EP2854149B1 - Temperature-dependent switch with a snap disc clasped at the edge - Google Patents

Description

The present invention relates to a temperature-dependent switch, which has a temperature-dependent switching mechanism and a housing receiving the switching mechanism, which comprises an upper part with a first outer terminal and a lower part with a second outer terminal, wherein on an inner side of the upper part in communication with the first outer terminal first contact surface and inside in the lower part provided with the second outer terminal second contact surface are provided, wherein the switching mechanism comprises a snap disc on which at least one outer contact region and at least one inner contact region are provided, wherein held on the inner contact portion a movable contact part is, which cooperates with the first contact surface, wherein the at least one outer contact region is mechanically and electrically permanently connected to the second contact surface, and wherein the snap disc, the movable contact part in Depends on the temperature of the rear derailleur from the first contact surface lifts.

Such a switch is from the DE 10 2011 119 637 A1 known.

The known switch has a pot-like lower part, which is closed by a lower part cross-top part. In the interior of the switch, a temperature-dependent switching mechanism is arranged, which carries a movable contact part, which cooperates with a stationary counter-contact, which is arranged on an inner side of the upper part and forms a first contact surface.

The derailleur comprises a spring snap-action disc, which carries the movable contact part and presses against the stationary counter contact. In this case, the spring snap disc is supported with its edge on the inner bottom of the lower part, which forms the second contact surface. In this position, the two contact surfaces are thus electrically conductively connected to one another via the movable contact part and the spring snap-action disc.

The external connections are made via the electrically conductive cover part, which is electrically conductively connected to the stationary mating contact, and the likewise electrically conductive lower part, on the inner bottom of which the spring snap-action disk is supported.

Above the spring snap-action disc, a bimetallic snap-action disc is arranged, which rests loosely in the rear derailleur in its low-temperature position. When the temperature of the bimetallic snap disk rises to a value above its response temperature, it presses with its center the movable contact part away from the stationary mating contact, for which it bears with its edge against an insulating film provided between the lower part and the upper part. The spring snap-action disc jumps from its one to its other stable geometric configuration.

While in the exemplary embodiment described so far, the snap-action disc is a spring snap-action disc against which a bimetal snap-action disc operates, it is in the case of the DE 10 2011 119 637 A1 known switch also provided to use only a bimetal snap-action disc, so that the current flows directly through the bimetallic snap disk, which also causes the contact pressure between the movable contact part and the stationary counter contact when the switch is closed.

The snap disc is at the out of the DE 10 2011 119 637 A1 Known switch, for example, a circular disc having an inner contact region on which the movable contact member is welded. In order to avoid internal tension in the snap disk, the inner contact area is separated by a semicircular gap of the snap disk, which extends over an angle of more than 180 °.

At a portion of the outer edge of the snap disc, a connecting web is formed, which serves together with the rest of the edge as a second contact area. This connecting bridge is used for better handling of the rear derailleur during its installation and when inserting into the lower part. The connecting bar then becomes surface welded to the inner bottom of the base to provide a permanent electrical and mechanical connection between the snap disc and the second contact surface inside in the lower part. The second contact region is thus permanently connected in the region of the connecting web and, in the region of the edge, with the switch closed, with the second contact surface.

This construction offers the advantage that the material and manufacturing costs for the known temperature-dependent switch are lower than other switches, because as a lower part no rotary member is required, and because can be dispensed with the silvering both the snap disc and the lower part.

Due to the permanent galvanic connection of the snap disc with the second contact surface is ensured in the known switch that the contact resistance between the snap disc and lower part is very low. This eliminates one possible source of error that can occur during the final continuity test of a fully assembled temperature-dependent switch. It is quite possible that due to manufacturing tolerances of the contact resistance between the lower part of the housing and the snap-action disc is so large that the finished temperature-dependent switch must be discarded as broke.

Normally, however, temperature-dependent switches of the type mentioned above are provided with snap discs, loose with their edge, so freely movable resting on the inner bottom of the base or an inner circumferential shoulder in the lower part, so that the entire edge forms the outer contact area. Such switches are for example from the DE 43 45 350 A1 known. When jumping from one to the other geometric configuration, the snap disc stretches until its edge is lifted from the bottom of the base or the peripheral edge.

Because the spring-snap disc is at the out of the DE 43 45 350 A1 well-known switch is supported on a circumferential shoulder, it can when snapping with its center through the shoulder and its resting on the shoulder edge "through" on the lower ground to move, so snap through the edge while at the same time mechanically extending radially outward, which allows snapping without overcoming external mechanical counter forces ,

These mechanical degrees of freedom when snapping between the two geometric configurations are desirable because they have a positive effect on the life of the derailleur and the long-term stability of the switching temperature.

Although from the DE 10 2011 119 637 A1 known switch brings many advantages in terms of cost and installation, it has certain disadvantages, as far as the life of the switching mechanism and the long-term stability of the switching temperature, because the snap disc on the connecting web at one point of its circumference mechanically fixed to the inner bottom of the base connected is. This design allows neither a radial stretching nor an unobstructed snapping through the center of the snap-action disc, which is consequently subjected to external mechanical forces when it is being folded over.

The known temperature-dependent switches are used to protect an electrical device from excessive temperature. For this purpose, the supply current for the device to be protected is passed through the temperature-dependent switch, wherein the switch is thermally coupled to the device to be protected. At a specified by the transition temperature of the bimetallic snap disc response temperature the respective switching mechanism then opens the circuit by the movable contact part is lifted from the stationary counter contact.

Thus, the switch does not close again after cooling the device, it is also known parallel to the temperature-dependent switching mechanism to provide a self-holding resistor, preferably a PTC resistor, which is electrically short-circuited at the closed temperature-dependent switching mechanism is. When the rear derailleur now opens, the self-holding resistor takes over a portion of the current flowing so far and heats up enough to generate enough heat to keep the bimetal snap-action disc at a temperature above the response temperature. This process is called latching, it prevents a temperature-dependent switch closes uncontrollably again when the device to be protected cools down again.

While self-heating of the snap-action disk by the flowing current is often undesirable in such temperature-dependent switches, switches are also known in which a series resistor is additionally provided, which heats up in a defined manner by the flowing current of the device to be protected. If the current flow is too high, this series resistance heats up to such an extent that the transition temperature of the bimetallic snap disk is reached. In addition to monitoring the temperature of the device to be protected, the flowing current can be monitored in this way, the switch then has a defined current dependence.

Such switches have proven sufficiently in everyday use. If the switches do not open at the zero crossing of an AC supply voltage or DC applied, arcs and sparks form during lifting of the movable contact part of the stationary counter contact and / or lifting the edge of the power snap disc of the second contact surface.

The arcs that form and sparks that result lead to contact erosion and, consequently, to a long-term change in the geometry of the buttons of the movable contact part and stationary counter contact, which over time also leads to an increase in the contact resistance.

In addition to the contact erosion on the stationary counter contact and the movable contact part, contact erosion also occurs at the edge of the snap disks, which carry the movable contact part and produce the electrical connection to the second contact surface with its edge as outer contact region. in the Over the course of the switching cycles, this leads to damage to the edge of the snap discs also increase the volume resistance.

These problems even increase with the number of switching cycles, so that the switching behavior of the known switches deteriorates over time. Against this background, the life, ie the number of permissible switching cycles of the known switches is limited, the lifetime also depends on the Abschaltleistung, ie the current of the switched currents.

The DE 977 187 A suggests, therefore, in a temperature-dependent switching mechanism, which has only a bimetallic snap disk to relieve them from the current flow, that the movable contact part is connected via a sun-wheeled metal spider to the housing of the switch. In this way, the current no longer flows only through the bimetallic snap disk but mainly through the metal spider.

A similar approach chooses the AT 256 225 A in which on the remote from the stationary mating contact surface of the bimetallic snap disk, a copper lead is provided, which connects the movable contact part with the housing.

The copper lead and the metal spider do not contribute to the mechanical function of the switch, on the contrary they must be moved by the bimetallic snap disk when opening and closing the switch, so they represent an additional mechanical load for them. This leads to fatigue and concomitantly not only to an undesirable shift in the switching temperature but also to a deteriorated opening and closing behavior, which greatly limits the life.

The DE 1 180 446 shows a comparable temperature-dependent switch with a bimetallic disc on which rests a slotted guide plate. This slotted Leitteller can with wheel-like S-spokes or according to a Leitspirale be equipped. The Leitteller serves only the power supply and is designed as a metal spider. The baffle does not have the characteristics of a snap-action disc, because it should not affect the mechanical properties of the bimetallic disc.

The EP 0 678 891 A1 shows a temperature-dependent switch with a bimetallic snap disk and a spring snap disc, which is equipped with four radial slots to increase the electrical resistance between the outer periphery of the disc and the inner edge region and thus the total resistance of the disc. Furthermore, the slots serve as ventilation openings. The spring snap-action disc is divided by the slots into four quadrants, which in themselves are rigid and non-compliant.

The WO 99/01879 A shows a bimetallic snap-action disc, which is soldered on a substrate via three legs extending outwards and downwards at about 45 ° away from the bimetallic disc. The legs must not be unstable, because they should provide the counterforce, so that the snap disc can buckle back and forth.

While these switches, the bimetallic snap disk must indeed provide the closing pressure of the rear derailleur, but this mechanical stress can be taken into account in certain types of switches.

Based on that suggests the DE 21 21 802 A to arrange parallel to the bimetallic snap disk a spring snap-action disc, which contributes to the mechanical function of the switch by making the closing pressure of the switching mechanism and supports both the opening and closing the Umschnappbewegung the bimetallic snap disk. In addition, it also carries the electrical power. In this way, the bimetallic snap disk is both mechanically and electrically relieved, so that their life is significantly extended.

There is this switch already at the beginning of which from the DE 43 45 350 A1 known switch described problem with the itself inevitably forming arcs and sparks, the more limiting the life of the known switches, the higher the switched current.

In the from the DE 10 2011 119 637 A1 Although known switch the contact erosion at the edge of the snap-action disc is reduced by the permanent electrical connection of the snap-action disc with the second contact surface, but still flows with the switch closed, so if the edge of the snap-action disc on the second contact surface, power not only via the connecting web but also over the edge of the snap disk in the second contact surface, so that the edge is damaged by contact erosion when opening the switch, which does not deteriorate the volume resistance but probably the mechanical switching behavior and thus the life.

Against this background, the present invention has the object to increase in a structurally simple way the life and / or the switching capacity of the known temperature-dependent switch.

According to the invention, this object is achieved in that the snap disk between the at least one or each outer contact region and the at least one or each inner contact region has at least one compensating section, which is formed yielding in the radial direction.

By "the or each permanently on the second contact surface resting outer contact area" is understood in the invention that all the areas of the snap-action disc, which are used for the electrical connection to the second contact surface, permanently rest on this, so for example by pressing , Gluing or welding are connected to it, and which do not stand out when opening the switch from the second contact surface.

For the out of the DE 10 2011 119 637 A1 Known switch would mean the implementation of the idea underlying the invention, for example, that the snap disk is equipped with a plurality of connecting webs along their Circumference arranged distributed and are each welded to the bottom of the base. The connecting webs, of which, for example, three are arranged offset by 120 °, then make the only electrical and mechanical connection between the snap disk and the second contact surface ago. The remaining edge of the snap-action disc is without mechanical and electrical contact.

This structurally simple measure solves the problem of contact erosion on the outer contact area because the or each outer contact area is completely and permanently connected to the second contact area. There are therefore no longer any portions of the outer contact area that can stand out on opening the switch from the second contact surface, which would lead to contact erosion.

At the same time, the snap disc is symmetrically fixed to the second contact surface, so that it mechanically shows a uniform switching behavior. However, the snap disc must overcome external forces when snapping.

It is of course possible that not every outer contact area is also welded, glued or clamped itself. It is only important that each outer contact area rests permanently on the second contact surface. This can be achieved, for example, if six circumferentially equally distributed connecting webs are provided, of which only every second one is connected to the second contact surface. The other connecting webs are thus permanently pressed firmly on the second contact surface, so remain connected to her even when the switch opens.

The life of the known switch is significantly extended in this way

The contact erosion at the edge of domes leads to knowledge of the inventors of the present application namely that the maximum switching capacity and the achievable switching cycle number are limited more than by the Contact erosion on the stationary mating contact and the movable contact part. Simply by improving the contact erosion at the edge of the current-carrying snap discs can thus be unexpectedly increase the life of a temperature-dependent switch.

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

Snap discs of the type used here are slightly curved discs with slightly raised towards the edge center. The domes are generally round, circular, oval or similarly rounded. Bimetal domes have a high temperature position in which they are convex in one view while appearing concave in the same view when in their low temperature position.

By contrast, spring snap disks have two mechanically stable geometric positions or configurations which, depending on the view, appear as convex or concave.

Snaps snap from their one configuration to the other by moving their center, as it were, through the edge, which tends to make a radial evasive movement. When the edge is firmly clamped, snapping over is done by internal deformation while overcoming internal forces. These internal deformations and the resulting internal forces lead to mechanical stress and aging of the snap discs, which limits the life of the switches equipped with it.

In order to avoid or at least greatly reduce the occurrence of the internal deformations and internal forces when the snap disc is at least partially mechanically fixed at its edge, compensating sections are now provided according to the invention inside the snap disk, which allow the mechanical deformation.

In the context of the present invention, a "compensating section" of the snap-action disc is thus understood to mean an area which is, so to speak, designed to be yielding or resilient in the radial direction. A compensating portion of the snap-action disc permits radial evasion or expansion movement within the snap-action disc, although the outer contact portion can not move or move radially outwardly relative to the second contact surface. This property of a compensation section results from its structure, ie its geometry and / or connection with the snap-action disk, the outer and / or the inner contact region. A compensation section can therefore also be referred to as an expansion structure.

The outer contact region may be formed, for example, as an outer ring, which is connected via a plurality of webs with the central region of the snap disk, which is followed radially inwardly by the inner contact region. The outer contact area is clamped onto the second contact surface. If the inner contact area of the snap-action disk, which carries the movable contact part, now snaps together with the middle area, then the webs deform temporarily by performing an evasive movement and / or being resiliently compressed. So they make a compensatory movement, which relieves the central area of the snap disc of the mechanical stress and thus slows down the aging processes.

A comparable compensation structure may alternatively or additionally also be provided between the inner contact region and the central region of the snap-action disc.

The structurally simple measure of the compensation sections ensures that the snap disk does not have to overcome any external forces when snapped over, because the snap disk makes a compensating movement in the radial direction between the outer contact area and the inner contact area, because the compensation section is designed to be resilient, for example. The snap-action disc can thus expand radially internally when the switch is opened and closed, without having to overcome external forces.

If the snap disc as the switch from the DE 10 2011 119 637 A1 welded to the second contact surface via a connecting web extending from the edge, this leads to mechanical problems without the contact erosion at the edge of the snap disk being completely eliminated.

Because only a single connecting web is provided, which is also firmly connected to the snap disk and welded flat on the second contact surface, it can not radial evasive movement allowed. The snap disc bends rather asymmetrically at its free from the connecting web peripheral portion upwards, which is geometrically problematic and permanently leads to heavy mechanical loads.

If the bimetallic snap disk as with the switches from the DE 21 21 802 A or the DE 43 45 350 A1 assigning a current-carrying spring-type liquor slice, which is not mechanically fixed at its edge, this leads to contact erosion at the edge of the snap-action disc, which is associated with the above-described problems.

If the bimetallic snap disk as with the switches from the DE 977 187 A or the AT 256 225 A Assigning a current-carrying connection, which connects the movable contact part with the second contact surface, the contact erosion is indeed reduced, but the bimetallic snap disk is mechanically overloaded because it must move the copper lead or metal spider with.

All these problems are solved by the new switch in a structurally simple way.

The advantage of the compensating sections results, in particular, in connection with snap-action disks which are mechanically fixed at their edge at least to the extent that they are symmetrically and permanently connected both mechanically and electrically to the second contact surface so that no contact erosion can take place at the edge.

While the snap-action disc itself may be the bimetallic snap-action disc, it is preferred if the snap-action disc is a spring-loaded snap-action disc associated with a bimetallic snap-action disc held on the movable contact member.

The advantage here is that the bimetallic snap disk neither has to exert the mechanical closing pressure nor conducts the operating current of the device to be protected.

It is preferred if the bimetallic snap disk is held captive with play on the contact part.

Because now spring snap-action disc, bimetallic snap disk and movable contact part form a unit, the rear derailleur can be mounted and stored as a separate Halbfertigteil, with a separate examination of the rear derailleur is possible because the bimetallic snap disk is held captive, but has corresponding lots so that it can deform unhindered between its low temperature position and high temperature position.

In this measure, it is also advantageous that the bimetallic snap disk can be easily mounted and fixed on the movable contact part without the bimetallic snap disk being exposed to mechanical stresses in its centric region.

Such mechanical stresses should be avoided as far as possible in many applications with bimetallic snap disks, because these mechanical stresses cause the switching behavior of the bimetallic snap disk can not be set reproducibly or shifts unpredictably.

The jumping of a bimetallic snap-action disc between its low-temperature position and its high-temperature position above the transition temperature, namely at first approaching the transition temperature, gradually, it is said that the bimetallic snap disk creeps.

If the bimetal snap-action disc is subjected to mechanical stress during this creeping operation, this can cause the bimetallic snap disc to age faster or to shift its transition temperature, which is often undesirable in use.

In general, it is preferred if the bimetallic snap disk is arranged between the spring snap disk and the first contact surface.

Here it is advantageous that the bimetallic disc is, so to speak, above the spring snap-action disc, so that there is space below the spring snap-action disc to connect the or each outer contact region to the second contact surface.

On the other hand, it is preferred if the bimetallic snap disk is arranged on the side facing away from the first contact surface side of the spring snap disk.

Here it is advantageous that the bimetallic disc is, so to speak, below the spring snap-action disc, so that the spring snap-action disc is above the bimetallic snap disk and shields them from flying sparks, when opening the switch between the stationary mating contact and the movable contact part can arise. According to the inventors, this protective function of the spring snap-action disc has a particularly good effect when the spring snap-action disc is permanently connected to the second contact surface at the outer contact region.

It is preferred if the or each outer contact region is permanently connected by clamping with the second contact surface, wherein preferably the movable contact part is clamped to the at least one inner contact region.

By clamping or clamping is provided for a good mechanical and electrical connection of the inner and outer contact area, so that there can not be any damage due to opening contact surfaces.

In general, it is preferred if the or each compensation section is resilient in the radial direction, preferably the or each outer and / or inner contact area is formed on a radially extending web, which is preferably connected exclusively via a compensation section with a central region of the snap disk.

The advantage here is that the compensatory movements when snapped through the structure can be predetermined in a structurally simple manner, for example, by the compensating section being formed as a high-arched section between the outer or inner contact region and the central region of the snap-action disc.

It is further preferred if at least three webs are provided, wherein preferably the outer and / or inner contact areas are connected to a ring.

Here it is advantageous that, although a large outer and / or inner contact area is provided so that the current flows evenly through the snap disk, but that over the webs structurally simple a resilient compensation movement can be adjusted.

Alternatively, it is preferred if the outer and / or inner contact region is formed as a self-contained ring, which is connected via a compensation portion with a central region of the snap-action disc, wherein the compensation portion at least one outer, circumferentially extending gap and at least one inner, in the circumferential direction extending gap, wherein the two gaps partially overlap in the circumferential direction, and preferably the two gaps are connected by an inwardly extending gap with each other, more preferably at least three outer and three inner column are provided.

In this way, a resilient structure is created in the snap disk, which allows the compensatory movements without strong material deformations, because an expansion in the column is possible.

It is preferable for the balancing portion at the outer contact portion when the inner gap extends over an angular range which is at most half the angular range over which the outer gap extends, and is preferable for the balancing portion at the inner contact portion when the inner gap extends over an angular range which is at most as large as the angular range over which the outer gap extends.

According to the inventors of the present application, this relation of the circumferential extent of the gap to one another gives on the one hand sufficient mechanical stability for the snap-action disc, but on the other hand permits the necessary compensatory movements without problems.

The new switch can be equipped with a parallel resistor for latching and / or with a series resistor for defined current dependence.

Further advantages will become apparent from the description and the accompanying drawings.

Fig. 1

eine schematische, geschnittene Seitenansicht eines temperaturabhängigen Schalters in geschlossenem Zustand;

Fig. 2

einen vergrößerten Ausschnitt des Schalters aus Fig. 1 im Bereich der Schulter, auf der der Rand der Feder-Schnappscheibe aufliegt, mit einem Ausführungsbeispiel für die Ausgleichsabschnitte;

Fig. 3

die Feder-Schnappscheibe aus Fig. 2 in einer schematischen Draufsicht;

Fig. 4

in einer Darstellung wie in Fig. 3 ein zweites Ausführungsbeispiel für die Feder-Schnappscheibe; und

Fig. 5

in einer Darstellung wie in Fig. 3 ein drittes Ausführungsbeispiel für die Feder-Schnappscheibe.

Embodiments of the invention are illustrated in the accompanying drawings and are explained in more detail in the following description. Show it:

Fig. 1

a schematic, sectional side view of a temperature-dependent switch in the closed state;

Fig. 2

an enlarged section of the switch Fig. 1 in the region of the shoulder, on which rests the edge of the spring snap-action disc, with an exemplary embodiment of the compensation sections;

Fig. 3

the spring snap-off Fig. 2 in a schematic plan view;

Fig. 4

in a representation like in Fig. 3 a second embodiment of the spring snap-action disc; and

Fig. 5

in a representation like in Fig. 3 a third embodiment of the spring snap-action disc.

In Fig. 1 is a schematic side view of a circular in plan view of temperature-dependent switch 10 is shown, which has a temperature-dependent switching mechanism 11 which is arranged in a housing 12.

The housing 12 comprises a pot-like lower part 14, which is closed by an upper part 15. In the lower part 14, a circumferential, stepped shoulder 16 is provided, on which a spacer ring 17 is arranged, on which the upper part 15 rests with intermediate storage of an insulating film 18.

By its inwardly bent, upstanding edge 19, the lower part 14 clamps the upper part 15 on the spacer ring 17 and this on circumferential shoulder 16th

Lower part 14 and upper part 15 are made in the embodiment shown from electrically conductive material, which is why the insulating film 18 is provided, the lower part 14 and top 15 electrically insulated from each other.

On an outer side 21 of the upper part 15, a further insulating cover 22 is provided, while on an inner side 23 of the upper part 15, a stationary counter-contact 24 is arranged.

With this stationary mating contact 24, a movable contact part 25, carried by the switching mechanism 11, works together.

The rear derailleur 11 comprises a spring snap-action disc 26, which is permanently clamped with its edge 27 between the spacer ring 17 and the shoulder 16, so that it produces a permanent electrically conductive connection there.

Below the spring snap-action disc 26, that is on its side facing away from the stationary counter-contact 24 side, a bimetal snap-action disc 28 is provided, which has two geometric temperature positions, the in Fig. 1 shown low-temperature position and a high-temperature position, not shown.

The bimetallic snap disk 28 lies with its edge 29 freely above a wedge-shaped, circumferential shoulder 31, which is formed on an inner bottom 32 of the lower part 14.

The lower part 14 also has an outer bottom 33, which together with the outer side 21 of the upper part 15 of the outer terminal of the switch 10 Fig. 1 serves.

The bimetallic snap disk 28 is supported on a peripheral shoulder 34 of the contact part 25 with its center 35.

The spring snap-action disc 26 is permanently connected to the inner contact region 36 in its center with the movable contact part 25, on which a pin 37, which projects through the two snap discs 26 and 28, a ring 37 is pressed on which also the shoulder 34th is trained.

The stationary mating contact 24 forms a first contact surface 38, which cooperates with the movable contact part 25 and via this with the inner contact region 36 of the spring snap-action disc 26 and is connected via the upper part 15 with the outer side 21, ie the first outer connection.

The shoulder 16 forms a second contact surface 39 for an outer contact region 41 on the edge 27 of the spring snap-action disc 26, which is mechanically and electrically permanently connected to the second contact surface 39, via the lower part 14 with its outer side 33, ie the second outer terminal connected is.

Radially inside the outer contact region 41, the spring snap-action disc 26 then has a compensation section 42, which connects the outer contact region 41 to a central region 43 of the spring snap-action disc 26, which is connected to the inner contact region 36 via a further compensation section 44.

In this way, inner and outer contact region 36 and 41 are firmly clamped by a respective clamping, so permanently connected mechanically and electrically, so that it can not come to the formation of sparks and / or arcs in these areas, so that contact erosion is avoided.

In order nevertheless to give the spring snap-action disc 26 the possibility of being able to expand mechanically at the time of snap-fitting, the radially resilient compensation sections 42 and 44 are provided, as will be discussed below.

In the in Fig. 1 shown, closed switching position of the switch 10, the movable contact member 25 is pressed by the spring snap-action disc 26 against the stationary counter-contact 24. Because the electrically conductive spring snap-action disc 26 is connected with its edge 27 in conjunction with the lower part 14, which serves as the second mating contact of the switching mechanism 11, an electrically conductive connection between the two outer terminals 21, 33 is thus produced.

If now the temperature inside the switch 10 increases beyond the response temperature of the bimetallic snap disk 28, then it works from the in Fig. 1 shown convex configuration in a concave configuration in which its edge 29 in Fig. 1 moved upwards so that it comes from below into contact with the edge 27 of the spring snap-action disc 26.

The bimetallic snap disk 28 presses with its center 35 on the shoulder 34 and thus lifts the movable contact part 25 from the stationary counter contact 24.

The spring snap-action disc 26 may be a bistable spring washer, which is geometrically stable even in the open position of the switch, so that the movable contact member 25 does not come back into contact with the stationary counter contact 24 even if the edge 29 of the bimetallic snap disk 28 no longer presses against the edge 27 of the spring snap-action disc 26.

If now the temperature inside the switch 10 is lowered again, then moves the edge 29 of the bimetallic snap disk 26 down and comes into abutment with the wedge-shaped shoulder 31. With its center 35, the bimetallic snap disk 26 then presses from below against the spring snap-action disc 26 and pushes them back into their other geometrically stable position, in accordance with Fig. 1 the movable contact member 25 presses against the stationary mating contact 24.

In the present embodiment, the rear derailleur 11 in addition to the bimetallic snap disk 28, the current-conducting spring snap disk 26, wherein in the switching mechanism 11, only the bimetallic snap disk 28 may be provided, which would then be clamped with its edge 29 under the rotating ring 17, and the contact portions 36 and 41 and the balancing sections 42 and 44 would have.

It is also possible to arrange the bimetal snap-action disc 28 above the spring snap-action disc 26.

In Fig. 2 is an enlarged section of the switch 10 off Fig. 1 shown in the shoulder 16. It can be seen that the spacer ring 17 presses the outer contact region 41 on the second contact surface 39, which is formed as a lowered step on the shoulder 16. Between the spacer ring 17 and shoulder 16, a gap 45 is exaggerated in size.

The equalizing portion 42 is formed between the middle portion 43 and the outer contact portion 41, which are approximately at the same height, as a high-arched portion. When snapping the spring snap disc 26, the central portion 43 moves along the arrow 46 down and the balancing portion 42 is temporarily compressed radially. The central region 43 may thus extend radially outward along the arrow 47 temporarily.

In this way, the central region 43 of the spring snap-action disc 26 experiences no mechanical load during snap-fitting, which is associated with the advantages discussed in detail at the outset.

So that the compensating portion 42 can perform these movements, it is formed on a web 53, as is also made Fig. 3 shows, which is a schematic plan view of a first embodiment of the spring snap-action disc 26 according to Fig. 2 shows.

The spring snap-action disc 26 has in the embodiment of Fig. 4 a total of three webs 53, the equally distributed at 120 ° to each other around the edge 27 are arranged distributed around. Each web 53 has, radially outward, the outer contact region 41, which extends radially outward beyond the edge 27.

The web is separated at its sides 54 and 55 by a gap or incision 56 and 57 of the spring snap-action disc 26 so that it is connected only to the central region 43 via the compensating portion 42.

The spring snap-action disc 26 is clamped only on the three outer contact areas 41 on the second contact surface 39.

When snapping the spring snap-action disc 26, the three compensating portions 42 perform a compensating movement, as determined by the Fig. 2 has been described, so that the central region 43 can expand radially.

In its center, the spring snap-action disc 26 has a center hole 58, through which the movable contact part 25 projects with its pin 30. Three webs 59 protrude radially inwardly into the center hole 58 and each have an inner contact region 36 radially inward.

Each web 59 is separated at its sides 61 and 62 by a gap or indentation 63 and 64, respectively, from the spring snap-action disc 26 so that it is connected to the central region 43 only via the compensating section 44.

Like the webs 53, the three webs 59 are equally distributed at 120 ° to each other, wherein each web 53 is radially opposite a web 59.

In this way, the center region 43 can also extend radially inwardly when the spring snap-action disc 26 snaps around, which also reduces the mechanical loads during snap-fitting.

The spring snap-action disc 26 may also be equipped only with the webs 53 or only with the webs 59, wherein more than three webs 53 and / or 59 may be provided.

The compensating sections 42 and 44 can each be designed in this case as it is in Fig. 2 is shown.

In Fig. 4 a further embodiment of the spring snap-action disc 26 'is shown, in which the inner webs 59 are formed as in Fig. 3 , The outer webs 53 are as in Fig. 3 educated.

In deviation from Fig. 3 the outer contact areas 41 are connected by three ring sections 65 circumferentially to a self-contained ring 66, which serves as an outer contact area 41 in total.

Likewise, the inner contact portions 36 are connected by three ring portions 67 to a self-contained ring 68, which serves as an inner contact region 36 in total

The ring 66 is connected only to the central region 43 of the spring snap-action disc 26 via the three webs 53 and their compensation sections 42. Accordingly, the ring 68 is connected only to the central region 43 of the spring snap-action disc 26 via the three webs 59 and their compensation sections 44.

Fig. 5 shows a spring snap-action disc 26 ", in which also a circumferential ring 66 is provided as an outer contact region 41, which is connected via three angled webs with the central region 43 of the spring snap-action disc 26". Each angled web extends with its first portion 69 radially inwardly of the ring 66 and subsequently with its longer portion 70 in the circumferential direction.

Between the ring 66 and the central region 43 are circumferentially provided three outwardly extending, circumferentially extending column 71 and three more inwardly, also extending in the circumferential direction column 72, wherein the gaps 71, 72 in the region of the longer portion 69 in Partially overlap circumferential direction and are connected by inwardly extending column 73 with each other.

A comparable structure is also found in the center of the spring snap-action disc 26, where the inner contact region 36 is formed as a ring 74 which is connected via three angled webs to the central region 43. The three webs each have a first portion 75 extending radially from the ring 74 to the outside and an adjoining portion 76 extending in the circumferential direction.

Between the ring 74 and the central region 43 are circumferentially provided three outer, circumferentially extending column 77 and further inwardly three also circumferentially extending column 78, wherein the gaps 77, 78 in the region of the portion 76 in the circumferential direction partially overlap and are connected by inwardly extending column 79 with each other.

The sections 69, 70 form with the columns 71, 72, 73 as well as the sections 75, 76 with the columns 77, 78, 79 a balancing section.

These constructions also allow the central region 43 to temporarily dodge radially outwards and inwards when the spring snap-action disc 26 snaps around.

The outer gaps 71 cover an angle range 81 of 110 °, while the inner gaps 72 cover an angle range 82 of 35 °, which is therefore less than half the angle range 81.

Finally, the outer gaps 77 cover an angle range 83 of 50 °, while the inner gaps 78 cover an angle range 84 of 40 °, which is thus at most as large as the angular range 83.

Claims (13)

1. Temperature-dependent switch, comprising a temperature-dependent switching mechanism (11) and a housing (12) accommodating the switching mechanism (11), which housing comprises an upper part (14) having a first external connection (21) and a lower part (15) having a second external connection (33), wherein a first contact surface (38) which is connected to the first external connection (21) is provided on an inner side (23) of the upper part (14), and a second contact surface (39) which is connected to the second external connection (33) is provided inside the lower part (15), wherein the switching mechanism (11) comprises a snap-action disc (26), on which at least one outer contact region (41) and at least one inner contact region (36) are provided, on which inner contact region a movable contact part (25) is held, which interacts with the first contact surface (38), wherein the at least one outer contact region (41) is mechanically and electrically permanently connected to the second contact surface (39), and wherein the snap-action disc (26) lifts off the movable contact part (25) from the first contact surface (38) depending on the temperature of the switching mechanism (11),
   characterized in that the snap-action disc (26) comprises at least one compensation section (42, 44) between the at least one or each outer contact region (41) and the at least one or each inner contact region (36), said compensation section being flexible in radial direction.
2. Switch according to Claim 1, characterized in that the or each outer contact region (41) is connected permanently to the second contact surface (39) by means of clamping.
3. Switch according to Claim 1 or 2, characterized in that the or each compensation section (42, 44) is resilient in the radial direction.
4. Switch according to anyone of Claims 1 to 3, characterized in that the or each contact region (36, 41) is formed on a radially extending web (59, 53), which is connected to a central region (43) of the snap-action disc (26) via a compensation section (44, 42).
5. Switch according to Claim 4, characterized in that the compensation section (44, 42) is embodied as an upwardly arched section provided between the contact region (36, 41) and the central region (43) of the snap-action disc (26).
6. Switch according to Claim 4 or 5, characterized in that the web (59, 53) is connected to the central region (43) of the snap-action disc (26) exclusively via the compensation section (44, 42).
7. Switch according to anyone of Claims 4 to 6, characterized in that at least three webs (59, 53) are provided, and that the contact regions (36, 41) of the webs (59, 53) are connected to one another to form a ring (68, 66).
8. Switch according to anyone of Claims 1 to 3, characterized in that the outer contact region (41) is in the form of a closed ring (66), which is connected to a central region (43) of the snap-action disc (26) via a compensation section, wherein the compensation section has at least one outer slit (71) extending in the circumferential direction and at least one inner slit (72) extending in the circumferential direction, wherein the two slits (71, 72) partially overlap one another in the circumferential direction.
9. Switch according to Claim 8, characterized in that the two slits (71, 72) are connected to one another by a slit (73) extending from the inside outwards.
10. Switch according to Claim 8 or 9, characterized in that the inner slit (72) extends over an angular range (82) which is at most half the size of the angular range (81) over which the outer slit (71) extends.
11. Switch according to anyone of Claims 1 to 3, characterized in that the inner contact region (36) is in the form of a closed ring (74), which is connected to a central region (43) of the snap-action disc (26) via a compensation section, wherein the compensation section has at least one outer slit (77) extending in the circumferential direction and at least one inner slit (78) extending in the circumferential direction, wherein the two slits (77, 78) partially overlap one another in the circumferential direction.
12. Switch according to Claim 11, characterized in that the two slits (77, 78) are connected to one another by a slit (79) extending from the inside outwards.
13. Switch according to Claim 11 or 12, characterized in that the inner slit (78) extends over an angular range (84) which is at most the same size as the angular range (83) over which the outer slit (77) extends.

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