EP0677855B1 - Resistor - Google Patents

Abstract

In order to manufacture completely ready-made (that is to say provided with connecting wires) self-stabilising resistors having PTC elements as active parts, such as those resistors especially on coil windings, such as those used by electric motors, the invention provides a method according to which bearing surfaces and covering surfaces for the PTC elements are stamped out on a metallic supporting strip, a PTC element is placed on each bearing surface and is attached, the covering surface being bent over the PTC element, the bearing surfaces and covering surfaces being provided with connecting wires, and the covering surfaces and bearing surfaces being separated from the remaining supporting strip.

Description

The present invention relates to a resistor, in particular for use on coil windings e.g. Electric motors, with at least one flat PTC element, on the opposite one Face plates are soldered, which the PTC element have outstanding approaches.

Such a resistor is known from DE-A-37 03 465.

With the known resistance, the outstanding contact parts open in an area for connecting terminals, to which connecting wires, if necessary are to be connected. This is usually done manually and is time consuming.

For monitoring electrical devices, such as in particular for monitoring coil windings on e.g. Electric motors or similar devices are so-called self-stabilizing Resistors used, which have PTC elements, with which electrical leads are connected. The resistances be in close thermal contact with the electrical device, so For example, brought the coil. To monitor temperature changes over a to be able to determine a larger area of the coil such resistors are provided in series and on different places of the winding attached. Usually are the connection wires directly with the PTC elements soldered to this, with a solderable metallic contact surface, e.g. an evaporated silver coating are.

The connecting wires are usually soldered by hand. This is expensive, especially when extremely small PTC elements be used, the heights of less than 2 mm and Diameters from less than 5 mm to only 3 mm exhibit. Further assembly is also done by hand, Shrink sleeves are e.g. handmade.

For the reasons mentioned above, the manufacturing costs for such resistances significantly.

The invention is therefore based on the object of a resistor of the type mentioned at the beginning to create the inexpensive is, in particular the assembly with connecting wires should be facilitated.

According to the invention, this object is achieved in the aforementioned Resistance is solved by attaching the PTC element electrically connected connecting wires are attached, which are held by curved edges of the lugs.

Fastening is preferred by the measure mentioned Welding the connecting wires to the metal plates, which in the others are also referred to as support and cover surfaces, facilitated. Around the connection wires before the fixed connection to be positioned with the support and top surface at their bases, the edges of the lugs are bent perpendicular to them.

With the invention is a largely automated and thus mechanical manufacture of such assembled self-stabilizing Resistance allows, which increases the use of manual labor can be reduced or almost eliminated.

It is preferred if the PTC element is sandwich-like enclosing sheet metal plates formed substantially circular are and the approaches tangential from the sheet metal stand out. The approaches are advantageously at the Sheet metal plates offset from each other, but extend parallel towards each other away from the metal plates.

It can also be provided that the attached Connection wires are taped so that the ready-made Resistance to further processing are promoted can. This further processing can e.g. consist in that the resistors are provided with an insulation layer, which can be made by powder coating. Furthermore, a shrink sleeve can be pushed on or shrunk on will.

In addition, series connections of two or more can be used PTC elements can be provided. With a series connection of To this end, two PTC elements have one end of a piece of wire the top surface of the first PTC element connected during the other end of the piece of wire with the contact surface of the immediate following PTC element is connected. The contact surface of the first PTC element and the top surface of the second PTC element is provided with the connecting wires. With three in a row switched PTC elements is the first end of each Connection wire with the top surface of the preceding PTC element and the second end of the lead wire with the immediately following PTC element connected, the bearing surface of the first PTC element and the top surface of the third PTC element is provided with individual connecting wires.

Fig. 1

eine schematische Darstellung der ersten Arbeitsschritte eines Verfahrens zur Herstellung des neuen Widerstandes, wobei Fig. la eine Seitenansicht auf den Eintauchvorgang eines Trägerbandes darstellt;

Fig. 2a und b

Ansichten auf ein PTC-Element mit Auflage- und Deckfläche, vor dem Abtrennen der Deckfläche von dem Trägerband;

Fig. 3

weitere Verfahrensschritte für die Konfektionierung des neuen Widerstandes; und

Fig. 4

die Endkonfektionierung des neuen Widerstandes.

Further advantages and features of the invention result from the claims and the following description, in which an embodiment of the invention is explained in detail with reference to the drawing. It shows:

Fig. 1

is a schematic representation of the first steps of a method for producing the new resistor, wherein Fig la shows a side view of the immersion process of a carrier tape;

2a and b

Views of a PTC element with support and cover surface, before the cover surface is separated from the carrier tape;

Fig. 3

further procedural steps for the assembly of the new resistor; and

Fig. 4

the final assembly of the new resistor.

In the following description the new resistance is used a process for the manufacture of assembled, self-stabilizing Resistors described. This procedure starts from an endless carrier tape 1 made of thin sheet metal.

Support surfaces 2 and cover surfaces 3 become from the carrier tape punched out for PTC elements 4, which continue to be narrow Holding strip 6 over this extending connecting sections 7, 8 are held (method step A). The cover and support surface 2, 3 extend essentially tangential approaches 9, 11 for later recording and definition of connecting wires.

6 openings 12 are punched out of the holding strip, about which in the further processing an exact Positioning of the holding strip 6 and thus also the deck and Contact surfaces 2, 3 can be effected.

Then embossing takes place from the plane of the carrier tape 1 out (step B). On the one hand, edges 13 (FIGS. 2a, b) the approaches 9, 11 in the top view of Figure 1 upwards bent. On the other hand, the top surface 3 becomes approximately as wide the plane of the carrier tape 1, but still parallel to this lying offset, as it corresponds to the strength of the PTC element 4. Deck and support surface 2, 3 can continue to plate or be bowl-shaped, as shown in Figure 2b can be removed, so that edges 14 are formed, the enclose and center the PTC element 4 around its circumference can.

In a further step C is on the support and top surface 2, 3 Lot 16 applied.

Then the soldered contact surface is applied PTC element in the form of a PTC pill. The PTC elements can be fed on a vibrating pot 17 and either from taken over by a gripper and placed on the support surface 2 be, or by means of a slide and an exposed Stop the support surfaces 2 are fed. For positioning of the PTC elements 4 can, in addition to the contact surface 2 Positioning pins 18 can be provided which, if a renewed Contact surface 2 comes into its area, can be moved upwards and record the PTC element 4 between them. Subsequently in step E, the tab 7 carrying the top surface 3 becomes such bent that the top surface 3 exactly over the PTC element 4th brought. The result of this step is in the figures 2a and b in plan view and in side view shown enlarged. In step F below, a Soldering of PTC element 4 and support and top surface 2, 3 with the previously applied solder 16. The soldering takes place preferably with high frequency, ie by means of a high frequency generator. After fastening the PTC element in this way 4 on the contact surface 2 and thus also fixing the top surface 3 over the PTC element 4 can the carrier tab 7 are separated from the carrier tape 6, for example with the 19 indicated place (Figure 2b). This takes place in the procedural step G. Then there are support surface 2 with carrier tape 6 and top surface 3 are electrically separated from one another, that is, they form no short-circuit connection anymore. The quality of the PTC element to check, the carrier tape 6 is now on rollers 21st (Fig. La) to test the resistance at a given temperature deflected into an oil bath 22 and the resistance is via contact pins 23, which are driven against the connecting lugs 9, 11, checked. In step I below, degreasing and finally (step J) cutting off defective PTC elements, the defectiveness in the above Test process was determined.

Then approaches 9, 11 are provided with appropriate ones Connection wires 23, 24 (Figure 3). If multiple PTC elements 4 should be interconnected in series, for example two PTC elements in a twin circuit or three PTC elements in a triplet, so like this in Figure 3 is shown, the connection ends 26, 27 of a U-shaped bent wire 23 on the one hand with the approach 11 of the cover part 3 of a PTC element (end 27) and the other (end 26) with the approach 9 of the support part 2 connected. The wire ends 26, 27 are preferably welded to the lugs 9, 11 (Step K1). In step K1 'it can be seen how three successive ones PTC elements thanks to two U-shaped connecting wires can be connected in series with each other. In step K2 are the individual leads 24 on the free approaches 9 or 11 attached. The connecting wires 23 become like this prepared by being pulled off a wire roll, initially at a front end in a stripping block 28 a sufficient The front wire is stripped, then the wire along two aligned pivotable relative to each other Grippers 29 are promoted. After reaching the required wire length, the wire piece 23 of the The remaining wire was cut off and also one at the rearward end 26 Stripped. The grippers 29 pivot against each other and bend the piece of wire 23 into that at the beginning of the figure 3 shown U-shape, at the beginning 27 and end 26 of the wire get into the parallel alignment shown.

After attaching the lead wires 23, 24, these are preferred taped, for example between two adhesive tapes bordered, which can be done in a conventional manner (step L). Then after the lead wires 23, 24 and over this the PTC elements can be held by the straps 31, the PTC elements are completely separated from the carrier tape 6, by complete separation at 32 (Figure 2) (Step M).

The self-stabilizing resistors produced in this way can now be used for further processing steps.

A coating can take place, for example casting or a powder coating. In the latter case in process step N, the initially conveyed horizontally Resistors 33 pivoted through 90 °, so that the connecting wires point upwards. This happens because the belt 31st between rollers 34, 36 provided in pairs, which are perpendicular stand to each other, is led through. The resistors 33 are guided through a powder bath. The sticking powder will then by heat generated by a radiator 37 can be melted, cools down again and forms one dense coating (step O). Finally, about that Resistors 33 still a shrink cap 38 are pushed. This is separated from an endless hose 39 (step P), possibly closed in its free end and with a Provide identification (step Q). You can do this on one Kreisförderer 39 are promoted. Then it becomes easy pushed onto the self-stabilizing resistors 33 (Step R), whereupon in step S finally one Can connect shrinking process so that the shrink cap 38th the resistor 33 tightly enveloped. Finally, they can Lead wires 23, 24 are shortened.

Claims (9)

1. Resistor (33), particularly for use on coil windings of e.g. electric motors, comprising at least one flat PTC-element (4) having two opposing front faces whereupon sheet metal laminas (2, 3) are soldered that comprise lugs (9, 11) protruding the PTC-element (4), characterized in that leads (23, 24) electrically connected to the PTC-element (4) are fastened to the lugs (9, 11) and held by bent edges (13) of the lugs (9, 11).
2. Resistor (33) of claim 1, characterized in that the leads (23, 24) are welded to the lugs (9, 11).
3. Resistor (33) of claim 1 or two, characterized in that the laminas (2, 3) enclosing the PTC-element (4) like a sandwich are formed substantially circular and that the lugs (9, 11) extend tangentially from the laminas (2, 3).
4. Resistor of any of claims 1 through 3, characterized in that the lugs (9, 11) are arranged at said two laminas (2, 3) offset with respect to each other and extend away from said laminas (2, 3) parallel to each other.
5. Resistor of any of claims 1 through 4, characterized in that it comprises a series connection of two PTC-elements (4), whereby one end (26) of a piece of wire is connected with the top surface (3) of the first PTC-element (4) and the other end (27) of the piece of wire is connected with the bearing surface (2) of the next following PTC-element (4), whereby the bearing surface (2) of the first PTC-element (4) and the top surface (3) of the second PTC-element (4) are provided with said leads (23, 24).
6. Resistor of any of claims 1 through 5, characterized in that at least three PTC-elements (4) are connected in series, whereby each first end (26) of a lead is connected with the top surface (3) of an immediately preceding PTC-element (4) and each second end (27) of the wire is connected with the bearing surface (2) of the subsequently following PTC-element (4), the bearing surface (2) of the first PTC-element (4) and the top surface (3) of the third PTC-element (4) being provided with the leads (23, 24).
7. Resistor of any of claims 1 through 6, characterized in that the fixed leads (23, 24) are connected to a belt.
8. Resistor of any of claims 1 through 7, characterized in that it is provided with an insulating layer, preferably with a powder coating.
9. Resistor of any of claims 1 through 8, characterized in that a shrink-on sleeve (38, 39) is engaged and shrunk on the PTC-elements (4) connected to the bearing and top surface (2, 3) and provided with leads (23, 24).

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