Tham khảo tài liệu 'tribology - lubricants and lubrication part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 112 Tribology - Lubricants and Lubrication These models should be used in accordance with the terms of the friction pairs. In this case the use of non-Newtonian models of lubricants does not exclude taking into account the dependence of oil viscosity on temperature and pressure in the lubricating film of friction pairs Prokopiev V. et al. 2010 a T C1 exp C2 T C3 34 where C1 C2 C3 - constants which are the empirical characteristics of the lubricant. The coefficients Cị are calculated using the formula following from the dependence 34 C3 T1 T3 - T2 lnI Al - T3 T2 - T1 lnI A IA2 I A3. T3 - T2 lniAi- T2 - T1 lníAi 35 ln A C _La C2 ----- --------- C -----A1 . . T -T1 1 exp C2T1 To account for the dependence of viscosity on the hydrodynamic pressure the Barus formula is acceptable . a-p Ap A0e p 36 where Ao - viscosity of the lubricant at atmospheric pressure p - hydrodynamic pressure in the lubricating film a - piezoelectric coefficient of viscosity which depends on temperature and chemical composition of lubricants. On the base of a combination of models 28 34 and 36 the authors propose to use a combined dependence of viscosity versus shear rate pressure and temperature A k Y -1 ea T p C1 CJ- C3 . 37 The effect of hydrodynamic pressure in the film of lubricant on the HMCh of the connecting rod bearing is reflected in the Table 4 and Fig. 11. Hydromechanical N T _ QB hmin sup Pmax inf hmin characteristics W C l s Am MPa Am numerical value 610 5 1 105 9 0 02345 4 416 280 3 1 930 670 4 2 106 9 0 02420 5 712 588 6 2 560 1 - oil viscosity is independent of pressure 2 - viscosity depends on pressure. Table 4. The results of the calculation of hydro-mechanical characteristics of the connecting rod bearing for the dependence of viscosity on pressure As seen from Table 4 and Figure 11 in the case of taking into account the effect of hydrodynamic pressure on the viscosity of the lubricant all the values of HMCh of the bearing increase. In particular the mean-power losses .
