Abstract:
A lock, especially for motor vehicles, for securing a movable part, such as a pivoting flap, in position with respect to a stationary part, such as a housing, includes two rotary latches at a certain distance apart, wherein two closing pieces engage in the rotary latches when the latches are in the closed position. The locking elements are connected to a shaft and are rotatable synchronously with the shaft. At least certain sections of the shaft have torsional rigidity in the rotational direction, but flexibility in the axial direction.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention pertains to a lock, especially for motor vehicles, for securing a movable part, such as a pivoting flap, in position with respect to a stationary part, such as a housing. The lock includes two rotary latches arranged at a certain distance apart, in which two closing pieces engage when the latches are in the closed position. Two locking elements hold the two rotary latches in their closed position and are designed as integral parts of the shaft connecting them to each other, so that the locking elements are able to rotate synchronously with the shaft. In their closed position, the two rotary latches cooperate with two closing pieces. The latches are secured in their closed position by two locking elements, which are designed as integral parts of the shaft which connects them to each other. These elements are thus able to rotate synchronously with the shaft.  
           [0003]    2. Description of the Related Art  
           [0004]    In a known lock of this type, the two locking levers are designed as integral parts of the die-cast zinc shaft which synchronizes them. As a result of manufacturing processes and later as a result of fluctuations in temperature during use, angle tolerances and distortions develop, which can make it difficult to operate the lock as intended. These factors can also lead to twisting after the shaft has been installed, which can cause jamming.  
         SUMMARY OF THE INVENTION  
         [0005]    The invention is based on the task of developing a lock of the type indicated above, which is characterized by a high degree of operating reliability.  
           [0006]    This is achieved according to the invention by providing at least certain sections of the shaft with torsional rigidity in the rotational direction, but with flexibility in the axial direction.  
           [0007]    The flexibility of the shaft or of at least one section of it provides compensation for tolerances, which can increase significantly under certain conditions during later use, depending on the amount of heat to which the shaft has been subjected. The synchronization of the two locking levers is nevertheless still ensured as a result of the good torsional rigidity of the shaft according to the invention. The one-piece design according to the invention of the shaft and the two locking levers represents a “combination” which allows the use of plastic. This has a favorable effect on the weight and on the price of the lock. The flexibility of the shaft, furthermore, is highly advantageous with respect to installation of the one-piece combination according to the invention in its bearings.  
           [0008]    With respect to the shaft, this special combination according to the invention can be achieved by an alternating sequence of rigid and flexible axial sections. One possibility of realizing this is to make these two types of axial sections out of two different materials, namely, a material which bends easily and a material of greater strength. Both materials consist of plastic, and the combination of the two is created during the injection-molding process.  
           [0009]    It has been found, however, that another possibility is especially advantageous, which consists in using the same material to make both of the two different axial sections of the shaft and in providing the two different axial sections with different profiles. Ways in which this idea can be realized in detail can be derived from the subclaims, from the following description, and from the drawings.  
           [0010]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0011]    In the drawing:  
         [0012]    [0012]FIG. 1 shows a perspective view of a structural unit with the lock according to the invention, which is to be attached to a stationary part next to a pivoting flap;  
         [0013]    [0013]FIGS. 2 and 3 show enlarged cross sections through the profiled shaft in the structural unit of FIG. 1 along lines II-II and III-III, respectively, in that figure;  
         [0014]    [0014]FIG. 4 shows an enlarged cross section through the structural unit of FIG. 1 along the line IV-IV in that figure, after the structural unit has been attached to the stationary part and is cooperating with a closing piece attached to a flap, where the flap is in its closed position with respect to the stationary part; and  
         [0015]    [0015]FIG. 5 shows a view of the same area as that of FIG. 4 with the closing piece in its release position.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    The lock according to the invention includes two rotary latches  11 ,  12 , which are supported on two bearing blocks  31 ,  32  at points  13 ,  14 . The bearing blocks  31 ,  32  are integral parts of a carrier  30 . Because the two rotary latches are identical in design, it is sufficient to explain their design and function in greater detail on the basis of the rotary latch according to FIGS. 4 and 5.  
         [0017]    As illustrated in FIG. 4, the lock serves to hold a movable part  15 , which consists in the present case of a pivoting flap, on a resting part  35 . For this purpose, the carrier  30  supporting the two rotary latches  11 ,  12  is attached in the present case to the resting part  35 , for which the attachment points  33 ,  34 , which can be seen at the ends of the carrier in FIG. 1, are used. Two straps, which carry closing pieces  10 , are attached to the pivoting flap  15 , one being assigned to each of the two rotary latches  11 ,  12 . Only one of the straps  16  with its closing piece  10  is shown in FIGS. 4 and 5.  
         [0018]    As shown in FIGS. 4 and 5, each of the rotary latches  11 ,  12  has an opening  17 , which holds the closing piece  10  after the rotary latch  11  has been pivoted into the position indicated by the auxiliary line  11 . 1 , which is to be referred to here as the “closed position”. In this state, the pivoting flap  15  is fastened to its housing  35 . This locking position  11 . 1  is secured by a first locking element  31 , which grips a radial shoulder  18 . The same is also true for the other rotary latch  12 , as shown in FIG. 1, in which a second locking element  22  is supported against a similar radial shoulder  19  provided on that latch  12 .  
         [0019]    The locking elements  21 ,  22  are seated at the ends of a common shaft  20 , which connects the two of them together and with which they form an integral piece of plastic, thus forming a combination with it. This shaft  20  has support pins  23 ,  24  at its ends, as indicated in broken line in FIG. 1, which fit into corresponding blind holes, which face each other. The blind holes belong to two end bearings  36 ,  37 , which are designed as integral parts of the carrier  30 . The rotational axis  25  of the shaft  20  and of its locking elements  21 ,  22  is indicated in dash-dot-line in FIG. 1 and is also marked in FIGS. 4 and 5. Both the rotary latches  11 ,  12  and also the one-piece combination  40  are subject to the action of restoring forces, which in the present case are produced by restoring springs  38 ,  39  with two sidepieces, which act on both components.  
         [0020]    As illustrated in FIG. 4, the restoring spring  38  shown there exerts a force acting in the counterclockwise direction as shown by the force arrow  41 ; this force tries to move the rotary latch out of the closed position  11 . 1  of FIG. 4 into the other rotational position, illustrated by the auxiliary line  11 . 2  in FIG. 5. The rotary latch  11  is prevented from doing this, however, as long as the locking element  21  associated with it is supported against the shoulder  18 . The locking element  21  is itself being acted on by the force of the restoring spring  38 , this force acting in the clockwise direction shown by the force arrow  42  in FIG. 4.  
         [0021]    In the previously mentioned combination  40 , the shaft  20  has a special profile, which makes it torsionally rigid in the rotational direction  43  according to FIGS. 2 and 3, but flexible in the axial direction  25 . This is achieved in that the shaft  20  is produced in such a way that it consists of an alternating sequence of rigid axial sections  26  and flexible axial sections  27 ,  28  as shown in FIG. 1. The rigid axial sections  26  consist of disks with a circular outline  29 , which are positioned in stack-like fashion a certain axial distance apart, the gaps between them being bridged by two diametric webs  44 ,  45 . Successive webs  44 ,  45  are perpendicular to each other. The webs  44 ,  45  act as “film hinges” between the successive disks  26 . Whereas the one web  44 , which extends horizontally, for example, according to FIG. 2, allows bending in the vertical direction, the other, vertical web  45  provides flexibility in the horizontal direction. The extent of this flexibility is determined by the axial dimension of the web between the successive disks  26  and the radial thickness of the web. The torsional rigidity is obtained as a result of the continuity of the web structure and the relatively low height of the webs between adjacent disks  26 .  
         [0022]    The one-piece combination  40  makes it possible to install the shaft  20  quickly and conveniently. Advantage can be taken of its flexibility for this purpose. For the installation process, the shaft  20  is bent until the terminal bearing pins  23 ,  24  of the combination unit  40  just fit between the two end bearings  36 ,  37  of the carrier  30 . Then, by inserting the bearing pins  23 ,  24  into the above-mentioned blind holes, the shaft  20  can be introduced axially into the associated end bearings  36 ,  37 . After the shaft has been fitted into the bearings, a clip  48 , which extends over the installed shaft  20  and is attached to the holders  49  on the carrier, limits the flexure of the central part of the shaft  47 . As a result, a central support point is created, which prevents the shaft from bending so sharply outward again in this area  47 .  
         [0023]    A trigger  50 , on which manually operated actuating means (not shown in detail) act, is present on the combination  40 . Torque is exerted only on the trigger  50 ; there is no need to exert any torque by way of the locking elements  21 ,  22 . When the trigger  50  is moved out of the supporting position in FIG. 4 and into the release position shown in FIG. 5, in which the radial shoulder  18  of the rotary latch  11  is released, the rotary latch  11  pivots automatically into the previously mentioned other position  11 . 2  under the action of the restoring force  41 . This rotational position  11 . 2  is determined by bumpers  51 , which also damp the noise, and against which the rotary latch  11  is supported. These bumpers  51  are a component of the associated bearing block  31  of the carrier  30 . In this rotational position  11 . 2 , the movable part  15 , e.g., a flap, can be pivoted in the direction of the double arrow  52  of FIG. 5. With respect to the support of the flap  15 , the rotary latch  11  assumes a position in which the associated closing piece  15  can be moved into or out of the latch opening  17 . This path of movement  53  is indicated in FIG. 5 in dash-dot line.  
         [0024]    The associated locking element  21  rests under the action of the previously mentioned restoring force against the profile of the rotary latch  11 . For this reason, the outside surface of the latch, which is made of metal, is provided with a sheath  54 , as indicated by the crosshatching in FIG. 5, consisting of an elastomeric material. Preloaded by the restoring spring  38 , the locking element  21  is ready to move from the position shown in FIG. 5 into the position under less tension according to FIG. 4. During the previously mentioned pivoting movement in the closing direction, the closing piece  10  strikes a projection  55 , which forms one boundary of the latch opening  17 , and thus rotates the rotary latch  11  back into the closed position  11 . 1  against the force of its restoring spring  41 . The locking element  21  is able to move automatically behind the latch shoulder  18  again and thus locks the assembly in the closed position  11 . 1 .  
         [0025]    While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.