EP2280457A2 - Electrical surge protection element - Google Patents

Abstract

The element has a housing, and an overvoltage limiting component i.e. varistor (3), arranged in the housing. Terminal lugs (4, 5) are connected to respective poles of the overvoltage limiting component in an electrically conductive manner. A connecting element (6) electrically connects the protection element to a current path or signal path. The terminal lugs are connected with one another as a single-piece, and a free end of the connecting element turned away from the limiting component is designed as a plug-in contact.

Description

The invention relates to an overvoltage protection element having a housing, with at least one arranged in the housing overvoltage limiting component, in particular a varistor, with two terminal lugs each electrically connected to one pole of the overvoltage limiting component, in particular soldered or welded and with two connection elements for electrical connection the overvoltage protection element to the current or signal path to be protected, wherein in the normal state of the overvoltage protection element, the connection elements are in each case in electrically conductive contact with a connection lug.

The known overvoltage protection elements are generally designed as a "protective plug", which together with a device lower part form an overvoltage protection device. To install such a surge protection device, which is intended to protect, for example, the phase-leading conductors L1, L2, L3 and the neutral conductor N and possibly also the earth conductor PE, corresponding terminals for the individual conductors are provided in the known surge protection devices on the device base. For simple mechanical and electrical contacting of the device base with the respective overvoltage protection element, the connection elements are designed as plug pins in the overvoltage protection element, which are arranged in the lower device part corresponding, connected to the terminals sockets, so that the overvoltage protection element can be easily plugged onto the device base. This makes it possible to simply replace a defective overvoltage protection element without having to disconnect the conductors connected to the connection terminals of the device lower part.

In such overvoltage protection devices, the installation and assembly by plugging the surge protection elements is very simple and time-saving feasible. In addition, such overvoltage protection devices partly still have a changeover contact as a signal transmitter for remote signaling of the state of at least one overvoltage protection element as well as an optical status indication in the individual overvoltage protection elements.

The status display indicates whether the overvoltage-limiting component arranged in the overvoltage protection element is still functional or not. In particular, varistors are used as overvoltage limiting component, although it is also possible to use gas-filled surge arresters, spark gaps or diodes depending on the intended use of the overvoltage protection element.

From the DE 42 41 311 C2 is an initially described overvoltage protection element known. In the case of the overvoltage protection element designed as a protective plug, the first connection element is connected directly to the first connection lug on the varistor via a first flexible copper strip, while the second connection element is connected via a second flexible copper strip to a rigid separation element whose end opposite the flexible copper strip is connected via a solder joint the second terminal lug of the varistor is connected. The separating element is acted upon by a spring system with a force which causes the separating element to be moved away linearly during the separation of the solder connection from the connecting plate, so that the varistor is electrically disconnected under thermal overloading. In the known overvoltage protection element, a thermal separation device is thus provided for monitoring the state of the varistor. A remote signaling contact is actuated via a spring system when disconnecting the solder connection, so that remote monitoring of the state of the overvoltage protection element is also possible.

Also from the DE 699 04 274 T2 For example, an overvoltage protection element with a thermal cutoff mechanism is known. In this overvoltage protection element, one end of a rigid spring-loaded slider in the normal state of the overvoltage protection element is soldered both to the first connection element and to a connection lug connected to the varistor. An inadmissible heating of the varistor leads here too to a heating of the solder joint, so that the slider is pulled due to the force acting on it a spring from the junction between the first connection element and the terminal lug, resulting in an electrical separation of the varistor.

The plug-in connection elements, which are formed by the plug sockets arranged in the device lower part and the plug pins formed on the overvoltage protection element, must be able to transmit relatively high pulse currents and short-circuit currents. In addition, the plug contacts, d. H. the plug pins and the sockets, mechanically loaded during insertion and removal of the overvoltage protection element, so that in the known overvoltage protection elements correspondingly stable connection elements are used, which are connected via soldered or welded connections with the terminal lugs.

The present invention has for its object to provide a surge protector described above, which can be made simpler and therefore more cost-effective. The overvoltage protection elements should have the same electrical and mechanical properties as the previous overvoltage protection elements.

This object is achieved in the above-described overvoltage protection element in that the first terminal lug and the first connection element are integrally connected to each other, wherein the overvoltage limiting component facing away, free end of the first connection element is designed as a plug contact. According to the invention, the first connection tab of the overvoltage limiting component is thus designed such that its free end itself serves as a connection element. Characterized in that the first terminal lug and the first connection element are integrally formed, eliminates the previously required in the prior art additional production step in which the terminal lug is connected to the connection element by soldering or welding. In addition to the simplification of the manufacturing process of the overvoltage protection element is also ensured in the inventive integral formation of terminal lug and connection element that the "contact resistance" between the terminal lug and the connection element is minimal.

In practice, the connecting straps of the overvoltage limiting component generally have a relatively small material thickness, so that the mechanical strength of the connecting element acting as a free end of the terminal strap may not be sufficient to the plugging and Pulling the overvoltage element acting forces permanently withstand, without causing damage to the connection element and thus to a deterioration of the pluggable electrical connection between the overvoltage protection element and a lower device part. According to a preferred embodiment of the invention, therefore, the first connection element is folded such that it has a plurality of layers in the contact region. The contact region designates that region of the connection element in which the connection element is contacted by the corresponding socket of the device base in the inserted state of the overvoltage protection element. The folding of the connection element preferably takes place transversely to the longitudinal direction of the connection element or the connection lug. Sufficient is usually a single or double fold, so that the connection element has two or three layers in the contact area.
According to a further advantageous embodiment of the invention, the mechanical strength of the folded connection element is increased by virtue of the fact that their individual layers are connected to one another in a force, form or material fit. In this case, the connection region is outside the contact region, so that the contact properties of the connection element do not change due to the realized connection of the individual layers.

In a particularly preferred embodiment of the overvoltage protection element according to the invention, a positive connection is formed between the first connection element or the first connection lug and the housing. During the plugging and pulling operation of the overvoltage protection element, a force acts on the overvoltage-limiting component arranged in the housing, which is proportional to the static friction that must be overcome in order to insert the plug-in contact element into the corresponding plug socket of the device lower part or to pull it out of the plug socket. Through the realization of a positive connection between the first connection element and the housing, the plugging and drawing forces are transmitted directly from the housing to the plug contact, or the forces acting on the plug contact forces are absorbed by the housing, so that the overvoltage limiting Component acting forces when plugging or pulling significantly reduced or even avoided altogether.

According to a first embodiment variant, the free end of the first connection element has a fold, which engages in a corresponding receptacle in the housing wall of the housing. As an alternative to a fold, one or two laterally projecting lugs can also be formed on the first connection element, which also dive into corresponding receptacles in the housing wall of the housing and are held therein. According to a further embodiment, at least one hole is formed in the first connection element, into which protrudes a corresponding projection which is arranged on the housing wall, through which the connection element projects out of the housing.

The frictional connection between the connecting elements of the overvoltage protection element designed as plug-in contact and the corresponding plug sockets of the device lower part is generally realized by the spring properties of the plug sockets. For this purpose, the sockets may be formed, for example tulip-shaped. According to an alternative embodiment, the non-positive connection between the connection elements and the sockets of the device base is characterized in that not the sockets but the connection elements are resilient. For this purpose, at least two layers of the connecting element can be bent relative to each other such that the connecting element is designed to be resilient perpendicular to its longitudinal extent. The connecting element can be designed to be approximately V-shaped.

As with the known overvoltage protection elements described above, the overvoltage protection element according to the invention preferably also has a thermal disconnection device for monitoring the state of the overvoltage limiting component. For this purpose, in the normal state of the overvoltage protection element, the second connection lug is connected to the second connection element via a solder joint, the solder connection between the second connection lug and the second connection element realized at the soldering point then separating when the temperature of the overvoltage-limiting component reaches a predetermined limit temperature exceeds. So that when reaching the limit temperature separates the solder joint, that is, the connecting tab facing the end of the connection element is moved away from the terminal lug, either the connection element itself may be formed resiliently or acted upon by the force of a separate spring.

The overvoltage protection element according to the invention is preferably designed as a "protective plug", so that it forms an overvoltage protection device together with a corresponding device lower part. In this case, a plurality of parallel-connected overvoltage limiting components, in particular a plurality of varistors connected in parallel, can be arranged in the housing of the overvoltage protection element. If the overvoltage protection element has a double varistor, then in particular the middle, internal terminal strip of the double varistor can be integrally connected to the first terminal element of the overvoltage protection element.

Fig. 1

eine perspektivische Darstellung eines Ausführungsbeispiels ei- nes Überspannungsschutzelements,

Fig. 2

eine vereinfachte Darstellung eines Varistors mit einer ersten Ausgestaltung einer Anschlusslasche, eingesteckt in eine Ste- ckerbuchse eines Geräteunterteils,

Fig. 3

eine vereinfachte Darstellung eines Varistors mit einer zweiten Ausgestaltung einer Anschlusslasche, eingesteckt in eine Ste- ckerbuchse,

Fig. 4

zwei separate Darstellungen der Anschlusslaschen gemäß Fig. 2 und Fig. 3, jeweils eingesteckt in eine Steckerbuchse,

Fig. 5

eine Variante einer Anschlusslasche gemäß Fig. 4, eingesteckt in eine Steckerbuchse,

Fig. 6

eine vereinfachte Darstellung eines Varistors mit einer An- schlusslasche, ähnlich der Darstellung gemäß Fig. 3,

Fig. 7

zwei Prinzipdarstellungen der Befestigung des ersten Anschluss- elements des Varistors im Gehäuse,

Fig. 8

eine vereinfachte Darstellung einer alternativen Kontaktierung von Anschlusselement und Steckeraufnahme eines Geräteunter- teils, und

Fig. 9

eine Darstellung einer Ausführungsform einer erfindungsgemä- ßen Anschlusslasche mit Anschlusselement.

In particular, there are a variety of ways to design and develop the overvoltage protection element according to the invention. Reference is made to both the claims subordinate to claim 1 and to the following description of preferred embodiments in conjunction with the drawings. In the drawing show

Fig. 1

3 is a perspective view of an embodiment of an overvoltage protection element,

Fig. 2

2 shows a simplified illustration of a varistor with a first embodiment of a connection tab, plugged into a plug socket of a device lower part,

Fig. 3

2 shows a simplified representation of a varistor with a second embodiment of a connection lug inserted into a plug socket,

Fig. 4

two separate representations of the connection tabs according to Fig. 2 and Fig. 3 , each plugged into a socket,

Fig. 5

a variant of a connection tab according to Fig. 4 , plugged into a socket,

Fig. 6

a simplified representation of a varistor with a connection tab, similar to the illustration according to Fig. 3 .

Fig. 7

two schematic representations of the attachment of the first connection element of the varistor in the housing,

Fig. 8

a simplified representation of an alternative contacting of connection element and connector receptacle of a device lower part, and

Fig. 9

a representation of an embodiment of a connecting tab according to the invention with connection element.

The Fig. 1 shows an overvoltage protection element 1 with a housing 2, wherein in the housing 2, a surge-limiting component is arranged. In the illustrated embodiments, the overvoltage limiting device is a varistor 3; Alternatively, the overvoltage limiting component can also be formed by a plurality of varistors connected in parallel, in particular a double varistor. Likewise, a gas-filled surge arrester can be used as overvoltage limiting component.

The two poles of the varistor 3 are each electrically connected to a connecting lug 4, 5, in particular soldered or welded. Trained as a protective plug protective element 1 also has two terminal elements formed as plug contacts 6, 7, which protrude on the underside of the overvoltage protection element 1 through corresponding openings of the housing 2. The plug-shaped connection elements 6, 7 can be plugged into corresponding sockets 8 of a device lower part, not shown here, wherein in the Fig. 2 to 8 only one socket 8 - is shown schematically.

In contrast to the known from the prior art overvoltage protection elements, in which the terminal lugs 4, 5 and the connection elements 6, 7 are formed as separate components, the first terminal lug 4 is integrally connected to the first connection element 6 in the inventive protective element 1, d , H. the end of the terminal lug 4 facing away from the varistor 3 is designed as a connection element 6.

While in the embodiment according to Fig. 2 the thickness of the connecting element 6 corresponds to the thickness of the connecting plate 4, is in the in Fig. 3 illustrated embodiment, the connecting element 6 folded such that it has two substantially mutually parallel layers 61, 62 in the contact region 9; the connecting element 6 is thus double-layered, so that the material thickness of the connecting element 6 in the contact region 9 also doubles. By such a folding of the connection element 6, its strength and stability can be increased in a simple manner, so that the connection element 6 - despite the relatively small material thickness of the connection plate 4 - is not damaged even with multiple plugging into the socket 8 of a device base. Instead of a simple, in Fig. 3 and Fig. 4a shown folding, the connecting element 6 according to Fig. 4b also be folded twice, so that the connection element 6 in the contact region 9 three layers 61, 62, 63 has.

How out Fig. 5 can be seen, the mechanical strength of the connection element 6 can be further increased by the fact that the individual layers 61, 62 are mechanically connected to each other, wherein the connection portion 10 outside - namely arranged above the contact region 9, so that the contact properties between the connection element. 6 and the socket 8 are not affected.

Initially, it has been stated that the varistor 3 is arranged within a housing 2, wherein openings are formed on the underside of the housing 2, through which the connection elements 6, 7 protrude out of the housing 2. Due to the frictional force between the connecting elements 6, 7 and the sockets 8 in the lower part of the device acts when plugging on the lower part of the device and when removing the overvoltage protection element 1 of the lower part of the device, a force on the connection tab 4 with the connection element In order to reduce this force acting on the varistor 3, a form-fitting connection is formed between the first connection element 6 and the housing 2. According to Fig. 6 In this case, the free end of the connecting element 6 has a fold 11 which engages in a housing 13 formed in the housing 12 of the housing 2, so that the fold 11 is held in the housing wall 12.

In the embodiment according to Fig. 7a are formed on the first connection element 6, two laterally projecting lugs 14 which are held in two corresponding receptacles 15 in the housing 12. At the in Fig. 7b illustrated embodiment, the positive connection between the first connection element 6 and the housing 2 is realized in that in the connection element 6, two holes 16 are formed and the housing 12 corresponding to the holes 16 has two projections 17 which engage in the holes 16. If the overvoltage protection element 1 is separated from the lower device part, for which a user touches the overvoltage protection element 1 on the housing 2 and subtracts it from the lower device part, then the pulling forces are transferred directly from the housing 2 to the connection element 6, so that no varistor 3 is arranged on the housing 2 - or only a significantly reduced - force acts.

In the in the Fig. 1 to 6 illustrated embodiments of the overvoltage protection element 1 according to the invention the necessary to ensure good electrical contact between the connection elements 6, 7 and the sockets 8 contact force is ensured by the spring characteristics of the sockets 8, ie the sockets 8 are resilient, while the connection elements 6, 7 substantially are rigid. In Fig. 8 an embodiment is shown in which, in contrast, the socket 8 is rigid and the connection element 6 is resilient, so that the contact force between the connection element 6 and the socket 8 is realized by the spring characteristics of the connection element 6. For this purpose, the two layers 61, 62 of the connecting element 6 are bent relative to each other such that the connecting element 6 is formed in an approximately V-shaped, whereby the connecting element 6 is designed to be resilient perpendicular to its longitudinal extent.

Fig. 9 shows a representation of a preferred embodiment of a terminal lug 4 with an integrally connected connection element 6, wherein the connecting element 6 according to Fig. 3 is folded such that it has mutually parallel layers 61, 62. As in the presentation according to Fig. 7a are two laterally projecting lugs 14 on the connection element 6, namely on the layer 62, formed, which serve to fix the connection element 6 in the housing. To increase the stability of the connecting element 6, the two layers 61, 62 are firmly connected to one another at both points 18 by riveting.

Out Fig. 1 it can be seen that in the top of the housing 2, a viewing window 19 is formed, through which an optical status display can be read. The optical status display is in this case connected to the second connection element 7 such that the status display changes its state when opening a solder connection realized between the second connection element 7 and the second connection lug 5. While in the normal state of the overvoltage protection element 1 or the varistor 3, for example, a green portion of the optical status display is visible through the viewing window 19, located in the fault of the overvoltage protection element 1, a red section of the status display below the viewing window.

Claims (8)

Overvoltage protection element with a housing (2), with at least one in the housing (2) arranged over voltage limiting component, in particular a varistor (3), with two terminal lugs (4, 5) each electrically connected to a pole of the overvoltage limiting component, in particular soldered or welded, are and with two connection elements (6, 7) for electrical connection of the overvoltage protection element (1) to be protected current or signal path, wherein in the normal state of the overvoltage protection element (1), the connection elements (6, 7) each with a terminal lug ( 4, 5) are in electrically conductive contact,
characterized,
is that the first connection tongue (4) and the first connecting element (6) are integrally connected to each other, said remote from the overvoltage-limiting component, free end of the first connecting element (6) designed as a plug contact. Overvoltage protection element according to claim 1, characterized in that the first connection element (6) is folded in such a way that it has a plurality of layers (61, 62, 63) in the contact region (9). Overvoltage protection element according to Claim 2, characterized in that the individual layers (61, 62, 63) of the first connection element (6) are connected to one another, wherein the connection region (10) lies outside the contact region (9). Overvoltage protection element according to one of claims 1 to 3, characterized in that between the first connection element (6) and the housing (2) is formed a positive connection. Overvoltage protection element according to claim 4, characterized in that on the first connection element (6) has a fold (11) or at least one laterally projecting nose (14) and in a housing wall (12) of the Housing (2) to a fold (11) and the nose (14) corresponding receptacle (13, 15) are formed. Overvoltage protection element according to claim 4 or 5, characterized in that in the first connection element (6) at least one hole (16) and in a housing wall (12) of the housing (2) at least one of the hole (16) corresponding projection (17) are formed. Overvoltage protection element according to one of claims 2 to 6, characterized in that at least two layers (61, 62, 63) of the first connection element (6) are bent towards each other such that the first connection element (6) is formed perpendicular to its longitudinal extent springs. Overvoltage protection element according to one of Claims 1 to 7, characterized in that, in the normal state of the overvoltage protection element (1), the second connection lug (5) of the overvoltage limiting component (3) is connected to the second connection element (7) via a solder joint, the soldering point being at the solder joint realized solder joint between the second terminal lug (5) and the second connection element (7) then disconnects when the temperature of the overvoltage limiting component (3) exceeds a predetermined limit temperature.

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