Design Optimization Methods for Forced Lubrication System Used in Automotive Transmissions

Abstract

Lubrication has been a major area of interest in engineering. Especially in vehicle transmissions, lubrication plays a very crucial role because gears and bearings are constantly subjected to heavy loads. Proper lubrication is essential for maintaining system performance and ensuring endurance life. Insufficient lubrication can lead to excessive wear, increased friction, and eventually, failures in the transmission components. However, excess lubrication can result in power losses due to the resistance offered by the excessive lubricant. Therefore, achieving effective lubrication using optimized lubrication system design is vital for ensuring the longevity and efficiency of the transmission system. Majorly, two types of lubrication methods are used in transmissions: splash lubrication and forced lubrication. This article focuses on forced lubrication, where the lubrication system actively delivers the required flow of lubricant to specific locations within the transmission. Pump outflow, orifice diameters, and channel dimensions are a few of the critical design parameters of the forced lubrication system. This article presents two design optimization methods: one using ANSYS DX (3D) and the other using GT-Suite (1D) tool. In the 3D method, ANSYS Fluent is used for CFD (computational fluid dynamics) simulations and subsequently ANSYS DesignXplorer (DX) is leveraged for design optimization. Predictions from CFD simulations are validated against physical test data and show good agreement (>90% match for flow rate). GT-SUITE is used in the 1D method, which is validated with predictions from 3D CFD method. The optimized designs obtained from both methods are effective in achieving the desired flow rate distribution, demonstrating their reliability. The ANSYS DX method provides an advantage in terms of reduced overall turnaround time (50% less) for the optimization. On the other hand, co-simulation (CFD+1D) approach can prove beneficial if it is required to perform minor routing changes on the lube system layout.