Abstract:
A telescopic rail with at least two rail elements displaceable relative to each other in a longitudinal direction, which comprise at least one outer rail ( 1 ), one inner rail ( 2 ) and optionally one or more middle rails, in which the rail elements have supporting surfaces, sliding surfaces or both, and in which in each case between two rail elements arranged displaceably against each other, at least one slide element ( 3 ) is provided. In order to provide a telescopic rail in particular for the car industry, which can support high loads with comparatively compact dimensions, according to the invention the slide element ( 3 ) has slides which extend between the supporting surfaces and sliding surfaces of two rail elements displaceable against each other and are in contact with the sliding and supporting surfaces.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a telescopic rail with at least one outer rail and one inner rail which have supporting surfaces or sliding surfaces and are displaceable relative to each other sliding in a longitudinal direction, a slide element being provided between outer rail and inner rail.  
         [0002]     From the state of the art, telescopic rails are known on which the most diverse objects can be fitted in linearly displaceable manner. Such telescopic rails are used for example in furniture construction, household appliances, e.g. pull-out racks for ovens or also in car construction.  
         [0003]     Conventional telescopic rails have outer and inner rails which are displaceable against each other. The displacement of the two rails relative to each other is ensured by incorporating ball bearings, i.e. mostly balls guided in ball cages. These considerably reduce the friction between the rails.  
         [0004]     New uses, but also increased requirements for operating comfort, make it necessary to develop telescopic rails in which not only good displaceability of the two rails relative to each other is at the fore, but in addition also the possibility of braking the running of the rails, the ability to displace the rails against each other in discrete steps or with locking positions along the pull-out rack. In the car industry in particular, increasingly higher loads must moreover be carried by the telescopic rails. An example of this is e.g. pull-out racks for loading surfaces.  
         [0005]     Standard rails with ball bearings cannot fulfil the abovementioned requirements, as their carrying capacity can be increased only by increasing the dimensions of the rails and the balls used. The ball cages fitted into the rails, with the balls contained therein, take up a large part of the intermediate space between outer and inner rail, with the result that only a small space is available for fitting additional devices, e.g. for braking the displacement between the two rails.  
         [0006]     For some time, telescopic rails have also been used for pull-out racks in ovens. The increasingly high temperatures in the ovens, e.g. in new pyrolysis ovens, make lubrication of the ball bearings increasingly difficult. Greases or oils must be used which not only withstand the high temperatures, but are also suitable for food.  
         [0007]     In addition, the cleaning of the rails with ball bearings is difficult and expensive, as dirt collects especially between the balls and the balls cannot be removed by the user.  
         [0008]     The assembly of standard telescopic rails is moreover expensive and cost-intensive, as the rails, balls and ball cages have to be put together to produce an operational element after production of the individual parts. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1A  shows a cross-section through a version of the telescopic rail according to the invention.  
         [0010]      FIG. 1B  is a cross-section through the individual elements of the telescopic rail according to the invention from  FIG. 1A .  
         [0011]      FIG. 2  is a three-dimensional view of a telescopic rail of  FIG. 1  according to the invention as seen obliquely from above.  
         [0012]      FIG. 3A  is a broken-off side view of a slide element according to the invention with offset locking elements.  
         [0013]      FIG. 3B  is a broken-off three-dimensional view of the slide element of  FIG. 3A  seen obliquely from above.  
         [0014]      FIG. 4A  is a broken-off side view of an alternative version of the slide element according to the invention with opposite locking elements.  
         [0015]      FIG. 4B  is a broken-off three-dimensional view of the slide element of  FIG. 4A  seen obliquely from above.  
         [0016]      FIG. 5A  is a broken-off side view of a slide element according to the invention with eccentric brake.  
         [0017]      FIG. 5B  is a broken-off three-dimensional view of the slide element with eccentric brake of  FIG. 5A  seen obliquely from above.  
         [0018]      FIG. 6A  is a broken-off side view of an alternative version of the slide element with eccentric brake.  
         [0019]      FIG. 6B  is a broken-off three-dimensional view of the slide element with eccentric brake of  FIG. 6A  seen obliquely from above.  
         [0020]      FIG. 7A  is a broken-off side view of the slide element according to the invention with a sliding brake.  
         [0021]      FIG. 7B  is a broken-off three-dimensional view of the sliding brake of  FIG. 7A  seen obliquely from above.  
         [0022]      FIG. 7C  is a three-dimensional view of the slide seen obliquely from above,  
         [0023]      FIG. 8A  is a broken-off side view of the slide element according to the invention with end stop.  
         [0024]      FIG. 8B  is a broken-off three-dimensional view of the slide element according to the invention with end stop of  FIG. 8A  seen obliquely from above.  
         [0025]      FIG. 9  is a side view of an alternative version of a slide element according to the invention with eccentric self-locking brake and two end stops.  
         [0026]      FIG. 10  is a side view of an alternative version of a slide element according to the invention showing an intermediate rail  35 .  
         [0027]      FIG. 11  is a side view of a further alternative embodiment showing an intermediate rail  35 . 
     
    
     BRIEF SUMMARY OF THE INVENTION  
       [0028]     The object of the present invention, vis-à-vis the present state of the art, is therefore to make available a telescopic rail which solves the abovementioned problems.  
         [0029]     This object is achieved by a telescopic rail with at least two rail elements displaceable against each other in longitudinal direction which comprise at least one outer rail, one inner rail and optionally one or more middle rails, in which the rail elements have supporting surfaces or sliding surfaces and in which in each case at least one slide element is provided between two rail elements arranged displaceably against each other, and the slide element has slide regions or slides which extend between the supporting and sliding surfaces of two rail elements displaceable against each other and are in contact with the latter.  
         [0030]     The slide element, the slides of which extend between the supporting or sliding surfaces of the rail elements, carries the load secured to the telescopic rail flat via a large bearing surface. So in comparison to standard telescopic rails with ball bearings of the same structural size, higher carrying capacities can be achieved. As the slides of the slide elements between the supporting and sliding surfaces of the slide elements are small in comparison to ball bearings with corresponding load capacities, there is in the intermediate space between outer and inner rail sufficient space available for further operational elements to be fitted here. If a suitable plastic, preferably polyoxymethylene/polyacetal (POM) or polyamide is used for producing the slide elements, additional lubrication of the sliding surfaces can be avoided.  
         [0031]     More particularly, the invention includes A telescopic rail having at least two rail elements displaceable against each other in a longitudinal direction, at least one of the rail elements having a supporting surface and at least another of said rail elements having a sliding surface. The supporting surface and the slide surface being proximate each other and displaceable relative to each other and at least one slide element is provided between the supporting surface and the slide surface. The slide element has slides that are located between and contact the supporting surface and sliding surface.  
         [0032]     The telescopic rail of the invention may, for example, have an outer rail, an inner rail and at least one middle rail where the outer rail is provided with a support surface for mating with a slide surface of a middle rail and the inner rail is provided with a slide surface for mating with a support surface on a middle rail and a plurality of slides are provided between the support and slide surfaces.  
         [0033]     Sections of the rail elements forming the supporting or sliding surfaces may have an essentially U-shaped cross-section and the slides of the slide element desirably have a cross-section preferably adapted to the U-shaped cross-section of the sections forming the supporting or sliding surfaces. The slides of the slide element are desirably connected with each other with a connection section and the supporting or sliding surfaces of the rail elements grip the slides to the extent that the rail elements are held together and prevented from separating.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0034]     Preferably, a version of the invention is used in which the sections of the rail elements forming the supporting or sliding surfaces have an essentially U-shaped cross-section, the slides of the slide elements have a cross-section preferably adapted to the U-shaped cross-section of the sections forming the supporting or sliding surfaces, the slides ( 7 ) of the slide elements ( 3 ) with a connection section ( 18 ) are connected with each other and the supporting or sliding surfaces of the rail elements grip the slides to the extent that the rail elements are held together and prevented from separating. This construction allows simple assembly of the rail elements or slide elements, the latter being held together without further devices. In addition the U-shaped cross-section of the slides allows very good guiding of the rail elements.  
         [0035]     Customary profiles of telescopic rails (individual rail elements) have an essentially C-shaped cross-section with supporting or sliding surfaces lying opposite each other and facing each other as curved sections of an intermediate connection section or “back wall” of the C-shaped profile. In the slide element according to the invention the slides are expediently connected with each other via a connection section or back. Particularly preferably, the profile of the slide element is adapted to the internal profile of the rails, to which the slide element is to be secured or in contact, with little or no clearance.  
         [0036]     A version of the invention is particularly preferable in which the slide element between two rail elements displaceable opposite each other is secured to one of the rail elements against displacement in longitudinal direction relative to said rail element. Thus additional operational features of the telescopic rails can be produced on the slide element secured to one of the rail elements.  
         [0037]     It is expedient if the slide element is secured by clamping to one of the two rail elements. If the slide element is produced from a flexible or pliable material, such as e.g. plastic, the slide element can be “clipped” between the slides into the U-shaped rails by pressing the slides together whilst slightly bending the connection section. This allows simple assembly. It is particularly advantageous if the clamping forces are calculated such that the individual elements can be easily separated from each other. Thus the sliding rails can be cleaned separately from the rail elements, e.g. in a dishwasher.  
         [0038]     In a further preferred version of the invention, the telescopic rail has, between two rail elements displaceable against each other, several slide elements arranged side by side with or without some distance from each other. This makes it possible, to be able to produce telescopic rails of differing total lengths with a single length of slide elements. Purely sliding elements can e.g. also be combined with such elements which have additional operating features, as described below.  
         [0039]     A version of the invention is advantageous in which between the outer rail and the inner rail, a middle rail is additionally provided, a slide element being provided between outer rail and middle rail and between middle rail and inner rail in each case. Thus a full extension with the slide elements according to the invention can be achieved, it being possible to pull out the telescopic rail to double the length of its rail elements.  
         [0040]     It can be expedient if both the slide element and also the outer and inner rail are displaceable sliding relative to each other in longitudinal direction in each case. Thus a full extension is formed in which the middle rail is formed by the slide element.  
         [0041]     A version of the invention is particularly preferred in which the slide element is produced from plastic, preferably polyoxymethylene/polyacetal (POM) or polyamide. If plastics are used for the slide element between the rail elements, additional lubrication can be avoided. This is particularly advantageous if the telescopic rail is to be used in an oven at high temperatures.  
         [0042]     A version of the invention is preferred in which the slide element has at least one locking element and one rail element has at least one device for locking into the locking element. This makes it possible to brake the linear displacement between two rail elements at specific points, and to detachably fix the two elements against displacement at these points. This is desirable, e.g. if the middle armrest in a vehicle is to be arranged adjustably in steps.  
         [0043]     It is particularly expedient if the locking element in the direction of the displacement of the rail elements has lead-in and lead-off inclines, and a recess in between, and the device has a locking pin for locking into the locking element on the rail element. Such a locking element can be integrated directly into the slide element and be cast together with the latter.  
         [0044]     It is advantageous if the slide element has several locking elements offset relative to one another, with the result that a displacement of the two rails in discrete steps between adjacent locking positions is possible.  
         [0045]     If it is necessary to arrange particularly firm locking positions at specific points on the displacement path, it can be expedient to arrange two overlapping locking elements on the slide element, with the result that the locking pins can be simultaneously locked into both locking elements. Thus increased holding forces can be achieved.  
         [0046]     Preferably the telescopic rail according to the invention can have one or more devices for braking the sliding longitudinal displacement of two rail elements relative to each other. Thus a telescopic rail can be produced the extension of which can be fixed in any position.  
         [0047]     In a preferred version the device for braking the sliding longitudinal displacement between two rail elements has one or more brake shoes, which are elastically mobile and which can be pushed apart by an eccentric, with the result that they come into friction contact with one of the rails. This construction makes it possible to actively inhibit the relative displacement of the two rails, e.g. by rotating a knob secured to an eccentric or pushing a lever. The construction is in addition simple to produce, as, apart from the eccentric, all the parts can be cast together with the slide element e.g. in an injection-moulding process.  
         [0048]     Alternatively, the device for braking can be an eccentric self-locking brake. This allows smooth braking throughout the available movement path.  
         [0049]     It is expedient if the eccentric brake has at least one rotatably supported eccentric pre-tensioned with a spring, which is pushed against the inner surface of the inner rail, the eccentric being formed such that it is movably driven by the inner rail or carried along in the locking direction. The specific design of the eccentric allows increased braking when it is attempted to move the rails against one another.  
         [0050]     A version of the invention is advantageous in which the eccentric can be rotated by a rotatably supported cam against the spring tension out of the region of the friction engagement with the inner rail. The braking action of the eccentric brake can thus be smoothly reduced or increased by the user of the telescopic rail in order to displace the rail elements against each other.  
         [0051]     It is expedient if the telescopic rail has a device for braking the displacement between inner rail  2  and outer rail  1 , which consists of a slider which is spread by a fixed pin if it is displaced by the inner or outer rail, with the result that at least one of its outer surfaces comes into frictional engagement with one of the rail elements as a brake shoe and thus checks the relative displacement between the rails.  
         [0052]     A version of the invention is preferred in which the slide element has devices for braking the sliding longitudinal displacement of the rail elements relative to each other in contact with each other in each case on reaching maximum extension, thus preventing a slide element, when fully extended, being pulled out of its guide and dropped.  
         [0053]     A version of the invention is advantageous in which the slide element has at least one end stop for limiting the displacement of two rail elements, in order to prevent one of the rail elements from falling out of its guide.  
         [0054]     It is expedient if the end stop has at least one lead-in incline, with a recess behind it for locking a rail element in the extended position. Thus, not only is an end stop formed, but in addition the rail element is detachably secured against displacement when fully extended.  
         [0055]     The slide element according to the invention, as described above, is also expedient for other forms of rail or pull-out rack.  
         [0056]     Further advantages, features and possible uses of the present invention will be clear from the following description of a preferred version and the accompanying figures.  
         [0057]      FIGS. 1A and 1B  show a side section through the telescopic rail according to the invention, clearly showing the construction from the three elements, the outer rail  1 , the slide element  3  and the inner rail  2 . In the version represented, the outer rail  1  forms the stationary rail which e.g. is secured onto the body of a cupboard. In just the same way, the inner rail  2  can also be the stationary rail. The slide element  3  has two regions which extend as slide  7  between the supporting  5  or sliding surfaces  6  of the inner  1  and outer rail  2 . The two slides  7  are connected with each other with the connection section or back  18 . The slide element  3  is simply inserted into the outer rail  1  by pushing together the slide  7  while slightly bending the back wall  18 , and is firmly clamped with the slides  7 , which lie between the supporting surfaces  5  and sliding surfaces  6  of the outer or inner rails, in the outer rail  1 . The projection  15  in the back wall  18  of the slide element  3  in addition prevents slipping of the slide element vis-à-vis the outer rail, by engaging in a hole in the outer rail. The inner rail  2  is now clamped into the slide element  3  such that its sliding surfaces are supported on the slides  7  of the slide element  3 . The locking pin  4  on the inner rail, which can be brought into engagement with locking elements  10  on the slide element  3 , is also clearly shown. This is also clearly shown in  FIG. 3A . Here three locking elements  10  offset vis-à-vis one another are clearly shown. These are cast directly on the slide element  3 . In the region of the locking elements  10  the slide element  3  is formed such that behind the locking elements the back wall  18  is provided with notches  17  or recesses such that the locking elements  10  are elastically mobile. The locking elements extend in longitudinal direction parallel to the path of movement of the inner rail. This is also clearly shown in  FIGS. 3A  and B. The locking elements  10  have lead-in and lead-off inclines  19 , and a recess  14  in between.  
         [0058]     During movement of the inner rail  2  the locking pin  9  is passed over one of the lead-in and lead-off inclines  19 , as far as the recess  14 , where it locks into the latter. While guiding the locking pin  9  over the lead-in and lead-off inclines  19 , the locking element  10  is slightly elastically pushed outwards. In the version shown, the locking elements are offset vis-à-vis one another, resulting in discrete locking positions at a distance following each other closely, and are equally suitable for rails with front and rear extension.  
         [0059]     At particular points on the path of movement, as shown in  FIGS. 4A and 4B , two locking elements  10  can be arranged horizontally opposite, with the result that, when they engage with the locking pin  4 , they secure the latter from two sides.  
         [0060]      FIGS. 5A  and B show the slide element  3  of the telescopic rail, which has an eccentric brake. In front of the recess  17  in the back wall  18  of the slide element  3 , two elastically mobile brake shoes  11  are shown which are pushed apart during rotation of the eccentric  12  about its axis of rotation, with the result that they come into friction contact with the inner surfaces of the inner rail  2 . Thus the relative displacement between the outer rail  1  and the inner rail  2  is braked and stopped. The eccentric  12  is for example driven via the circular-segment-shaped toothed wheel section  9 .  
         [0061]      FIGS. 6A and 6B  show an eccentric self-locking brake. The brake is secured to the slide element  7  and has two eccentrics  27 ,  28  supported rotatably on pins  29 ,  30  and pre-tensioned with springs  31 ,  32 , the casing surfaces of which are pushed against the inner surface of the inner rail  2 . The shape of the eccentrics  27 ,  28  is designed such that their external radius increases against the direction of movement of the inner rail  2 . If the eccentric  27 ,  28  is in friction contact with the inner rail  2  and the inner rail  2  is moved, the eccentric  27 ,  28  is rotated about the pin  29  or  30  respectively and regions of the eccentric  27 ,  28  with a larger external radius come into friction contact with the inner rail  2 . However, the larger the external radius of the section of the eccentric  27 ,  28  engaging with the inner rail  2 , the greater the clamping effect. Consequently the braking effect is automatically increased when the inner rail is displaced.  
         [0062]     The two eccentrics  27 ,  28 , as shown in  FIGS. 6A ) and  6 B), are arranged running in opposite directions, and having radial symmetry on the slide element  3 . Thus in both possible directions of displacement of the inner rail  2 , the braking effect is increased with displacement. In the version represented, the first eccentric  27  comes into friction contact with the upper slide  7  and the second eccentric with the lower slide  7 . Between the two eccentrics  27 ,  28 , a rotatably supported cam  33  is arranged. This can be rotated via an axle penetrating through the slide element  3  and the outer rail  1 , pressing the cam  33  against the spring tension onto the ends of the eccentrics  27 ,  28  with the result that the latter are rotated and the braking force is reduced or increased.  
         [0063]      FIGS. 7A and 7B  show the so-called sliding brake for braking the displacement movement between the inner  2  and outer rail  1 .  FIG. 7A  clearly shows the slide  13 . The slide  13  has two brake shoes  11 . On the slide  13 , a slide lever  23  is secured which penetrates through an oblong hole  34  in the slide element  7  and the outer rail  1 . This slide lever  23  can be actuated, in order to displace the slide  13  in the direction of the extension. Alternatively, the slide  13  can be carried along by the inner rail  2  when it is displaced, e.g. by an inward projection or a pin, with the result that it is displaced opposite the slide element  3  and the fixed pin  20  secured to it. The slide  13  can then serve as a braked end stop. The pin  20  engages in the oblong hole  21  within the slide  13  and, because of the reducing width of the oblong hole during the displacement of the slide  13 , pushes apart the brake shoes  11 , which are formed by the outer surfaces of the slide  13 . The brake shoes  11  come into friction contact with the inner surfaces of the inner rail  2 , gently braking the displacement of the inner rail  2  relative to the outer rail  1 . Because of the shape of the oblong hole  21  the pin  20  secured on the slide element  7  locks into the end position of the oblong hole  21 , thus retaining the braking effect even after release of the slide lever  23 . Only by displacement of the slide  13  in the opposite direction is the braking effect of the slide  13  removed again.  
         [0064]      FIG. 7B  also clearly shows that the slide element is secured against displacement relative to the outer rail  1  using the pin  21 , which is secured to the outer rail  1  and engages in the hole or recess  22  in the slide element.  
         [0065]      FIGS. 8A and 8B  show an alternative end stop with a holding function. In the region of the end of the slide element  3  a clamp-shaped end-stop  23  is shown, the elastic lead-in inclines of which are arranged in front of the recess  17  in the back wall  18  of the slide element  3 . On reaching the end stop, a pin  4 , which is secured to the inner rail  2 , now pushes the lead-in inclines  19  of the end stop  23  apart and thus locks into the hollow  26  lying behind the lead-in inclines  19  of the end stop.  
         [0066]      FIG. 9  diagrammatically represents the modular construction of the slide element  3  made from individual sections  8 ,  24  and  25 . The section  8  is purely a slide element without additional functions. It is produced in different lengths or put together from various shorter basic elements, with the result that different total lengths of the slide element  3  are achieved. The sections  24  form two end stops, as shown in  FIGS. 8A  and B. The additional section  25  provides the slide element with a braking function. Instead of the pure slide element  8 , a slide element with locking elements could also be used in order to be able to provide discrete locking positions between the end stops. The modular construction makes it possible to produce, with prefabricated, simple basic elements, telescopic rails which have different operational features depending on the requirements profile.  
         [0067]      FIG. 10  shows an alternative embodiment where intermediate rail  35  rides on inner rail  1  (using a slide element  3 ) and in turn intermediate rail  35  holds outer rail  2  which rides on inner rail  35  (also using a slide element  3 ).  FIG. 11  shows another embodiment utilizing an intermediate rail  35  that rides on inner rail  1  (with slide element  3 ) and outer rail  2  in turn rides on intermediate rail  35  (also with a slide element  3 ).