×

Linear accelerometer with improved magnetic rebalance system

  • US 4,145,929 A
  • Filed: 09/21/1977
  • Issued: 03/27/1979
  • Est. Priority Date: 09/21/1977
  • Status: Expired due to Term
First Claim
Patent Images

1. In acceleration responsive apparatus of the type including magnet means for producing a magnetic field in which is located a coil forming at least a portion of a sensing mass suspended for movement along an input axis fixed relative to the magnet means, a servo system for supplying current to the coil to maintain the sensing mass in a predetermined position along the input axis and pickoff means for supplying a signal indicative of displacement of the sensing mass from the predetermined position, improved force rebalance means for minimizing errors resulting from current in the coil, comprising:

  • a permanent magnet aligned with the input axis;

    a magnetically permeable sleeve concentric with said permanent magnet and substantially coextensive therewith along the input axis, said permanent magnet and said sleeve cooperating to define a first annular gap containing a substantially radial inwardly directed magnetic field and a second annular gap containing a substantially radial outwardly directed magnetic field;

    a tubular bobbin carrying first and second circumferential coils wound in opposite directions and connected in series;

    first and second torsion hinge means respectively located along first and second parallel hinge axes perpendicular to the input axis on opposite sides thereof, said first torsion hinge means being fixed relative to said permanent magnet and said second torsion hinge means being fixed relative to said tubular bobbin;

    first intermediate arm means joining said first and second torsion hinge means;

    third and fourth torsion hinge means respectively located along third and fourth parallel hinge axes on opposite sides of the input axis and parallel with the first and second hinge axes, said third torsion hinge means being fixed relative to said permanent magnet means and said fourth torsion hinge means being fixed relative to said tubular bobbin;

    second intermediate arm means joining said third and fourth torsion hinge means, whereby said tubular bobbin is constrained from movement transverse to the input axis;

    a servo system for producing a positioning current; and

    conductor means, including said first and second torsion hinge means and said first intermediate arm means, for carrying the positioning current to the first and second coils, the positioning current having no net effect on the magnetic flux in the first and second gaps because of the oppositely directed magnetic fluxes produced by current in the first and second coils.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×