REMOTE MONITOR AND INDICATING SYSTEM

• US 3,739,376 A
• Filed: 10/12/1970
• Issued: 06/12/1973
• Est. Priority Date: 10/12/1970
• Status: Expired due to Term

• Current Assignee: Francis C. Keledy
• Original Assignee: Francis C. Keledy
• Inventors: Keledy, Francis C.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/079,797
• Time in Patent Office: 974 Days
• Field of Search: 340/224,258R,258C,58,152T,282,267R,271,27R,421,195,416 343/18R,18A,6.5SS 244/17.11 250/231R
• US Class Current: 340/946
• CPC Class Codes: B64C 27/007 adapted for detection of blade cracks
• CPC Class Codes: G08B 25/00 Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
• CPC Class Codes: G08C 19/12 in which the signal transmitted is frequency or phase of ac

Abstract

A passive parameter-sensing element is disposed at a location remote from an indicator. Upon the occurrence of a predetermined variation in the sensed parameter, an active unit coupled to the passive element produces a signal which operates the indicator. In one embodiment of the invention a plurality of passive sensing elements are housed in the blades of a helicopter. Upon the sensing of a change in the air pressure in one of the blades, the response of the passive element in that blade causes the active unit to produce a signal which has a characteristic uniquely associated with the particular blade in which the failure occurs.

Claims

1. A system for monitoring a parameter at a plurality of spaced locations, said system comprising a plurality of parameter responsive switching means respectively located at said locations and operable in response to a predetermined change of said parameter, a plurality of electrically passive, normally inoperative resonant circuits respectively coupled to said parameter-sensitive means, said parameter sensitive switching means being effective when operated to render operative a corresponding one of said resonant circuits, a plurality of electrically active sources of signals at different frequencies located remote from said passive resonant circuits, a single winding coupled to the outputs of said plurality of signal sources and inductively coupled to said plurality of passive resonant circuits and effective upon the operation of one of said parameter-sensitive switching means to produce an electrical signal at one of said frequencies, said one of said frequencies being uniquely associated with said one of said parametersensitive means, a corresponding plurality of indicating means located remote from said passive resonant circuits, and a corresponding plurality of means having an input coupled to said single winding and an output respectively coupled to said indicating means for selectively applying said unique frequencies signal to a corresponding one of said plurality of indicating means.

2. The system of claim 1, in which said passive resonanT circuits each comprise an inductive winding inductively coupled to said single winding.

3. The system of claim 2, in which each of said signal sources includes a tuned circuit, said transformer winding being a component of the tuned circuit of each of said signal sources.

4. The system of claim 1, in which said signal applying means includes frequency-sensitive means respectively operatively interposed between said signal sources and said plurality of indicating means.

5. The system of claim 4, in which the outputs of each of said signal sources are coupled to a common point, and the inputs of said frequency-sensitive means are all coupled to said common point.

6. The system of claim 4, in which each of said indicating means comprises a first element operative only when the corresponding one of said parameter-sensitive means is in an operative condition, and a second element operative only when the corresponding one of said parameter-sensitive means is in its inoperative condition.

7. The system of claim 6, further comprising means operatively interposed between said signal producing means and said indicating means for selectively applying a control signal to one of said indicator elements in response to the condition of the associated one of said parameter-sensitive means.

8. In an aircraft having a plurality of blades rotatably mounted on a rotor, means on said aircraft for directing a beam of electromagnetic energy along a direction offset from the axis of the rotor so that when said blades are rotated said beam is sequentially and periodically interrupted by said blades, passive energy reflective means carried by said blades, switching means carried by said blades and operable in response to a change in the internal pressure of one of said blades for altering the reflective characteristics of the passive reflecting means on said one of said blades, and means located in the cockpit of said aircraft for sensing the change in the reflective characteristics of said passive reflective means, to thereby provide a warning indication.

9. The apparatus of claim 8, in which said passive reflective means each provide a different reflected signal to said sensing means, and further comprising means coupled to said sensing means for distinguishing the reflected signal, and a plurality of indicating means coupled to said signal-distinguishing means, one of said indicating means being made operative upon the operation of a corresponding one of said switch means.

10. A system for detecting and indicating a predetermined change in a specified parameter at a plurality of remote locations comprising a plurality of electrically passive, normally inoperative resonant circuits resonant at a different frequency when operative and located respectively at said remote locations, a plurality of parameter-sensing switch means respectively coupled to said resonant circuits, said switch means being normally in a first inoperative state and being placed in a second operative state in response to said predetermined change in said parameter at one of said remote locations to render the one of said resonant circuits at said one remote location operative, a plurality of electrically active transmitting means producing signals at different frequencies and spaced from said remote locations and from said passive resonant circuits, said different frequencies being respectively approximately equal to the resonant frequencies of said resonant circuits, means for respectively inductively coupling said transmitting means to said passive resonant circuits, means coupled to said passive resonant circuits through said inductive coupling means for producing a fault signal upon the operation of said one of said passive resonant circuits, and indicating means coupled to said fault signal producing means and operable in response to said fault signal for providing an indication whenever said parameter changes by at least said predetermined amount at said one remote location.

11. The system of claim 10, in which said indicating means comprises a corresponding plurality of indicators, and further comprising a corresponding plurality of frequency-sensitive means respectively operatively interposed between said transmitters and said plurality of indicators.