Patent Abstract:
A rotational device ( 10 ) for a vehicle seat includes a base element ( 20 ) and a seat part support ( 30 ) which can be rotated about a rotational axis (S) with respect to the base element ( 20 ). At least three rolling bearings ( 61, 62, 63 ) are provided to rotationally support the seat part support ( 30 ).

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a United States National Phase Application of International Application PCT/EP2014/071739 filed Oct. 10, 2014 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Applications 10 2013 221 095.7 filed Oct. 17, 2013 and 10 2014 201 454.9 filed Jan. 28, 2014, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a rotational device for a vehicle seat having a base component and a seat part support which is rotatable about a rotation axis relative to the base component. The invention also relates to a vehicle seat having such a rotational device. 
     BACKGROUND OF THE INVENTION 
     A rotational device of the type in question and a vehicle seat of the type in question are known from DE 10 2011 012 973 B3. The vehicle seat comprises a base component and a seat part support which is rotatable relative to the base component about a rotation axis. The seat part support is rotatably mounted about a rotation axis by means of two roller bearings and a sliding bearing. Temporary deformations of the seat part support may occur due to excitations or oscillations occurring during driving, as a result of which balls of the roller bearings temporarily lose contact with the seat part support. This can give rise to disturbing noises. 
     A rotational device of the type in question and a vehicle seat of the type in question are also known from DE 10 2010 053 802 B3. 
     SUMMARY OF THE INVENTION 
     A problem addressed by the invention is that of improving a rotational device and a vehicle seat of the type mentioned at the outset, in particular that of increasing a pretensioning force by means of which the seat part support is braced relative to the base component and, as a result, avoiding disturbing noises, without increasing frictional forces which occur upon rotation of the seat part support. 
     According to of the invention a rotational device of the type in question for a vehicle seat comprises a base component and a seat part support which is rotatable about a rotation axis relative to the base component. The base component has a preferably plate-like shape and serves for fastening the vehicle seat in the vehicle. A seat unit can be fastened to the seat part support, which likewise has a preferably plate-like shape. At least three roller bearings are provided for the rotatable bearing of the seat part support. 
     In this way, a more uniform distribution of pressure and distribution of force to the roller bearings is achieved, and disturbing noises caused by vibrations are avoided. 
     The seat part support is preferably shaped like a plate, a first roller bearing being arranged on a flat face of the seat part support, and a second roller bearing and a third roller bearing being arranged on the opposite flat face of the seat part support. 
     Advantageously, the roller bearings are each arranged in a circular track, wherein the first roller bearing extends at a first bearing distance circularly around the rotation axis, the second roller bearing extends at a second bearing distance circularly around the rotation axis, and the third roller bearing extends at a third bearing distance circularly around the rotation axis. The bearing distances each define a radius of the corresponding circular track. 
     According to an advantageous embodiment of the invention, the first bearing distance is smaller than the second bearing distance and larger than the third bearing distance. In the radial direction with respect to the rotation axis, the first roller bearing thus lies between the second roller bearing and third roller bearing. A force introduced via the first roller bearing is thus distributed to the second roller bearing and the third roller bearing. 
     To secure the seat part support, a locking disk is advantageously provided, which is rigidly connected to the base component. The locking disk likewise has a preferably plate-like shape. The locking disk is preferably screwed onto the base component. 
     If the seat part support is arranged between the base component and the locking disk, the seat part support is secured, and a movement of the seat part support in the direction of the rotation axis is prevented. 
     It is preferable that exactly one roller bearing is arranged between the locking plate and the seat part support. Preferably, exactly two roller bearings are arranged between the base component and the seat part support. 
     According to an advantageous embodiment of the invention, the roller bearings are designed as ball bearings and have balls that run in circular ball raceways. 
     According to an advantageous embodiment of the invention, a U-shaped catch hook is provided in order to prevent the seat part support being moved away from the base component. 
     According to an advantageous embodiment of the invention, the catch hook bears on the seat part support and is rigidly connected thereto. 
     According to another advantageous embodiment of the invention, the catch hook is arranged behind the seat part support as seen in the direction of travel x. 
     According to an advantageous embodiment of the invention, the catch hook is screwed onto the seat part support. 
     The problem is also solved by a vehicle seat having at least one rotational device according to the invention. 
     The invention is explained in more detail below on the basis of an advantageous illustrative embodiment shown in the figures. However, the invention is not limited to this illustrative embodiment. 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 side view of a rotational device; 
         FIG. 2  is a bottom view of the rotational device according to  FIG. 1  in a rotated position; 
         FIG. 3  is a sectional view through a central area of the rotational device according to  FIG. 1 ; and 
         FIG. 4  is a sectional view through a side area of the rotational device according to  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A rotational device  10  is arranged in a vehicle (not shown here), in the present case in a utility vehicle, and supports a seat unit (not shown here). The seat unit and the rotational device  10  form a vehicle seat. The rotational device  10  is fastened, in the present case screwed, to a structure of the vehicle or to a podium-like console. In this case, the console is fastened to the floor of a passenger cell of the vehicle. 
     The arrangement of the vehicle seat and of the rotational device  10  inside the vehicle and the usual direction of travel x of the vehicle define the directional indicators used in the text below. A direction oriented perpendicularly with respect to the ground is designated below as the vertical direction, and a direction perpendicular to the vertical direction and perpendicular to the direction of travel x is designated below as the transverse direction. 
     The rotational device  10  has an approximately rectangular plate-like base component  20 . A front face of the base component  20 , situated to the front in the direction of travel, and lateral faces of the base component  20  are approximately rectilinear. A catch face  26  of the base component  20 , situated to the rear in the direction of travel x, is designed in the shape of an arc of a circle. By means of screws (not shown), the base component  20  is screwed onto the structure of the vehicle. 
     The rotational device  10  likewise has an approximately rectangular plate-like seat part support  30  of approximately the same size and shape as the base component  20 . The seat part support  30  is mounted on the base component  20  so as to be rotatable about a rotation axis S extending in the vertical direction. A front face of the seat part support  30 , situated to the front in the direction of travel x, and lateral faces of the seat part support  30  are approximately rectilinear. A rear face  36  of the seat part support  30 , situated to the rear in the direction of travel, is designed in the shape of an arc of a circle. By means of screws (not shown), the seat part support  30  is screwed onto the seat unit of the vehicle seat. 
     A geometric center point of the arc of the catch face  26  of the base component  20  lies on the rotation axis S. A geometric center point of the arc of the rear face  36  of the seat part support  30  likewise lies on the rotation axis S. When the rotational device  10  is located in the basic position, the seat part support  30  is oriented in the direction of travel x and the catch face  26  of the base component  20  is flush with the rear face  36  of the seat part support  30 . 
     A circular locking disk  40  is arranged in the vertical direction above the seat part support  30  and is rigidly connected to the base component  20 . The seat part support  30  thus lies, in the vertical direction, between the base component  20  and the locking disk  40 . 
     The base component  20  has a first through-opening  21 , which in the present case is designed as a circular bore. The seat part support  30  has a second through-opening  31 , which in the present case is designed as a circular bore. The locking disk  40  has a third through-opening  41 , which in the present case is designed as a circular bore. 
     The second through-opening  31  has a larger internal diameter than the first through-opening  21 . The third through-opening  41  has an internal diameter of approximately the same size as the first through-opening  21 . The rotation axis S extends centrally through the first through-opening  21 , the second through-opening  31  and the third through-opening  41 . 
     A locking mechanism (not shown here) is arranged on the seat part support  30  and comprises a two-armed locking lever, which is mounted rotatably about a locking axis arranged parallel to the rotation axis S. A projection is arranged on a first arm of the locking lever and, by means of a pretensioned draw spring engaged on the free end of the first arm, is loaded into a groove-shaped recess of the locking disk  40  with form-fit and force-fit engagement and, when engaged in the groove, locks the seat part support  30  is its momentary position of rotation. By acting manually on the free end of the second arm of the locking lever counter to the force of the draw spring, the projection is moved out of the groove and the locking of the seat part support  30  is canceled, as a result of which the seat part support  30  is rotatable relative to the base component about the rotation axis S. 
     A support ring  50  bears with a lower face on the base component  20  and passes through the second through-opening  31  coaxially with respect to the rotation axis S. The locking disk  40  bears on an upper face of the support ring  50 . The external diameter of the support ring  50  is larger than the internal diameter of the first through-opening  21  and larger than the internal diameter of the third through-opening  41 . The internal diameter of the support ring  50  is slightly smaller than the internal diameter of the first through-opening  21  and slightly smaller than the internal diameter of the third through-opening  41 . 
     On its lower face bearing on the base component  20 , the support ring  50  in the present case has a protruding annular shoulder which, for exact positioning of the support ring  50 , protrudes into the first through-opening  21  of the base component  20 . The support ring  50  can also have a protruding annular shoulder on its upper face bearing on the locking disk  40 , which annular shoulder, for exact positioning of the support ring  50 , protrudes into the third through-opening  41  of the locking disk  40 . 
     The locking disk  40  is fastened to the base component  20  by means of a plurality of bearing screws  42 , in the present case six bearing screws  42 . The bearing screws  42  extend through through-bores provided for them in the locking disk  40  and are screwed into threaded bores of the base component  20 . 
     The bearing screws  42  are arranged on a circumferential line of a circle whose center point lies on the rotation axis S, and they are distributed uniformly on the circumferential line of the circle. The bearing screws  42  are thus arranged at the same distance from the rotation axis S, this distance being greater that the outer radius of the support ring  50  but smaller than the inner radius of the second through-opening  31 . The bearing screws  42  are thus located radially between the support ring  50  and the seat part support  30  with respect to the rotation axis S. 
     A first roller bearing  61  is arranged in the vertical direction between the locking disk  40  and the seat part support  30 . The first roller bearing  61  extends circularly around the rotation axis S and is arranged, in the radial direction, at a first bearing distance  66  from the rotation axis S. 
     A second roller bearing  62  is arranged in the vertical direction between the seat part support  30  and the base component  20 . The second roller bearing  62  extends circularly around the rotation axis S and is arranged, in the radial direction, at a second bearing distance  67  from the rotation axis S. 
     A third roller bearing  63  is arranged in the vertical direction between the seat part support  30  and the base component  20 . The third roller bearing  63  extends circularly around the rotation axis S and is arranged, in the radial direction, at a third bearing distance  68  from the rotation axis S. 
     The second bearing distance  67  is greater than the first bearing distance  66 , which is greater than the third bearing distance  68 . The third bearing distance  68  is also greater than the inner radius of the second through-opening  31 . 
     By means of the roller bearings  61 ,  62 ,  63 , which in the present case are designed as ball bearings, the seat part support  30  is supported between the base component  20  and the locking disk  40  and is mounted rotatably about the rotation axis S relative to the base component  20  and to the locking disk  40 . For this purpose, the roller bearings  61 ,  62 ,  63  have suitable ball raceways and balls. 
     When the bearing screws  42  are screwed fast with a tightening torque, they exert a tightening force FS, which draws the locking disk  40  and the base component  20  toward each other and thus braces the locking disk  40  against the base component  20 . 
     On account of the tightening force FS of the bearing screws  42 , the locking plate  40  presses with a first bearing force F 1  on the first roller bearing  61 , which in turn presses with the first bearing force F 1  on the seat part support  30 . 
     The direction of action of the first bearing force F 1  depends on the configuration of the ball raceways of the first roller bearing  61 . In the present case, the first bearing force F 1  acts in the vertical direction. However, the first bearing force F 1  can also have a component in the vertical direction and a component in the radial direction with respect to the rotation axis S. 
     The seat part support  30  presses with a second bearing force F 2  on the second roller bearing  62  and with a third bearing force F 3  on the third roller bearing  63 . The second roller bearing  62  in turn presses with the second bearing force F 2  on the base component  20 , and the third roller bearing  63  in turn presses with the third bearing force F 3  on the base component  20 . 
     The directions of action of the second bearing force F 2  and of the third bearing force F 3  depend on the configurations of the ball raceways of the second roller bearing  62  and of the third roller bearing  63 . In the present case, the second bearing force F 2  and the third bearing force F 3  each act in the vertical direction. The second bearing force F 2  and the third bearing force F 3  can also each have a component in the vertical direction and a component in the radial direction with respect to the rotation axis S. 
     The ratio of the second bearing force F 2  to the third bearing force  63  can be chosen by suitable choice of the first bearing distance  66  in relation to the second bearing distance  67  and to the third bearing distance  68 . 
     In particular, the ratio of the vertically acting component of the second bearing force F 2  to the vertically acting component of the third bearing force F 3  can be chosen by suitable choice of the first bearing distance  66  in relation to the second bearing distance  67  and to the third bearing distance  68 . 
     By reducing the difference between the first bearing distance  66  and the second bearing distance  67 , while at the same time increasing the difference between the first bearing distance  66  and the third bearing distance  68 , the vertically acting component of the second bearing force F 2  is increased, and the vertically acting component of the third bearing force F 3  is reduced. By reducing the difference between the first bearing distance  66  and the third bearing distance  68 , while at the same time increasing the difference between the first bearing distance  66  and the second bearing distance  67 , the vertically acting component of the second bearing force F 2  is reduced, and the vertically acting component of the third bearing force F 3  is increased. 
     In the present case, the first bearing distance  66  is chosen in relation to the second bearing distance  67  and to the third bearing distance  68  in such a way that the vertically acting component of the second bearing force F 2  and also the vertically acting component of the third bearing force F 3  always have a sufficient magnitude. This avoids a situation where vibrations or oscillations acting on the rotational device  10  cause the seat part support  30  to be deflected in the vertical direction or to be bent in such a way that balls of the second roller bearing  62  or balls of the third roller bearing  63  lose contact with the seat part support  30  and/or the base plate  20 . 
     A catch hook  37  is mounted in a central area of the rear face  36  of the seat part support  30 . The catch hook  37  is U-shaped, with an upper limb of the catch hook  37  extending horizontally, bearing in the vertical direction on the seat part support  30  and being rigidly connected, in the present case screwed, onto the latter. Alternatively, the catch hook  37  can also be welded onto the seat part support  30 . 
     A base portion of the catch hook  37 , which is located behind the seat part support  30  in the direction of travel x, extends from the upper limb of the catch hook  37  downward in the vertical direction to a point below the base component  20 . In the basic position of the rotational device  10 , a lower limb of the catch hook  37  extends forward from the base portion of the catch hook  37  in the direction of travel and, parallel to the upper limb of the catch hook  37 , under the base component  20 . 
     Thus, in the vertical direction, the catch hook  37  engages around the base component  20  and the seat part support  30 . A slide element  38 , which in the present case is made of plastic, is mounted on the lower limb of the catch hook  37 , on the side facing toward the upper limb. When the rotational device  10  is located in the basic position, the slide element  38  is located in the vertical direction between the lower limb of the catch hook  37  and the base component  20  and bears on the base component  20 . 
     When the rotational device  10  is located in the basic position, the slide element  38  prevents the catch hook  37  from directly touching the base component  20 . In the event of vibrations or oscillations, this therefore avoids the creation of disturbing noise. 
     The catch hook  37  also constitutes a crash safeguard for the rotational device  10 , in particular in the event of a head-on collision. In the event of a crash, the catch hook  37  prevents the seat part support  30  and the base component  20  from being torn apart. 
     When the seat part support  30 , having been unlocked, is rotated from the basic position about the rotation axis S relative to the base component  20 , the catch hook  37  moves with the slide element  38  along the catch face  26  of the base component  20 . The catch hook  37  engages around the base component  20  as far as a rotation of in the present case approximately 30° from the basic position. Starting from a rotation of in this case more than 30° from the basic position, the catch hook  37  withdraws from the base component  20 . 
     The slide element  38  has beveled side faces. When the seat part support  30  is rotated back to the basic position from a position in which it has been rotated beyond 30°, the beveled side faces of the slide element  38  facilitate the insertion of the base component  20  into the catch hook  37 . 
     The features disclosed in the above description, in the claims and in the drawings may be of significance both individually and also in combination with one another for the implementation of the invention in the various embodiments thereof. 
     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.

Technology Classification (CPC): 5