Abstract:
A fitting for a vehicle seat has a first fitting part and a second fitting part that relatively rotate about an axis. A toothed rim ( 17 ) is on the first fitting part and guide segments ( 14 ) are on the second fitting part. Bars ( 16 ) are guided by the guide segments between an unlocked state and a locked state, interacting with the toothed rim. A spring-loaded, rotatably mounted eccentric ( 27 ) urges the bars to interact with the toothed rim. A rotatable driver ( 21 ) rotates the eccentric. A fastening ring ( 24 ) is connected to the driver. A cam ( 24   n ) is formed on the fastening ring and bears in the circumferential direction against a driver cam ( 21  f) of the driver. The fastening ring has a collar ( 24   b ) with a passage ( 24   d ) about the axis. The cam is formed within the passage such that it is oriented in the radial direction towards the axis.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase Application of International Application PCT/EP2013/062959 filed Jun. 21, 2013 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2012 012 847.9 filed Jun. 26, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a fitting for a vehicle seat, in particular for a motor vehicle seat, having a first fitting part and a second fitting part which can be rotated about an axis relative to one another, wherein a toothed rim is formed on the first fitting part and guide segments are formed on the second fitting part, and locking bars are displaceably guided between a locked state and an unlocked state by the guide segments and which cooperate with the toothed rim in the locked state in order to lock the fitting, a spring-loaded, rotatably mounted eccentric which acts on the locking bars in order to bring them into cooperation with the toothed rim, a rotatably mounted driver for rotating the eccentric, a fastening ring connected fixedly to the driver and a cam formed on the fastening ring and bears in the circumferential direction against at least one driver cam of the driver. 
     BACKGROUND OF THE INVENTION 
     A generic fitting is disclosed in DE 10 2008 024 853 A1, the fastening ring thereof having three axially aligned projections which engage in three axial recesses of a driver and thus determine the angular position of the fastening ring relative to the driver. One respective edge formed on the projections in the circumferential direction bears in this case against a surface of the driver and is ultrasonically welded in this region. It is a drawback that a circumferential ultrasonic welded connection is not produced, as it is only possible to carry out the welding in the region of the projections. Additionally, as the relevant components are simultaneously pushed together axially, weld deposit is produced during the ultrasonic welding, said weld deposit not being able to be completely removed from the recesses. 
     DE 20 2011 106 338 U1 also discloses a fitting having a fastening ring. The fastening ring, however, does not have any means which produce a defined angular position of the fastening ring relative to the driver. 
     A complex lever mechanism for unlocking a fitting is disclosed in U.S. Pat. No. 7,100,987 B2. A crank drive of the lever mechanism drives a driver of the fitting. A separately configured fastening ring connected to the driver is not a component of the fitting. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to improve a fitting of the type mentioned in the introduction, in particular to ensure by simple means the angular position of the fastening ring relative to the driver and to provide the possibility of an optional, circumferential ultrasonically welded seam between the fastening ring and the driver and by using such a fitting to provide a vehicle seat which is cost-effective and has a high degree of strength and low tolerances. 
     According to the invention, a fitting is provided for a vehicle seat, in particular for a motor vehicle seat, comprising a first fitting part and a second fitting part which can be rotated about an axis relative to one another, wherein a toothed rim is formed on the first fitting part and guide segments are formed on the second fitting part. Locking bars are displaceably guided between a locked state and an unlocked state by the guide segments and cooperate with the toothed rim in the locked state in order to lock the fitting. A spring-loaded, rotatably mounted eccentric acts on the locking bars in order to bring the locking bars into cooperation with the toothed rim. A rotatably mounted driver is provided for rotating the eccentric. A fastening ring is configured separately from the driver and is connected fixedly to the driver. At least one first cam is formed on the fastening ring and bears in the circumferential direction against at least one driver cam of the driver. The fastening ring has a collar with a passage about the axis and the at least one first cam is formed within the passage such that it is oriented in the radial direction toward the axis. 
     According to another aspect of the invention, a vehicle seat in particular a motor vehicle seat is provided having at least one fitting according to the invention. 
     As the fastening ring has a collar with a passage about the central axis and at least one first cam is formed inside the passage in the radial direction aligned with the central axis, a simple angular centering may be provided during the mounting process, in particular when pushing the fastening ring onto the driver. Additionally, there is the possibility of producing a circumferential ultrasonically welded seam between the fastening ring and the driver. 
     For particularly effective angular centering during the pushing-on process, at least one driver cam protrudes in the axial direction from a front face of the driver and cooperates with the at least one first cam of the fastening ring. To this end, the at least one driver cam has a centering surface which in the circumferential direction bears against a bearing surface of the at least one first cam of the fastening ring. In this case, a centering angle of 6°+/−4°, preferably of 4°+/−1°, is provided between the centering surface and the bearing surface, at least in regions. A slight relative angular deviation about the central axis which is potentially present may be compensated by means of this centering angle, by the bearing surfaces of the first cam inclined about the centering angle when pushed on in the axial direction sliding on the centering surfaces of the driver cams and, as a result, the fastening ring being rotated into the correct angular position. 
     Preferably, the bearing surface of the at least one first cam of the fastening ring is inclined in the axial direction relative to a line parallel to the axis in a first partial portion and is configured to extend parallel to the axis in a second partial portion. The centering angle is thus only present in the first partial portion. The centering surface and the bearing surface of the fully mounted fitting only bear against one another in the second partial portion without the centering angle. As a result, in the fully mounted state, an axial force component which could move the fastening ring away from the driver does not act on the fastening ring. 
     A centering of the fastening ring in the radial direction when the fastening ring is first pushed onto the driver may be improved by the driver cam at its end remote from the front face of the driver having a circumferential chamfer on its internal edge. 
     As at least two cam pairs are provided, consisting in each case of one of the driver cams and one of the first cams, said cam pairs bearing against one another in the respective opposing circumferential direction, preferably by the at least two cam pairs being configured mirror-symmetrically relative to one another, the angular centering acts in both circumferential directions. 
     The fastening ring in the radial direction may be aligned particularly effectively relative to the driver, by the fastening ring preferably having three or more second cams which bear against the driver in the radial direction. Three second cams provide a statically defined support according to the principle of a tripod. A doubling of the number of second cams to six second cams, which are preferably distributed evenly over the circumference, provides an optimal alignment even in the event of changing load directions. 
     Ultrasonic welding is a preferred joining method for connecting the fastening ring to the driver, as it is cost-effective and yet has high strength. Particularly good welding results may be achieved by an edge of the fastening ring circulating around the central axis bearing against an annular surface of the driver circulating around the central axis, and being welded in said bearing region. The weld deposit produced during the ultrasonic welding process may be advantageously collected as a gap is present between the fastening ring and the driver adjacent to the at least one second cam, said gap being able to be filled with the weld deposit. 
     The invention is described in more detail hereinafter with reference to an advantageous exemplary embodiment shown in the figures. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic view of a vehicle seat; 
         FIG. 2  is a perspective view of a fitting; 
         FIG. 3  is an exploded view of the fitting; 
         FIG. 4  is an axial section through the fitting; 
         FIG. 5  is an exploded view of the driver and fastening ring; 
         FIG. 6  is a perspective view of the fastening ring; 
         FIG. 7  is a plan view of the driver and the fastening ring; 
         FIG. 8  is a sectional view along the line VIII-VIII in  FIG. 7 ; 
         FIG. 9   a  is a perspective view of the fastening ring when first pushed onto the driver; 
         FIG. 9   b  is a perspective view of the fastening ring during the process of being pushed onto the driver; and 
         FIG. 9   c  is a perspective view of the fastening ring fully mounted on the driver. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular, vehicle seat  1  for a motor vehicle has a seat part  3  and a backrest  4  which is attached to the seat part  3  in a pivotable manner relative to the seat part  3  by means of one respective fitting  10  on both sides of the vehicle seat  1 . 
     The fitting  10  has a first fitting part  11  and a second fitting part  12  which can be rotated about an imaginary central axis A relative to one another. The axis A is arranged horizontally in the transition region between the seat part  3  and the backrest  4  and defines the directional information of a cylinder coordinate system used. The two fitting parts  11  and  12  may in each case approximately describe a circular disk shape. Both fitting parts  11  and  12  preferably consist of metal, in particular steel, which may be at least partially hardened. For receiving the axially acting forces, i.e. for axially holding together the fitting parts  11  and  12 , a clasping ring  13  is provided. The clasping ring  13  preferably consists of metal, in particular steel, which is preferably unhardened. The clasping ring  13  preferably has a substantially planar annular shape but in an alternative embodiment may be profiled in an L-shape with a cylinder portion and on the front face a planar annular portion. 
     The clasping ring  13  is fixedly connected to one of the two fitting parts  11  and  12 , in the present case in an outer annular portion to the second fitting part  12 , for example by means of laser welding or by means of a further fastening technique known per se. By means of an internal annular portion, which is arranged in a plane perpendicular to the axial direction, optionally by the interposition of a sliding ring, the clasping ring  13  encompasses the first fitting part  11  in the radial external edge region thereof, without hindering the relative movement of the two fitting parts  11  and  12 . Additionally, the internal surfaces of the two fitting parts  11  and  12  facing one another are protected from the penetration of foreign bodies and soiling and damage. 
     The clasping ring  13  and the fitting part  12  connected fixedly thereto thus clasp the fitting part  11  which is movable relative thereto. In terms of construction, therefore, the two fitting parts  11  and  12  form together (with the clasping ring  13 ) a disk-shaped unit. 
     When mounting the fitting  10 , the first fitting part  11  is connected, for example, to the backrest  4 . The second fitting part  12  is then fixedly connected to the structure of the seat part  3 , i.e. fixed to the seat part. In the present case, the second fitting part  12  is welded to a seat part adapter by means of laser welding. However, the assignments of the fitting parts  11  and  12  may also be reversed, i.e. the first fitting part  11  could then be connected fixedly to the seat part and the second fitting part  12  to the backrest  4 . The fitting  10  is located in the flux of force between the backrest  4  and the seat part  3 . 
     The fitting  10  is configured as a latching fitting in which the first fitting part  11  and the second fitting part  12  may be locked together, as described for example in DE 10 2006 015 560 B3. 
     The second fitting part  12  has—in the present case four—guide segments  14  which with straight guide surfaces in pairs guide one respective locking bar  16  laterally in the radial direction. The locking bars  16 —in the present case a total of four—are arranged offset—in the present case respectively by 90°—to one another in a constructional space defined between the two fitting parts  11  and  12 . The locking bars  16  are provided on their radial external end with a toothing which may come (fall) into engagement with a toothed rim  17  of the first fitting part  11  configured as a ring gear. When the toothed rim  17  and the locking bars  16  cooperate, the fitting  10  is locked. 
     The first fitting part  11  is arranged in a recess of the second fitting part  12  and is encompassed radially externally thereby, whereby the two fitting parts  11  and  12  bear one another. In this case, the radial external edge region of the first fitting part  11  is arranged with the toothed rim  17  in the radial direction between the guide segments  14  and the radial external edge region of the second fitting part  12  (serving to mount the first fitting part  11 ). In the case of high loads, for example in the event of a crash the first fitting part  11 —after deformation—may come to bear with its toothed rim  17  against the guide segments  14  which are located closer in the loading direction, said guide segments having surfaces correspondingly (concentrically) curved relative to the toothed rim  17 . This increases the strength of the fitting  10 . 
     The first fitting part  11  may be mounted in the second fitting part  12 . However, the relationships could be exactly reversed, i.e. the second fitting part  12  may be mounted on the first fitting part  11 . In principle, however, both arrangements are equivalent. 
     A driver  21  is arranged in the center of the fitting  10 . The driver  21  extends in the direction of the axis A and is provided about the axis A with a through-opening. In the present case, the driver  21  is a one-piece plastics component. At its end oriented toward the first fitting part  11 , the driver  21  has a first cylinder portion  21   a , and with the outer surface thereof the driver  21  being rotatably mounted on the first fitting part  11 , more specifically in a central opening thereof. In the direction of the second fitting part  12  a first profiled portion  21   b , a second profiled portion  21   c , a second cylinder portion  21   d , a third cylinder portion  21   e  and four driver cams  21   f  adjoin the first cylinder portion  21   a  in this sequence. 
     An eccentric  27  is located fixedly in terms of rotation on the first profiled portion  21   b  of the driver  21  which is designed to be approximately square in cross section, said eccentric being arranged in the constructional space defined between the fitting parts  11  and  12 . A spring arrangement  35 , for example one or two spiral springs nested in one another, is arranged in a central receiver of one of the two fitting parts  11  and  12 , in the present case of the second fitting part  12 , and in the present case supported externally thereon. The spring arrangement  35  acts on the eccentric  27 , in the present case by being located on the inside fixedly in terms of rotation on the second profiled portion  21   c  of the driver  21  which is designed to be approximately square in cross section. Such a spring arrangement  35  is disclosed, for example, in DE 10 2005 046 807 B3. The eccentric  27  loaded by the spring arrangement  35 , acts on the radially movable locking bars  16  and loads said locking bars such that they are forced radially outwards in order to fall into engagement with the toothed rim  17 , whereby the fitting  10  is locked. 
     The second cylinder portion  21   d  of the driver  21  protrudes through a circular opening of the second fitting part  12  out of the fitting  10  so that the third cylinder portion  21   e  adjacent to the second cylinder portion  21   d  is located entirely outside the constructional space of the fitting  10  formed by the first fitting part  11  and the second fitting part  12 . The external diameter of the third cylinder portion  21   e  is slightly smaller than the external diameter of the second cylinder portion  21   d  so that in the transition region between the second cylinder portion  21   d  and the third cylinder portion  21   e , an annular surface  21   s  oriented perpendicular to the axis A is present. 
     The third cylinder portion  21   e  has at its end remote from the second cylinder portion  21   d , a front face  21   e ′. Four driver cams  21   f  are equally distributed over the circumference of the front face  21   e ′ and radially outwardly fastened thereto. The defining surfaces of the driver cams  21   f  facing radially outward are located on an imaginary extension of the outer surface of the third cylinder portion  21   e  and extend from the front face  21   e ′ in the axial direction away from the third cylinder portion  21   e.    
     In the region of the second cylinder portion  21   d  and the third cylinder portion  21   e , a fastening ring  24  is provided on the driver  21 , in the present case said fastening ring consisting of plastics and being fastened by means of ultrasonic welding to the driver  21 . 
     A control disk  36  is axially arranged in the constructional space between the locking bars  16  and the first fitting part  11  and in the present case is located fixedly in terms of rotation on the eccentric  27 . The control disk  36  has—in the present case four—control tracks which in each case cooperate with a lug  38  of each locking bar  16 . The lugs  38  protrude in this case in the axial direction from the locking bars  16  assigned thereto. With a rotation (by a few degrees) of the driver  21 —and the eccentric  27  driven thereby and the control disk  36 —counter to the force of the spring arrangement  35  the control disk  36  pulls the locking bars  16  radially inwards i.e. out of the toothed rim  17 , whereby the fitting  10  is unlocked and the two fitting parts  11  and  12  are able to be rotated relative to one another about the axis A. The backrest  4  is now pivotable about the axis A, in order to adjust its inclination, i.e. in order to adopt a different position of use. 
     The backrest  4  is able to be adjusted in inclination by means of the described fitting  10 , i.e. it is able to adopt different positions of use. Additionally or alternatively, the backrest  4  may be freely pivoted, i.e. pivoted forward, in order to facilitate entry to a rear seat row of a two-door or three-door motor vehicle, for example, or to be transferred from the upright position of use into a horizontal table position. The fitting  10  is thus only intended to be locked in a few selected positions. It increases the operating comfort if, after having been unlocked, the fitting  10  does not have to be held during the entire pivoting process into such a selected position. To this end, in the fitting  10 , between the control disk  36  and the first fitting part  11  about the axis A, an annular freely pivoting control element, not shown in the figures, is optionally provided, said control element being connected fixedly in terms of rotation to the first fitting part  11 . The freely pivoting control element has stop tracks which cooperate with the lugs  38  of the locking bars  16 , by limiting the movement thereof radially outwardly or by permitting said lugs to engage therein unhindered. In order to be able to pivot the backrest  4  freely by more than the angle between two locking bars  16 , the lugs  38  of the locking bars  16  are alternately arranged at different intervals radially outwardly or radially inwardly on the locking bars  16  assigned thereto, so that adjacent lugs  38  cooperate with different stop tracks. Accordingly, two different embodiments of the locking bars  16  are provided. Details are described in DE 10 2006 015 560 B3. 
     The fastening ring  24  has a plurality of different functional regions, in the present case four. Directly axially adjacent to the second fitting part  12 , the fastening ring  24  has an external profile  24   a , in the present case a square with rounded corners, which is configured on the circumference of a radially protruding material part. On the free end remote from the second fitting part  12 , the fastening ring  24  has a collar  24   b  which also protrudes radially. Radially inside the collar  24   b , i.e. in a recess of the fastening ring  24 , an internal profile  24   c  is formed, in the present case as a wedge profile with four-fold symmetry. Radially on the inside, the hollow fastening ring  24  is provided with a passage  24   d  which is designed to be slightly stepped in the axial direction. One of the steps is designed as an edge  24   s . When mounting the fastening ring  24  on the driver  21 , the passage  24   d  is pushed over the second cylinder portion  21   d  and the third cylinder portion  21   e  of the driver  21  until the edge  24   s  bears against the circumference of the annular surface  21   s . At this point, during the ultrasonic welding, a circumferential welded connection is produced between the fastening ring  24  and the driver  21 , as is disclosed in principle in DE 10 2008 024 853 A1. The gap shown symbolically in  FIG. 4  between the annular surface  21   s  and the edge  24   s  serves only for illustration of the welding point, but is no longer present after the welding. 
     The outer profile  24   a  is provided for optional cooperation with an indicator, in a manner which is fixed in terms of rotation. The indicator is a ring with a radially protruding pointer, wherein the ring has a profile adapted to, and preferably cooperating positively with, the outer profile  24   a . The indicator provides the angular position of the driver  21  and thus of the eccentric  27 , which in turn is an indication of whether the locking bars  16  acted upon by the eccentric  27  are radially external or radially internal i.e. the fitting  10  is locked or unlocked. 
     A groove  24   g  is formed on the fastening ring  24 , axially between the outer profile  24   a  and the collar  24   b , said groove, for example, being 1 mm deep relative to the collar  24   b . The collar  24   b  is provided for a clip connection with the component to be clipped on. Due to the groove  24   g , the collar  24   b  may be engaged from behind in the axial direction in order to create the clip connection. The component to be clipped on which has one or more hook-shaped projections for cooperation with the collar  24   b  is, for example, an actuating lever  5 . 
     The internal profile  24   c  is provided for a connection which is fixed in terms of rotation to a part acting on the driver  21 , in the present case said actuating lever  5  which has a profile on a bearing portion adapted to, and preferably cooperating positively with, the internal profile  24   c . The actuating lever  5  is, as a result, mounted on the fastening ring  24  by means of the bearing portion and connected fixedly in terms of rotation to the driver  21  and axially secured to the collar  24   b  by means of the clip connection. 
     The use of the functional regions described above of the fastening ring  24  (external profile  24   a , collar  24   b , internal profile  24   c  and passage  24   d ) require a defined angular position of the fastening ring  24  which is subject to as little tolerance as possible relative to the driver  21 . In order to achieve this during the mounting process, the collar  24   b  of the fastening ring  24  has four first cams  24   n  inside the passage  24   d  which in the radial direction are oriented toward the axis A, and cooperate with the driver cams  21   f  of the driver  21 . To this end, the driver cams  21   f  have in each case a centering surface  21   f  which in each case in the circumferential direction bear against a bearing surface  24   n ′ of the first cams  24   n . As a result, the angular position of the fastening ring  24  relative to the driver  21  is clearly determined before the components are connected together, preferably ultrasonically welded. 
     As shown in  FIG. 8 , one respective centering angle Z, in the present case 4°+1-1°, is provided between the centering surface  21   f  and the bearing surface  24   n ′, by the bearing surfaces  24   n ′ being inclined in this case relative to a line parallel to the axis A about this centering angle Z, whilst the centering surfaces  21   f  extend axially parallel. However, modifications are also possible in which only the centering surfaces  21   f  are inclined or said centering surfaces are additionally inclined by an angle relative to a line parallel to the axis A. 
     In a further modification of the exemplary embodiment, the bearing surface  24   n ′ in the axial direction is only inclined in a first partial portion in regions relative to a line parallel to the axis A. A second partial portion extending parallel to the axis A in the mounted state is parallel to and in contact with the centering surface  21   f.    
     The driver cam  21   f  has on its end remote from the front face  21   e ′, on its internal edge, a circumferential chamfer  21   g , which serves for centering the fastening ring  24  when the fastening ring  24  is first pushed onto the driver  21 . 
     While pushing the fastening ring  24  onto the driver  21 , shown in  FIGS. 9   a  to  9   c , a slight relative angular deviation about the axis A which is potentially present may be compensated by the bearing surfaces  24   n ′ of the first cams  24   n  inclined by the centering angle Z sliding along the inclined centering surfaces  21   f  when pushed in the axial direction onto the centering surfaces  21   f  of the driver cams  21   f , and as a result being rotated into the correct angular position. 
     Optimal centering in both circumferential directions is achieved by two cam pairs being provided, in each case consisting of a driver cam  21   f  and a first cam  24   n , wherein the driver cams  21   f  and the first cams  24   n  bear against one another in the respectively opposing circumferential direction. To this end, the cam pairs are configured mirror-symmetrically relative to one another. 
     To this end the fastening ring  24  preferably has three or more, in the present case six, second cams  24   m  which protrude inwardly in the passage  24   d  in the region of the outer profile  24   a  in the radial direction and in the mounted state of the fitting  10  bear against the second cylinder portion  21   d  of the driver  21 . As a result, in the mounting process the fastening ring  24  when pushed onto the driver  21  in the radial direction is positioned exactly opposite the driver  21 . During the mounting process, initially the second cams  24   m  pass the outer face of the third cylinder portion  21   e , which has a slighter smaller diameter relative to the second cylinder portion  21   d . If the first cams  24   n  already cooperate with the driver cams  21   f  to align the relative angular position of the driver  21  and fastening ring  24 , the second cams  24   m  come into contact with the second cylinder portion  21   d  and center the driver  21  and the fastening ring  24  in the radial direction relative to one another, by elastic and/or plastic deformation of the second cams  24   m.    
     Adjacent to the second cams  24   m  a small gap exists between the fastening ring  24  and the driver  21 , said gap, in particular, being filled with weld deposit produced during the ultrasonic welding process. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.