Gear tooth sensor with improved resolution and stability
First Claim
1. A gear tooth sensor for sensing one or more gear teeth on a ferrous target wheel, said target wheel being rotatably mounted relative to a predetermined axis of rotation, the sensor comprising:
- a magnet for generating magnetic flux having opposing north and south magnetic pole faces defining a lateral surface therebetween and a magnetic axis generally perpendicular to said opposing pole faces of said magnet;
a single magnetic flux responsive element which provides an output signal as a function of said magnetic flux, said magnetic flux responsive element having a predetermined sensing plane that is sensitive to said magnetic fluxa first flux concentrator at least partially disposed in a plane generally parallel to said magnetic axis and at least partially disposed adjacent to said lateral surface; and
a carrier for carrying said magnet and said magnetic flux responsive element relative to said ferrous target wheel such that said magnet is disposed at a predetermined air gap relative to the periphery of said ferrous target wheel and said magnetic flux responsive element is offset from said center line of said magnet forming a zero speed sensor, said magnetic flux responsive element being disposed to at least partially overlap one of said opposing pole faces of said magnet.
6 Assignments
0 Petitions
Accused Products
Abstract
A gear tooth sensor having increased sensitivity and temperature tolerance enables relatively small ferrous targets to be detected, which lends itself for use in relatively compact applications, such as the sensing of an automotive cam shaft drive wheel. All of the embodiments include a magnet having opposing north and south pole faces and a single input Hall effect IC which defines a sensing plane, and may include one or more flux concentrators. In one embodiment the sensor is configured such that the magnet is disposed adjacent the periphery of the target wheel such that the magnetic axis is generally parallel to the direction of travel of the ferrous target at an instant when the ferrous target is adjacent the magnet. In this embodiment, the Hall effect IC and flux concentrator are disposed adjacent one side of the ferrous target wheel and at least partially below the magnet. In one alternate embodiment of the invention, the magnet, Hall effect IC and flux concentrator are all aligned and disposed such that the magnetic axis is generally parallel to the direction of travel of the ferrous target at an instant when the ferrous target is adjacent the magnet. As such, the alternate embodiment is adapted to be configured relative to the ferrous target wheel for different applications. In both embodiments, additional flux concentrators can be included for adjusting the operate points of the Hall effect IC'"'"'s. In yet other embodiments, the sensor is configured such that the sensing plane of the IC is generally perpendicular to the magnetic axis.
62 Citations
20 Claims
-
1. A gear tooth sensor for sensing one or more gear teeth on a ferrous target wheel, said target wheel being rotatably mounted relative to a predetermined axis of rotation, the sensor comprising:
-
a magnet for generating magnetic flux having opposing north and south magnetic pole faces defining a lateral surface therebetween and a magnetic axis generally perpendicular to said opposing pole faces of said magnet; a single magnetic flux responsive element which provides an output signal as a function of said magnetic flux, said magnetic flux responsive element having a predetermined sensing plane that is sensitive to said magnetic flux a first flux concentrator at least partially disposed in a plane generally parallel to said magnetic axis and at least partially disposed adjacent to said lateral surface; and a carrier for carrying said magnet and said magnetic flux responsive element relative to said ferrous target wheel such that said magnet is disposed at a predetermined air gap relative to the periphery of said ferrous target wheel and said magnetic flux responsive element is offset from said center line of said magnet forming a zero speed sensor, said magnetic flux responsive element being disposed to at least partially overlap one of said opposing pole faces of said magnet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 17, 18, 19, 20)
-
-
12. A sensor for sensing one or more ferrous targets, the sensor comprising:
-
a magnet for generating magnetic flux having opposing north and south magnetic pole faces defining a lateral surface therebetween and a magnetic axis generally perpendicular to said opposing pole faces of said magnet; a first flux concentrator at least partially disposed in a plane generally parallel to said magnetic axis and at least partially disposed adjacent to said lateral surface; and a single magnetic flux responsive element which provides an output signal as a function of said magnetic flux, said magnetic flux responsive element having a predetermined sensing plane responsive to said magnetic flux, wherein said magnetic flux responsive element is offset from said centerline of said magnet forming a zero speed proximity sensor, said magnetic flux responsive element being disposed to at least partially overlap one of said opposing pole faces of said magnet. - View Dependent Claims (13, 14, 15, 16)
-
Specification