Fluxgate with laminar damping of the pendulum and method of assembling a fluxgate

Patent metadata

Field	Value
Publication number	US-9470502-B2
Application number	US-201214009787-A
Country	US
Kind code	B2
Filing date	Apr 19, 2012
Priority date	Apr 22, 2011
Publication date	Oct 18, 2016
Grant date	Oct 18, 2016

Abstract

Flow valve including a casing containing an electromagnetic assembly for detecting a magnetic field. The electromagnetic assembly is fixed to a pendulum suspended by an articulation from a plate of the casing. The casing contains a liquid for damping the movements of the pendulum. The pendulum includes a surface opposite the articulation which has a spherical cap shape and which extends facing a wall of the casing of complementary shape, defining a space having dimensions suitable for producing a laminar rolling of the damping liquid between them when the pendulum is in motion.

First claim

The invention claimed is:

1. A fluxgate comprising a casing containing an electromagnetic assembly for detecting a magnetic field, wherein the electromagnetic assembly is attached to a pendulum suspended from a plate of the casing by an articulation, wherein the casing contains a liquid for damping the movements of the pendulum, wherein the pendulum comprises, at the opposite end from the articulation, a surface which is in the shape of a spherical cap and extends facing a wall of the casing that has a form complementary to the form of the surface, defining a space having suitable dimensions to laminate the damping liquid between the surface and the wall when the pendulum moves.

2. The fluxgate as claimed in claim 1 , wherein said surface of the pendulum is bounded by a recessed surface portion in order to facilitate the entry of the damping liquid into the space.

3. The fluxgate as claimed in claim 2 , wherein the shape of the recessed surface portion is frustoconical.

4. The fluxgate as claimed in claim 1 , wherein said surface of the pendulum features, adjacent to its periphery, openings through which the damping liquid can escape.

5. The fluxgate as claimed in claim 1 , wherein the electromagnetic detection assembly comprises two uniaxial magnetometers arranged perpendicular to one another.

6. The fluxgate as claimed in claim 5 , wherein the magnetometers have end portions received in notches created in the pendulum.

7. The fluxgate as claimed in claim 1 , wherein the magnetometer assembly is connected to a connector, mounted on the plate, by wires gathered together in a twist.

8. The fluxgate as claimed in claim 7 , wherein the twist is in a spiral shape the axis of which is substantially normal to the plate.

9. The fluxgate as claimed in claim 7 , wherein the twist is shaped so as to substantially follow the axes of rotation of the articulation.

10. The fluxgate as claimed in claim 7 , wherein connections between the wires and the connector are embedded in a block of resin which is secured to the connector.

11. The fluxgate as claimed in claim 7 , wherein the twist has an end portion which is embedded in the block of resin.

12. The fluxgate as claimed in claim 1 , wherein the pendulum comprises an insert forming an inertial mass covered by thermoplastic material.

13. The fluxgate as claimed in claim 12 , wherein the pendulum is obtained by overmolding the thermoplastic material about the insert.

14. The fluxgate as claimed in claim 1 , wherein the selected damping liquid has a kinematic viscosity of 5 mm2/s at 25° C., a density of 0.91 at 25° C. and a freezing point of 65° C.

15. The fluxgate as claimed in claim 1 , wherein the articulation is connected to the plate and to the pendulum so as to allow the pendulum to move about two axes with two pivot connections for each axis.

16. A method for assembling a fluxgate in accordance with claim 1 , wherein the electromagnetic detection assembly comprises two uniaxial magnetometers arranged perpendicular to one another and having end portions received in notches created in the pendulum, wherein the casing comprises an attachment plate from which the pendulum is suspended, the method involving the step of suspending the pendulum from the attachment plate and a step of installing the magnetometers consisting of:
positioning the plate horizontally and allowing the pendulum to swing until it is stable,
positioning the ends of the magnetometers in the notches of the pendulum while keeping the two magnetometers in a horizontal position and, without touching the pendulum, placing a drop of adhesive simultaneously in the notches and polymerizing the adhesive.

17. A fluxgate, comprising:
a casing containing an electromagnetic assembly for detecting a magnetic field; and
a pendulum suspended from a plate of the casing by an articulation, the electromagnetic assembly being attached to the pendulum,
wherein the casing contains a liquid for damping the movements of the pendulum, and
wherein the pendulum comprises, at the opposite end from the articulation, a surface which is in the shape of a spherical cap and extends facing a wall of the casing that has a form complementary to the form of the surface, defining a space having suitable dimensions to so that the liquid for damping is subjected to laminar damping between the surface and the wall when the pendulum moves.

Assignees

• Cardoso Christian
• Habert Didier
• Merlet Etienne
• Jean Fabrice
• Magalhaes Mickael
• Pautard Sebastien
• Sagem Defense Securite

Inventors

• Cardoso Christian
• Habert Didier
• Merlet Etienne
• Jean Fabrice
• Magalhaes Mickael
• Pautard Sebastien

Classifications

• G01B7/003 Primary

  for measuring position, not involving coordinate determination (coordinate measuring G01B7/004) · CPC title

• G01R33/093

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• G01C17/30 Primary

  Earth-inductor compasses · CPC title

• G01R33/0005

  Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types (G01R33/0206 takes precedence) · CPC title

• G01R33/04

  using the flux-gate principle · CPC title