NEW PRODUCTModel Based Development for BEV High-speed Ball Bearing
Reproduction of actual
operating conditions
without prototyping

Physical space

Cyber space

In recent years, bearing development has come torequire not only performance improvements such as
to systems, but also shortened development periods.
For this reason, JTEKT is actively using model-based
development (MBD) to reproduce development targets
using cyberspace-based models, which are then used to
conduct simulations for performing development andverification. In this paper, we will discuss the details ofour development performed on high-speed ball bearings
for BEV using MBD.

Image of MBD

Example of MBD Being Used for Development of High-speed Ball Bearings for BEV
As automotive electrification accelerates, rolling bearings are being required to be capable of high-speed rotation andwith lower torque. Because centrifugal force acts on each part of the bearing during rotation, operating conditions areespecially harsher than usual during high-speed rotation. In order to develop bearings that do not suffer damage or seizure
during high-speed rotation, JTEKT is accelerating its development of MBD technology.
①Shortening development periods by predicting bearing service life during high-speed rotation
JTEKT has developed its own specialized analysis program for bearing design that enables bearing service life and cage
durability to be verified in advance.
・Bearing service life and temperature increases can be predicted by accurately estimating the contact stress applied toraceways when loads act upon the bearing.
・Cage durability can be verified by accurately estimating the force that acts upon the cage due to the lead or lag ofballs during high-speed rotation.
・Specialized modules for each bearing type have been developed that enable new bearings to be developed quickly.
・Design study periods for newly developed bearings have been halved in comparison to conventional study periods.

Ball contactstressContract stress distribution inside a bearing(static simulation)

Force acting
on cage

Force acting
on bearing ring

Distribution of force acting on cage
(dynamic simulation)

Example of BEV unit model creation

Example of using a specialized analysis program for bearing design

JTEKT CORPORATION88

JTEKT ENGINEERING JOURNAL English Edition No. 1019E (2023)

NEW PRODUCT②Contributing to the optimization of lubrication system design by developing a method of predicting lubricant flow
during high-speed operation
When performing MBD for bearings, it is necessary to understand the lubrication conditions inside the bearing andconstruct a fluid simulation model accordingly. For this purpose, we developed a test equipment capable of observing theflow of lubricant inside the bearing during operation*1.
This enabled us to successfully observe the flow of lubricants at a high rotation speed of 20 000 min1, a world first,
while also enabling us to observe the thin film lubrication state that occurs only at high-speed rotation*2.
・We constructed a new simulation model for lubricant flow analysis by applying correlations with observation results.
・Being able to predict the amount of lubricant that flows into the bearing in advance enables us to greatly assist in thelubrication system design processes for various customer units.
*1 Jointly developed with Toyota Central R&D Labs, Inc.
*2 In-house investigation results from December 2021

…Lubricant
1Transparent outer ring
made of quartz glass

20 000 min rotation speedBallOuter ring raceway surfaceRolling direction

CameraMotor

Observation results for lubricant flow

Observation
rangeWeights
Test equipment for visualizing lubricant flow
[Provided by Toyota Central R&D Labs, Inc.]

Simulation results for lubricant flow analysis

Method used to predict lubricant flow

By utilizing such MBD technology, we have developed a high-speed rotating ball bearing for BEV capable of 1.85
million d mn *3 using grease lubrication.
*3 “d mn ” is an indicator that expresses bearing rotational performance using the equation “ball pitch circle diameter(mm) × rotation speed (min1).”*Details of development examples are shown in “Development of Grease-lubricated High-speed Bearing” shown on
page 82 of this report.

Contributions to Customers①Being able to deliver high-quality bearing products in short amount of time enables us to contribute in shortening
customer development periods.
②We can now propose bearing specifications and lubrication system designs that enhance customer unit performance.
(Engineering Planning Dept., Industrial and Bearing Business Unit)

JTEKT CORPORATIONJTEKT ENGINEERING JOURNAL English Edition No. 1019E (2023)

89