Patent Publication Number: US-6659513-B1

Title: Closure for connecting two thin walls

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of International Application No. PCT/EP00/10613, filed Oct. 27, 2000 and German Application No. 299 22 195.4, filed Dec. 17, 1999, the complete disclosures of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     a) Field of the Invention 
     The invention is directed to a closure for connecting two thin walls, such as sheet metal cabinet doors to sheet metal cabinet frames, which comprises a bearing piece, mounted in or on an opening in the first thin wall and a shaft, retained in the bearing piece wherein it may be rotated and axially displaced. A pivoting lever is mounted on the one, outer end of the shaft and, on the other, inner end of the shaft, a retaining piece is arranged, wherein the pivoting lever can be pivoted from a first, open position where the shaft is in a first axially loaded position into a second, closed position where the shaft has been displaced axially outwards against the force of a spring. 
     b) Description of the Related Art 
     Such a closure is already known, cf. for example DE 44 23 406 A1. 
     The object referred to as an “Ausbauchverschluss” (convex or bellying closure) in this document makes it possible to secure two plate-like parts to each other or one plate-like part to a corresponding frame. The closure described in this document has the advantage of great simplicity, since it needs relatively few parts and can be fitted relatively simply. 
     Nonetheless, it also has disadvantages that forbid its use for certain applications. Especially when the closure is supposed to work at low temperatures, as they are for example present in refrigerating chambers, resulting in the disadvantage that the body of expanded material, which for example consists of elastic rubber or plastic, loses its elasticity because of the low temperature and could even break if this leads to brittleness. 
     There is the further disadvantage that the closure is immediately open completely when the operating lever is swung open accidentally, so that there is a risk that the two thin walls move apart unintentionally, which can for example lead to a refrigerating chamber being opened unintentionally. 
     OBJECT OF THE INVENTION 
     It is the primary object of the invention to improve a closure of the type described in the opening section in such a way that the described disadvantages no longer occur. 
     In accordance with the invention, this object is met by making the retaining piece comprise a cupular guide piece and a sleeve piece, which may be inserted in and rotated in the cupular guide piece against the force of a spring. A catch projects from said sleeve piece in the direction of the wall plane which, in the engaged position, extends beyond the outer surface of the guide piece as far as the rear surface of the second thin wall and rests thereon. 
     First of all, these features avoid the use of a body of expanded material, which at low temperatures might not be sufficiently flexible anymore and therefore might lose its function or break during attempts of use because of brittleness, and the ability of the two connected walls to move completely away from each other when the pivoting operating lever is swung away is also removed. When the operating lever of the closure according to the invention is merely swung open, the closure is opened and the connection of the two walls is loosened, but the two walls can not be separated from each other; for this, the lever handle must additionally be rotated, for example by 180 degrees. 
     Whereas in prior art the spring forces and locking forces must be generated by the body of expanded material, resulting in the described disadvantages at low temperatures, the novel closure according to a further development of the invention has the spring force being generated by a spiral spring arranged between the bottom of the cup of the guide piece on one side and on the face of the sleeve facing the bottom of the cup on the other side. This spring is largely independent of temperature influences. 
     So that as in prior art the construction and installation are as simple as possible, it is advantageous if the opening in the second thin wall is circular with two widening sections (for example corresponding to the cross-section of a two-way key) and if the catch part can be slid through the opening like a bayonet in one rotary position of the rotating sleeve part but not in another position, for example one rotated by 90 degrees. 
     If one wants to avoid the expense of producing a two-way key opening in the door-frame, according to another embodiment form the shaft could be guided through the bottom of the cup in a location that is eccentric relative to the circumference of the cup. This makes it possible for the catch to engage behind the wall in a first rotary position, while in a second rotary position the catch can be passed through the opening. 
     According to yet another embodiment form of the invention, the lever can form a cam surface that rests on the outer face of the bearing piece. For prior art, the corresponding support is formed by the thin wall itself, which simplifies construction, but on the other hand can lead to unsightly paint damage that can lead to the formation of rust in visible places. 
     The outer face of the bearing piece can form a groove shaped like part of a circle or a conical depression into which lugs, carried or formed by the lever, extend during its closing pivoting movement. This makes it possible to only allow the closing pivoting movement of the lever in such a position that is optimally suitable, whereas in other positions the pivoting of the lever is not possible because of the lack of a grooved area. This has the advantage that a closing pivoting movement is only possible in a position where the catch engages sufficiently safely behind the second wall. 
     According to yet another embodiment of the invention, the sleeve carrying the catch is held on the shaft by a self-locking nut. This has the advantage that the closing force can be set as required by way of screwing the nut further onto or off the bolt. 
     According to yet another embodiment of the invention, it can also be advantageous to place a spring washer between the self-locking nut and the catch sleeve for the purpose of compensating for small differences in tolerance. 
     According to yet another embodiment of the invention, it is advantageous for the outside of the bottom of the cupular part to have a projection which is matched by a correspondingly shaped opening in the thin wall in such a way that the cupular part is secured against rotation relative to the thin wall; this is to ensure that the cupular part does not twist relative to the thin wall and in so doing makes a closing position indefinable. 
     The projection could in particular have a non-round cross-section which fits into an opening in the thin wall which also has a non-round cross-section and thus is secured against twisting. 
     Alternatively, the thin wall could also have additional openings into which lugs coming from the bearing protrude, but this does require additional openings in the thin wall, which sometimes are impractical. 
     Instead of the lug or the several lugs, threaded boreholes can be provided into which (countersunk head-) screws can be screwed which come from the bearing or which can be passed through corresponding boreholes in the bearing. 
     This design is particularly tamper-proof. 
     A simple construction is made possible when according to another further development of the invention the opening in the first wall is an elongated hole into which the cross-section of the shaft fits essentially without any play. By this, securing it against rotation is achieved without additional boreholes, and the opportunity for adapting to different conditions also exists. 
     This is in particular the case if the opening in the first wall is an elongated hole into which the cross-section fits with play. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is subsequently to be described in more detail by means of embodiment examples shown in the drawings. 
     FIG. 1 shows an exploded view of an embodiment form of the closure for the connection of two thin walls according to the invention, which here are a sheet metal cabinet door and a sheet metal cabinet frame; 
     FIG. 2 shows a cross-sectional view whose sectional plane is close to the outside surface of the first thin wall; 
     FIG. 3 shows in a representation similar to FIG. 2 an alternative embodiment form of the closure according to the invention which is secured against rotation by means of an elongated hole so that additional boreholes in the door leaf are not necessary; 
     FIG. 4 shows a cross-sectional view similar to FIG. 2 for the representation of an embodiment form; 
     FIG. 5 shows a view similar to FIG. 4 for the representation of another embodiment form; 
     FIG. 6 shows a perspective view of the arrangement according to FIG. 3, but in the assembled state, wherein the closure can be seen in the swung open position; 
     FIG. 7 shows a perspective view of the closure shown in FIG. 6 but with the handle swung in; 
     FIG. 8 shows the handle according to the invention in partial FIGS. A, B, C and D, wherein the different partial Figures show different phases of opening: 
     FIG. 8A shows the closure in the closed position; 
     FIG. 8B shows the lever handle swung up and consequently the loosened closure; 
     In FIG. 8C, the handle has been rotated by 180 degrees so that according to FIG. 8D the two thin walls can be separated from each other and, for example, the door leaf can be swung away from the door frame. 
     FIG. 9 shows the bearing piece of the closure according to FIG. 3 in a view from above; 
     FIG. 10 shows a closure according to another, bayonet-like embodiment form in the closed position in a side view; 
     FIG. 11 shows the closure from FIG. 10 in a partially sectional view in the opened position; and 
     FIG. 12 shows diagrammatically the two-way key form of the opening in the second wall (door frame) and the matching retaining part in the opened and closed position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows an exploded view of a closure  10  with which two thin walls, like for example a sheet metal cabinet door  12  and a sheet metal cabinet frame  14  can be connected. 
     The closure comprises a bearing piece  18  arranged in or on an opening  16  in the first thin wall  12  and a shaft  20 , retained in the bearing piece wherein it may be rotated and axially displaced. A pivoting lever  24 , which can be pivoted on an axis  28  that is vertical to the axis  26  of the shaft  20  is mounted on the one outer end  22  of the shaft  20 , for example held by a pin  30 , which on one side is inserted in a borehole  32  in the jointed end of the lever  24  and on the other side is inserted in a transverse bore  34  on the end of the shaft  20  and which is secured appropriately. 
     On the other, inner end  36  of the shaft  20 , a retaining piece  38  is arranged, wherein the pivoting lever  24  can be pivoted from its first, open position, for example shown in FIG. 6, where the shaft is in a first axial thrust exerting position, into a second, closed position—cf. FIG.  7 —where the shaft is displaced axially outward (towards the pivoting lever  24 ) against the force of a spring  40 . 
     The retaining piece  38  comprises a cupular guide piece  42  and a sleeve piece  44 , which may be inserted and rotated in the cupular guide piece  42  against the force of a spring  40 ; a catch  46  bent back towards the wall plane  50  projects from said sleeve piece  44  and, in the locked position, extends beyond the outer surface  48  of the guide piece  42  as far as the rear surface  50  of the second thin wall  14  and rests thereon, cf. for example FIG.  7  and FIG.  8 A. 
     As already mentioned, the spring force is generated by a spring  40  which has been slid onto the shaft  20  and which can be arranged between the bottom of the cup (not shown) on one side and the annular face  52  of the sleeve  44  facing the bottom of the cup. The annular face could here also have a ring-shaped groove into which part of the spring penetrates, giving it a greater longitudinal extent, so that the spring effect of the pressure spring  40  can be more even. 
     From the cup-bottom of the cupular guide piece  42  a projection  55  protrudes (cf. FIG. 3) which on one side delimits the opening  56  provided in the cup-bottom for the shaft  26  in such a way that together they result in an elongated, non-round cross-section, cf. the cross-section according to FIG.  2 . This joint oval, elongated cross-section has a bisecting line  58  which defines a center line and which varies from a corresponding bisecting line  60  of the cross-section  56  of the shaft  20  by a certain quantity  62 . When assembled, the two cross-sections  54 ,  56  are housed by an opening  64  in the bearing piece  18  which is also non-round and of a matching shape. In consequence, the shaft  20  is arranged eccentrically by the quantity  62  relative to the bearing piece  18  and the guide piece  42  housed by it. This has the consequence that in the position of the lever to be seen in the FIGS. 8A and 8B the catch protrudes beyond the outside wall  48  of the guide piece  42  by a distance which is roughly equivalent to double the eccentricity  62 ; but in a direction 180 degrees opposite to this (cf. FIGS.  8 C and  8 D), it is flush with this outside wall, so that in this position the two pieces  42  and  46  can be passed through the opening  66  which is slightly larger than the cupular component  42  so that according to FIG. 8D the thin wall  14 , which is for example the door frame, can be separated from the wall  12 , which is for example the door leaf; cf. the arrow  68  in FIG.  8 D. 
     To ensure that for a rotating movement of the lever handle  24  (cf. the arrow  70  according to FIG. 8C) the eccentric movement between the sleeve piece  44  holding the catch  46  on one side and the guide piece  42  guiding the sleeve  44  on the other side actually occurs, it must be ensured that the sleeve piece  44  can not twist relative to the door leaf or the thin wall  12 . According to the embodiment form in FIG. 1, this is done by holding the projection (together with the shaft  20 ) in the corresponding non-round cross-section of the bearing piece  18  in such a way that a torsion-proof connection results between the components  42  and  18 . In turn, the piece  18  can be connected to the door leaf  12  in a manner that is torsion-proof; for example by means of additional openings  72 ,  74  in the thin wall through which either toes  78  projecting from the supporting surface  76  of the bearing piece  18  on the thin wall  12  are inserted into boreholes  72 ,  74 , or by fixing screws  80  coming from the bearing surface  76  in threaded boreholes, wherein in turn the cap screws  80  may be guided through the openings  72  or  74 . 
     For this type of attachment, it does not matter what shape the opening  16  has, as long as there is a sufficient amount of space for the passage of the joint cross-section of the shaft  20  and the projection  55 , cf. FIG.  2 . 
     Nonetheless, according to FIGS. 3 and 4, the design is such that the opening  116  has exactly the same shape as the cross-section of the projection and the shaft so that here the bore itself makes a securing against rotation possible. By means of this, additional component parts like projections  78  and screws  80  are no longer necessary. The need for corresponding openings  72 ,  74  in the door leaf  112  also no longer applies. 
     Even if there is some residual play between this cross-section and the corresponding opening  216  according to FIG. 5, in particular in direction of the axis  83  according to FIG. 5, the elongated shape of the joint cross-section of shaft and projection prevents twisting inside this elongated borehole  216 ; on the other hand, a movement inside this elongated borehole  216  along its longitudinal axis is made possible; this can be advantageous for certain applications, for example when the door  112  and the door frame  114  have been warped relative to each other so that the two openings  116  and  216  do not align with each other exactly any more. This makes closing the arrangement easier; what also makes the closing process easier is the fact that the catch  46  shown in FIG. 3 on the one hand and a corresponding portion  84  of the guide piece  42  on the other hand are shaped like a cone. 
     As can be gathered from the Figures, the lever  24  forms a cam surface  86  which rests on the outer face  88  of the bearing piece  18 . As it is known in the art, this cam surface  86  has such a shape relative to the axis  28  that the desired traction movement results during the pivoting of the lever  24 . To ensure that the closing movement of the lever  24 , meaning the movement from the position according to FIG. 8A to the one according to FIG. 8B, arrow  90 , can only take place when the catch  46  is in the protruding position according to FIG. 8B, provisions have been made for the outer face  88  of the bearing piece to form a groove shaped like part of a circle or a depression  92  into which a lug  94  carried or formed by the lever  24  extends during its closing pivoting movement, cf. FIGS. 6 and 7. By means of this, the inwards pivoting movement for tightening the closure and therefore for pressing the catch against the inside surface of the thin wall  14  can only take place in a position where the catch front face can actually grip this wall; this is the position shown in FIG.  8 B. 
     Because the lug forms an obstruction, the absence of the depression or of the groove formed like part of a circle prevents the inward pivoting of the lever  24  if the lever handle  24  is not in this optimal position. 
     What also should be mentioned is the flattened portion  96  on the end of the shaft  20  which can be made out in FIG.  1  and which facilitates its improved guidance between the side walls  98  of the slit formed by the lever  24 . 
     A ring-shaped groove  100  in the shaft  20 , which also can be made out in FIG. 1, can be used for providing an O-ring seal  101 . The other end  36  of the shaft  20  has a peripheral thread  102 , also with a flattened portion  103 , so that a torsion-proof attachment of the sleeve piece  44  is made possible because of a correspondingly shaped non-round opening  104 , while the self-locking nut  105  makes setting the tightness of the closure possible. If one then arranges a spring washer  106  between the self-locking nut on one side and the sleeve piece  44  on the other side, tolerances of, for example, the thickness of the walls  112 ,  114 , can be compensated for; cf. FIG.  3 . 
     FIG. 9 shows the groove shaped like part of a circle  52 , here in the shape of a short depression with wedge-shaped walls, into which a corresponding wedge-shape of the projection  94  fits precisely. 
     The wedge-shape ensures that the inward pivoting movement requires no great effort, even when the lever  24  is not aligned precisely. 
     According to FIG. 3, a groove  107  has been made in the surface with which the bearing piece  118  rests on the thin wall  112  into which an O-ring seal  108  can be inserted. If additionally the aforementioned sealing washer  101  is provided in the groove  100 , the arrangement is made waterproof by means of this. 
     FIG. 10 shows the side view of a closure  110  according to another, bayonet-like embodiment form in the closed position, while FIG. 11 shows the closure  110  in a partially sectional view in the opened position. The first thin wall  112  and the second thin wall  114  here have round holes of the same size, but the round hole in the second thin wall has additionally been provided with two wider portions lying opposite to each other (for example, corresponding to the cross-section of a two-way key), so that in one rotary position of the rotating sleeve  144 , the catch  146  can be passed through the opening like a bayonet, but not in another position which, for example, is offset by a rotation of 90 degrees. 
     Here also, the bearing piece  118  is screwed to the first thin wall  112  by means of countersunk head screws  180 ; the other parts are also provided analogously, as can be gathered from the references to which the prefix “1” has been added. 
     FIG. 12 shows diagrammatically the two-way key shape of the opening in the second thin wall (doorframe)  114  and the matching retaining piece  138 , in the opened and in the closed position. 
     Although the expense at which the two-way key opening in the door frame is produced is a little bit higher than for a plain round opening like the one according to the embodiment form in FIG. 1, the shape of the closure is on the other hand a little bit simpler. 
     The invention can be applied industrially in the field of switch cabinet construction. 
     While the foregoing description and drawings represent the present invention, it will be obvious to those skilled in the art that various changes may be made therein without departing from the true spirit and scope of the present invention.