BMW I01 Product Information page 89

I01￿High-voltage￿Components
5.￿High-voltage￿Battery￿Unit
5.2.3.￿Vent￿hole
The￿vent￿hole￿has￿two￿tasks.￿The￿first￿task￿of￿the￿vent￿hole￿is￿to￿offset￿large￿pressure￿differences
between￿the￿inside￿and￿outside￿of￿the￿high-voltage￿battery￿unit.￿Such￿pressure￿differences￿can￿only
arise￿in￿the￿event￿of￿a￿damaged￿battery￿cell.￿For￿safety￿reasons￿the￿housing￿of￿the￿cell￿module￿with￿the
damaged￿battery￿cell￿is￿opened￿to￿reduce￿the￿pressure.￿The￿gases￿are￿initially￿located￿in￿the￿housing
of￿the￿high-voltage￿battery￿unit.￿From￿there￿they￿can￿be￿transported￿outwards￿via￿the￿vent￿hole.
The￿second￿task￿of￿the￿vent￿hole￿is￿to￿transport￿outwards￿condensate￿arising￿in￿the￿inside￿of￿the￿high-
voltage￿battery￿unit.￿Besides￿the￿technical￿components,￿there￿is￿also￿air￿inside￿the￿high-voltage￿battery
unit.￿If￿the￿air￿or￿the￿housing￿is￿cooled￿by￿a￿lower￿ambient￿temperature￿or￿by￿a￿refrigerant￿through￿the
activation￿of￿the￿air￿conditioning￿function,￿some￿of￿the￿water￿vapor￿from￿the￿air￿condenses.￿This￿means
small￿amounts￿of￿liquid￿water￿can￿form￿in￿the￿inside￿of￿the￿high-voltage￿battery￿unit.￿This￿has￿no￿affect
on￿the￿function.￿During￿the￿next￿heating￿of￿the￿air￿or￿the￿housing￿the￿water￿evaporates￿again￿and,￿at￿the
same￿time,￿the￿pressure￿in￿the￿housing￿rises￿slightly.￿The￿vent￿hole￿permits￿pressure￿compensation￿by
allowing￿the￿warm￿air￿to￿escape￿outwards.￿The￿water￿vapor￿in￿the￿air￿is￿also￿transported￿outwards￿and
also￿the￿previously￿liquid￿condensate.
To￿fulfil￿these￿tasks￿the￿vent￿hole￿has￿a￿permeable￿diaphragm￿for￿gases￿(and￿water￿vapor)￿and￿an
impermeable￿diaphragm￿for￿fluids.￿There￿is￿a￿two-piece￿cover￿located￿above￿the￿diaphragm￿with￿which
the￿diaphragm￿is￿protected￿against￿coarse￿dirt￿contamination.
Vent￿hole
Index
1
2
The￿venting￿unit￿can￿be￿replaced￿in￿Service￿as￿an￿entire￿unit.￿A￿replacement￿makes￿sense￿if￿the
venting￿unit￿is￿heavily￿contaminated￿or￿has￿suffered￿mechanical￿damage.
Explanation
Mounting￿bolts￿(x4)
Vent￿hole
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