THERMAL CHANGE DETECTOR OF THE LINEAR THERMOPILE TYPE

• US 3,644,913 A
• Filed: 12/16/1969
• Issued: 02/22/1972
• Est. Priority Date: 12/16/1969
• Status: Expired due to Term

• Current Assignee: Masatoshi Matsui
• Original Assignee: Masatoshi Matsui
• Inventors: Matsui, Masatoshi
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Wannisky, William M.
• Application Number:
  US04/885,505
• Time in Patent Office: 798 Days
• Field of Search: 340/228,227 136/208,211,212,223,224,227,216
• US Class Current: 340/588
• CPC Class Codes: G01K 3/10 in respect of time, e.g. reacting only to a quick change of temperature
• CPC Class Codes: G08B 17/06 Electric actuation of the alarm, e.g. using a thermally-operated switch

Abstract

An improved thermal change detector of the linear thermopile type is disclosed. A transient temperature differential between adjacent thermopile junctions is obtained by shaping each link in the linear thermopile asymmetrically and joining them so that the thermal capacity of the '"'"''"'"''"'"''"'"'hot'"'"''"'"''"'"''"'"' junctions is smaller than that of the '"'"''"'"''"'"''"'"'cool'"'"''"'"''"'"''"'"' junctions. When a rapid rise occurs in the temperature of the environment, as for example when a fire breaks out, the '"'"''"'"''"'"''"'"'hot'"'"''"'"''"'"''"'"' junctions, having less thermal capacity, heat up more quickly than the '"'"''"'"''"'"''"'"'cool'"'"''"'"''"'"''"'"' junctions. This produces an electric potential across the thermopile which may be used to trigger alarm circuitry.

Claims

1. A thermal change detector comprising a plurality of first links of a material chosen from the group consisting of metals and metal alloys, an equal number of second links of a different material chosen from said group, the first and second links being of equal dimensions and having equal portions of material removed from one end thereof to provide the one end with a smaller thermal capacity than the other end, the first and second links being arranged in alternate sequence with the smaller thermal capacity ends joined together, means for completing an electrical circuit connecting the first and last link in the sequence, the materials of the first and second links being chosen so that when the detector is subjected to a thermal change a net voltage other than zero appears across the links.

2. A thermal change detector as described in claim 1 wherein the linear arrangement of the links is covered by a protective coating.

3. A thermal change detector as claimed in claim 1 wherein the links are linearly arranged in alternating sequence.

4. A thermal change detector as claimed in claim 1 wherein the links are shaped to have one solid end and one tubular end.

5. A thermal change detector as claimed in claim 1 wherein the first links are made of iron and the second links of constantan.

6. A thermal change detection system comprising a plurality of spaced thermopiles wherein each of the thermopiles comprises a number of first links of a material chosen from the group consisting of metals and metal alloys, the same number of second links of a different material chosen from the same group, the first and second links being of equal dimensions and having equal portions of material removed from one end thereof to provide the one end with a smaller thermal capacity than the other end, the first and second links being linearly arranged in alternating sequence with the smaller thermal capacity ends joined, the materials of the first and second links being chosen so that when the thermopile is subjected to a thermal change a net nonzero voltage appears across the thermopile, the spaced thermopiles being interconnected in series By circuit-completing means.

7. A thermal change detection system as described in claim 6 wherein the circuit-completing means includes alarm means.

8. A thermal change detection system as described in claim 6 wherein each thermopile is covered by a protective coating.

9. A thermal change detection system as described in claim 6 wherein the one end of each link having a smaller thermal capacity is tubular and the other end of each link having a larger thermal capacity is solid.

10. A thermal change detection system as described in claim 9 wherein the circuit-completing means includes alarm means.