DE2911950A1 - THERMAL FUSES AND MANUFACTURING PROCESSES FOR IT - Google Patents

Description

-, " ⁴ ^ Case 66, 58-70

Littelfuse, Inc., 800 East Northwest Highway, De? - Piaines,

Illionois 60016 (V. St. A.)

Thermal fuses and manufacturing processes therefor

Thermal fuses and manufacturing processes therefor

The invention relates to thermal fuses and normally Open switches of the type that responds to the ambient temperature when this reaches a certain trigger value achieved. Normally closed embodiments of such thermal fuses are z. B. often in the windings of electric motors and other devices that require thermal protection, built in and thus connected in series, so that the fuse the device concerned switches off if the ambient temperature exceeds a certain safety level.

Thermal fuses that respond to the ambient heat are produced in two different embodiments (See, for example, US Pat. No. 3,180,958 on the one hand and US Pat. No. 3,944,960 on the other hand). Both types of fuse will the environment wall inside the fuse by essentially »::! iän ^ i 'ciiiiö, cylindrical electrically conductive device

• 09 * 41/0644

-yf-

transferred housing that is essentially closed at one end and is open at the other end. A first lead extends longitudinally into an insulating seal in the open end of the housing and terminates in a flat end piece that forms a separable contact interface with a spring metal connector produces, which is pressed by spring force against the end piece and has several contact legs that are resilient Press against the conductive inner walls of the housing and are thus in sliding contact. A second lead extends in. Longitudinal direction in the closed housing part, in which they are seen through or otherwise with the housing end wall is connected so that a permanent inseparable low-resistance connection is formed with the end wall. The interface between the contact leg of the connector and the inner walls of the housing and the interface between the first supply line and the connector form two separable electrical contacts between the leads, the resistance of which is considerably greater than that between the second lead and the housing end wall. It is assumed that at high rated currents large electric motors or other devices that require thermal protection generate heat at these separable contact interfaces which can strongly influence the ambient temperature at which the fuse is opened and thus lower it.

In the thermal fuse according to the first-mentioned US-PS, the housing contains a composite body consisting of a plate made of fusible material at the closed end of the housing, a first, partially compressed spring, the connector carrying the contact leg, which is guided against the end of the insulated housing end through the open Lead, and a second, weaker and partially compressed spring on the opposite side of the connector which applies a force to the connector in a direction that tends to move the connector away from the lead. ^ QX) Xi the platelet melts at the trigger temperature,

• 0 * 041/0644

- Ijf-

ISSO

the stronger 'spring' relaxes, until its force equals that of that the weaker leather is, and then the originally weaker peder relaxes and pushes the connector away from the end of the adjacent supply line, so that the fuse is opened.

In the thermal fuse according to the second-mentioned US-PS, in which deformable contacts are separated from an adjacent contact surface by a leg deformation member (in a manner corresponding to US Pat. No. 3,274,363 or 4,109,229), the composite body in the housing comprises just a single partially compressed each. This applies pressure to a fusible plate, which in turn is arranged adjacent to a leg deformation member which, when the plate melts, is pressed against the contact legs of the connector and deforms the legs inwardly away from the interior of the housing, so that the fuse is opened. In the case of the fuse types according to the US patents mentioned above, the structure is such that the resistance value of the explained contact interfaces cannot be adjusted during or after assembly, and differences in the internal resistance of apparently identical fuses can result in changes in the ambient temperature, in which identical fuses are opened. Furthermore, the deformable contacts of these fuses are made of Pedermetal, and the contact resistances between the contact legs and the adjacent contact surfaces are much higher than desired and can increase undesirably with the ambient temperature and with the heat generated by electricity at the contact interface. Premature opening of the fuses below the target temperature due to the platelets creeping is also a special problem, e.g. B. in the fuse according to US Pat. No. 3,944,960, since such creeping can apply a contact opening force to the contact legs, namely due to the position of the plate in the vicinity of the contact legs.

- / Ίο-

Another disadvantage of the thermal fuse according to US Pat. No. 3,944,960 arises due to the position of the fusible Plate between the leg deformation member and the contact legs of the connector. This will when the platelet melts, the initial relaxation of the spring is used to move the leg deformation member by an amount which is approximately equal to the original thickness of the plate before the force of the spring deforms the contact legs causes; thus the required, initially greater force of the spring causes the platelet to creep instead an opening of the fuse, therefore a stronger spring is required to deform the ones resting against the housing walls Contact leg to generate required force, whereby in turn, the creep problem is exacerbated. ,

The object of the invention is to provide a through the ambient temperature actuatable or thermal fuse or a circuit breaker of the type that has a cylindrical housing and contact legs resting on the housing for producing a Has continuity between the leads and the fuse, which is designed so that the internal resistance of the fuse in with respect to previous fuses of this type can be reduced considerably, so that the generated inside the fuse Heat is kept low.

A thermal fuse and a manufacturing process should be used be created for this, the tripping temperature of the fuse especially in the case of higher currents within narrower Tolerances can be maintained than is the case with the known fuses. When securing according to the invention the internal resistance is intended to be adjustable in a simple manner to a desired low value during the assembly of the fuse and remain at or near this set value for the entire operating time of the fuse. The backup according to the invention is intended to be inexpensive in mass production

909041 / 06U

be producible. It is also provided that the leg deformation member is acted upon by spring force and that when the melting plate melts, the relaxation of the spring, the the leg deformation member presses against the contact legs, immediately causes deformation of the contact legs.

When the fuse according to the invention is closed, there is one, preferably two, contact legs on an associated one Contact surface, and the fuse is opened by that the contact legs are deformed away from the contact surface and thereby the fuse is opened. The fuse can be triggered by the ambient heat, i. H. it is a thermal one Fuse, and it is designed so that it absorbs the ambient heat in an effective manner, with the contact legs on the abut conductive inner surface of a cylindrical housing containing a composite body between a conductive Housing end wall, on which a fusible plate forms an element of this composite body, and the opposite, initially open end of the housing is located; this end is closed by an insulating seal. Two feed lines run preferentially in the longitudinal direction in the opposite housing ends, one feed line by pressing or otherwise is inextricably connected to the conductive end wall and the other lead penetrates the insulating closure.

In the fuse according to the invention, the last-mentioned supply line are and the deformable contact legs a single solid body made of a relatively soft material with low resistance, z. B, made of silver-plated copper, so that only a very low-resistance, separable contact interface between the leads consists; thus the fuse is designed with a minimal internal resistance, so that the generated inside Heat is kept low. (This solid-state or monolithic structure is in contrast to the spot-welded one Connection between the spring metal contact legs

909S41 / 06U

2 J 1 1950

and the supply line of US Pat. No. 4,109,229.) For this purpose, one or more contact legs that rest on the housing are designed as a one-piece part of one supply line, so that between the contact legs and the associated supply line there is no contact interface. Although not strictly necessary, there is a preferred education the invention, the lead and the contact legs made of a relatively soft material with a low resistance value, z. B. silver-plated copper, which is slightly deformed when pressed against the curved inner surfaces of the housing and thereby the contact area is enlarged so that the contact resistance is kept small. (Spring metal materials used in State of the art for making connector legs are used, have a much higher natural resistance and generally do not deform that way as strong as a softer material under the influence of pressure, so that the contact area is not increased to the same extent.) The composite body, which also contains the aforementioned melting platelet, comprises a leg deformation member and a spring, which acts on the leg deformation member in a direction towards the contact legs, so that when the melted Plate, the leg deformation member deforms the contact legs away from the housing walls.

In a further embodiment of the invention, the contact legs into a low-ohmic contact with the housing walls other means than their spring property pressed. For this purpose, the contact legs, which are preferably jiach laterally are inclined on the outside of the end portion of the associated supply line, against a support element which is part of the composite body, printed so that the contact legs to the outside against the housing be spread. Over a range of pressures acting on the support element, it was determined that the Contact resistance between the contact legs and the housing changes. As a result, when assembling the fuse,

903841/0644

after the composite body has been introduced into the open housing end and before the open housing end with an insulating seal is closed, the lead from which the contact legs extend inwardly against the support element with a gradually increasing force printed until the measured contact resistance falls between the feed lines to a predetermined target value (e.g. 0.9 m-ft), the measurement at probe connection points of the supply lines, which have a distance of approx. 38 mm. When the contact resistance reaches this value, the supply line is fixed in its set position. The force of the support element acting against the contact legs generally causes a lower contact resistance with the housing wall than is caused by the force a resilient contact leg alone, which is not supported by other forces, is possible.

In order to prevent a shift in the position of the support element in the event of creep of the melting platelet, further comprise Ausgestaltvng the invention the spring elements in the composite body in the fuse housing a relatively weak, long, fully compressed spring and a relatively strong, short, partially compressed spring. The short, strong one partially compressed spring is positioned on the side of the support member opposite to the side on which the leg deformation member and the relatively weak, long, fully compressed spring are arranged. The partially Compressed spring keeps the relatively weak spring fully compressed and eliminates any play in it the connector in the housing. The one having the contact legs The feed line preferably runs through the relatively weak, fully compressed spring and into the leg deformation member, wherein the outwardly extending contact legs of the supply line to the outside through openings in the leg deformation member pass without exerting pressure on them and make contact with the edge portion of the support member,

909841/0644

its position remains the same as long as the relatively weak spring is completely compressed. Any creeping of the Melting plate, which is preferably between the partially compressed strong spring and the closed end of the housing is set, is compensated by a movement of the last-mentioned spring without any displacement of the support element takes place. When the platelet melts at a certain trigger temperature, a first occurs Relax the strong spring, whereupon the other spring relaxes and immediately the leg deformation member against that Contact leg of the supply line presses, so that this from the housing walls are pushed away. In an advantageous embodiment of the invention, the leg deformation member consists of Insulating material and has a cavity into which the contact legs are completely drawn so that they are related are completely isolated on the housing wall.

In one embodiment of the invention, the closure that closes the initially open housing end is a hardened one Epoxy body that hermetically seals the end of the housing. For this purpose, the one encompassing the deformable contact legs Supply line at one end has one or more recesses into which the epoxy compound flows so that it is in its position around the supply line is set when the initially soft epoxy adhesive hardens as it hardens. The set, the The force acting on the supply line is maintained until the epoxy has cured, as the epoxy insulation seal is the attachment for the lead pressed against the support element. The epoxy is made by inserting the fuse cured in a furnace which is set to a desired temperature which is below the target melting temperature of the melt platelet is heated. The curing process for the epoxy takes several hours. Therefore, fuse holders and the necessary pressurizing agents remain on the fuse while the epoxy cures. In advantageous Embodiment of the invention is therefore provided, a different

909841 / 06U

to apply a simple procedure in which the set, the force acting on the contact leg automatically at the Assembly of a finished closure, d. h, a closure that does not need to be hardened for plague laying on the open housing end is made immutable.

One embodiment of such a closure includes one preferred longitudinally divided compressible elastic body, the supply line having the contact legs, the extends into the fuse housing, first loosely enclosing it. After the lead is pressed against the support member to The outer edges of the initially open housing end are used to generate a desired measured contact resistance pressed around the split closure and press it tightly together around the supply line so that its position in the housing cannot be changed is made and the pressure of the splayed out Contact legs against support element and housing walls as well is made immutable.

A second embodiment of the closure consists of a rigid body, e.g. made of ceramic, with an inner end that is pressed into contact with a preferably laterally protruding section of the lead carrying the contact legs and the contact legs with the desired pressure against the support element presses. This rigid closure is then fixed in position by the housing around the closure end pressed around.

With these two closures, epoxy compound is applied to the connecting lines between the closure, the housing and the first supply line applied to make these portions of the fuse hermetically sealed. Since the lock itself and not the fipoxid the set contact pressure of the fuse cannot be changed, the fuse can be placed in a curing oven, without having to have any special pressure-exerting fasteners,

S09841 / 06U

The invention is explained in more detail, for example, with the aid of the drawing. Show it:

Pig. 1 is a perspective view, enlarged several times, of the thermal fuse according to the invention;

Pig. 2 shows a longitudinal section 2-2 according to Pig. I through the fuse;

Pig. 3 shows a larger cross-section 3-3 according to Pig. 2 by part of the fuse;

Pig. 4 shows a cross section 4-4 through the fuse according to Pig. 2;

Pig. 5 one of the pig. 2 corresponding sectional view after the fuse has been melted;

Pig. 6 is an elevation through an uncompressed hourglass-shaped coil spring shown in FIG Position in the fuse after Pig. 8 is arranged;

Pig. 7 is an end view of the Pig coil spring. 6;

Pig. 8 is a greatly enlarged sectional view of a portion of another embodiment of the fuse shown in FIG similar to Pig. 2, but the conical Peder according to Pig. 2 by the coil spring after Pig. 6 is replaced;

Pig, 9 longitudinal sections through another embodiment

and 10 of the thermal fuse, the Pedern plague body made of elastic-compressible material instead of coil springs according to Pig, 1-4 and the fuse is shown before and after melting;

Pig, 11 an embodiment of the invention which forms a and 12 thermal switch, namely before and, respectively, after exposure to the same with the trigger temperature;

Pig. 13 is a perspective view, enlarged several times, of the fuse according to the invention;

903841/0644

291195Q

14 shows a longitudinal section 14-14 through the fuse after Pig. 13;

15 shows a longitudinal section through the fuse according to FIG. 14 after melting;

16 shows the first step in the assembly of the fuse parts according to FIGS. 13-15, with a Composite body is inserted loosely into the initially open end of the housing;

17 shows the application of a split closure and a lead with a downward force, creating opposed coil springs compressed and contact legs of the supply line in contact with the inner walls of the housing be spread open what measured with an ohmmeter will;

Fig. 18 is a larger sectional view of the top of the fuse of Fig. 17 after the split Closure is squeezed tightly to fit around the supply line by making the upper edge of the housing tight was pressed against the closure to de position of the closure, the supply line and other composite body elements to fix in the housing, and after applying an epoxy sealant to the previously exposed connection points between closure, housing and supply line;

19 shows a horizontal section 19-19 through the closure according to Fig. 18;

Fig. 20 is a plan view of the end portion of a long Wire strand from which the leads with the integral contact legs for the Fuses are formed according to FIGS. 22-25;

FIG. 21 shows the first step in the formation of a lead element at the end of the wire strand according to FIG. 20; FIG.

22 shows a longitudinal section through a further embodiment of the fuse, which corresponds to that according to the

S09B41 / 06U

Mg. 13-19 is similar, but with the lead and the closure through the lead after Pig. 21 and another design of the lock are replaced;

Mg. 23 the first step in assembling the parts of the fuse according to Mg. 22, whereby a composite body loosely in the initially open · end of the housing is introduced;

Mg. 24 the application of external forces to the closure and the supply line, the opposite Compress coil springs and insert the contact leg of the lead into a desired one Spread open the contact with the inner walls of the housing, measured with an ohmmeter;

Mg, 25 is a larger sectional view of the top of FIG Fuse unit according to Mg. 24, after the lock is pressed tightly around the supply line and the upper edge of the housing was pressed tightly around the closure, so that the position of the closure, to fix the supply line and other composite body elements in the housing, and after application an epoxy sealant on the free connection points between the closure and the housing and supply line.

Hach the Mg. 1-5 includes one that can be triggered by the ambient temperature or thermal fuse 1 a metal housing 2 made of brass with cylindrical walls 2a, which is preferably on the Inside a silver plating with a thickness of approx. 0.005 mm. Originally the housing is open at one end and closed at the other end with an end wall 2b. the End wall 2b has an opening 4 through which a supply line runs. The supply line ends in a larger head end 6a and is upset or pressed on the outside of the housing end wall 2b, so that it forms a tight,

909841/0644

forms a hermetically sealed low-resistance connection. The lead 6 is z, B, a tin-plated copper wire,

The open end of the cylinder wall 2a has a thinner, easily deformable collar 8 with an end section 8a, around the end of a closure disk 11 against a shoulder 9 is bent over at the junction between the thinner collar 8 and the thicker section of the cylinder wall 2a of the housing 2 is formed. The closure 11, which in the practical embodiment is a glass-filled melamine, has an opening 11a through which a supply line IO extends, which extends into the initially open end of the housing 2. The supply line 10 has a fixing recess 12, in the epoxy adhesive or the like, which closes the housing end airtight, runs the supply line 10 at this point against the Housing insulated and firmly anchored in a position to be explained.

In the practical embodiment of the fuse is the feed line 10 a tempered copper wire with a diameter of approx. 1,024 mm (18 gauge) and a tensile strength of

ο
13620-15890 kgf / 6.54 cm, which has a silver coating with a thickness of 0.005 mm. The supply line 10 consists of a copper wire with elongated holes formed in the longitudinal direction (one of which is the elongated hole 15 which completely penetrates the wire according to FIG. 2). The copper wire is then cut laterally along the elongated holes to form individual leads, each of which has an elongated hole open at one end, and the section of each lead on opposite sides of the end section of each elongated hole is bent outwards to form a fork end which forms contact legs 10a. Then the copper lead is silver plated.

The supply line 10 durcnsetzt a spring-loaded Verbundbzw. Laminated body and runs between the closure 11 and

909841/0644

-X-

the end wall 2b of the housing 2. In the rest position of the fuse shown in the figures, the contact legs 10a printed at the inner end of the lead 10 against a support element 13, which the contact legs 10a in contact with the silver-plated cylinder inner wall 2a of the housing spreads or expands. The one used to form the lead 10 Copper wire is a soft, easily deformable copper, so that the contact legs 10a when they are in contact with the silver-coated Inner walls of the housing are spread apart, are low deform and form contact over a certain area that is larger than point contact with the housing (cf. esp. the Pig. 2 and 3), so that an unusually low total contact resistance of z. B. less than 1 m-Ω. ever Security is guaranteed. When assembling the fuse 1 before applying the epoxy adhesive, the contact resistance between the contact legs 10a and the housing walls set to a low set point by increasing the inward pressure of the supply line against the support member 13 is increased until a measured value of this contact resistance reaches the setpoint. While the supply line in this setting is held, the adhesive 14 is applied and cured so that it forms a seal that seals the housing end closes and fixes the supply line in the set position; so the internal resistance of the fuse remains on the once set value.

In addition to the support element 13, which preferably consists of an insulating material such as glass-filled melamine, the composite body comprises a plate 16 made of fusible material which melts at a certain trigger temperature, a metallic pressure distribution disk 18, a relatively short, strong coil spring 20, an insulating leg deformation member 24 and a relatively weak, long coil spring 26. The coil springs 20 and 26 consist, for. B. made of string wire. The plate 16 is between the head 6a of the supply line 6 and the pressure distributor

9098A1 / 06U

disk 18 set. The platelet is thereby preferred formed that a granular mixture of fusible material is compressed or compressed against the closed end of the housing will. This creates a much closer connection between the fusible material and the housing walls, whereby the heat conduction to the platelet is increased. When a self-retaining fusible chip in the open end of the housing If the fuse were to be used during the manufacture of the fuse, the plate would initially have to be slightly smaller than the inner diameter of the housing, which would affect the heat transfer to the plate through the housing walls, if the plate would not be compressed and expanded in close contact with the housing wall. A very soft plate could be compressed in this way, but it would normally not be the same very close contact between Platelets and housing walls can be achieved in the same way as when using a granular material. In addition, platelets are fusible usually relatively inflexible bodies in which, once you see:? small housing of thermal fuses strong compression is very difficult, if not impracticable.

The relatively short, strong, compressed coil spring of FIG. 2 is in a partially compressed state between the Pressure distribution disk 18 and the right side of the support element 13 included. The coil spring 20 is conical, and you wide end acts against the edge portions of the pressure distribution disc 18, It has been found that the pressure of the coil spring 20 on the pressure distribution disk 18 is better distributed over the plate 16 if the wide and not the narrow The end of the helical spring rests against the pressure distribution disk 18. The leg deformation member 24, which is preferably made of a hard ceramic material, has two planar projections 24d on, which act against the left side (in Fig. 2) of the support element. The leg deformation member 24 has a cylindrical

803841/0644

-χ- η ■

see passage 24a, through which the supply line 10 is free extends and which merges into a conical leg-deforming cavity 24 "b, which extends to the end of the link 24 through an outwardly facing opening 24c between the projections 24d opens and further communicates with the exterior of the member 24 through laterally facing openings 24e, the Clearance openings for the contact legs extending outward beyond the limits of the leg deformation member 24 10a form.

The relatively weak long coil spring 26 is completely between the leg deformation member 24 and the closure 11 compressed by the force of the spring 20, which also eliminates any play in the composite body. As the coil spring 26 remains completely compressed at any time before the plate 16 melts, it can be seen that the position of the Support element 13 remains unchangeable, and thus the pressure and the contact resistance between the contact legs remain 10a, which are spread by their contact on the support element 13 against the housing 2, constant even when creeping of the fusible plate 16 takes place.

When the environment in which the fuse is located reaches the target tripping temperature, the lamina 16 melts, see above that first the stronger, conical coil spring 20 relaxes, after which the larger coil spring 26 is completely relaxed and the leg deformation member 24 pushes to the right (in the drawing). The movement of the leg deforming member 24 to the right causes the contact legs to converge 10a in the cavity 24b (cf. Pig. 4). The pressure distribution disk 18 as well as the support element 13 and the leg deformation member 24 are slightly smaller than the internal dimensions of the housing, so that there is play for the molten material is present through the entire fuse (see Pig. 4),

909ÖA1 / 06U

-r-

6-8 show an off-center, hourglass-shaped coil spring 2OA. The helical spring, which preferably consists of string wire, preferably replaces the conical helical spring 20 according to FIG. 2. The coil spring 20A has outer spiral turns 21 and 23, which are the turns with the largest diameter are at opposite ends of the screw, and between these eccentric intermediate turns 25 and 27 with smaller Diameter. As can best be seen from Fig. 8, these various turns of the screw are so eccentric provided that when the spring is compressed, the adjacent sections of the windings partially overlap and one inside the other (see. Fig. 8), so that the length of the compressed spring compared to that of a conventional hourglass-shaped coil spring is reduced. (With a sol- Chen conventional spring, the opposite halves of the coil spring are symmetrical, so that when compressed corresponding turns are aligned with one another and therefore cannot lie one inside the other.) Due to this special training the spring, this can be very small when compressed, but with a creep of the fusible Plate 16 can follow and sufficient force can be maintained to compress the other coil spring 26 completely to keep.

9 and 10 show a preferred embodiment of a normally closed fuse I ¹ , in which the coil springs 20 or 20A and 26 by solid bodies 20 'and 26' made of elastically compressible material, for. B. silicone rubber, are replaced. This embodiment offers the advantage that it requires fewer parts and assembly steps and is therefore more cost-effective to manufacture than the fuse 1 according to FIGS. 1-5. Furthermore, it is easier to assemble with automatic assembly machines, since coil springs, in contrast to solid bodies made of elastically compressible material, are difficult to handle with such machines and to bring into the correct position in the housing. the

$ 09841/0644

The lower number of parts in the fuse I ¹ results from the fact that it requires neither the epoxy adhesive 14 nor the pressure distribution disk 18 of the fuse 1. The plague body 20 'of elastically compressible material has a central opening 20a' which forms a clearance opening for the flow of the platelet material when the platelet melts at the temperature of the fuse. The silicone rubber body 20 'is partially compressed and forms a strong peder element which completely compresses the other silicone rubber body 26'. The supply line 10 'passes through a longitudinal opening 26a' in the silicone rubber body 26 '. The compression of the bodies 20 'and 26' causes them to expand radially inwards and outwards and to effect a hermetic seal with the inner walls of the housing 2; the body 26 also effects such a hermetic seal with the supply line 10 '.

In the embodiment according to the Pig. 9 and 10, the plate 16 ', the silicone rubber body 20' and the support element 13 is introduced into the housing 2, which faces upward with the open end, in the lower end thereof, after which the Assembly of supply line 10 ', leg deformation member 24, silicone rubber body 26' and sealing disc 11 in the housing 2 is introduced. Then the supply line 10 'is pressurized with a predetermined downward pressure until the desired one Contact resistance between the Kontaktschenkein 10a and the housing walls is measured. Then the body becomes 20 ' partially compressed (cf. Pig. 9). Thereafter, the closure disk 11 resting on the housing shoulder 9 is in its position secured by the end portion 8a of the collar 8 is bent around the end of the closure disc. When the locking disc 11 is held against the shoulder 9, the forces acting on the composite body in the housing are such that they have a cause complete compression of the body 26 'and its expansion inwards and outwards, so that with the housing 2 and the Supply line 10 'creates a seal; the lead is through

909841/0644

2811950

Fixed friction in their position and maintains the desired contact resistance between the Kontaktschenkein 10a and the housing 2.

There can be certain areas of application of an environmental fuse that should normally be open, so that an electrical Control circuit is activated when the fuse is in an environment that is related to the tripping temperature the fuse is heated. In such a case, the fuse 1 ″ preferably has the structure according to FIGS. 11 and 12. A large one Number of parts of the fuse 1 ″, e.g. housing 2, supply lines 6 and 10, closure 11, epoxy body 14 and leg deformation member 24, are identical to the corresponding parts of the fuse according to FIG. 1 and are no longer explained.

The normally open fuse 1 ″ only requires a single coil spring 26 ″, which is positioned at the closed end of the housing. The coil spring 26 ″, which is partially compressed (see Fig. 10), is enclosed between the end wall 2b of the housing 2 and one end of a support element 13 'which is somewhat thicker than the support element 13 of the fuse 1. The support element 13' has a flat end face 13a ¹ which, when the support element 13 'is pushed against the contact legs 10a, spreads the contact legs 10a laterally outwardly in contact with the housing walls and presses them against them, so that a good low-resistance contact is formed therewith.

The contact legs 10a of the lead 10 are initially in the Cavity 24b of the leg deformation member 24 included. The support element 13 'acts against the flat surfaces of the spaced apart en projections 24d on one end of the member 24. The other end of the leg deformation member 24 acts against one end of the plate 16 ″ made of fusible material. The other end of the plate 16 ″ rests against the closure disk 11. if

9098A1 / 06U

the plate 16 "melts, the spring 26" presses the support element 13 'and the leg deformation member 24 to the left, so that the contact legs 10a from the cavity 24b move, come into contact with the flat end surface of the support element 13 'and are pressed into contact with the interior of the housing (see Fig. 12).

13-19 show an embodiment of a normally closed fuse IA, which with the fuse according to the Fig. 1-5 is essentially identical, but contains the helical spring according to FIGS. 6 and 7 and a lock 11 ', which replaces the closure 14 made of epoxy compound. This lock eliminates an assembly problem the fuse when using epoxy to close the housing and to set the set pressure on the supply line 10 occurs. The epoxy forming the closure is cured by placing the assembled fuse in an oven and heated to a desired temperature, which of course is below the target trigger temperature of the wafer lies. The curing of the epoxy takes a relatively long time (several hours) and it is therefore necessary to set the external force on the forked, the contact leg bearing Maintain supply line until curing is complete. Thus, the jigs and brackets for the Fuse to remain attached to this during curing. In the embodiment according to FIGS. 13-19, this becomes the contact legs applied set force automatically when anchoring a finished closure 11 'over the open Housing end made immutable; the finished closure does not require any curing for anchoring or fixing.

The closure 11 'consists of an elastically compressible insulating material, which is a highly heat-resistant synthetic resin (z. B. TORLON (Vz.) Grade 4203 from Amoco Chemicals Corporation). The closure 11 'acts against one at the junction between

$ 09841/0644

the thinner collar 8 and the thicker section of the cylinder wall 2a of the housing formed shoulder 9. The closure 11 'has an opening 11a ¹ through which the shaft 10b ^{1 of} a supply line 10' extends, which extends into the initially open end of the housing.

The closure II ¹ is divided over its entire length at lib 'and forms a gap ring body, the opening Ua' originally being larger than the diameter of the cylindrical shaft 10b 'of the supply line 10'. The split closure 11 'is pressed tightly around the lead 10' by the force of the end portion 8a of the collar 8 compressed around the closure. The outer end of the closure 11 'has an annular neck Hd' which forms an annular trough lld "with the shaft 10b 'of the supply line 10'. This trough lld" is filled with epoxy adhesive 14a to form a hermetic seal between the supply line 10 'and the closure 11'. An epoxy adhesive mass 14b is also over the circular connecting line applied between the upset end portion 8a of the collar 8 and the closure 11 '. An epoxy adhesive seam 14c is also applied to the opening at the junction of surfaces 11b '.

When assembling the fuse la before the contraction of the split closure 11 'around the lead 10' is the transition resistance between the contact legs 10a 'of the lead and the housing walls are set to a predetermined low setpoint value by gradually increasing the inwardly directed Pressure of the supply line against the support element 13 is increased until the target value is reached in the measurement of the contact resistance is. Then the split closure 11 'is pressed tightly against the supply line 10' by the collar 8 around the splash Hc ' of the closure is pressed before the set pressure is removed from the supply line. This setting will now explained in connection with FIGS. 16-18.

ÖÖ9841 / 06U

To assemble the various fuse elements in the housing 2, this is oriented so that its initially open end, which receives the closure 11 ', faces upwards and can accommodate the various parts, which are then successively in the lower housing part in the order in which they should be positioned in the housing, are introduced (see, Pig. 14). Then force application units, z. B. plungers 30 and 32, moved downwards to the upper ends of the supply line 10 'and the closure 11'. According to Pig, 17 the pressure stamp 32 is pressed downwards and brings the underside of the puddle lic ^{1 of} the closure 11 'into contact with the shoulder 9 of the housing wall at the inner end of the collar 8, which is undeformed, ie which protrudes straight up. This positioning of the closure 11 'presses the pedals 20 and 26 together. An ohmmeter 34 is electrically connected to corresponding points on the leads 6 and 10 '(e.g. at points which are each spaced approximately 12.7 mm from the free inner end portions of these leads). The plunger 30 is moved downward and presses the contact legs 10a ^f against the support element 13, so that the contact legs are spread outwards against the inner surface of the housing 2, with such a force that the desired contact resistance between the contact legs 10a ' and the walls of the case (which represents most of the resistance sensed by ohmmeter 34). When the ohmmeter detects the desired resistance, which gradually decreases with increasing downward force on the lead 10 ', the end portion 8a of the collar 8 is compressed or pressed ^{tightly around the surface 1 of the closure;} the closure initially formed a relatively large gap between the dashed lines 35 in Pig. 19. Then the closure is fixed in its position on the shoulder 9 and immovably attached to the shaft 10b 'of the supply line 10' (see. Pig. 18), where the desired force acting on the supply line is maintained after the plunger 30 of the lead 10 'is removed.

909841/0644

Then epoxy adhesive drops 14a, 14b and the seam 14c are placed on the space in the gap lib ^{1 of} the closure and on the joints between the closure ^11f and the housing 2 and the supply line ^10f (i.e. over the compressed section of the collar and on the adjacent supply line surface and in the trough lld ") to make the initially open housing end hermetically sealed. Of course, the epoxy is first applied in an uncured, soft state. Then it is cured by placing the finished fuse in an oven and heating it to a desired curing temperature The respective curing temperature depends on the temperature sensitivity of the fuse. Since curing takes at least a few hours, the exact time being a reverse puncture of the curing temperatures, the highest curing temperature that the plate 16 can safely withstand is selected '' consists of a highly heat-resistant synthetic resin, that can withstand the corresponding curing temperatures, ( ^{e.g. the curing temperature in a pail was 66 0} C, and the curing time of the epoxy adhesive was 1h) the fuse required, so that curing is greatly simplified.

With the normally closed fuse IB according to the Pig, 22-25 also results in an advantageous assembly and an adjustment method for the contact resistance according to the Process explained above, The fuse IB has a closure 11 "and a supply line 10", which is slightly different from the The closure 11 'and the supply line 10' differ. The closure 11 "is a plague body made of a rigid material, e.g. made of a suitable ceramic material, The closure 11" has a central opening 11a "which is permanently larger than the diameter of the shaft 10b" of the feed line 10 "passing through it is. Otherwise, the shape of the closure 11 ″ is corresponding

that of the shutter 11 ', the shutter 11 "has however no longitudinal division.

The inner or lower end of the shaft 10b "of the supply line 10" lies immediately after the lower section of the closure 11 ", which has an annular lip He" which acts against an axially outwardly facing shoulder 38 which is supported by a resiliently expanded portion of the shaft 10b "is formed. The annular lip He" presses against the resiliently expanded Section of the supply line for achieving the desired downward or inward pressure on the supply line 10 ″.

The assembly as well as the adjustment procedure for this embodiment are in the Pig. 23, 24 and 25 shown. Pig. 23 shows the initial assembly of the various elements of the fuse IB after they have been placed in the open end of the housing in the correct order. Pig. 24 shows the action of a plunger 32 on the upper end of the closure 11 ". After the plunger 32 has been moved downwards, it presses the pedals 20 and 26 together and the feed line with the contact legs downwards. The end position of the closure 11" is through the Determined point at which the contact resistance between the contact legs 10a "and the housing reaches a target value, which is recorded by the ohmmeter 34. To ensure uniformity of the triggering temperatures of identically designed fuses, the position of the shoulder 38 of the lead 10" is selected that the target contact resistance is reached before the surface of the closure reaches the housing shoulder 9. When the measurement by the ohmmeter indicates the target resistance, the originally straight end portion 8a of the collar 8 becomes tight around the surface of the closure pressed on. Epoxy adhesive drops 14a 'and 14b ¹ are introduced into the trough Hd "between the supply line 10" and the closure 11 "and between the section 8a of the collar 8 and the closure 11".

909841

The supply line 10 ″ can be mass-produced in a simple manner while maintaining close manufacturing tolerances (see Figs. 20 and 21). Individual supply lines are 10 " formed from a long cylindrical wire strand 40, the end portion of which in Pig. 20 can be seen. In this strand of wire relatively closely spaced pairs of axial slots 15 and 15 'are formed. The pairs of elongated holes 15 and 15 ' are so spaced that there is sufficient wire material between them to a lead 10 "with associated, outwardly inclined contact legs 10a " to shape. The end sections of these elongated holes are rounded, whereas their intermediate sections preferably have parallel sides to have. First, the end of the wire strand 40 is cut off so that the foremost elongated hole 15 is at the end of the wire strand opens along parallel slot sides. First, the legs 10a ″ forming the first elongated hole are bent outwards, see above that the contact legs 10a ″ are obtained (cf. Pig. 21). The wire is then cut through at a first point Pl, which forms the outer end of the severed lead element 10 ″, and at a second point P2, which is the outer end of the foremost elongated hole 15 of the next pair of elongated holes 15, 15 'opens, so that the next Supply line 10 "can be formed.

In the embodiment according to the Pig. 1-5 used supply line 10 can be produced with a similar process, wherein However, the wire strand has only one elongated hole 15 in each wire section to form a lead.

The invention makes a reliable and inexpensive one Fuse and a manufacturing method for it specified, the fuses being easily mass-produced and have essentially identical operating temperatures.

909841 / 06U

Claims (1)

Claims {1.! Thermal fuse, lfe is indicated by a housing (2) made of electrically conductive material; a first supply line (1O) in the housing (2), which passes through a housing opening, at which it is isolated relative to the housing (2), extends out of the housing (2) to the outside, with it on its inner end has deformable contact legs (1Oa) which are in low-resistance contact with the inner conductive surface of the housing (2) if they follow in a predetermined manner are spread out on the outside; a second outwardly exposed supply line (6) which is in permanent low-resistance connection with the housing (2); one between spaced-apart points in the housing (2) under spring pressure held composite body, consisting of tensioned springs (26, 20), a leg deformation member (24) for deformation the contact leg (10a) inwardly out of contact with the housing (2), a support element (13) for the contact legs (10a) for spreading the same against the housing (2) and forming a predetermined low-resistance contact therewith, and a melting body (16) which melts at a certain release temperature, so that the tensioned springs (26, 20) relax and either press the leg deformation member (24) or the support member (13) against the contact leg (10a). 2. Thermal fuse according to claim 1, characterized in that dai3 the contact legs (10a) are an integral part of the first Lead (10) are so that the interface between the contact schenkein (10a) and the housing (2) is the only separable contact interface between the supply lines (10, 6). 3. Thermal fuse according to claim 1 or 2, characterized in that that the housing (2) has a curved, electrically conductive inner surface having contacted by the contact legs (10a) is, and that the contact legs (10a) made of a relatively soft, There are highly conductive material that deforms when pressed against the housing (2) and over a larger Area forms contact with the housing (2), 4. Thermal fuse according to claim 1, characterized in that that the leg deformation member (24) is an insulating body with a cavity (24b), wherein the contact legs (10a), when deformed by the leg deformation member (24), fully retracted into the cavity (24b) so that the insulating body, the contact legs (10a) opposite the housing (2) completely isolated. 5. Thermal fuse according to one of the preceding claims, characterized in that that the melting body (16) made of a meltable granular material which is compressed in the closed end of the housing so that it expands and snugly against the free inner surfaces of the housing (2) is applied to the rapid absorption of external heat in the melting body (16). 6. thermal fuse,
marked by a housing (2) made of electrically conductive material; a first supply line (10) in the housing (2), which through a housing 909841 / nBU 291195Q se opening, at which it is isolated relative to the housing, extends out of the housing (2) to the outside, with it on its inside End laterally outwardly projecting, inwardly deformable contact legs (10a), which with the inner conductive Housing surface form a low-resistance contact; a second outwardly exposed lead (6) which is connected to the Housing is in permanent low-resistance connection; one between spaced-apart points in the housing (2) under spring pressure restrained composite body consisting of a first, fully compressed each (26), a leg deformation member (24), which is pressed by the first spring (26) to the contact legs (10a) and deforms them inwards, when the fully compressed spring (26) relaxes, a support element (13) for the contact legs (10a), on which these rest and are spread against the housing (2) to form a predetermined low-resistance contact with it, a second compressed spring (20) which keeps the first spring (26) fully compressed and any play receives within the composite body, and a melting body (16), which melts at a certain trigger temperature, where the support element (13) is fixed between the fully compressed and the second spring (26 or 20), that its position within the composite body is unchangeable as long as the fully compressed spring (26) in this State remains so that the contact resistance between the Kontaktschenkein (10a) and the housing (2) does not match the The degree of compression of the second spring (20) changes, and by the melting of the melting body (16) at the trigger temperature first the second spring (20) is relaxed and then the fully compressed spring (26) is relaxed, whereby the leg deformation member (24) is pressed against the contact legs (10a) and releases them from the housing (2). 1. Thermal fuse according to claim 6, characterized in that «0 * 041/06 * 4 that the contact legs (10a) are an integral part of the first Form feed line (10) so that the interface between the contact legs (10a) and the housing (2) is the only one separable contact surface between the supply lines (10, 6). 8. Thermal fuse according to claim 6, characterized in that that the solid body (16) made of fusible material from the completely compressed spring (26) and the leg deformation member (24) is spaced apart, and that the leg deformation member (24) directly adjacent to the contact legs (10a) is positioned so that the onset of relaxation of the fully compressed spring (26) is an immediate inward causes deformation of the contact legs (10a). 9. Thermal fuse according to claim 6, characterized in that that the housing (2) has a curved, conductive inner surface which can be contacted by the contact legs (10a), and that the contact legs (10a) made of a relatively soft, highly conductive Material that is deformable when pressed against the housing (2) and rests against it over a larger area. 10. Thermal fuse according to claim 8 or 9, characterized in that that the contact legs (10a) with the first supply line (10) are made in one piece so that they do not form a separable contact surface, the interface between the contact legs (10a) and the housing (2) is the only separable contact surface between the supply lines (10, 6). 11. Thermal fuse according to claim 6, characterized in that that the composite body comprises in the order given: 909941 / 06U the first, fully compressed spring (26; 26 '), which is directly between this and the contact legs (10a) positioned leg deformation member (24), the support element (13), the second spring (20) and the melting body (16; 16 ') 12. Thermal fuse according to claim 6, characterized in that the contact legs (10a) through openings in the leg deformation member (24) extend laterally outwards in contact with the housing (2). 13. Thermal fuse according to claim 11, characterized in that that the second spring (20) between the melting body (16 ') and the support element (13) is fixed. 14. Thermal fuse according to claim 13, characterized in that that the composite body has a first pressure distribution disk (18) between the second spring (20) and the melting body (16), and that the second spring is a helical spring (20). 15. Thermal fuse according to claim 14, characterized in that that one turn of the second spring (20) rests against the pressure distribution disk (18) on its circumference. 16. Thermal fuse according to claim 6, characterized in that the fully compressed spring (26 ') and the second spring (20') are solid bodies made of elastically compressible material which are spaced from one another on opposite sides of the contact legs (10a), the Springs (26 ¹ , 20 ') are expanded under compression and produce a hermetic seal with the housing walls. 609841 / 06U 17. Thermal fuse according to claim 16, characterized in that that the first supply line (10 ') is completely compressed Spring (26 ') penetrated, whereby the spring (26 ·) by the force the second spring (20 ') is expanded inwardly in hermetically sealed contact with the supply line. 18. Thermal fuse,
marked by a housing (2) made of electrically conductive material with conductive inner surfaces; a first lead (10 ') extending longitudinally into one end of the housing (2) at a point at which it is isolated relative to it, extends in the housing (2) in laterally outwardly extending, inwardly deformable contact legs (10a) ends, which form low-resistance contact with the curved conductive inner surfaces of the housing and with the first supply line (10 ·) are made in one piece so that they do not form a separable contact interface; a second supply line (6) which runs in the longitudinal direction into the other end of the housing and is thus in permanent low-resistance connection, the interface between the contact legs (10a) and the housing (2) being the only separable contact area between the supply lines (1O ¹ , 6 ) is; a longitudinally extending composite body which is fixed under spring pressure between the housing ends and comprises in the order given: a first, fully compressed spring (26 '), a leg deformation member (24) immediately between the first spring (26') and the contact legs (10a) is positioned, is pressed by the first spring (26) against the contact legs (10a) and this deforms inwards when the spring (26) relaxes, a support element (13) for the contact legs (10a), on the adjoining them 909841/0644 be spread against the housing (2) in order to produce a "certain low-resistance contact, a partially compressed spring (20 *)» which takes up play in the composite body, and a melting body (16 ') »which melts at a certain trigger temperature and im other end of the housing rests on its sides, so that it effectively absorbs the outside of the housing acting heat, the support element (13) between the fully and partially compressed spring (26 *, 20 ·) is determined so that its position in the Composite body is unchangeable as long as the fully compressed spring (26 ') remains in this state, so that the contact resistance between the contact legs (10a) and the housing does not change with the degree of compression of the partially compressed spring (20'), whereby the Melting of the melting body (16) at the trigger temperature first the partially compressed spring (20) relaxes, whereupon the fully compressed spring (26 ¹ ) presses the leg deformation member (24) against the contact legs (10a) and separates them from the housing (2). 19. A method for producing a thermal fuse, consisting of from a housing made of electrically conductive material with at least one initially open end for receiving the fuse elements during assembly of the fuse, a first exposed lead in the housing which is relative to the open housing part is isolated and has associated, laterally outwardly inclined contact legs, which are initially in electrical Contacting a conductive housing surface, a composite body in the housing comprising: a leg deformation member, which rests on one side of the contact legs and, if it is pressed against this with a certain force, compresses the contact legs and removes them from the conductive surface bends away, a support element on the other side of the contact leg, on which this inevitably becomes good electrical 909841/0644 " ⁸ " 29119SQ Contact with the conductive surface must spread, springs, and a fusible body made of a material that with a certain Release temperature melts and which keeps the springs in a tensioned state, so that when the melting body melts, the leg deformation member is released and compresses the contact legs out of contact with the conductive surface, and a closure which closes the initially open section of the housing in or on it so that it closes the springs keeps taut and the force of the contact legs against the Maintains support element, marked by Introducing the composite body and the first supply line with the associated contact legs into the housing; Applying an external force to the closure so that it rests against the composite body and the first lead and the contact legs are pressed against the support element, whereby the springs are tensioned and the contact legs against the support element are pressed in such a way that they are forced to spread on the housing; Setting the acting on the first supply line and the contact legs Force to such a value that the detected contact resistance between the housing and contact is not a gift has a predetermined low setpoint; and while maintaining the set the first feed line applying force permanent fixing of the closure on the initially open housing section, so that the springs applied load and the pressure of the contact legs against the conductive surface can be made invariable. 20. The method according to claim 19, characterized, that the closure is an elastically compressible body, which is first inserted into the open housing section, in which it loosely encloses the first supply line, after which by fixed 909841 / 06U -9- 291195Q place the closure tightly around the first supply line is pulled together before the external forces are released. 21. The method according to claim 19,
characterized, that the closure is a rigid body, that the first lead has an outwardly facing shoulder, and that the The first supply line acting force is exerted by an inner section of the closure acting against this shoulder will. 22. The method according to claim 20,
characterized, that the closure is anchored on the initially open housing section is by the housing walls are pressed tightly around an outer portion of the closure so that they pull it together around the first supply line, 23. The method according to claim 21,
characterized, that the closure is anchored on the initially open housing section by placing the housing around an outer section of the lock is pressed. 24. The method according to claim 19,
characterized, that the housing is cylindrical and the conductive surface is the inner surface of the housing is, 25. The method according to claim 19,
characterized, that the contact legs are an integral part of the supply line so that there is no contact interface between the two. Q09841 / 06U 2311950 26. The method according to any one of claims 19-25, characterized in that that the contact legs laterally outward into one of the open Housing section are inclined away leading direction that the support element on the outside of the contact legs and the leg deformation member are arranged on the inside of the contact legs, and that the contact legs of the external force must be pressed inwards before anchoring the clasp. 27. The method according to claim 20, 21, 22 or 23, characterized in that that after the anchoring of the closure to fix the load and the pressure acting on the springs, the contact loops against the conductive surface a plastic on the connecting lines between the closure, the housing and the first supply line is applied, and that after the release of the forces acting on the closure and the first supply line the fuse is brought into an environment, the temperature of which is increased to the hardening temperature of the plastic. 28. Thermal fuse,
characterized by a housing (2) made of electrically conductive material; a first supply line (10 ¹ ) in the housing (2) which runs out of the housing through a housing opening at which it is isolated relative to the housing, with inwardly deformable contact legs (10a) extending laterally outward at its inner end ¹ ) which form low-resistance contact with an inner conductive surface belonging to the housing (2); a second exposed supply line (6) which is in permanent low-resistance connection with the housing (2); a composite body of elements held in the housing under spring force between spaced apart locations, comprising: a tensioned spring (26), a leg deformation member (24) which is pressed by the spring (26) towards the contact legs (10a ») and deforms them inward when the spring (26) moves into the relaxed state, a support element ( 13) for the contact legs (10a ¹ ) »against which they are pressed so that they are spread out towards the housing (2) and thus establish a certain low-resistance contact, and a melting body (16) which melts at a certain trigger temperature, the spring (26) being relaxed by this melting and the leg deformation member (24 ^{) pressing against the contact legs (10a 1} ) so that they are bent away from the housing (2); and a closure (ll ¹ ) which is fixed in the housing opening and closes it tightly, the closure being an elastically compressed body into which the first supply line (10) runs and around which the boundary walls of the housing opening extend so that it is compressible around the first lead (10) and holds it in a position in which the contact legs (10a ¹ ) at the inner lead end are pressed against the support element (13). 29. thermal fuse,
marked by a housing (2) made of electrically conductive material; a first supply line (10 ") in the housing (2), which runs out of the housing (2) through a housing opening at which it is isolated relative to the housing, wherein it is inwardly deformable laterally outward at its inner end Has contact legs (10a ¹ ) which form low-resistance contact with an inner conductive surface of the housing; a second exposed lead (6) which is in permanent low-resistance connection with the housing (2); a composite body made of spring pressure between spaced-apart locations in the housing supported members comprising: a tensioned spring (26), a leg deformation member (24) supported by 109841/0644 the spring (26) is pressed against the contact leg (10a ') and it deforms inwards when the spring (26) relaxes, a support element (13) for the contact legs (10a '), against which these are printed so that they are spread open towards the housing (2) and with this a certain low resistance Form contact, and a melting body (16), which melts at a certain trigger temperature, whereby the Spring (26) moves into its relaxed state and the leg deformation member (24) against the contact leg (10a ') presses so that they are bent away from the housing (2); and a closure (H ") which is fixed in the housing opening and closes it tightly, the closure (H ") being a rigid body into which the first supply line (10") extends and around which the delimiting walls of the housing opening extend, the first supply line (10 ") being a outwardly facing shoulder (38) and the inner portion (He ") of the closure (H") presses against the shoulder (38) and the contact legs (10a ») at the inner end of the lead (10 ") presses against the support element (13). 30. Thermal fuse according to claim 28 or 29, characterized in that that adjacent surfaces of the closure (11 *; 11 ") and the Housing (2) and the first supply line (10 '; 10 ") are sealed with a sealing means (14a, 14b, 14c) so that the interior of the housing is hermetically sealed against the atmosphere. 31. Thermal fuse according to claim 29, characterized in that that the outwardly facing shoulder (38) by resilient projections are formed on the first supply line (10 "). 32. Thermal fuse according to claim 31, characterized in that that the supply line (10 ") has a shaft (1Ob") made of a resilient 90 ** 61/0644 29119SO ■ has flexible material with an elongated hole (15 ¹ ) penetrating it, which is widened so that the shaft (10Id ¹¹ ) is laterally inwardly curved and forms the outwardly pointing shoulder (38). 33 Thermal fuse according to Claim 28 or 29, characterized in that that the contact legs (10a; 10a ') form an integral part of the first supply line (10; 10 ^f ; 10 "), so that the interface between contact legs (10a; 10a ¹ ) and housing (2) is the only separable contact surface between the supply lines (10; 10 x; 10 "; 6). 34. Thermal fuse according to claim 1, 6, 18, 28 or 29, characterized marked, that the melting body (16) is a granular material which is compressed in the closed end of the housing that it is expands and lies tightly against the free inner surfaces of the housing, so that external heat can be quickly conducted into the melting body. 35. Thermal fuse according to claim 1, 28 or 29, characterized in that that the spring is a compressed hourglass-shaped coil spring (20A) with off-center intermediate turns (25, 27), so that the outer turns (21, 23) and the intermediate turns (25, 27) overlap and interlock to keep the length of the spring when compressed. 36. Thermal fuse according to claim 6 or 18, characterized in that that the second or the partially compressed spring is an hourglass-shaped helical spring (20A) with off-center intermediate turns (25, 27) is so that the outer turns (21, 23) and the intermediate turns (25, 27) in the compressed state overlap and interlock to keep the spring (20A) small. 37. thermal fuse,
marked by a housing (2) made of electrically conductive material; a first and a second supply line (10, 6) in the housing openings; movable contact legs (10a) in the housing (2), which with the one supply line (10) are connected and with a contact surface which is connected to the other supply line (6) form a low-resistance contact; a unit for separating the movable contact legs (10a), consisting of a composite body held under spring pressure between spaced apart locations in the housing, comprising: tensioned Springs (26, 20A) for applying the spring pressure, the tensioned springs having a compressed hourglass shape Have helical spring (20A) with eccentric intermediate turns (25, 27), so that the outer turns and the intermediate turns in the compressed state of the spring overlap and lie one inside the other to keep the length of the spring small; and a melting body (16) in the housing (2), which melts at a certain temperature and relaxes the spring (26) that the movable contact leg (10a) separates from the contact surface. 38. Thermal fuse according to claim 2, 7, 18, 28, 29 or characterized, that the contact legs (10a) and the first supply line (10) form a monolithic body formed from the same material. 39. Thermal fuse according to claim 1, 6 or 37, characterized in that that the fusible body (16) is a fusible granular material which is compressed in a housing end so that it is expands and lies tightly against the free inner surfaces of the housing, so that external heat quickly enters the compressed Melt body (16) is passed. 40. thermal fuse,
marked by a housing (2) made of electrically conductive material, which has a closed end from which a supply line (6) extends, and has an initially open opposite end; a melting body (16) made of granular material, which is in the closed Housing end is compressed so that it widens and rests tightly against the free inner surfaces of the housing (2), so that externally acting heat is quickly conducted into the melting body (16); an insulating closure (11; II ¹ ; 11 ") which closes the open end of the housing; a further supply line (10; 10 '; 10 ") leading through the insulating closure (11; 11»; 11 ") into the interior of the housing; and Current interruption elements (26, 24, 20) in the housing (2) which connect the end of the further supply line (10; 10 '; 10 ") to the housing walls electrically connect or interrupt the electrical connection when the melting body (16) melts.