Abstract:
A headrest arrangement ( 22 ) for a vehicle seat is provided with at least one backrest ( 10 ) and a headrest device ( 14 ). A mechanical transmission device is included for transformation of a deformation of the backrest ( 10 ) into a movement of the headrest device ( 14 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates to a headrest arrangement for a vehicle seat comprising at least one backrest and a headrest device. 
     BACKGROUND OF THE INVENTION 
     Vehicle seats often comprise headrests which are fastened to the upper end of a backrest. In this context, different fastening possibilities can be considered. For example, the headrest can be connected fixedly to the backrest but can also be height-adjustable and pivotable in order to be adapted to the anatomy of different vehicle passengers. 
     Conventional vehicle seats have the problem that the spacing between the back of the head of a vehicle passenger and the headrest can possibly be very large depending on the seating position of the vehicle passenger. This problem occurs especially, but not exclusively, in regard to vehicle seats where the incline of the backrest can be selected differently. 
     A large spacing between the back of the head and the headrest, however, is very dangerous for the vehicle passengers in the case of an accident, especially in the case of a rear impact. In the case of an impact, a very great relative acceleration between the headrest and the head of the vehicle passenger occurs which results in a very hard impact of the back of the head on the headrest. Severe head injuries can be the result. 
     A solution for preventing such a great spacing between the back of the head and the headrest is proposed in DE 298 08 831 U1. The vehicle seat described therein comprises a two-part backrest. An upper part of the backrest on which the headrest is fastened is rotatably embodied relative to the lower part of the backrest. In this connection, the upper part is forced by a spring into a forward rest position and is pivotable toward the back when the vehicle passenger rests against it. A disadvantage of this system is the high manufacturing expenditure. In order to be able to ensure a protection as effective as possible in the situation of accidents, not only the installation of a spring means but also of a shock absorber is required. Moreover, the construction described here is only suitable to a limited extent for the vehicle backseats. Finally, the movable construction of the backrest can be perceived as uncomfortable by some vehicle passengers. 
     SUMMARY AND OBJECTS OF THE INVENTION 
     It is therefore an object of the present invention to provide a headrest arrangement for a vehicle which reduces the injury risk for the neck area and back area of the neck of the vehicle passenger in an accident and is furthermore characterized by a simple configuration. 
     According to the invention, a headrest arrangement is provided for a vehicle seat comprising at least one backrest and a headrest device. A mechanical transmission device is provided for the transformation of a deformation of the backrest into a movement of the headrest device. 
     The invention resides substantially in that a mechanical transmission device transforms a deformation of the backrest into an oppositely oriented movement of the headrest device so that the headrest device is moved toward the back of the head of the vehicle passenger. The deformation of the backrest is effected by the inertia forces which the vehicle passenger exerts onto the backrest, for example, in the situation of a rear impact. Accordingly, this is a purely passive system which requires no active components. The advantage of a minimal service expenditure can therefore be realized together with a very high reliability of the system. Moreover, also with regard to manufacturing technological considerations, the seat and headrest arrangement according to the invention can be relatively easily manufactured because it requires only a few component groups. 
     An especially preferred configuration of the headrest arrangement can be realized when for forming the transmission device the backrest comprises a deformable support structure which is supported on a contact device in a bending-resistant transition area between the backrest and the headrest device. The support structure forms the mechanically stable part of the backrest and can be upholstered for improving the comfort of the seat. The support structure deforms when an accident occurs and, by means of the mechanical transmission device, the headrest device is moved. The support structure can be formed in any suitable way, for example, as a surface member or as a grate member and can be subsequently embedded in foam in a known manner with an upholstery material. A surface member configuration of the support structure can also be provided with holes so that embedding in foam can be realized more easily and more permanently. 
     It has been proven to be especially advantageous to form the support structure as a shell-like support shell. This makes it possible in an especially easy way to adapt the backrest to the shape of the anatomy of the back and to thus realize an especially comfortable vehicle seat. It is especially advantageous that with such a backrest the upholstery portions can be provided over the entire surface area of the backrest with substantially the same thickness which is very advantageous with respect to manufacturing technological aspects. 
     The headrest device can be connected by fastening means with the support structure so that known headrest devices can be employed for realizing the headrest arrangement. 
     An especially simple configuration results when at least one part of the headrest device is formed by a correspondingly shaped part of the support structure. Such a one-part, integral configuration allows an especially inexpensive production. A possibly required stiffening in the transition area between the support structure and the headrest device can be realized, for example, in that the material in the area of the headrest device has a greater cross-section or that in the transition area recesses are provided in which additional reinforcement elements can be inserted. 
     It is especially advantageous to provide a stop device which limits the deformability of the backrest. With such a stop device, the movement of the backrest can be limited to such an extent that, when an accident occurs, the upper body remains in a substantially vertical position in which the accelerations occurring during an impact present the most minimal injury risk for the vehicle passengers. At the same time such a stop device can also represent the contact device of the mechanical transmission device, which in cooperation with the support structure of the backrest, transforms the deformation of the backrest into a movement of the headrest device. For example, in the simplest case, the stop device can be comprised of a profile which is connected to the car body and on which, in the case of the headrest device being connected directly to the backrest, the transition area between the headrest and the backrest is supported. For example, a rearwardly oriented deformation of the backrest is then transformed in the simplest manner into a forward movement of the headrest device. However, other embodiment variants of the stop device are possible, for example, the use of a rotary joint. 
     In order to avoid an excessive deformation of the backrest with respect to the anatomy of the back, which could result in itself in injuries in the back area of the vehicle passenger, an especially preferred embodiment of the stop device is characterized in that it is of a cavity shape. Accordingly, the backrest, in its maximally deformed position, is also cavity-shaped so that the risk of injury is reduced. Such a cavity-shaped stop device can especially be substantially sheet-like. Since, generally, in any type of vehicle seat a structure is to be provided that is as stable and as sheet-like as possible and provides protection against loose parts which could fly forward during an accident, such a cavity-shaped stop device can be realized without great additional expenditure. 
     It is a further advantage when for the headrest arrangement the configuration of the support structure of the backrest, respectively, the materials for the backrest as well as for the support structure are selected such that the backrest acts as an energy-dissipating means. Accordingly, already during the deformation of the backrest when an accident occurs, a deceleration of the vehicle passengers can be achieved so that the maximum acceleration forces acting on the vehicle passenger are reduced. The vehicle seat acts thus as an additional crumple zone and is thus especially safe. 
     When the headrest arrangement is provided on a backseat, the backrest can be used at the same time for forming a divider between the passenger compartment and the trunk space. 
     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 cross-sectional side view of a first embodiment of a headrest arrangement in the undeformed state; 
     FIG. 2 is a schematic cross-sectional side view of the headrest arrangement illustrated in FIG. 1 in the deformed state; and 
     FIG. 3 is a cross-sectional side view of a second embodiment of a headrest arrangement in the undeformed state. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular, FIG. 1 shows in a greatly simplified form the essential components of a headrest arrangement  22  which is arranged on a vehicle seat in the back of a vehicle. The headrest arrangement  22  comprises a backrest  10  with a support structure embodied as a support shell  11  on which upholstery  12  is fastened. The attachment of the upholstery  12  can be realized in a known manner, for example, by embedding the support shell  11  in foam. At the upper end of the backrest  10 , a headrest  14  provided as a separate component is located which is fastened by means of fastening rods  13  on the support shell  11 . The attachment of the fastening rods  13  on the support shell  11  is realized in the illustrated embodiment by a screw or clamping connection  15 . The headrest  14  can be connected so as to be movable relative to the support shell  11  or can be rigidly connected to the support shell  11 . 
     The backrest  10  has positioned opposite thereto a stop device  18  with defined stiffness or flexibility. It can be comprised, for example, of profiled sheet metal. In the illustrated embodiment, the stop device  18  is of a shell-like shape. The stop device  18  represents, at the same time, the partition between the trunk space  19  and the passenger compartment. The illustrated stop device  18  has a contact stay  17  on which a transition area  16  of the backrest  10  is supported. This transition area  16  represents the upper part of the backrest  10  in which the backrest  10  has a transition into the securing device of the headrest  14 . 
     In the illustrated embodiment the support shell  11  is planar while the stop device  18 , on the other hand, is shell-shaped. It is also possible to form the support shell  11  as a shell shape and the stop device  18  as a planar member. Also, it is possible to embody the support shell  11  as well as the stop device  18  in a shell shape. 
     As can be seen especially in FIG. 2, the contact stay  17  serves to transform the deformation of the backrest  10 , which occurs in the case of an acceleration by the inertia force caused by the upper body of a to passenger, into a forward movement  21  of the headrest  14 . The inertia force  20  is exerted by the vehicle passenger onto the backrest  10  especially when a rear impact occurs. 
     This deflecting effect cannot only be achieved with a contact stay  17  but also with other suitable stop devices. Moreover, the stop device  18  can not only be embodied as a sheet member but also as a grate member, a net structure or a frame structure. 
     In FIG. 2, an additional function of the stop device  18  can be seen which defines a maximum deformation of the backrest  10 . Accordingly, especially back injuries of the vehicle passengers cannot occur which could result from an excessive but also anatomically unfavorable and irregular deformation of the backrest  10 . Moreover, from the defined maximum deformation a limitation of the forward movement  21  of the headrest  14  results so that an excessively hard impact of the headrest  14  on the back of the head of the vehicle passenger can be prevented. 
     The backrest  10  or the support shell  11  can be comprised of any suitable materials and can be shaped as a sheet member as well as a frame member, grate-like, net-like or provided with a structure but also of a suitable composite material. For a corresponding configuration of the backrest  10  or a corresponding material selection, the backrest  10  acts during its deformation in an energy-dissipating manner. Accordingly, the kinetic energy of the vehicle passenger can be dissipated across a longer travel distance so that the vehicle seat, at least in the case of a back impact, functions as an additional crumple zone. 
     In the illustrated embodiment of the seat and headrest arrangement  22  as a backseat, the stop device  18  functions at the same time as a partition between the trunk space  19  and the passenger compartment. Since such a partition is to be provided in any case and must have a corresponding stability, for example, so that, when an accident occurs, luggage pieces carried within the trunk space will not become an injury liability, an especially simple configuration of the seat and headrest device according to the invention is promoted. The same holds true for the front seats because here also a protection of the vehicle passengers, for example, with respect to objects positioned on the backseat bench, must be provided. 
     In FIG. 3 a headrest arrangement  30  is illustrated which is also suitable as a backseat. In deviation froze the headrest arrangement  22  described with reference to FIG.  1  and FIG. 2, a headrest  31  is formed as an integral part of the backrest  32  such that the upper part of the support structure forms the headrest  31 . In this case, the transition area  33  is also supported on a contact stay  34  which forms the upper edge of a stop device  35  so that in the case of an accident the inertia force  20  exerted onto the backrest  32  is transformed into a forward movement  21  of the headrest  31 . 
     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.