Reducing design turnaround time and costs by giving designers more insight into the oil flow path

About the customer

FINEST Transmission Technology Hebei Co. Ltd (FINEST) is a comprehensive enterprise focusing on E-drive systems. FINEST designs and manufactures transmission systems for both pure electric vehicles (EV) and hybrid vehicles (HEV), and its products meet the needs of vehicles from subcompact (A0) class to medium and large sport utility vehicles (SUVs). The research and development (R&D) center covers both domestic and foreign vehicle transmission systems and can perform simulations and experiments from the component level to the full-vehicle level.

Their challenge

FINEST needed a way to troubleshoot gearbox mechanical failures (such as pitting, erosion, and peeling), mostly caused by insufficient lubrication. In addition, since e-drive speed can reach up to 20,000 revolutions per minute (RPM), FINEST needs to be able to properly calculate churning losses. It must also consider windage effects, oil volume, and the amount of air bubbles (aeration) present in oil.

Snapshot of transient oiling in gearbox (FINEST transmission products).

Our solution

To address its problems, FINEST adopted Siemens solutions, which combine smooth particle hydrodynamics (SPH) with graphics processing unit (GPU) hardware to streamline innovation and problem-solving. FINEST primarily used Simcenter™ Nanofluid™ software and Simcenter Simlab™ software throughout the process. With Simcenter Simlab, a powerful preprocessing solution, the team created smoothed-particle hydrodynamics (SPH) models from complex raw CAD geometry in less than a day and was able to define physical and numeric parameters. In addition, the team could submit calculations directly from local and remote GPU servers. And although physical testing is still an important part of the product design process, Simcenter Nanofluid gave the FINEST designers more insight into complex flow phenomena and helped the teams answer vital questions such as:

1. Where are oil droplets from oil sumps and injectors coming from, and where are they going?
2. Why is the oil path not flowing as intended?
3. How can we address an oil collector installed at an inclined angle?
4. How can we address and mitigate potential oil leaks from breathe holes?

Moreover, Simcenter Nanofluid allowed the team to assess multiple scenarios. The solution enabled FINEST to determine how volatile high RPM flow fields are, how gear rotation pumps air bubbles into the lubrication oil, and more. This augmented the physical testing process with unprecedented power and accuracy.

Simcenter Nanofluid allowed the team to assess multiple different scenarios such as the time averaged oil fraction distribution.

Results

With Siemens solutions, FINEST can reduce physical gearbox testing while increasing the efficiency of its computational fluid dynamics (CFD) simulations to include richer, more detailed oiling information including flow rate, hydrodynamic torque, fluid contact time, heat transfer coefficient, and more. Siemens solutions also helped FINEST significantly reduce design turnaround time and reduced costs by giving designers more insight into other aspects such as oil flow path, lubrication and cooling effects, and oil volume. Now, FINEST can design better, more efficient gearboxes in less time and at lower costs.

“In the past, gearbox oiling mainly relied on physical tests and engineer experience, and the design cycle was long,” says Cui Jin, CAE simulation engineer FINEST. “Using the latest Simcenter CFD simulation technology, engineers have a deeper understanding of the complex two-phase flow phenomenon in the gearbox, which helps us optimize our products.”