Position sensor, designed in particular for detecting a steering column torsion
The invention concerns a position sensor, designed in particular for detecting a steering column torsion, consisting of a first magnetic structure including a plurality of magnets and a second magnetic structure including two ferromagnetic rings ( 6, 7 ) having a plurality of teeth ( 11, 12 ) and defining an air gap wherein is placed at least a magneto-sensitive element ( 15 ), the two magnetic structures being respectively integral with two parts in relative rotation. The invention is characterised in that the two ferromagnetic rings ( 6, 7 ) are nested and have each a substantially tubular part forming axially oriented teeth ( 11, 123 ) connected by a flux-closing zone ( 13, 14 ), the detecting air gap being delimited by said flux-closing zones.
1. A position sensor, comprising:
a first magnetic structure containing a plurality of magnets;
a second magnetic structure containing two ferromagnetic rings provided with a plurality of teeth and defining an air gap;
at least one magnetosensitive element placed in the air gap;
the first and second magnetic structures being integral respectively with two parts in relative rotation,
wherein the two ferromagnetic rings are intermeshed and each is provided with a substantially tubular part forming axially oriented teeth, connected by a flux-closure zone, the air gap being bounded by the flux-closure zones, and
wherein each magnet of the plurality of magnets has an edge that faces at least one tooth of the teeth of the two ferromagnetic rings.
2. A position sensor according to claim 1 , wherein the position sensor is configured for detecting torsion of a steering column.
3. A position sensor according to claim 1 , wherein the first magnetic structure is composed of a ferromagnetic tubular yoke provided with a plurality of tangential notches in which are seated thin magnets magnetized substantially radially in identical directions.
4. A position sensor according to claim 3 , wherein the thin magnets are in a form of radially magnetized tiles.
5. A position sensor according to claim 3 , wherein the thin magnets are in a form of parallelepiped magnets magnetized in a direction perpendicular to a plane of a main face.
6. A position sensor according to claim 1 , wherein a height of the teeth corresponds substantially to a height of the plurality of magnets.
7. A position sensor according to claim 1 , wherein at least one of the first and second magnetic structures is movable relative to the at least one magnetosensitive element.
8. A position sensor according to claim 1 , wherein the at least one magnetorestrictive element comprises N magnetosensitive elements, N corresponding to a number of phases of a brushless DC motor whose movement is controlled by the position sensor.
9. A position sensor according to claim 1 , wherein the two ferromagnetic rings are provided with flux-closure zones having a shape of transverse disks.
10. A position sensor according to claim 1 , wherein the two ferromagnetic rings are provided with flux-closure zones having a shape of half-toruses.
11. A position sensor according to claim 1 , wherein the two ferromagnetic rings are provided with flux-closure zones of tubular shape.
12. A position sensor according to claim 1 , wherein the two ferromagnetic rings are provided with flux-closure zones cut to form a plurality of teeth.
13. A position sensor according to claim 1 , wherein the two ferromagnetic rings are provided with flux-closure zones extending over 360° C.
14. A position sensor according to claim 1 , wherein the two ferromagnetic rings are provided with flux-closure zones extending over an annular sector corresponding substantially to a dimension of the magnetosensitive element.
15. A position sensor according to claim 1 , wherein the two ferromagnetic rings are composed of two movable toothed pieces and two fixed elements.
16. A torsion sensor comprising:
two rotating parts connected by an elastic test member;
a position sensor comprising two parts integral respectively with the two rotating parts,
the position sensor being composed of a first magnetic structure containing a plurality of radially magnetized magnets and a second magnetic structure containing two ferromagnetic rings provided with a plurality of teeth and defining an air gap, at least one magnetosensitive element placed in the air gap, the first and second magnetic structures being integral respectively with two parts in relative rotation, wherein the two ferromagnetic rings are intermeshed and each is provided with a substantially tubular part forming axially oriented teeth, connected by a transverse flux-closure zone, the air gap being bounded by the flux-closure zones, wherein each magnet of the plurality of magnets has an edge that faces at least one tooth of the teeth of the two ferromagnetic rings.