To understand the effect of the number of torque converter blades on the performance of torque converters, in this paper, we employed computational fluid dynamics and the response surface method to optimize the design of the torque converter. The number of pump blades, stator blades and turbine blades were used as design variables, and the torque transmission ratio and pump capacity factor were used as objective functions for multi-factor optimization design. The results show that the number of turbine blades had no significant impact on the converter’s performance, while the number of pump blades and stator blades had significant impact and showed strong correlation. Compared with the original torque converter, the optimized converter increased the starting torque ratio by 0.12 and the efficiency by 4%. It shows that the computational fluid dynamics and the response surface method can be combined to determine the optimal number of blades in the design of torque converters to reduce the cost and experiment time.

The formation of hydrodynamic lubrication is analyzed based on an experimental study of the hydrodynamic lubrication characteristics between two parallel surfaces with different types of surface texturing. The study considers planar samples of C45 steel and accounts for the thermal expansion of 304 stainless steel in the experimental apparatus at oil temperatures of 323.15 K and 353.15 K. The experiments involve the use of a rotating rheometer at various angular speeds, with the effect of thermal expansion that occurs in actual applications being simulated by varying the gap between the planar sample surfaces. The experimental results show that (i) the lubrication properties of the planar textured samples depend strongly on temperature and (ii) the load-carrying capacity of the textured samples is considerably greater than that of the non-textured samples.

The hypoid gear pair is a main part of driving axle and it is one of the main sources of vibration and noise in the automobile transmission. Study on mechanisms of vibration and noise of the hypoid gear pair, and investigating on reducing its vibration and noise are of great significance. Firstly, a simplified dynamic model of the hypoid gears of main reducer, with considering the time-varying teeth stiffness and teeth surface friction damping, was established. Then, on the basis of the above work, a non-linear vibration equation of the hypoid gear with the backlash was derived. Lastly, a numerical simulation method was employed to calculate different gear backlash effects on the hypoid gear vibration behaviors caused by the gear worn, and effects on the gear non-linear vibration from different work speeds of gear and different loading torques were investigated.

Cavitation is common in traditional torque converters whose blades are designed by beam theory; the blade curvature is discontinuous and cannot be analysed by functions. In this paper, the YJH265 torque converter is used as the prototype to reconstruct the stator blades with Joukowsky airfoil transformation. Computational Fluid Dynamics (CFD) is used analyse the flow field in the torque converter with the three-dimensional transient full flow channel. Combined with experiments, cavitation is found at the exit of the YJH265 torque converter stator. This is the same as the cavitation position of different torque converters studied by other scholars, and the flow state at the simulation outlet is high vacuum, boundary layer separation and high turbulent kinetic energy. Without changing the angle and chord length, the stator blades were reshaped and simulated with the optimised Joukowsky airfoil. As a result, the boundary layer separation phenomenon disappeared, the vacuum degree and turbulent kinetic energy were reduced, the torque ratio increased by 0.175 (5.6%), and the efficiency increased by 4.9%. To conclude, the optimised Joukowsky airfoil can be used in the design of stator blades, and its streamline is consistent with the fluid dynamics characteristics, which greatly reduces the probability of cavitation and improves the performance and service life of the torque converter.

This study investigated the effect of surface groove micro-texturing on hydrodynamic lubrication characteristics. All textured samples were processed by laser; non-textured reference samples were also created for comparison. Four types of surface groove patterns with different groove angles and groove depths were utilised. Different rotational speeds and gaps were used in the experiment to explain the relationship between the load-carrying capacity and the groove texture parameters under different conditions. The results suggested that the load-carrying capacity was greatly influenced by the operational conditions and that the samples with surface groove textures generated a larger hydrodynamic lift force than the non-textured samples.