EP3484247B1 - Telescopic slide for a microwave oven - Google Patents

Description

The present invention relates to a telescopic rail with at least one first rail element made of an electrically conductive material and a second rail element made of an electrically conductive material, the first and the second rail element each having two running surfaces, with the two running surfaces of the first rail element being received in a rolling element cage Rolling bodies are arranged and on the two running surfaces of the second rail element are arranged rolling bodies received in a rolling body cage, and wherein the first and the second rail element can be moved relative to one another between a retracted position and an extended position along a pull-out direction.

Telescopic rails with at least two rail elements and a rolling element cage with rolling elements received therein for reducing the friction between the rail elements during an extension movement are known in various embodiments from the prior art. They are used in various household appliances but also in automotive engineering and in many other applications.

From the DE 10 2011 054 726 A1 For example, a metallic component for a fitting, in particular for an oven pull-out guide or a side grille for holding food carriers, is known, which is characterized in that the component has a sliding, corrosion-resistant composite layer which is temperature-resistant of more than 250 ° C, preferably more than 300 ° C.

In the DE 20 2009 001 962 U1 also describes a pull-out guide, in particular for household appliances with a guide rail and at least one additional rail, which are mounted on running surfaces via rolling elements so as to be displaceable relative to one another, and have at least one latching means to hold the additional rail in a predetermined position on the guide rail and / or a to releasably fix further additional rail, wherein the at least one latching means comprises a spring element which can be brought into engagement with a profiling or recess arranged at a distance from a running surface on a rail.

While a large number of areas of application can already be addressed with the known telescopic rails, telescopic rails have not yet established themselves in microwave ovens can. If you have a telescopic rail, the rail elements of which are made from an electrically conductive material, in particular from sheet metal, the microwave radiation impinging on the telescopic rail leads to local charging of the rail elements and a sufficiently large potential difference between the individual rail elements when the microwave oven is in operation a spark discharge between them.

In order to avoid a spark discharge, for example from the EP 2 988 068 A1 , Constructions are known in which the rail elements have a sufficiently large distance from one another due to the formation of sufficiently large and electrically insulating rolling bodies. However, these telescopic rails have a very large installation dimension.

There is therefore a need for a telescopic rail which at least partially avoids the aforementioned disadvantages.

Therefore, it is proposed according to the invention to design a telescopic rail of the type mentioned for a microwave oven in such a way that the first rail element has at least one electrically conductive contact element and the second rail element has at least one electrically conductive contact element, the contact element of the first rail element and the contact element of the second rail element are designed and arranged on the rail elements in such a way that in the retracted position either the contact element of the first rail element and the contact element of the second rail element are in engagement with one another or that the contact element of the first rail element and the contact element of the second rail element are each electrically moved with the rolling element cage conductive guide element are in engagement, so that in the retracted position there is an electrically conductive connection between the first and the second rail element, that in at least one other position than the retraction position, the contact element of the first rail element and the contact element of the second rail element are not in engagement with each other or at least the contact element of the first rail element or the contact element of the second rail element are not in engagement with the guide element, so that in the at least one other position the electrically conductive connection is interrupted and that at least the first rail element or the second rail element has two legs which form the running surfaces for the rolling elements and a connecting section connecting the two legs, the contact element being arranged on the connecting section.

What is decisive for the present invention is the knowledge that the mechanical engagement and thus the direct electrically conductive connection between the contact elements are only required in the inserted state. As a rule, microwave ovens can only be put into operation, that is to say that the electromagnetic microwave radiation can only then be transmitted to the telescopic rail can act when the door of the microwave oven is closed. A prerequisite for closing the door, however, is that the rail elements of the telescopic rail no longer protrude beyond the muffle of the microwave oven.

In the context of the present application, the retraction position is understood to mean the position of the first and second rail elements relative to one another in which the telescopic rail is completely inserted. Typically, the pull-in position is characterized by reaching an end stop.

The contact elements according to the invention do not provide any electrically conductive connection, at least in a position other than the retracted position, i.e. the electrically conductive connection is then interrupted.

An engagement between the contact element of the first rail element and the contact element of the second rail element is understood in the sense of the present application to mean a direct mechanical contact of their surfaces, which is such that an electric current can flow between the contact elements and over the point of engagement, ie over the point of contact between the two contact elements.

Surprisingly, it has been shown that the contact elements according to the invention in the retracted position can not only effectively prevent a spark between edges and tips of adjacent rail elements, but also a punctual current flow via the rolling elements of the telescopic rail. The latter proves to be particularly advantageous because punctual currents which flow via the contact points of the rolling elements with the running surfaces of the rail elements can lead to damage to the rolling elements and the running surfaces and, moreover, lubricants in the vicinity of the rolling elements can be destroyed by thermal influence .

For the realization of the advantages of the present invention it is necessary to effect a potential equalization of at least one rail element which is exposed to the microwave radiation. In this case, it is initially irrelevant whether the local charges that arise there flow off onto a directly adjacent rail element or another rail element. In the case of a full extension runner with three rail elements, the charges can alternatively flow onto the middle rail element or onto the inner rail element.

When speaking of a telescopic rail in the sense of the present application, this term is to be understood in such a general way that it not only includes rails in which the first rail element and the second rail element have approximately the same length, but also linear guides, in which the first rail element is significantly shorter than the second rail element.

If in the present application it is stated that the telescopic rail according to the invention has a first rail element and a second rail element, this does not rule out that the telescopic rail comprises further rail elements, in particular for providing a full extension.

A rolling element in the context of the present application is understood to mean a rotational body which, as an element of a guide, significantly reduces the friction between the various rail elements and thus facilitates a relative movement of two rails to one another. Rolling elements are, for example, balls, rollers, barrels, needles or cones.

In one embodiment of the present invention, the rolling elements are balls. It goes without saying that in this case the rolling element cage is a ball cage.

In one embodiment of the invention, the first rail element and the second rail element are made of a material that is selected from a group consisting of sheet steel, aluminized sheet steel and stainless steel.

In particular, in one embodiment of the invention, the rolling elements can be made from an electrically conductive material, for example steel.

It goes without saying that the contact elements are electrically conductively connected to the rail elements in order to be able to provide the potential equalization. In one embodiment, at least one of the contact elements is formed in one piece with the respective rail element.

In one embodiment, at least one of the contact elements is formed by a projection on the first or second rail element. It is useful if the projection has a greater extent in the pull-out direction than in a direction perpendicular to the pull-out direction. A larger extension of the projection in the pull-out direction than in a direction perpendicular to the pull-out direction ensures the function of the contact elements even if the telescopic rail is not fully retracted, i.e. in the retracted position.

This is particularly advantageous if, in one embodiment of the invention, the length of the telescopic rail in the extension direction is dimensioned so that even after a door of a household appliance in which the telescopic rail is installed has been closed, the telescopic rail is not fixed in exactly one position, but rather the two rail elements can be arranged in a range of positions relative to one another. Then it is important to ensure electrical contact between the two rail elements across this area.

Such an elongated projection in the extension direction can, in particular when fully extended, also be arranged on a central rail element which allows only a small size of the projection in the area of its connecting section.

In one embodiment of the invention, the projection is designed as an impression of a sheet metal material of the respective rail element. Such beads can be produced inexpensively in a simple manner.

In a further embodiment of the invention, the contact element of the first rail element is formed by a projection and the contact element of the second rail element is formed by a projection, the projection on the first rail element being larger in the extension direction than in a direction perpendicular to the extension direction and wherein the projection on the second rail element has a smaller extension in the extension direction than in the direction perpendicular to the extension direction.

Elongated projections as contact elements that are arranged crossed to one another on the two rail elements are able to compensate for the tolerances of the profiles of the rail elements and of that for assembly. In one embodiment, the tolerance chain to be taken into account also includes the dimensions of the installation space of a household appliance, in particular the muffle of a microwave oven, and the door that closes it.

In one embodiment of the invention, the telescopic rail provides a full extension, the telescopic rail having two outer rail elements and a central rail element, and the projection being provided on the central rail element with a greater extension in the extension direction than the extension in the direction perpendicular to the extension direction.

In one embodiment of the invention, the contact elements are exclusively in the retracted position, i.e. when the end stop is reached, either with one another or both with the guide element.

In a further embodiment, the contact elements are in the retracted position and over a partially extended area in the vicinity of the retracted position with each other or both are in engagement with the guide element, the length of the area in the extension direction over which the contact elements with each other in the partially extended state in Are engagement, is predetermined by an expansion and / or a position of the contact elements on the rail elements in the pull-out direction.

This ensures that equipotential bonding takes place between the rail elements even when the telescopic rail is almost but not completely pushed in.

Regardless of the need for the two rail elements to be connected to one another in an electrically conductive manner when the telescopic rail is completely pushed in or almost completely pushed in, it has been shown that the location of the electrical contact can be selected between the contact elements of the first rail element and the second rail element viewed in the extension direction of the telescopic rail so that it is associated with advantages.

It has been shown that arcing between the rail elements typically occurs at their ends, since on the one hand there are edges and points here, but on the other hand the rail elements can also come relatively close spatially at the ends.

Therefore, in one embodiment of the invention, the contact element of the first rail element and the contact element of the second rail element are arranged and configured such that in the retracted position the location of engagement between the contact element of the first rail element and the contact element of the second rail element or the location of engagement between the Contact element of a rail element with the guide element at a distance of 50 mm or less measured in the extension direction, preferably at a distance of 40 mm or less and particularly preferably at a distance of 30 mm or less from one end of a rail element.

In one embodiment, the location of engagement between the contact element of the first rail element and the contact element of the second rail element or the location of engagement between the contact element of a rail element with the guide element is also in the retracted position at a distance of 5 mm or more measured in the extension direction of the end of a rail element.

Surprisingly, not only the choice of the position of the electrical contact between the contact elements in the retracted position in the area of the ends of the rail elements leads to advantages, but also an arrangement of the electrical contact in the area in which the ball cage is in the retracted position. An engagement between the contact elements at a position in an area in which the ball cage is in the retracted position leads to currents through the balls being reduced to such an extent that no damage is caused to the elements of the telescopic rail.

Therefore, in one embodiment of the invention, the contact element of the first rail element and the contact element of the second rail element are arranged and designed in such a way that in the retracted position the location of engagement between the contact element of the first rail element and the contact element of the second rail element or the location of engagement between a Contact element and the guide element lies in the pull-out direction in an area in which the ball cage is located.

It can be sufficient if, in one embodiment of the invention, the first rail element and the second rail element each have a contact element which are in engagement with one another in the retracted position. In this case, an electrically conductive connection between the first rail element and the second rail element is provided at precisely one position in the extension direction of the telescopic rail when the telescopic rail is pushed in.

However, it is also conceivable that a plurality of contact elements are provided after the first rail element and a plurality of contact elements are provided on the second rail element, which are in electrically conductive engagement with one another in the retracted position. Potential equalization then takes place at a plurality of positions in the extension direction of the telescopic rail.

In one embodiment of the invention, the first rail element has three contact elements and the second rail element has three contact elements which are in engagement with one another in the retracted position, two of the contact elements of each rail element being provided at the ends of the respective rail element and one contact element in the middle of each Rail element is provided. In this way, sparks at the ends of the rail elements can be avoided and a current flow via the rolling elements in the middle of the rail elements can be reduced.

In one embodiment of the invention, the telescopic rail is a full extension runner with two outer rail elements and a central rail element arranged between the two outer rail elements, the two outer rail elements each having at least one contact element and the central rail element having at least two contact elements, so that in the retracted position a Contact elements of the outer rail element is either in engagement with a contact element of the middle rail element or a contact element of an outer rail element and a contact element of the middle rail element are each in engagement with an electrically conductive guide element moved with the rolling element cage, so that in the retracted position there is an electrically conductive connection between two outer rail elements and the middle rail element.

In a further embodiment, at least the first or the second rail element has an electrical insulation at one end thereof, which is designed such that the insulation is arranged in the retracted position in a possible spark gap between the first and the second rail element. By arranging an electrical insulator, ie a dielectric, between the rail elements or between sections of the rail elements, the dielectric strength is increased and the probability of a spark discharge is increased decreased. Such an embodiment is particularly useful when the contact elements are provided exclusively in an area in which the rolling element cage is arranged in the retracted position.

In addition to embodiments of the present invention in which the contact elements of the first and second rail elements are in direct electrically conductive engagement with one another in the retracted position, the solution according to the invention also includes embodiments in which each of the contact elements of the first or second rail element is connected to the rolling element cage moved electrically conductive guide element are in engagement, but are not in direct engagement with one another. Such an embodiment has the advantage that the material of the guide element can be made thinner and thus more flexible than the material of the rail elements themselves. This optimizes the electrical contact between the contact elements of the rail elements and the guide element and thus between the first and second rail elements.

In one embodiment of the invention, the guide element is formed by the rolling element cage itself.

One of the above-mentioned objects is also achieved by a microwave oven with a telescopic rail in an embodiment thereof, as described above.

In one embodiment of the invention, the lengths of the rail elements of the telescopic rail are selected such that, when the door of the microwave oven is closed, it is in the retracted position or in an only partially extended position. In this way, closing the door of the microwave oven also ensures electrically conductive contact between the contact elements and thus potential equalization between the rail elements.

Therefore, in one embodiment of the invention, the microwave oven has an oven muffle and a door for closing the oven muffle, the door being movable between a position closing the oven muffle and a position releasing the oven muffle. The telescopic rail is built into the furnace muffle in such a way that when the door is in the position releasing the furnace muffle, the first rail element or the second rail element can be brought into the pull-out position so that the first rail element or the second rail element protrudes from the furnace muffle. Furthermore, at least a length of the first rail element or a length of the second rail element in the extension direction are selected in such a way and the contact element of the first rail element and the contact element of the second rail element arranged and designed such that when the door is in the position that closes the furnace muffle, the contact element of the first rail element and the contact element of the second rail element are forced into engagement with each other or the contact element of the first rail element and the contact element of the second rail element each with the the rolling element cage with moving electrically conductive guide element into engagement, so that there is an electrically conductive connection between the first and the second rail element.

In one embodiment of the invention, the door or the telescopic rail of the microwave oven has an elastic part which, when the door is in the worn position of the oven muffle, is arranged between the door and one end of the first and / or second rail element.

In one embodiment of the invention, the elastic part is attached to one end of the first rail element or the second rail element. Alternatively or additionally, an elastic part can be attached to the door of the furnace itself.

In one embodiment of the invention, the elastic part is an elastic molded part made from silicone.

Figur 1

ist eine schematische Draufsicht auf einen Mikrowellenofen gemäß einer Ausführungsform der vorliegenden Erfindung.

Figur 2

ist eine perspektivische, weggebrochene Ansicht einer Ausführungsform der erfindungsgemäßen Teleskopschiene.

Figur 3

ist eine schematische Querschnittsansicht einer alternativen Ausführungsform der erfindungsgemäßen Teleskopschiene.

In a further embodiment, the elastic part is dimensioned such that it is in engagement with the door and the telescopic rail when the door is in the position that closes the furnace muffle. In particular, in one embodiment, the part is then elastically deformed.
Further advantages, features and possible applications of the present invention will become clear on the basis of the following description of an embodiment and the associated figures.

Figure 1

Fig. 3 is a schematic plan view of a microwave oven according to an embodiment of the present invention.

Figure 2

Figure 3 is a perspective, broken away view of one embodiment of the telescopic slide of the present invention.

Figure 3

is a schematic cross-sectional view of an alternative embodiment of the telescopic rail according to the invention.

In the figures, the same elements are denoted by the same reference symbols.

Figure 1 shows a microwave oven 1 with two telescopic rails 2 according to the invention, which are each connected to a side wall 3 of the muffle 4 of the oven 1. The telescopic rails 2 are fully extendable with three rail elements 5, 6, 7.

During the operation of the microwave oven 1, the telescopic rails 2, but in particular the internal rail elements 5, are exposed to the microwave radiation of the oven. This electromagnetic radiation leads to a local electrostatic charge in the rail elements 5. This charge in turn can lead to arcing in the area of the ends 8, 9 of the rail elements 5, 6, 7.

In addition, between the rail elements 5, 6, 7 of the telescopic rails 2 ball cages with bearing balls arranged therein (in Figure 1 not shown), which serve to guide the individual rail elements 5, 6, 7 relative to one another. The electrostatic charging of the rail elements 5, 6, 7 can also lead to currents flowing away via the bearing balls. Because of the point-like contact of the bearing balls with the running surfaces of the rail elements 5, 6, 7, high currents can arise which lead to damage either to the ball or to the running surfaces.

In order to prevent the local electrostatic charging, in particular of the rail element 5, the telescopic rails 2 each provide an electrically conductive connection at the three positions marked with arrows along the extension direction 10 of the telescopic rail 2.

In an open position of the door 11 ′, the rail elements 5, 6 can be pulled out through the opening of the muffle 4.

The microwave oven 1 can, however, only be put into operation when the door 11 is closed. In other words, the rail elements 5 can only be electrostatically charged when the door 11 is closed. It is therefore sufficient if the equipotential bonding is only possible in the retracted position of the telescopic rails 2 shown.

Therefore, in the in Figure 1 The embodiment shown, the lengths of the rail elements 5, 6, 7 in the pull-out direction 10 are dimensioned so that when the door 11 is closed, the rail elements are essentially in the retracted position. Furthermore, the contact elements of the first rail element 5 and the contact elements of the second rail element 6 are arranged and configured in such a way that when the door 11 is closed, the contact elements of the first rail element 5 and the contact elements of the second rail element 6 are forced into engagement with one another, so that an electrically conductive There is a connection between the first and the second rail element 5, 6.

In order to be able to compensate for the comparatively long chain of tolerances consisting of the tolerances of the door 11, 11 'and their fastening, the muffle 4 and the telescopic rails and their assembly, at the end 9 of the first, inner rail element 5 facing the opening of the muffle 4, a Silicone molded part 30 arranged. In the closed state of the door 11, this extends between the door 11 and the end 9 of the inner rail element 5. The silicone molded part 30 is dimensioned such that it engages with the door 11 and, if necessary, is elastically deformed by the latter.

Figure 2 FIG. 12 shows a broken away perspective view of the telescopic rail 2 from FIG Figure 1 . It can be clearly seen that the telescopic rail 2 has two outer rail elements 5, 7 and a central rail element 6, which together form a full extension. In the feed position, which is also in Figure 2 is shown, the outer rail element 5 and the middle rail element 6 are electrically conductively connected to one another. In the context of the present application, the outer rail element 5 forms a first rail element and the middle rail element 6 forms a second rail element.

Each of the first and second rail elements 5, 6 has two legs 12, 13, each of which is shown in the illustration Figure 2 only one of the legs 12, 13 is shown. The legs 12, 13 form the raceways for receiving the bearing balls between the rail elements 5, 6, 7. The two legs 12, 13 of a rail element are in turn connected to one another via connecting sections 14, 15 of the rail elements 5, 6.

In order to provide the necessary potential equalization in the retracted position, the connecting sections 14, 15 of both rail elements 5, 6 are provided with indentations or beads 16, 17. These beads 16, 17 form projections 18, 19 on the other side of the sheet metal material of the rail elements 5, 6, which protrude from the surfaces 20, 21 of the connecting sections 14, 15 of the rail elements 5, 6. These projections 18, 19 on the connecting sections 14, 15 of the rail elements 5 6 form contact elements within the meaning of the present application.

The projections 18, 19 are designed in such a way that they are only in mechanical engagement with one another in the retracted position. If the rail elements 5, 6, 7 are pulled out, the projections 17, 18 are out of engagement. However, only the mechanical engagement provides an electrically conductive connection between the first rail element 5 and the second rail element 6.

In the embodiment shown, the bead 16 and thus the projection 18 on the first rail element 5 has an extension in the extension direction 10 of the telescopic rail 2, which is less than the extension of the bead 16 and thus the projection 18 in the direction perpendicular to the extension direction 10 . In contrast to this, the bead 17 and thus the projection 19 on the second rail element 6 has an extension in the extension direction 10 which is greater than the extension of this projection in the direction perpendicular to the extension direction 10.

This crossed arrangement of the projections 17, 18 enables a certain compensation of the tolerances of the rail elements and the assembly of the rail elements 5, 6, 7. In particular, however, the extended longitudinal extension in the extension direction 10 of the projection 19 enables the projections 18, 19 to engage over an area away. The conductive connection between the projections 18, 19 is therefore provided as contact elements not only in the pull-in position defined by the end stop, but also in an area in the vicinity of the pull-in position.

At the end of the inner rail element 7, an electrical insulator 28 is also arranged, which is located between the middle rail element 6 and the inner rail element 7 in the retracted position. The insulator 28 is therefore located in a possible spark gap between the middle rail element 6 and the inner rail element 7 and prevents sparking between the rail elements 6, 7.

The electrically conductive connection between the first and the second rail element 5, 6 is made in the embodiment of the telescopic rail 2 Figure 2 provided by a direct mechanical engagement between the two projections 18, 19 of the rail elements 5, 6. In contrast to this, the electrical connection of two rail elements 5 ', 6' or 6 ', 7' is provided via the ball cages 26, 27 arranged between the contact elements 22, 23 and 24, 25.

In this embodiment of a telescopic rail 2 ′ according to the invention, the contact elements 22, 23 are in engagement with the first ball cage 27 as a guide element in the sense of the present application in the retracted position. The contact elements 24, 25 are in engagement with the second ball cage 26 in the retracted position.

It should be noted that in the embodiment shown, the engagement between the contact elements 23 on the second rail element 6 'and the ball cage 27 on the one hand and the engagement between the contact elements 22 on the first rail element 5' and the ball cage 27 on the other hand in a direction perpendicular to Extension direction 10 takes place at different positions. In this way, the spring property of the ball cage 27 can be used, in order to ensure an improved electrical contact between the contact elements 22, 23 and the ball cage 27.

For the purposes of the original disclosure, it is pointed out that all features as they can be understood from the present description, the drawings and the claims for a person skilled in the art.

While the invention has been illustrated and described in detail in the drawings and the foregoing description, this illustration and description is merely exemplary and is not intended to limit the scope of protection as it is defined by the claims. The invention is not limited to the disclosed embodiments. Modifications of the disclosed embodiments will be apparent to those skilled in the art from the drawings, the description and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "a" does not exclude a plurality. Reference signs in the claims are not intended to limit the scope of protection.

List of reference symbols

1

Microwave oven

2, 2 '

Telescopic rail

3

Side wall

4th

Grouch

5, 5 ', 6, 6' 7, 7 '

Rail element

8, 9

Ends of the rail elements 5, 6, 7

10

Extension direction

11, 11 '

door

12, 13

leg

14, 15

Connection section

16, 17

Bead

18, 19

head Start

20.21

surface

22, 23, 24, 25

Contact element

26.27

Ball cage

28

insulator

29

Bearing ball

30th

Silicone molding

Claims (14)

1. A telescopic slide (2, 2') for a microwave oven (1), having
   at least one first slide element (5, 5') produced from an electrically conductive material and
   a second slide element (6, 6') produced from an electrically conductive material,
   wherein the first and the second slide elements (5, 5', 6, 6') each have two running surfaces,
   wherein rolling bodies (29) received in a rolling body cage (26, 27) are disposed on the two running surfaces of the first slide element (5, 5') and rolling bodies (29) received in a rolling body cage (26, 27) are disposed on the two running surfaces of the second slide element (6, 6'), and wherein the first and the second slide elements (5, 5', 6, 6') can be moved against each other between a retracted position and an extended position along an extension direction (10),
   characterized in that
   the first slide element (5, 5') has at least one electrically conductive contact element (18, 22) and the second slide element (6, 6') has at least one electrically conductive contact element (19, 23),
   wherein the contact element (18, 22) of the first slide element (5, 5') and the contact element (19, 23) of the second slide element (6, 6') are configured and disposed on the slide elements (5, 5', 6, 6') in such a manner that in the retracted position, either the contact element (18) of the first slide element (5) and the contact element (19) of the second slide element (6) are in engagement with each other, or the contact element (22) of the first slide element (5') and the contact element (23) of the second slide element (6') are each in engagement with an electrically conducting conductive element that is moved concomitantly with the rolling body cage (26), such that in the retracted position, there is an electrically conducting connection between the first and the second slide elements (5, 5', 6, 6'), in that in at least one position other than the retracted position, the contact element (18) of the first slide element (5) and the contact element (19) of the second slide element (6) are not in engagement with each other or at least the contact element (22) of the first slide element (5') or the contact element (23) of the second slide element (6') is not in engagement with the conductive element, such that in the at least one other position, the electrically conducting connection is interrupted, and in that at least the first slide element (5, 5') or the second slide element (6, 6') has two limbs (12, 13), which form the running surfaces for the rolling bodies (29), and a connecting portion (14, 15) connecting the two limbs (12, 13), wherein the contact element (18, 19, 22, 23) is disposed on the connecting portion (14, 15).
2. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that at least one of the contact elements (18, 19, 22, 23, 24, 25) is formed by a protrusion on the first or the second slide element (5, 5', 6, 6').
3. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that at least one protrusion (18) has a greater extent in the extension direction (10) than in a direction perpendicular to the extension direction (10).
4. The telescopic slide (2, 2') according to claim 2 or claim 3, characterized in that the protrusion is formed as an indentation (16, 17) of a sheet metal material of the respective slide element (5, 6).
5. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that the contact element of the first slide element (5) is formed by a protrusion (18) and the contact element of the second slide element (6) is formed by a protrusion (19), wherein the protrusion (18) on the first slide element (5) has a greater extent in the extension direction (10) than in a direction perpendicular to the extension direction (10), and wherein the protrusion (19) on the second slide element (6) has a smaller extent in the extension direction (10) than in the direction perpendicular to the extension direction (10).
6. The telescopic slide (2, 2') according to the preceding claim, characterized in that it has two outer slide elements (5, 7) and a middle slide element (6), wherein the protrusion (19) with the extent that is greater in the extension direction (10) than the extent in the direction perpendicular to the extension direction (10) is provided on the middle slide element (6).
7. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that the contact elements (18, 19, 22, 23, 24, 25) are in engagement with each other or are both in engagement with the conductive element exclusively in the retracted position.
8. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that the contact elements (18, 19) are in engagement with each other or are both in engagement with the conductive element in the retracted position and in the extended position (10), starting from the retracted position, over a range of positions outside the retracted position, wherein the length of the region in the extension direction (10) is predetermined by an extent and/or a position of the contact elements (18, 19) on the slide elements (5, 6) in the extension direction (10).
9. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that the contact element (18) of the first slide element (5) and the contact element (19) of the second slide element (6) are disposed and configured in a manner such that in the retracted position, the position of the engagement between the contact element (18) of the first slide element (5) and the contact element (19) of the second slide element (6) in the extension direction (10) lies in a region in which the ball cage is located.
10. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that the telescopic slide (2, 2') has two outer slide elements (5, 7) and a middle slide element (6) disposed between the two outer slide elements (5, 7), wherein the two outer slide elements (5, 7) each have at least one contact element (18) and the middle slide element (6) has at least two contact elements (19) such that in the retracted position, either a contact element (18) of each outer slide element (5, 7) is respectively in engagement with a contact element (19) of the middle slide element (6), or a contact element of an outer slide element and a contact element of the middle slide element are respectively in engagement with an electrically conducting conductive element that is moved concomitantly with a rolling body cage, such that in the retracted position there is an electrically conducting connection between the outer slide elements and the middle slide element.
11. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that at least the first or the second slide element (5, 6), at an end (8, 9) thereof, has an insulation (28) which is configured in a manner such that in the retracted position it is disposed in a possible spark gap between the first and the second slide element (5, 6).
12. The telescopic slide (2, 2') according to one of the preceding claims, characterized in that the conductive element is a portion of the rolling body cage.
13. A microwave oven (1) with a telescopic slide (2, 2') according to one of the preceding claims.
14. The microwave oven (1) according to claim 13, characterized in that the microwave oven (1) has an oven compartment (4) and a door (11, 11') for closing the oven compartment (4), wherein the telescopic slide (2, 2') is built into the oven compartment (4) in a manner such that when the door (11, 11') is in a position which exposes the oven compartment (4), the first slide element (5, 5') or the second slide element (6, 6') can be brought into the extended position so that the first slide element (5, 5') or the second slide element (6, 6') protrudes out of the oven compartment (4), and wherein at least one length of the first slide element (5, 5') or one length of the second slide element (6, 6') in the extension direction (10) is selected, and the contact element (18) of the first slide element (5) and the contact element (19) of the second slide element (6) are disposed and configured, in a manner such that when the door (11, 11') is in a position that closes the oven compartment (4), the contact element (18) of the first slide element (5) and the contact element (19) of the second slide element (6) are inevitably in engagement with each other, or the contact element (22) of the first slide element (5') and the contact element (23) of the second slide element (6') are respectively in engagement with the electrically conducting conductive element which is moved concomitantly with the rolling body cage (26) such that there is an electrically conducting connection between the first and the second slide elements (5, 5', 6, 6').

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