Abstract:
The invention describes a bell buckle ( 10 ) for a vehicle seat belt comprising a casing ( 12 ) in which at least one locking element ( 16 ) adapted to lock a plug-in tongue insertable into the belt buckle ( 10 ) and an ejection element ( 18 ) adapted to eject the plug-in tongue are provided. Each of the ejection element ( 18 ) and the locking element ( 16 ) is adapted to adopt a locked position and a home position, wherein in the home position the locking element ( 16 ) is adjacent to the ejection element ( 18 ) and thus is blocked.

Description:
RELATED APPLICATIONS 
       [0001]    This application corresponds to PCT/EP2014/003127, filed Nov. 24, 2014, which claims the benefit of German Application No. 10 2013 020 618.9, filed Dec. 2, 2013, the subject matter of which are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a belt buckle for a vehicle seat belt. 
         [0003]    A belt buckle is configured to receive and to lock a plug-in tongue arranged on a vehicle seat belt so as to prevent the plug-in tongue from being withdrawn from the belt buckle. For this purpose, the belt buckle includes a locking element adapted to interact with a recess within the plug-in tongue and thus locking the plug-in tongue inside the belt buckle. For transferring the locking element from a home position in which the plug-in tongue is not inserted to a locking position in which the plug-in tongue is inserted and locked, a locking mechanism being triggered by the plug-in tongue during insertion is provided. During insertion the plug-in tongue enters into contact with an ejection element disposed in the belt buckle and displaces the ejection element inside the belt buckle. The plug-in tongue is guided inside the belt buckle by the ejection element. 
         [0004]    In the state of the art the ejection element typically includes activating springs triggering the locking mechanism when the plug-in tongue is inserted and accordingly the ejection element is displaced. Hence the locking element is released inside the casing and is displaced so that it engages in the recess of the plug-in tongue so as to inhibit the latter. 
         [0005]    For releasing the plug-in tongue a release push-button is pressed. In this way the locking element is reset into the home position again, thus causing the plug-in tongue to be released again. Then the latter will be ejected from the belt buckle via the ejection element. 
         [0006]    In the known belt buckles it has turned out to be a drawback that a clicking noise of the activating springs and a locking noise of definitely metallic nature will occur by the triggering of the locking mechanism via the activating springs and the locking by the locking element. 
       SUMMARY OF THE INVENTION 
       [0007]    Therefore it is the object of the invention to design a belt buckle in such way that the noise during locking the belt buckle is reduced. 
         [0008]    The object of the invention is achieved by a belt buckle for a vehicle seat belt comprising a frame in which at least one locking element adapted to lock a plug-in tongue insertable into the belt buckle and an ejection element adapted to eject the plug-in tongue are provided, wherein each of the ejection element and the locking element is adapted to adopt a locked position and a home position, the locking element being adjacent to the ejection element in the home position and thus being blocked in its home position. The principal idea of the invention consists in minimizing the noise occurring during locking by reducing the velocity of the locking element during locking. This will work due to the fact that the distance of the locking element from the home position to the locked position is minimized, as the locking element is directly adjacent to the ejection element. The lower velocity entails lower impact energy so that the noise occurring during locking is reduced. Moreover, a simpler structure is resulting as no complicated mechanism has to be provided for retaining the locking element in the home position. There is simply used the ejection element to retain the locking element in the home position. 
         [0009]    Another aspect of the invention provides that the ejection element can be transferred by the plug-in tongue to the looked position in which the election element releases the locking element so that the locking element can reach the looked position and latch the plug-in tongue. According to the locking mechanism no activating springs triggering the locking mechanism are required at the ejection element. The clicking noise otherwise typically generated by the activating springs does not exist, causing the noise occurring altogether during locking to be further reduced. In addition, the assembly of the belt buckle is simplified, because the release mechanism for the looking element is definitely facilitated. 
         [0010]    According to another aspect of the invention it is provided that the ejection element and/or the locking member are biased via a spring element, especially that the locking element is biased against the election element. It is ensured by the bias that the locking element, if released, passes into its locked position so as to guarantee safe latching of the plug-in tongue inside the belt buckle. This is independent of the mounting position of the belt buckle. Via the bias of the election element the inserted plug-in tongue may be ejected from the belt buckle in a simple manner. 
         [0011]    Another aspect of the invention provides that the ejection element includes a web to which the locking element is adjacent in the home position. The length of the web allows adjusting when the locking element is released by the ejection element and passes to the locked position especially due to the bias. The web provided at the ejection element is typically configured corresponding to the length from the end of the plug-in tongue to the recess within the plug-in tongue so that the locking element can directly engage in the recess as soon as it is no longer retained in the home position by the ejection element. 
         [0012]    Especially the ejection element substantially includes an H-shaped cross-section. The ejection element includes two webs connected approximately in the center by a cross web. At said cross web a stop surface for the plug-in tongue and, on the opposite side, a support surface for the spring element biasing the ejection element may be formed. 
         [0013]    Another aspect of the invention provides a damping element adapted to interact with the locking element, especially by decelerating the movement of the locking element in a damping manner. The additional damping element causes the locking element to be decelerated in a comparatively smooth manner at the end of its adjustment travel from the home position into the locking position thereby the locking noise being further reduced. 
         [0014]    According to an aspect of the invention, the damping element is arranged on a casing, especially on an inner surface of the casing. This facilitates the damping of the locking element, as the noise occurring during locking is mainly developed by interaction of the locking element and the casing. 
         [0015]    Another aspect provides that the damping element is provided in an indentation in the casing, especially in an indentation facing the locking element. It is achieved in this way that the locking element directly impinges on the damping element when it passes into its locked position, thus causing the movement of the locking element to be decelerated and the locking element not to impinge on the casing. It is moreover ensured by the arrangement within the indentation that the ejection element may move unobstructed in the belt buckle. 
         [0016]    According to an aspect of the invention, the damping element is a rubber or foam element, especially a PU foam element. These materials are especially well suited for decelerating the impact energy of the locking element and for simultaneously reducing noise. 
         [0017]    Especially the damping element is formed of an injection-molded material that has been injected directly into the casing. In this way the damping element can be configured in a simple way during manufacture of the belt buckle casing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0018]    Further characteristics and advantages of the invention will be evident from the following description and the drawings which are referred to and in which: 
           [0019]      FIG. 1  shows a cross-sectional view of a belt buckle according to the invention in the home position; 
           [0020]      FIG. 2  shows the ejection element, 
           [0021]      FIG. 3  shows another cross-sectional view of the belt buckle according to the invention in a first intermediate position while a plug-in tongue is inserted, 
           [0022]      FIG. 4  shows another cross-sectional view of the belt buckle according to the invention in a second intermediate position with the plug-in tongue being further inserted, and 
           [0023]      FIG. 5  shows the belt buckle of  FIG. 1  with a plug-in tongue being locked therein. 
       
    
    
     DESCRIPTION 
       [0024]    In  FIG. 1  a belt buckle  10  is shown in a cross-sectional view in its home position. The belt buckle  10  includes a casing  12  formed of two casing shells  12   a,    12   b.  In the casing  12   a  locking mechanism is provided in a frame  14  constituting the self-supporting structure of the belt buckle  10 . The locking mechanism comprises at least one locking element  16  as well as one election element  18 . 
         [0025]    The ejection element  18  illustrated in detail in  FIG. 2  is arranged to be movable within the frame  14  and serves for ejecting a plug-in tongue inserted in the belt buckle from the same after pressing a release button at the belt buckle. For this purpose, the ejection element  18  interacts with a spring element  20  which loads the former into its home position (to the left in  FIG. 1 ). The spring element  20  rests on a support surface  22  of the ejection element  18  and is supported on a casing part  23 . 
         [0026]    A stop surface  24  serving as stop for a plug-in tongue not shown here is formed at the ejection element  18  opposite to the support surface  22 . The ejection element  18  further includes two webs  26 ,  28  projecting from the stop surface  24  while facing each other. When a plug-in tongue is inserted in the belt buckle, its front end is located between the two webs  26 ,  28 . 
         [0027]    One of the two webs  28 ,  28  is assigned to the locking element  16  so that it retains the locking element  16  in the home position when the ejection element  18  is provided in the home position. 
         [0028]    On the front end of the webs  26 ,  28  ramp-like bearing surfaces  26   a,    28   a  are formed. The webs  26 ,  28  in total have a pitch circle cross-section, wherein the surface assigned to the stop face  24  is planar. 
         [0029]    The spring element  20  is adjacent the ejection element  18 , namely at the bottom of a receiving sleeve  29  which is integrally formed with the ejection element  18  on the side feeing away from the webs  26 ,  28 . The webs  26 ,  28  directly merge with the wall of the receiving sleeve  29  which receives the spring element  20 . 
         [0030]    The locking element  16 , too, is biased into its looked position by means of a spring, namely by means of a spring element  30  ( FIGS. 3 to 5 ). By virtue of the bias the locking element  16  is pressed against the web  28  of the ejection element  18  assigned to the locking element  16  so that the locking element  16  is in direct contact with the ejection element  18 . The locking element  16  is retained in its home position against the bias by the ejection element  18 . For the purpose of contact the locking element  16  exhibits a contact face  31  that is inclined relative to its longitudinal orientation ( FIG. 2 ). 
         [0031]    The spring element  30  may be in the form of a spiral spring, leaf spring or resilient member. In the illustrated embodiment the spring element  30  is in the form of a resilient metal strip. 
         [0032]    Furthermore, a damping element  32  arranged in an indentation  34  of the casing shell  12   b  is provided within the casing  12 . The damping element  32  is positioned opposite to the locking element  16 , wherein, in the home position of the belt buckle  10 , the ejection element  18  is located between the locking element  16  and the damping element  32 . 
         [0033]    The damping element  32  may be a rubber or foam element which may have been injected into the indentation  34  during manufacture of the casing shell  12   b.  As an alternative, it is provided that the damping element is in the form of an insertion member being glued into the casing shell. 
         [0034]    When inserting a plug-in tongue  36  ( FIGS. 3 to 5 ) the front end  38  of the plug-in tongue provided with a recess  40  for the locking element  16  enters into contact with the ejection element  18 , causing it to be displaced by the plug-in tongue  36  inside the casing  12 . In this way, the belt buckle  10  in general, the locking element  16  and the ejection element  18  are transferred from their home positions into their locked positions as shown in  FIG. 5 . 
         [0035]    The belt buckle further includes, for releasing the plug-in tongue  36 , a push-button  42  adapted to be actuated for moving the locking element  16  via a link guide  44  against the bias of the spring element  30 . 
         [0036]    The transition from the home position ( FIG. 1 ) to the locked position ( FIG. 5 ) takes place as follows, wherein the  FIGS. 3 and 4  illustrate intermediate positions representing a sectional plane different from that of  FIGS. 1 and 2 : 
         [0037]    The plug-in tongue  36  is inserted into the belt buckle  10  ( FIG. 3 ). The plug-in tongue  36  enters into contact with the end  38  at the stop face  24  of the ejection element  18  and then pushes the election element  18  inside the belt buckle  10  to the right toward the casing part  23 . 
         [0038]    During displacement of the ejection element  18  within the belt buckle  10  the spring element  20  arranged at the ejection element  18  is compressed. The locking element  16  first continues being adjacent to the ejection element  18 , especially to the web  28 , during displacement of the ejection element  18 . 
         [0039]    When the election element  18  is displaced so far that the looking element  16  has arrived at the end of the web  28 , the looking element  16  slides over the contact face  31  inclined relative to its longitudinal orientation along the end of the web  28  into its locked position ( FIGS. 3 and 4 ). The sliding is further improved by the fact that the ramp-like bearing surface  28   a  is configured to correspond to the contact face  31  at the end of the web  28  so that smooth sliding of the locking element  16  is resulting. 
         [0040]    After the locking element  16  has slipped along the end of the web  28 , it is pressed through the recess  40  which then is arranged below the locking element  16  by the spring element  30  so that the plug-in tongue  38  is locked in the belt buckle  10 . 
         [0041]    This movement is ensured by virtue of the bias by the spring element  30  so that it takes place independently of the mounting position. The movement of the locking element  16  during locking is reduced by the sliding at the end of the web  28  as, compared to the state of the art, the distance covered by the locking element  18  from the home position into the locked position without deceleration and under the effect of the spring element  30  is reduced. In this way the impact energy of the locking element arriving at the locked position is reduced. Thus the related noise is reduced. 
         [0042]    At the end of the stroke into the locked position, the locking element  16  impinges on the damping element  32 , thus causing the impact energy to be partly taken up and absorbed by the damping element  32 . The occurring noise is further reduced in this way as the locking element  16  does not directly impinge on the casing  12 . 
         [0043]    Upon actuation of the push-button  42  the locking element is moved over the link guide  44  and is disengaged from the recess  40  of the plug-in tongue  36  again. Due to the bias of the spring element  20 , then the ejection element  18  is loaded into its home position ( FIG. 1 ) again and the socking element  16  is adjacent to the ejection element  18 .