| 摘要 |
An encoder structure includes a sensor head unit 6 installed in an irrotational part, a rotative magnetic ring unit 4 that is positioned close to the sensor head unit 6 and has a north pole and a south pole arranged alternately on a circumference thereof, and a groove unit 7 formed in at least one of spaces between the north pole and the south pole located on a surface of the magnetic ring unit 4. Thus, deposits such as iron particles are easily drained away with muddy water because a part where the iron particles tend to be accumulated along a magnetic flux functions as a groove-like path. Additionally, accumulated iron particles remain inside the groove unit 7 that is concave shaped. Accordingly, prevention of damage to the sensor head unit 6 is achieved. |
