Abstract:
A pull-out guide for a drawer includes a body rail that is to be attached to a furniture body, a drawer rail that is to be attached to the drawer, and a central rail that is movably mounted between the body rail and the drawer rail. At least one carriage having at least one rolling element is mounted in a movable manner between the central rail and the drawer rail. The at least one rolling element runs on at least one support profile of the central rail, and the at least one support profile is arranged as a separate component on the central rail.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns an extension guide for a drawer including a carcass rail to be fixed to a furniture carcass, a drawer rail to be fixed to the drawer, and a central rail mounted movably between the carcass rail and the drawer rail. At least one running carriage having at least one rolling body is mounted displaceably between the central rail and the drawer rail, and the at least one rolling body runs on at least one support profile of the central rail. 
     Such extension guides belong to the state of the art and are described for example in German Utility Model specification DE 20 2009 003 883 U1. In that case, the central rail is shaped so that, viewed in cross-section, it has at both sides two support profiles on which the ball bearings of two running carriages run. In that case, the purpose of the support profiles is to prevent the running carriages from lifting off the central rail and/or to reduce the tilting play which generally occurs in the case of extension guides without a support profile and which occurs due to the relative clearance between the rails and the at least one running carriage. 
     That central rail therefore differs from the shape which is usually found to involve of a U-profile having two vertical legs and a horizontal bar which connects the two vertical legs, in which the deviation involves in particular the bend edges between the two vertical legs and the horizontal bar. 
     A disadvantage in that respect is that production of the central rail and thus the entire extension guide is highly complicated and cost-intensive in comparison with the standard form, by virtue of that specific configuration which requires a special bending process. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to avoid the above-described disadvantages and to provide an extension guide which is less expensive and simplified in comparison with the state of the art. 
     To attain that object, the invention proposes that the at least one support profile is arranged as a separate structural unit on the central rail. 
     The invention is based in particular on the realization that it is only necessary at all under certain circumstances for the central rail to have a support profile to prevent the running carriage from lifting off. More specifically, the weight of the drawer is normally relatively uniformly distributed to the extension guides, so that the risk of lifting off does not arise at all. In those cases, the at least one support profile can be readily omitted and thus material can be saved. If, however, the extension guide is to be used for drawers which for example have a front panel which is very heavy in comparison with the other drawer components and are thus greatly nose-heavy, then the at least one support profile is necessary in particular to avoid the front of the drawer from tipping out in the pushed-in condition of the drawer. 
     Because the at least one support profile according to the invention is a separate structural unit, it is possible for the central rail to be retro-fitted modularly specifically for rather rare special cases, in which respect such retro-fitting can either already be effected at the factory in manufacture of the extension guide, or it can be effected by the user. 
     It should also be noted that the at least one rolling body which runs on the at least one support profile can be a runner, a roller or a ball. 
     To prevent the front of the drawer from tipping out as referred to above in the pushed-in condition of the drawer, preferably two measures can be implemented. The first measure provides that the at least one running carriage engages under the at least one support profile in the position of use of the extension guide with the at least one rolling body to safeguard against being lifted off the central rail. The second measure provides that at least one contact leg is arranged on the drawer rail, and the drawer rail engages under at least one rolling body arranged on the at least one running carriage in the position of use of the extension guide with the at least one contact leg to safeguard against lifting off of the at least one running carriage. If both measures are implemented, then the drawer which is fixed to the drawer rail is prevented by the extension guide from lifting off—to put it in brief terms—by double engagement under the support profile. 
     In an advantageous embodiment of the invention, the at least one support profile extends at least portion-wise in the longitudinal direction of the central rail. To prevent the front of the drawer from tilting out in the pushed-in condition of the drawer or to reduce the tilting play described in the introductory part of this description, it may also be sufficient if the at least one support profile extends in the longitudinal direction only over a partial region of the central rail—expressed in numbers, over a partial region of between 20% and 60%, and preferably over a partial region of between 30% and 40% of the central rail. If precisely two running carriages are mounted displaceably between the central rail and the drawer rail, the at least one support profile can extend in the longitudinal direction only over a rear partial region of the central rail, that is arranged in the proximity of the drawer rear wall, or that partial region of the central rail, in which the second rear running carriage is displaceably mounted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details and advantageous embodiments of the invention are described more fully in the specific description hereinafter with reference to the Figures, in which: 
         FIG. 1 a    is a diagrammatically illustrated perspective view of a drawer box with two drawers in the pushed-in condition, 
         FIG. 1 b    is a diagrammatically illustrated perspective view of the drawer box of  FIG. 1 a   , the upper drawer being in the pulled-out condition and the lower drawer in the pushed-in condition, 
         FIG. 2 a    is a diagrammatically illustrated perspective view of a preferred embodiment of the extension guide according to the invention in the pulled-out condition, 
         FIG. 2 b    is a diagrammatically illustrated perspective view of the preferred embodiment of the extension guide according to the invention in the pushed-together condition, 
         FIG. 3  is a diagrammatically illustrated exploded view of the preferred embodiment of the extension guide according to the invention, and 
         FIG. 4  is a diagrammatically illustrated cross-sectional view from the rear partial region of the preferred embodiment of the extension guide according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 a  and 1 b    show diagrammatically illustrated perspective views of a drawer article of furniture  25  with two drawers  2  arranged one above the other. The two drawers  2  are respectively fixed to the furniture carcass  3  of the drawer article of furniture  25  by two extension guides  1  arranged at right and left sides, and can be pushed into and pulled out of the article of furniture  25  by those extension guides  1 . The two drawers  2  are severely nose-heavy drawers as on the one hand they are of a small depth while on the other hand their front panel  26  is relatively heavy compared to the other drawer components including the drawer rear wall  12 , the two drawer side walls  27 , and the drawer bottom  28 . The two extension guides for the upper drawer, in contrast to the extension guides of the lower drawer, have the support profiles  10  and  11  according to the invention whereby the drawer front  26  in the case of the upper drawer in comparison with the lower drawer is prevented from tipping out in the pushed-in condition of the drawer. 
     The details of the two extension guides  1  of the upper drawer will be described more fully hereinafter by reference to  FIGS. 2 a , 2 b   ,  3  and  4 . In specific terms, a so-called full extension can be implemented with these extension guides  1  (that is to say, the drawer rear wall is in the front plane of the article of furniture when the drawer is in the pulled-out condition). That is achieved by the extension guide  1  comprising three rails, a carcass rail  4  which can be fixed to the furniture carcass by way of holes  49  for receiving screws, a drawer rail  5  to be fixed to the drawer, and a central rail  6  supported movably between the carcass rail  4  and the drawer rail  5 . In the preferred embodiment of the extension guide  1  illustrated, the drawer rail  5  has three per se known particularities. 
     Firstly, mounted laterally to the drawer rail  5  is a damped, spring-assisted retraction device  29  including a force storage member in the form of a spring. That spring is prestressed when the extension guide  1  is pulled out by a pin  31  which is fixed to the carcass rail  4  and which is at the end face of an angle portion  30 . As from a given position when pushing on the extension guide  1 , that pin  31  engages again into a slider which is fixed to the spring and the energy stored in the spring is liberated and causes the extension guide  1  to be completely pulled in over the remaining distance that is still to be covered. So that this movement takes place in a damped fashion, the retraction device  29  includes a damping device which counteracts the force-storing spring. A second particularity of the drawer rail  5  is a height adjusting device  32  which is arranged in the front region and by way of which the front region of the drawer can be adjusted in height. The third particularity is an adjusting device  33  for adjusting the position of the drawer relative to the drawer rail  5 , and the adjusting device  33  is disposed in the rear region of the drawer rail  5 . It includes a holding projection  34  which projects into a corresponding opening in the drawer rear wall. That adjusting device  33  also serves at the same time as a push-in movement limiting means for the drawer. 
     It will be seen from  FIG. 2 a    and from  FIGS. 3 and 4  that the central rail  6  in cross-section is substantially in the form of a U-profile. In the position of use of the extension guide  1 , the U-profile includes two vertical legs  14  and  15  and a horizontal bar  16  which connects the two vertical legs  14  and  15  together. Arranged on each of the two vertical legs  14  and  15  is a respective support profile  10  and  11  in the form of a separate structural unit. It should be pointed out that the angle bend edges between the two vertical legs  14  and  15  and the horizontal bar  16  include an angle α and β respectively of 90°. In cross-section, the two support profiles  10  and  11  are substantially L-shaped, wherein a first limb  17  and  18  of that L-shape respectively bears against a respective one of the two vertical legs  14  and  15 , and the second limb  19  and  20  of the L-shape is oriented perpendicularly to the vertical legs  14  and  15 . Further features of the support profiles  10  and  11  are that:
         they are arranged above a horizontal central plane M of the central rail  6 , which plane is notional in the position of use of the extension guide  1 ,   they extend over a rear partial region T of about 35% in the longitudinal direction L of the central rail  6 ,   they completely consist of metal,   they are fixed (welded) to the central rail  6 , and   they are of an integral configuration.       

     Two running carriages  7  and  35  are supported displaceably between the central rail  6  and the drawer rail  5 , and the support profiles  10  and  11  extend only over the partial region T of the central rail  6 , in which the rear running carriage  7  is displaceably supported. That rear running carriage  7  has two support rollers  8  and  9  which are mounted rotatably laterally in the running carriage cage  39 , and which each run on a respective one of the two support profiles  10  and  11  of the central rail  6 . More precisely, in the position of use of the extension guide  1 , they engage under the support profiles  10  and  11  to prevent lifting off of the central rail  6 . In other words, they run at the downwardly directed side  21  and  22  of the two limbs  19  and  20  of the L-shape of the support profiles  10  and  11 , respectively. It should also be pointed out that the movement of those two support rollers  8  and  9  in the longitudinal direction L of the central rail  6  is limited on the one hand by an abutment  13  arranged on the support profiles  10  and  11 , and on the other hand by an abutment  50  arranged on the central rail  6 . In addition to the two support rollers  8  and  9 , further rolling bodies  36 ,  37  and  38  are mounted rotatably in the running carriage cage  39  of the running carriage  7 , by way of which further rolling bodies the running carriage  7  runs on the two vertical legs  14  and  15  and the horizontal bar  16  of the central rail  6  and against the underside of the drawer rail  5 . The front running carriage  35  is, in principle, of exactly the same structure as the rear running carriage  7 , with the difference that it does not have any support rollers to safeguard against lifting off the central rail  6 . Two running carriages  46  and  48  are also supported displaceably between the central rail  6  and the carcass rail  4 , and those running carriages  46  and  48  are coupled together by way of a coupling device  47 . For the sake of completeness, attention is also directed to a particularity shown in  FIG. 3 . The preferred embodiment of the extension guide  1  according to the invention includes a synchronization device which is known per se from the state of the art and which includes a rack  44  fixed to the drawer rail  5 , a gear  45  fixed to the central rail  6 , and a rack arranged on the running carriages  46  and  48  supported displaceably between the central rail  6  and the carcass rail  4 . This synchronization device provides for synchronization of the movement of the drawer rail  5  relative to the central rail  6 , and the movement of the central rail  6  relative to the running carriages  46  and  48  arranged between the central rail  6  and the carcass rail  4 . 
     If the cross-sectional view shown in  FIG. 4  of the preferred embodiment of the extension guide  1  according to the invention is considered more closely, it can be clearly seen that a shallow bent-over contact leg  23  and  24  is respectively arranged at right and left sides on the drawer rail  5 , the two contact legs  23  and  24  being oriented parallel to the notional horizontal central plane M of the central rail  6 . With those two contact legs  23  and  24 , the drawer rail  5  engages under the support rollers  8  and  9 , respectively, of the rear running carriage  7  and thus prevents the drawer rail  5  from lifting off the running carriage  7 . The running carriage  7  is, in fact, in turn safeguarded against lifting off the central rail  6  by the two support rollers  8  and  9  by virtue of engaging under the support profiles  10  and  11 . It will further be seen that the two lateral support rollers  8  and  9  of the rear running carriage  7  have different diameters D 1  and D 2 , and they are arranged mounted rotatably on the running carriage  7  at different heights. In addition, the two support profiles  10  and  11  are arranged asymmetrically on the two vertical legs  14  and  15  of the central rail  6 . 
     Even if the invention was described in specific terms by means of the illustrated embodiment, it will be appreciated that the subject-matter of the application is not limited to that embodiment. Rather, measures and modifications which serve to implement the concept of the invention are obviously conceivable and desired. Thus, for example, the support profiles in cross-section, instead of being of the L-shape, could be of a different shape, for example being at least region-wise of a circular and/or elliptical configuration, or as the outline of a right-angled triangle. It is also conceivable that the support profiles comprise not (just) metal, but instead (or also) they can comprise plastic or other materials. In addition—besides the above-mentioned possibility of attachment by welding—there are many other different possible ways of fixing the support profiles to the central rail, for example by riveting, screwing or soldering.