Eco-friendly Product Development at SNR Roulements - NTN

NTN TECHNICAL REVIEW No.772009
Consequently, lower torque and mitigation of heat
buildup have been achieved. Fig. 17 illustrates a
cross-sectional plan of our seal, and a view of the
contact area of the slinger. Micro-pores present in this
contact area help form an oil film between the seal lip
and slinger, and the oil film reduces friction on the seal
lip. Furthermore, these micro-pores prevent wear
caused by ingress and trapping of foreign matters.
3.4.2 Performance of tribological effect-capable seal
Figs. 18 and 19 show running torque and test
results of a muddy water bearing life test with
conventional seal and our newly developed tribological
effect-capable seal. Owing to reduced resistance on
seal, the running torque has decreased by 11%, and
the muddy water bearing life has increased by 22%.
Enlarged view of
contact area
on slinger
Micro-pores
3.5 Automotive suspension bearings
To be able to operate without problems under
severe operating conditions (environments such as
muddy water), a sealed strut bearing needs to feature
improved reliability and sealing performance. In
challenging this issue, SNR has developed a unique
low torque sealed strut bearing complete with a floating
seal in order to satisfy requirements for both an
improvement in running torque and sealing
performance (Fig. 21).
3.5.1 Features of sealed strut bearings
Muddy water resistance of a bearing is governed by
lip performance of its seal. Therefore, it is important to
develop a seal that is capable of satisfying both better
sealing performance and stabler running torque
performance. To address this challenge, we have
recently developed a novel low torque sealed strut
bearing complete with a floating seal. Fig. 20 shows a
conventional design, and Fig. 21 illustrates our new
design. For comparison purpose, Fig. 22 shows a
structure of a different design, that is, an overmolded
lip seal.
Fig. 17 Seal shape on the slinger
Torque Nm
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Conventional
design
Tribological
effect-capable seal
11% reduction
in running
torque
Seal area
Bearing area
Fig. 20 Usual design
Fig. 18 Comparison of rotational friction between
development seal and current one
Muddy water bearing life h
700
600
500
400
300
200
100
0
Conventional design
Tribological
effect-capable seal
22%
Fig. 19 Comparison of muddy water resistance between
development seal and current one
Fig. 21 SNR design: floating seal
Fig. 22 Competitor design: overmolded lip seal
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