Abstract:
A headrest for use on a motor-vehicle seat back has a base that is secured to the seat back, a head part, and respective base and head guides supporting the head part on the base for displacement in a direction between a rear rest position and a front extended position. A slide is provided between the base and the head part and is movable relative to both the head part and the base on shifting of the head part between the positions. A gear assembly engages both the head part and the base.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a headrest. More particularly this invention concerns a headrest for a motor vehicle. 
       BACKGROUND OF THE INVENTION 
       [0002]    A standard motor-vehicle headrest has a movable head-contact part that is adjustable relative to a fixed base in order to be able to move a front surface of the movable part into the required position with respect to the head of an occupant in the automobile seat. 
         [0003]    A headrest in which a part can be moved relative to a base body between a back and a front position is described in DE 10 2006 016 270. An intermediate sleeve of the headrest has an external thread engaging with a thread of the movable part. The intermediate sleeve also has an internal thread engaging the thread of a base body. A spring element urges the movable part into the front position. Shifting of the movable part is effected by rotation of the intermediate sleeve. 
         [0004]    A headrest in which the movable part is carried by interacting teeth of a base and of the movable part and of a toothed shaft is disclosed in US 2010/0127541. 
         [0005]    Particularly in the case of so-called L-shaped headrests, which are formed in such a way that they can be placed on the seat back of the automobile seat and then project only slightly over the top of the seat back, there is little room available for mounting and guiding the movable part. 
       OBJECTS OF THE INVENTION 
       [0006]    It is therefore an object of the present invention to provide an improved motor-vehicle headrest. 
         [0007]    Another object is the provision of such an improved motor-vehicle headrest that overcomes the above-given disadvantages, in particular whose operating mechanism takes up little space but is rugged and reliable. 
       SUMMARY OF THE INVENTION 
       [0008]    A headrest for use on a motor-vehicle seat back has according to the invention a base that is secured to the seat back, a head part, and respective base and head guides supporting the head part on the base for displacement in a direction between a rear rest position and a front extended position. A slide is provided between the base and the head part and is movable relative to both the head part and the base on shifting of the head part between the positions. A gear assembly engages both the head part and the base. 
         [0009]    In other words, the headrest has a base which is fixed to the seat back of an automobile seat. The base can be retained on the seat back in a height-adjustable manner, for example by at least one support rod. A movable part can be moved along a is movement path relative to the base between a rest position and an extended position. In the extended position, the movable part is moved closer toward the head of an occupant of the seat relative to the rest position. 
         [0010]    The movable part is mounted on the base by a mounting device. The guide and mount comprises a first guide associated with the base and second guide associated with the movable part as well as a telescopic device or slide. The slide can be moved relative to the base and relative to the movable part. The slide comprises at least one telescopic element which engages with first guide of the base and with the second guide of the movable part and projects partially out of the guide of the base in the extended position. The telescopic element can be slid longitudinally, for example parallel to the movement path of the movable part. The position of at least one telescopic element of the slide is controlled by the gear assembly. 
         [0011]    Within the meaning of the invention, the guide and mount includes means for mounting and for guiding the movable part, for example along the movement path and in a predetermined direction. 
         [0012]    Within the meaning of the invention, telescopic means that the first guide, the second guide and the slide can be moved between a nested and an extended position. In the extended position, there is a slight overlap relative to the nested position between the slide and the first guide and between the slide and the second guide. The first guide, the second guide and the at least one telescopic element are coaxial, for example when moving along their movement path. 
         [0013]    The headrest comprises the gear assembly that controls the telescopic element or slide. The telescopic element is controlled, for example, depending on the position of the movable part. A position of the telescopic element, for example, is associated with each position of the movable part. 
         [0014]    The headrest with the characteristics according to the invention requires little installation space and yet guarantees a functionally reliable guiding of the movable part. 
         [0015]    According to a first embodiment, the gear assembly comprises the first guide and the second guide as well as the toothed elements associated with and interacting with the slide. The toothed elements can be racks that extend over a substantial part of the width of the headrest. According to an alternative embodiment, toothed elements, for example, can be formed at least in two different side regions of the base, the movable part and the telescopic element of the headrest. At least two movable toothed elements are, for example, movably connected in such a way that the side regions always execute the same movement. This guarantees precise guiding. Jamming of the movable part and the slide can also be avoided. 
         [0016]    A further embodiment is characterized in that the gear assembly comprises racks formed on the base and on the movable part and at least one gear associated with the slide. The gear engages with the racks of the base and of the movable part. The gear is fixed to but rotatable on the telescopic element, for example. The base and the movable part each have at least two racks, for example, that are on opposite sides of the headrest. Longitudinal center axes of the racks, for example, extend parallel to the movement path of the movable part. The telescopic unit comprises, for example, at least two gears on in different sides of the headrest. The gears are movably connected, for example. The gears can be fixed on a common shaft, for example. The shaft is journaled on the telescopic element, for example. Each gear interacts, for example, with a respective rack of the base and with a respective rack of the movable part. 
         [0017]    Another embodiment of the invention is characterized in that the base and the movable part as well as possibly the slide comprise drawer-like interacting mounting structures. For example, at least one mounting structure of the movable part and at least one mounting structure of the telescopic element can be nested in a drawer-like manner with a mounting structure of the base in the rest position. The mounting structure of the movable part and the telescopic element can, for example, be moved to an extended position which corresponds to the extended position of the movable part, wherein the mounting structures of the movable part, the telescopic element and the base overlap one another to a lesser extent, that is the overlap of two interacting mounting is structures is in each case less than in the nested position. 
         [0018]    Another embodiment is characterized in that guide surfaces of at least one mounting structure are designed approximately in a C-shape. The C-shaped mounting structure has at least two mounting and guide surfaces arranged at an angle, in particular at right angles, to each other. For example, the mounting structure comprises three surfaces which, for example, are designed as sliding and guide surfaces, wherein two opposing surfaces are in each case arranged at right angles, for example, to a third surface. In this way, force can be transmitted in several directions. The first guide, the second guide and the slide can, for example, comprise at least two C-shaped mounting structures in each case. The two mounting structures can, for example, be designed mirror-imaged in both side regions of the headrest. In this way, for example, the degrees of freedom of the movable part and of the telescopic element can be restricted so that only a movement along the movement path between the rest position and the extended position is possible. 
         [0019]    According to a further embodiment of the invention, a one-way catch that can be locked or released is provided. In the locking position, the one-way catch prevents movement of the movable part in at least one direction. The one-way catch is designed as a latch, for example. The one-way catch comprises at least one row of teeth for example, formed on the base, and at least one locking element mounted on the movable part and movable between a locking position and a release position. In the locking position, movement of the movable part is not possible in at least one direction. For example, movement of the movable part is not possible in the locked position. According to an alternative embodiment, movement is possible in one direction, for example toward the extended position. In the release position, movement of the movable part is possible toward the extended position and toward the rest position. In the locking position, the one-way catch is loaded in a reset position, for example, and in the release position is adjustable by an actuating device. The actuating device comprises an actuating element, for example, on the base or the movable part. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0020]    The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
           [0021]      FIG. 1  is a perspective view of a headrest according to the invention; 
           [0022]      FIG. 2  is a side view of the headrest in the starting position; 
           [0023]      FIG. 3  is a side view of the headrest in the extended position; 
           [0024]      FIGS. 4 and 5  are sections taken along respective line IV-IV and V-V of  FIGS. 2 and 3 ; 
           [0025]      FIG. 5  is a section taken along line VI-VI of  FIG. 2 ; 
           [0026]      FIGS. 7 and 8  are sections taken along respective line VII-VII and VIII-VIII of  FIGS. 4 and 5 ; 
           [0027]      FIG. 9  is a partly sectional bottom view of the headrest; 
           [0028]      FIG. 10  is a schematic side view of the headrest and a back of an automobile seat in several different positions; and 
           [0029]      FIG. 11  is a sectional detail view of the headrest of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    As seen in  FIG. 1 , a headrest  10  has support rods  11   a  and  11   b  that are vertically adjustable in the back of a vehicle seat such as shown at  57  in  FIG. 10 . The headrest  10  can be set at any of a plurality of vertically offset positions by means of rods and adjusted in vertical directions z 1  and z 2  with the assistance of vertically spaced notches  12  in the rods  11   a  and  11   b . The headrest  10  has a fixed base  13  and a movable head-contact part  14 . The movable part  14  is provided with upholstery P and forms a generally vertical front head-contact surface  15 . The upper ends of the support rods  11   a  and  11   b  are fixed in downwardly open sockets  26   a  and  26   b  ( FIG. 5 ) of the base  13 . 
         [0031]      FIG. 2  shows that the movable part  14  is of inverted L-shape with a horizontally forwardly projecting upper leg  16  and a downwardly projecting back leg  17 . A back face  18  of the leg  16  can therefore engage against a front face of the unillustrated seat back and a lower face  19  of the leg  17  can engage against an upper face of the seat back that is not shown in  FIG. 2 . The headrest  10  then only extends above the seat back slightly so that the view of the driver to the rear is only impaired to a small extent by the headrest  10 . 
         [0032]    The movable part  14  is shown in  FIG. 2  in a retracted or rest position from which it can be moved into a forwardly extended position shown in  FIG. 3  by exerting a force on the movable part  14  in a horizontal forward direction x 1  that is sufficient to overcome the holding force of a one-way catch  59  designed as a one-way catch. Movement of the movable part  14  in a rearward horizontal direction x 2  into the rest position is normally prevented by the latch  59  and is only possible when a button  20  is pressed. The movable part  14  is mounted on the base  13  by a mount  21  ( FIG. 6 ). The base  13  is of rectangular section and forms four sliding surfaces  22   a - d , of which only surfaces  22   a ,  22   c , and  22   d  are visible in the drawing. 
         [0033]    As can be seen in  FIGS. 5 and 9 , horizontally confronting rows  24   a  and  24   b  of ratchet teeth are formed on the base  13 . The row  24   a  coacts with a locking element  25   a  and the row  24   b  with a locking element  25   b  of the movable part  14 . The rows  24   a  and  24   b  of sawteeth along with the locking elements  25   a  and  25   b  form the one-way latch  59 . 
         [0034]      FIG. 4  shows that parallel lower racks  23   a  and  23   b  are formed on the movable part  14  with upwardly directed teeth. Longitudinal center axes k of the lower racks  23   a  and  23   b  are parallel to the horizontal front-to-back x-axis of directions x 1  and x 2 . The lower racks  23   a  and  23   b  are straight and their teeth are parallel to the horizontal and transverse y-axis of the directions y 1  and y 2 . The flanks of the teeth of the lower racks  23   a  and  23   b  can withstand forces in the directions x 1  and x 2 . Gears  27   a  and  22   b  mesh with the lower racks  23   a  and  23   b  and are securely fixed to a common shaft  28  so the shaft  28  and the gears  27   a  and  27   b  rotate jointly about an axis of rotation a. The shaft  28  is mounted in bearings  29   a  and  29   b  of a slide  30 . 
         [0035]    According to  FIG. 6 , the gears  27   a  and  27   b  extend upward through respective apertures  31   a  and  31   b  in the slide  30  and engage respective upper racks  32   a  and  32   b  formed on the base  13 . The upper racks  32   a  and  32   b  are substantially identical to the racks  23   a  and  23   b , but have downwardly directed teeth. 
         [0036]    The slide  30  is of bent sheet metal and has two U-section edge regions  33   a  and  33   b  that can move front-to-back, that is in directions x 1  and x 2 , in U-section guides  34   a  and  34   b  of the base  13  while engaging around guide edges  35   a  and  35   b  of the movable part  14 . 
         [0037]    The gears  27   a  and  27   b  rotationally coupled by the shaft  28  and mounted on the slide  30  engage with the respective upper racks  32   a  and  32   b  of the base  13  and with the respective lower racks  23   a  and  23   b  of the movable part  14 , thus forming a gear assembly G. The gears  27   a  and  27   b  are separated from each other in the directions y 1  and y 2  by a large spacing D so that they prevent the base  13 , the movable part  14  or the slide  13  from canting relative to one another about the vertical z-axis of directions z 1  and z 2 . It is therefore impossible for the movable part  14  or the slide  30  to jam, as its sides always move synchronously. The slide  30  is moved by the gear assembly G, depending on the adjustment position of the movable part  14 , into a defined position in which the movable part  14  is secured by the one-way catch  59 . 
         [0038]    The guides  34   a  and  34   b  of the base  13  have respective planar guide faces  36   a ,  37   a ,  38   a  and  36   b ,  37   b ,  38   b  that are all provided with guide ribs  39  which project perpendicularly from the respective planes and that extend in the horizontal directions x 1  and x 2 . The guide ribs  39  of the faces  36   a ,  37   s ,  38   a  and  36   b ,  37   b , and  38   b  form sliding surfaces for outer faces  40   a ,  41   a ,  42   a  and  40   b ,  41   b , and  42   b  of the respective edge regions  33   a  and  33   b  of the slide  30 . The guides  34   a  and  34   b  are of a square C-shape with a substantially right angle between the faces  36   a ,  36   b  and  37   a ,  37   b  and between the faces  37   a ,  37   b  and  38   a ,  38   b . A similar substantially right angle is likewise formed between the sliding surfaces  40   a ,  40   b  and  41   a ,  41   b  and the sliding surfaces  41   a ,  41   b  and  42   a ,  42   b.    
         [0039]    The guide edge  35   a  is provided with outer surfaces  43   a ,  44   a  and  45   a , wherein in each case the outer surfaces  43   a  and  44   a  and the outer surfaces  44   a  and  45   a  are arranged approximately at right angles to one another. The guide edge  35   a  is encompassed by the C-shaped edge region  33   a  so that the outer surface  43   a  acts together with an inner surface  46   a  of the edge region  33   a . Furthermore, the outer surface  44   a  and the inner surface  47   a  and the outer surface  45   a  and the inner surface  48   a  act together. As the guide edge  35   b  is designed in the same way as a mirror image, outer surfaces  43   b ,  44   b  and  45   b  act together with inner surfaces  46   b ,  47   b  and  48   b  in a corresponding manner. 
         [0040]    Movement of the movable part  14  is guided by the edge regions  33   a ,  33   b  and the guide edges  35   a ,  35   b  as described above. Movement of the movable part  14  in the directions z 1 , z 2 , y 1 , y 2  and rotation about the z-axis and the y-axis is also effectively prevented, and smooth nonbinding guiding is guaranteed for movement in direction x 1 , x 2 . 
         [0041]    An upholstery support  49  having an outer surface  50  provided with upholstery P can be seen in  FIG. 6 . An inner surface  51  has ribs  52  that extend in the directions x 1  and  2   x  and can slide on an outer surface  22  of the base  13 . The inner surface  51  is of C-shape and has generally planar regions  51   a ,  51   b  and  51   c . An obtuse or a right angle is formed between the regions  51   a  and  51   b  and between the regions  51   a  and  51   c . The outer surface  22  has complementary generally planar regions  22   a ,  22   b  and  22   c , but this outer surface  22  is not provided with slide ribs. 
         [0042]    Furthermore as shown in  FIG. 9 , the movable part  14  is provided with a stop  54  that acts together with the shaft  28  (not is shown in  FIG. 6 ) to limit relative movement between the movable part  14  and the slide  30 . 
         [0043]      FIG. 7  shows the movable part  14  in the rest position, with the movable part  14 , the slide  30  and the base  13  telescopically nested in one another. 
         [0044]    In  FIG. 8 , the base  13 , the slide  30  and the movable part  14  are shown in the extended position in which the slide  30  projects partially out of the base  13  in the direction x 1 . 
         [0045]      FIG. 9  shows the underside of the headrest  10 , the support rods  11   a  and  11   b  not being shown for the sake of clarity. The movable part  14  is in the extended position. The stop  54  is in contact with the shaft  28  and prevents further movement of the movable part  14  in the direction x 1  relative to the slide  30 . The locking elements  25   a  and  25   b , which are movably mounted on the movable part  14 , are part of the above-mentioned one-way catch  59  that in the locked position allows movement of the movable part  14  in the direction x 1  but prevents movement in the direction x 2 . According to  FIG. 9 , the locking element  25   a  is in a latch recess  56   a  formed in an end of the tooth row  24   a  and the locking element  25   b  in a latch recess  56   b  of the tooth row  24   b.    
         [0046]    As long as the locking elements  25   a  and  25   b  act together with the rows  24   a  and  24   b  of teeth, movement is possible in direction x 1  without pressing the button  20 . When the locking elements  25   a  and  25   b  engage with the latching recesses  56   a  and  56   b , a movement of the movable part  14  is not possible without pressing the button  20 . The locking elements  25   a  and  25   b  can is only be released from the latching recesses  56   a  and  56   b  by pressing the button  20 . When the locking elements  25   a  and  25   b  no longer engage with the latching recesses  56   a  and  56   b , the movable part  14  can be moved in the rearward direction x 2  toward the rest position. 
         [0047]    In the embodiment shown in  FIGS. 1 to 9 , the movable part  14  is guided in a straight line when moving between the rest position and the extended position. 
         [0048]    A second embodiment is shown in  FIGS. 10 and 11 . According to  FIG. 10 , a seat back  57  of an automobile seat can be pivoted about an axis not shown in  FIG. 10  but extending parallel to the horizontal transverse y-axis of the directions y 1  and y 2 . In a first position E 1  of the seat back  57  (see dashed outlines), the movable part  14  is shown in the rest position. The head contact surface  15  is at a spacing B from a head  58  of the occupant. If the seat back is pivoted to position E 2 , the movable part  14  must be displaced relative to the base  13  so that the head contact surface  15  assumes the spacing B from the head  58 . 
         [0049]    By guiding the movable part  14  on a curved path when moving between the rest position and the extended position, a change in an angle α between a vertical V parallel to the z-axis and the head contact surface  15  caused by the pivoting movement of the seat back  57  can be maintained approximately constant. As implied in  FIG. 11 , in the second embodiment, the mounting structure  34 ′ of the base  13 , the guide edge  35 ′ of the movable part  14  and the edge region  33 ′ of the slide  30  are curved.