US4281309A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermally actuated cut-off link or switch and method of making the same
Assignee: Littelfuse Inc
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Filing: 1979-04-02
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Granted: 1981-07-28
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Expires: 1999-04-02
Abstract
Abstract An ambient thermally actuated switch comprises a power lead extending longitudinally into and insulated from one end of a metal casing. The power lead made of a soft low resistance material like copper is bifurcated at its inner end to form outwardly inclining arms which, in a normally closed embodiment of the switch, makes contact with the inner surface of the casing. The arms are pressed against an insulating backing member so that the arms expand outwardly into a low resistance contact with the casing. The backing member forms part of a spring-urged, longitudinally extending, sandwich of elements extending between the ends of the casing and preferably comprising a pellet of meltable material, a first partially compressed spring, said backing member, arm-deforming means positioned contiguous to and adapted to collapse said arms when released to do so, and a second fully compressed spring applying a force acting on said deforming means to force it into an arm-collapsing position when the pellet melts. In assembling the switch, the bifurcated power lead is pushed against the backing member with a force which provides a desired measure low resistance and the power lead is anchored in this adjusted position.
Inventors
- 👤 Harry W. Olson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:04
CPC Classifications
H; H01; H01H; H01H37/00; H01H37/74; H01H37/76; H01H37/764; H01H37/765; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49107
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
208 words
An ambient thermal switch comprising: a casing of electrically conductive material; a first power lead in said casing exposed to the outside of said casing through an opening in said casing where it is insulated therefrom, said first power lead having at the inner end thereof deformable contact-forming arm means for making a low resistance contact with the inner conductive surface of said casing when expanded outwardly to a given degree; a second exposed power lead making a permanent low resistance connection with said casing; a sandwich of serially located elements urged under spring pressure between fixed spaced points in said casing and including stressed spring means, arm-deforming means for deforming said arm means inwardly out of contact with said casing, backing means for said arm means for expanding said arm means against said casing to establish a given low resistance contact therewith, and a fusible body which melts at a given control temperature causing the stressed spring means to move to an unstressed state, said spring, arm-deforming and backing means being positioned for causing one of said arm-deforming and backing means to move against said arm means when the spring means moves to its unstressed state and effecting the expanding or contracting of said contact-forming arm means.
Claim 2
Dependent Claim
208 words
An ambient thermal switch comprising: a casing of electrically conductive material; a first power lead in said casing exposed to the outside of said casing through an opening in said casing where it is insulated therefrom, said first power lead having at the inner end thereof deformable contact-forming arm means for making a low resistance contact with the inner conductive surface of said casing when expanded outwardly to a given degree; a second exposed power lead making a permanent low resistance connection with said casing; a sandwich of serially located elements urged under spring pressure between fixed spaced points in said casing and including stressed spring means, arm-deforming means for deforming said arm means inwardly out of contact with said casing, backing means for said arm means for expanding said arm means against said casing to establish a given low resistance contact therewith, and a fusible body which melts at a given control temperature causing the stressed spring means to move to an unstressed state, said spring, arm-deforming and backing means being positioned for causing one of said arm-deforming and backing means to move against said arm means when the spring means moves to its unstressed state and effecting the expanding or contracting of said contact-forming arm means.
Claim 3
Dependent Claim
41 words
The ambient thermal switch of claim 1 wherein said contact-forming arm means forms an integral part of said first power lead so that the interface between said arm means and casing is the only separable contact interface between said power leads.
Claim 4
Dependent Claim
51 words
The ambient thermal switch of claim 1 or 2 wherein said casing has a curved inner conductive surface contacted by said arm means, and said arm means is made of a relatively soft highly conductive material which when pressed against said casing deforms to engage the switch over a greater area.
Claim 5
Dependent Claim
53 words
The ambient thermal switch of claim 1 wherein said arm-deforming means is a body of insulating material having a cavity therein, and said contact-forming arm means when deformed by said arm-deforming means being fully retracted into said cavity so that the body of insulating material fully insulates the arm means from the casing.
Claim 6
Dependent Claim
57 words
The ambient thermal switch of any of the preceding claim 1 wherein said fusible body is a body of fusible granular material compressed into said closed end of the casing so it expands and closely engages the exposed inner surfaces of the casing, to enable external heat to readily pass into said compressed body of fusible material.
Claim 7
Dependent Claim
336 words
An ambient thermal actuated cut-off link comprising: a casing of electrically conductive material; a first power lead in said casing exposed to the outside of said casing through an opening in said casing where it is insulated therefrom, said first power lead having at the inner end thereof laterally outwardly extending, inwardly deformable contact-forming arm means making a low resistance contact with the inner conductive surface of said casing; a second exposed power lead making a permanent low resistance contact with the inner conductive surface of said casing; a second exposed power lead making a permanent low resistance connection with said casing; a sandwich of serially located elements urged under spring pressure between fixed spaced points in said casing and comprising first fully compressed spring means, arm-deforming means on one side of said arm means and urged by said fully compressed spring means toward said arm means to deform the same inwardly when the fully compressed spring means is allowed to expand, backing mean on the other side of said arm means and against which said arm means bear and are expanded against said casing to establish a given low resistance contact therewith, second compressed spring means for keeping said first spring means fully compressed and for taking up any play in said sandwich of elements, and a fusible body which melts at a given control temperature, said backing means being located between said fully compressed spring means and second spring means so that the position of said backing means is fixed within said sandwich of elements as long as said fully compressed means remains full compressed, whereby the contact resistance between said arm means and casing does not vary with the degree of compression of said second spring means, the melting of said body of meltable material at said control temperature first causing said second spring means to expand, after which said fully compressed spring means expand to force said arm deforming means against said contact-forming arm means to disengage the same from said casing.
Claim 8
Dependent Claim
336 words
An ambient thermal actuated cut-off link comprising: a casing of electrically conductive material; a first power lead in said casing exposed to the outside of said casing through an opening in said casing where it is insulated therefrom, said first power lead having at the inner end thereof laterally outwardly extending, inwardly deformable contact-forming arm means making a low resistance contact with the inner conductive surface of said casing; a second exposed power lead making a permanent low resistance contact with the inner conductive surface of said casing; a second exposed power lead making a permanent low resistance connection with said casing; a sandwich of serially located elements urged under spring pressure between fixed spaced points in said casing and comprising first fully compressed spring means, arm-deforming means on one side of said arm means and urged by said fully compressed spring means toward said arm means to deform the same inwardly when the fully compressed spring means is allowed to expand, backing mean on the other side of said arm means and against which said arm means bear and are expanded against said casing to establish a given low resistance contact therewith, second compressed spring means for keeping said first spring means fully compressed and for taking up any play in said sandwich of elements, and a fusible body which melts at a given control temperature, said backing means being located between said fully compressed spring means and second spring means so that the position of said backing means is fixed within said sandwich of elements as long as said fully compressed means remains full compressed, whereby the contact resistance between said arm means and casing does not vary with the degree of compression of said second spring means, the melting of said body of meltable material at said control temperature first causing said second spring means to expand, after which said fully compressed spring means expand to force said arm deforming means against said contact-forming arm means to disengage the same from said casing.
Claim 9
Dependent Claim
41 words
The ambient thermal cut-off link of claim 6 wherein said arm means forms an integral part of said first power lead so that the interface between said arm means and causing is the only separable contact interface between said power leads.
Claim 10
Dependent Claim
59 words
The ambient thermal cut-off link of claim 6 wherein said solid body of meltable material is spaced from said fully compressed spring means and arm-deforming means, and said arm-deforming means is positioned immediately contiguous to said arm means, so that initiation of outward expansion of said fully compressed spring means will cause immediate inward deformation of said arm means.
Claim 11
Dependent Claim
51 words
The ambient thermal cut-off link of claim 6 wherein said casing has a curved inner conductive surface contacted by said arm means, and said arm means is made of a relatively soft highly conductive material which when pressed against said casing it forms to engage the same over a greater area.
Claim 12
Dependent Claim
48 words
The ambient thermal cut-off link of claim 8 or 9 wherein said arm means are integral with said first power lead, so that no separable contact-interface is formed therewith, the interface between said arm means and casing thus being the only separable contact interface between said power leads.
Claim 13
Dependent Claim
45 words
The ambient thermal cut-off link of claim 6 wherein said sandwich elements comprises, in the order named, said first fully compressed spring means, arm-deforming means positioned immediately between said fully compressed spring means and said arm means, backing means, second spring means, and fusible body.
Claim 14
Dependent Claim
26 words
The ambient thermal cut-off link of claim 6 wherein said arm means extends laterally outwardly into engagement with said casing through apertures in said arm-deforming means.
Claim 15
Dependent Claim
23 words
The ambient thermal cut-off link of claim 11 wherein said second spring means is located between said fusible body and said backing means.
Claim 16
Dependent Claim
36 words
The ambient thermal cut-off link of claim 13 wherein said sandwich of elements include a first pressure-distributing disc between said second spring means and said fusible body, and said second spring means being a coil spring.
Claim 17
Dependent Claim
24 words
The ambient thermal cut-off link of claim 14 wherein a coil of said second spring means engages the pressure-distributing disc at the perimeter thereof.
Claim 18
Dependent Claim
54 words
The ambient thermal cut-off link of claim 6 wherein said fully compressed spring means and said second spring means are both solid bodies of compressible resilient material spaced apart on opposite sides of said deformable contact-forming arm means, said spring means under compression being expanded to form a hermetic seal with said casing walls.
Claim 19
Dependent Claim
39 words
The cut-off link of claim 16 wherein said first power lead passes through said fully compressed spring means which is expanded inwardly by the force from said second spring means into hermetic sealing relationship with said first power lead.
Claim 20
Dependent Claim
377 words
An ambient thermal cut-off link comprising: a casing of electrically conductive material having inner conductive surfaces; a first power lead extending longitudinally into one end of said casing at a point where it is insulated therefrom, said first power lead terminating within said casing in laterally outwardly extending, inwardly deformable contact-forming arm means making a low resistance contact with said curved inner conductive surface of said casing and which are integral with said first power lead so that no separable contact interface is formed therewith; a second power lead extending longitudinally into the other end of said casing and making a permanent low resistance connection with said casing, the interface between said arm means and casing thus being the only separable contact interface between said power leads; a longitudinally extending sandwich of elements held under spring pressure located between the ends of said casing and comprising, in the order named, first fully compressed spring means, arm-deforming means positioned immediately between said fully compressed spring means and said arm means and urged by said fully compressed spring means toward said arm means to deform the same inwardly when the fully compressed spring means is allowed to expand, backing means for said arm means against which said arm means bear and are expanded against said casing to establish a given low resistance contact therewith, partially compressed spring means for taking up any play in said sandwich of elements, and a fusible body which melts at a given control temperature and is engaged by said other end of said casing at the sides thereof to efficiently receive heat externally of the casing thereto, said backing means being located between said fully compressed spring means and partially compressed spring means so that the position of said backing means is fixed within said sandwich of elements as long as said fully compressed means remains fully compressed, whereby the contact resistance between said arm means and casing do not vary with the degree of compression of said partially compressed spring means; the melting of said fusible body at first causing the partially compressed spring means to expand at said control temperature after which said fully compressed spring means forces said arm-deforming means against said arm means to disengage the same from said casing.
Claim 21
Dependent Claim
377 words
An ambient thermal cut-off link comprising: a casing of electrically conductive material having inner conductive surfaces; a first power lead extending longitudinally into one end of said casing at a point where it is insulated therefrom, said first power lead terminating within said casing in laterally outwardly extending, inwardly deformable contact-forming arm means making a low resistance contact with said curved inner conductive surface of said casing and which are integral with said first power lead so that no separable contact interface is formed therewith; a second power lead extending longitudinally into the other end of said casing and making a permanent low resistance connection with said casing, the interface between said arm means and casing thus being the only separable contact interface between said power leads; a longitudinally extending sandwich of elements held under spring pressure located between the ends of said casing and comprising, in the order named, first fully compressed spring means, arm-deforming means positioned immediately between said fully compressed spring means and said arm means and urged by said fully compressed spring means toward said arm means to deform the same inwardly when the fully compressed spring means is allowed to expand, backing means for said arm means against which said arm means bear and are expanded against said casing to establish a given low resistance contact therewith, partially compressed spring means for taking up any play in said sandwich of elements, and a fusible body which melts at a given control temperature and is engaged by said other end of said casing at the sides thereof to efficiently receive heat externally of the casing thereto, said backing means being located between said fully compressed spring means and partially compressed spring means so that the position of said backing means is fixed within said sandwich of elements as long as said fully compressed means remains fully compressed, whereby the contact resistance between said arm means and casing do not vary with the degree of compression of said partially compressed spring means; the melting of said fusible body at first causing the partially compressed spring means to expand at said control temperature after which said fully compressed spring means forces said arm-deforming means against said arm means to disengage the same from said casing.
Claim 22
Independent Claim
385 words
A method of making an ambient thermally actuated switch comprising a casing of electrically conductive material having at least one initially open portion to receive switch-forming elements during the assembly of the switch; a first exposed power conductor within and insulated from said open portion of said casing and associated laterally outwardly inclining contact-forming arm means initially in electrical contact with a conductive surface associated with said casing; a sandwich of elements within said casing, said sandwich of elements including arm-deforming means contiguous to one side of said contact-forming arm means and adapted when forced thereagainst with a given force to contract and bend said contact-forming arm means away from said conductive surface, a backing member on the opposite side of contact-forming arm means against which member said contact-forming arm means are forced to expand the same into good electrical contact with said conductive surface, spring means, and a fusible body of material which melts at a given control temperature, said spring means being in a stressed condition while the fusible body remains unmelted and moving to an unstressed state to push said arm-deforming means against said arm means to move the same out of contact with said conductive surface; and closure means closing said initially open portion of said casing so that it maintains said spring means in said stressed condition to force said contact-forming arm means against said backing member; said method comprising; inserting said sandwich of elements and said first power conductor and associated contact-forming means into said casing, then externally forcing said closure means against said sandwich of elements and said first power conductor and contact-forming arm means toward said backing member, to stress said spring means and force said contact-forming arm means against said backing member so as to expand said contact-forming arm means into forced engagement with said casing, adjusting said force against said first power conductor and contact-forming arm means to a value such that the contact resistance measured between said casing and said contact-forming arm means is at a desirably low predetermined value, and, while maintaining said adjusted force on said first power conductor, permanently anchoring said closure means over said initially open portion of said casing to fix the stress on said spring means and the pressure of said contact-forming arm means against said conductive surface.
Claim 23
Independent Claim
385 words
A method of making an ambient thermally actuated switch comprising a casing of electrically conductive material having at least one initially open portion to receive switch-forming elements during the assembly of the switch; a first exposed power conductor within and insulated from said open portion of said casing and associated laterally outwardly inclining contact-forming arm means initially in electrical contact with a conductive surface associated with said casing; a sandwich of elements within said casing, said sandwich of elements including arm-deforming means contiguous to one side of said contact-forming arm means and adapted when forced thereagainst with a given force to contract and bend said contact-forming arm means away from said conductive surface, a backing member on the opposite side of contact-forming arm means against which member said contact-forming arm means are forced to expand the same into good electrical contact with said conductive surface, spring means, and a fusible body of material which melts at a given control temperature, said spring means being in a stressed condition while the fusible body remains unmelted and moving to an unstressed state to push said arm-deforming means against said arm means to move the same out of contact with said conductive surface; and closure means closing said initially open portion of said casing so that it maintains said spring means in said stressed condition to force said contact-forming arm means against said backing member; said method comprising; inserting said sandwich of elements and said first power conductor and associated contact-forming means into said casing, then externally forcing said closure means against said sandwich of elements and said first power conductor and contact-forming arm means toward said backing member, to stress said spring means and force said contact-forming arm means against said backing member so as to expand said contact-forming arm means into forced engagement with said casing, adjusting said force against said first power conductor and contact-forming arm means to a value such that the contact resistance measured between said casing and said contact-forming arm means is at a desirably low predetermined value, and, while maintaining said adjusted force on said first power conductor, permanently anchoring said closure means over said initially open portion of said casing to fix the stress on said spring means and the pressure of said contact-forming arm means against said conductive surface.
Claim 24
Dependent Claim
55 words
The method of claim 19 wherein said closure means is a resilient contractible member which is initially inserted within said open portion of said casing where it loosely surrounds said first power conductor, said anchoring of said closure means contracting said casing tightly around said first power conductor before said external forces thereon are released.
Claim 25
Dependent Claim
42 words
The method of claim 20 wherein said closure means is anchored over said initially open portion of said casing by crimping the casing walls snugly around an external portion of the closure means to contract the same around said first power conductor.
Claim 26
Dependent Claim
23 words
The method of claim 19 wherein said casing is a cylindrical casing and said conductive surface is the inner surface of said casing.
Claim 27
Dependent Claim
28 words
The method of claim 19 wherein said contact-forming arm means is an integral portion of said power conductor so that there is no contact interface between the same.
Claim 28
Independent Claim
72 words
The method of any of claims 19 through 23 wherein said contact-forming arm means incline laterally outwardly in a direction away from said open portion of said casing, said backing member being on the outside of said arm means and said arm-deforming means being on the inside of said arm means, and said contact-forming arm means being forced inwardly by said externally applied force prior to the anchoring of said closure means.
Claim 29
Dependent Claim
88 words
The method of claim 20 or 21 wherein, after said closure means has been anchored in place to fix the stress on the spring means and the pressure of said contact-forming arm means against said conductive surface, applying a synthetic plastic material to the lines of juncture between said closure means and said casing and first power conductor, and after releasing the external forces on said closure means and first power conductor, placing the switch in an environment elevated to the curing temperature of said synthetic plastic material.
Claim 30
Dependent Claim
302 words
An ambient thermal actuated cut-off link comprising: a casing of electrically conductive material; a first power lead exposed to the outside of said casing through an opening in said casing at a point where it is insulated therefrom, said first power lead having at the inner end thereof laterally outwardly extending, inwardly deformable contact-forming arm means making a low resistance contact with an inner conductive surface associated with said casing; a second exposed power lead making a permanent low resistance connection with said casing; a sandwich of serially located elements urged under spring pressure between fixed spaced points in said casing and comprising stressed spring means, arm-deforming means on one side of said arm means which arm-deforming means is urged by said spring means toward said arm means to deform the same inwardly when the spring means is allowed to move to the unstressed state thereof, backing means for said arm means on the other side of the same and against which backing means said arm means is urged to expand the same against said casing to establish a given low resistance contact therewith, and a fusible body which melts at a given control temperature, the melting of said body of meltable material at said control temperature causing said spring means to move to an unstressed state to force said arm-deforming means against said contact-forming means to bend the same away from said casing; and closure means anchored in and sealing said casing opening, said closure means being a resilient contracted member into which said first power lead extends and around which the defining walls of said casing opening extend to contract the same around the said first power lead to hold the same in a position where the contact-forming arms at the inner end thereof are forced against said backing means.
Claim 31
Dependent Claim
302 words
An ambient thermal actuated cut-off link comprising: a casing of electrically conductive material; a first power lead exposed to the outside of said casing through an opening in said casing at a point where it is insulated therefrom, said first power lead having at the inner end thereof laterally outwardly extending, inwardly deformable contact-forming arm means making a low resistance contact with an inner conductive surface associated with said casing; a second exposed power lead making a permanent low resistance connection with said casing; a sandwich of serially located elements urged under spring pressure between fixed spaced points in said casing and comprising stressed spring means, arm-deforming means on one side of said arm means which arm-deforming means is urged by said spring means toward said arm means to deform the same inwardly when the spring means is allowed to move to the unstressed state thereof, backing means for said arm means on the other side of the same and against which backing means said arm means is urged to expand the same against said casing to establish a given low resistance contact therewith, and a fusible body which melts at a given control temperature, the melting of said body of meltable material at said control temperature causing said spring means to move to an unstressed state to force said arm-deforming means against said contact-forming means to bend the same away from said casing; and closure means anchored in and sealing said casing opening, said closure means being a resilient contracted member into which said first power lead extends and around which the defining walls of said casing opening extend to contract the same around the said first power lead to hold the same in a position where the contact-forming arms at the inner end thereof are forced against said backing means.
Claim 32
Dependent Claim
39 words
The cut-off link of claim 26 wherein a sealing cement covers and seals over adjacent surfaces of said closure means and said casing and first power lead, to hermetically seal the interior of the casing from the surrounding atmosphere.
Claim 33
Dependent Claim
42 words
The ambient thermal cut-off link of claim 26 wherein said contact-forming arm means forms an integral part of said first power lead so that the interface between said arm means and casing is the only separable contact interface between said power leads.
Claim 34
Dependent Claim
57 words
The cut-off link or switch of claims 1, 15, 16 or 26 wherein said fusible body is a body of fusible granular material compressed into one end of the casing so it expands and closely engages the exposed inner surfaces of the casing, to enable external heat to readily pass into said compressed body of fusible material.
Claim 35
Dependent Claim
35 words
The thermal switch or cut-off link of claims 2, 7, 18, 19 or 28 wherein said contact-forming arm means and said first power lead form a monolithic body formed from the same body of material.
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USPTO Annuity & Maintenance Windows
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|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-07-27 | 1985-01-26 | 1985-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-27 | 1989-01-26 | 1989-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-27 | 1993-01-26 | 1993-07-28 | $7700.00 | Window Closed / Lapsed |