EP3972387A1 - Telescopic rail - Google Patents

Abstract

The present invention relates to a telescopic rail for a microwave oven with at least a first rail element and a second rail element made of an electrically conductive material, the first and the second rail element being slidably mounted on one another in such a way that the second rail element is between a retracted position and a retracted position relative to the first rail element Pull-out position can be moved in and against a pull-out direction. It is proposed to design such a telescopic rail in such a way that a spacer element made of an electrically insulating material is arranged at least on a front end of the second rail element in the extension direction, with the spacer element extending from the second rail element in the extension direction, or between the in a spacer element made of an electrically insulating material is arranged at the front end of the second rail element in the pull-out direction and at a front end of the first rail element in the pull-out direction, the spacer element being arranged in such a way that the spacer element is at a distance from the front end of the second rail element when the second rail element is in the retracted position Rail member defined by the front end of the first rail member.

Description

The present invention relates to a telescopic rail for a microwave oven with at least a first rail element and a second rail element made of an electrically conductive material, the first and the second rail element being slidably mounted on one another in such a way that the second rail element is between a retracted position and a retracted position relative to the first rail element Pull-out position can be moved in and against a pull-out direction.

Telescopic rails with at least two rail elements and optionally a rolling element cage with rolling elements accommodated therein to reduce the friction between the rail elements during an extension movement are known in a variety of embodiments from the prior art. They are used in various household appliances, but also in automobile construction and in many other applications.

While a large number of areas of application can already be addressed with the known telescopic rails, telescopic rails have not yet been able to establish themselves in microwave ovens. If you have a telescopic rail whose rail elements are made of an electrically conductive material, in particular sheet metal, the microwave radiation impinging on the telescopic rail leads to local charging of the rail elements during operation of the microwave oven and, if there is a sufficiently large potential difference between the individual rail elements and the environment to a spark discharge between the elements of the telescopic rail and an element of the microwave oven, for example the door. This can lead to the destruction or at least damage to part of the microwave oven.

Therefore, there is a need for a telescopic slide which effectively avoids spark discharge between the telescopic slide and a part of the microwave oven.

According to the invention it is proposed to design a telescopic rail of the type mentioned for a microwave oven in such a way that at least one front in the pull-out direction end of the second rail element, a spacer element made of an electrically insulating material is arranged, with the spacer element extending from the second rail element in the pull-out direction, or between the front end of the second rail element in the pull-out direction and a front end of the first rail element in the pull-out direction Spacer element is arranged from an electrically insulating material, wherein the spacer element is arranged such that the spacer element defines a distance of the front end of the second rail element from the front end of the first rail element in the retracted position of the second rail element.

The present invention is based on the idea of always, i.e. necessarily, having a sufficiently large distance between the metallic, i.e. electrically conductive elements of the telescopic rail and the door of the microwave oven, at least with an electrically non-conductive spacer element between the front end of the second rail element and the door of the microwave oven Microwave oven to ensure that a spark discharge is not possible or at least the probability of a spark discharge is reduced or with an electrically non-conductive spacer element between the front end of the second rail element and the front end of the first rail element always, ie necessarily, a sufficiently large distance between the front ends of the first and second rail members so that spark discharge is not possible or at least the likelihood of spark discharge between the rail members is reduced.

In this case, the front end of the first rail element in the pull-out direction is that end which points towards the opening of the oven muffle of the microwave oven when the telescopic rail is installed. Furthermore, the front end of the second rail element in the pull-out direction is that end which points towards the opening of the oven muffle of the microwave oven when the telescopic rail is installed

For the purposes of the present application, the retracted position is understood to be the position of the first and second rail elements relative to one another, in which the telescopic rail is fully inserted. Typically, the retraction position is characterized by reaching an end stop.

If, within the meaning of the present application, a telescopic rail is mentioned, this term is to be understood in such a general way that not only rails are included in which the first rail element and the second rail element have approximately the same length, but also linear guides, in which the second rail element is significantly shorter than the first rail element.

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

In one embodiment of the invention, the first and the second rail element each have two running surfaces, with rolling elements held in a rolling element cage being arranged on the two running surfaces of the first rail element and rolling elements held in a rolling element cage being arranged on the two running surfaces of the second rail element.

A rolling body in the sense of the present application is understood to mean a rotating 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 particular, in one embodiment of the invention, the rolling bodies can be made of an electrically conductive material, for example steel.

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, at least the second rail element is made of a material selected from a group consisting of sheet steel, aluminized sheet steel and stainless steel. In one embodiment of the invention, the first and second rail elements, but in particular all rail elements of the telescopic rail, are made from such an electrically conductive material.

In one embodiment of the invention, the electrically insulating material of the spacer element and/or the spacer element is selected from a group consisting of silicone, PEEK, wood or a ceramic material.

In one embodiment of the invention, the electrically insulating material is a high-temperature resistant material, in particular a material which can withstand temperatures of 200° C. or more, preferably 300° C. or more and particularly preferably 500° C. or more without damage or material change. The advantage of such a material is that it can be used in a microwave oven with a pyrolysis function for the pyrolytic self-cleaning of the microwave oven. Examples of such high temperature resistant materials are PEEK and a ceramic material.

In one embodiment of the invention, the ceramic material is a metal oxide ceramic, preferably comprising at least one aluminum oxide ceramic or one zirconium oxide ceramic. In one embodiment of the invention, the ceramic material is a mixture of an alumina ceramic and a zirconia ceramic. In a further embodiment, the aluminum oxide ceramic content in such a mixture is between 20% and 80%.

Spacer elements and spacer elements made of metal oxide ceramics, in particular aluminum oxide ceramics and/or zirconium oxide ceramics, can be produced in many different shapes with the aid of ceramic injection molding. The material has the advantage that it is also resistant to impulse mechanical stress and has a sufficiently smooth surface to avoid damage when the microwave oven door is engaged. The latter is particularly useful when the spacer element engages with the door when the door is closed and then slides over the surface of the door due to the geometry of the door that is hinged on one side.

In one embodiment of the invention, the spacer element extends, starting from the electrically conductive material of the second rail element, over at least 3 mm, preferably over at least 5 mm in the pull-out direction. This extension of the spacer element in the pull-out direction determines the minimum distance that must be maintained between the rail elements and the door of the microwave oven. A distance of at least 3 mm between the door of the microwave oven and the electrically conductive material of the second rail element effectively reduces the likelihood of spark discharge between these elements. With a distance of at least 5 mm, such a spark discharge is largely impossible for most microwave ovens.

In one embodiment of the invention, the spacer element extends between the first end of the second rail element and the first end of the first rail element over at least 3 mm, preferably over at least 5 mm in the pull-out direction. This extent of the spacer element in the pull-out direction determines the minimum distance between the first rail element and the second rail element that must be maintained. A distance of at least 3mm between the conductive edges of the first and second rail members effectively reduces the likelihood of arcing between these members. With a distance of at least 5 mm, such a spark discharge is largely impossible for most microwave ovens.

There are a number of partially alternative embodiments for realizing the spacer element and/or the spacer element.

In one embodiment of the invention, the telescopic rail has both a spacer element and a spacer element. In a further embodiment, the spacer element and the spacer element are designed in one piece. In such an embodiment, in particular, a single molded body forms both the spacer element and the spacer element.

On telescopic rails for ovens, in particular for microwave ovens, lugs are usually provided at the front end in the extension direction, ie pointing towards the opening of the oven, which on the one hand form a termination of the telescopic rail at the front, but on the other hand protrude over the telescopic rail in the vertical direction , so that the tab serves as a stop for a food support placed on the telescopic rail, so that the telescopic rail can be pulled out of the oven by gripping the food support, for example a baking tray, since the food support engages behind the tab.

In one embodiment of the invention, the spacer element and/or the spacer element is an end cap made of the electrically insulating material, the end cap being connected to the second rail element at the front end in the pull-out direction. In this embodiment, the end cap made of electrically insulating material replaces the tab made of electrically conductive material as provided in the prior art. In one embodiment, the end cap also extends from the front end of the second rail element in the opposite direction to the pull-out direction, so that the end cap forms the spacer element. In one embodiment of the invention, the end cap made of the electrically insulating material forms both the spacer element and the spacer element.

For the purposes of the present application, the vertical direction is understood to mean a direction perpendicular to the pull-out direction, which in the installed state extends essentially parallel to the wall of the furnace muffle to which the telescopic rail is connected.

In one embodiment of the invention, the end cap, as a spacer element and/or spacer element, has an extension in the vertical direction of the telescopic rail that is greater than the extension of the second rail element in the vertical direction. In this way, the spacer element projects in the vertical direction relative to the second rail element.

In further embodiments of the present invention, the spacer element is arranged in addition to a preferably electrically conductive lug at the front end of the second rail element, with the spacer element extending from the lug in the pull-out direction, so that it can fulfill its spacer function with respect to the door.

The extension of the spacer element in the pull-out direction over at least 3 mm, preferably at least 5 mm, is measured in such an embodiment in relation to the front surface of the tab made of the electrically conductive material pointing towards the opening of the oven.

In an embodiment of the present invention, the spacer element is arranged in addition to a preferably electrically conductive tab at the front end of the second rail element, with the spacer element extending from the tab in the opposite direction to the pull-out direction, so that it can fulfill its spacer function with respect to the first rail element.

The extension of the spacer element from the tab against the pull-out direction over at least 3 mm, preferably at least 5 mm, is measured in such an embodiment in relation to the back surface of the tab made of the electrically conductive material pointing away from the opening of the oven.

In one embodiment of the invention, the tab has a front surface pointing in the pull-out direction, with the spacer element completely covering the front surface. Such a complete covering means that a dielectric is completely provided between the door of the oven and the rail element, which makes a spark discharge less likely.

In one embodiment, the spacer element covers the front surface only in sections. Due to the distance function of the spacer element, even covering only in sections causes a significant reduction in the probability of a spark discharge. In addition, only partial coverage of the front face of the tab makes it possible to reduce the amount of material used for the spacer element.

Particularly in the case of a spacer element and/or a spacer element made of a ceramic material, it is only possible to a limited extent to form the spacer element and/or the spacer element in any desired shape. The spacer element and/or the spacer element preferably has a rotational symmetry, for example a cylindrical basic shape, in particular if it is made of a ceramic material. Such forms have a high stability and are also easy to produce from ceramic material using ceramic injection molding.

In one embodiment of the invention, the spacer element and/or the spacer element is connected to the respective rail element in a non-positive, positive or material connection, in particular to the lug of the second rail element, or by means of a combination of a force connection, a form connection or a material connection.

In one embodiment of the invention, the spacer element and/or the spacer element is glued onto the tab made of the electrically conductive material or is glued into a recess in the tab.

In one embodiment of the invention, the spacer element has a formed external thread, the external thread being screwed into an internal thread introduced into the bracket. An external thread can be formed on a spacer element in such a way that the thread consists of the same material as the rest of the spacer element, i.e. the thread is an integral part of the spacer element. Such a spacer element with an external thread can be produced in particular from a ceramic material by injection molding. In one embodiment of the invention, the external thread of the spacer element extends through the tab in such a way that the portion of the material with the external thread forms a spacer element within the meaning of the present application.

In one embodiment of the invention, the spacer element and/or the spacer element has an opening, in particular a hole, with a fastening means, for example a screw, reaching through the opening and engaging with the lug, preferably a thread of the lug.

In a further embodiment of the invention, the tab made of the electrically conductive material has at least one latching lug and the spacer element and/or the spacer element has at least one latching recess, the latching lug and the latching recess being arranged in such a way that the latching lug is latched into the latching recess . In one embodiment of the invention, the spacer element and/or the spacer element has a cylindrical section which engages in an opening in the tab made of the electrically conductive material, the latching depression being formed on the cylindrical section in the form of a groove extending in the circumferential direction. The detent is then a projection provided in the circumferential direction on the side walls of the recess of the tab made of the electrically conductive material. This projection snaps into the groove as a detent. In one embodiment of the invention, the tab has a plurality of latching lugs, for example three or four latching lugs.

In a further embodiment of the present invention, the spacer element encompasses the tab made of the electrically conductive material at least in sections in the manner of a covering cap.

In one embodiment of the present invention, the first rail element has at least one electrically conductive contact element and the second rail element also has an electrically conductive contact element, the contact element of the first rail element and the contact element of the second rail element being 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 in engagement with an electrically conductive guide element that is moved along with a rolling element cage, so that in the retracted position there is an electrically conductive connection between the first and the second rail element and that the contact element is in at least one position other than the retracted position of the first rail element and the contact element of the second rail element are not in engagement with one another, 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 the electrically conductive connection is interrupted in the at least one other position. An electrically conductive connection between the first rail element and the second rail element in the retracted position causes potential equalization in the event of possible charging of the second rail element by the electromagnetic radiation of the microwave oven and thus reduces the probability of a spark discharge.

In such an embodiment, the spacer element brings about a forced displacement of the second rail element relative to the first rail element into the retracted position and thus forced electrical contact between the first and the second rail element for potential equalization.

This embodiment is based on the idea that the mechanical engagement and thus the direct electrically conductive connection between the contact elements of the first rail element and the second rail element are required in the inserted state, ie the retracted position. Microwave ovens can usually only be put into operation, ie the electromagnetic microwave radiation can only act on the telescopic rail when the door of the microwave oven is closed. However, closing the door presupposes that the rail elements of the telescopic rail no longer project beyond the muffle of the microwave oven.

At least in a position other than the retracted position, the contact elements do not provide an electrically conductive connection, i.e. the electrically conductive connection is then interrupted.

For the purposes of the present application, an engagement between the contact element of the first rail element and the contact element of the second rail element is understood to mean direct mechanical contact between their surfaces, which is such that an electric current flows between the contact elements and via the point of intervention, i.e. via the point of contact between the two contact elements, can flow.

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

In order to realize the advantages of the present invention, it is necessary to bring about a potential equalization of at least one rail element which is exposed to the microwave radiation. It is initially irrelevant whether the local charges that have arisen there flow off onto an immediately adjacent rail element or another rail element. In the case of a full extension with three rail elements, the charges can alternatively flow to the middle rail element or to the inner rail element.

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 expedient here if the projection has a greater extent in the pull-out direction than in a direction perpendicular to the pull-out direction. A greater extension of the projection in the extension direction than in a direction perpendicular to the extension direction ensures the function of the contact elements even when the telescopic rail is not fully retracted, ie is 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 such that even after a door of a household appliance in which the telescopic rail is installed is closed, the telescopic rail is not fixed in exactly one position, but the two rail members can be arranged in a range of positions relative to each other. Then it is important to ensure electrical contact between the two rail elements across this area.

Such an elongated projection in the pull-out direction can also be arranged on a central rail element, which only allows for a small overall size of the projection in the region of its connecting section, in particular in the case of a full extension.

In one embodiment of the invention, the projection is designed as an embossing 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 having a greater extension in the pull-out direction than in a direction perpendicular to the pull-out direction and wherein the projection on the second rail element has a smaller extent in the pull-out direction than in the direction perpendicular to the pull-out direction.

Longitudinally extended projections arranged crossed with respect to one another on the two rail elements as contact elements are able to compensate for the tolerances of the profiles of the rail elements and of the 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 full extension, with the telescopic rail having two outer rail elements and a central rail element, and with the projection having a greater extent in the extension direction than the extent in the direction perpendicular to the extension direction on the central rail element.

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

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

This ensures that potential equalization between the rail elements also takes place when the telescopic rail is almost, but not completely, pushed in.

In addition to embodiments of the present invention, in which the contact elements of the first and second rail element 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 a roller body cage moved along with the electrically conductive conducting element are engaged, 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 therefore 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 the second rail element. In one embodiment of the invention, the guide element is formed by the rolling element cage itself.

At least one of the objects mentioned above is also achieved by a microwave oven with a telescopic rail in embodiments such as those described above. In one embodiment, the microwave oven includes a source of microwave radiation having a frequency of about 2.4 GHz.

A microwave oven within the meaning of the present invention is understood to be any oven or any cooking appliance which has a source of microwave radiation. For example, a combi oven with a microwave function is a microwave oven within the meaning of the present invention.

In particular, at least one of the objects mentioned above is also achieved by a microwave oven with pyrolysis for self-cleaning. In one embodiment, the microwave oven therefore has a heating device for heating the oven muffle to a temperature of 200° C. or more, preferably 300° C. or more, and particularly preferably 500° C. or more.

In one embodiment of the invention, the lengths of the rail elements of the telescopic rail in the extension direction and the extension of the spacer element in the extension direction are selected such that the telescopic rail is in the retracted position or in an only partially extended position when the door of the microwave oven is closed. In this way, closing the door of the microwave oven ensures a sufficiently large distance, caused by the spacer element, between the electrically conductive second rail element and the door of the microwave oven. In one embodiment of the invention, this choice of dimensions in the pull-out direction also ensures an electrically conductive contact between the contact elements and thus potential equalization between the rail elements.

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 oven muffle in such a way that when the door is in the position releasing the oven muffle, the second rail element can be brought into the pulled-out position, so that the second rail element protrudes from the oven muffle.

In one embodiment of the invention, a door-side spacer element made of the electrically insulating material is provided on the door. The door-side spacer element is arranged in such a way that after the door is closed, the door-side spacer element extends between the material of the door and the front end of the second rail element. The door-side spacer element can be provided as an alternative or in addition to the spacer element at the front end of the second rail element.

Furthermore, in one embodiment, at least one length of the first rail element or one length of the second rail element in the extension direction and the extension of the spacer element at the front end of the second rail element and/or the extension of the door-side spacer element in the extension direction are selected such that when the door is in the position that closes the furnace muffle, the telescopic rail is forced to be in the retracted position.

Figur 1

ist eine teilweise weggebrochene isometrische Darstellung von vorne einer ersten Ausführungsform des Distanzelements.

Figur 2

ist eine teilweise weggebrochene isometrische Ansicht von hinten des Distanzelements aus Figur 1.

Figur 3

ist eine teilweise weggebrochene isometrische Darstellung von vorne einer weiteren Ausführungsform des Distanzelements.

Figur 4

ist eine teilweise weggebrochene isometrische Darstellung von hinten des Distanzelements aus Figur 3.

Figur 5

ist eine weggebrochene isometrische Darstellung von vorne einer weiteren Ausführungsform des Distanzelements.

Figur 6

ist eine Querschnittsansicht in Auszugsrichtung des Distanzelements aus Figur 5.

Figur 7

ist eine teilweise weggebrochene isometrische Darstellung von vorne einer weiteren Ausführungsform des Distanzelements.

Figur 8

ist eine teilweise weggebrochene isometrische Darstellung von hinten des Distanzelements aus Figur 7.

Figur 9

ist eine teilweise weggebrochene isometrische Darstellung von vorne einer weiteren Ausführungsform des Distanzelements.

Figur 10

ist eine teilweise weggebrochene Schnittansicht des Distanzelements aus Figur 9.

Figur 11

ist eine schematische Darstellung von oben eines Mikrowellenofens mit einer Ausführungsform der Teleskopschiene.

Figur 12

ist eine teilweise weggebrochene isometrische Darstellung einer Ausführungsform der Teleskopschiene.

Figur 13

ist eine teilweise weggebrochene Seitenansicht der Teleskopschiene aus Figur 12.

Figur 14

ist eine teilweise weggebrochene isometrische Darstellung einer weiteren Ausführungsform der Teleskopschiene.

Figur 15

ist eine teilweise weggebrochene Seitenansicht der Teleskopschiene aus Figur 14.

Further advantages, features and possible applications of the present invention become clear from the following description of an embodiment and the associated figures. In the figures, the same elements are denoted by the same reference symbols.

figure 1

Figure 13 is a partially broken away front isometric view of a first embodiment of the spacer.

figure 2

Figure 12 is a partially broken isometric rear view of the spacer figure 1 .

figure 3

Figure 12 is a front isometric view, partially broken away, of another embodiment of the spacer element.

figure 4

Figure 12 is a partially broken away rear isometric view of the spacer figure 3 .

figure 5

Figure 12 is a front, broken-away isometric view of another embodiment of the spacer.

figure 6

12 is a cross-sectional view in the pull-out direction of the spacer figure 5 .

figure 7

Figure 12 is a front isometric view, partially broken away, of another embodiment of the spacer element.

figure 8

Figure 12 is a partially broken away rear isometric view of the spacer figure 7 .

figure 9

Figure 12 is a front isometric view, partially broken away, of another embodiment of the spacer element.

figure 10

12 is a partially broken sectional view of the spacer of FIG figure 9 .

figure 11

Fig. 12 is a schematic representation from above of a microwave oven with an embodiment of the telescopic rail.

figure 12

12 is an isometric view, partially broken away, of one embodiment of the telescoping slide.

figure 13

12 is a side view, partially broken away, of the telescopic rail of FIG figure 12 .

figure 14

12 is an isometric view, partially broken away, of another embodiment of the telescopic rail.

figure 15

12 is a side view, partially broken away, of the telescopic rail of FIG figure 14 .

In all the specific embodiments described with reference to the figures, the spacer element 4 is made of a ceramic material, namely an aluminum oxide ceramic with a zirconium content of 15%. Such a ceramic material can be produced in a variety of shapes by ceramic injection molding and has a smooth surface with a low coefficient of friction.

The telescopic rail 3 is shown in all of the Figures 1 to 10 shown broken away. Each of the telescopic rails 3 forms a full extension with three rail elements 1 , 2 , 7 . The stationary rail element connected or connectable to the furnace muffle is referred to as the first rail element 1 . The rail element, which can be completely pulled out of the furnace muffle, is referred to as the second rail element 2 in the sense of the language used in the present application. In the case of a full extension, there is also a third, central rail element 7, which is only visible in the schematic top view figure 11 you can see. In addition, between the rail elements 1, 2, 7 of the telescopic rails 3 are ball cages with bearing balls arranged therein (not shown in the figures), which serve to guide the individual rail elements 1, 2, 7 relative to one another.

figure 11 shows a microwave oven 13 with two telescopic rails 3 according to the invention, which are each connected to a side wall 14 of the muffle 15 of the oven 13. During the operation of the microwave oven 13, the telescopic rails 3, but in particular the inner, second rail elements 2, are exposed to the microwave radiation of the oven. This electromagnetic radiation leads to a local electrostatic charge in the rail elements 2 . This charging in turn can lead to a spark discharge between the rail elements 1, 2, 7 and the door 12' in the closed state if there is not a sufficient distance between the rail elements 1, 2, 7 and the door 12'.

When the door 12 is in an open position, the rail elements 2, 7 can be pulled out of the muffle 15 through the opening. However, the microwave oven 13 can only be put into operation when the door 12' is closed. In other words, the rail elements 1, 2, 7 can only be electrostatically charged when the door 12' is closed.

Therefore, in all in the Figures 1 to 11 In the embodiments shown, the lengths of the rail elements 1, 2, 7 in the extension direction 5 and the extension E of the spacer element 4 in the extension direction 5 are dimensioned such that when the door 12' is closed, the rail elements are essentially in the retracted position.

In order to reduce the local electrostatic charging of the rail element 2 in particular, the telescopic rails 3 also provide an electrically conductive connection between the first and second rail elements when the telescopic rail 3 is in the retracted position.

In the embodiment of Figures 1 and 2 the spacer element 4 is designed in the form of an end cap on the front end 6 of the second rail element 2 of the telescopic rail 3 in the extension direction 5 .

The end cap 4 has an extension E in the pull-out direction 5, so that the minimum distance between an end face 11 of the second rail element and the door 12, 12' of the microwave oven 13 is 5 mm.

The end cap 4 replaces the tab provided in the prior art on the front end 6 in the pull-out direction 5 on the second rail element 2 . The end cap 4 has a projection U in the vertical direction 10 in relation to an upper edge of the second rail element 2 . The spacer element 4 thus also acts as a stop for a food carrier placed on the second rail element 2 .

On the rail side, the end cap 4 has a fastening section 9 which is oversized in the vertical direction 10 so that the fastening section 9 is clamped in a non-positive manner between the running surfaces 8 of the second rail element 2 .

In the embodiment of Figures 1 and 2 the spacer element 4 completely replaces the metal tab otherwise provided on the second rail element. In contrast, all other embodiments shown here have the Figures 3 to 10 a tab 17 made of metal provided at the front end 6 of the second rail element 2 . This tab is bent from the material of the back of the rail 6 of the second rail element 2 . The tab 17 provides an overhang in relation to the upper edge of the second rail element 2 in order to form a boundary for the food support placed on the second rail element 2 .

The extent of the spacer element in the pull-out direction, starting from the second rail element 2, is in the embodiments of FIG Figures 3 to 10 measured from a front face 19 of the tab 17. In all embodiments, the extension of the ceramic spacer element 4 from the front surface 19 of the tab 17 is 5 mm.

In the embodiment of Figures 3 and 4 the spacer element 4 is a cuboid which is glued into a bead 18 in the tab 17 of the second rail element 2 .

The embodiments of Figures 5 to 10 is common that the spacer element 4 has a substantially cylindrical basic shape. Such basic cylindrical shapes can be produced simply and inexpensively with the aid of ceramic injection molding. In addition, such shaped bodies made of ceramic are extremely stable, even with respect to punctiform mechanical stress.

The other embodiments of Figures 5 to 10 have compared to the material connection of the spacer element 4 with the tab 17 from the Figures 3 and 4 a positive connection between the spacer element 4 and the tab 17.

In the embodiment of Figures 5 and 6 the spacer element 4 has a cylindrical receiving section 20 with an external thread 21 formed therein. The spacer element 4 with the cylindrical receiving section 20 is made entirely and in one piece from the ceramic material. The external thread 21 is screwed into an internal thread 22 arranged in a hole in the bracket 17 .

In the embodiment of Figures 7 and 8 the cylindrical lateral surface 24 of the spacer element 4 has a locking recess in the form of a circumferential groove in the lateral surface 24 of the spacer element 4 . The cylindrical base body of the spacer element 4 is pushed into a hole 26 in the lug 17 . The wall surface of the hole has four latching lugs 27, which extend in the radial direction, so that the hole in this area is smaller than the outer diameter of the lateral surface 24 of the spacer element 4. The latching lugs 27 therefore engage in a form-fitting manner in the groove 25 in the lateral surface 24 of the spacer element 4 and effectively hold the spacer element 4 on the tab 17.

While the embodiments of Figures 5 and 6 on the one hand as well as the Figures 7 and 8 on the other hand, both do without an additional fastener is in the embodiment of Figures 9 and 10 a fastener in the form of a screw 23 is provided. This screw 23 reaches through a hole 28 in the spacer element 4 . The screw is screwed into an internal thread 22 of the lug 17 .

The embodiments of Figures 12 to 15 differ from the previously described embodiments in that they all have a spacer element 29 in addition to the spacer element 4 . Like the spacer element 4, the spacer element 29 consists of an electrically insulating ceramic material. The spacer element 29 serves to provide a sufficient distance between the metallic tab 17 arranged at the front end 6 of the second rail element 2 and the front end 30 of the first rail element 1 . Because of the spacer element 29, there is a probability of a spark flashover between the tab 17 and the front end 30 of the first rail element 1 is significantly reduced.

the end figure 13 it can be seen that the spacer element 29 is provided in addition to a spacer element 4 between the tab 17 and the closed door 12 of the furnace muffle. The functioning of the spacer element 4 is the same as before for the embodiments of FIG Figures 1 to 11 described. In the embodiment of Figures 12 and 13 Both the spacer element 29 and the spacer element 4 are glued to the tab 17, ie bonded to it.

While in the embodiments of Figures 12 to 15 the spacer element 29 is provided in addition to the spacer element 4, embodiments are conceivable in which the telescopic rail 3 has only a spacer element 29, but not a spacer element 4. In addition, it is also conceivable that the spacer element 4 is arranged on the door 12 of the furnace muffle instead of on the front end 6 of the second rail element. Furthermore, embodiments are conceivable in which the spacer element consists of a first spacer element 4, which is mounted on the front end 6 of the second rail element 2, and a door-side spacer element (not shown in the figures), which is attached to the door 12 of the oven muffle is.

In contrast, the Figures 14 and 15 an embodiment in which the spacer element 4 and the spacer element 29 are designed in one piece as a single molded body made of ceramic material. It replaces in this embodiment Figures 14 and 15 the spacer element 4 has the tab 17. The spacer element 4 is inserted or clamped into the second rail element 2 with the aid of a clamping block, this clamping block also forming the spacer element 29 at the same time.

For the purposes of the original disclosure, it is pointed out that all the features that are apparent to a person skilled in the art from the present description, the drawings and the claims, even if they were specifically described only in connection with certain other features, both individually and in any combinations can be combined with other features or groups of features disclosed here, unless this has been expressly excluded or technical circumstances make such combinations impossible or pointless. The comprehensive, explicit representation of all conceivable feature combinations is omitted here only for the sake of brevity and legibility of the description.

While the invention has been illustrated and described in detail in the drawings and the foregoing description, this illustration and description is by way of example only and is not intended to limit the scope of protection as defined by the claims. The invention is not limited to the disclosed embodiments.

Modifications to the disclosed embodiments will become apparent to those skilled in the art from the drawings, the specification, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plural. The mere fact that certain features are claimed in different claims does not preclude their combination. Reference signs in the claims are not intended to limit the scope.

Reference List

1

first rail element

2

second rail element

3

telescopic rail

4

spacer element

5

pull direction

6

front end of the second rail element

7

third (middle) rail element

8th

Running surfaces of the second rail element 2

9

Fastening section of the spacer element 4

10

vertical direction

11

Face of the second rail element 2

12,12'

door

13

microwave oven

14

Side wall

15

muffle

16

rail back

17

tab

18

bead

19

Front face of tab 17

20

attachment section

21

external thread

22

inner thread

23

screw

24

lateral surface

15

groove

26

Hole in tab 17

27

detent

28

Hole in the spacer 4

29

spacer element

30

front end of the first rail element

E

Extension of the spacer element in the pull-out direction

Claims (15)

Telescopic rail (3) for a microwave oven () with at least one first rail element (1) and a second rail element (2) made of an electrically conductive material, wherein the first and the second rail element (1, 2) are slidably mounted on one another in such a way that the second rail element (2) can be moved between a retracted position and an extended position relative to the first rail element (1). are displaceable in and against a pull-out direction (5),
characterized in that A spacer element (4) made of an electrically insulating material is arranged at least on one end (6) of the second rail element (2) that is at the front in the pull-out sighting (5), the spacer element (4) extending from the second rail element (2) in the Extension direction (5) extends, or A spacer element (29) made of an electrically insulating material is arranged between the front end (6) of the second rail element in the pull-out direction (5) and a front end (30) of the first rail element (1) in the pull-out direction (5), the Spacer element (29) is arranged such that the spacer element (29) in the retracted position of the second rail element (2) has a distance between the front end (6) of the second rail element (2) and the front end (30) of the first rail element (1) Are defined. Telescopic rail (3) according to the preceding claim, in which the electrically insulating material is a ceramic material. Telescopic rail (3) according to the preceding claim, wherein the ceramic material is a metal oxide ceramic, preferably a metal oxide ceramic with a mixture of an aluminum oxide ceramic and a zirconium oxide ceramic. Telescopic rail (3) according to one of the preceding claims, wherein at least the spacer element (4), starting from the electrically conductive material of the second rail element (2), extends over at least 3 mm, preferably over at least 5 mm in the pull-out direction (5), or the Spacer element (29) between the front end (6) of the second rail element (2) and the first end (30) of the first rail element (1) over at least 3 mm, preferably over at least 5 mm in the pull-out direction (5). Telescopic rail (3) according to one of the preceding claims, in which the spacer element (4) and/or the spacer element (29) is an end cap made from the electrically insulating material, the end cap on the front end (6) in the extension direction (5) is connected to the second rail element (2). Telescopic rail (3) according to one of the preceding claims, wherein the second rail element (2) has a tab (17) made of an electrically conductive material at the front end (6), the spacer element (4) starting from the tab (17). extends in the pull-out direction (5) and/or the spacer element (29) extends from the tab (17) counter to the pull-out direction (5). Telescopic rail (3) according to claim 6, wherein the tab (17) made of the electrically conductive material has a front surface (19) pointing in the extension direction (5), the spacer element (4) covering the front surface (19) only in sections. Telescopic rail (3) according to Claim 6 or 7, in which the spacer element (4) and/or the spacer element (29) has an external thread (21) formed from the material of the spacer element, the external thread (21) being inserted into a hole in the tab (17 ) introduced from the electrically conductive material internal thread (22) is screwed. Telescopic rail (3) according to claim 6 or 7, wherein the spacer element (4) and/or the spacer element (29) has an opening (28), with a fastening means, preferably a screw (23), reaching through the opening (28) and is in engagement with the tab (17) made of the electrically conductive material, preferably an internal thread (22) of the tab (17). Telescopic rail (3) according to claim 6 or 7, wherein the tab (17) made of the electrically conductive material has a latching lug (27) and the spacer element (4) and/or the spacer element (29) has a latching depression (25), the The latching lug (27) and the latching recess (25) are arranged in such a way that the latching lug (27) is engaged in the latching recess (25). Telescopic rail (3) according to one of the preceding claims, wherein the spacer element (4) and the spacer element (29) are designed in one piece. Telescopic rail (3) according to Claim 6, in which the spacer element (4) encompasses the tab (17) made of the electrically conductive material at least in sections in the manner of a covering cap. Microwave oven (13) with a telescopic rail (3) according to one of the preceding claims, wherein the microwave oven (13) has an oven muffle (15) and a door (12, 12') for closing the oven muffle (15), the telescopic rail (3 ) is installed in the furnace muffle (15) in such a way that when the door (12) is in a position releasing the furnace muffle (15), the second rail element (2) can be brought into the pulled-out position, so that the second rail element (2 ) protrudes from the furnace muffle (15). Microwave oven (13) according to claim 13, wherein a door-side spacer element made of the electrically insulating material is provided on the door (12, 12') and wherein the door-side spacer element is arranged in such a way that the door-side spacer element is between the door (12, 12' ) and the front end (6) of the second rail element (2) when the door (12, 12') is in a position closing the furnace muffle (15). Microwave oven (13) according to Claim 13 or 14, in which the microwave oven (13) has an oven muffle (15) and a door (12, 12') for closing the oven muffle (15), the telescopic rail (3) being inserted into the oven muffle ( 15) is installed so that when the door (12) is in a position releasing the oven muffle (15), the second rail element (2) can be brought into the pulled-out position, so that the second rail element (2) can be removed from the oven muffle (15 ) protrudes, wherein the first rail element (1) and the second rail element (2) are designed in such a way and at least the spacer element (4) at the front end (6) of the second rail element (2) or the door-side spacer element is arranged and designed in such a way, that when the door (12') is in a position closing the furnace muffle (15), the telescopic rail (3) is forced into the retracted position.

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