GB2415606A - Telescopic rail system for an oven - Google Patents

Abstract

A telescopic rails system 1 for a domestic appliance, such as an oven, comprises an upper rail 2 and a lower rail 4 wherein the upper rail is affixed to an oven wall while the lower rail is movable relative to the upper rail. A mount 8 for a carrier, such as a cooking tray, is attached to the lower rail by means of a connecting pin 16 and substantially covers the two rails. An intermediate rail 3 may be located between the upper and lower rails. The arrangement is intended to reduce the tendency for contamination of the bearings surfaces to ensure that they run smoothly.

Description

TELESCOPIC RAIL SYSTEM FOR A DOMESTIC APPLIANCE

The invention relates to a pull-out system for a domestic appliance, particularly a cooking appliance.

A pull-out system is disclosed in DE 38 15 440 A1, which serves installed together with a pendant in mirror image at side walls of a muffle of an oven - for supporting a carrier for stock to be cooked. The system is composed of three individual pull-out elements: a stationary inner rail, a middle rail displaceable mounted on rollers on the inner rail, and an outer rail slidingly arranged on the middle rail on the same rollers. The rollers are mounted to be floating at one side at the middle rail. Accordingly, the middle rail and the mounting of the rollers there has to be constructed to be particularly solid. The resultant space requirement restricts the usable width in the oven.

In the case of a known telescopic rail installed in a muffle of a baking oven an upper rail equipped with a mount runs in ball-mounted manner on a middle rail, which in turn is displaceable arranged on balls mounted in a stationary lower rail. There is thereby created a vertically extending construction with a small horizontal intrusion into the usable space of the muffle.

An extensive shielding of inner or lower rail is common to both known systems and is intended to prevent contamination of the rails, particularly during baking in an oven, and consequently impaired running characteristics of the rails.

There is therefore a need for a telescopic rail or pull-out system for a domestic appliance, with improved running characteristics and reduced risk of prejudicing the function thereof by contamination.

According to the present invention there is provided a pull-out system for a domestic appliance with at least one upper and one lower pull-out element, of which one pull-out element is mounted to be stationary and the other pull-out element is mounted to be displaceable relative to the stationary pull-out element in longitudinal direction, and with a mount for a cooking stock carrier or other article, where the mount is arranged at a lower pull-out element.

The invention thus departs away from the obvious arrangement of the mount at the upper element or rail, which is easily accessible for a user, and the upper circumferential surface of which advantageously offers itself as a support possibility for a baking tray or the like.

Rather, it follows the principle of arranging the mount at the lower element or rail and thus reversing the path of force within the prior art telescopic rail systems. This has a positive influence on the running characteristics of the system. The element running surfaces, which are pressure-loaded by balls, of the known systems could in operation easily soil, because they are arranged at bowl-shaped deep points at which dirt could get caught and collect, whereby the running surfaces are roughened. Rolling resistance thereby increases and operation of the elements is made difficult. Running surfaces of the elements of a system embodying the invention cannot, thereagainst, soil by themselves. They can be disposed in regions which are open downwardly. No dirt can thereby collect at the running surfaces of the elements, but escapes in the open region.

Since the mount is arranged at the lower element, it cannot be directly arranged on an upper circumferential surface of the element. A special configuration of the lower element or an additional component is therefore required, which offers a conveniently usable support, for example, a food or vessel carrier. According to an advantageous embodiment the mount and the lower element are of two-part construction. With the construction of the mount as a separate component, no special cross-sectional shaping is required for the lower element. In the case of an at least three-part system the same cross-sectional profile can be selected not only for the lower element, but also for, for example, the upper element, whereby the concept of substantially identical parts may be realised. In addition, components of known telescopic rail systems, which are already in mass production, can advantageously be employed without modification of the components.

The mount can be produced from, for example, an aluminium casting with a plated surface or from a comparable material. If the system is intended for a cooking appliance, the material used must withstand temperatures up to 300 C. Production of the mount from stainless steel plate has proved advantageous, particularly because the mount can then be easily welded to the lower element.

Construction of a mount can take place in any desired manner as long as it engages the lower element and a coupling tolerating daily use is provided between the lower element and the cooking stock carrier. According to an advantageous embodiment of the invention the mount, or the lower element with the support, encloses the upper element almost completely with the exception of the end faces thereof. In that case it is merely necessary to leave free a narrow slot in the direction of the length of the element through which there can project, at least in sections, means by which the upper, stationary element can be attached to a side wall of a cooking appliance. A closure of the upper and thus all remaining elements forms, on the one hand, a substantial protection against contamination. On the other hand, it is possible to arrange, as usual, a receiving surface for a carrier on the upper side of the system, which is readily accessible for a user and enables customary use of the cooking appliance. Moreover, this arrangement advantageously makes use of a surface which is present in any case, without unnecessary restriction of the usable interior space of a cooking appliance, as would be the consequence of an arrangement of a receiving surface near, for example, the lower element. In addition, the arrangement produces a central and thus substantially torsion- free introduction of force into the system, whereby premature material wear is counteracted. Finally, it has proved that the construction has sufficient play to provide compensation for imperfections, for example non-parallel or skewed elements.

In normal constructions of telescopic rail systems all elements are of substantially equal length. This on the one hand enables a longest possible pull-out travel of the system and on the other hand is required for secure support of a carrier on the system. However, an advantageous embodiment proposes that the mount is shorter than the carrier. The mount is in that case advantageously so dimensioned that a front part of the carrier does not rest on the mount. In a pulled-out state of the system the carrier can thus be conveniently gripped by a user from both sides so as to be removed from the elements. Since the system leaves free a front region of the carrier it is no longer obstructively in the way of removal or insertion of the carrier.

In an advantageous embodiment the mount comprises means for positional securing of the carrier on the mount. Such means can co-operate with corresponding counter- members at the carrier and can consist of short pins, which project vertically upwards from the mount surface and engage in corresponding holes or eyes in the carrier. Means of that kind are required particularly if the mount is selected to be so short that tipping moments can arise from the unsupported surface of the carrier and hinder positionally secure location of the carrier on the mount. It is therefore advantageous if means able to accept a tipping moment of the carrier are provided at the mount. These means can consist of a hook-like projection which extends in longitudinal direction of the elements and which engages over the carrier and forms a support surface for acceptance of a vertically upwardly directed force. In use, this projection engages over the edge of the carrier remote from a service opening in the appliance and thus absorbs a potential tipping moment from the unsupported region of the carrier. The projection makes possible a mount which is only approximately half as long as - or even shorter than - the depth of the stock carrier. This in turn makes it possible for a user, when removing the carrier, to grip an edge thereof approximately at the level of the centre of gravity and remove it without having to apply restraint against tipping moments and thus with a smaller expenditure of force.

In the case of a conventional cooking appliance, in general two pull-out systems, which are arranged in the same a plane, co-operate for reception of a carrier. According to an advantageous embodiment of the invention the mounts of pull-out systems which are mutually opposite in a cooking appliance are connected together. The connection can consist of a rod or bar and in all cases produces a synchronous setting and synchronous running of the mounts with respect to the stationary elements. Use of the cooking appliance is thereby substantially simplified particularly in the case of insertion of the carrier.

In a further advantageous embodiment of the invention the connecting means can be mounted subsequently and/or without a tool in a holder at the mount. This allows the systems to be mounted individually or in groups initially at respective side walls of the muffle. Interconnection of mutually opposite and co-operating systems, would, even at this point in time, needlessly obstruct their installation. Since the connection of co-operating systems thus takes place advantageously when these are already arranged in the muffle, mounting is not otherwise hampered due to the confined space conditions and poor light conditions in the appliance chamber. It is therefore desirable if use of tools is not required.

In a simple and economic embodiment there can be arranged at each mount Ushaped holders in which, for example, a connecting rod with round crosssection can be hung and retained there by its own weight. The holders in that case have to be of such stiff construction that they can accept moments when only one pull-out element is used and the other is moved together therewith by way of the connecting rod. In a more complicated embodiment the connecting rod has at at least one end a constriction or turning by which it can be suspended in positionally secure manner in the holder and detented in torsionally stiff manner.

In a further advantageous embodiment of the invention the system comprises means against unintended pushing in. The means lock the displaceable element in an extended or a withdrawn setting, only to the extent that the element is released on application of a small use force and can be pushed in again. Such means can, for example, be arranged in the element and in a pulled-out setting detachably fix the position of each individual element relative to another. For this purpose there can be plunge-cut into the elements grooves in which the balls of the element bearing engage in the pulled-out setting and out of which they can be moved again with low force. The grooves can, however, have a negative influence on the running surfaces of the bearing balls. Preferably, therefore, a projection, dog or the like is arranged at the rearward end at the lower element, which on withdrawal of the element slides over a substantially convex run-up element and in that case loads this against the force of a spring. In the completely withdrawn state of the element the spring is relieved again and the projection or dog disposed directly in front thereof. The element can be pushed in again only against the resistance of the spring. It is thereby prevented that the easy-running elements, particularly during fitting of the carrier, are unintentionally and erroneously pushed into the interior of the muffle and the carrier cannot be fitted.

Due to the disadvantageous space and light conditions in the muffle the mounting of the elements should also be designed to be as simple as possible. For this purpose fastenings are suitable which do not require use of tools for the rearward end, which is remote from the service opening of the muffle, of the elements. According to a further advantageous embodiment the stationary element is therefore securable in the appliance in that it can be pushed by a rearward end into a rear side opposite an operating side of the appliance and by a forward end into a region, which is adjacent to the operating side, of a side wall or can be plugged onto or suspended in a projection. The fastening at the rear side can, in a simple case, comprise bores into which the element can be plugged and at which a length compensation can advantageously be provided. In the forward region the element can be suspended in a bush by mechanically positive couple and automatically detented. A fastening is thereby selected which can be applied in simple manner and optionally assuming it is possible and assuming it is required, such as at the service opening of the muffle - also by a tool.

Embodiments of the present invention will now be more particularly described by way of example with reference to the drawings, in which: Fig. 1 is a cross-section of a first telescopic rail or pull-out system embodying the invention; Fig. 2 is a side view of the system in completely extended state; and Fig.3 is a perspective view of a second telescopic rail or pull-out system embodying the invention.

Referring now to the drawings there is shown in Fig. 1 a telescopic rail system as seen from an operating side of a cooking appliance. The system comprises a stationary upper rail or element 2, a middle rail or element 3 and a lower pull-out element 4. The elements 2, 3, 4 are mounted by balls 5, 6 to be displaceable relative to one another. The stationary element 2 has a flange 7 by which the element can be fastened to a side wall (not illustrated) of a muffle of the appliance.

A mount 8 is arranged at the lower element 4 and, in the sectional view, almost completely encloses the upper element 2 and the middle element 3. It merely leaves free a gap 9 through which the fastening of the stationary element 2 to a side wall of a muffle is able to project. The mount 8 forms, at its upper side, a receiving surface 10 or holder on which a cooking stock carrier (not illustrated), such as a baking tray or grill, can be placed. It has humps 11 and 13, the forward visible hump 11 of which carries a hemispherically rounded pin 12. A hook-shaped projection 14, the nose 15 of which projects beyond the receiving surface 10 towards the direction of the observer, is disposed closely behind the rearward, concealed hump 13. Arranged in a lower third and at an end of the mount 8 remote from the observer is a connecting rod 16 which reaches to a mount of an opposite system (not shown) disposed in mirror image at an opposite side wall of the muffle.

Fig. 2 shows the system 1 in its maximum extended setting. The stationary element 2 is disposed completely in the muffle, at the side wall of which it is fastened by a strap 23 arranged at the flange 7 visible in Fig. 1. The mount 8 fastened to the lower system 4, which is not visible in Fig. 2, projects completely out of the muffle and is thus conveniently accessible to and usable by a user. The user can place a cooking stock carrier on the receiving surface 10 in that the user pushes it towards the muffle at a downward inclination to engage a rear edge of the carrier below the nose 15 of the projection 14. On lowering of the carrier into a horizontal position it comes to rest on the humps 11 and 13 and the pin 12 passes through a corresponding eye in the carrier.

The sectional view of Figure 1 clarifies the characteristic construction of the system 1 embodying the invention. The stationary upper element 2, the middle element 3 and the lower element 4 form a construction symmetrical with respect to a centre point M. The upper element 2 and the lower element 3 thus have the same, substantially U-shaped cross-section, whereby the number of different components and the production cost are reduced. The middle element 3 cannot be installed falsely oriented with respect to a horizontal axis, whereby mounting errors are reduced.

Whereas in conventional telescopic rail systems the upper element would be loaded by the carrier, in the system 1 embodying the invention the lower element 5 accepts this load and passes it on to the other elements 2 and 3. A force path reversed with respect to the conventional arrangement thereby results. The main load derived from the weight of the carrier is now transmitted by the balls 5 from the lower element 4 to the middle element 3 and from this to the upper element 2. The balls 6 thereagainst predominantly serve for acceptance of forces deriving from any twisting moments and for guidance of the middle element 3 in the elements 2 and 4.

This has significance for the running characteristics of the system 1, particularly in the case of contamination. By contrast to the conditions in conventional systems, the pressure-loaded running surfaces 17 no longer lie at the horizontal limbs 18 of the U- shaped elements 2 and 4 where dirt can deposit and collect, but lie at the substantially vertical limbs 19, which are difficult for contamination to reach, of the elements 2, 3 and 4.

Obviously contaminations cannot collect there, but drop into the respectively adjoining open region 20 disposed thereunder.

The elements 2, 3 and 4 could, in principle, also be arranged within the mount 8 in mirror image. This does not impair their function in the least, whereby a further possibility of faulty assembly can be excluded. In the system 1 illustrated in Fig. 1, however, there is selected an advantageous orientation of the elements 2, 3 and 4 in which the pressure- loaded running surfaces 17 are each shielded relative to contamination from the muffle by spattering from food being cooked. Disposed between the stationary element 2 and the lower element 4 is a gap 21 which in regions is not covered by the mount 8 and through which contamination, particularly during operation of the cooking appliance, could penetrate. The running surface 17 at the stationary element 2 and that corresponding therewith at the middle element 3 are advantageously arranged thereabove so that, for example, spattering from a food disposed below the system 1 could, at most find a tortuous route through the gap 21 and pass around edges of the lower element 4 and the upper element 2 to the running surfaces 17. This is similarly the case with the pressure- loaded running surface 17 at the lower element 4 and that corresponding therewith at the middle element 3. The gap 22 between the upper element 2 and lower element 4 does indeed lie above the running surface 17, but faces away from the interior space of the muffle and, instead, faces its side wall. The risk of entry of contaminations through the gap 22 is therefore minimised. The running surfaces 17 thus remain largely free and running of the bearing balls 5 is predominantly without obstruction. Long- term ease of running of the elements 2, 3 and 4 relative to one another is ensured with respect to the service life of the system 1.

The mount 8 is fastened to the lower element 4 in order to divert the weight force of the carrier to the lower element 4. The receiving surface 10 generates, by means of the humps 11 and 13, defined bearing points of the carrier on the mount 8. When the carrier is in position, the pin 12 projects through a hole or an eye at an edge of a tray or grill and thus secures the carrier against unintended displacement on the receiving surface 10.

Since the mount 8 has a smaller length than the width of the carrier, whereby it is supported not along the entire course of its edge, but only in a rearward region, tipping of the carrier on the hump 11 in conjunction with a lifting motion of the carrier from the hump 13 could occur. In order to counteract this, the nose 15 at the hook-like projection 14 engages over a region of the rear edge of the inserted carrier and accepts the vertically upwardly directed force, which results from the tipping moment, at the edge of the carrier.

The connecting rod 16 connects the mounts 8 of two opposite systems 1 with one another.

These are thereby always disposed at the same setting relative to the stationary element 2, whereby placement of a carrier on the mounts 8 is facilitated.

Fig. 3 is a perspective view of a system 1 facing a side wall of a muffle. By comparison with the system 1 in Figs. 1 and 2 that illustrated in Fig. 3 has an arrangement of the elements 2, 3 and 4 in mirror image about a vertical axis. Moreover, the mount 8 does not have a hump 13. Finally, the mount 8 does not surround the upper element 2 at its side facing the side wall of the muffle. This difference does not, however, significantly impair the mode of function of the system 1.

By comparison with Figures 1 and 2 a projection in the form of a jog 24 can be seen in Fig. 3 at the lower element 4. In a withdrawn state, which is not illustrated, the jog 24 co- operates with a spring element 25, which is arranged in the vicinity of the strap 23, and thus near a service opening of the muffle, at the front end of the upper element 2. The spring element 25 comprises a leaf spring, at the lower end of which is arranged a run-up surface 26 which is convex with respect to the system 1 and thus arched remote from the observer. When the system 1 is extended, the projection 24 runs against the side of the run-up surface 26 remote from the strap 23 and in further travel urges it, against the force of the spring element 25, in the direction of the side wall of the muffle. In a completely extended state of the system 1 the projection is ultimately disposed in front of the side of the run-up surface 26 facing the strap 23. The spring element 25 is again relaxed. For retraction of the system 1 the same force must again be applied in opposite direction, whereby an unintended pushing-in of the lower element 4 is prevented.

An eye 27, by which the system 1 is pushed onto a pin in the rear wall of the muffle for fastening purposes, is disposed at the upper element 2 at a rearward end of the system 1 facing a rear wall of the muffle.

Claims (24)

1. A telescopic rail system for a domestic appliance, comprising a first rail for mounting in an intended stationary position on such an appliance, a second rail mounted to be displaceable relative to the first rail in longitudinal direction, wherein one of the rails is lower than the other rail when the first rail is mounted on the appliance in the intended position, and support means for supporting an article to be carried by the system, the support means being provided at said lower rail.

2. A system as claimed in claim 1, wherein the support means and said lower element are of two-part construction.

3. A system as claimed in claim 1 or claim 2, wherein the support means and said lower element substantially completely surround said upper element.

4. A system as claimed in any one of the preceding claims, wherein the support means is shorter in the longitudinal direction of the rails than a given dimension in that direction of said article to be supported.

5. A system as claimed in any one of the preceding claims, wherein the support means comprises means for securing the article when supported by the support means.

6. A system as claimed in any one of the preceding claims, comprising connecting means for connecting the support means of the system with the support means of another such system mounted on the appliance in a position opposite to that of the first-mentioned system.

7. A system as claimed in claim 6, wherein the connecting means is attachable to the system subsequent to mounting thereof on the appliance.

8. A system as claimed in any one of the preceding claims, comprising means to resist retraction of the rails of the system from a telescopically extended setting.

9. A system as claimed in any one of the preceding claims, wherein the first rail can be mounted on the appliance by insertion at one end into a rear wall of the appliance and at the other end into a side wall region adjacent to an operating side of the appliance.

10. A system as claimed in any one of claims 1 to 8, wherein the first rail can be mounted on the appliance by plugging into or suspension at a projection or projections.

11. A system as claimed in any one of the preceding claims, wherein the support means is a cast component.

12. A system as claimed in claim 10, wherein the support means is a sheet metal component.

13. A system as claimed in claim 1, wherein the support means has a wall portion bridging a junction of the rails and the first rail is adapted to be mounted on the appliance at a wall of a chamber of the appliance with the wall portion of the support means remote from that chamber wall.

14. A system as claimed in any one of the preceding claims, wherein the support means extends around said upper rail without contact therewith.

15. A system as claimed in claim 1, wherein the support means has a slot permitting passage of fastening means for fastening the first rail to a wall of a chamber of the appliance.

16. A system as claimed in claim 1, wherein the support means has a substantially right-angled profile in cross-section of the system.

17. A system as claimed in any one of the preceding claims, wherein the support means in cross-section bounds a substantially closed space in which at least one of the rails is disposed.

18. A system as claimed in any one of the preceding claims, wherein the support means comprises a holder for the article to be supported.

19. A system as claimed in claim 18, wherein the holder is disposed at the top of the system when the first rail is mounted in the intended position.

20. An appliance equipped with a system as claimed in any one of the preceding claims.

21. An appliance as claimed in claim 1, wherein the appliance is a cooking appliance and the system is arranged in a cooking chamber of the appliance.

22. An appliance as claimed in claim 21, comprising two such systems respectively arranged on two opposite side walls of the chamber.

23. An appliance as claimed in claim 22, comprising a tray supported by the support means of the two systems.

24. An appliance as claimed in claim 23, wherein the tray is detachably connectible with the support means.