Rotating angle detecting sensor
AssigneeNtn Corporation
InventorShoji Itomi
Life of this patent
Estimating the term…
Abstract
An angle detection error is prevented by using a columnar permanent magnet that is radially double-pole-magnetized as a rotating angle detecting sensor while preventing a gap between a plurality of magnetic sensors and an end face of the permanent magnet from being narrowed. The permanent magnet is a ferrite magnet or an alnico magnet having a diameter of 4 mm to 20 mm, and an axial length of 3 mm to 5 mm. The plurality of magnetic sensors detects radial magnetic flux densities at positions axially spaced 0.5 mm to 3.0 mm apart from a central portion of the permanent magnet, the central portion having a diameter equal to or smaller than 20% of the magnet diameter to make it possible to perform detection in a range in which a distribution curve of a radial magnetic flux density has a moderate inclination.
Claims11
A rotating angle detecting sensor comprising:
- a columnar permanent magnet;
- and a plurality of magnetic sensors arranged entirely within a circle axially spaced apart from an end face of the permanent magnet, the permanent magnet being formed with a uniform material, having a columnar shape, and being radially double-pole-magnetized;
- wherein the permanent magnet is formed by a ferrite magnet or an alnico magnet having a diameter of 4 mm to 20 mm and an axial length of 3 mm to 5 mm,
- wherein the plurality of magnetic sensors is arranged to detect a radial magnetic flux density at a position spaced 0.5 mm to 3.0 mm apart from a central portion of the permanent magnet, the central portion having a diameter equal to or smaller than 20% of the magnet diameter on the end face of the permanent magnet, and
- wherein the circle has a diameter equal to or smaller than 20% of the magnet diameter and is configured to be concentric with the permanent magnet.
Dependencies are inferred from the claim text.