US 12,460,945 B2
Magnetic drum and magnetic encoder with the same
Wenhao Cheng, Guangdong (CN); Yan Wang, Guangdong (CN); Muyang Cheng, Guangdong (CN); Huaiyin Meng, Guangdong (CN); and Xin Wang, Guangdong (CN)
Assigned to SHENZHEN RADIMAG MAGNETS CO., LTD., Shenzhen (CN)
Appl. No. 18/557,012
Filed by Shenzhen Radimag Magnets Co., Ltd., Guangdong (CN)
PCT Filed Dec. 10, 2021, PCT No. PCT/CN2021/137085
§ 371(c)(1), (2) Date Oct. 24, 2023,
PCT Pub. No. WO2022/237150, PCT Pub. Date Nov. 17, 2022.
Claims priority of application No. 202110522321.8 (CN), filed on May 13, 2021.
Prior Publication US 2024/0230374 A1, Jul. 11, 2024
Int. Cl. G01D 5/12 (2006.01)
CPC G01D 5/12 (2013.01) 13 Claims
OG exemplary drawing
 
1. A magnetic drum, comprising:
a permanent magnetic ring body, wherein the permanent magnetic ring body comprises an inner ring wall and an outer ring wall; the inner ring wall has a single first polarity, the outer ring wall is a single second polarity, and the first polarity is opposite to the second polarity; the inner ring wall and the outer ring wall are coaxially arranged around an axis of the permanent ring wall body; a plurality of protrusions are uniformly provided on the outer ring wall around the axis of the permanent ring wall body and are projected on a radial plane of the permanent magnetic ring body; and, a plurality of recesses are uniformly formed on the radial plane of the permanent magnetic ring body between the plurality of protrusions and each recess of the plurality of the recessed is formed between any two adjacent protrusions; and wherein a maximum circumferential width of a radial opening of the recess is L, a radial height of the protrusion is H, and L>0.1H; and the plurality of protrusions should have a central symmetrical structure respect to the axis of the permanent magnetic ring body, so as to satisfy requirements the protrusions as a magnetic signal source of the encoder; and the protrusions and recesses have the same magnetic poles; and strength of a magnetic field at the protrusions is higher than the strength of the magnetic field at the recesses; and on the outer surface of the magnetic drum, a waveform diagram of the magnetic field is formed on the outer surface.