Vertical card magnetic compass

• US 3,875,676 A
• Filed: 12/12/1973
• Issued: 04/08/1975
• Est. Priority Date: 09/27/1971
• Status: Expired due to Term

• Current Assignee: Phelps M. Lane
• Original Assignee: Leslie A. Hamilton
• Inventors: Hamilton, Leslie A.
• Primary Examiner(s): Aegerter, Richard E.
• Assistant Examiner(s): Stearns, Richard R.
• Application Number:
  US05/424,000
• Time in Patent Office: 482 Days
• Field of Search: 33/355R,355A,345
• US Class Current: 33/345
• CPC Class Codes: G01C 17/20 Observing the compass card or needle

Abstract

The present invention relates to a dry magnetic compass having a self-contained, vertically oriented card specially suited, for example, for mounting on an airplane instrument panel. Because of the vertical display, the entire compass card can be seen in the correct position relative to the line of flight. The device includes a non-ferrous housing having a transparent face, a compass card in the vertical plane within the housing fully viewable through the transparent face, the compass card being journalled in the housing to rotate about a central axis perpendicular to the card, a magnet means journalled for rotation about a vertical axis within the housing, and gearing for translating rotative movement of the magnet means to the compass card. Rather than conventional fluid damping, the compass of the present invention is damped by utilization of eddy current effect.

Claims

1. A dry magnetic compass for use in an aircraft comprising, a. a non-ferrous housing, b. a transparent, vertically oriented plate secured to and forming one wall of the housing (a) and having a lubber line in the outline of an aircraft thereon, c. a nonferrous support member adapted to be secured within the housing (a), d. a vertically oriented, circular compass card spaced adjacent the transparent plate (b) and indicating true compass positions thereon and having a central shaft secured to the card perpendicular to and rearward of the face thereof, the shaft being journalled to the support member (c) and having a bevel gear secured threon, e. a circular magnet to which is secured a downwardly extending vertical shaft that is rotatably journalled in the support member (c), the circular magnet having a bevel gear secured to the upper portion thereof to meshingly engage the bevel gear of the compass card, and f. means for eddy current damping of movement of the magnet (e).

2. The invention of claim 1 wherein, more specifically, the eddy current damping means (f) comprises a non-ferrous conductor spaced adjacent to the circular magnet (e) such that an air gap is provided therebetween.

3. The invention of claim 2 wherein the non-ferrous conductor is a shield formed of a non-magnetic metal.