Acceleration-responsive apparatus for sensing firing instant of an air gun

A variable reluctance-type firing sensor adapted to be mechanically coupled to an air gun for providing an electrical signal indicative of the instant of firing of the air gun comprising:

• a magnetic circuit having a permanent magnet therein,
• said magnetic circuit including two spaced portions,
• an axially movable armature member including magnetically permeable material in said magnetic circuit, said movable armature member normally being held by magnetic action in predetermined axial position with respect to said two spaced portions of the magnetic circuit,
• said movable armature member being acceleration-responsive for moving in an axial direction away from said predetermined position with respect to said two spaced portions for changing the reluctance in said magnetic circuit upon the firing of the air gun,
• a coil coupled with said magnetic circuit for generating an electrical signal when said armature member moves with respect to said two spaced portions of said magnetic circuit,
• an insulating layer on the outside of one of said spaced portions,
• a pair of separated conductive areas on said insulating layer,
• said insulating layer and said one portion having aligned openings therethrough, with said opening through said portion being larger than said opening through said insulating layer,
• the ends of said coil extending through said openings and being connected to said separated conductive areas, thereby providing electrical terminal contact means for said coil, and
• said firing sensor being mounted in a cable connector and being connected to wires in the cable, said cable connector being adapted to be secured onto a solenoid valve of an air gun,
• thereby indicating the instant of firing of said air gun.

A variable reluctance-type firing sensor adapted to be mechanically coupled to an air gun for providing an electrical signal indicative of the instant of firing of the air gun comprising:

• a magnetic circuit having a permanent magnet therein,
• said magnetic circuit including two spaced portions,
• an axially movable armature member including magnetically permeable material in said magnetic circuit,
• said movable armature member normally being held by magnetic action in predetermined axial position with respect to said two spaced portions of the magnetic circuit,
• said two spaced portions being formed by two pole pieces of magnetically permeable material,
• said two pole pieces having aligned holes therein,
• said movable armature member being normally magnetically suspended in rest position symmetrically positioned in spanning relationship between said two pole pieces,
• the ends of said movable armature member being partially inserted equal amounts into each of said two holes when said armature is in rest position,
• said movable armature being acceleration-responsive for moving in an axial direction away from said rest position with respect to said two spaced pole pieces for changing the reluctance in said magnetic circuit upon the firing of the air gun, and
• a coil coupled with said magnetic circuit for generating an electrical signal when said armature member moves with respect to said two spaced pole pieces,
• thereby indicating the instant of firing of said air gun.

A variable reluctance-type sensor adapted to indicate a sudden acceleration in a predetermined direction comprising:

• a magnetic circuit having a permanent magnet therein,
• said magnetic circuit including two spaced pole pieces of magnetically permeable material,
• said pole pieces each having a hole therein,
• said spaced pole pieces being mounted with said holes in aligned position,
• an elongated armature containing magnetically permeable material and normally being in rest position with its respective ends partially inserted into the respective holes in said pole pieces,
• said armature being axially movable with respect to said pole pieces and normally being suspended in said rest position solely by magnetic action with each end of the armature being partially inserted into one of said holes,
• said sensor being adapted to be mounted with the length of said elongated armature extending in said predetermined direction in which said acceleration occurs, and
• a coil coupled to said magnetic circuit for providing an electrical signal when the ends of said armature are suddenly displaced from said normal rest position with respect to said holes in said pole pieces as caused by sudden acceleration of said sensor in said direction.