Abstract:
A locking device of a longitudinal adjustment device of a vehicle seat is provided with a catch bar with periodically arranged snap openings and snap studs that is assigned to a bottom rail of the longitudinal adjustment device and is further provided with a locking unit assigned to a seat rail of the longitudinal adjustment device. The locking device has at least two licking pins that can be inserted into the snap openings independent of one another, they can be disengaged only jointly. The locking pins are arranged in a guide member which has a pin bore for each locking pin. The guide member is provided with an area facing the catch bar. Projections projecting toward the catch bar are arranged on this area and extend as a continuation of the pin bore.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to a locking device of a longitudinal, i.e. lengthwise adjustment device of a vehicle seat. The locking device is provided, on the one side, with a catch bar having periodically alternating snap openings and snap studs. The catch bar is assigned to a bottom rail of the longitudinal adjustment device. On the other side, the locking device is provided with a locking unit assigned to a seat rail of the longitudinal adjustment device. The locking unit has at least two locking pins that can be inserted into snap openings independent of one another and can jointly be retracted therefrom. The locking pins are arranged in a guide member having a pin bore for each locking pin.  
         DESCRIPTION OF PRIOR ART  
         [0002]    Such a locking device has been previously proposed in DE 197 09 149 A. Further relevant prior art is also described in EP 498 932 B and DE 27 29 770 C. This type of locking devices is also termed multiple pin locking device. These devices permit a fine pitched and sensitive longitudinal adjustment. In the locked permit a fine pitched and sensitive longitudinal adjustment. In the locked position, a locking pin fits beside a snap stud. Usually, it is a sloping side of the locking pin that fits beside a snap stud. The sloping sides are formed by truncated regions on the free end of the locking pins for example. A locking pins locks in one direction of displacement. Another locking pin locks in the other direction of displacement.  
           [0003]    Since generally but one locking pin is responsible for locking one direction of displacement, under crash load all of the locking forces act onto that one locking pin and onto the corresponding snap stud on which the locking pin is resting. Under high load conditions, the corresponding forces intentionally cause the locking pin to bend, as has already been described in DE 197 09 149 A mentioned herein above. Now, if a locking pin bends, the angle between the locking flank thereof and the snap stud changes. The angle increases. Before, it was within the range of self-locking, but after bending, it may be outside of this range. If it is outside of this range, said forces exerted onto the locking pin can push the locking pin upward, meaning out of the locking condition. The locking pin must however be prevented from disengaging from the corresponding snap stud in order not to release the locking state.  
         SUMMARY OF THE INVENTION  
         [0004]    This is where the invention comes to bear. The object of the invention is to further develop the locking device of the type mentioned herein above in such a manner that the locking pins are prevented from being pushed upward out of a locking position in an accident situation.  
           [0005]    In view of the locking device of the type mentioned herein above, the solution to this object is to provide the guide member with an area facing the catch bar, to arrange projections projecting toward the catch bar on said area and to have the projections extending as a continuation of the pin bores.  
           [0006]    The guide member thus has a projection protruding downward toward the catch bar for at least one of the pin bores, preferably for each pin bore. The projections extend as a continuation of the respective one of the pin bores.  
           [0007]    The projections are preferably annular. In any case, the projections allow for softer and more flexible guidance of the locking pins than in the region of the pin bore of the guide member. That is to say that they offer less resistance than the guide member to a locking pin bending laterally outwards. Under crash load, the projections are bent as well. They may more specifically warp, interlock and be brought into clutched engagement with the locking pin. As a result thereof, the locking pins are prevented from being pushed out of their locking position in an accident situation.  
           [0008]    Thanks to the invention the guide member may be made of steel. In current state of the art devices, the guide members are mainly made of aluminium. The length of the guidance in the current state of the art devices is much greater than in the device of the invention. In the above mentioned DE 197 09 149 A for example, the length of the guidance is relatively great, greater than 8 mm for example. The material of preference used for the guide member of the invention has a thickness ranging from about 3 to 4 mm, and is generally comprised between 2 and 5 mm. The projection considerably increases the length of the pin bore by preferably 20 to 120%.  
           [0009]    At least one locking pin, more specifically all of the locking pins, are preferably provided with a groove which is located in proximity to the corresponding pin bore, more specifically to the projection. The groove is also termed a crash groove. In the region of said crash groove, the locking pin is slightly tapered, e.g., by between 5 and 15%, preferably by about 8%. Moreover, toward the free end of the locking pin, the crash groove preferably has a sharp-edged transition to the intact cylindrical sheath where it more specifically forms a stop face.  
           [0010]    The above mentioned DE 197 07 149 A teaches to provide recesses such as blind bores, indentations and so on it front of and behind the pin bores in the guide member. Plastic deformation of the guide member in its lower portion is thus facilitated. But it describes no projections protruding downward from a lower face of the guide member. Furthermore, no crash groove capable of engaging with a projection is described.  
           [0011]    In an improved embodiment of the invention it is suggested to configure the projections to form rimmed holes. For this purposes, one pilot hole for each pin bore is first made in the guide member, said pilot hole having a diameter which is considerably smaller that that of the completed pin bore and amounts to 60% of the diameter of the completed pin bore for example. Now, the pilot hole is enlarged by means of a punch the outer dimensions of which correspond to the pin bore, a respective projection being formed in the process. The projections are connected to, and integral with, the guide member. In another embodiment, the projections may be realized by separately inserting a material, such as slide bushes for example.  
           [0012]    It proved particularly advantageous to provide a bead in the catch bar, said bead being curved upward toward the guide member. As a result thereof, the catch bar is mechanically reinforced and the stability of a lockin gcondition increased. The bead may comprise any cross section, such as semi-circular, triangular or trapezoidal.  
           [0013]    In a particularly preferred embodiment, the groove is realized by a plurality of individual groves. Three almost evenly spaced individual grooves may for example be provided side by side. The at least one groove and the individual grooves preferably have a truncated bottom that tapers toward the free end of the locking pin. A stop face is preferably configured on the end of each groove, or of each individual groove, said stop face pointing toward the free end of the locking member. At their free ends, the locking pins advantageously have a short, cylindrical front end.  
           [0014]    The fluting formed by several individual grooves efficiently prevents the locking pin from being pushed upward out of its locking position in an impulse-like or in a slow manner. As soon as the locking pin is slightly bent in the event of an accident, the several individual groves provide many possibilities for interlocked and clutched engagement. Several individual grooves that may interact with the material of the guide member at the lower end of the pin bore are available so that the locking pin is prevented from moving upward.  
           [0015]    The fluting also slightly weakens locally the locking pins so that theses preferably warp in the region of the fluting. This is where the locking pins also offer the largest area for abutment on the region about the lower end of the pin bore.  
           [0016]    The reduction in the diameter of the locking pins in the region of the fluting is chosen, on the one side, to be great enough, so that the stop face provided is great enough to provide a good mechanical interlock and, on the other side, is chosen not so great that the locking pin is markedly weakened and risks to beak in the region of the fluting in the event of an accident. What is wanted is a selective deformation in the region of the fluting.  
           [0017]    To configure the crash groove in the form of several individual grooves arranged side by side provides the advantage that, under load, the locking pins are better brought into interlocked and clutched engagement with the projections in the region thereof. As a result thereof, dynamic effects caused by the pin bouncing up under crash load are reduced.  
           [0018]    It finally proved advantageous to configure the locking pins to have a round shape, but the pin bores to have a non round shape. This more specifically applies to the region of the projections. Under a defined load, the projections may plastically deform. As a result thereof, the edges of the grooves, or of the individual grooves, are allowed to better engage into the projection.  
           [0019]    Further advantages and characteristics of the invention will become apparent in the other claims and in the following non restrictive description of embodiments given by way of example only with reference to the drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a perspective assembly drawing of a longitudinal guide with seat rail and bottom rail, a locking unit with four locking pins and one guide member being allocated thereto,  
         [0021]    [0021]FIG. 2 is a rear side of the arrangement depicted in FIG. 1, viewed in the direction indicated by the arrow II in FIG. 1, this time in the assembled and engaged condition,  
         [0022]    [0022]FIG. 3 is a sectional view taken along line II-II of FIG. 2,  
         [0023]    [0023]FIG. 4 is a detail shown in a view similar to FIG. 2 of an engaged locking pin bent after a crash to explain the clutch effect,  
         [0024]    [0024]FIG. 5 is a side view according to FIG. 2 of another exemplary embodiment of a locking unit,  
         [0025]    [0025]FIG. 6 is an embodiment similar to FIG. 5, but now with the locking pins provided with several individual grooves forming together the crash groove,  
         [0026]    [0026]FIG. 7 is a bottom view of a guide member with a non round pin bore and with non round contours in the region of the projections, the guide member being part of an L-shaped angular section and  
         [0027]    [0027]FIG. 8 is a view of a locking pin in the clutched engagement like in FIG. 4, but now with several individual grooves. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    The firs exemplary embodiment according to the FIGS. 1 through 4 is described herein after. Then, the other exemplary embodiments will be described as far as they differ from the first embodiment.  
         [0029]    The FIGS. 1 through 3 each depict one couple of rails consisting of a seat rail  20  and a corresponding bottom rail  22 . The rails are relatively slidable by way of suited sliding or rolling means configured as balls  24  (see FIG. 3). As may be more specifically surveyed from FIG. 3, the seat rail  20  consists of two assembled individual sections. The two rails  20 ,  22  from the boundary of an elongate hollow space  26 . The lower leg of bottom rail  22  is configured as a catch bar  28  extending in the longitudinal direction of the rail. Said catch bar  28  has periodically arranged snap openings  30 , also termed windows, and snap studs  32 . As more specifically shown in the FIGS. 2 and 3, the catch bar  28  is located in an upward bent bead  29 . At the summit of the bead  29 , the material of the lower flange of the bottom rail is bent upward by about 1.5 to 2 mm. The width of bead  29  approximately corresponds to the width of catch bar  28 . The offset formed be bead  29  may be surveyed more specifically from FIG. 2. The catch bar  28  is reinforced by the bead  29 .  
         [0030]    An L-shaped angular section  34  is located in the hollow space  26 , the vertical leg or second flange of the L of said angular section being fastened to the inner face of a vertical flange of seat rail  20 . A first flange or fee leg of said angular section  34  forms a guide member  36 . For pin bores  38  are provided therein. Each pin bore  38  receives a locking pin  40  which, in the exemplary embodiment shown, is rotationally symmetrical. The locking pins  40  are all build according to the same principle. Non round pins, e.g., such with a square cross section, are possible.  
         [0031]    The locking pins are individually biased by a spring  42  into a locking position and may be jointly pulled into the release position by way of a release member  44 . This needs not be discussed in detail, the reader is referred to the already mentioned EP 498 932 B.  
         [0032]    As shown in the FIGS., the locking pins  40  are slightly longer thant the height of the hollow space  46 . Whit their upper actuation region, they always remain outside of the seat rail  20  and, in the locked condition, their free end engages into a snap opening  30 .  
         [0033]    IN the first embodiment, the lower, free end of the locking pins  40  is formed by a truncated region  46 . At the upper end thereof, it turns into a cylindrical region  48 . This region however is interrupted, just above where it begins, by a groove, also termed a crash groove. The cylindrical region  48  is tapered in the region of the groove  50 . At its lower end, the groove  50  has a sharp-edged transition to the intact cylindrical region  48 , this condition being still more obvious in the other exemplary embodiments.  
         [0034]    The locking pins  40  are moreover guided in holes in an upper leg of seat rail  20 . Said holes are located from the guide member  36  at a distance that is considerably greater than half the length of the locking pins. Generally speaking, this results in the locking pins  40  being efficiently supported over a great distance, a large lever arm being thus created.  
         [0035]    Beneath each pin bore there is a projection  54  that extends downward as a continuation of the fin bore. It is preferably configured to form a rimmed hole, which will be discussed later, any configuration is possible in principle, though. It is connected to, and integral with, the remaining portion of the guide member  36  and is formed in the material thereof. In the axial direction, its length corresponds to about 60% of the material thickness of the guide member  36 . In the radial direction, the annular projections  54  are relatively thin, their material thickness ranges from 1 to 3 mm.  
         [0036]    If the projections  54  are configured as rimmed holes in the embodiment of preference, the process is as follows: at first, pilot holes are drilled at the location of the future pin bores  38 , said pilot holes having for example approximately 60% of the diameter of the future pin bore  38 . Then, a tool, more specifically a pin, is driven through the pilot hole to enlarge said pilot hole until it meets the size of the pin bore  38 , said pin forming, as it exits, the projection  54  together with that portion of pin bore  38  extended as a continuation by said projection.  
         [0037]    To provide the clutched engagement in accordance with the invention, that portion of the projection is substantially needed that, viewed from the center of a pin bore  38 , is located in the longitudinal direction of the rails  20 ,  22 . In the transverse direction, the projection may be flatter.  
         [0038]    As more specifically depicted in the FIGS.  2  to  4 , the groove  50  for those locking pins which are engaged is located slightly beneath the lower end of the corresponding projection  54  in the region thereof. As a result thereof, when, in the event of an accident, the locking pin  40  is pushed upward and additionally warped (see FIG. 4), a lower edge of the groove  50  abuts on the neighboring edge of projection  54  in the warp direction. This allows for the desired interlock in an accident condition. The lower boundary of groove  50  is preferably edged or is oriented approximately at right angles with the axis of the pin. The greatest possible stop face is thus achieved, which prevents the locking pin  40  from bouncing upward.  
         [0039]    The projections  54  are located on the lower face of guide member  36  and in proximity to the snap stud  32 . The spacing between guide member  36  and snap stud  32  is slightly smaller than the axial length of the truncated region  46 .  
         [0040]    The guide member  36  is made of a steel with a yield point value of 260 N/mm 2 . The locking pins  40  are also made of steel, but of a steel having a much higher yield point, of 600 N/mm 2  for example. The material thickness of the guide member  36  is approximately 3.5 mm. The projections protrude approximately 2 mm downward and have a wall thickness of about 1.5 mm. The projections  54  make the pin guidance softer and longer. In their cylindrical region  48 , the locking pins  40  have a diameter of about 7.5 mm. The pin bore  38  is a hole with an inner diameter of about 7.8 mm. The rails  20 ,  22  are made of a very hard steel, the yield point of which is even higher than that of the material of which the locking pins  40  are made. In the region of crash groove  50 , the diameter of the locking pins tapers to about 6.9 mm. The axial length of groove  50  is slightly smaller than the axial length of the complete pin bore  38 , i.e., in the guide member  36  and in the projection  54 .  
         [0041]    No groove is provided in the embodiment according to FIG. 5. In FIG. 5, the far right locking pin  40  is fully snapped in, it cannot be engaged any further. The two central locking pins  40  are disengaged. The far left locking pin  40  is engaged, but not completely lowered so that possible play may still be compensated for. On account of the point contact between the locking pin and projection  54 , the achievable interlock is still sufficient even in this condition in the event of a bending occasioned by an accident, see FIG. 8.  
         [0042]    [0042]FIG. 6 depicts a configuration similar to that of FIG. 5, a groove  50  is again provided, said groove being formed by a plurality of individual grooves  56 . Between the individual grooves, the locking pin  40  has again the diameter of the cylindrical region  48 . As a result thereof, the guidance of the locking pin  40  within pin bore  38  is enhaced. The several individual grooves  56 , with their increased number of lower grove edges, provide more options for the projection  54  to engage with. The pin guidance is also enhanced. Three respective individual grooves  56  are provided in FIG. 6. They extend over an axial length which is considerably greater than the axial length of the single groove  50  in the previous embodiments. In factual terms, they extend over approximately 70% of the maximum distance the locking pins  40  are capable of travelling. The length of the maximum travel also substantially corresponds to the axial length of the truncated region  46 .  
         [0043]    The individual grooves have an axial measurement of e.g., 2 to 4 mm. An intact region with a full cross section of approximately 0.1 to 3 mm in axial dimension remains between two individual grooves.  
         [0044]    In the embodiment of FIG. 6, the pin bores  38  are moreover non round, as more specifically shown in FIG. 7. By contrast, the pins are round. In fact, the cross sections of the pin bores  38  in FIG. 7 are approximately cushion-shaped, approximating the shape of a square with rounded corners. As a result thereof, there is still enough guide area on the one side. On the other side, plastic deformation is allowed to take place in the region around the pin bore  38 . Said plastic deformation occurs under a defined load, as it is encountered in an accident situation. The groove edges are allowed to better engage.  
         [0045]    Finally, FIG. 8 shows, in a way similar to that in FIG. 4, how the locking pin  40  in the bent condition is utilized in the embodiment in accordance with FIG. 5. It may be surveyed that interlocked engagement between the locking pin and the projection  54  has been achieved.  
         [0046]    The lower, free border of the projections  54  is preferably sharp-edged. The projections  54  are preferably hardened, e.g., case hardened. The projections  54  are more specifically formed at those locations toward which the locking pin may be bent, that is to say in the direction of longitudinal adjustment. In the transverse direction, that is to say across the longitudinal direction of the rails, the projections  54  may be dispensed with, be configured to be low, and so on.