WO2018059951A2

WO2018059951A2 - Expansion joint for a household appliance with an axial bearing for a rolling body and household appliance

Info

Publication number: WO2018059951A2
Application number: PCT/EP2017/073117
Authority: WO
Inventors: Philipp Nather; Angelika Namberger; Karsten Pörner
Original assignee: BSH Hausgeräte GmbH
Priority date: 2016-09-28
Filing date: 2017-09-14
Publication date: 2018-04-05
Also published as: WO2018059951A3; DE102016218737A1

Abstract

The invention relates to a expansion joint (7) for a household appliance (1), comprising a first rail (8) and a separate second rail (9) which is connected to the first rail (8). The rails (8, 9) can be displaced in a displacement direction in the direction of the longitudinal axis (L) relative to each other by means of a rolling body device (12). Said rolling body device (12) comprises a rolling cage (11) in which at least one rolling body (14, 23) is rotationally mounted, said rolling body (14, 23) comprises an axle bearing (15, 39) which is arranged on the rolling body cage (11) and the rolling bodies (14, 23) comprise a running element (16, 35) which is arranged so as to rotate about the axle bearing (15, 39), the running element (16, 35) is arranged in a recess (17) of the rolling body cage (11) and at a distance to the defining walls (19, 20, 21, 22) of the recess (17). The invention relates to a household appliance (1) having at least one expansion joint (7).

Description

Rail extension device for a household appliance with an axle bearing for a rolling element and household appliance

The invention relates to a rail extension device for a household appliance with a first rail and a separate second rail, which is connected to the first rail. The rails are in the direction of their longitudinal axes in one

Displacement direction relative to each other by means of a Wälzkörpervorrichtung displaced. The Wälzkörpervorrichtung comprises a separate from the rails Wälzkörperkäfig, in which at least one rolling element is rotatably mounted. Furthermore, the invention also relates to a household appliance with at least one such rail extension device.

Rail extension devices in the form of so-called telescopic extensions are well known. In such embodiments, the two elongated rails, which usually have substantially equal lengths, are correspondingly extendable and collapsible. On such rail extension devices are at

Household appliances for preparing food, such as a cooking appliance, food support, such as a baking tray, or a drip tray or a grid applied, so that they can be easily pulled out of a cooking chamber of the cooking appliance and pushed back into it. It is also known in the context that these two rails are mounted on rolling elements, such as balls, slidably to each other. The case provided ball cage, for example, takes only the position control of the balls on corresponding recesses and is otherwise considered force and effect free with respect to the rolling elements. The

The weight of the food carrier is transmitted directly from one rail to the other via these balls. In addition to the almost pure rolling motion of the rolling elements on the tracks of the rails, however, the balls grind directly on the ball cage during rolling. This can lead to tilting of the cage and consequently also to a bucking and a hook of the pull-out rail. If the system is smeared with a lubricant, especially a grease, these become unwanted

However, friction effects are significantly reduced. However, in these embodiments, a significant disadvantage is the fact that these lubricants for high

Temperatures, such as those in a pyrolysis of a named Cooking device may not be suitable. In rail extension devices for household appliances for preparing food, which also have a pyrolysis, so only a dry lubrication makes sense. In addition, at

Embodiments with an above-mentioned lubricant requires a sufficient amount of this lubricant in order to actually be able to significantly reduce these frictional effects. This in turn has disadvantages for the rail extension device to the effect that it is then not dishwasher-safe, because at a

Washing process in the dishwasher, this lubricant is then washed out.

This results in running restrictions of the rails to each other.

From DE 199 49 239 A1 a pull-out device for a food support in

Garraum of Garöfen known in which the Wälzkörpervorrichtung roles than

Has rolling elements. It is an object of the present invention to provide a rail extension device and a household appliance, in which the running action of the rails is improved to each other.

This object is achieved by a rail extension device and a household appliance according to the independent claims.

An inventive rail extension device for a household appliance comprises a first rail and a separate second rail, which is connected to the first rail. The two rails are elongated, beam-shaped components and one of the two rails has a length of between 80 percent and 100 percent of the length of the other rail. In particular, the two rails are essentially the same length. The rails are displaceable relative to one another in the direction of their longitudinal axes and thus also in the direction of a longitudinal axis of the rail extension device by means of a roller body device separate from the rails in a displacement direction. The rolling element device comprises a rolling element cage which is a component separate from the rails. In the Wälzkörperkäfig at least one rolling element is rotatably mounted. An essential idea of the invention is the fact that the rolling element has an axle bearing, which in particular also the axis of rotation of the rolling element includes. This axle bearing is arranged on the Wälzkörperkäfig. The rolling element further comprises a running element, which is formed around the axle bearing around, in particular is formed rotationally symmetrical about the axis of rotation around. This running element is arranged revolving around the axis of rotation, wherein the

Running element is arranged in a recess in the rolling element cage and spaced from the boundary walls of this recess is arranged. By this configuration, an axial guidance of a rolling element is possible and beyond that is the

Running element always spaced and non-contact on boundary walls of the

Recess stored in Wälzkörperkäfig. Unwanted contacts of the rolling element of the rolling element with components of the rolling element cage during a rolling movement of the running element are thus avoided. Also, this is a particularly straightforward

Running direction of the running element achieved. The rolling element is thus stable, positionally accurate and easily arranged in the Wälzkörperkäfig, which is essential

Improvements in running performance and beyond, in particular, lubricant can be significantly reduced or even no longer needed. This also has significant advantages with regard to the use of such

Rail extension device in household appliances for preparing food, which have a pyrolysis, so that the rail extension device and durable temperatures, for example, over 500 ° C, withstand without losing their functionality. In addition, such rail extension devices are now also significantly improved dishwasher suitable, since a washing out of lubricants is substantially reduced or completely prevented.

It is preferably provided that the rolling element cage is C-shaped in a cross section perpendicular to a longitudinal axis of the rail extension device. This configuration is very torsionally stiff and thus contributes to the high level of smoothness of the rails to each other as well as the high smoothness of the rolling elements on the

Roller cage. This allows a very jam-free and low-spreading as well as directional motion control. In particular, the first rail extends through a belly of the C-shape.

In particular, it is provided that in an upper free leg of the C-shape, a first recess is formed, in which a first rolling element with a first Axial bearing is mounted, and in a lower free leg of the C-shape, a second recess is formed, in which a second rolling element is mounted with a second axis bearing. The Wälzkörperkäfig is thus on the one hand in its specific shape for improved reception of a rail, in particular the first rail, formed, and thus there is a contacting of this first rail, each with a rolling element from above and from below. A particularly rectified and continuous smooth motion control is thereby made possible. An undesirable tilting or spreading of the components relative to one another is therefore prevented. It is preferably provided that a first running element, in particular with an uneven running surface, of the first rolling body rests against an outer side of the first rail formed as a first raceway and a second running element, in particular with an uneven running surface, of the second rolling body forms a second running track outside bottom of the first rail is applied. The rolling elements of the rolling elements are therefore formed so that their provided with the raceways contact surfaces have a curvature, in particular a specific arc shape, with which they come into contact with tracks at specific locations of the first rail. Such a configuration can be a very individual

Shaping the contacting area between a running element and a raceway can be achieved and thereby improved running performance can be achieved. This in particular to the effect that in the displacement direction the straightness can be achieved particularly advantageous.

In a particularly advantageous manner, it is provided that the first rail on a outside upper side has a first raceway, which is uneven.

In particular, this unevenness is specified by a groove shape. Especially with such a configuration, a running shape of a rolling element of the rolling element is then virtually created a complementary shape between these uneven contact surfaces at a corresponding uneven configuration, whereby a particularly accurate tracking of the running element is achieved in the raceway. An undesired lateral displacement of the running element on the raceway is thereby prevented. In addition or instead of this, it is preferably provided that the first rail has on an outside underside a second raceway, which is uneven, in particular channel-shaped. Again, then the corresponding benefits apply. It is preferably provided that the second rail has on a top side inside a first raceway, which is uneven, in particular channel-shaped. This inside top is one of the first rails facing top. In addition or instead of this, it is preferably provided that the second rail has on an inside underside a second track, which is uneven, in particular channel-shaped. This underside is arranged facing the first rail. Also by these embodiments, when contacting rolling elements of rolling elements, the advantages already mentioned above can be achieved and even improved in connection with the above-mentioned advantageous embodiments.

In particular, it is provided that a first race element, in particular with an uneven running surface, of the first rolling body bears against the first raceway of the first rail and on the first raceway of the second rail. Additionally or instead, it is provided that a second running element, in particular with an uneven running surface, of the second rolling body bears against the second raceway of the first rail and on the second raceway of the second rail. Each running element thus contacts at least one respective raceway of the first rail and the second rail. As a result, the rails are held in particular position in relation to each other and allows the shifting in the direction of displacement in a particularly straight line.

In a further very advantageous embodiment, it is provided that the rolling body cage is arranged with its rolling elements relatively movable to the first rail and relatively movable to the second rail between these two rails. This also means that with a relative movement of the two rails and the

Rolling cage moved relative to these two rails in the direction of displacement.

In particular, this is the case when the rolling elements of the rolling elements are contacted both with a track of the first rail and each with a track of the second rail. Preferably, it is provided that the two rails are hollow, in particular groove-like, executed and are guided into each other, wherein the rolling element cage in a

Space between the rails is arranged. The groove-like shape is especially designed as C-shape or U-shape. This also means that such a rail is not circulating in a cross section perpendicular to its longitudinal axis

is closed, but is interrupted accordingly or is open.

Preferably, it is provided that an axis bearing in a direction different from the direction of displacement of the rails relative to each other to the rolling element cage

is slidably mounted. In particular, it is provided that this direction is oriented perpendicular to the direction of displacement. As a result, tolerances can be compensated and always a contact of a running element of a rolling element can be maintained with a career. For this purpose, for example, be provided that the

Axial bearing is arranged or stored in a slot of Wälzkörperkäfigs. As a result, the running elements can also carry out, for example in the case of impurities in the running region, a vertical deflecting movement and thus an evasive movement perpendicular to the displacement direction, without forcing forces on the shaft

To exert Wälzkörperkäfig and thus not on the Wälzkörperträger of

Exercise Wälzkörperkäfigs.

It is advantageously provided that several, in particular at least three, first rolling elements in a first row parallel to the longitudinal axis of the

Rail extension device are arranged on the Wälzkörperkäfig and a plurality, in particular three, second rolling elements are arranged in a parallel to the first row oriented second row and parallel to the longitudinal axis of the rail extension device on the Wälzkörperkäfig. The further improvement of the running effect

especially with regard to straight-line shifting is thereby increased again.

It is preferably provided that the running element is a roller. This is then axially guided with this axle bearing, but has no contact with any boundary walls of a recess of the Wälzkörperkäfigs. Likewise, that can

Running element also be, for example, an axle bearing ball. By the invention or an advantageous embodiment in particular of

Axial bearing and non-contact axial guidance of a rolling element to the rolling element or the entire Wälzkörperkäfig grinding operations and braking operations of the rolling element can be avoided on Wälzkörperkäfig. There are no forces acting on the Wälzkörperkäfig, so that an undesirable tilting or tilting of the Wälzkörperkäfigs is avoided relative to the rails. In particular, this is also additionally advantageously supported if the raceways and / or running surfaces of the rolling elements of the rolling elements are uneven in a cross section perpendicular to a longitudinal axis of the rail extension device.

Another independent aspect of the invention relates to a rail extension device for a household appliance, having a first rail and a separate second rail, which is connected to the first rail, wherein the rails in the direction of their longitudinal axes relative to each other by means of a Wälzkörpervorrichtung in a

Displacement direction are displaced, wherein the Wälzkörpervorrichtung a

Rolling body cage, in which at least one rolling element is rotatably arranged. The rolling element cage has a limited by boundary walls recess in which the rolling elements is arranged rotatably and with a formed in the direction of the longitudinal axes of the rails game. In a limited by the game end position of the rolling element in the recess of the rolling elements with a to a running surface of the rolling element, which is designed to contact a track of a rail, different contact surface of the rolling body with a

Bounding wall of the recess contacted and arranged with the tread contactless to all boundary walls of the recess.

Also by this embodiment, the tilting of the Wälzkörpervorrichtung about an axis perpendicular to the longitudinal axis of the rails and thus in the direction of displacement of the rails to each other is at least reduced. In particular, two separate contact surfaces are provided which are symmetrical to the longitudinal axis of the rail extension device, which is parallel to the longitudinal axes of the rails, and each contact with a boundary wall when the end position of the game is reached. In this further aspect of the invention, the rolling elements have no stationary

Axial storage, but can move as a whole relative to the Wälzkörperkäfig and indeed in the direction of the longitudinal axes of the rails, which is also the

Longitudinal axis of the rail extension device corresponds. Nevertheless, it is prevented that the rolling elements contacted with its tread the boundary wall, so that a strong tilting is avoided.

In particular, the game is limited so that a connecting line between

Contact points of the contact surfaces of the rolling element with the boundary walls, which runs perpendicular to the longitudinal axis of the rail extension device, is arranged close to the axis to a perpendicular to this longitudinal axis oriented center axis or axis of symmetry of the rolling body. In particular, one is in the direction of the longitudinal axis

dimensioned distance between the connecting line and the center axis smaller a dimensioned in this direction distance between the center axis and a running surface of the rolling body. In particular, this distance is less than or equal to half of this distance between the center axis and the tread.

In particular, the running surface is viewed in the direction of the connecting line formed between two contact surfaces of the rolling body.

In particular, the contact surfaces and the tread are formed without overlapping.

Preferably, the boundary walls are arranged obliquely to the longitudinal axis.

In particular, the boundary walls are arranged such that they form a rhombus in a plane in which the longitudinal axis of the rail extension device and the connecting line extend. It is also prevented that the rolling elements in this diamond-shaped recess with its tread to the front or the rear

Diamond border abuts. Furthermore, the invention also relates to a household appliance, in particular for

Preparing food, with at least one rail extraction device according to the invention or an advantageous embodiment thereof. The household appliance is designed in particular as a cooking appliance. The household appliance comprises in particular a Reception room for preparing food, which is in particular a cooking chamber, in which at least one such rail extension device is arranged and in

Depth direction of the household appliance is extendable and collapsible. On such a rail extension device, a food support such as a dripping pan, a grid or a baking sheet can be arranged in order to apply the food to it.

The terms "top", "bottom", "front", "rear", "horizontal", "vertical", "depth direction", "width direction", "height direction", etc. are the intended use and intended arrangement of the device and at a given then before the device standing and looking in the direction of the device given positions and orientations.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures, are not only in the respectively indicated combination but also in others

Combinations usable, without departing from the scope of the invention. There are thus also embodiments of the invention as encompassed and disclosed, which are not explicitly shown and explained in the figures, but by separated

Feature combinations emerge from the described embodiments and can be generated. Embodiments and combinations of features are also to be regarded as disclosed, which thus do not have all the features of an originally formulated independent claim. Moreover, embodiments and combinations of features, in particular by the embodiments set out above, are to be regarded as disclosed, which go beyond or deviate from the combinations of features set out in the back references of the claims.

Embodiments of the invention are described below with reference to schematic

Drawings explained in more detail. Show it:

Fig. 1 is a schematic perspective view of an embodiment of a household appliance according to the invention; FIG. 2 shows a partial perspective view of an embodiment of the rail extraction device according to the invention; FIG.

Fig. 3 is a perspective view of subcomponents of

Rail extension device according to FIG. 2;

4 is a plan view of a portion of the Wälzkörperkäfigs of FIG. 3.

Fig. 5 is a perspective sectional view along the section line V-V in Fig. 2; and

Fig. 6 is a plan view of another embodiment of a Wäklzkörperkäfigs.

In the figures, the same or functionally identical elements are the same

Provided with reference numerals.

In Fig. 1 a household appliance 1 is shown in a simplified perspective view, which is designed for preparing food and is for example a cooking appliance. The household appliance 1 comprises a housing 2, in which a cooking chamber 3 is formed which is bounded by walls of a muffle 4. In addition, the household appliance 1 comprises a door 5, which is designed to close the cooking chamber 3 and is pivotally mounted on the housing 2. In design and location to be understood merely as an example, an operating and / or display device 6 is present.

On opposite vertical side walls 4a and 4b of the muffle 4 a plurality of rail extension devices 7, one of which is explained in more detail below, arranged.

The rail extension devices 7 are arranged in pairs opposite each other at the same elevations along a height direction (y-direction), so that in this way also insertion levels are defined. On these paired assigned

Rail extension devices 7, a food support, such as a grid or a fat pan or a baking tray can be placed and thus in the depth direction (z- Direction) are pushed into the cooking chamber 3 or pulled out of the cooking chamber 3.

In Fig. 1 is a schematic representation of an embodiment of a

Rail extension device 7 shown. In the embodiment shown, the rail extension device 7 comprises a first rail 8 and a rail 9 separate therefrom

Rail extension device 7 has a longitudinal axis L, which is also the longitudinal axis of the two rails 8 and 9. The two rails 8 and 9 are in the direction of this longitudinal axis, by which a displacement direction is defined, relative to each other displaceable. The two rails 8 and 9 are substantially the same length

or one of the two rails is formed with a length between 80 percent and 100 percent of the length of the other rail. The second rail 9 represents an outer rail, which forms the running rail. The first rail 8 is an inner rail and constitutes a fixed rail, which means that it is fixed to the inside of the side wall 4a.

The second rail 9 surrounds the first rail 8 and the first rail 8 is routed or guided in the second rail 9. The two rails 8 and 9 are hollow, in particular formed like a channel. In Fig. 1, the extended state of the rail extension device 7 is shown, so that the running rail and in the context of the second rail 9 from the cooking chamber 3 is arranged at least partially protruding.

2, a partial section of the rail extension device 7 is shown. These

Rail extension device 7 is exemplified at a Einhängegitter 10, which may be mounted on a vertical side wall 4a, attached. This is an alternative embodiment for direct attachment and attachment of the

Rail extension device 7 on the vertical side wall 4a. In the illustration shown in transparent in Fig. 2, the two rails 8 and 9 are each formed as a hollow body, or groove-like, and the rails 8 and 9 are guided into each other. As can be seen in the illustration of FIG. 2, the second rail 9 in a cross section perpendicular to its longitudinal axis L, which is also the longitudinal axis of

Rail extension device 7 represents, formed open or circumferentially not closed. The second rail 9 has a C-shape in this cross section. Also, the first rail 8 is formed in this cross-section perpendicular to the longitudinal axis L circumferentially not closed and designed in particular C-shaped.

The rail extension device 7 comprises to the rails 8 and 9, a separate roller body cage 1 1, which is arranged in a space between the rails 8 and 9. The rolling element cage 1 1 is in particular also arranged relative to the two rails 8 and 9 in this intermediate space. The Wälzkörperkäfig 1 1 is part of a Wälzkörpervorrichtung 12 of the rail extension device 7. The Wälzkörperkäfig

1 1 is also formed open in the embodiment in a cross section perpendicular to the longitudinal axis L and in particular C-shaped, as can be seen in Fig. 3 and Fig. 5.

For further explanation, reference is made below to FIG. 3. In this embodiment, the outer and thus the first rail 8 surrounding the second rail 9 is not shown, so that can be looked at the Wälzkörpervorrichtung 12. As can be seen, the roller body cage 1 1 surrounds the first rail 8, so that the first rail 8 extends in a belly 13 of the C-shape.

As can be seen in this embodiment in Fig. 3, the Wälzkörpervorrichtung comprises

12 a first rolling element 14, which is mounted with an axle bearing 15 on the Wälzkörperkäfig 1 1. The axle bearing 15 of the rolling element 14 also includes a rotation axis A, around which a running element 16 of the rolling element 14 can turn. Of the

Wälzkörperkäfig 1 1 comprises a recess 17 which is formed on a top wall 18 of the C-shape and in which the rolling elements 14 is arranged. This recess 17 is bounded by a plurality of boundary walls 19, 20, 21 and 22 (FIG. 4). The running element 16 is contactless and thus also spaced from all of these

Boundary walls 19 to 22 arranged, as shown in the plan view of FIG. 4, which shows a schematically shown portion of the view of Wälzkörpervorrichtung 12, is shown. In this roof wall 18, which represents a viewed in the vertical direction and thus in the y direction upper free leg of the C-shape, are in Embodiment in a row which extends parallel to the longitudinal axis L, a plurality of such first rolling elements 14 are arranged, which are each arranged and stored according to the front first rolling elements 14.

In the exemplary embodiment is also provided that further, second rolling elements 23 are arranged on the Wälzkörperkäfig 1 1. These second rolling elements 23, which in the exemplary embodiment are also several, in particular three, are arranged on a lower leg of the C-shape, this leg representing a bottom wall 24. Again, corresponding bearings are provided as in the first rolling element 14, and also in this bottom wall 24 recesses 17 are formed corresponding to the recess. Again, these rolling elements 23 are arranged without contact to these limiting the recess boundary walls.

In the embodiment, the rolling elements 14 and the rolling elements 23 rollers, but they can also be balls that are mounted with axle bearings. These

Axis bearings with their axes of rotation A are oriented perpendicular to the longitudinal axis L, wherein a displacement direction between the rails 8 and 9 in the direction of

Longitudinal axis L is oriented.

In particular, it can be provided that the axle bearings 15 are arranged in corresponding receptacles on boundary walls of the recess 17, in particular are clipped or engaged. In particular, on the tab-like upstanding and opposite boundary walls 21 and 22, these are

Shooting for the axle bearing 15 is provided. The same is provided in the second rolling elements 23 with their axle bearings 39 (FIG. 3).

In an advantageous embodiment, it is provided that an axle bearing 15 is not fixedly attached to the Wälzkörperkäfig 1 1, but is relatively movable, in particular in a linear direction is movable. In the exemplary embodiment, it is provided that such a relative movement along a path of movement B (FIG. 3) is made possible which is oriented vertically to the longitudinal axis L and vertically to the axis of rotation A. For this purpose, it may be provided that in boundary walls, in particular the

Limiting walls 21 and 22, slots are formed as receptacles for the axle bearing 15. 5, the rail extension device 7 according to FIG. 2 is shown in a perspective sectional view with the sectional plane perpendicular to the longitudinal axis L, wherein a view along the section line VV is shown here. As can be seen here, the first rail 8 is received in a belly 25 of the C-shape of the second rail 9. In an already mentioned gap 26 between the first rail 8 and the second rail 9, the Wälzkörpervorrichtung 12 is slidably disposed. As can be seen in Fig. 5, the second rail 9 on an inside upper side 27, which faces the first rail 8, a first raceway 28, on which the in

Height direction upper first rolling elements 14 are in contact and roll accordingly. It is provided here that this track 28 uneven in this cutting plane

is formed, in particular angled and in the context of a first

Runway surface 28a and an angle thereto arranged second raceway surface 28b, said raceway surfaces 28a and 28b open to each other. It is thus virtually a channel-like career 28 formed.

As can also be seen in FIG. 5, a running surface 16a of the running element 16 of the rolling body 14 is also uneven in this cutting plane and at least partially complementary to the shape of the uneven raceway 28. A particularly straight rolling movement is achieved and the shift in the direction allows so very straight.

In particular, it is also provided that the first rail 8 has on a roof wall 29, which forms an upper free leg of the C-shape, a first raceway, said first raceway 31 is formed on an outside upper side 30. This outside upper side of the roof wall 27 of the second rail 9 faces. Again, it can be seen that the first track 31 of this first rail 8 is uneven and has a first raceway surface 31 a and a second raceway surface 31 b. These too are so open to each other, that in turn a trough-like

or groove-like track 31 is formed. Here, too, it is then provided that the running surface 16a, which is uneven, is complementary to the shape of the raceway 31 and is thus received accordingly, so that here too the straight line

Motion control is supported again. In addition, it is provided that in a lower free leg or a bottom wall 32 of the second rail 9 at an inner side bottom 33, which faces the first rail 8, a second raceway 34 is formed, which in turn is also in the sectional plane perpendicular to the longitudinal axis L is uneven and has a first raceway surface 34a and an opening thereon and angled thereto oriented second raceway surface 34b. Again, it is provided in turn that the rolling element 23 is formed with a running element 35, wherein this running element 35 has an uneven running surface 35a in this cutting plane. This uneven running surface 35a is designed to be complementary to the groove-like shape of the running surface 34. In addition, a further career is formed in a further free leg of the C-shape of the first rail 8. This further lower free leg, which is a bottom wall 36 of the C-shape, has on its outside

Bottom 37, a second track 38, which is also uneven and is designed in particular channel-shaped. Again, two are in particular

Runway surfaces 38a and 38b formed, the angled open to each other and in particular can also open kink-free to each other, as may be the case 31 in the case.

The running surface 35a is again formed correspondingly complementary thereto. It can be seen according to the representation in Fig. 5 that in this embodiment, the upper rolling element 14 with its running member 16, both the raceway 28 and the raceway 31 of the rail 9 and the rail 8 contacted indirectly. Also in the lower rolling element 23 it is provided that the running element 35 contacts the raceway 38 of the first rail 8 as well as the raceway 34 of the second rail 9 directly and simultaneously. The rolling elements 14 and 23 thus contact each and simultaneously a plurality of raceways or respectively a raceway of the first rail 8 and a raceway of the second rail. 9

The Wälzkörpervorrichtung 12, in particular the Wälzkörperkäfig 1 1, 9 is generally relative to the first rail 8 and relative to the second rail 9 in the intermediate space 26 between the notes 8 and 9 in the direction of displacement of the rails 8, 9 slidably disposed. In Fig. 6, a further embodiment of a rail extension device 7 is shown in a schematic plan view, in which case only a plan view of a

Wälzkörperkäfig 40 is shown. The rail extension device 7 also has the rails 8 and 9 here. Also, the construction is the same as in the example explained so far. Also, a plurality of rolling elements 41 are formed, in particular in number and position, as in the previously described embodiment. However, it is not provided here that a stationary axle bearing is designed for a roller body, but rather that a rolling element 41 with clearance is arranged in the recess 17. This means that the rolling element 41 can move as a whole relative to the Wälzkörperkäfig 40 and is rotatably arranged in the recess 17. The game is formed in the direction of the longitudinal axis L. As shown in FIG. 6, provision may be made for boundary walls 42, 43, 44, 45 to be oriented obliquely to the longitudinal axis L in this plan view. As a result, the recess 17 is starting from a

Center region 46 viewed in the direction of the longitudinal axis L tapers. In particular, a diamond shape is formed in this plan view.

It is further provided that the game is limited by the boundary walls 42 to 45. For this purpose, these boundary walls 42 to 45 are oriented so that the rolling elements 41 in the center region 46 in its width (in the plane of the figure perpendicular to the longitudinal axis L) dimensioned here is also arranged with game. The rolling element 41 has contact surfaces 41 a, 41 b, 41 c and 41 d. These are overlap free with a

Running surface 41 e formed, which is designed for contacting and unrolling on a track of a rail 8 and / or 9. The contact surfaces 41 a and 41 b are formed symmetrically to the longitudinal axis L and thus the running surface 41 e is also formed between the contact surfaces 41 a and 41 b. The same applies to the contact surfaces 41 c and 41 d.

In Fig. 6, the state is shown, in which the rolling element has reached an end position of the game in the recess 17, since it is contacted with its contact surfaces 41 a and 41 b on the boundary walls 43 and 44. The running surface 41 e, however, is arranged without contact to the boundary walls 43 and 44 as well as to a particular existing further boundary wall 49 which connects the boundary walls 43 and 44. The same applies to a shift in the opposite direction of the longitudinal axis L and then take place contacting the contact surfaces 41 c and 41 d with the boundary walls 45 and 46, then being here in the other

End position of the game of the rolling element 41 is arranged contactless with its running surface 41 e to a further boundary wall 50.

In addition, it can be seen that a connecting line 47, which extends perpendicular to the longitudinal axis L between the contact points between the contact surfaces 41 a and 41 b and the boundary walls 43 and 44, in a dimensioned in the direction of the longitudinal axis L distance a1 to a central axis 48th of the rolling element 41, which is smaller than a dimensioned in this direction distance a2 between the central axis 48 and the central or central tread 41 e. In particular, the distance a1 is less than or equal to half of the distance a2. Again, therefore, only a minimal lever arm is occurring, since this distance a1 is very small. It is also at this

Embodiment at least a substantial reduction of tilting of the

Wälzkörperkäfigs 40 achieved about an axis perpendicular to the longitudinal axis L.

LIST OF REFERENCE NUMBERS

1 home appliance

2 housings

3 cooking space

4 muffles

4a vertical side wall

4b vertical side wall

6 door

7 rail extension device

8 rail

9 rail

10 suspension grille

1 1 rolling element cage

12 rolling element device

13 belly

14 rolling elements

15 axle storage

16 running element

16a tread

17 recess

18 ceiling wall

19 boundary wall

20 boundary wall

21 boundary wall

22 boundary wall

23 rolling elements

24 floor wall

25 belly

26 space

27 top

28 first career

28a first raceway surface

28b second raceway surface 29 roof wall

30 top

31 first career

31 a first raceway surface

31 b second raceway surface

32 bottom wall

33 inside bottom

34 second career

34a first raceway surface

34b second raceway surface

35 running element

35a tread

36 bottom wall

37 bottom

38 second career

38a raceway surface

38b raceway surface

39 axle storage

40 rolling element cage

41 a to 41 d contact surfaces

41 e tread

42 to 45 boundary walls

46 center area

47 connecting line

48 center axis

49 boundary wall

50 boundary wall

A rotation axis

B movement path

L longitudinal axis

Claims

1 . A rail extension device (7) for a domestic appliance (1), having a first rail (8) and a second rail (9) separate therefrom, which is connected to the first rail (8), the rails (8, 9) being in the direction of their Longitudinal axes (L) relative to each other by means of a Wälzkörpervorrichtung (12) are displaceable in a displacement direction, wherein the Wälzkörpervorrichtung (12) has a Wälzkörperkäfig (1 1), in which at least one rolling body (14, 23) is rotatably mounted, characterized in that the rolling body (14, 23) has an axle bearing (15, 39) which is arranged on the roller body cage (1 1) and the roller body (14, 23) has a running element (16, 35) which is mounted around the axle bearing (15, 39) is arranged in rotation, wherein the running element (16, 35) in a recess (17) of the Wälzkörperkäfigs (1 1) and spaced from the boundary walls (19, 20, 21, 22) of the recess (17) is arranged.

2. rail extension device (7) according to claim 1, characterized in that the Wälzkörperkäfig (1 1) in a cross section perpendicular to a longitudinal axis (L) of the rail extension device (7) is C-shaped.

3. rail extension device (7) according to claim 2, characterized in that the first rail (8) through a belly (13) of the C-shape of the Wälzkörperkäfigs (1 1) extends.

4. rail extension device (7) according to claim 2 or 3, characterized in that in an upper free leg (18) of the C-shape, a first recess (17) is formed, in which a first rolling element (14) with a first

Axis bearing (15) is mounted, and in a lower free leg (24) of the C-shape, a second recess is formed, in which a second rolling body (23) is mounted with a second axle bearing (39).

5. rail extension device (7) according to claim 3 and 4, characterized in that a first running element (16), in particular with an uneven running surface (16a) of the first rolling body (14) on a first raceway (31) formed on the outside upper side (30) of the first rail (8) and a second running element (35), in particular with an uneven running surface (35a), of the second Rolling body (23) on a second raceway (38) formed on the outside bottom (37) of the first rail (8) is present.

Rail extension device (7) according to one of the preceding claims, characterized in that the first rail (8) on an outside upper side (30) has a first raceway (31) which is uneven, in particular channel-shaped and / or the first rail (8) on a outside underside (37) has a second track (38) which is uneven, in particular channel-shaped.

Rail extension device (7) according to one of the preceding claims, characterized in that the second rail (9) on an inside upper side (27) has a first raceway (28) which is uneven, in particular channel-shaped, and / or the second Rail (9) on an inside bottom (33) has a second track (34) which is uneven, in particular channel-shaped.

Rail extension device (7) according to claim 6 and 7, characterized in that a first running element (16), in particular with an uneven running surface (16a) of the first rolling body (14) on the first raceway (31) of the first rail (8) and on the first raceway (28) of the second rail (8) and / or a second race element (35), in particular with an uneven running surface (35a), of the second rolling body (23) on the second raceway (38) of the first rail ( 8) and against the second raceway (34) of the second rail (9).

Rail extension device (7) according to one of the preceding claims, characterized in that the two rails (8, 9) are channel-like and are guided into one another, wherein the roller body cage (1 1) in one

Interspace (26) between the rails (8, 9) is arranged.

10. rail extension device (7) according to any one of the preceding claims, characterized in that the Wälzkörperkäfig (1 1) is arranged relative to the two rails (8, 9) displaceable in an intermediate space (26) between the two rails (8, 9) ,

1 1. Rail extension device (7) according to one of the preceding claims, characterized in that the axle bearing (15, 39) in a direction (B) different from the direction of displacement of the rails (8, 9) to each other relative to the rolling element cage (1 1) is slidably mounted.

12. rail extension device 7 () according to claim 1 1, characterized in that the direction (B) perpendicular to the direction of displacement and perpendicular to a

Rotary axis (A) of an axle bearing (A) is oriented.

13. rail extension device (7) according to one of the preceding claims, characterized in that a plurality, in particular at least three, first rolling elements (14) in a first row parallel to the longitudinal axis (L) of

Rail extension device (7) on the Wälzkörperkäfig (1 1) are arranged and a plurality, in particular three, second rolling elements (23) in a parallel to the first row oriented second row and parallel to the longitudinal axis (L) of

Rail extension device (7) on the Wälzkörperkäfig (1 1) are arranged.

14 rail extension device (7) according to any one of the preceding claims, characterized in that the running element (16, 35) is a roller or a ball.

A rail extension device (7) for a domestic appliance (1), comprising a first rail (8) and a separate second rail (9) connected to the first rail (8), the rails (8, 9) in Direction of a longitudinal axis (L) of the rail extension device (7) relative to each other by means of a

Wälzkörpervorrichtung (12) are displaceable in a displacement direction, wherein the Wälzkörpervorrichtung (12) has a Wälzkörperkäfig (40), in which at least one rolling body (41) is rotatably arranged, characterized in that the Wälzkörperkäfig (40) by a boundary walls (42, 43, 44, 45, 49, 50) has a limited recess (17), in which the rolling body (41) is rotatable and arranged with a in the direction of the longitudinal axis (L) game, wherein in a limited by the game end position of the rolling body (41) in the recess (17) of the Rolling element (41) having a contact surface (41 a, 41 b, 41 c, 41 d) that forms a contact surface (41 e) for contacting a raceway of a rail (8, 9) with a boundary wall (42, 43, 44, 45) is contacted and with the tread (41 e) without contact to the

Boundary walls (42, 43, 44, 45, 49, 50) is arranged.

16. Household appliance (1), in particular for preparing food, with at least one rail extension device (7) according to one of the preceding claims.