Patent Publication Number: US-2011074263-A1

Title: Household appliance with a door comprising a braking device

Description:
The present invention relates to a household appliance, in particular a refrigeration appliance such as a refrigerator, with a door that can tilt about a tilt axis, and with a braking device for damping the tilt motion of the door. 
     In the case of household appliances, in particular such as refrigerators, the provision of so-called door-in-door-solutions is increasingly called for as a means of improving energy efficiency, in which an additional door is provided in the actual door of the refrigerator, such as for example of a refrigerator, in order to enable access to a drinks compartment or to a rack for drinks attached to the inside face of the main doors independently of opening of the “main doors”. As in the case of such solutions it is no longer necessary to open the main doors and warm air can thereby no longer flow into the refrigerator, less cooling power and thus less energy is required overall. 
     In order not to spoil the esthetics of such door-in-door solutions by the addition of a further handle, the smaller door arranged within the main doors is generally provided with a so-called push-push mechanism, in the case of which both opening of the door and its closure by means of simple pressure exerted on the edge region of the door, for example by the hand of a user. A spring is as a rule required for functioning of the push-push mechanism, which effects or at least assists the autonomous opening of the door from its closed position—in opposition to the direction of pressure exerted by the hand. This can, however, lead to problems in that as it is not firmly held by a user by means of a handle, the door performs an uncontrolled and excessively rapid movement. This problem then arises in particular if the tilt axis of the door is arranged horizontally, and the movement of the door increases in force upon opening as a result of gravity. In order to prevent an excessively rapid movement of this kind, U.S. Pat. No. 7,059,693 B2 proposes the attachment of a damping unit to the door, in which a rotating element in an oil-filled container serves to damp the movement of the door. In practice, however, is has proved difficult to mount a damping unit to act on the door, in light of the restricted space available. 
     The present invention is based on the problem of avoiding the problem associated with the prior art, and creating a household appliance, such as, in particular, a refrigerator, in which a damping unit or braking device for damping the tilt motion of the door provided, which not only works reliably, but can also be readily installed, despite the limited space available. 
     This problem is solved with a household appliance according to claim  1 . Advantageous developments of the invention are the subject of the dependent claims. 
     The inventive household appliance comprises a door which can be tilted about a tilt axis and a braking device for damping the tilt motion of the door. The invention is characterized in that a transferring unit for transferring the rotation of the tilt axis to a braking axis during the tilt motion of the door is provided, said braking axis being offset relative to the tilt axis, and that the braking device is here in functional cooperation with the braking axis. In other words the braking device does not act directly on the door, but on the transferring unit. The braking device can thereby be installed in a position optimally tailored to the prevailing space, which would otherwise be particularly difficult to realize in the immediate vicinity of the moving door. It should here be noted that the terms “tilt axis” and “braking axis” should not simply be understood as to refer to the actual physical embodiment of such an axis, for example in the form of a shaft, but that they are to be understood in the abstract sense of the word “axis”. This means that any form of the embodiment of such an axis should be encompassed by these terms, so that the rotational motion of the door is transferred from its tilt axis to another axis designated as the braking axis, and the braking device acts on this braking axis. 
     A particularly simple embodiment of the invention then arises if the tilt axis comprises a pin or for example two pins at the end of the door, and the transferring unit is made up of a multiplicity of toothed wheels, the first of which is connected in a torque-free or non-slip manner with one of the pins and the last of which is connected in a torque-free manner to the braking device. Such an embodiment is easily realizable from the mechanical perspective and cheap to manufacture, as the toothed wheels are available off the shelf and are thus reasonably priced. 
     The braking effect can be apportioned particularly effectively, if the last toothed wheel is placed underneath the first toothed wheel; in other words the last toothed wheel has a greater pitch circle than the first toothed wheel. 
     An alternative possible realization of the transferring unit takes the form of a universal joint, one end of which is connected in a torque-free manner with a pin as part of the tilt axis and whose other end is connected in a torque-free manner to the braking device. 
     It is also possible to embody the transferring unit as a belt drive with two belt pulleys and a belt, in which a first belt pulley is connected in a torque-free manner with one pin as part of the tilt axis and a second belt pulley is connected to the braking device in a torque-free manner. 
     It is particularly preferable to embody the tilt axis in the form of at least one pin connected to the door in a torque-free manner and thereby mounting the door in a pivotable manner on a frame of the household appliance. The transferring unit and the braking device acting on the pin or pins are here located outside the door. 
     It is alternatively possible to arrange the transferring unit and the braking device with the brake within a cavity inside the door. In order then to be able to mount the door on a frame, the at least one pin forming the tilt axis is preferably connected to the frame in a torque-free manner. With this embodiment it is thus possible to use the space within the door to accommodate the transferring unit and the braking device. 
     A particularly expedient application of the invention then emerges if the door is built into an even larger door—also known as a main door—of the household appliance, where the larger door can tilt preferably about a essentially vertically arranged door tilt axis. This larger door is, for example, a “normal” door of a freezer or refrigerator, which is laterally jointed. It is here particularly advantageous if the tilt axis of the small door is essentially horizontally arranged, and the door is thus opened by being swung downwards. In this case “essentially” vertically or horizontally mean only that the precise alignment in a particular orientation is not the critical factor, but that tolerances stemming from manufacture or uneven setting-up of the appliance concerned may apply, without this impairing the functional capability of the invention. 
     The present invention is then simple to realize, if the transferring unit acts upon the tilt axis of the door, and not on a point offset relative to the tilt axis. Accordingly in this embodiment only the rotational movement need be transferred and it is not necessary also to transfer or compensate translation components, as would be the case were the transferring unit to act upon a point outside the tilt axis. 
     A particularly simple, reliably operating and cost-effective braking device is produced by a friction-braked piston movable within a cylinder. Braking devices of this kind are available on the mass market and are, for example, manufactured by ITW-Ateco GmbH. In the case of such braking devices a piston made out of for example Minlon® rotates in a housing manufactured for example from Delrin®, damped by the viscosity of a liquid introduced between the two. 
    
    
     
       Further advantages, features and characteristics of the invention are evident from the following description of an advantageous embodiment of the invention. Where: 
         FIG. 1  shows a three-dimensional representation of an advantageous embodiment of the invention, from the front, 
         FIG. 2  shows a three-dimensional representation of the advantageous embodiment from  FIG. 1 , seen from the side, 
         FIG. 3  shows a front view of the advantageous embodiment from  FIG. 1 , and 
         FIG. 3   a - 3   k  show different components of the embodiment from  FIG. 3 . 
     
    
    
     By way of example of the invention there follows a description of a refrigerator with a side-hinged door, into which is built a smaller, additional door, which can be opened and closed in a pivotable manner about a horizontally arranged tilt axis. 
       FIGS. 1 and 2  show a (small) door  12  of an inventive household appliance or refrigerator. In the door  12  is a pin  15 , which serves as a tilt axis  14 , via which a pin seat  16  is connected to the door  12  in a torque-free manner. The pin  15  is mounted in a frame  40  in are large, side-hinged door  50  in a pivotable manner. This can be opened by means of a push-push mechanism (not shown) at the top end of door  12 . The opening movement of the door  12  is supported by means of a torsion spring  60  (cf.  FIGS. 3 and 3   b ), which acts upon the door  12  in an open position. Upon opening of the door  12 , the pin  15  connected with it in a torque-free manner as well as a first toothed wheel  34  (cf. also  FIG. 2 ) pushed onto the pin in a torque-free manner rotate. According to the representation in  FIG. 2  the first toothed wheel  34  comprises just some teeth  34   a  on one side of the circumference. Of course a multiplicity of teeth can also be present in an area of the circumference or also—if space considerations allow—teeth can be present around the entire circumference. The first toothed wheel  34  intermeshes with a second toothed wheel  35 , which intermeshes with a third toothed wheel  36  , which in turn intermeshes with a fourth, last toothed wheel  37  . The toothed wheels  34 - 37  thus form a transferring unit  30  for transferring a rotational movement of the tilt axis  14  of the door  12  to a braking axis  22 , which at the sane time is also the axis of rotation of the last toothed wheel  37  and is offset relative to the tilt axis  14 . 
     It is evident from  FIG. 1  and.  2  that the toothed wheel  37  has more teeth  37   a  than the first toothed wheel  34  (relative to their respective circumference); in other words the fourth toothed wheel  37  has a greater pitch diameter than the first toothed wheel  34 . As a result of this the rotational movement of the first toothed wheel  34  is stepped down. The effect of the braking device  20  acting on the last toothed wheel  37  or on its axis  22  can thereby be more precisely apportioned than for example would be the case upon translation of the rotational movement of the first toothed wheel  34 . 
     In this embodiment the braking device  20  comprises a piston  28 , which can move in a cylinder  27  and is braked through friction. The piston  28  here has engaging projections  26 , which engage in recesses  37   b  of the last toothed wheel  37  (cf.  FIG. 3   h ) and are thus also rotated upon rotation of the fourth toothed wheel  37 . The cylinder  27  on the other hand is held fixedly and in a torque-free manner by means of a brake holder  24 .  FIG. 3  and the  FIGS. 3   a - 3   k  show individual components of the inventive refrigerator, either assembled or as the case may be represented in individual form. The pin  15  of the door  12  is fixed in a torque-free manner in a pin seat  16 , which forms part of the door. The toothed wheels  34 - 37  are in each case held in a rotatable manner via a bearing flange  38  and a toothed wheel fixing  39 . The torsion spring  60  (cf.  FIG. 3   b ) rests with a first leg  61  on the frame  40  of the door  50 , and engages with a second leg  62  in a corresponding recess  34   b  of the first toothed wheel  34 . 
     By means of the previously described arrangement, upon rotation of the pin  15  connected to the door  12 , this rotational movement, which is forced through opening of the door  12  by means of the torsion spring  60 , is transferred by means of the toothed wheels  34 - 37  from the tilt axis  14  running through the pin  15  to the braking axis  22  running beneath said tilt axis  14 , which passes centrally through the last toothed wheel  37 . The braking device  20  with the piston  28  rotating in the cylinder  27  here lies exactly on the braking axis  22  and thus acts on the rotational movement of the fourth toothed wheel  37  or the braking axis  22  respectively. Through appropriate selection of the pre-tensioning of the torsion spring  60  and the damping characteristics of the braking device  20 , the arrangement can here be configured in such a way that—after the torsion spring  60  ceases to have an effect as the opening movement of the door  12  progresses and the force of gravity exerts an increasingly greater effect as the door opens ever wider—an uncontrolled, excessively rapid downward movement of the door  12  can be avoided. As the braking device  20  does not or need not act directly on the tilt axis  14  of the pin  15  or door  12 , but can also exercise its function on a position offset relative to the tilt axis  14 , where space conditions are correspondingly more favorable in form, the total room available can be better used, and the arrangement optimized. A typical example of the cylinder  27  of the braking device  20  is some 50 mm long and has a diameter of 20 mm. 
     As is evident from  FIGS. 1 and 2  in particular, in the case of the previously described embodiment, the braking device  20 , the transferring unit  30  in the form of the toothed wheels  34 - 37  and the torsion spring  60  and the bearing flange  38  and the toothed wheel fixing  39  are affixed outside the door  12 . It is however also possible to provide a cavity  19  in the door, which is indicated by a dashed line, and to arrange these components within the cavity  19 . That means that these components are moved/pivoted along with the door in the case of a corresponding movement. The space within the door  12  can thereby be used if desired. In this case, though, the pin  15  must be connected in a torque-free manner to the frame  40  fixedly connected with the large door  50 , so that the transferring unit rotates relative to the pin  15 . The functionality of the braking device  20  connected via the toothed wheels  34 - 37  is however not thereby impaired. 
     The frame  40  can be embodied in such a way that it forms a housing  42  (cf.  FIG. 2 ), which can be closed by means of a cover (not shown). This housing  42  can then be cast round with foam material in the course of the production process for the household appliances, in order to improve the insulation effect of the doors  50 , in which the housing  42  is located. 
     Instead of embodying the transferring unit  30  already described in the form of toothed wheels  34 - 37 , a universal joint or a belt drive with two or more belt pulleys and corresponding belts can also be provided, whereby in an appropriate manner the rotational or tilt motion of the door  12  can be transferred from its tilt axis  14  to a braking axis  22  at a distance from this. 
     For practical purposes, diecast zinc should be mentioned as a particularly suitable material for the first toothed wheel  34 , while the remaining toothed wheels and the other components are preferably manufactured from POM (polyoxymethylene). These components can of course also be produced from milled steel parts or appropriate plastics, if applicable reinforced with glass fiber. 
     A refrigerator with left-hinged large door and bottom-hinged small door was previously specified as an example of a household appliance according to the invention. The invention can of course also be used in other types of household appliances, in which such a door-in-door or similar arrangement is desired. 
     It should be recorded that the features of the invention, such as for example the design, shape and material of the transferring unit and the braking device as well as their arrangement described with reference to the embodiment represented can also be present in the case of other embodiments, except if otherwise specified or not feasible on technical grounds. 
     LIST OF REFERENCE CHARACTERS 
     
         
           12 =(Small) door 
           14 =Tilt axis 
           15 =Pin 
           16 =Pin seat 
           19 =Cavity 
           20 =Braking device 
           22 =Braking axis 
           24 =Brake holder 
           26 =Catch projection 
           27 =Cylinder 
           28 =Piston 
           30 =Transferring unit 
           34 =First toothed wheel  20   
           34   a =Tooth 
           34   b =Recess 
           35 =Second toothed wheel 
           36 =Third toothed wheel 
           37 =Fourth toothed wheel 
           37   a =Tooth 
           37   b =Recess 
           38 =Bearing flange 
           39 =Toothed wheel fixing 
           40 =Frame 
           42 =Housing 
           50 =(Large) doors 
           60 =Torsion spring 
           61 =First leg 
           62 =Second leg