Rotary encoder
A rotary encoder ( 1 ) is provided, including a shaft (W) connected to and drivable by an external shaft, a first gear unit (G 1 ) and a second gear unit (G 2 ), each following rotations of the shaft (W). Both gear units (G 1 , G 2 ) (G 1 and G 2 ) are drivable independently of one another by the shaft (W), a first gear stage (G 1 S 1 ) of the first gear unit (G 1 ) has a first detection unit (E 1 ), and a gear stage (G 2 S 2 ) downstream of a first gear stage (G 2 S 1 ) of the second gear unit (G 2 ) has a second detection unit (E 2 ). An evaluation unit derives the angular position from signals of the detection units (E 1 , E 2 ) and compares the rotations of the first gear stage (G 1 S 1 ) and the downstream gear stage (G 2 S 2 ) for plausibility, taking into account a known ratio of the rotation of the first gear stage (G 1 S 1 ) to the rotation of the downstream gear stage (G 2 S 2 ).
1. A rotary encoder ( 1 ) for determining an angular position of a shaft (W), comprising:
the shaft (W), which is connected to an external shaft and can be driven by the external shaft;
a first gear unit (G 1 ) and a second gear unit (G 2 ) which each follow rotations of the shaft (W), wherein the first and second gear units (G 1 , G 2 ) are driven independently of each other by the shaft (W);
wherein a first gear stage (G 1 S 1 ) of the first gear unit (G 1 ) has a first detection unit (E 1 ), and a second gear stage (G 2 S 2 ) of the second gear unit (G 2 ), which is downstream of a first gear stage (G 2 S 1 ) of the second gear unit (G 2 ), has a second detection unit (E 2 ); and
an evaluation unit for deriving the angular position from signals of the first and second detection units (E 1 , E 2 ), wherein the evaluation unit compares the rotations of the first gear stage (G 1 S 1 ) of the first gear unit (G 1 ) and the second gear stage (G 2 S 2 ) of the second gear unit (G 2 ) for plausibility, taking into account a known ratio of the rotation of the first gear stage (G 1 S 1 ) of the first gear unit (G 1 ) to the rotation of the second gear stage (G 2 S 2 ) of the second gear unit (G 2 ), wherein the ratio is greater than 2 to 1.
2. The rotary encoder ( 1 ) according to claim 1 , wherein the first gear stage (G 2 S 1 ) of the second gear unit (G 2 ) has no detection unit.
3. The rotary encoder ( 1 ) according to claim 1 , wherein each of the first and second detection units (E 1 , E 2 ) comprises a magnet and a Hall sensor.
4. The rotary encoder ( 1 ) according to claim 1 , wherein the first and second gear units (G 1 and G 2 ) each comprise a plurality of cascaded gear stages (G 1 S 1 , G 2 S 1 , G 2 S 2 , G 2 S 3 ).
5. The rotary encoder ( 1 ) according to claim 4 , wherein the first gear stages (G 1 S 1 , G 2 S 1 ) each form a first gear stage of the respective cascade of the first and second gear units (G 1 and G 2 ) and are arranged directly on the shaft (W).
6. The rotary encoder ( 1 ) according to claim 4 , wherein the first gear stages (G 1 S 1 , G 2 S 1 ) are arranged at any desired position, in particular at a distance from the shaft (W), in the cascading of the first and second gear units (G 1 , G 2 ).
7. The rotary encoder ( 1 ) according to claim 6 , wherein in both cascading of the first and second gear units (G 1 , G 2 ) only the gear stage (G 2 S 1 ) of the second gear unit (G 2 ), which is determined as the first gear stage, has no detection unit.
8. The rotary encoder ( 1 ) according to claim 2 , wherein the first gear unit (G 1 ) forms a single-stage gear unit whose single gear stage (G 1 S 1 ) is provided with the first detection unit (E 1 ), and the second gear unit (G 2 ) forms at least two gear stages (G 2 S 1 , G 2 S 2 , G 2 S 3 ), wherein no detection unit is assigned to the first gear stage (G 2 S 1 ) of the second gear unit (G 2 ) and the second gear stage of the second gear unit (G 2 ) is provided with the second detection unit (E 2 ).
9. The rotary encoder ( 1 ) according to claim 1 , wherein the evaluation unit checks whether the angular position of the second gear stage (G 2 S 2 ) of the second gear unit (G 2 ) changes according to the known ratio of the rotations to the angular position of the first gear stage (G 1 S 1 ) of the first gear unit (G 1 ), or whether the angular position of the second gear stage (G 2 S 2 ) of the second gear unit (G 2 ) does not change in any proportion to, in particular completely independently of, an angular position change of the first gear stage (G 1 S 1 ) of the first gear unit (G 1 ).
10. The rotary encoder ( 1 ) according to claim 1 , wherein each of the gear stages (G 1 S 1 , G 2 S 1 , G 2 S 2 , G 2 S 3 ) itself consists of cascaded gear wheels and is separated from a downstream one of the gear stages means of an output gear wheel (Z 1 , Z 21 , Z 22 , Z 23 ), which for the respective gear stage delivers a specified output speed to the downstream one of the gear stages (G 2 S 2 , G 2 S 3 ).
11. The rotary encoder ( 1 ) according to claim 10 , wherein the output gear wheel (Z 1 ) of the first gear stage (G 1 S 1 ) of the first gear unit (G 1 ) and the output gear wheel (Z 22 ) of the second gear stage (G 2 S 2 ) of the second gear unit (G 2 ) are equipped with the first and second detection units (E 1 , E 2 ), respectively, and the output gear wheel (Z 21 ) of the first gear stage (G 2 S 1 ) of the second gear unit (G 2 ) has no detection unit.