Pull-out system for household appliance

The invention relates to a pull-out system for a household appliance, particularly cooking appliance, the at least one stationary support rail and a movable slide rail for mounting having a food support, of which at least one first rail with a coated first layer comprising a lubricant.

From EP 0994309 A2 a generic extension device is known, which partly having a cooking chamber removable rails. These are in fixed guides slidably guided. The rails and / or the guides are at least on their slide surfaces provided with a low friction material.

DE 102 11 470 A1, a generic extension system is known that a fixed inner rail, a movable intermediate rail and a movable outer rail having. The rails are equipped with an easy-to-clean based on PTFE Layer. Depending on the accessibility of rails and components for food to be cooked and / or the users are provided different coating qualities. Let it be to component regions that are facing down, with a view to cleanability equip and / or abrasion resistance lower coating qualities, as upwards looking component areas that Gargutspritzern direct exposure.

From DE 199 49 239 A1 is a pull-out device, in particular telescopic pull-out device, known in the rails by means of ball bearings or roller bearings on stationary Guided tours are conducted. The balls are made of ball bearings or rollers of the roller bearing at least on its surface made of a self-lubricating material.

DE 38 15 440 a telescopic insertion device is known as a telescopic extension with a stationary inner rail, a middle rail and a rollable is formed rollable outer rail for product support. At the middle rail are each two rollers via bolts mounted. In the pin grooves are formed, which the Receiving high-temperature resistant grease or used lubricating paste.

The object of the invention is to provide a pull-out system for a household appliance, having permanently good running or gliding.

The object of the invention is a household appliance having the features of claim 1 dissolved. According to the patent claim 1 is known from the rails at least one first track with a first layer coated comprising a lubricant. On the other hand at least one second rail is coated with a second layer or uncoated. According to the invention it has been recognized that there is sufficient lubrication the entire extract system is sufficient only one of the rails with a Lubricant layer to provide. From the lubricant layer abraded lubricant particles can in the pull-out system according to the invention also running or sliding surfaces achieve, not with a lubricant layer in contact. This is sufficient to task according maintain a smooth running of the extract system.

Next arising after the claim 1 for the rails different surface characteristics. This allows the running or sliding of the pull system be substantially increased. The running or sliding behavior improves in particular if the rails coated with layers of different surface hardness are. In regard to a cheap manufacturing it is preferred if at least one is the rails uncoated, ie, has a metallic surface.

It is particularly preferred if the coated with the lubricant layer first Rail is a movable rail. By means of the movable rail is a good distribution the lubricant reaches the pull-out system. consisting With a pull-out system from a stationary support rail and a movable slide rail, it is sufficient therefore from when the movable pull rod coated with the lubricant layer is. The stationary retaining rail can, however, be coated with another layer his or uncoated.

In the event that between the movable pull-out rail and the fixed holding rail an intermediate rail is mounted, it is sufficient in the present invention, when only one of the three tracks is coated with the lubricant layer. particular preference it is there when the intermediate rail is coated with the lubricant layer. In this case, the intermediate rail, both the pull-out rail and the support rail provide roughly the same amount of lubricant. In this case, production engineering vorteilig A coating of the support rail and / or the pull-out rail be waived. Alternatively, the outer pull-out rail and / or the stationary inner Retaining rail be provided with another, such as corrosion-resistant layer.

It is particularly preferable if the lubricant is an inorganic solid lubricant is. Such a lubricant is in contrast to many other lubricants, such as as liquid lubricants from oil or fat, even at high temperatures physiologically harmless.

It is advantageous if the lubricant is chemically resistant, particularly alkali resistant is to enable cleaning in a dishwasher. In this case can extract system chemically aggressive media, for example, bases in a dishwasher, are exposed.

Inorganic solid lubricants can be particularly easily from a layer structure to solve. A distribution of the inorganic solid lubricant components that do not use the Solid lubricant coated is therefore particularly simple possible. squeaks or binding of the extract system are therefore reliably prevented.

According to the invention, it may be advantageous if the lubricant high temperature resistant is. To this end, all lubricants are possible, up to the maximum cooking operation temperatures of up to 300 ° C, and optionally up to 500 ° to 60 0 ° C in the pyrolysis are resistant. It is particularly preferred in this case if the solid lubricant graphite is used. Graphite is used even at very high temperatures and chemically resistant and inexpensive. Further, as the solid lubricant molybdenum disulfide be used. In this case, it may, however, at very high temperatures due to the generation of S₂ be problematic. If the production costs only are of secondary importance, is as solid lubricant also boron nitride conceivable that in all temperature ranges is resistant and physiologically harmless. The same also applies to tungsten.

It is advantageous if the lubricant layer comprises a binder, which the holds lubricant on the rail. The binder causes an improved connection the lubricant with the rail surface. One such compound is in contrast not added when the lubricant merely in a roughened surface rail Maintenance found. Particularly advantageous in view of a lubricant layer with uniform thickness and uniform surface properties, it is, when the binder is a lacquer. This can for example be sprayed onto the rail be, resulting in a uniform layer thickness. Subsequently, the on baked rail varnish applied together with the lubricant in the rail will. Vorteilig the lubricant in the coating is suspended. By the achieved can burn permanently reliable lubrication properties of the rail , even if the telescopic pull chemically aggressive media or high is exposed to temperatures.

The abrasion resistance of the coating bar or the coating quality requirements accordingly adjust, are also combinations of the above Solid lubricants made of graphite, molybdenum disulfide (MoS₂), Boron nitride or tungsten conceivable.

Compared to a plain bearing, a roller bearing with a system in the abstract improved pullout behavior can be achieved. In contrast to a sliding bearing no frictional force is generated between the moving parts, but the roll movable components on rolling elements against each other. Consequently, when a pull-out system required with plain bearing substantially less lubricant. It can therefore a lubricant layer are used with high lower requirements.

According to the invention, the lubrication of the extract system via only on the intermediate rail provided lubricant layer can be achieved. Other components in the Excerpt system about rails, rolling elements or Wälzkörperkäfige therefore have no Lubricating function assume. The rolling elements and / or their Wälzkörperkäfige can are therefore specifically designed as limit stops. Faults or loads could, for example, on carbon-based Wälzkörperkäfige (so-called. PEEK cages) not withstanding.

Manufacturing technology, it is preferable if the intermediate rail fully with the Lubricant is coated. Compared to an only partial coating of the intermediate rail can thus be considerably simplified, the coating operation.

Plays the manufacturing costs for applying the lubricant layer on the rail only a subordinate role, so it is conceivable several layers having different lubricant apply properties. In this case, a bottom layer location comprise a large proportion of binders and correspondingly little solid lubricant. Characterized an abrasion-resistant retention of the lubricant on the rail is secured. A top layer, however, can at little binder and for a high proportion having solid lubricant. This is the lubricating property of the intermediate rail elevated.

Moreover, containing the lubricant layer may further fillers, such contain ceramic to adjust its film quality or abrasion resistance.

According to a further embodiment, the pull-out system can be removed in the cooking appliance to be supported. In this case, on the one hand a simple cleaning of the Excerpt system outside of the cooking device achieved. On the other hand, for example, in a pyrolytic cooking appliance in the extension system are taken out to make it not to expose the high temperatures needed for pyrolysis.

Preferably, the pull-out system may be designed such that the lubricant layer with the coated rail is protected from contamination. For example the holding rail and / or the pull-out rail bound a cavity in which coated with the lubricant layer intermediate rail is arranged. In this Case, the intermediate rail at least in the cooking operation in the holding rail / pull-out rail formed cavity inserted. Contamination of the intermediate rail by cooking liquid or vapors is substantially reduced. This makes sense in that the lubricant layer, an inorganic solid lubricant having. One such lubricant layer has excellent lubricating properties on, however, is difficult to clean. This is due to the physical properties of founded by inorganic solid lubricants. The poor cleanability plays but only a minor role, if that lubricant layer having Rail is largely protected against contamination.

Listed below are two embodiments of the invention with reference to the attached figures described. Show it:<dl tsize="7"><dt>figure 1</dt><dd>according to the first embodiment of a pull-out system in a cooking appliance;</dd><dt>figure 2</dt><dd>in a sectional view the extension system of the cooking device;</dd><dt>figure 3</dt><dd>a ball cage of the extract system; and</dd><dt>figure 4</dt><dd>according to a second embodiment, a pull-out system in a cooking appliance.</dd></dl>

In the figure 1 according to the first embodiment of a cooking appliance with a cooking appliance muffle 1, the delimiting a cooking chamber. The cooking device has a hinged door 3 for closing a frontal muffle opening 5. In the figure, 1 is the hinged door 3 shown in an open state. On opposite side walls 9 of the Cooking device muffle 1 are corresponding lateral guide rods 11 and a pull-out system, consisting of two opposed telescopic extension 13, supported. The telescopic extension 13 are in a top four horizontal Garraumebenen removably mounted. In the underlying three Garraumebenen are respectively the corresponding guide rods 11 removably mounted. On the two corresponding lowermost guide rods 11 is supported a baking sheet 13 from which partly is pushed out of the cooking appliance muffle first The guide rods 11 are muffle front each inserted in a bearing bush 15th This is in a mounting opening of Muffle side wall 9 is mounted. The telescopic extension 13 are formed with a holding plate 14, which is mounted in each case in an annular groove 16 of the bearing bush 15th In the area a muffle rear wall 17, the guide rods 11 and the telescopic extension 13 each mounted in a mounting hole 19th Both the guide rods 11 and the Telescopic shelves 13 are no tools to solve by a user from the muffle. 1

In the present case, the pull-out mechanism 13 is constructed as a telescopic extension. The telescopic extension 13 is in accordance with the figure 2 in a viewing direction I shown in the figure 1 in cross-section shown. The telescopic extension 13 has a lower support rail 23, the is held on the holding plate 14 fixed on the muffle side wall. 9

Both the holding plate 14 and the bushing 15 are in Figure 2 with dashed Lines shown. In addition to the stationary support rail 23 consists of telescopic extension 13 from an intermediate movable rail 25 and a likewise movable extension rail 27. The intermediate rail 25 is about 29 balls between the pull-out rail 27 and the stationary support rail 23 mounted.

The configuration of the rails 23, 25, 27 is not limited to the present embodiment limited. Thus, the retaining rail 23 also formed as a round rod 11 be. On the retaining rail 23, the pull-out rail can slide or other rolling elements be guided stored. The design of the pull rod 27 is not in the present embodiment is limited. Rather, the pull rod 27 can be designed as a slide, a runner or other pull-out element. can also on the arrangement between the pull-out element 27 and the retaining rail 23 the intermediate rail 25 are omitted.

The holding rail 23 and the pull rod 27 are in accordance with Figure 2 of another identically formed U-profile parts of an uncoated steel. The two rails 23, 27 are arranged facing each other with their open sides. They define a substantially closed cavity 31 in which the intermediate rail 25 is disposed. That is, at least in the inserted state of the Telescopic extension 13, the intermediate rail 25 almost completely from the pull-out rail 27 and the retaining rail 23 is enclosed. Fat splashes, dirt or the like therefore be kept away from the balls 29 and of the intermediate rail 25th

To a smooth pulling and pushing together of the pull system to allow the intermediate rail 25 is coated with a lubricant layer 33rd The Lubricant layer 33 is shown in Figure 2 in exaggerated thickness. The Layer thickness is realistically in a range between 10 and 20 microns. In contrast to the intermediate rail 33, both the balls 29 and the retaining rail 23 and the pull rod 27 is not coated with the lubricant layer 33 but uncoated. This run the balls 29 on the one hand on the lubricant layer 33 of Between rail 25 and on the other hand to the uncoated bearing surfaces of the holding rail 23 and the pull rod assembly 27th

The surface properties of the metal surface of the balls 29, the retaining rail 23 and the pull-out rail 27 on the one hand and the lubricant layer 33 on the other hand are different. Because of this different surface properties obtained a particularly good rolling of the balls 29 and thus good runnability the extract system.

Alternatively, the retaining rail 23 and / or the pull-out rail 27 with a second be coated layer as in Figure 2 by the reference numeral 34 with dashed Line is indicated. The two different layers 33 and 34 have different Surface properties. In particular, in a different Surface hardness improve the rolling motion of the ball 29th The second layer 34 may be formed for example as a corrosion resistant layer.

In the present case, the lubricant layer 33 particles of an inorganic solid lubricant, such as graphite. To prepare the lubricant layer 33 is first suspended a powder of the inorganic solid lubricant in a coating solution and so then the intermediate rail 25 coated. In a further step the coating solution is baked in the intermediate rail 25th This results an extremely high mechanical abrasion resistance of the coating 33 and a good chemical resistance to aggressive media, such as detergents. In addition to this cost-painting are also other methods, such as a PVD (Physical Vapour Deposition) or CVD coating (Chemical Vapour Deposition) for the preparation of the lubricant layer 33 is conceivable.

The lubricant layer 33 of the intermediate rail 25 is sufficient to also between the Balls 29 and the pull rod 27 and the holding rail 23 sufficient lubricant bring. The shown in the Figure 2 U-shaped rails 23, 27 are thereby particularly well, the intermediate rail 33 to protect against contamination. at the rails shown in the figure 2, it is sufficient, the lubricant layer 33 only with respect to adapt its lubricating properties. Of secondary importance in this Case, the cleaning ability of the lubricant layer 33. The protection against contamination the lubricant layer 33 is namely of the U-shaped retaining rail 23 or the pull rod assembly 27 taken. These act, at least in the inserted state as cover elements relative to the intermediate rail 25. A contamination of the Intermediate rail 25 is therefore greatly reduced.

Only such a protection of the intermediate rail 25 against contamination therefore allows meaningful way to coat the intermediate rail 25 with the inorganic solid lubricant layer 33. Such a layer that is - compared to about a PTFE-based coating - very difficult to clean.

According to Figure 2, the balls 29 are arranged in two opposite ball cages 37th The balls 29 are rotatably supported in the ball cages 37th One of the ball cages 37 shown in FIG. 3 The ball cage 37 consists of a thin steel sheet, at an angle part with three profile trapezoid disposed sides 39 formed is. In each of the sides 39 recesses 41 are cut out. The recesses 41 are on each side 39 arranged in two successive rows. The two rows are spaced apart across a center portion 43 of the ball cage 37th Each recess 41 is partially defined by an angled edge embossing 45, the ball 29 in the Recess 41 keeps.

The ball cages shown in Figures 2 and 3, 37 are additionally provided with the lubricant layer 33 coated. In the figure, 2 is the force applied to the ball cage 37 Lubricant layer 33 indicated by a dashed line. In the Figure 3 which is on the Ball cage 37 applied lubricant layer 33 indicated in hatching. Thereby due to the rotation of the balls 29 at the angled embossing edge 45 a minor Lubricant abrasion are generated. The abrasion is by adjusting the telescopic extension 13 along the running surfaces of the rails 25, 23, 27 distributed. Thus, the pullout behavior of the extract system is permanently improved. Further are squeaking or sluggishness in the operation of the telescopic extension effectively reduced. The application of the lubricant layer 33 on the ball cage 37 takes place as the application of the lubricant layer 33 to the respective Rail.

The ball cages 37 are arranged between the rails 23, 25, 27 can move freely in the longitudinal direction. The end faces 47 of each ball cage 37 are used in the telescopic extension shown in the figure 2 13 as stops which limit longitudinal movement of the rails 23, 25, 27th The telescopic extension 13 can be pulled apart so long, therefore, until the End faces 47 of the ball cage 37 into engagement with corresponding, not shown rail stops come.

4 shows a cooking appliance according to the second embodiment, the the corresponding cooking appliance of the first embodiment. The only difference from the first Embodiment are that the slide rails 13 of the extract system from the stationary support rail 23 and the pull rod assembly directly mounted thereon 25 there. On the intermediate rail 25 is omitted. Here, the pull-out rail 25 mounted as in the first embodiment via balls 29 in the ball cages 37 supported.

In the figure 4, the movable slide rail 27 with the lubricant layer 33 coated. By adjusting the slide rail 27 is the lubricant distributed in sufficient quantity in the extract system. In contrast, the stationary support rail 23 uncoated. The balls 29 therefore roll between the rolling surfaces with different Surface properties, resulting in a particularly good rolling of Balls 29 and thus provides good running properties of the extract system.