into account hydraulic losses at rotationally asymmetrical operating conditions. These calculation models are created and validated by using a specific combination of experimental tests as well as MBS and CFD simulations considering oil bath lubricated bearing arrangements. For the expert the project results delivers the opportunity for analytical or numerical calculations to take the fluid flow related losses of every bearing part surface into account, which is not possible with the state of the art equations.