Temperature monitoring system

• US 5,446,452 A
• Filed: 02/05/1993
• Issued: 08/29/1995
• Est. Priority Date: 02/05/1993
• Status: Expired due to Term

• Current Assignee: Vee Reeder
• Original Assignee: Reeder-Tronics Corporation
• Inventors: Litton, Charles J.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Burgess, Glenton B.
• Application Number:
  US08/014,178
• Time in Patent Office: 935 Days
• Field of Search: 340/870.17, 340/682, 340/870.16, 340/445, 340/447, 340/825.54, 340/600, 340/584, 246/169, 73/292, 128/736
• US Class Current: 340/870.17
• CPC Class Codes: B61K 9/04 Detectors for indicating the overheating of axle bearings and the like, e.g. associated with the brake system for applying the brakes in case of a fault
• CPC Class Codes: F16C 19/525 related to temperature and heat, e.g. insulation
• CPC Class Codes: F16C 41/008 Identification means, e.g. markings, RFID-tags; Data transfer means
• CPC Class Codes: G01K 1/024 for remote indication

Abstract

A temperature measuring system is described which is activated in response to the occurrence of detecting a temperature greater than a predefined critical temperature which includes a transceiver which receives an incoming electromagnetic wave, a temperature sensing means, e.g. a gas thermometer to measure the temperature of the desired component, and an electromagnetically interrogatable transponder chip capable of selectively transitioning from an inactive state to an active state upon the temperature exceeding the predefined critical temperature. The transponder chip when in the active state, converts the electromagnetic wave to a surface acoustic wave which passes over the transponder chip and upon exiting from the transponder chip is reconverted to an electromagnetic wave which is slightly modified from the incoming electromagnetic wave. The difference between the incoming and outgoing electromagnetic wave being a modulated signal which contains information which has been encoded on the transponder for retransmission by the transceiver. The invention also describes a process for detecting a hot component which utilizes the steps of determining the temperature of a component, e.g. a bearing, comparing the component temperature to a predefined critical temperature, upon detecting that the component temperature has exceeded the critical temperature, then closing the transponder chip circuit thereby allowing an incoming electromagnetic wave by the transponder chip to be received and converted to a surface acoustic wave as it passes the path of the transponder chip receiving information encoded in the chip for subsequent conversion to a modulated electromagnetic wave and retransmitting the modulated electromagnetic wave to a decoder for identification of the overheated component.

Claims

1. A temperature monitoring system activated in response to the occurrence of detecting a temperature greater than a predefined critical temperature which comprises:

(a) a transceiver which receives an incoming electromagnetic wave and subsequently retransmits a modified electromagnetic wave;

(b) a temperature sensing means which upon detecting the temperature which is greater than the predefined critical temperature will complete an electronic circuit which is initially in an open inactive state; and

(c) an electromagnetically interrogatable transponder chip capable of selectively transitioning from the inactive state to an active state upon the temperature sensing means detecting the predefined critical temperature, the transponder chip when in the active state, converts the electromagnetic wave to a surface acoustic wave which passes over the transponder chip and upon exiting from the transponder chip is reconverted to an electromagnetic wave which is slightly modified from the incoming electromagnetic wave, the modification being a modulated signal which contains information which has been encoded on the transponder for retransmission by the transceiver.

2. The system of claim 1 wherein the temperature sensing means is a gas thermometer.

3. The system of claim 1 wherein the selective transitioning from the inactive to the active state is automatic upon the sensing means detecting the critical temperature.

4. The system of claim 3 wherein the selective transitioning is effected by a piston activated by a pressure generated by the gas in a temperature sensing means.

5. The system of claim 1 wherein the transponder comprises:

(a) an IDT; and

(b) a LiNbO₃.

6. A temperature monitoring system activated in response to the occurrence of detecting a temperature greater than a predefined critical temperature which comprises:

(a) an interrogatable tag containing specific identification coding of a piece of equipment, the tag being capable of receiving an unmodulated electromagnetic wave and modulating it with encoded information for subsequent retransmission by frequency shift keying as a retransmitted modulated electromagnetic wave;

(b) an RF module which generates oscillating electromagnetic radiation used to query, the tag and receive the retransmitted modulated electromagnetic wave; and

(c) a reader to decode the retransmitted modulated electromagnetic wave.

7. The system of claim 6 wherein the interrogatable tag comprises:

(a) a transceiver to receive the unmodulated electromagnetic wave and retransmit the modulated electromagnetic wave;

(b) a code generator to convert equipment-specific information into computer data;

(c) a real-time computer clock to sequence all circuit functions so that encoded information is conveyed to the reader within precise timing;

(d) a non-volatile memory containing the equipment-specific information; and

(e) a modulator to collect the computer data from the non-volatile memory and retransmit the data through the transceiver to a reader system.

8. The system of claim 6 wherein the system further comprises a power source.

9. The system of claim 8 wherein the power source is a battery.

10. The system of claim 6 wherein the RF module comprises:

(a) an RF oscillator to generate a continuous unmodulated electromagnetic wave;

(b) an RF processor to amplify the wave;

(c) a transceiver to transmit the wave and receive a modulated electromagnetic wave containing equipment specific information reflected from a tag; and

(d) a receiver to separate the continuous unmodulated electromagnetic wave from the modulated electromagnetic wave containing the equipment specific information.

11. The reader of claim 6 which further comprises a decoder which translates the modulated frequencies using a modified frequency shift keying code using two harmonically-related frequencies into a binary information equivalent of the modulated frequency transmitted from the RF module.

12. A process for detecting a hot component which comprises the steps of:

(a) determining a temperature of a component;

(b) comparing the temperature to a critical temperature;

(c) repeat steps (a) and (b) until the temperature is at least equal to a critical temperature;

(d) close a circuit in a transponder chip when the temperature is at least equal to the critical temperature;

(e) receive an incoming electromagnetic wave by the transponder chip which is converted to a surface acoustic wave, which passes over a path of the transponder chip receiving information encoded in the chip;

(f) converting the surface acoustic wave to a modulated electromagnetic wave; and

(g) retransmitting the modulated electromagnetic wave to a decoder for identification of the component.