| 摘要 |
It is described a magnetic field differential sensor system for measuring rotational movements of a shaft. The described magnetic field sensor system (200) comprises (a) a biasing magnet (210, 510) configured for generating a biasing magnetic field; (b) a magnetic wheel (230) having a wheel axis and a circumferential surface which comprises a regular structure of teeth (231) and gaps (232) arranged in an alternating manner, wherein (i) the magnetic wheel (230) is attachable to the shaft and (ii) the magnetic wheel (230) can be magnetized by the biasing magnetic field; and (c) a magnetic sensor arrangement (220) comprising four magnetic sensor elements (221, 222, 223, 224) being connected with each other in a Wheatstone bridge configuration. Respectively two of the magnetic sensor elements (221, 222, 223, 224) are assigned to one half bridge of the Wheatstone bridge. Further, the four magnetic sensor elements (221, 222, 223, 224) are arranged within an y-z plane, wherein an x-axis, a y-axis and a z-axis define an orthogonal Cartesian coordinate system in which (i) the x-axis is oriented parallel with the wheel axis of the magnetic wheel (230), (ii) the y-axis is oriented tangential to the circumferential surface of the magnetic wheel (230), and (iii) the z-axis is the symmetry line through the center of the biasing magnet (210, 510) and the center of the magnetic wheel (230). The magnetic sensor elements can be hall sensor elements or magnetoresistive sensor elements (221, 222, 223, 224). |
| 主权项 |
1. A magnetic field sensor system configured to measure rotational movements of a shaft, the magnetic field sensor system comprising:
a biasing magnet configured to generate a biasing magnetic field; a magnetic wheel having a wheel axis and a circumferential surface which comprises a regular structure of teeth and gaps arranged in an alternating manner, wherein the magnetic wheel is attachable to the shaft and can be magnetized by the biasing magnetic field; and a magnetic sensor arrangement comprising four magnetic sensor elements being connected with each other in a differential Wheatstone bridge, wherein two of the four magnetic sensor elements are respectively assigned to each half bridge of the differential Wheatstone bridge configured to measure a difference between y-components of magnetic fields for each half bridge, the four magnetic sensor elements are arranged within an y-z plane, an x-axis, a y-axis and a z-axis define an orthogonal Cartesian coordinate system in which the x-axis is oriented parallel with the wheel axis of the magnetic wheel, the y-axis is oriented tangential to the circumferential surface of the magnetic wheel, the z-axis is a symmetry line through a center of the biasing magnet and a center of the magnetic wheel, and each of the four magnetic sensor elements has a barber pole structure forming an angle of substantially 45° with respect to the z-axis. |
