PATENT ABSTRACT
A locking device for vehicle seats, in particular motor vehicle seats, includes two mutually displaceable parts. A rail, associated to one of the parts, extends in the direction of displacement and has at least one row of snap-in holes extending longitudinally along the rail. These holes are separated from each other by web-like material sections. Ratchets, associated to the other part, can move in relation to the rail between a disengaging position and a locking position. They move perpendicularly to the direction of extension of the rail, and are controlled via an operating mechanism. When the mutually displaceable parts are in locked position, at least one of the ratchets engages in a corresponding snap-in hole. At least one retaining element prevents involuntary disengaging of the ratchet from an effective locking position. As a result, reliable locking is achieved, in particular in the event of a crash, which entails high frequency vibrational fractions.

PATENT DESCRIPTION
FIELD OF THE INVENTION 
     The present invention relates to a locking arrangement for vehicle seats, particularly for motor-powered vehicle seats, having two parts which are displaceable relative to one another. A rail is associated with one of the parts. The rail extends in the direction of displacement and has at least one row of snap-in holes extending in rail longitudinal alignment. The holes are separated from one another by web-like material sections. Ratchets, associated with the other part, can be controlled in their movement relative to and transverse to the direction of the extension of the rail between a disengaging position and a locking position, and can be controlled by means of an operating mechanism. When in locking position, at least one of the parts displaceable relative to one another engages in an associated snap-in hole. 
     BACKGROUND OF THE INVENTION 
     A locking arrangement for vehicle seats is disclosed in PCT-WO 95/17317. With that locking arrangement, it is possible to displace two displaceable parts of the vehicle seat relative to one another continuously. A basically reliable locking is realized, even in the case of increased stress load. 
     In that locking arrangement, the ratchets have a wedge shape, as required by the obliquely arranged engagement surfaces. The inclined surfaces are pointed downward in an alignment transverse to the displacement alignment. A load in the direction of displacement, when the occasion arises consequently, has such low force components on the ratchets for producing a release of the locking that as a result generally no involuntary unlocking can occur. With a considerable unfavorable introduction of force, as, for example, can occur in the case of a crash with high frequency vibrational fractions, the ratchet in turn is raised out of its locked position, and thus, can be subject to a partial longitudinal thrust, lasting until the next ratchet can take over the load. 
     EP-A-0 786 37 discloses an arrangement for manual longitudinal adjustment of a vehicle seat. It includes a guide frame, a locking member displaceable vertically therein and a pivotal locking lever within an opening in the locking member. The locking member is provided at the bottom with a cog arrangement projecting downward through an opening in the guide frame and engaging with a corresponding cog arrangement. The guide frame is fastened to a top rail and serves as stop for two springs which act upon the locking member or the locking lever on the locking position. With this arrangement, it is possible only to bring ratchets in the sense of strips of cogs in or out of engagement with one another for the execution of a locking or unlocking setting. In the case of high frequency vibration fractions in the case of a crash, there exists the possibility of the breakdown of the locking. 
     SUMMARY OF THE INVENTION 
     Objects of the present invention are to provide an improved locking arrangement that prevents an undesired removal from engagement of the relevant locking ratchet by lifting it out of an effective locking position, especially in the case of a crash, leading to high frequency vibration fractions. 
     The foregoing objects are basically provided by a locking arrangement for vehicle seats having two relatively displaceable seat parts, comprising a rail associated with one seat part having a longitudinal axis extending in a displacement direction and having at least one row of snap-in openings arranged along the longitudinal axis. The snap-in openings are separated from one another by web-like material sections. Ratchets associated with the other seat part are displaceable transverse to the longitudinal axis relative to the rail between disengaging positions and locking positions in the snap-in openings. An operator is coupled to the ratchets for controlling movement of the ratchets between the disengaging positions and the locking positions. At least one retaining element is coupleable to each of the ratchets for preventing undesired disengagement of the respective ratchet from the locking position thereof. 
     The retaining prevents undesired removal from engagement of the relevant ratchet by lifting it out of an effective locking position. Effective locking is reliably in place even in case of a crash with high frequency vibration fractions, since the ratchets in the case of even minimal lifting up movement out of their locking position are either held tightly in an effective locking position or are subject to an additional retaining force in the direction of this locking position by spring latches or catching hooks. 
     Preferably, the relevant retaining element is formed of a sort of catch device, which works force-locking and/or form-locking on the associated ratchet. 
     With one especially preferred embodiment of the locking arrangement according to the present invention, the catch device is formed of a pair of spring latches which limit an engagement opening for the ratchet and which are arranged with their free spring ends in position for contact with the ratchet. On the basis of this arrangement, with minimal lifting displacement of the ratchet in the area of a still effective locking position, a counterforce is carried out by the adjustment force of the spring latches such that lifting up is prevented. 
     In another preferred type of embodiment, the catch device is formed of a catching hook which can be moved by the dovetail tenon part of the operating mechanism and controlled by a compression spring between a detached or disengaging position and a locking position. In the locking position, the ratchet is blocked in a reliably effective locking position. A form-locking connection is instituted, with especially high retaining forces which can be executed on the locking ratchet in the objective of a blocking and providing a still effective locking position. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure: 
     FIG. 1 is a front elevational view of a locking arrangement according to a first embodiment of the present invention; 
     FIG. 2 is a top plan view of a section of the rail of the locking arrangement of FIG. 1; 
     FIGS. 3,  4 ,  5  are side elevational, perspective and top plan views, respectively, of the locking arrangement of FIG. 1; 
     FIG. 6 is a side elevational view in section taken along line VI—VI of FIG. 5; 
     FIG. 7 is an exploded perspective view of the locking arrangement of FIGS. 3 to  5 ; 
     FIG. 8 is a side elevational view of the retaining element of the locking arrangement of FIGS. 3-5; 
     FIGS. 9 a-d  are perspective, perspective, front and side elevational views, respectively, of a retaining element according to a second embodiment of the present invention; and 
     FIG. 10 is a front elevational view, partially in section, of a locking arrangement according to the second embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows the locking arrangement of the present invention for vehicle seats, especially for motor-powered vehicle seats. The locking arrangement has two movable parts which are displaceable to one another. A rail  10  is associated with the one part and extends in the alignment of displaceability. The rail has a row of snap-in holes  12  (see FIG. 2) extending in rail longitudinal alignment or axis and separated from one another by web-like material sections  14 . Ratchets  16  are associated with the other rail-like part of identical configuration, and can be controlled for movement transverse to the direction of extension of rail  10 . The ratchets are displaced relative to that rail between a disengaging position and a locking position, and are also controllable by means of an operating mechanism  18 . At least two of the parts displaceable relative to one another in the locking position engage, as shown in FIG. 1, in a snap-in opening  12 , which is located on the locking position of the locking arrangement. For engagement with the associated snap-in hole  12 , ratchets  16  have engagement surfaces  20 , which because they are oblique form a wedge shape for the relevant ratchet  16 . 
     The locking arrangement also includes retaining elements which prevent the execution of undesired removal of engagement of the relevant ratchet  16  from an effective locking position. The retaining element in this case is formed of a catch device  22  (FIGS. 3,  8 ,  9 ), which executes the force- and/or form-locking on the associated ratchet  16 . According to the first embodiment of the locking arrangement to be described, catch device  22  is formed of a pair of spring latches  24  (FIG.  8 ). Spring latches  24  limit an engagement opening  26  for ratchet  16  and are embodied with their free spring ends arranged for contact with the ratchet. In the case of high stress loads, especially in the case of a crash with high frequency vibration fractions, when a displacement of ratchet  16  is generated in the direction of its disengaging position, a counterforce is exerted on the ratchet. The counterforce is in the direction of its effective locking position. 
     In another embodiment of the locking arrangement according to the illustration shown in FIGS. 9 a  and  9   d , each catch element  22  is formed of a catching hook  30  which can be displaced between a release or disengaging position and a locking or engaged position. Displacement is controlled by the dovetail tenon part of the operating mechanism and a compression spring, in which ratchet  16  is blocked in a still effective locking position. The blocking can be released without further problem as explained in greater detail hereinafter. 
     Individual ratchets  16  are guided with axial spacing from one another in guides  32  of housing  34  (FIG.  7 ). Guides  32  extend transverse to the rail longitudinal alignment or axis. Ratchets  16  are held by means of a biased spring in the form of a compressing sprig  36  in the alignment of locking positions. Compressing spring  36  is supported with one end on the sheet metal cover  38  of housing  34  and with its other end on ratchet  16  or on parts of catch device  22  according to the representation as in FIGS. 9 a-d . As shown especially in FIGS. 7 and 8, the pair of spring latches  24  is part of sheet metal cover  38  and connected as one integral piece with this cover. For control of ratchets  16 , on their side turned toward operating mechanism  18  (FIG.  1 ), these ratchets in turn have a control cam  40  controlled by the projecting dovetail tenon part  42  of a control rod  44  of operating mechanism  18 . 
     Sheet metal cover  38  can be manufactured by cutting out or stamping out a flat section of sheet metal. The exterior contour of sheet metal cover  38  can be executed by corresponding bending and rolling. On its side facing ratchets  16 , sheet metal cover  38  has retaining hooks  46  (FIG. 4) in pairs diametrically facing one another. Their hook-shaped projections construct a contact surface for the one free end of the relevant compression spring  36 . Sheet metal cover  38 , on its side opposite the pairs of spring latches  24 , has notches  48  (FIG. 7) which serve for the penetration of stationary housing part webs  50 . This construction simplifies the tightening down of sheet metal cover  38  on the housing  34  associated with it. 
     One-piece latch-like projections  52  are fastened to the bottom of the essentially U-shaped sheet metal cover  38 . The projections  52  are of identical lengths, are bent toward one another in pairs, as is shown particularly in FIG. 8, and limit the engagement openings  26  for control cams  40  of a ratchet  16 . They are simply bent or curved inward in the same sense as retaining hooks  46 . Spring ends  28  of a pair of spring latches  24  can thus, when not in operational state, engaged force-locking on one another or, as shown in FIG. 8, with tapering of engagement opening  26 , can limit a penetration gap  54 . 
     In the representations shown in the drawings, all ratchets  16  are found in their locking position locking the rail  10 , except for ratchet  16  furthest to the right when viewing the drawings, which is shown in its unlocking, disengaging position. On its top, housing  34  is mounted essentially flush with sheet metal cover  38  mounted along its midline. Housing  34  seen in its longitudinal alignment, in other words in the alignment of the free ends of ratchets  16 , has conically tapering side parts  56  tapering downward (FIG.  6 ). Side parts  56  are provided with boreholes  58  for the penetration of two screws  60  tightening the mounting of housing  34  on the slide rail. 
     The details of the construction of the individual ratchets  16  can be seen especially from the representation of FIGS. 9 a-d . The contact surfaces  20  of the relevant ratchet  16  are arranged opposite one another. At their free lower ends, they limit a flat closing-off surface  62 . Opposite this closing-off surface  62 , ratchet  16  has a contact surface  64 . In the first embodiment and contrary that that shown in FIGS. 9 a-d , contact surface  64  extends parallel and in that same direction and in alignment with closing-off surface  62 . Control cam  40  is attached in the extension of contact surface  64  and engages therewith at least on one side. Control cam  40  and the engagement surface  20  associated therewith define a U-shaped contact space  66  therebetween. With ratchets  16  inserted in housing  34 , space  66  is penetrated by a transverse web surface  68  (FIGS. 3 and 10) of housing  34  extending in rail longitudinal alignment. 
     As further support in the guiding for the displacement of the relevant ratchet  16  in housing  34 , this housing has an auxiliary web surface  70  (FIG.  3 ). Web surface  70  at least partially leads to the point provided for a widening of ratchet  16 , and provides guide surfaces for the engagement in the associated guide notch openings within housing  34 , which notch openings form web-like, widened-out notches within guides  32 . The relevant auxiliary web surface  70  of each ratchet  16  can also be manufactured as a sort of an embossing, so that a corresponding channel guide  72  is produced opposite, and extends within ratchet  16 . 
     As is shown especially in FIG.  3  and in connection with FIG. 1, between control cams  40  and the associated top of transverse web surface  68  of housing  34 , a recessed space extends in which the associated dovetail tenon part  42  of operating mechanism  18  can engage. If articulated rod  74  is controlled manually or by a corresponding drive, pivoting it around the fastened-on axle guide  76  and consequently around rotary axis  78 , the relevant dovetail tenon part  42  lifts the associated ratchet  16  on control cam  40 . This ratchet is then displaced counter to the spring bias of compressing spring  36  into its disengaging position and consequently into alignment with the interior of housing  34 . If articulated rod  74  is left free, compression springs  36  assist with the corresponding retaining movement holding the ratchet in the original position and consequently with the overall arrangement in the locking position. In the locking position, the engagement surfaces  20  of ratchets  16  project downward out of housing  34 , and can engage in the associated snap-in holes or openings  12  of rail  10 . With corresponding guiding, the ratchets can undertake the locking without any play. 
     In the described displacement of ratchets  16  counter to the force of compression springs  36 , control cams  40  are moved through engagement openings  26  of associated spring latch pairs  24 . The continued movement of control cam  40  causes it to come in contact with spring ends  28  and forces these spring ends apart while remaining in axial alignment. Penetration gap  54  is widened, and the two spring ends  28  then press force-locking on control cam  40 . If the aforementioned operating mechanism  18  is constructed of a plurality of parts or is multi-sectional, and for example has individually controllable dovetail tenon parts controlling the relevant control cam  40 , individual control of ratchets  16  can also be attained. 
     In another embodiment of the locking arrangement of the present invention, as shown in FIGS. 9 a  to  9   d , spring latch pairs  24  as retaining element as well as catch device  22  can be deleted. Moreover, in this case, catch device  22  made up of a catching hook  30  can be moved into a locking position by dovetail tenon part  42  of the operating mechanism and a compressing spring  36  controlled between a released position, as it is shown in FIGS. 9 a-d , into a locking position. While in the locking position, ratchet  16  is blocked in a still effective locking position. For this purpose, the relevant ratchet  16  includes the aforementioned channel guide  72  receiving catching hook  30 . By means of a base plate  80 , hook  30  cooperates with a control hook  82  (FIG.  10 ), which moves catching hook  30  in the described manner controlled by dovetail tenon part  42  of operating mechanism  18  and a compression spring  36 . 
     An inclined contact surface  64  is required in this case for contacting base plate  80  with ratchet  16 . They meet together in an imaginary extension with the horizontally arranged closing-off surface  62  likewise in an imaginary extension in a cross sectional line. Base plate  80  can include projections  84  for the incorporation or enveloping of contact surface  64 . On the opposite side, base plate  80  is arranged in a deflection or reorientation set off at 90° in a flat articulating plate  86 . Catching hook  30  as well as control hook  82  are shaped in turn out of articulating plate  86 . Preferably, control hook  82  stretches over or beyond the bottom of control cam  40  and engages through engagement space  66  in that manner. 
     FIGS. 9 c  and  9   d  show the ratchet during the locking procedure. Dovetail tenon part  42  of operating mechanism  18  in this case presses the hooked end of control hook  82 , while surmounting the spring force of compression spring  36  against control cam  40 . Thus, the hook part of catching hook  30  is brought out of engagement and ratchet  16  can be raised. 
     FIG. 10 shows a ratchet  16  with catching hook  30  in locked state. The hook of catching hook  30  is brought into locking position by compression spring  36  (base plate  80  comes into contact surface  64 ). When ratchet  16  now comes under extreme stress, to lift it up (under control), the hook of catching hook  30  comes into contact under a projection in the area of the housing bottom edge. Thus, ratchet  16  is then held tightly in an effective locking position. 
     With the catch device according to the present invention as retaining element, which causes force- and/or form-locking on the associated ratchet, consequently an undesired removal from engagement of the relevant ratchet by moving it out of an effective locking position is prevented. In good order, the catch device sustains the relevant ratchet and holds it in a still effective locking position. 
     A reliable locking takes place in case of a crash with high frequency vibration fractions, since the ratchets undergoing even minimal lifting up movement out of their locking position are captured. In such a manner, they can still mesh, whereby an additional holding force can be exerted simultaneously in the direction of this blocking position by means of the catch mechanism. A locking catch procedure is facilitated independent of the relevant engagement situation. As a consequence of the degree of engagement of the relevant ratchet or locking mechanism, undesired displacement of the ratchet is also prevented, when this mechanism as compared to the state of the art has not completely attained its blocking end position. 
     While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.