Appeal No. 2005-0618 Page 4
Application No. 09/760,017
Claim 1, the only independent claim on appeal, reads as follows:
A motorized reduction gear comprising:
a rotor provided with a rotor shaft bearing a commutator including a body
having an inner surface mounted on said shaft and an opposing outer surface,
and a reduction gearbox containing a gearwheel engaged with a worm of said
shaft, and a magnetic ring mounted on said shaft in order that a number of
rotations of said shaft can be counted, and wherein said magnetic ring is
attached on said outer surface of said body of said commutator.
Schechinger's invention is directed to an electromotive drive device, in particular
for a motor vehicle, with a commutator motor and a drive shaft, with which at least one
Hall sensor and a magnet wheel arranged on the drive shaft cooperate in order to
detect the speed and direction of rotation. Figure 1 shows electromotive drive 10
having a stator housing 12, at least one permanent magnet 13 and drive shaft 14. Shaft
14 carries a commutator 15 and an armature 16, which can turn in the magnetic field of
permanent magnet 13. Brush contacts 17 slide against commutator 15 by which means
a current flows in the direction of the winding. A pulse output device 30 is attached to
the drive shaft 14 between commutator 15 and structure 20, and is actively connected
to a Hall switch 31. Hall switch 31 is connected to structure 20 by means of support 32.
Pulse output device 30 consists of spacing bushing 33, which is rigidly attached to drive
shaft 14 and magnet wheel 34 fitted on spacing bushing 33 by clnmping or adhesion.
Spacing bushing 33 operates as a short-circuit ring for the magnetic circuit, which is
used to amplify the magnetic field. Figure 2 of Schechinger illustrates a modification of
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