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US 5,473,941 AGranted
Encapsulated accelerometer with faraday shielding
AssigneeVibra-Metric, Inc.
InventorsJohn E. Judd, Yi H. Lo
Life of this patent
Estimating the term…
Abstract
An accelerometer with internal electronics is mounted within a Faraday shield and encapsulated within a non-electrically conductive material applied by hot injection molding at a high pressure to form a hermetically sealed case with integral strain-relief, cable bend protection, ground loop isolation and protection against EMI/RFI interference through both conduction and radiation. The accelerometer is shaped as a torus with the center hole providing center hole bolt mounting.
Claims15
An accelerometer comprising:
- a sensor sensitive to accelerations;
- an electrical circuit having an input connected to the sensor and a low impedance output;
- a cable connected to the output of the electrical circuit;
- a toroidally shaped housing adapted for mounting to a mounting surface by means of a bolt passing through the toroidally shaped housing comprising:
- a shield formed of an electrically conductive material, the shield extending substantially completely around the sensor and the circuit to prevent electromagnetic and radio frequency interference;
- and
- an encapsulant formed of an electrically nonconductive material, the encapsulant forming the exterior of the housing and extending substantially completely around the shield, the encapsulant hermetically sealing the housing to the cable to provide strain relief between the cable and the housing at a point exterior of the shield and electrically isolating the shield and the accelerometer from the mounting surface.
4 more elements
An accelerometer comprising:
- a piezoelectric sensor;
- an electrical circuit including an amplifier with an input connected to the sensor and a low impedance output;
- a Faraday shield extending substantially completely around the piezoelectric sensor and the electrical circuit;
- and
- a cable including at least one wire and an insulating coating surrounding the wire, the wire extending through the Faraday shield and being connected to the output of the electrical circuit;
- the Faraday shield being substantially completely encapsulated within an electrically nonconductive material applied by hot injection molding at a pressure of at least 1000 pounds per square inch, the encapsulating material contacting the insulating coating surrounding the wire and forming a hermetic seal therewith around the Faraday shield.
3 more elements
An accelerometer comprising:
- a two element piezoelectric sensor mounted for shear mode sensing;
- an electrical circuit including an amplifier connected to the two elements of the piezoelectric sensor and having a low impedance output, the electrical circuit being reverse voltage protected and temperature equalized;
- a Faraday shield with an insulated opening forming a wire entrance through the shield, the Faraday shield extending substantially completely around the piezoelectric sensor and the electrical circuit and shaped as a torus having a central opening;
- a coaxial cable including:
- a center conductor extending through the insulated opening in the Faraday shield, connected to the output of the electrical circuit,
- a shield conductor connected to the Faraday shield;
- an insulating coating surrounding the coaxial cable, and
- a connector at a terminal end of the coaxial cable;
- a cable sleeve connected to the coaxial cable including protruding elements forming a mechanical connection means;
- and
- an encapsulant substantially completely encapsulating the Faraday shield within an electrically nonconductive, impact resistant, industrial chemical resistant encapsulating material, the encapsulating material being applied by hot injection molding to hermetically seal the Faraday shield, the insulated opening and the coaxial cable;
- the encapsulating material engaging the protruding elements of the cable sleeve to provide strain relief for the coaxial cable.
9 more elements
Dependencies are inferred from the claim text.