## 3 Theoretical Analysis of Friction Power Loss Distribution in HSLLRBs  
A single-row cylinder roller bearing is taken as an example. The geometry and material parameters of the roller bearing are given in Tables 1 and 2. The cage is made of H62 Cu material and the rest of the components use GCr15 bearing steel. The lubricant type is 4050(Sinopec inc., Beijing, China), which has a density of 971.2 kg/m\({}^{3}\). The inlet oil temperature is 50 \({}^{\circ}\)C. The effects of various operating parameters on the heat distribution of the bearing considering skidding are investigated.  
Figure 3: Flow chart of the bearing friction power loss analysis.  
Figure 4 shows the total friction power loss distribution and friction power loss distribution of various parts of HSLLRBs under different slip ratios. The results show that the friction power loss of the inner ring and outer ring as well as the total friction power loss of the bearing increase as the slip ratio increases, but that the friction power loss of the cage guide surface and roller oil churning show a reverse trend. The main reason for this is that the increase in slip ratio can reduce the cage speed and roller speed. In addition, the increase in inner ring speed and kinematic viscosity leads to an increase in the bearing friction power loss. As the slip ratio increases, the actual speed of the cage is reduced, the centrifugal force becomes smaller, the increase in the friction power loss of the outer ring raceway slows down, and the friction power loss generated by the outer ring raceway increases faster than that of the inner ring.  
Figure 5 shows the variation of the total friction power loss of the bearing under different slip ratios and inner ring speeds. The results show that, with the increase in inner ring speed, the total friction power loss increases; the higher the inner ring speed, the faster the increase in the total friction power loss. With the increase in the slip ratio, the total friction power loss of the bearing increases. The friction power loss of the bearing has a minimum when the inner ring speed is 25,000 r/min and the slip ratio is 0.2, because the reduction in the friction power loss of the oil stirring of roller and the guide surface of the cage are more than the increment in the friction power loss of the inner (outer) rings raceway under this working condition.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Value** & **Parameter** & **Value** \\ \hline Inner ring (mm) & 50 & Roller length (mm) & 12 \\ Outer ring (mm) & 90 & Roller number & 16 \\ Pitch diameter (mm) & 70 & Inner ring speed (r/min) & 18,000 \\ Roller diameter (mm) & 12 & Radial load (N) & 2000 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Geometry parameters of the roller bearing.  
Figure 4: Effect of the slip ratio on the friction power loss of the bearing.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Density (kg/m3)** & **Elastic Modulus (GPa)** &
\begin{tabular}{c} **Thermal Conductivity** \\ **(W/(m-k))** \\ \end{tabular} \\ \hline Cage & 8430 & 100 & 108.9 \\ Roller & 7830 & 208 & 46 \\ Rings & 7830 & 208 & 46 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Material parameters of the roller bearing.  
Figure 6 shows the variation of the total friction power loss of the bearing under different slip ratios and lubricant kinematic viscosities. The results show that, with the increase in the slip ratio, the total friction power loss of the bearing increases; with the increase in the kinematic viscosity, the total friction power loss of the bearing increases. Therefore, in the actual working condition of HSLLRBs, the kinematic viscosity of the lubricant at the same temperature is chosen to be as low as possible.