Hot-wire anemometer gyro pickoff

• US 4,361,054 A
• Filed: 12/05/1980
• Issued: 11/30/1982
• Est. Priority Date: 12/05/1980
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Bailey, Escar L.
• Primary Examiner(s): Bonck, Rodney H.
• Application Number:
  US06/213,522
• Time in Patent Office: 725 Days
• Field of Search: 74/5.6 D, 74/5.6 R, 74/5.6 B, 73/505, 33/363 Q, 33/317 R
• US Class Current: 74/5.60D
• CPC Class Codes: G01C 19/28 Pick-offs, i.e. devices for taking-off an indication of the displacement of the rotor axis
• CPC Class Codes: Y10T 74/1261 with pick off
• CPC Class Codes: Y10T 74/1275 Electrical

Abstract

An arrangement of hot-wire anemometers is set partially into the rotor boary layer so that they form two resistors of a wheatstone bridge circuit for each axis. The hot wire resistors change in resistance according to the angular offset from null of the gyro rotor. The combination of resistance changes is then used in the bridge circuit to provide an electrical signal which is directly proportional to gyro rotor angular offset.

Claims

1. In a system for measuring movement of a rotating means which has a boundary layer of flowing fluid about its rotating surface, the improvement comprising a nonlinear resistor having a length which is long in comparision to its diameter;

circuit means connected to said resistor so as to cause current flow through said resistor and to cause said resistor to increase in temperature;

said resistor being placed relative to said rotating means such that only a portion of said resistor will be in said boundary layer;

when said rotating means moves relatively to said resistor, a different proportion of said resistor will be within said boundary layer;

said nonlinear resistor being such that the more of the resistor that is located within the boundary layer, the more the resistor is cooled; and

measurement means connected to said resistor to sense the amount of cooling of the resistor, and therefore, the amount of motion of said rotating means relative to said resistor.

2. A system as set forth in claim 1 wherein said nonlineary resistor is nonlinear in respect to temperature.

3. A system as set forth in claim 2 wherein said rotating means is a gyro rotor and said resistor being located to sense moving of one axis of said gyro rotor.

4. A system as set forth in claim 1 or 3 further providing a second nonlinear resistor located relative to the original resistor such that when the rotor moves relative to said original resistor to change the amount of the length of the resistor is within the boundary layer, the second resistor will have the amount of its length within the boundary layer changed in the opposite amount of the original resistor;

and measurement means connected to both resistors so as to sense the electrical difference between the resistors.

5. A system as set forth in claim 4 wherein each nonlinear resistor take the form of a short length of fine platinum wire.

6. A system as set forth in claim 5 wherein said measurement means is a wheatstone-bridge having the two nonlinear resistors as two adjacent legs in the bridge network.