Abstract:
A locking device and a headrest are disclosed. The locking device includes spring elements, which can be engaged in at least one locking position and the locking device can be displaced in relation to at least two retaining bars that have a large number of recesses. The spring elements co-operate with the recesses in such a way that the engagement of the spring elements in their locking position locks the locking device in relation to the retaining bars. According to the invention, the spring elements are configured in such as way that the retaining bars are locked by the mechanical fixing of the spring elements in their central zone or by exertion of a force on the spring elements in their central zone.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present Application claims the benefit of priority to the following International Application: PCT Patent Application No. PCT/EP2004/002701 titled “Locking Device and Headrest” and filed on Mar. 16, 2004, which claims priority to German Patent Application No. DE10312517.5 titled “Locking Device and Headrest” and filed on Mar. 20, 2003 (which are both incorporated by reference in their entirety). 
     
    
     FIELD  
       [0002]     The invention relates to a locking device. For motor vehicles, in particular, headrests are used which provide a user of the vehicle with increased comfort and increased security against possible sources of risks, for example in the case of accidents, by supporting or retaining body parts, in particular of the head.  
       BACKGROUND  
       [0003]     Headrests of this type are generally provided in a manner such that they can be set, for example, to users of different heights. In order to set the headrests, the latter can be locked mechanically in a plurality of positions. The setting of the headrests is accomplished easily, simply and with little effort. At the same time, however, once a headrest is set and locked, resistance to forces which may potentially move the headrest out of the set position is desired. Headrests of this type and the individual parts of which they are composed are furthermore to be able to be produced and assembled simply and cost-effectively, with the result that the production of headrests of this type can be carried out simply, rapidly and cost-effectively.  
         [0004]     For example, European patent specification EP 0 864 461 B1 discloses a headrest for motor vehicle seats with a rapid height adjustment. In this case, two wire springs are provided which can be bent by at least one actuating rod, so that the locking brought about by the two wire springs in their normal position is canceled. However, in the case of such a construction of a headrest, it is disadvantageously envisaged using two separate springs. Furthermore, special C-shaped springs are used which can only be fitted in a comparatively time-consuming manner, in a comparatively complicated manner and with a comparatively large exertion of force. Furthermore, the two springs used have a different locking effect, for example due to manufacturing fluctuations. On account of the use of two separate springs and two separate retaining rods, this has the effect of the support being possibly able to be positioned in different adjusting positions, i.e., for example, “obliquely”, on the different retaining rods, which may result in disadvantageous consequences, in particular with regard to protecting occupants in motor vehicles in hazardous situations.  
       SUMMARY  
       [0005]     The invention therefore provides a locking device in which the disadvantages of the locking devices known from the prior art are avoided.  
         [0006]     Accordingly the locking device is provided in a manner such that it can be adjusted relative to at least two retaining rods, the locking device having spring elements which are provided in a manner such that they can be set at least into one locking position, the spring elements in their locking position, in interaction with recesses in the retaining rods, causing the locking device to be locked relative to the retaining rods, the spring elements being provided in such a manner that locking of the retaining rods can be brought about by a mechanical fixing of the spring elements in a central region or the locking of the retaining rods can be brought about by an application of force on the spring elements in a central region. In one embodiment of the locking device, the spring elements are provided as a single part. In a further embodiment of the locking device, the spring elements are provided as a spring extending in an elongate manner essentially between the two retaining rods. In a further embodiment of the locking device, the spring elements are provided in such a manner that they comprise at least one central part and end parts. Such locking devices have the advantage that the spring elements have a uniform locking effect on both retaining rods, since the locking effect for the alternative of exerting a force on the spring elements in the central region—in contrast to merely fixing the spring elements without a noticeable application of force on the spring elements—is brought about by a single elastic deformation of the spring, in particular in the central region of the spring elements.  
         [0007]     In a another embodiment of the locking device, the spring elements, in addition to their locking position, are provided in a manner such that they can be set into a release position, the spring elements interacting with the recesses of the retaining rods in such a manner that, when the spring elements are set in their release position, the recesses are opened up. In a further embodiment of the locking device, the latter has a sliding element which can be set at least in a first position and in a second position, the spring elements interacting with the sliding element in such a manner that, when the sliding element is set into its first position, the spring elements take up their locking position and that, when the sliding element is set into its second position, the spring elements take up their release position. In a further embodiment of the locking device, the sliding element has a plurality of projections and the spring elements have a plurality of actuating regions, a movement of the sliding element parallel to a plane defined by the at least two retaining rods bringing about a movement of the actuating regions which is essentially vertical thereto. In a further embodiment of the locking device, the spring elements are elastically deformed by the movement of the actuating regions. In a further embodiment of the locking device, the actuating regions are of wedge-like design. In a further embodiment of the locking device, the locking device has a bearing point, the bearing point preventing a movement of the central region of the spring elements during the movement of the actuating regions. Such locking devices have the advantage of being able to be produced and fitted in a very simple and sturdy manner.  
         [0008]     A further subject matter of the present invention is a headrest which is used, in particular, in a motor vehicle. The headrest is connected fixedly to a locking device. In particular, the design of the headrest is such that the locking device cannot be seen from outside the headrest or at most partially, for example through an actuating device. In this case, the headrest has a frame which has guide elements for retaining rods or is connected thereto. The retaining rods protrude in particular out of the upper boundary surface of a backrest of a seat of a motor vehicle, so that by setting of the backrest in a manner such that it is generally essentially vertical or is inclined slightly in relation to the vertical, the retaining rods are essentially vertical or likewise slightly inclined in relation to the vertical. Accordingly, the headrest is therefore height-adjustable with the retaining rods extending essentially vertically. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0009]     The invention is explained in more detail below with reference to an exemplary embodiment which is illustrated in the drawing, in which  
         [0010]      FIG. 1  shows a headrest with retaining rods and an indicated locking device according to the invention.  
         [0011]      FIG. 2  shows part of a headrest with the locking device indicated.  
         [0012]      FIG. 3  shows an exploded drawing of individual parts of the headrest and in particular of the locking device.  
         [0013]      FIG. 4  shows a plan view in the direction of the retaining rods of the locking device, with the spring being situated in its locking position.  
         [0014]      FIG. 5  shows a plan view in the direction of the retaining rods of the locking device, with the spring being situated in its release position. 
     
    
     DETAILED DESCRIPTION  
       [0015]      FIG. 1  illustrates a headrest  10  with retaining rods  20  and an indicated locking device. The retaining rods  20  here are fastened by their lower part  21  in particular in a backrest (not illustrated) of a seat of a motor vehicle. The headrest  10  has a comparatively soft material which is denoted by the reference number  11 , which makes up the major part of the volume of the headrest  10  and serves for supporting and stabilizing the head of a user of the headrest.  
         [0016]      FIG. 2  illustrates part of a headrest  10  with the locking device. In this case, the headrest  10  comprises a frame  15  which gives the headrest an inherent mechanical support.  FIG. 2  furthermore illustrates the retaining rods  20 , their recesses  22  and their lower parts  21 . Recesses  22  are provided in particular as notches  22 . Furthermore,  FIG. 2  illustrates the spring elements  30 . The spring elements  30  are provided as a spring  30  extending in an elongate manner between the retaining rods  20 . In one embodiment of the invention, the spring  30  is provided as a single part formed of spring wire. In another embodiment of the invention, the spring  30  is provided in a central section, which is formed by a central part, as a plastic part and is provided in its end sections as a metal end part or as a plurality of metal end parts.  
         [0017]      FIG. 3  illustrates an exploded drawing of individual parts of the headrest  10  and in particular of the locking device. The headrest  10  comprises the frame  15  and guides  17  in which the retaining rods  20  are guided. The locking device has a support part  50  which bears the components required for locking the locking device relative to the retaining rods  20 , and is at least partially mechanically fixed. The support part  50  is connected in particular to the guides  17  and is provided as a single part with them, for example as a plastic or metal injection-molded part. The spring  30  and a sliding element  40  are placed onto or into the support part  50 , with both the spring  30  and the sliding element  40  being provided in a manner such that they can be moved mechanically within limits in or on the support part  50 . The support part  50  has—connected as a single part in  FIG. 3 —a receptacle  54  for an actuating device  70 . However, a receptacle (not illustrated) which is not provided as a single part with the support part  50  is likewise possible. The actuating device  70  includes an actuating guide  60 , a restoring spring  62  and an actuating button  64 . The actuating button  64  is connected mechanically to the sliding element  40  by a latching connection, and is accessible to a user (not illustrated in  FIG. 3 ) of the locking device from outside the headrest  10 . However, a different design of the actuating device  70  and a different connection of the sliding element  40  to a component of the actuating device  70  that is accessible to the user of the locking device is likewise possible.  
         [0018]      FIG. 4  illustrates a plan view of the locking device in the direction of the retaining rods  20 , with the spring  30  being situated in its locking position, and  FIG. 5  illustrates a plan view of the locking device in the direction of the retaining rods  20 , with the spring  30  being situated in its release position. The locking position of the spring  30  is characterized in that locking regions  31  of the spring  30  bear against the retaining rods  20 . In this case, the sliding element  40  is set in a first position. This position is brought about in particular by the spring action of the restoring spring  62  (not illustrated in  FIGS. 4 and 5 ) of the actuating device  70  on the actuating button  64  and therefore on the sliding element  40 . The sliding element  40  has projections  42 ,  43  which can lead to a movement of the spring  30  during a movement of the sliding element  40 . The first position of the sliding element  40 , illustrated in  FIG. 4 , is characterized in that the projections  42 ,  43  bear against the spring  30  but do not exert a force on the spring. The exertion of such a force would impair the locking effect of the spring  30  on the retaining rods  20 . In the exemplary embodiment illustrated, the locking regions  31  are provided in particular at the two ends of the spring  30  extending in an elongate manner. The locking of the retaining rods  20  relative to the locking device or relative to the headrest  10  is brought about by the locking regions  31  of the spring  30  engaging the recesses  22  (not illustrated in  FIGS. 4 and 5 ) of the retaining rods  20 . In this case, the spring  30  is already “prestressed” in its locking position and an application of force of the spring  30  on the retaining rods  20  is therefore provided. This application of force of the spring  30  is brought about by a bearing point  52  which is provided on the support part  50 . In this connection, the support part  50 , by means of the bearing point  52 , exerts an application of force on the spring  30 , in a central region  35  of the spring  30 . This causes an elastic bending of the spring  30  in its central region  35 , and therefore an exertion of force on both retaining rods  20  or on their recesses  22 . The central region  35  of the spring  30  is provided approximately in the center between the retaining rods  20 , but this is not necessarily the case.  
         [0019]     In another embodiment, the spring  30  bears merely against the two retaining rods  20  and the bearing point  52 . By the mechanical fixing of the spring  30  on the bearing point  52 —in the central region  35 —locking of the locking device relative to the retaining rods  20  is already provided. It is clear that, in the case of locking without application of force in the locking position of the spring  30 , the ability to fit the spring  30  is facilitated.  
         [0020]     The release position (illustrated in  FIG. 5 ) of the spring  30  is characterized in that the locking regions  31  of the spring  30  release the retaining rods  20  and therefore open up the recesses  22 , i.e. the locking regions  31  of the spring  30  are provided at a distance from the retaining rods  20 . As a result, it is possible for the retaining rods  20  to be easily displaceable in their longitudinal direction, i.e. perpendicular with respect to the plane of the drawing in  FIGS. 4 and 5 , in relation to the locking device. The release position of the spring  30  is brought about, starting from its locking position, by the sliding element  40  being brought into its second position illustrated in  FIG. 5 . In this case, the sliding element  40  is displaced to the left, starting from its position in  FIG. 4 , relative to the support part  50 , and the projections  42 ,  43  on the sliding element  40  together with wedge-like actuating regions  32 ,  33  of the spring  30  bring about a movement of the spring  30  into its release position. In this case, the locking regions  31  of the spring  30  move in a direction perpendicular with respect to the direction of movement of the sliding element  40 . The movement of the sliding element  40  takes place here in a plane parallel to the plane which is perpendicular to the plane of the drawing in  FIG. 5  and is defined by the two retaining rods  20 .  
         [0021]     In an alternative embodiment, in which the spring  30  is provided in a central section, which is formed by a central part, as a plastic part and with the spring being provided in its end sections as a metal end part or as a plurality of metal end parts, the embodiment contemplates that the end parts form the locking regions  31  and the central part forms the remaining sections of the spring  30 , in particular the actuating regions  32 ,  33 .