EP4371139A1 - Temperature limiting device - Google Patents
Temperature limiting deviceInfo
- Publication number
- EP4371139A1 EP4371139A1 EP22757702.0A EP22757702A EP4371139A1 EP 4371139 A1 EP4371139 A1 EP 4371139A1 EP 22757702 A EP22757702 A EP 22757702A EP 4371139 A1 EP4371139 A1 EP 4371139A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- lid
- resin
- disc
- protective cover
- spring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229920005989 resin Polymers 0.000 claims abstract description 29
- 239000011347 resin Substances 0.000 claims abstract description 29
- 230000001681 protective effect Effects 0.000 claims abstract description 18
- 239000011810 insulating material Substances 0.000 claims abstract description 9
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 4
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 239000011248 coating agent Substances 0.000 claims description 8
- 238000000576 coating method Methods 0.000 claims description 8
- 239000004020 conductor Substances 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 238000006116 polymerization reaction Methods 0.000 claims description 6
- 239000004593 Epoxy Substances 0.000 claims description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- 230000008878 coupling Effects 0.000 claims description 4
- 238000010168 coupling process Methods 0.000 claims description 4
- 238000005859 coupling reaction Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000011888 foil Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 230000007246 mechanism Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 235000019577 caloric intake Nutrition 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 claims 1
- 239000012141 concentrate Substances 0.000 claims 1
- 230000002708 enhancing effect Effects 0.000 claims 1
- 230000004048 modification Effects 0.000 claims 1
- 238000012986 modification Methods 0.000 claims 1
- 239000013307 optical fiber Substances 0.000 claims 1
- 229920001225 polyester resin Polymers 0.000 claims 1
- 239000004645 polyester resin Substances 0.000 claims 1
- 239000007788 liquid Substances 0.000 description 6
- 239000010970 precious metal Substances 0.000 description 4
- 125000006850 spacer group Chemical group 0.000 description 4
- 229910001369 Brass Inorganic materials 0.000 description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 3
- 239000010951 brass Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 239000004332 silver Substances 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 229920000728 polyester Polymers 0.000 description 2
- 229910000906 Bronze Inorganic materials 0.000 description 1
- 241000241551 Philoxerus vermicularis Species 0.000 description 1
- 239000010974 bronze Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/32—Thermally-sensitive members
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
- H01H37/5427—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting encapsulated in sealed miniaturised housing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/04—Bases; Housings; Mountings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/32—Thermally-sensitive members
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
- H01H2037/5463—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting the bimetallic snap element forming part of switched circuit
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H37/00—Thermally-actuated switches
- H01H37/02—Details
- H01H37/32—Thermally-sensitive members
- H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
- H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
- H01H2037/5481—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting the bimetallic snap element being mounted on the contact spring
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
- H01H9/02—Bases, casings, or covers
- H01H9/04—Dustproof, splashproof, drip-proof, waterproof, or flameproof casings
Definitions
- the present invention relates to a temperature limiting device for protecting electrical apparatuses and the like, as well as a method for manufacturing said device.
- the bimetallic disc is capable of moving from a low temperature position to a high temperature position in which it acts on the spring-loaded disc to open the electrical circuit and thereby interrupt heating.
- a temperature limiting device of this type is shown for example in European patent EP 0 678891.
- This temperature limiter comprises an external container defining a cup-shaped housing, closed by a lid, inside which a bimetallic disc and a spring-loaded disc are arranged in a stack.
- the lid carries the fixed contact of the changeover switch, while the spring-loaded disc carries the movable contact.
- the movable contact In the normal operating condition, i.e. at low temperature, the movable contact is pressed by the spring-loaded disc against the fixed contact and thus closes the electrical circuit, allowing the current to flow.
- the bimetallic disc reverses its position, consequently moving the spring-loaded disc. In this way the movable contact is detached from the fixed contact and the electrical circuit opens, interrupting the flow of current and heating.
- the bimetallic thermal switch is usually inserted inside the stator winding of the electric motor, during the motor manufacturing step, so that the thermal switch is in direct thermal coupling with the winding.
- the used resins require the use of a kiln to complete the polymerization, or long curing times at room temperature. This involves a pause in the production flow, which is necessary for the the heat treatment to be completed, be it at room temperature or at high temperature. The production process is affected by this pause, as a continuous flow of production is not achieved.
- the aim of the present invention is to solve the aforementioned problems, by devising a temperature limiting device that has an outer container coating that achieves optimal protection from external agents.
- a further object of the invention is to provide a temperature limiting device of simple construction and functional design, having reliable operation, versatile use, as well as relatively inexpensive cost.
- the temperature limiting device comprises an external container defining a cup-shaped housing, closed by a lid, inside which a spring-loaded disc and a bimetallic disc are stacked.
- said outer container is made of conductive material.
- said lid is made of insulating material.
- said lid is made of a combination of materials such as to be isolated with respect to said external container.
- the bimetallic disc is axially associated with said spring-loaded disc.
- the temperature limiting device comprises at least one fixed contact integral with said lid of the outer container and protruding for a portion thereof above the same lid and at least one movable contact integral with said spring-loaded disc.
- the temperature limiting device comprises a protective cover of insulating material which extends to cover said lid, said portion of the fixed contact protruding above the lid and a curved edge of said outer container and is made of resin adapted to polymerize by exposure to a source of UV rays.
- said UV rays have a wavelength in the range 320-450 nm.
- said UV source consists of UV lamps with an intensity in the range 50-200 mW/cm 2 .
- said protective cover is made by means of an epoxy-based resin or epoxy polyester with a trigger and hardening mechanism by means of said UV rays.
- said protective cover is dome-shaped and at least partially embeds the connection cables of the temperature limiting device.
- said curved edge faces the inside of said outer container so as to retain said lid.
- said movable contact comprises a movable bridge integral, by axial securing means, to said spring-loaded disc and to said bimetallic disc, tightened in pack.
- said movable bridge has a circular shape and it can be brought in abutment to a pair of fixed contacts.
- said bimetallic disc is made up of a foil made by coupling iron and copper.
- said bimetallic disc is arch-shaped, so as to abut peripherally on the edge of said spring-loaded disc.
- the present invention also relates to a method for manufacturing a temperature limiting device which provides for coating at least the upper part of the external container of conductive material of the device with a protective cover made of resin suitable for polymerizing through exposure to a source of UV rays.
- said protective cover of insulating material extends to cover a lid of said external container of conductive material, a portion of a fixed contact integral with said lid of the external container and protruding above said lid and a curved edge of said external container.
- Figure 1 shows an axial sectional view of the temperature limiting device according to the present invention
- Figure 2 shows the same axial sectional view of the temperature limiting device in a different operative configuration
- Figure 3 shows a similar axial sectional view of a different embodiment of the temperature limiting device according to the present invention.
- the temperature limiting device according to the present invention is indicated as a whole with the reference numeral 1.
- the temperature limiting device comprises an external container 2 defining a cup-shaped housing 3.
- the housing 3 of the external container 2 is closed at the top by a lid 4, retained by a peripheral curved edge 5 of the external container 2.
- the external container 2 is made of conductive material, for example brass.
- the lid 4 is made of insulating material, such as for example ceramic material and the like, or alternatively of a combination of materials, including metal, but such as to be insulated with respect to the external container 2.
- a spring-loaded disc 6 and a bimetallic disc 7 are arranged in a stack.
- the spring-loaded disc 6 is preferably made of stainless steel coated with a precious material, for example silver; the bimetallic disc 7 is preferably constituted by a foil made by coupling iron and copper.
- the lid 4 is tightened against a spacer member 8 of annular shape, which in turn rests peripherally on an annular shoulder 9 internally shaped by the external container 2.
- a spacer member 8 of annular shape, which in turn rests peripherally on an annular shoulder 9 internally shaped by the external container 2.
- the lid 4 and the spacer member 8 are packed against the annular shoulder 9 by the curved edge 5 of the outer container 2, suitably riveted.
- the spacer member 8 is made, for example, of brass or the like.
- the cover 4 carries axially inserted, in a way known per se, a fixed contact 10 of the thermal switch; the spring-loaded disc 6 carries in turn axially inserted a movable contact
- the fixed contact 10 is protruding below the lid 4; the movable contact 11 is protruding above the bimetallic disc 7, through an axial hole made in the same bimetallic disc 7.
- the contacts 10, 11 are preferably made of precious metal, for example silver, or an alloy thereof, or a composition of a precious metal with a conductive metal, for example copper rod and silver head.
- the outer container 2 is coated above the lid 4 with a protective dome-shaped cover 12 of insulating material.
- the protective dome 12 extends to completely cover the lid 4, the portion of the fixed contact 10 protruding above the lid 4 and the curved edge 5 of the outer container 2, or at least the inner part of said curved edge 5.
- the protective dome 12 also embeds the cables 13, 14 connecting respectively to the outer container 2 and to the fixed contact 10. It should be noted that it is not necessary for the cable 13 for connecting to the outer container 2 to be covered by the protection dome
- the protective dome 12 is made of a resin adapted to polymerize by exposure to a source of UV rays.
- said resin adapted to polymerize by exposure to a source of UV rays consists of an epoxy-based resin or epoxy-polyester with triggering and hardening ultraviolet mechanism.
- the UV source preferably consists of UV lamps with a wavelength 320-450 nm, with intensity in the range 50-200 mW/cm 2 .
- the spring-loaded disc 6 and the bimetallic disc 7 are centered and secured between the base of the housing 3 defined by the outer container 2 of conductive material and the lid 4 carrying the fixed contact 10 integrated.
- the spring-loaded disc 6 constitutes the element through which the electric current passes and supports the movable contact 11 which is kept under constant pressure against the fixed contact 10 (Fig. 1 ).
- the bimetallic disc 7, supported by the movable contact 11 that passes therethrough, is able to react to any changes in the temperature of the apparatus to be protected.
- the bimetallic disc 7 clicks into the reverse position, with the concavity downwardly facing, and pushes the spring-loaded disc 6 downwards (Fig. 2).
- FIG. 3 shows a different embodiment of the temperature limiting device in which the lid 4 of the outer container 2 carries a pair of fixed contacts, for clarity indicated with reference numerals 10a and 10b.
- the fixed contacts 10a and 10b cross the lid 4 in parallel positions with respect to each other and are protruding for a portion thereof from the lid 4 itself.
- a movable bridge 15 Inside the housing 3 defined by the outer container 2 is arranged a movable bridge 15, of circular shape, adapted to be brought in abutment with the fixed contacts 10a and 10b.
- the movable bridge 15 is made integral, by means of an axial rivet 16, to the tightly packed spring-loaded disc 6 and bimetallic disc 7. Basically, the movable bridge 15 performs the same function performed, in the previous solution, by the movable contact 11.
- the movable bridge 15 is preferably made of brass, bronze or the like, coupled with a precious metal or an alloy thereof such as silver or the like, with or without a precious metal coating.
- the spring-loaded disc 6 is secured against a circular seat obtained inside the housing 3 by a spacer ring 17.
- the temperature limiting device according to the present invention achieves the purpose of having a coating of the outer container which provides optimal protection against external agents, in particular such as to prevent the entry of chemicals and other liquid
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Thermally Actuated Switches (AREA)
- Glass Compositions (AREA)
- Inorganic Insulating Materials (AREA)
- Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
Abstract
The temperature limiting device comprises an outer container (2) defining a cup-shaped housing (3), closed by a lid (4), inside which a spring-loaded disc (6) and a bimetallic disc (7) are stacked. The lid (4) of the outer container (2) and the spring-loaded disc (6) have, integrally therewith, a fixed contact (10) and at least one movable contact (11, 15) respectively. A protective cover (12) made of resin insulating material suitable for polymerizing by exposure to a source of UV rays is placed above the lid (4).
Description
Description
TEMPERATURE LIMITING DEVICE Technical field
[01] The present invention relates to a temperature limiting device for protecting electrical apparatuses and the like, as well as a method for manufacturing said device.
Prior art
[02] It is currently known, in the technical field concerning the manufacture of temperature limiters suitable for ensuring the thermal protection of electrical devices or components of apparatuses such as electric motors and the like, the use of anti-surge temperature limiters based on the use of a bimetallic disc adapted to switch the configuration of a spring-loaded disc that correspondingly closes or opens an electrical circuit of the device to be protected. Such temperature limiting devices, in the specified sector, are also referred to as bimetallic thermal switches.
[03] In particular, the bimetallic disc is capable of moving from a low temperature position to a high temperature position in which it acts on the spring-loaded disc to open the electrical circuit and thereby interrupt heating.
[04] A temperature limiting device of this type is shown for example in European patent EP 0 678891.
[05] Further examples of temperature limiters of the aforementioned type are shown in documents DE 102013102006 and DE 102004014028.
[06] This temperature limiter comprises an external container defining a cup-shaped housing, closed by a lid, inside which a bimetallic disc and a spring-loaded disc are arranged in a stack. The lid carries the fixed contact of the changeover switch, while the spring-loaded disc carries the movable contact. In the normal operating condition, i.e. at low temperature, the movable contact is pressed by the spring-loaded disc against the fixed contact and thus closes the electrical circuit, allowing the current to flow. On the other hand, when the temperature exceeds a predetermined threshold value, the bimetallic disc reverses its position, consequently moving the spring-loaded disc. In this way the movable contact is detached from the fixed contact and the electrical circuit opens, interrupting the flow of current and heating.
[07] In operation, the bimetallic thermal switch is usually inserted inside the stator winding of the electric motor, during the motor manufacturing step, so that the thermal switch is in direct thermal coupling with the winding.
[08] However, it should be noted that the need to ensure mechanical solidity and fastening to the winding often involves the need to impregnate the motor stator using chemical products, such as solvent-based paints, water-based paints, resins and the like. During this manufacturing step, there is therefore a high risk of penetration inside the bimetallic
thermal switch of the chemicals used for impregnating the stator, with consequent malfunction of the switch itself. To prevent this risk, bimetallic thermal switches are usually protected by a resin cover. This resin cover, once solidified, covers the parts of the switch potentially at risk of infiltration and ensures safe use, even in the case of impregnation with the aforementioned chemicals.
[09] For this purpose, resins which polymerize under the effect of temperature, for example mono or bi-component epoxy resins, silicone resins and the like, are currently used for finishing bimetallic thermal switches. However, these resins have evident limitations both in terms of the production process and the quality of the final result.
[10] As for the production process, the used resins require the use of a kiln to complete the polymerization, or long curing times at room temperature. This involves a pause in the production flow, which is necessary for the the heat treatment to be completed, be it at room temperature or at high temperature. The production process is affected by this pause, as a continuous flow of production is not achieved.
[11] In addition, resins of this type are often very susceptible to room temperature, with high viscosity variations, due to the variation of the temperature. This peculiarity implies the need to regulate the temperature of the work areas, in order to avoid that the same resin is almost liquid in the hot periods of the year and very viscous in the cold periods, with evident complications in the dosing and process phase.
[12] Another problem complained of in the specified sector, in relation to the type of product and manufacturing process used in the prior art, is the so-called phenomenon of "capillarity". In fact, it has been noted that, once applied above the bimetallic thermal switch, the liquid resin infiltrates between the cracks between one component and the other, in particular between the lid and the outer container, in its riveted portion, or between the lid and the rivet that acts as an electrical contact.
[13] This phenomenon is the more definite, the more liquid the resin is and longer the first polymerization time, so-called "gel-time". If the resin penetrates inside the bimetallic thermal switch, it can prevent its correct operation, with serious consequences for the safety of the apparatuses in which it is installed.
Disclosure
[14] The aim of the present invention is to solve the aforementioned problems, by devising a temperature limiting device that has an outer container coating that achieves optimal protection from external agents.
[15] As part of this aim, it is a further object of the invention to provide a temperature limiting device provided with a coating that prevents the entry of chemicals and other liquid substances into the housing containing the operating components of the same device.
[16] A further object of the invention is to provide a temperature limiting device of simple
construction and functional design, having reliable operation, versatile use, as well as relatively inexpensive cost.
[17] The aforementioned objects are achieved, according to the present invention, by the temperature limiting device according to claim 1.
[18] The temperature limiting device comprises an external container defining a cup-shaped housing, closed by a lid, inside which a spring-loaded disc and a bimetallic disc are stacked.
[19] Preferably said outer container is made of conductive material.
[20] Preferably said lid is made of insulating material.
[21] Alternatively, said lid is made of a combination of materials such as to be isolated with respect to said external container.
[22] The bimetallic disc is axially associated with said spring-loaded disc.
[23] The temperature limiting device comprises at least one fixed contact integral with said lid of the outer container and protruding for a portion thereof above the same lid and at least one movable contact integral with said spring-loaded disc.
[24] According to the present invention, the temperature limiting device comprises a protective cover of insulating material which extends to cover said lid, said portion of the fixed contact protruding above the lid and a curved edge of said outer container and is made of resin adapted to polymerize by exposure to a source of UV rays.
[25] Advantageously, said UV rays have a wavelength in the range 320-450 nm.
[26] Preferably said UV source consists of UV lamps with an intensity in the range 50-200 mW/cm2.
[27] The use of a resin that polymerizes through exposure to a source of UV rays reduces considerably the time of the production process, allowing an application in line with continuous flow and without breaks due to long thermal cycles.
[28] Preferably said protective cover is made by means of an epoxy-based resin or epoxy polyester with a trigger and hardening mechanism by means of said UV rays.
[29] Preferably said protective cover is dome-shaped and at least partially embeds the connection cables of the temperature limiting device.
[30] Preferably said curved edge faces the inside of said outer container so as to retain said lid.
[31] According to an embodiment of the invention, said movable contact comprises a movable bridge integral, by axial securing means, to said spring-loaded disc and to said bimetallic disc, tightened in pack.
[32] Preferably said movable bridge has a circular shape and it can be brought in abutment to a pair of fixed contacts.
[33] Preferably said bimetallic disc is made up of a foil made by coupling iron and copper.
[34] Preferably said bimetallic disc is arch-shaped, so as to abut peripherally on the edge of said spring-loaded disc.
[35] The present invention also relates to a method for manufacturing a temperature limiting device which provides for coating at least the upper part of the external container of conductive material of the device with a protective cover made of resin suitable for polymerizing through exposure to a source of UV rays.
[36] Advantageously, said protective cover of insulating material extends to cover a lid of said external container of conductive material, a portion of a fixed contact integral with said lid of the external container and protruding above said lid and a curved edge of said external container.
Description of drawings
[37] The details of the invention will become more evident from the detailed description of preferred embodiments of the temperature limiting device, illustrated by way of example in the accompanying drawings, wherein:
Figure 1 shows an axial sectional view of the temperature limiting device according to the present invention;
Figure 2 shows the same axial sectional view of the temperature limiting device in a different operative configuration;
Figure 3 shows a similar axial sectional view of a different embodiment of the temperature limiting device according to the present invention.
Description of embodiments of the invention
[38] With particular reference to these figures, the temperature limiting device according to the present invention is indicated as a whole with the reference numeral 1.
[39] The temperature limiting device comprises an external container 2 defining a cup-shaped housing 3. The housing 3 of the external container 2 is closed at the top by a lid 4, retained by a peripheral curved edge 5 of the external container 2. The external container 2 is made of conductive material, for example brass. The lid 4 is made of insulating material, such as for example ceramic material and the like, or alternatively of a combination of materials, including metal, but such as to be insulated with respect to the external container 2.
[40] Inside the housing 3 of the external container 2 a spring-loaded disc 6 and a bimetallic disc 7 are arranged in a stack. In the normal operating condition, the spring-loaded disc 6, having a slightly arched shape, rests peripherally on the bottom of the housing 3 of the external container 2; the bimetallic disc 7, having a more arched shape, rests peripherally on the edge of the same spring-loaded disc 6.
[41] The spring-loaded disc 6 is preferably made of stainless steel coated with a precious material, for example silver; the bimetallic disc 7 is preferably constituted by a foil made by
coupling iron and copper.
[42] The lid 4 is tightened against a spacer member 8 of annular shape, which in turn rests peripherally on an annular shoulder 9 internally shaped by the external container 2. In practice, the lid 4 and the spacer member 8 are packed against the annular shoulder 9 by the curved edge 5 of the outer container 2, suitably riveted. The spacer member 8 is made, for example, of brass or the like.
[43] The cover 4 carries axially inserted, in a way known per se, a fixed contact 10 of the thermal switch; the spring-loaded disc 6 carries in turn axially inserted a movable contact
11 of the thermal switch. The fixed contact 10 is protruding below the lid 4; the movable contact 11 is protruding above the bimetallic disc 7, through an axial hole made in the same bimetallic disc 7.
[44] The contacts 10, 11 are preferably made of precious metal, for example silver, or an alloy thereof, or a composition of a precious metal with a conductive metal, for example copper rod and silver head.
[45] In the normal operating condition, i.e. at low temperature, the movable contact 11 is elastically pushed by the spring-loaded disc 6 against the fixed contact 10 and thus closes the electrical circuit, allowing the passage of current, as specified below (see Fig. 1).
[46] The outer container 2 is coated above the lid 4 with a protective dome-shaped cover 12 of insulating material. The protective dome 12 extends to completely cover the lid 4, the portion of the fixed contact 10 protruding above the lid 4 and the curved edge 5 of the outer container 2, or at least the inner part of said curved edge 5.
[47] The protective dome 12 also embeds the cables 13, 14 connecting respectively to the outer container 2 and to the fixed contact 10. It should be noted that it is not necessary for the cable 13 for connecting to the outer container 2 to be covered by the protection dome
12 since the fundamental function of this coating is the protection of the internal components of the device from the penetration of liquids and not the protection of the welds.
[48] According to the present invention, the protective dome 12 is made of a resin adapted to polymerize by exposure to a source of UV rays.
[49] In particular, said resin adapted to polymerize by exposure to a source of UV rays consists of an epoxy-based resin or epoxy-polyester with triggering and hardening ultraviolet mechanism.
[50] The UV source preferably consists of UV lamps with a wavelength 320-450 nm, with intensity in the range 50-200 mW/cm2.
[51] The operation of the temperature limiting device according to the present invention is readily understandable from the foregoing description.
[52] In the normal operating condition, the spring-loaded disc 6 and the bimetallic disc 7 are
centered and secured between the base of the housing 3 defined by the outer container 2 of conductive material and the lid 4 carrying the fixed contact 10 integrated.
[53] The spring-loaded disc 6 constitutes the element through which the electric current passes and supports the movable contact 11 which is kept under constant pressure against the fixed contact 10 (Fig. 1 ).
[54] The bimetallic disc 7, supported by the movable contact 11 that passes therethrough, is able to react to any changes in the temperature of the apparatus to be protected. When a predetermined switching temperature is reached, the bimetallic disc 7 clicks into the reverse position, with the concavity downwardly facing, and pushes the spring-loaded disc 6 downwards (Fig. 2).
[55] In this way, the contact between the fixed and mobile contacts 10, 11 opens instantly and therefore interrupts the increase in temperature in the apparatus to be protected. Conversely, when the temperature drops and reaches the preset normal operating value, the bimetallic disc 7 clicks again to return to the initial position and the contact closes.
[56] Fig. 3 shows a different embodiment of the temperature limiting device in which the lid 4 of the outer container 2 carries a pair of fixed contacts, for clarity indicated with reference numerals 10a and 10b. The fixed contacts 10a and 10b cross the lid 4 in parallel positions with respect to each other and are protruding for a portion thereof from the lid 4 itself.
[57] Inside the housing 3 defined by the outer container 2 is arranged a movable bridge 15, of circular shape, adapted to be brought in abutment with the fixed contacts 10a and 10b. The movable bridge 15 is made integral, by means of an axial rivet 16, to the tightly packed spring-loaded disc 6 and bimetallic disc 7. Basically, the movable bridge 15 performs the same function performed, in the previous solution, by the movable contact 11.
[58] The movable bridge 15 is preferably made of brass, bronze or the like, coupled with a precious metal or an alloy thereof such as silver or the like, with or without a precious metal coating.
[59] The spring-loaded disc 6 is secured against a circular seat obtained inside the housing 3 by a spacer ring 17.
[60] As in the previous case, if there is a change in the temperature of the apparatus to be protected, such as to exceed a predetermined switching temperature, the bimetallic disc 7 clicks into the reverse position, with the concavity downwardly facing, and pushes the spring-loaded disc 6 downwards, opening the contact between the movable bridge 15 and the fixed contacts 10a and 10b.
[61] The temperature limiting device according to the present invention achieves the purpose of having a coating of the outer container which provides optimal protection against external agents, in particular such as to prevent the entry of chemicals and other liquid
Claims
substances into the housing containing the operative components of the same device.
[62] This result is achieved through the inventive idea of creating the coating of the external container of the device by means of a resin capable of polymerizing through exposure to a source of UV rays.
[63] The use of a resin that polymerizes through exposure to a source of UV rays reduces considerably the time of the production process, allowing an application in line with continuous flow and without breaks due to long thermal cycles.
[64] In practice, it has been found that the polymerization process according to the invention permits to change over from a time of 30-90 minutes normally required in the known art to a time of a few minutes.
[65] Furthermore, resins of the specified type make it possible to reach the so-called "gel time", that is the time of the first polymerization, in a few seconds, quickly stopping the phenomenon of capillarity and consequently significantly reducing the risk that the resin penetrates inside the bimetallic switch, impairing its operation.
[66] It should also be noted that the resins in question are usually less subject to variations in viscosity linked to variations in the ambient temperature.
[67] According to a further advantageous aspect of the invention, it is possible to use suitable UV lamps for polymerization, combined in particular with circuits made with optical fiber, to concentrate the light exactly in the portion of resin to be polymerized, obtaining rapid, precise and reduced energy intake reactions.
[68] The production process therefore does not require the use of a kiln to complete the high temperature polymerization, or long curing times at room temperature.
[69] The temperature limiting device described by way of example is susceptible of numerous modifications and variations according to the various requirements.
[70] In the practical embodiment of the invention, the materials used, as well as the shape and the dimensions, may be modified depending on needs.
[71] Should the technical features mentioned in any claim be followed by reference signs, such reference signs were included strictly with the aim of enhancing the understanding of the claims and hence they shall not be deemed restrictive in any manner whatsoever on the scope of each element identified for exemplifying purposes by such reference signs.
Claims
1. A temperature limiting device, comprising an external container (2) of conductive material, defining a cup-shaped housing (3) closed by a lid (4), inside which are stacked a spring-loaded disc (6); a bimetallic disc (7) associated with said spring-loaded disc (6); at least one fixed contact (10) integral with said lid (4) of the outer container (2) and protruding for a portion thereof above the same lid (4); at least one movable contact (11, 15) integral with said spring-loaded disc (6); a protective cover (12) of insulating material extending to cover said lid (4), said portion of the fixed contact (10) protruding above the same lid (4) and a curved edge (5) of said outer container (2) facing inwardly the same outer container (2); characterized in that said protective cover (12) is made of resin capable of polymerizing through exposure to a source of UV rays.
2. The device of claim 1, wherein said protective cover (12) is made of resin adapted to polymerize by exposure to a source of UV rays having a wavelength in the range 320-450 nm.
3. The device of claim 2, wherein said protective cover (12) is made of resin adapted to polymerize by exposure to a source of UV rays having an intensity in the range 50-200 mW/cm2.
4. A device of claim 1 or 2, wherein said protective cover (12) is made of an epoxy or epoxy polyester resin with a trigger and hardening mechanism by means of said UV rays.
5. The device of claim 1, wherein said protective cover (12) is dome-shaped and at least partially embeds the connection cables (13, 14) of the temperature limiting device.
6. The device of claim 1, wherein said curved edge (5) is turned towards the inner part of said external container (2) so that it holds said lid (4).
7. The device of claim 1, wherein said movable contact (15) comprises a movable bridge (15) integral, through axial securing means (16), with said spring-loaded disc (6) and with said bimetallic disc (7), tightly packed.
8. The device of claim 7, wherein said movable bridge (15) is circular and capable to be moved against a pair of fixed contacts (10a, 10b).
9. The device of claim 1, wherein said bimetallic disc (7) consists of a foil made by coupling iron and copper.
10. The device of claim 1, wherein said bimetallic disc (7) is arch-shaped, so as to rest peripherally on the edge of said spring-loaded disc (6).
1. A method for producing a temperature limiting device of any one or more of the preceding claims, characterized in that it provides for coating at least an upper part of said external container (2) of conductive material with a protective cover (12) of insulating material which extends to cover said lid (4), said portion of the fixed contact (10) protruding above the same lid (4) and said curved edge (5) of said outer container (2), said protective cover (12 ) of insulating material being made of resin suitable to polymerize through exposure to a source of UV rays.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT102021000018770A IT202100018770A1 (en) | 2021-07-15 | 2021-07-15 | TEMPERATURE LIMITER DEVICE |
PCT/IT2022/050209 WO2023286102A1 (en) | 2021-07-15 | 2022-07-15 | Temperature limiting device |
Publications (1)
Publication Number | Publication Date |
---|---|
EP4371139A1 true EP4371139A1 (en) | 2024-05-22 |
Family
ID=78086728
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP22757702.0A Pending EP4371139A1 (en) | 2021-07-15 | 2022-07-15 | Temperature limiting device |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP4371139A1 (en) |
IT (1) | IT202100018770A1 (en) |
WO (1) | WO2023286102A1 (en) |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04303525A (en) * | 1991-03-29 | 1992-10-27 | Omron Corp | Adhesive for switch |
DE9406806U1 (en) | 1994-04-23 | 1995-06-01 | Thermik Gerätebau GmbH, 75181 Pforzheim | Bimetal switch, in particular current-dependent switch |
DE102004014028A1 (en) * | 2004-03-19 | 2005-10-06 | Marcel Hofsaess | Protective temperature limiting switch for electrical equipment protection, has bimetallic disk which inverts against action of spring disk when temperature exceeds set point |
DE102013102006B4 (en) * | 2013-02-28 | 2015-03-05 | Marcel P. HOFSAESS | Temperature-dependent switch |
JP6291931B2 (en) * | 2014-03-14 | 2018-03-14 | オムロン株式会社 | Electronic device seal structure and electromagnetic relay using the electronic device seal structure |
US9831054B2 (en) * | 2014-03-27 | 2017-11-28 | Littelfuse, Inc. | Insulated thermal cut-off device |
-
2021
- 2021-07-15 IT IT102021000018770A patent/IT202100018770A1/en unknown
-
2022
- 2022-07-15 WO PCT/IT2022/050209 patent/WO2023286102A1/en active Application Filing
- 2022-07-15 EP EP22757702.0A patent/EP4371139A1/en active Pending
Also Published As
Publication number | Publication date |
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WO2023286102A1 (en) | 2023-01-19 |
IT202100018770A1 (en) | 2023-01-15 |
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