Abstract:
The invention relates to a fitting for a vehicle seat, in particular a motor vehicle seat, comprising a first fitting part; a second fitting part which can be rotated about an axis in relation to the first fitting part; an eccentric which is rotationally mounted about the axis and which can be driven; at least two locking devices, which are guided in a radial direction by the first fitting part, can be displaced in a radial direction in an outward manner by the eccentric and which co-operate in a radial manner towards the outside with the second fitting part in order to lock the fitting; and at least one spring arrangement ( 17 ) which impinges upon the eccentric. The spring arrangement ( 17 ) comprises two springs ( 27, 28 ) which are arranged in a central manner and are placed within each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application is a continuation of International Application PCT/EP2006/007072, which was filed Jul. 19, 2006. The entire disclosure of International Application PCT/EP2006/007072, which was filed Jul. 19, 2006, is incorporated herein by reference. 

   TECHNICAL FIELD 
   The present invention relates to a fitting for a vehicle seat, in particular a motor vehicle seat, with the fitting having a first fitting part; a second fitting part that can be rotated about an axis relative to the first fitting part; a drivable eccentric that is mounted for rotating about the axis; at least two locking elements that are guided in the radial direction with respect to the axis by the first fitting part, can be moved radially outward under the action of the eccentric, and interact radially outward with the second fitting part in order to lock the fitting; and at least one spring arrangement for acting upon the eccentric. 
   BACKGROUND OF THE INVENTION 
   DE 102 53 054 A1 (which is a member of the same patent family as U.S. Pat. No. 6,991,295) discloses a fitting of the type described in the above Technical Field section of this disclosure. DE 102 53 054 A1 discloses a fitting in which the eccentric is acted upon symmetrically and hence in a manner free from transverse force by two radially opposite spring arrangements, in order for the eccentric to act upon the two locking elements when locking the fitting. The spring arrangements are offset with respect to the axis of the fitting by 90° with respect to the locking elements. The spring arrangements and the locking elements are in the same plane. 
   BRIEF SUMMARY OF SOME ASPECTS OF THE INVENTION 
   One aspect of the present invention is the provision of improvements to a fitting of the type mentioned above. In accordance with one aspect of the present invention, a fitting for a vehicle seat, in particular a motor vehicle seat, includes first and second fitting parts mounted so that there can be relative rotation, about an axis, between the first and second fitting parts; an eccentric mounted for being rotated about the axis; at least two locking elements that are guided by the first fitting part for moving radially outward, with respect to the axis, in response to rotation of the eccentric, so that the locking elements interact with the second fitting part in order to lock the fitting while the locking elements are positioned radially outwardly; and at least one spring arrangement for acting upon the eccentric, wherein the spring arrangement includes springs, and the springs are centrally arranged and nested one inside the other. 
   Because the (e.g., single) spring arrangement has two springs which are centrally arranged and nested one inside the other, firstly, because of the nested arrangement, a symmetrical action of the spring arrangement on the eccentric can be achieved, which action is without transverse forces. This action, which is free from transverse force, on the eccentric prevents the eccentric from being laterally displaced out of its predetermined position by transverse forces and therefore carrying out its task less well. Secondly, the central arrangement means that the construction space between the locking elements is available for other components, for example for further locking elements. With this increased number of locking elements, the fitting can be designed as a high-load fitting and can be used for belt-integral seats, which increases the versatility of the fitting. 
   In order to take up as little construction space as possible, the spring arrangement is preferably arranged in a central cutout of the first fitting part, with it being possible for the cutout (e.g., opening) to be a continuous opening or a depression which is closed on one side. In order to provide sufficient space for the eccentric, the spring arrangement is preferably arranged in a plane offset axially with respect to the eccentric, which can be achieved in a simple manner by a planar design of the first fitting part in the region of the cutout. 
   The two springs are preferably arranged around the axis and are preferably offset with respect to the axis by 180° with respect to each other, which in each case structurally simplifies the symmetrical action upon the eccentric. In the preferred spiral design of the two springs, which saves construction space, each spring has an outer and an inner spring end. The two springs are supported on the first fitting part preferably by their outer spring ends, which, in particular in the case of the first fitting part having the cutout, can easily be realized by radial grooves or the like. Correspondingly, the two springs act upon the eccentric preferably with their inner spring ends. In the case of the preferred arrangement in a plane offset axially with respect to the eccentric, the inner spring ends can be designed as axially protruding end fingers which engage in the eccentric, or, conversely, the eccentric can have axially protruding projections which are engaged around by the inner spring ends, which are then preferably designed as hooks. 
   The fitting according to the invention is preferably used in a vehicle seat to attach the backrest to the seat part and to set the inclination of the backrest, but it could also be used in some other way in a vehicle seat. 
   Other aspects and advantages of the present invention will become apparent from the following. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
     The invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawings, together with a modification that is also illustrated in the drawings. In the drawings: 
       FIG. 1  shows an exploded illustration of the exemplary embodiment, 
       FIG. 2  shows a schematic illustration of a vehicle seat, 
       FIG. 3  shows a slightly perspectively illustrated section through the exemplary embodiment in a plane between the locking elements and the control disk, 
       FIG. 4  shows a perspective view of the spring arrangement of the exemplary embodiment, 
       FIG. 5  shows a perspective view of the spring arrangement of the modification, and 
       FIG. 6  shows a perspective view of the eccentric of the modification. 
   

   DETAILED DESCRIPTION  
   A vehicle seat  1  of a motor vehicle has a seat part  3  and a backrest  4 . The backrest  4  is laterally attached to the seat part  3  by way of two fittings, so that the backrest  4  can be pivoted (e.g., inclined) relative to the seat part  3  and can be locked at different settings of the inclination. The orientation of the vehicle seat  1  in the motor vehicle and its customary direction of travel define the directional details used in this detailed description. The vehicle seat  1  is designed as a seat with an integral seat belt (i.e. the upper end of a seatbelt is fastened to the backrest  4 , more specifically to an automatic belt device on the upper edge of the backrest  4 ). The forces introduced into the backrest  4  via the seatbelt in the event of loading can therefore be conducted on into the seat part  3  via the fittings, which is why at least the fitting  5  on the side of the vehicle seat which is subjected to a higher load and to which the seatbelt is attached is designed as a high-load fitting. 
   The fitting  5  is based on the same general principle as the fitting described in DE 102 53 054 A1 (which is a member of the same patent family as U.S. Pat. No. 6,991,295), the entire disclosure of which is expressly incorporated herein by reference. The fitting  5  is designed as a latching fitting in disk form. The fitting  5  has a first fitting part  7  and a second fitting part  8  which can be rotated about an axis A relative to the first fitting part  7 . The fitting parts  7  and  8  define a construction space that is between the fitting parts  7  and  8 . A clasping ring  9  annularly reaches over and engages the second fitting part  8  and is connected to the first fitting part  7 , as a result of which the two fitting parts  7  and  8  are held together axially. In the exemplary embodiment, the first fitting part  7  is connected to the seat part  3 , and the second fitting part  8  is connected to the backrest  4 . However, the converse arrangement is also possible. 
   A driver  10  is arranged in the center of the fitting  5 . The driver  10  is mounted on the second fitting part  8  in a manner such that the driver  10  is rotatable about the axis A that is arranged in the center of the fitting  5 . An eccentric  11  that is arranged in the construction space is seated in a rotationally fixed manner on the driver  10 , or the eccentric  11  is at least coupled to the driver  10  for being carried along by the driver. The eccentric  11  acts on four identical locking elements  13  that are arranged in the construction space around the eccentric  11 . The locking elements  13  are offset by 90° with respect to one another. Each of the locking elements  13  is provided, on its radially outer side (with respect to the axis A), with a toothing in order to interact with a toothed ring  14  of the second fitting part  8 , which is designed as an internal gearwheel. The locking elements  13  are guided in the radial direction by guide segments  15  of the first fitting part  7 . The toothed ring  14  of the second fitting part  8  rests upon the four guide segments  15 , as a result of which the second fitting part  8  is mounted on the first fitting part  7 . 
   A spring arrangement  17  (described more specifically below) is arranged in a central opening (e.g., cutout) of the first fitting part  7  and acts upon the eccentric  11  such that the eccentric  11  presses the locking elements  13  radially outward, i.e. into the toothed ring  14 ; therefore, the fitting  5  is locked. A control disk  19  is arranged in the construction space axially between the locking elements  13  and the second fitting part  8 . In the exemplary embodiment, the control disk  19  is seated in a rotationally fixed manner on the eccentric  11 . The control disk  19  has four slotted guides  19 ′, each of which interacts with a lug  13 ′ of a respective one of the locking elements  13 . The lugs  13 ′ protrude in the axial direction from the locking elements  13 . When the driver  10 —and therefore the eccentric  11  and the control disk  19  driven thereby—is rotated counter to the force of the spring arrangement  17 , the control disk  19  pulls the locking elements  13  radially inward, i.e. out of engagement with the toothed ring  14 , and therefore the fitting  5  is unlocked. 
   The driver  10  is mounted in an opening of the second fitting part  8 , with the driver  10  being mounted by way of a hub. Two integrally formed ribs  10 ′ of the driver  10  bear in the axial direction against the inside of the second fitting part  8 . A securing ring  20 , which is arranged on the outside of the second fitting part  8 , is fixedly seated on the hub of the driver  10 . The securing ring  20  is clipped onto the hub of the driver  10  during assembly of the fitting  5 , so that the driver  10  is axially secured. 
   During proper use, i.e. normally, a play necessary for the operation of the fitting  5  could lead to noise being generated. Therefore, provisions are made so that, when the fitting  5  is locked, the locking elements  13  can tilt—laterally with respect to the radial direction—even in the normal situation in order to compensate for the play (in particular in the circumferential direction). For this purpose, first eccentric cams  21  and second eccentric cams  22  are formed on the eccentric  11 . The first eccentric cams  21  protrude radially somewhat over (e.g., radially farther outward than) the second eccentric cams  22 . The four first eccentric cams  21  and the four second eccentric cams  22  form four pairs. As viewed in the circumferential direction of the eccentric  11 , the sequence of the cams  21 ,  22  within a pair changes from pair to pair, i.e. two mutually adjacent first eccentric cams  21  are followed by two mutually adjacent second eccentric cams  22 , and vice versa. Each pair is assigned precisely one locking element  13 . Two locking cams  23 —preferably of identical design—are arranged on each locking element  13 , on the side facing the eccentric  11  and offset with respect to the radial center line of the locking element  13 . For each of the locking elements  13 , one of the locking cams  23  is aligned with a first eccentric cam  21 , and the other locking cam  23  is assigned to a second eccentric cam  22 . 
   When the eccentric  11  acts upon the locking elements  13 , this normally means that only the first eccentric cam  21  in each case acts upon the locking cam  23  assigned to it, and therefore the locking element  13  moves radially outward while there is a gap between the second eccentric cam  22  in each case and the locking cam  23  assigned to it. As soon as the locking element  13  engages in the toothed ring  14 , the locking element  13  tilts, i.e. rotates somewhat, in a direction indicated by a curved arrow in  FIG. 3 , until the play is compensated for. The locking element  13  then acts as a diagonal strut and is in contact at three points P with in each case one other component of the fitting  5 , namely with the assigned first eccentric cam  21 , i.e. the eccentric  11 , the nearest adjacent guide segment  15 , i.e. the first fitting part  7 , and the toothed ring  14 , i.e. the second fitting part  8 . Because of the alternating sequence in the pairs of eccentric cams  21  and  22 , the locking elements  13  tilt in an alternating direction, i.e. in each case in opposite directions to their respective neighbors. In each case, two mutually opposite locking elements  13  therefore tilt in the same direction which is in the opposite direction to that of the other two locking elements  13 . 
   If a force is now exerted on the backrest  4 , for example via the seatbelt, and in particular in the event of a crash, the second fitting part  8  experiences a torque. As a result, the second fitting part  8  exerts, by way of the toothed ring  14 , a force in the circumferential direction on the four locking elements  13 . For two locking elements  13 , this force, i.e. load, acts in the direction in which they are tilted, and they therefore, firstly, can immediately conduct the force on and, secondly—if appropriate under elastic and/or plastic deformation—tilt somewhat further until the respective locking cam  23 , which has been free up to now, comes into contact with the second eccentric cam  22 , i.e. there is no longer a gap. However, the small movement of the locking elements  13  leads to slightly reduced strength. Upon a further increase in force, the force is now essentially conducted onto the eccentric  11  via the locking cam  23  which was free up to now. For the two other locking elements  13 , the force, i.e. load, acts counter to the direction in which they are tilted. These two locking elements  13  therefore tilt counter to the original tilting direction and, in the process, conduct the force directly into the eccentric  11  via the respective first eccentric cam  21 . In this case, these two locking elements  13  oppose the load with increased strength. 
   Because of the tilting normally of the locking elements  13  in the opposite direction, the same situation arises for a head-on crash and rear crash, i.e. the force flux passes in each case through a pair of locking elements  13  with two supported locking cams  23  (and, in the process, primarily via the previously free locking cam  23 ) and through a pair of locking elements, in which (furthermore) only one locking cam  23  is supported. The strength therefore significantly increases in total over an arrangement with just two locking elements, but also over an arrangement in which all of the locking elements tilt in the same direction, and therefore a loading direction would be opposed by lower strength. 
   For construction-space reasons, the spring arrangement  17  is arranged centrally in the first fitting part  7 . If the spring arrangement  17  were to act on the eccentric  11  on one side, transverse forces would arise which would bring the eccentric  11  from its centered position into an asymmetrical position, which would cause a deterioration in its operation. In order to avoid this, the spring arrangement  17  comprises a first spring  27  and a second spring  28  which are each designed per se as a flat spiral spring. The two springs  27  and  28  are arranged rotated (e.g., rotationally offset) with respect to each other by 180° around the axis A and are nested one inside the other, i.e. the distances between the respective coils are selected to be of a size sufficient that a coil of the second spring  28  comes to lie between two coils of the first spring  27 , and a coil of the first spring  28  comes to lie between two coils of the second spring  28 , and there is also sufficient spring deflection in each case for contraction or expansion. 
   The two springs  27  and  28  are supported on the first fitting part  7  by way of their outer spring ends. The outer spring ends of the springs  27 ,  28  are angled radially and engage in a form-fitting manner in corresponding radial grooves of the central opening of the first fitting part  7 . The radial grooves of the central opening of the first fitting part  7  are positioned radially opposite from one another. The action upon the eccentric  11  by the springs  27  and  28  takes place by way of the respective inner spring ends. In accordance with the exemplary embodiment, the inner spring ends are referred to, for the first spring  27 , as first end finger  27   a , and, for the second spring  28 , as second end finger  28   a . The two end fingers  27   a  and  28   a  are angled axially, since the eccentric  11  is arranged in an axially offset plane from the coils of the springs  27 ,  28 . Also, the two end fingers  27   a  and  28   a  are arranged radially opposite each other. The end fingers  27   a  and  28   a  engage in correspondingly shaped, lateral cutouts of a central opening of the eccentric  11 . The central opening of the eccentric  11  receives the driver  10 , and the end fingers  27   a  and  28   a  end between the driver  10  and the eccentric  11 . The symmetrical arrangement, supporting and acting upon the two springs  27  and  28  causes the transverse forces to be eliminated, and therefore the eccentric  11  as a whole is acted upon in a manner free from transverse force. 
   In a modification of the exemplary embodiment, a spring arrangement  117  has a first spring  127  and a second spring  128  which are likewise (i.e., in the same manner discussed above) nested one inside the other, but, instead of having end fingers, the first and second springs  127 ,  128  respectively have a first hook  127   b  and a second hook  128   b , which are each curved radially inward. For action upon the eccentric  111 , axially protruding fingers  111   b  are provided on the eccentric  111 , and the two hooks  127   b  and  128   b  respectively engage around the fingers  111   b . In all other features, the modification corresponds to the exemplary embodiment. 
   The springs  17  and  18  or  117  and  118  are also to be considered to be nested one inside the other if merely projections (of the springs) overlap one another in a plane that extends perpendicularly with respect to the axial direction, while the springs are arranged axially offset with respect to one another. 
   It will be understood by those skilled in the art that while the present invention has been discussed above primarily with reference to an exemplary embodiment, various additions, modifications and changes can be made thereto without departing from the spirit and scope of the invention as set forth in the claims.