Abstract:
An adjustment device for adjusting seats includes a rotatable drive element, a rotatable output element, a first clamping element freewheel that blocks the output element continuously in different positions in both adjustment directions and that is released by a release element and a second clamping element freewheel that is coupled via the release element to the first clamping element freewheel, blocks the output element continuously in different positions in both adjustment directions and is released by an actuating element. The drive element is pre-tensioned in a middle position via two springs acting in different directions and the two springs pre-tension the actuating element in a middle position.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
     The invention described and claimed hereinbelow is also described in German Patent Application 10 2014 103 989.0, filed on Mar. 24, 2014. The European Patent Application, the subject matters of which is incorporated herein by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The present invention relates an adjustment device, for example, for adjusting seats. 
     EP 979 179 discloses a seat adjuster, in which a brake is provided between a fixed part and an adjustable part, to be able to block the two parts continuously in both adjustment directions. The brake can be released via a release element, to then be adjusted in one of the two directions using an adjustment body. An additional locking unit, which acts step-by-step, latches to lock the blocked position. Such latching is perceived to be annoying by the user, since, on the one hand, latching noises occur and on the other hand, latching cannot take place in intermediate positions. In addition, numerous parts are required for the pre-tensioning of the latch, which makes the installation complex. 
     WO 2012/013234 discloses an adjustment mechanism in which two clamping locks connected in series are provided, where each implements a freewheel brake. The two clamping locks comprise clamping elements, which enable continuous adjustment and blocking in both adjustment directions. The two clamping locks are coupled to one another in this case via a disengagement element, so that after the blocking of an output element by the first clamping lock, the second clamping lock can be switched into a freewheel position, to move an actuating lever back into a starting position. In this case, the actuating lever is pre-tensioned via a first lock spring in a starting position and the disengagement element is pre-tensioned via a second lock spring in a starting position. The two lock springs are arranged in series in the axial direction of the output shaft, so that a relatively large amount of construction space is required in the axial direction. In addition, the problem exists that one lock spring acts on the triggering element and the other lock spring acts on the lever adapter. The reset takes place relatively imprecisely due to tolerances and play. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the shortcomings of known arts, such as those mentioned above. 
     To that end, the present invention provides an adjustment device, which has a compact structure and enables a precise adjustment of a drive element in relation to an output element. 
     According to an embodiment of the invention, the adjustment device comprises a first clamping element freewheel and a second clamping element freewheel, by each of which one output element is blocked and released continuously in different positions in both adjustment directions. A release element is provided to release the first clamping element freewheel and an actuating element is provided to release the second clamping element freewheel. The drive element is pre-tensioned in a middle position in this case via two springs acting in different directions. The two springs also pre-tension the actuating element in a middle position. Thus, independently of the rotational direction of the drive element, one of the two springs is used for the reset into a starting position, i.e., a middle position. The respective other spring is used to reset the actuating element into a middle position, so that depending on the rotational direction of a spring, either the drive element or the actuating element is pre-tensioned in a middle position. A more compact structure thus results and the production of the adjustment device with only a few parts is enabled. The pre-tension of the actuating element is implemented essentially without play in this case, since the actuating element is directly moved and is pre-tensioned in a middle position during a movement of the drive element. 
     The first and the second clamping element freewheels can be implemented in each case as a clamping lock, in which clamping elements are provided between an outer ring and an inner ring, enabling continuous blocking in both adjustment directions. Like clamping locks are described in detail, for example, in WO 2012/013234 and are referred to hereafter as a clamping element freewheel, since a freewheel also can be achieved in addition to the blocking function. 
     Preferably, during a movement of the drive element in a first rotational direction, the drive element is pre-tensioned by a first of the two springs in the middle position and the actuating element is pre-tensioned by the other, second spring in the middle position. In contrast, if the drive element is moved in a second rotational direction, which is opposite to the first rotational direction, the drive element is pre-tensioned by the second spring in the middle position and the actuating element is pre-tensioned by the first spring in the middle position. Thus, depending on the rotational direction, the drive element and the actuating element can be pre-tensioned by the first spring or the second spring. 
     For a compact structure of the adjustment device and easy installation, the springs can be implemented as coiled springs. The springs are preferably held in a curve in a receptacle of a housing. In the middle position of the drive element and the actuating element, the springs are held with their end sides on a stop. In this case, a projection of the drive element is arranged between the end sides of the springs and a projection of the actuating element is arranged between two opposing end sides of the springs. Thus, with rotationally-fixed fixation of the actuating element on the drive element, an adjustment and blocking operation, which is essentially without play, is caused via the first and second clamping body freewheels. 
     In an embodiment of the invention, the output element has an axle and the drive element has a ring arranged around the axle. The ring forms a part of the second clamping body freewheel in this case, so that the drive part acts directly via the ring on the second clamping body freewheel, to reduce the number of parts. Of course, it also is possible to implement the drive element as the axle and the output element as the ring, to provide an adjustment device according to the invention. 
     The springs arranged in the curved receptacles on the housing are installed from a first side in the receptacles. Furthermore, at least one slot is provided on the curved receptacles, through which a projection is guided, which presses against an end side of the springs. The actuating element and the drive element are thus installed compactly inside the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the invention will become apparent from the description of embodiments that follows, with reference to the attached figures, wherein: 
         FIG. 1  presents a view of a seat having an adjustment device according to the invention; 
         FIG. 2  presents a perspective view of the adjustment device according to the invention; 
         FIG. 3  presents a perspective exploded illustration of the adjustment device of  FIG. 2 ; 
         FIG. 4  presents a top view of a first clamping element freewheel of the adjustment device of  FIG. 2 ; 
         FIG. 5  presents a view of the first clamping body freewheel of  FIG. 4  with a release element; 
         FIG. 6  presents a top view of a second clamping body freewheel of the adjustment device; 
         FIG. 7  presents a view of the second clamping element freewheel with an actuating element; 
         FIG. 8  presents a perspective exploded illustration of a housing of the adjustment device; 
         FIG. 9  presents a view of the housing of the adjustment device with the springs, and 
         FIG. 10  presents a perspective view of the housing with the springs during the installation. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a detailed description of example embodiments of the invention depicted in the accompanying drawings. The example embodiments are presented in such detail as to clearly communicate the invention and are designed to make such embodiments obvious to a person of ordinary skill in the art. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention, as defined by the appended claims. 
     A vehicle seat  1  is shown in  FIG. 1  to comprise a seat body  2 , on which a backrest  3  is mounted to be pivotable. The seat body  2  is supported on a framework  4 , wherein the seat body  2  is held on the framework  4  via two parallel levers  5 . An adjustment device  6 , including a drive lever  7  that is rotatable about a horizontal axis in both directions, is installed on the seat body  2 . If the drive lever  7  is pivoted upward into a position  7 A, pivoting of the lever  5  clockwise can be initiated via the adjustment device  6 , whereby the seat surface  2  is lowered. If the drive lever  7  is pivoted downward into position  7 B, rotating of the lever  5  counterclockwise is caused via the gearing, so that the seat body  2  is raised. 
     In  FIGS. 2 and 3 , the adjustment device  6  is shown. The adjustment device  6  comprises a housing  80 , which has a flange  8  with openings  9  on opposing sides, to fix the housing  80  on the seat body  2 . The housing  80  is closed on the upper side by a cover  50 , which is implemented as plate-shaped and has webs  52 , which engage between projections  55  of the housing. The housing  80  and the cover  50  are penetrated by an axle  17 . 
     As shown in  FIG. 3 , the axle  17  has a smooth-walled section and a middle section having radially protruding wedges  19 , which are used for the rotationally-fixed fixation of an inner ring  12  of a first clamping body freewheel  10 . Furthermore, a protruding pinion  18  is provided on the axle  17 , which is engaged with a gearing, in particular a toothed rocker, which is implemented on a lever  5  or a part connected to the lever  5 , to be able to perform a vertical adjustment of the seat body  2  via the pinion  18 . 
     The first clamping element freewheel  10  comprises cylindrical clamping elements  13  and  13 ′, which press against a cylindrical internal surface of an outer ring  11 . Furthermore, the clamping bodies  13  and  13 ′ press against the inner ring  12 , which has a round contour, and has a flattening  14  in each case in the region of the clamping elements  13  and  13 ′. A block  45  made of an elastic material is inserted between the clamping elements  13  and  13 ′. The inner ring  12  can be blocked and released in both directions in relation to the outer ring  11  via the clamping elements  13  and  13 ′. 
     In a starting position, inner ring  12  and outer ring  11  are blocked in relation to one another, since in each case one of the clamping elements  13  and  13 ′ causes a blocking in one direction. If the clamping element  13  is moved slightly by a release element  70  having projections  71  in a circumferential direction, the release is achieved and the blocking is canceled. The inner ring  12  can then be rotated in relation to the outer ring  11  in a first rotational direction. If the release element  70  having the projections  71  is moved in the opposite direction and the clamping element  13 ′ is shifted, a movement of the inner ring  12  in relation to the outer ring  11  in the opposite direction is released. 
     The outer ring  11  is connected rotationally-fixed in this case to a housing lower part, which is implemented as plate-shaped and has outwardly protruding webs  15 . Upwardly protruding sleeves  16  are provided on the webs  15 , which engage in the openings  9  of the housing  80 , so that housing lower part and housing  80  are fixed in a rotationally-fixed manner on one another. 
     The adjustment device  6  according to the invention furthermore comprises a second damping element freewheel  20 , which is released via an actuating element  40 . The second clamping element freewheel  20  comprises in this case an outer ring  30 , which has two radially protruding projections  31  having openings  32 , on which the drive lever  7  is fixed. 
     The first clamping element freewheel  10  and the second clamping element freewheel  20  are arranged inside the housing  80 , which is closed using the cover  50 . The cover  50  has an internal opening  51  for leading through one end of the axle  17 . Furthermore, recesses  53  are provided between the webs  52 , in which the projections  55 , which protrude from a support surface  54 , engage. 
       FIG. 4  shows the first clamping element freewheel  10  in a top view. The inner ring  12  comprises a nonround contour having flattenings  14 , at each of which a pair made of a clamping element  13  and a clamping element  13 ′ is provided. An elastic block  45  is arranged between the clamping elements  13  and  13 ′ of a pair. Between two clamping elements  13  and  13 ′, at which no elastic body  45  is provided, i.e., between two adjacent pairs of clamping elements  13 ,  13 ′, a projection  71  of a release element  70  engages in each case, wherein the release element  70  is implemented as essentially ring-shaped and is connected on the inner side in a rotationally-fixed manner to the axle  17 . The projections  71  are bent over and engage essentially in a formfitting manner or with little play between the clamping elements  13  and  13 ′, as shown in  FIG. 5 . 
     The second clamping element freewheel  20  is shown in  FIG. 6 . The clamping element freewheel  20  comprises an inner ring  21 , which has receptacles for the wedges  19  of the axle  17  on the inner side and is therefore connected in a rotationally-fixed manner to the axle  17 . The inner ring  21  is implemented as cylindrical on the outer circumference and presses against clamping elements  22  and  22 ′. An outer ring  30  is provided around the clamping elements  22  and  22 ′, which implements a cross section deviating from the cylindrical body, to jam the clamping elements  22  and  22 ′ in opposite directions. An elastic block  23  is provided between the clamping elements  22  and  22 ′. In a starting position, the inner ring  21  is blocked in relation to the ring  30  in opposite directions, wherein a release of the blocking occurs when in each case one of the clamping elements  22  or  22 ′ is shifted against the force of the elastic block  23 , so that then the ring  30  can be rotated in relation to the inner ring  21  in one direction. The function of the second clamping element freewheel  20  is therefore similar to the first clamping element freewheel  10 . In the second clamping element freewheel  20 , the outer ring  30  is coupled to the drive lever  7  via the projections  31 . 
     In  FIG. 7 , an essentially disk-shaped actuating element  40  is placed on the second clamping element freewheel  20 . The actuating element  40  is ring-shaped and comprises projections  41  protruding perpendicularly downward, which engage between two clamping elements  22  and  22 ′, to displace one of the clamping elements  22  or  22 ′ depending on the rotational direction and thus achieve a release. Furthermore, the actuating element  40  is provided with an internal cylindrical opening  43 , through which the axle  17  is guided. A protruding web  42  is implemented on one side of the actuating element  40 , which engages between two springs  60  and  61 , as will be explained hereafter. 
       FIG. 8  shows the housing  80  with the two springs  60  and  61 . The springs  60  and  61  are implemented as coiled springs and are arranged essentially in a semicircle inside the housing  80 . The springs  60  and  61 , which are compression springs, and are each held in a curve in a receptacle, wherein one end side of the springs  60  and  61  is supported in each case on a first stop  62  or an opposing stop  65 . A slot  63  is provided on the stop  62  and a slot  64  is provided on the stop  65 . The actuating element  40  engages with the projection  42  in the slot  64 . On the opposite side, a projection  33  on the ring  30  engages in the slot  63 . During the rotation of the ring  30 , firstly the second clamping element freewheel  20  is unlocked and then moves, via the clamping element  22  or  22 ′, the actuating element  40 , which is moved via the projections  41  with the clamping elements  22  and  22 ′. The projection  42  thus also moves in the rotational direction of the ring  30  against the force of one of the springs  60  or  61 . 
       FIG. 9  shows the housing  80  with the springs  60  and  61 , which are held in curved receptacles. The stops  62  and  65  also can be seen, on each of which a slot  63  or  64  is implemented. The springs  60  and  61  are arranged essentially in a plane perpendicular to the longitudinal direction of the axle  17 , the springs  60  and  61  at least overlap in this plane, so that a more compact structure is obtained. 
       FIG. 10  shows the housing  80  in an exploded illustration. The housing  80  comprises curved receptacles  66  and  67 , in each of which a spring  60  or  61 , respectively, is received. As  FIG. 10  shows, the slot  64  is not only located in the region of the stop  65 , but rather also extends as the slot  68  into the receptacle  66  and the receptacle  67 . The actuating element  40  can thus be moved from a middle position, in which the projection  42  is arranged in the region of the stop  65 , in both rotational directions along the slot  68 . On the opposite side, the slot  63  is provided on the stop  62 , which extends on opposite sides as the slot  69 . The projection  33  of the ring  30  is thereby rotated out of the middle position against the force of the springs  60  or  61  in opposite directions. 
     In the event of a movement of the drive lever  7  downward from a middle position, an adjustment operation is initiated, in that the output element is rotated using the pinion  18 . If the drive lever  7  is then let loose, one of the springs  60  or  61  causes a reset into the blocked position, so that a manual adjustment operation of the seat body  2  may be carried out. Vice versa, the drive lever  7  is then moved upward out of the middle position, to cause an adjustment of the seat body upward, wherein then the pinion  18  is blocked in the adjusted position and the drive lever  7  is pivoted back into its middle position by the force of one of the springs  60  or  61 . 
     LIST OF REFERENCE NUMERALS 
     
         
           1  seat 
           2  seat body 
           3  backrest 
           4  framework 
           5  lever 
           6  adjustment device 
           7  drive lever 
           7 A position 
           7 B position 
           8  flange 
           9  opening 
           10  clamping element freewheel 
           11  outer ring 
           12  inner rings 
           13 ,  13 ′ clamping elements 
           14  flattening 
           15  web 
           16  sleeve 
           17  axle 
           18  pinion 
           19  wedge 
           20  clamping element freewheel 
           21  inner ring 
           22 ,  22 ′ clamping elements 
           23  block 
           30  outer ring 
           31  projection 
           32  opening 
           33  projection 
           40  actuating element 
           41  projection 
           42  web/projection 
           43  opening 
           45  block 
           50  cover 
           51  opening 
           52  web 
           53  recess 
           54  support surface 
           55  projection 
           60  spring 
           61  spring 
           62  stop 
           63  slot 
           64  slot 
           65  stop 
           66  receptacle 
           67  receptacle 
           68  slot 
           69  slot 
           70  release element 
           71  projection 
           80  housing 
       
    
     As will be evident to persons skilled in the art, the foregoing detailed description and figures are presented as examples of the invention, and that variations are contemplated that do not depart from the fair scope of the teachings and descriptions set forth in this disclosure. The foregoing is not intended to limit what has been invented, except to the extent that the following claims so limit that.