GB2541573A

GB2541573A - Thermal switching element and contact element

Info

Publication number: GB2541573A
Application number: GB1618643.9A
Authority: GB
Inventors: Wolf Roland
Original assignee: INTER CONTROL Hermann Koehler Electrik GmbH and Co KG
Current assignee: INTER CONTROL Hermann Koehler Electrik GmbH and Co KG
Priority date: 2014-04-15
Filing date: 2015-03-30
Publication date: 2017-02-22
Anticipated expiration: 2035-03-30
Also published as: WO2015158535A1; DE202014101769U1; WO2015158535A9; CN106233415A; DE112015001810B4; GB2541573B; CN106233415B; DE112015001810A5

Abstract

Thermal switching device, in particular temperature controller, temperature limiter, temperature monitor or thermal link, for connection to a heating device of an object of utility, wherein the thermal switching device is in thermal contact with the heating device, comprising a first and a second connection (5, 6), preferably a plug-type connection, for connecting the thermal switching device to an electrical circuit, a temperature-response functional element, preferably a bimetallic element or a fusible element, for ensuring a temperature-dependent switching function of the thermal switching device for interrupting the electrical circuit, wherein a resilient contact extension (8, 9) is provided at at least one connection (5, 6).

Description

Thermal switching device and contact element

The present invention relates to a thermal switching device according to the preamble of claim 1 and a contact element for use in a thermal switching device.

Technological background

Thermal switching devices of the type involved above are in particular temperature controllers, temperature limiters, temperature monitors or thermal links which are each in thermal contact with the heating device of a utensil and which independently carry out a switching operation when a predetermined temperature threshold is exceeded. Above all, such thermal switching devices are conventionally used in utensils, such as, for example, water boilers, instantaneous water heaters, coffee machines, washing machines, dishwashers, steam cookers, irons and the like.

With temperature controllers, a bimetal snap dome which in accordance with the temperature assumes two stable snap positions (bending) (bistable bimetal snap dome) is generally used as an active component in this instance and, depending on the respective bending thereof, an electrical circuit is opened or closed again. In a thermal link, a melting device, for example, a melting tablet, by means of which an electrical circuit can be interrupted when a temperature is exceeded is provided as an active component in place of the bimetal snap dome. A corresponding thermal switching device in the form of a thermal temperature controller and a thermal link can be seen, for example, in DE 197 06 316 C2.

So-called thick-film heaters are increasingly being used nowadays as heating devices. In this instance, heating lines are impressed on a substrate, for example, a substrate of metal or ceramic material. Such a thick-film heater may be used, for example, as a heating plate for a kitchen stirring device or the like. Thick-film heaters have above all the advantage of a small spatial requirement. As a result of their generally high heating speed, they require particularly powerfully thermally connected, fast-reacting control and safety components. A particularly good thermal connection of the active components of thermal switching devices of the above-mentioned type on such a thick-film heater is therefore a new challenge. Internal tests have shown that the production of a fixed connection of the contact of a thermal switching device with respect to a contact of the thick-film heater by means of soldering is problematic since, as a result of the mechanical stresses which are introduced during operation as a result of temperature fluctuations, the soldering locations may become loose and consequently an adequate temperature control or thermal link can no longer be produced.

Object of the present invention

An object of the present invention is to provide a novel thermal switching device of the type mentioned in the introduction and a contact element which is suitable for this purpose which, even in the event of temperature fluctuations which occur during operation, permanently ensure secure contact of the thermal switching device to the thick-film heater.

Solution to the problem

The above object is achieved with the generic thermal switching device in that at least at one connection, preferably at both connections, a resilient contact extension is additionally provided. The resilient contact extension enables the respective connection of the thermal switching device, which is generally a planar contact which is positioned laterally on the thermal switching device and which protrudes outwards and which comprises a metal contact material without resilient action, to be contacted by means of pressing with the open contacts of a thick-film heater. It is thereby possible to connect the thermal switching device to the thick-film heater in a permanently reliable manner even in the event of considerable temperature-related stresses. At the same time, the invention also enables conventional thermal switching devices to be provided in a simple manner with the resilient contact extension.

The contact extension is preferably orientated from the electrical connection of the thermal switching device downwards in the direction of the abutment face of the housing of the thermal switching device and in this manner bridges the spacing between two contact connections of the thick-film heater which is located at the lower side of the thermal switching device. It is thereby possible to use conventional thermal switching devices in a simple manner for use in connection with a thick-film heater.

As a result of the fact that the contact extension protrudes beyond the lower side of the thermal switching device or the abutment face thereof, when the thermal switching device is assembled on the thick-film heater, a pressing pressure of the contact extension can be produced on the upper-side, open contacts of the thick-film heater. As a result of this pressing pressure, even in the event of temperature-related stress, an effective contacting is permanently achieved.

According to an advantageous embodiment of the present invention, the contact extension is secured in a non-releasable manner to the lower side of the connection, for example, by means of a laser weld connection, electro-welding connection, solder connection.

Alternatively, the contact extension may also be connected to the free end of the connection in a releasable manner, in particular in an insertable manner.

For example, there may be provided for this purpose an insertion shoe which is fitted to the contact extension in the manner of a cable lug so that corresponding contact extensions can also subsequently be fitted to completed components .

The insertion shoe may be connected to the cable extension by means of a weld connection, for example, by means of laser spot welds.

Advantageously, the contact extension is constructed as a leaf spring. As a result of the flat upper region thereof, which is preferably positioned at the lower side of the connection, the overall thickness of the connection is increased only insignificantly which affords the advantage that a conventional insertion shoe can still be fitted for electrical contacting. Furthermore, a leaf spring has the advantage that the contact extension can be produced in a simple manner by flat material being folded in the desired manner .

With a leaf spring, it is additionally possible to produce a plug type connection in the form of a cable lug in a particularly simple manner by means of receiving channels which are laterally bent open in the upper region.

According to an alternative embodiment, a resilient contact pin may be used as a contact extension.

According to another alternative embodiment, the contact extension may be fixed in its position in that the extension is placed in a housing or housing portion which engages over the connection. It is thereby possible to use as a contact extension even a loose contact element which is placed in position on the thick-film heater at the same time only as a result of the assembly of the thermal switching device or the housing portion thereof.

The protuberance at the end region of the contact extension at locations where the contact extension moves into electrical contact with the open contact of the thick film heater ensures the advantage that, even in the event of temperature-related stresses, the contact can carry out a rolling movement over the contour of the protuberance.

Advantageously, the protuberance is produced by means of embossing. Thereby, for example, a protuberance in the form of a spherical portion to be produced.

The invention mentioned in the introduction is achieved with the contact element according to the preamble of claim 14 in that the contact element is constructed as a resilient contact extension for the connection of the thermal switching device .

Preferably, the resilient contact extension is constructed as a leaf spring.

According to an advantageous embodiment of the contact element according to the invention, the resilient contact extension has a first angled contact region which is provided to be connected to the open contact at the thick-film heater.

Advantageously, the resilient contact extension may preferably have in the first angled contact region a protuberance which enables a rolling behaviour of the contact in the event of temperature-related stresses.

In order to simplify a fixing of the contact element to the connection of the thermal switching device, there is provided a second angled region which is preferably constructed in a planar manner. This enables a non-releasable connection, for example, welding by means of laser welding or electro-welding or the like. The contact element then has an open C-like shape .

Alternatively, the contact element may also have a closed shape, that is to say, when the upper-side connection region is formed by both free ends of the contact element. The contact element then has an Ω-like shape which is closed in the bridging region.

The upper-side connection region is preferably sized in such a manner that it does not protrude laterally and/or at the free end thereof beyond the connection of the thermal switching device or terminates at least substantially flush with the connection. It is thereby possible to use conventional connectors without adaptation being required.

It is also possible at a second angled end region of the contact extension for the contact element to be provided with the plug type receiving member or an insertion shoe which enables a plug type connection of the contact extension with the connection of the thermal switching device.

If the resilient contact extension is placed only in the housing and a contact is ensured at both end regions of the contact extension as a result of the pressing pressure of the resilient contact extension, it is advantageous for the second angled region to also have a protuberance.

As a result of the fact that the contact extension has at least one, preferably a plurality of retention projections, the extension can be securely positioned, above all when the contact extension is placed loosely in a housing portion and the contacting is carried out exclusively by means of a pressing pressure both on one and also on the other end of the contact extension.

Advantageously, the retention projections are retention wings which can be formed from the leaf spring by means of a simple punching operation and can be readily bent.

Description of the invention with reference to embodiments

Advantageous configurations of the present invention are explained in greater detail below with reference to embodiments. In the drawings:

Figure 1 is a simplified perspective illustration of a first embodiment of a thermal switching device according to the present invention in the form of a thermal link, when viewed obliquely from above;

Figure 2 is a simplified perspective illustration of the thermal switching device according to Figure 1, when viewed obliquely from below;

Figure 3 is a simplified side view of another embodiment of a thermal switching device according to the present invention in the form of a temperature controller;

Figure 4A is a highly simplified perspective illustration of a thermal switching device according to the invention in a state installed with a thick-film heater with two resilient connections;

Figure 4B is a highly simplified perspective illustration of a thermal switching device according to the invention in a state installed with a thick-film heater, each with a single resilient connection;

Figure 5A is a simplified perspective illustration of an advantageous embodiment of a contact element according to the present invention;

Figure 5B is a simplified perspective illustration of another advantageous embodiment of a contact element according to the present invention;

Figure 6 is a simplified perspective illustration of another advantageous embodiment of a contact element according to the present invention for retrofitting conventional thermal switching devices;

Figure 7 is another embodiment of a contact element for retrofitting conventional thermal switching devices;

Figure 8 is another embodiment of a contact element for retrofitting conventional thermal switching devices;

Figure 9 is an exemplary embodiment of a thermal switching device having a retention clamp and a common additional housing member, and

Figure 10 is another exemplary embodiment of a thermal switching device having a contact element with a closed shape.

Figure 1 shows a thermal switching device according to the present invention in the form of a thermal link 1. The thermal link 1 comprises a housing 1, preferably a ceramic housing, and a plate-like carrier 7 which carries the housing 3. Inside the housing 3 is a melting tablet 4 which, when a specific predetermined temperature is exceeded, ensures an interruption of the electrical connection.

At the upper side of the housing 3 there are, for example, two electrical connections 5, 6 which serve to incorporate the thermal switching device into an electrical circuit. Depending on whether the fuse has switched, the electrical circuit is either closed or open. The thermal link 1, which is generally located in the region of a heater or a medium which is intended to be heated, has for safety a specific switching characteristic.

According to the invention, the thermal link 1 has at least in the region of one connection, preferably in the region of both connections 5, 6, a resilient contact extension 8, 9.

The contact extension 8, 9 is in the illustration shown in

Figure 1 orientated downwards in the direction towards the abutment face A of the thermal link 1 and consequently bridges the spacing between the respective contact connection 5 or 6 and the upper side of the abutment face A of the thermal link 1.

In the embodiment illustrated in Figure 1, the resilient contact extension 8, 9 is constructed as a double-angled leaf spring. It has as a connection region an upper end region 19, 20 which is orientated parallel with the respective connection 5, 6. The lower-side end region opposite the upper-side end region 19, 20 is as a contact region also constructed in an angled manner and serves to contact with an open contact of a thick-film heater (cf., for example, Figure 4A or 4B). The lower end region may be bent with respect to the central region at an angle greater than 90° in order to ensure a resiliently induced pressing pressure.

In the lower region of the contact extension 8, 9 there may advantageously be provided a protuberance 13, 14 which serves to enable an easier rolling movement of the contact with respect to the opposing contact face of the thick-film heater in the event of temperature-related stresses. The protuberance 13, 14 is preferably in the form of a spherical portion. In the case of a contact extension 8, 9 which comprises a leaf spring, it can be embossed in a simple manner. Between the lower region of the contact extension 8, 9 and the perpendicularly extending central portion thereof, there is determined a radius of curvature which is greater than the radius of curvature between the upper-side end region 19 and 20 and the vertical region of the contact extension 8, 9.

Advantageously, the contact extension is sized in the connection region, that is to say, in the upper end region 19, 20, in such a manner that the extension does not protrude outwards and/or forwards over the outer edge region of the connection 5, 6. It is thereby readily possible in the embodiment of the thermal switching device illustrated in Figure 1 for a conventional electrical plug type element to be fitted to the respective connection 5, 6. It is consequently possible to use conventional connectors without an adaptation being required.

As can be seen in Figure 2, the respective contact extension 8, 9 is sized in such a manner that the contact region, that is to say, the lower region thereof, protrudes slightly beyond the abutment face A of the thermal switching device 1, whereby an advantageous pressing characteristic is provided as soon as the thermal switching device is positioned mounted so as to be secured in terms of movement on the surface of a thick-film heater. As can also be seen in Figure 2, the respective contact extension 8, 9 may be connected to the respective connection 5, 6 of the thermal switching device in a non-releasable manner. This may, for example, be carried out by means of laser spot welding, for example, in the form of one or more spot welds. A securing location of the laser spot welding is schematically designated 15 or 16 in Figure 2 by way of example.

Figure 3 shows a thermal switching device in accordance with the type according to the invention, wherein, in place of a thermal link 1, a temperature controller 2 is provided with a corresponding contact extension 8, 9, respectively. The temperature controller 2 also comprises, in a similar manner to the thermal link 1, for example, two connections 5, 6 to the lower side of which the respective contact extension 8 and 9 is secured in the manner described. With regard to the configuration and sizing of the contact extension 8 and 9, reference may be made to the above explanations. The temperature controller 2 has, in place of the melting tablet 4 of the thermal link 1 of Figure 1 or 2, a bimetal functional component 18, for example, in the form of a bimetal disc which, dependent on the ambient temperature, has two stable snap locations. Since with the temperature controller 2 direct switching is intended to occur when the fixedly predetermined temperature is reached, there is provided on the lower side of the controller 2 only one carrier 7 in the form of a very thin plate. A bimetal disc is located in a recess of this plate. The bimetal disc is consequently in direct contact with the thick-film heater, which brings about particularly rapid thermal switching behaviour .

Figure 4A is a highly simplified schematic illustration of a temperature controller 2 on a thick-film heater 10 which has a plate-like substrate, for example, of metal (provided with an electrically insulating intermediate layer, for example, enamel or silk-screen printed glass ceramic material) or ceramic material or the like, to which there are applied, preferably impressed, individual heat conducting tracks 11. The heat conducting tracks 11 are contacted by means of a connection wire 12 in each case with an electrical energy supply (not illustrated). At the location provided for the controller 1 or the fuse 2, in this embodiment of the thick-film heater, the heat conducting tracks 11 are interrupted in order to be able to switch in a controller 1 or a fuse 2 in the conductor path circuit. To this end, the temperature controller 1 or the thermal link 2 is positioned on the thick-film heater 10, for example, by means of a retention device (not illustrated) and the two connections 5, 6 are connected by means of the contact extensions 8, 9 to the open contact locations of the heat conducting track 11. In this instance, the lower-side end regions of the contact extensions 8, 9 are positioned loosely on the open contacts of the heat conducting track and ensure bridging of the otherwise open electrical current path. The embodiment has the advantage that, when temperature-related oscillations occur, a lasting effective contacting and consequently reliable operation can nonetheless be ensured.

The securing of the thermal switching device on the thick-film heater 10 may be carried out, for example, by means of a retention member which is not illustrated in Figure 4A and by means of which the thermal switching device is pressed onto the abutment face at the upper side of the thick-film heater 20 and is retained in a position secured in terms of movement.

In the thick-film heater 10 according to Figure 4B, the respective end of the heat conducting track 11 is connected to a thermal switching element, for example, in the form of a temperature controller 2. Consequently, a connection 5 of the relevant temperature controller 2 is in contact by means of a contact extension 8 with the end of the heat conducting track 11, whereas the additional connection 6 of the temperature controller 2 ensures an electrical contact with the respective connection wire 12. Consequently, with this arrangement, an additional contact connection to the power connection can be dispensed with. It is thereby in turn possible to reduce the susceptibility of the electrical contact connection to failure.

As an alternative to the illustrations in Figures 4A and 4B, the heat conducting tracks may also extend below the thermally sensitive components of the respective thermal switching device. The response times or actuation times can thereby be greatly decreased.

The illustration according to Figure 5A shows the contact extension 8 in the state prior to assembly on the connection 5 of the thermal switching device 1 or 2 of the embodiments according to Figures 1 to 3. The contact element is produced from a leaf spring which comprises metal (spring steel), bent at two positions and preferably provided by means of an embossing operation with a protuberance 13 in the lower end portion of the contact extension 8 forming the contact region. The upper end region 19, 20 is constructed in a flat manner so that it can be placed in a planar manner at the lower side of the respective connection 5, 6 and can be connected thereto at that location.

The variant of a resilient contact extension illustrated in Figure 5B is a contact element variant which is also produced from a leaf spring material and which is closed in the lower-side region and which has at the upper side two connection regions which are orientated towards each other for securing to the respective connection 5 or 6 of the thermal switching device 1 or 2. In the lower-side region, a protuberance 13 can also be provided. This variant of the contact element ensures as a result of its shape which is closed in the assembly state an increased resilient action. This contact spring also preferably protrudes downwards in the state fitted to the thermal switching element by means of notional extension of the horizontal abutment face A (cf., for example, Figure 1). This embodiment of the contact element has a closed shape in which the two open end regions of the contact extension, with a butt joint 28 being formed, form the upper-side contact region with the connection 5 or 6.

In the embodiment according to Figure 6, the upper end region 19 of the contact element is preferably integrally provided at both sides with receiving channels 21. The upper end region 19 consequently forms a type of insertion shoe. The receiving channels 21 may be introduced in a particularly simple manner in a leaf spring material by means of a type of flanging.

In the embodiment according to Figure 7, a resilient contact pin 25 is alternatively used as a contact extension. This may be connected to a corresponding upper portion as in Figure 6.

Figure 8C shows another embodiment of a resilient contact extension 9 in the form of a contact element according to the present invention. The contact element is constructed from a leaf spring and comprise both at the upper side and at the lower side a contact region having a protuberance 13. Both contact regions contact only by means of pressing pressure, one contact region contacts the connection of the thermal switching element, the other contact region contacts the open contact of the heating conductor track of the thick-film heater (see, for example, Figures 4a and 4b). The retention of the contact element is ensured by the housing 3 or an additional housing member 25 which at least partially surrounds the contact element, cf. bottom view with contact element according to Figure 8B, and thereby fixes it in position. The contact element is placed prior to assembly, cf. bottom view without any contact element, Figure 8A from below, into a pocket 26 which is formed by the housing 3 or the housing portion 25 and the connection 6 and subsequently fixed in position by means of securing the thermal switching device to the abutment face thereof. In order to fix the contact element, it may have two laterally arranged retention wings 23, 24 which engage, for example, on housing webs 17 of the housing or housing portion 25.

Figures 9A and 9B show a possibility for securing a thermal switching element according to the present invention to a thick-film heater which is not illustrated in Figure 9A or 9B. In the embodiment, for example, two temperature controllers 2 are accommodated in a common additional housing 25 which is secured, for example, by means of a curved member 27 to the upper side of the thick-film heater. To this end, the curved member 27 is, for example, welded at both ends thereof to the upper side of the thick-film heater. The two temperature controllers are connected at the connections 6 thereof to a connection wire which is not illustrated in Figure 9A or 9B in accordance with the embodiment of Figure 4B. In the two pockets 26 which are located in the region of the opposing connections 5, resilient contact extensions (not illustrated in Figure 9A or 9B) of the type shown in Figure 8C are placed and fixed in position by means of the assembled additional housing 25.

Figures 10A and 10B show the use of a contact element with a closed shape, as illustrated in Figure 5B. As in the embodiment of Figures 9A and 9B, this also involves, for example, two temperature controllers 2 which are accommodated in a common additional housing 25 which is secured by means of a curved member 27 to the upper side of a thick-film heater which is not illustrated. In this embodiment of the common additional housing 25, it covers only the upper-side region of the two temperature controllers 2. The curved member 27 is in this instance constructed as a peripheral frame. The resilient contact elements 8 are secured with the two open ends thereof in the connection region to the connection 5 with a butt joint 28 being formed. The respective contact element thereby has a closed Ω-like shape. Also in this instance, protuberances 13 for improving the rolling operation may be provided in the contact region in the thick-film heater.

LIST OF REFERENCE NUMERALS 1 Thermal link 2 Temperature controller 3 Housing 4 Melting tablet 5 Connection 6 Connection 7 Carrier 8 Contact spring 9 Contact spring 10 Thick-film heater 11 Conducting track 12 Connection wire 13 Protuberance 14 Protuberance 15 Securing location 16 Securing location 17 Housing web 18 Bimetal functional component 19 End region top 20 End region top 21 Receiving channel 22 Housing portion 23 Retention wing 24 Retention wing 25 Additional housing member 26 Pocket 27 Curved member 28 Butt joint

Claims

PATENT CLAIMS

1. Thermal switching device, in particular temperature controller, temperature limiter, temperature monitor or thermal link, for connecting to a heating device (14) of a utensil, wherein the thermal switching device is in thermal contact with the heating device (14), having a first and second connection (5, 6), preferably plug type connection, for connecting the thermal switching device to an electrical circuit, a functional element which reacts to temperature, preferably a bimetal element or a melting element, for ensuring a temperature-dependent switching function of the thermal switching device in order to interrupt the electrical circuit, characterised in that a resilient contact extension (8, 9) is provided at least at one connection (5, 6).

2. Thermal switching device according to claim 1, characterised in that the contact extension (8, 9) is orientated downwards in the direction of the abutment face (A) of the housing (3) and bridges the spacing between the connection (5 or 6) and the abutment face A.

3. Thermal switching device according to claim 1 or 2, characterised in that the contact extension (8, 9) protrudes downwards beyond the notional extension of the horizontal abutment face A.

4. Thermal switching device according to at least one of the preceding claims, characterised in that the contact extension (8, 9) has at least one upper-side end region (19, 20) which extends parallel with the connection (5, 6).

5. Thermal switching device according to at least one of the preceding claims, characterised in that the contact extension (8, 9) is secured in a non-releasable manner to the lower side of the connection (5 or 6).

6. Thermal switching device according to at least one of claims 1 to 4, characterised in that the contact extension (8, 9) is connected to the free end of the connection (5 or 6) in a releasable manner.

7. Thermal switching device according to at least one of the preceding claims, characterised in that the contact extension (8, 9) is constructed as a leaf spring.

8. Thermal switching device according to at least one of claims 1 to 4, characterised in that the contact extension (8, 9) can be fitted to the free end of the connection (5 or 6).

9. Thermal switching device according to claim 8, characterised in that the contact extension (8, 9) has bent-open receiving channels (21).

10. Thermal switching device according to at least one of claims 1 to 9, characterised in that the contact extension (8, 9) has along the vertical extent thereof an open C-like shape or closed shape.

11. Thermal switching device according to at least one of claims 1 to 4, characterised in that the contact extension (8, 9) is loosely in abutment both at the upper side and at the lower side and is fixed in the position thereof by means of a housing portion (22), preferably without any additional assembly step.

12. Thermal switching device according to at least one of the preceding claims, characterised in that the contact extension has a protuberance (13) at the end region thereof opposite the connection.

13. Thermal switching device according to at least one of claims 1 to 6 and 8 to 12, characterised in that the contact extension (8, 9) is constructed as a resilient contact pin.

14. Contact element for a thermal switching device, in particular temperature controller, temperature limiter, temperature monitor or thermal link, for connection to a heating device (14) of a utensil, wherein the thermal switching device is in thermal contact with the heating device (14), characterised in that the contact element is constructed as a resilient contact extension (8, 9) for the connection (5, 6) of the thermal switching device.

15. Contact element according to claim 14, characterised in that the resilient contact extension is constructed as a leaf spring.

16. Contact element according to claim 14 or 15, characterised in that the contact extension (8, 9) has at least one assembly region which is preferably constructed in a planar manner for securing the contact extension (8, 9) to the connection of the thermal switching device.

17. Contact element according to claim 16, characterised in that the assembly region is provided with a plug type receiving member.

18. Contact element according to claim 16, characterised in that bent-open receiving channels (21) are provided in the assembly region.

19. Contact element according to claims 13 to 18, characterised in that the contact extension (8, 9) has a contact region for contacting the thick-film heater.

20. Contact element according to claim 19, characterised in that the contact region of the contact extension (8, 9) has a protuberance (13, 14).

21. Contact element according to claims 14 to 20, characterised in that the contact extension (8, 9) has an open shape with one end region of the contact extension forming the assembly region and the other end region forming the contact region.

22. Contact element according to claims 14 to 20, characterised in that the contact extension (8, 9) has a closed shape with the two open end regions of the contact extension forming the contact region.

23. Contact element according to claims 14 to 22, characterised in that the contact extension (8, 9) has at least one, preferably a plurality of retention projections.

24. Contact element according to claim 23, characterised in that a retention wing (23, 24) which is provided on the leaf spring between the angled regions and which is orientated at an angle with respect to the leaf spring is provided as the retention projection.

25. Contact element according to claim 14, characterised in that the resilient contact extension is constructed as a resilient contact pin.