EP1239505A2 - Thermally actuated switch with printed adhesive layer - Google Patents

Abstract

The method involves inserting a switching mechanism (13) into the lower part (14) of a switch housing (12), closing the lower part of the housing with a cover part (17) while forming at least one joint point (31), stamping on an adhesive coating (32) near the joint point so as to seal it and allowing the adhesive coating to set. The switch is heated before applying the adhesive coating. Independent claims are also included for the following: a temperature-dependent switch with adhesive layer.

Description

The present invention relates to a temperature dependent Switch with a temperature-dependent housed in a housing Rear derailleur depending on its temperature between at least two provided on the outside of the housing Connection electrodes makes an electrical connection, wherein the housing is a lower part and this is under training at least a cover part closing a seam.

The invention further relates to a method of manufacture of such a temperature-dependent switch.

Such temperature-dependent switches and methods for their Manufacture is well known from the prior art.

The known temperature-dependent switches are used as security elements used the electrical equipment from overheating and / or protect excessive current consumption. To this end the temperature-dependent switches are electrically connected in series the device to be protected switched so that the operating current flows through the temperature-dependent switch. The switches are in a thermally conductive connection to the one to be protected Device arranged so that its temperature on the switch transfers.

A bimetallic switching mechanism is arranged in the switch Depending on its temperature an electrical connection between two connection electrodes on the housing of the switch or interrupts. If the temperature is too high or too high The current-dependent switch thus opens the flow of current Current flow to the device to be protected, which then cool down again can or is protected against destruction.

Such temperature-dependent switches are, for example, in Warming plates, hair dryers etc. are used, but they are especially as safety elements in transformers, motors, Pumps etc. to find. For good thermal coupling to reach the windings to be protected the switches are often wrapped in the coils and are subject to following the same treatment steps as the coils that are used in transformers, motors, Pumps etc. can be found.

Such temperature-dependent switches have a structure a lower part and a cover part, these housing parts can be made of metal or insulating material. If both housing parts are made of metal, is between an insulation layer is provided for them, whereby as connection electrodes then immediately the lower part or the cover part can serve to which leads can then be soldered. Is only one of the two housing parts made of metal and that others made of insulating material, the metal housing part serves directly as a connection electrode, while on the housing part A separate connection electrode is attached, the one from the housing part protruding crimp flag or also a soldering head of a rivet penetrating the housing part can be. If both housing parts are made of insulating material are accordingly two separate connection electrodes required.

It is also known to have both connection electrodes on the same housing part, for example on the cover part or on the lower part, to be provided by the temperature-dependent switching mechanism over a kind of current bridge depending on the temperature in Can be connected.

When assembling such temperature-dependent switches the temperature-dependent switching mechanism is inserted in the lower part, which is then closed by the cover part. this happens usually in that a raised edge of the lower part is flanged if the lower part is made of metal, or hot pressed if the lower part made of insulating material consists. It is also known that the cover part and the lower part fit into one another to push and connect to each other via detents.

The connection point between the lower part and the cover part represents a seam that gives rise to problems with tightness can give. The temperature-dependent switches are namely often used in dusty or damp environments, so that dust and moisture must be prevented from entering the Penetrate inside the switch and impair its function. In addition, these switches must have an appropriate one Have dielectric strength, because over the switches can large voltages are present which do not cause the switch to break down may lead in the area of the interface.

Various possibilities are now described in the prior art, temperature-dependent exposed to the corresponding load Switches optionally sealed on customer request become.

The usual procedure for manufacturers of such switches is that these switches including their connection technology, i.e. the soldered connection leads or other leads, are made before certain lots of the like Assembled switch with a special seal become.

DE 196 09 310 A1 describes a temperature-dependent switch known in which the lower part made of insulating material and Cover part is made of metal. The seal between the lower part and the cover part are made using a hot-pressed Edge. In everyday operation it has now emerged that this hot-pressed edge is often not sufficient for the required Tightness against dust and moisture ensures.

DE 196 23 570 A1 describes a temperature-dependent switch known in the lower part and cover part made of metal are, with a Kapton film between these two housing parts not just for the necessary electrical insulation but also for the tightness against dust and moisture should worry. For this purpose is a raised edge of the lower part flanged onto the cover part. Here too it turned out that with these and comparable switches with a flanged edge even under the tightness certain conditions is not sufficient if an insulating sheet is provided.

DE 41 39 091 A1 describes a temperature-dependent switch known to increase the dielectric strength and Protection against dust and moisture fully encapsulated or resinous is, at least in the area provided with connecting lugs Connection electrodes in a very complex process sealing with a one-component thermoset.

Finally, it is also known from DE 197 54 158 A1, one temperature-dependent switch completely with a shrink cap to surround, from which the connecting strands protrude. The slipped-on shrink cap is hot pressed or glued.

The cost of the various post-treatments described so far of pre-assembled switches are in the Range of 5% of total manufacturing costs, with using shrink caps may even cost these costs are even higher.

One disadvantage of such sealing methods is that this changes the geometry of the switches, they become more voluminous and bulky, with the shrink caps too sharp edges and corners can arise. This is particularly so disadvantageous when wrapping in windings, because on the one hand much more space is needed than the volume of the actual one Switch corresponds, and on the other hand the danger of There is damage to the winding wires. If necessary, must in the known methods, the geometry of the switch also be specifically designed for the subsequent resinification in order to create a corresponding contact surface for the resins. Dipping processes are also known here in which the Switch completely into an immersion bath with sheathing material to be immersed; although the immersion is technologically easier is then a disadvantage that the so covered Switches require a longer drying time. With an epoxy coating after soldering the strands there is also Danger that the inevitable manipulation of the Strands when the switch is installed the sheathing cracks, so that there is a leak and e.g. but drinking lacquer can penetrate.

Against this background, the present invention Task based on a temperature-dependent switch from the type mentioned with a reliable, simple and to provide inexpensive sealing.

In the case of the switch mentioned at the outset, this does this solved that a stamped in the area of the interface and this sealing adhesive layer is provided.

• Einlegen des Schaltwerkes in ein Unterteil des Gehäuses,
• Verschließen des Unterteiles mit einem Deckelteil unter Ausbildung zumindest einer Nahtstelle,
• Aufstempeln einer Kleberschicht im Bereich der Nahtstelle, um die Nahtstelle abzudichten, und
• Aushärtenlassen der Kleberschicht.

In a method for producing such a temperature-dependent switch, which has a temperature-dependent switching mechanism accommodated in a housing and which, depending on its temperature, produces an electrically conductive connection between at least two connection electrodes arranged on the outside of the housing, the following steps are accordingly carried out:

• Insert the rear derailleur into a lower part of the housing,
• Closing the lower part with a cover part to form at least one interface,
• Stamping an adhesive layer in the area of the seam to seal the seam, and
• Allow the adhesive layer to harden.

The object underlying the invention is achieved in this way completely solved.

The inventor of the present application has recognized that that it is surprisingly possible to use glue in the area of Stamp the interface on the temperature-dependent switch and in this way for a very good seal of the seam to care. The stamp process only makes one very Small amount of adhesive targeted only in the area of the seam printed so that the connection electrodes for a subsequent Connecting leads remain free on which then can be manipulated when installing the switch without the Sealing can be damaged.

Surprisingly, the invention goes exactly the opposite Way as described in the prior art. Because semi-finished products are sealed, so to speak, before the assembly with the desired connection technology he follows. On the one hand, this saves a lot of time, because there is no longer a need for those with strands or other supply switches are sealed, but also existing switches in production machines all that is required is a further station in which the semi-finished products be stamped with glue, which is then used for sealing that provides at least one interface.

With the new switch and the new process is further from Advantage that only so little adhesive is applied to the switch is that its dimensions practically do not change. About that Another advantage is that the switches are manufactured very inexpensively can be. As part of the production can namely The usual cycle of the manufacturing machine made the seals so that now - if requested by the manufacturer becomes reliable - all temperature-dependent switches can be sealed regardless of whether these switches actually need this seal later in use. The switches sealed in this way can then be semi-finished be put in stock and depending on the requirements of the Customer with strands or other supply lines. This not only simplifies storage, There are also advantages in sales.

Overall, the new switch is not only more economical, it is also faster to manufacture and more technically reliable.

In a further development, it is preferred with the new method if the switch before stamping the adhesive layer heated and further preferably after stamping the adhesive layer is heated to harden the adhesive layer.

Heating the switch before stamping the adhesive layer has the advantage that the adhesive on contact, so to speak becomes less viscous with the switch, making it easier to get into the Interface runs into it. Hardening can take place alongside heating also done by irradiation with infrared or UV light. Has a separate curing section in the manufacturing machine the advantage that the adhesive hardens quickly and in a defined manner, before being uncontrolled on or in the temperature dependent Switch runs.

It is further preferred if the adhesive layer is stamped is applied, which is when pressed on the switch elastically deformed, the stamp preferably being such deformed that he picked up the adhesive on his face presses into the interface.

Due to the preferably asymmetrical elastic deformation or Deformation of the stamp is easily adapted to the Cross-sectional geometry of the switch, so that the adhesive in the target area can be safely applied. If at the same time it is ensured that the stamp the adhesive into the seam presses, a pumping effect is achieved that for a very safe application of the adhesive in the area of the seam provides.

Of course it is possible to have a temperature dependent Switch in a single operation with a stamp from edit at the top and with a stamp from below so that different Apply glue to seams in one step before gluing in the next step is cured.

It is further preferred if the adhesive layer with a Stamp is applied, the one in its circumference and / or Has cross-sectional contour adapted to the interface end face.

The advantage here is that with a single stamp, so to speak a closed seam adapted to the seam can be provided with adhesive so that there are no starting points there, where in a second working process again Glue must be applied.

It is further preferred if the stamp is used to hold adhesive with its end face immersed in a storage container which is preferably a doctor blade, which is before immersion the stamp is filled with adhesive at a defined height.

The advantage of this measure is that always the same amount of glue taken from the doctor plate and on the temperature-dependent Switch is given so that the amount of glue is sufficient is well defined.

Such transfer of adhesive is different Field of technology known in a similar manner. Here is the SMD technology, in which small components the surface of a board can be glued on. This glue is smoothed out in a storage bed so that it is about has a layer thickness of 200 to 300 microns. A metal stamp is then dipped into the adhesive bed and takes off when pulled out about half of the adhesive thickness. When pressing the Metal stamp on the substrate remains there in turn Stick half of the glue. In contrast to the known method however, the new process becomes more elastic Stamp used, the amount of adhesive defined in the area a seam is given, which is thereby sealed.

Finally, it is still preferred if after curing the Adhesive layer leads connected to the connection electrodes become.

As already mentioned, the advantage here is that initially all Manufacturing steps on the temperature-dependent switch themselves can be carried out before the connection technology takes place, for example, at the manufacturer of engines, Pumping or the like can be done so that reliable sealed temperature-dependent switches in the form of semi-finished products be provided by the invention.

With the new switch, it is still preferred if it is after the new process is established.

Further advantages result from the description and the attached one Drawing.

It is understood that the above and those below Features to be explained not only in each case specified combination, but also in other combinations or can be used alone, without the scope of to leave the present invention.

Fig. 1

den neuen Schalter in einer schematischen Schnittdarstellung von der Seite;

Fig. 2

in einem weiteren Ausführungsbeispiel einen neuen Schalter im vergrößerten Ausschnitt im Bereich der Nahtstelle; und

Fig. 3

in einer schematischen Draufsicht einen Ausschnitt einer Vorrichtung zur Herstellung des neuen Schalters.

The invention is illustrated in the drawing and is explained in more detail in the following description. Show it:

Fig. 1

the new switch in a schematic sectional view from the side;

Fig. 2

in a further embodiment, a new switch in the enlarged section in the area of the interface; and

Fig. 3

in a schematic plan view a section of a device for producing the new switch.

In Fig. 1, 10 denotes a temperature-dependent switch, which has a housing 12 in which a temperature-dependent Rear derailleur 13 is arranged.

A lower part 14 of the housing 12 is electrically conductive Bottom electrode 15 provided, from the side the lower part 14 made of insulating material has a connecting electrode 16 extends out. Furthermore, a cover part 17 is made Metal provided on which a connecting electrode 18 in one piece is provided.

The temperature-dependent switching mechanism arranged in the lower part 14 13 comprises a spring washer 21, which with its edge 22nd supported on the inside of the cover part 17. The spring washer is centered 21 a movable contact 23, which in the in Fig. 1 shown switching position with the bottom electrode 15 in Facility is. In this way, the spring washer 21 electrically conductive connection from the connection electrode 18 via the cover part 17, the movable contact 23 and the Bottom electrode 15 to the connection electrode 16 ago.

About the movable contact 23 is a bimetallic snap disk 24 put over, in the switching position shown in Fig. 1 is free of forces. When the temperature of the switch 10 and thus the bimetallic snap disk 24 above its response temperature raised, the bimetallic snap disc works 24 from the convex shape shown to a concave shape, in its edge 25 on an insulating region 26 of the lower part 14 supports and the movable contact 23 against the Force of the spring washer 21 lifts off the bottom electrode 15. On this way, when the response temperature is exceeded Bimetallic snap disk 24 the electrical connection between the two connection electrodes 16, 18 interrupted. If the temperature drops again, the bimetallic snap disc works 24 back to its position shown in FIG. 1, so that the connection between connection electrodes 16 and 18th is restored.

The cover part 17 is encircled by one indicated at 28 Edge of the lower part 14 firmly connected to this. The circulating Edge 28 is from a high standing by hot pressing Edge of the lower part 14 emerged, as shown in the DE 196 09 310 A1 mentioned in the introduction is described in more detail is.

At 29 in Fig. 1, the transition between the edge is enlarged 28 and the cover part 17 are shown. In detail view 29 it can be seen that between the cover part 17 and the edge 28 forms a seam 31 which has the shape of a cross section has lying V. This interface 31 is now according to the invention sealed or sealed with an adhesive layer 32, so that neither moisture nor dust in the temperature-dependent Switch 10 can penetrate.

Like the adhesive layer 32 on the temperature-dependent switch 10 is stamped, is now in connection with Fig. 2nd discussed where in a further enlarged view of the detail 29 shows an embodiment in which both the lower part 14 and the cover part 17 are made of metal are. To ensure adequate electrical insulation between Providing lower part 14 and cover part 17 is an insulating layer 34 provided, as for example from the beginning mentioned DE 196 23 570 A1 is known, for sealing Kapton film was used.

To seal the interface 31, the one shown in FIG Adhesive layer 32 now using a stamp 35 stamped on the cover part 17 in the area of the interface 31.

The one shown in cross-section is a closed, circular one End face 36 having stamp 35 bears on this Face 36 a small amount of adhesive 37. Like the stamp 35 absorbing this amount of glue 37 is related below explained with Fig. 3.

The end face 36 goes into an edge 38 also circumferential slope 39 over, so that the stamp 35 in such as a cross-sectional contour and a circular end face 36, that is to say the peripheral contour, has like the cover part 17.

The stamp 35 is now on the cover part 17 in the area of flat top 41 next to the seam 31 is moved to first the edge 38 with one on the flat top 41 adjoining inclined surface 42 of the cover part in contact comes. When pressing on the stamp 35, which is made of elastic Material such as rubber is deformed the edge 38 so that the asymmetrically deforming Stamp 35 adapts to the interface 31 and the adhesive 37 is pumped into the interface 31, so to speak. The way, which the edge 38 travels when the stamp 35 is pressed on, is indicated by a dashed line 43.

After in this way the adhesive 37 on the temperature-dependent Switch 10 has been stamped, the stamp 35 withdrawn, with most of the adhesive 37 on the Switch 10 remains. The surface properties are included chosen so that the adhesion between the adhesive 37 and the End face 36 at least not larger, but preferably smaller than the adhesion between the adhesive 37 and the top 41 of the cover part 17.

Any epoxy resin can be used as an adhesive preferably a two-component adhesive is used.

In Fig. 3, a device 51 is now shown in detail, can be produced with the temperature-dependent switch 10.

The switches 10 are on a band 52 in the direction of an arrow 53 clocked through the device 51. You come upstairs for example from the station in which the peripheral edge 28 was hot stamped or flanged.

Next, they go through a warm-up station indicated at 54, in which it is heated to such a temperature be that the adhesive becomes thinner and easily into the Interface 31 runs into it.

A stamping station 55 is connected to the warm-up station 54 in which a carriage 56 is provided, on which at least one Stamp 35 is arranged. Of course it is possible to arrange several stamps 35 side by side on the carriage 56, so that several temperature-dependent switches 10, which also act as temperature monitors be referred to in a single step can be sealed.

In front of the carriage 56 there is a doctor plate 57, above which a Doctor blade 58 is arranged.

A heating station 59 connects to the stamp station 55, in which the temperature monitor 10 on the to harden the adhesive required temperature to be heated. This can by UV radiation, IR radiation or contact heating.

At 61 it is also indicated how the carriage 56 in the stamp station 55 can be moved.

In the following it is assumed that the carriage 56 in the in Fig. 3rd shown position, in which the stamp 35 its adhesive has given to a temperature-dependent switch 10. The the amount of adhesive 37 removed from the doctor plate 57 is now in the Doctor blade 57 supplied, which is set into rotation for this purpose, as indicated at 62. about the squeegee 58 ensured that in the doctor plate 57 a uniformly high Layer of adhesive 37 is present.

The carriage 56 is now moved to the left in FIG. 3, so that the stamp 35 comes to rest on the doctor plate 57, the Rotation is now stopped so that it stops. The Stamp 35 is now immersed in the adhesive 37 and again, whereby he with his end face 36 a defined amount of adhesive 37 extracts. Then the carriage 56 is moved to the right in FIG. 3, so that the punch 35 the position shown in Fig. 2 takes over a temperature-dependent switch 10. Now the stamp 35 is moved to the switch 10 so that the Adhesive 37 comes into contact with the preheated switch 10. The adhesive flows supported by the elasticity of the stamp 35 caused pumping movement into the seam into where it remains even when the punch 35 is withdrawn becomes.

By clocking the tape 52 along the arrow 53, it arrives in this way with adhesive 37 printed switch 10 in the heating station 59, where the adhesive 37 is cured in a defined manner.

Then the temperature-dependent switch 10 is a semi-finished product completed, he can now either in a next one Work step can be provided with leads, or else stored or distributed to processing companies.

Claims (11)

Method for producing a temperature-dependent switch (10) which has a temperature-dependent switching mechanism (13) accommodated in a housing (12) and which, depending on its temperature, has an electrically conductive connection between at least two connection electrodes (16) arranged on the outside of the housing (12) , 18), with the steps: Inserting the switching mechanism (13) into a lower part (14) of the housing (12), Closing the lower part (14) with a cover part (17), forming at least one interface (31), Stamping an adhesive layer (32) in the area of the seam (31) to seal the seam (31), and Allowing the adhesive layer (32) to harden. Method according to Claim 1, characterized in that the switch (10) is heated before the adhesive layer (32) is stamped on. Method according to claim 1 or 2, characterized in that the switch (10) is heated after the adhesive layer (32) has been stamped on. Method according to one of claims 1 to 3, characterized in that the adhesive layer (32) is applied with a stamp (35) which deforms elastically and preferably asymmetrically when pressed onto the switch (10). Method according to claim 4, characterized in that the stamp (35) deforms in such a way that it presses the adhesive (37) picked up on its end face (36) into the seam (31). Method according to one of Claims 1 to 5, characterized in that the adhesive layer (32) is applied with a stamp (35) which has an end face (36) which is contoured to the seam (31). Method according to one of Claims 4 to 6, characterized in that the end face (36) of the stamp (35) for receiving adhesive (37) is immersed in a storage container. Method according to claim 7, characterized in that the storage container is a doctor blade (57) which is filled with adhesive (37) at a defined height before the plunger (35) is immersed. Method according to one of Claims 1 to 8, characterized in that, after the adhesive layer (32) has hardened, feed lines are connected to the connection electrodes (16, 18). Temperature-dependent switch with a temperature-dependent switching mechanism (13) accommodated in a housing (12), which, depending on its temperature, creates an electrically conductive connection between at least two connection electrodes (16, 18) provided on the outside of the housing (12), the housing ( 12) has a lower part (14) and a cover part (17) which closes this to form at least one seam (31),
characterized in that an adhesive layer (32) stamped in the area of the seam (31) and sealing it is provided. Temperature-dependent switch according to claim 10 according to the method of one of claims 1 to 9.

Images