Patent ID: 9722480
Date: 2017-08-01
CPC Classifications: A61B,H01F,H02K

Claim:
1. A linear drive comprising: a ring-shaped stator having a center axis, the stator further comprising: a magnetic coil, a first ring-shaped stator pole shoe and a second ring-shaped stator pole shoe, each pole shoe being at one side of the coil, a magnetic member enclosing the coil in radial direction a first field sensor in axial direction next to the coil on the side of the first stator pole shoe, a second field sensor in axial direction next to the coil on the side of the second stator pole shoe, a hollow armature being moveable in axial direction in the stator, the armature further comprising: a first ring-shaped permanent magnet and a second ring-shaped permanent magnet, the permanent magnets being polarized axially in opposite directions, a ring-shaped center armature pole shoe between the two permanent magnets, a ring-shaped first outer armature pole shoe at a side of the first permanent magnet, said side being opposite to the middle armature pole shoe in axial direction, and a ring-shaped second outer armature pole shoe at a side of the second permanent magnet, said side being opposite to the middle armature pole shoe in axial direction, wherein at least a part of the magnetic flux of the first outer armature pole shoe and the second outer armature pole shoe goes through at least one of the field sensors.