US3820499A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermally responsive cooking indicator
Assignee: 3M Co
•
Filing: 1973-03-14
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Granted: 1974-06-28
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Expires: 1993-03-14
Abstract
Abstract A body having a central bore, a plunger in the bore which plunger has a piston-like sealing member that defines a volume within the bore. A heat responsive material within such volume which expands at a predetermined temperature to move the plunger to an extended position and to afford a visual indication that the predetermined temperature has been attained. The wall of the volume defines a concavity that entraps an air bubble which avoids sudden or explosive change of state in the heat responsive material and promotes gradual movement of the plunger. The heat sensitive material can be a liquid mixture of ingredients chosen to boil at the desired temperature or can be two reactants (e.g., an acid and a base) which, at temperatures below the predetermined temperature are maintained separate from one another by a membrane that melts at the predetermined temperature. An annular cap surrounding the body for positioning the body and the heat responsive material with respect to the surface of an article of food in which the body is inserted.
Inventors
- 👤 G Kliewer
- 👤 J Roberts
- 👤 G Gee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:44
CPC Classifications
A; A47; A47J; A47J37/00; A47J37/10; G; G01; G01K; G01K1/00; G01K1/02; G01K11/00; G01K11/02; G01K5/00; G01K5/32; A47J2202/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
166 words
A thermal indicator for providing an indication of a heated condition of an article of food when the article is heated to a predetermined temperature comprising a tubular body having an opened end and a closed end, said body being configured for facilitating insertion thereof into an article of food to be heated, said body defining an axial chamber of constant cross-section in communication with said opened end, a plunger disposed in said chamber and adapted for sliding travel therein between a retracted position within said body and an extended position axially spaced from the retracted position so that the plunger extends from said opened end, said plunger having at the inner end thereof a sealing member cooperatively associated with said axial chamber for defining within said body intermediate said sealing member and said closed end an enclosed Expansible volume, and heat sensitive material experiencing substantial volumetric expansion at a temperature corresponding to said predetermined temperature so as to move the plunger to the extended position.
Claim 2
Dependent Claim
166 words
A thermal indicator for providing an indication of a heated condition of an article of food when the article is heated to a predetermined temperature comprising a tubular body having an opened end and a closed end, said body being configured for facilitating insertion thereof into an article of food to be heated, said body defining an axial chamber of constant cross-section in communication with said opened end, a plunger disposed in said chamber and adapted for sliding travel therein between a retracted position within said body and an extended position axially spaced from the retracted position so that the plunger extends from said opened end, said plunger having at the inner end thereof a sealing member cooperatively associated with said axial chamber for defining within said body intermediate said sealing member and said closed end an enclosed Expansible volume, and heat sensitive material experiencing substantial volumetric expansion at a temperature corresponding to said predetermined temperature so as to move the plunger to the extended position.
Claim 3
Dependent Claim
59 words
A thermal indicator according to claim 1 wherein said heat sensitive material includes first and second reactants disposed in said volume, a heat sensitive membrane inert to said reactants and disposed within said volume to isolate said reactants from one another, said heat sensitive membrane being adapted to fail at the predetermined temperature to afford interaction of said reactants.
Claim 4
Dependent Claim
21 words
A thermal indicator according to claim 2 wherein said first reactant is an acid and said second reactant is a base.
Claim 5
Dependent Claim
18 words
A thermal indicator according to claim 3 wherein said acid is vinegar and said base is baking soda.
Claim 6
Dependent Claim
64 words
A thermal indicator according to claim 1 wherein said plunger is approximately one-half the axial extent of said chamber so that the axial extent of said heat sensitive material is of the same order of magnitude as the distance of travel of said plunger between the retracted and extended positions and so that said heat sensitive material is remotely spaced from said opened end.
Claim 7
Dependent Claim
49 words
A thermal indicator according to claim 1 including means for positioning said body so that said opened end resides above the surface of the article of food in which the indicator resides, said positioning means including means defining a flange circumscribing and extending from the exterior of said body.
Claim 8
Dependent Claim
28 words
A thermal indicator according to claim 6 wherein said flange includes an upstanding wall at the outer periphery thereof to define an impervious cup around said opened end.
Claim 9
Dependent Claim
45 words
A thermal indicator according to claim 1 including a heat sensitive sealing plug for sealing said opened end, said plug being yieldable at or below said predetermined temperature to avoid inhibiting travel of said plunger to the extended position upon attainment of the predetermined temperature.
Claim 10
Dependent Claim
73 words
A thermal indicator according to claim 1 wherein said enclosed expansible volume is bounded in part by means defining a concavity, said concavity being formed by confronting wall portions, said wall portions being spaced from one another by an amount such that the surface tension of the heat resistive material supports the material in spanning relation with respect to the wall portions so as to entrap a quantity of air in said concavity.
Claim 11
Dependent Claim
21 words
A thermal indicator according to claim 9 wherein said concavity defining means is disposed at one axial extremity of said volume.
Claim 12
Dependent Claim
22 words
A thermal indicator according to claim 10 wherein said concavity defining means is disposed in said tubular body at said closed end.
Claim 13
Dependent Claim
21 words
A thermal indicator according to claim 10 wherein said concavity defining means is disposed in the sealing member of said plunger.
Claim 14
Dependent Claim
49 words
A thermal indicator according to claim 12 wherein said closed end of said body is formed by an opening and a plug sealable in said opening so that during assembly of the indicator said heat sensitive material can be introduced through said opening prior to installation of said plug.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |