BMW I01 Product Information page 45

I01￿High-voltage￿Components
3.￿Electric￿Motor
The￿parking￿lock￿module￿functions￿at￿a￿driving￿shaft.￿At￿the￿end￿of￿the￿driving￿shaft￿there￿is￿a￿bar￿which
is￿turned￿about￿70￿degrees￿by￿the￿revolution￿of￿the￿driving￿shaft.￿As￿a￿result,￿the￿parking￿lock￿pawl￿is
inserted￿into￿the￿parking￿lock￿gear￿and￿the￿transmission￿input￿shaft￿is￿blocked.￿By￿resetting￿the￿bar
the￿parking￿lock￿pawl￿is￿released￿again,￿pulled￿from￿the￿parking￿lock￿gear￿by￿the￿return￿spring￿and￿the
transmission￿input￿shaft￿is￿unlocked.￿The￿driving￿shaft￿is￿held￿in￿the￿two￿positions,￿"engaged"￿and
"disengaged",￿by￿a￿fixing￿element.￿The￿fixing￿element￿locks￿into￿the￿respective￿recesses￿at￿the￿cam
disc.￿The￿rod￿cannot￿be￿moved￿from￿these￿positions￿by￿movements￿or￿forces￿from￿the￿transmission.
Both￿positions￿are￿stable￿without￿the￿supply￿of￿auxiliary￿power.￿It￿is￿also￿said:
The￿parking￿lock￿of￿the￿I01￿is￿bi-stable.￿This￿means￿it￿requires￿external￿energy￿in￿order￿to￿change￿the
condition￿of￿the￿parking￿lock.
Energy￿is￿required￿for￿both￿disengaging￿and￿engaging￿the￿parking￿lock.￿In￿BMW￿vehicles￿with￿a
conventional￿engine￿and￿automatic￿transmission￿energy￿is￿only￿required￿for￿disengaging￿the￿parking
lock.
The￿actuator￿of￿the￿parking￿lock￿is￿a￿direct￿current￿electric￿motor￿with￿gear/worm￿wheel￿transmission
and￿two￿position￿sensors.￿All￿these￿parts￿are￿located￿in￿the￿housing￿and￿form￿one￿unit.￿The￿parking
lock￿module￿is￿secured￿using￿three￿raised￿head￿Torx￿screws￿on￿the￿transmission￿housing￿and￿for￿now
is￿not￿replaced￿in￿BMW￿Service.
The￿parking￿lock￿module￿is￿connected￿to￿the￿parking￿lock￿via￿a￿multi-tooth￿connection￿of￿the￿actuator/
driving￿shaft￿at￿the￿transmission￿interface.￿Attention:￿The￿vehicle￿must￿be￿secured￿against￿rolling
away￿by￿other￿measures￿(e.g.￿by￿operating￿the￿parking￿brake￿or￿positioning￿a￿wedge).
The￿electric￿motor￿in￿the￿parking￿lock￿module￿is￿activated￿directly￿by￿an￿output￿stage￿in￿the￿electrical
machine￿electronics.￿The￿output￿stage￿is￿current-limited￿to￿protect￿against￿damage￿by￿a￿short￿circuit.
In￿order￿not￿to￿overload￿the￿electric￿motor,￿the￿power￿consumption￿is￿also￿measured￿and￿a￿current
limitation￿performed￿in￿the￿software￿of￿the￿electrical￿machine￿electronics.
The￿electric￿motor￿is￿supplied￿with￿current￿until￿the￿position￿sensors￿display￿that￿the￿parking￿lock￿has
adopted￿the￿desired￿condition.￿The￿position￿sensors￿work￿according￿to￿the￿hall-effect￿principle￿and
record￿the￿movement￿in￿the￿transmission￿of￿the￿parking￿lock￿module.￿As￿the￿function￿of￿the￿parking
lock￿is￿relevant￿for￿safety,￿two￿redundant￿position￿sensors￿are￿used￿to￿achieve￿the￿requested￿reliability.
If￿a￿sensor￿signal￿fails￿due￿to￿a￿fault,￿an￿active￿engaging￿or￿disengaging￿procedure￿can￿be￿completed￿as
a￿result￿of￿the￿redundancy.￿The￿position￿sensors￿generate￿signals￿which￿are￿evaluated￿by￿the￿electrical
machine￿electronics.
As￿the￿position￿sensors￿record￿the￿movement￿of￿the￿electric￿motor￿in￿the￿parking￿lock￿module￿and￿not
the￿movement￿of￿the￿actual￿parking￿lock￿mechanics,￿an￿initialization￿has￿to￿be￿performed￿as￿a￿one-off
so￿that￿a￿conclusion￿can￿be￿drawn￿about￿the￿condition￿of￿the￿parking￿lock￿from￿the￿sensor￿signals.
The￿following￿graphic￿shows￿the￿electrical￿structure￿of￿the￿parking￿lock￿module￿and￿the￿electrical
connection￿for￿the￿electrical￿machine￿electronics.
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