Abstract:
A steering column includes a locking device for securing a jacket tube in a predetermined and adjustment position and having a first locking member with an engagement member received in an at least one hole provided in the first locking member and displaceable between a first position in which it projects beyond the first locking member by a predetermined length, and a second position in which it is displaced into the at least one hole against a biasing force of a spring located in the hole, and a second locking member having a plurality of receiving holes associated with the at least one engaging member and spaced from the first locking member, in opened and closed positions of the locking device, respectively, by a distance which is grater or smaller than the predetermined length by which the engaging member projects in its first position beyond the first locking member.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a steering column including a jacket tube for receiving at least a section of a steering gear shaft, a bracket member for securing the steering column to a body of a motor vehicle, and a locking device having a closed position in which the jacket tube is fixedly secured to the bracket member, and an open position in which the jacket tube is displaceable, within predetermined limits, relative to the bracket member. 
   2. Description of the Prior Art 
   Different embodiments of a steering column, which is described above, are well known. Usually, in the open position of the locking device, both the length of the steering column and its inclination or height can be adjusted. For fixing the jacket tube in the closed position of the locking device, crossing each other, packs of lamellas are provided one of which is secured to the bracket tube and another of which is secured on the bracket member. The lamella packs are pierced by a locking bolt which is tensioned by a pull device. A steering column of the type described above is disclosed, e.g., in European Publication EP 0 802 104 B1. For effecting the necessary adjustment, crossing each other elongate openings are provided in the lamella packs, in the jacket tube, and in the bracket member, with the locking bolt extending through the elongate openings. Locking devices with lamellas or lamella-like elements are discloses, e.g., in European Publications EP 121 506 B1; EP-0 440 698 B1 and U.S. Pat. No. 5,606,891. The drawback of the steering columns, which including locking devices with lamellas, consists in that for obtaining a high retaining force in the closed position of the locking device, a relatively large number of lamellas is required. This results in that for adjusting the steering column in the open position of the locking device, a relatively large friction force has to be overcome. 
   European Publication EP-0 836 981 B1 discloses an adjustable steering column the locking device of which has toothed members the teeth of which engage each other in the closed position of the locking device. With this locking device, the adjustment of the steering column in the open position of the locking device can be effected rather easily. However, with the locking device of this type, there can be cases when the tips of opposite teeth are located directly opposite each other, and upon closing of the device, it cannot be properly closed. In case of a crash, an uncontrolled displacement of the steering column can take place. Furthermore, in case the tips of the teeth are located directly opposite each other, the device cannot be closed at all or is closed incompletely, and/or requires application of a substantial force for closing. 
   Accordingly, an object of the present invention is a steering column of the type discussed above and that can be easily adjusted in the open position of the locking device. 
   Another object of the present invention is a steering column of the type described above and the locking device of which can be easily closed in any of adjustment positions of the steering column. 
   SUMMARY OF THE INVENTION 
   These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a steering column the locking device of which includes a first locking member having at least one hole, an engagement member displaceably received in the at least one hole and displaceable between a first position in which it projects beyond the first locking member by a predetermined length, and a second position in which it is displaced into the at least one hole against a biasing force of a spring located in the hole, and a second locking member having a plurality of receiving holes associated with the at least one engaging member and wherein in the opened and closed positioned of the locking device a distance between the first and second locking members is, respectively, greater and smaller than the predetermined length by which the engaging member projects in its first position beyond the first locking member. 
   With the inventive locking device, in the closed position of the device, the at least one engaging member of the first locking member engages in an opposite receiving hole of the second locking member corresponding to a selected adjustment position of the locking device. If in the selected adjustment position, no receiving hole is located opposite the engaging member, the pull device can still be closed, as the engaging member is pushed further in its hole in the first locking member, with its free end abutting the surface of the second locking member between the receiving holes. When later, a force is applied to the steering gear shaft of the steering column, whether during a normal operation or in case of a crash, the force would lead to a small displacement of the two locking members relative to each other so that the engaging member would be able to engage in a respective receiving hole of the second locking member as soon as it finds itself opposite the respective receiving hole, whereby a further change of the position of the steering column is prevented. 
   According to an advantageous embodiment of the present invention, the first locking member includes a plurality of engaging members to each of which a plurality of receiving holes in the second locking members is assigned. Thereby, the length of the path between two adjustment positions of a steering column, in which a respective engagement member engages in a respective hole, can be made very short. 
   The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings show: 
       FIG. 1  a side view of a section of a steering column according to the present invention illustrating the inventive parts of the column; 
       FIG. 2  a side view of another side of the inventive steering column; 
       FIG. 3  a cross-sectional view along line  3 — 3  in  FIG. 1 ; 
       FIG. 4  a cross-sectional view of a portion of the view shown in  FIG. 3  at an increased scale; 
       FIG. 5  a bottom partially cross sectional view along line  5 — 5  in  FIG. 2 ; 
       FIG. 6  a view showing a section of the view shown in  FIG. 5  at an increased scale; 
       FIG. 7  a view showing a section of a steering column shown in  FIG. 6  in a closed position of the locking device; 
       FIG. 8  an exploded view showing first and second locking members; and 
       FIG. 9  a partial cross-sectional view showing first and second locking members in the locking position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A steering column according to the present invention, which is shown in  FIGS. 1-7 , has a bracket member  1  which is secured to a section of a vehicle body. The bracket member  1  has two legs  2  projecting downward and between which a jacket tube  3 , which has parallel side sections, lies. A section of a steering gear shaft  4  is received in the jacket tube  3  and is rotatably supported therein. A steering wheel is secured on a front end  5  of the steering gear shaft  4 . The opposite end of the steering gear shaft  4  is connected with other sections of the steering column (not shown in the drawings) in per se know manner. The sections of the steering column, which are not shown in the drawings, can be formed in a conventional manner and would not be described in detail. 
   The jacket tube  3  has two, downwardly projecting cheeks  6  which, e.g., are formed integrally with the jacket tube and, as shown in  FIG. 4 , are located between the legs  2  of the bracket member  1 . The cheeks  6  have elongate openings  7  which extend parallel to the steering gear shaft  4  and at an angle to elongate openings  8  formed in the legs  2 . The elongate openings  7  form, with the respective openings  8 , an of angle at least 45°. The elongate openings  7  serve for adjusting the steering column in the longitudinal direction of the steering gear shaft  4  which is formed as a telescopic part. The elongate openings  8  serve for an inclination or height adjustment of the steering column. In the embodiment shown in the drawings, the pivot axis of the inclination adjustment is formed by a bolt  9  secured on the bracket member  1  and extending through an elongate opening  10  which is formed in the jacket tube  3  and extends parallel to the elongate openings  7  formed in the cheeks  6  of the jacket tube  3 . However, the pivot axis of the inclination adjustment of the steering column could also be formed by a universal joint of the steering gear shaft itself. 
   A locking bolt  11  extends through the elongate openings  7 ,  8  which are formed in the jacket tube  8  and/or the bracket member  1 . The locking bolt  11  can be displaced to the right (in  FIG. 3 ) with a pull device  12 , with the steering column being locked with a locking device. The pull device  12  can include a cam element fixedly connected with a clamping lever  13 . The cam element has a plurality of circumferentially arranged cams  14  which cooperate with inclined surfaces  15  of a pressure member. Other pull devices, e.g., those according to the state of the art described in the introductory part of the specification, also can be used. 
   The locking device of the steering column includes first and second locking members  16 ,  17  which cooperate with each other in the locking condition of the locking device. As particularly shown in  FIGS. 8-9 , the first locking member  16  has a body  18  with a plurality of holes  19  an inner diameter of which is reduced at the side facing the second locking member  17 , whereby a stop shoulder is formed. Pin-shaped engaging members  20  are inserted into the holes  19  from the side of the holes remote from the second locking member  17 . The engaging members  20  have an outwardly projecting annular flange  21 . Springs  23  are arranged between the engaging members  20  and a cover plate  22  provided on a side of the body  18  remote from the second locking member and which is screwed to the body  18 . In an unloaded condition, the flanges  21  of the engaging members  20  abut the stop shoulders of the respective holes  19  under the action of the springs  23 , and the engaging members  20  themselves project beyond the side of the body  18  facing the second locking member  17  by a distance d (FIG.  4 ). The first locking member  16  also has a through-bore  24  through which the locking bolt  11  extends. Further, the body  18  has, on its side facing the second locking member  17  projections  25  provided with blind bores in which springs  26  are received. The springs  26  are formed as helical springs. Slide elements  27  are inserted into respective springs  26  from an end of the springs  26  remote from the body  18 . 
   The second locking member  17  is plate-shaped and has a plurality of rows of receiving holes  28  and an elongate opening  29 , with two rows of the receiving holes  28  being provided on each side of the elongate opening  29 . Each row of receiving holes  28  includes a plurality of spaced from each other holes  28  the centers of which lie on an imaginary straight line extending parallel to the longitudinal extent of the elongate opening  29 . 
   The engaging members  20  are associated with a respective row of receiving holes  28 . At that, a single receiving hole  28  can be associated with several engaging members  20  and vice versa. During the adjustment of the steering column, with the locking device being in an open position, several receiving holes  28 , which are associated with a respective engaging member  20  are brought alternatively in a position opposite the respective engaging member  20 . The closing of the locking device is effected in a position of the first locking member  16  in which a respective engaging member  20  is located opposite an associated receiving hole  28 , engaging therein in the locking position of the locking device (see  FIG. 9  where respective engaging members  20  engage in respective receiving hole  28 ). In case an engaging element  20  does not have an associated receiving hole  28 , it would be pressed into its hole  19  in the body  18  against the biasing force of a respective spring  23 . 
   When the locking device becomes closed in a position of the first locking member  16  in which no receiving hole  28  is located opposite any of the engaging members  20 , all of the engaging members  20  are pressed into the body  18 . In case a load is applied to the steering column (during a normal operation or in case of al crash) which would cause displacement of the first locking member  16  relative to the second locking member  17 , after a very short displacement, a position is reached in which a respective engaging member  20  engages in a respective receiving hole  28 . With the embodiment of the locking device shown in  FIGS. 8-9 , the arrangement of eight engaging members  20  and of four rows of receiving holes  28  are so selected that simultaneously always two engaging members  20  engage in respective receiving holes  28 . 
   For a steering column shown in  FIGS. 1-7 , the first and second locking members  16 ,  17  are used for both longitudinal adjustment and inclination adjustment. The first locking member  16  is secured, for setting the height position of the steering column, on the locking bolt  11  on an outer side of the leg  2  remote from the pull device  12 . The locking member  16  is secured with a nut  30  which is screwed on the locking bolt  11 . The second member  17  is secured to the outer side of the leg  2  so that the elongate opening  29 , which is formed in the locking member  17 , overlaps with the elongate opening  8  formed in the leg  2 . Basically, the second locking member  17  can be formed integrally with the leg  2  as part of the bracket member  1 . In this case, the elongate openings  29  and  8  coincide. 
     FIGS. 1 through 6  show an open position of the locking device. In this position of the locking device, the ends of the engaging members  20 , which project beyond the first locking member  16  are spaced from the second locking member  17 . The projections  25  extend through the elongate opening  29  in the second locking member  17  and/or through the elongate opening  8  in the leg  2 , whereby rotation of the first locking member  16  relative to the second locking member  17  is prevented. The springs  26 , together with the slide elements  27  likewise extend through the elongate opening  29  and/or the elongate opening  8  and are supported against the outer side of the jacket tube  3 , which provides for spacing of the first locking member  16  from the second locking member  17 . 
   Similarly, for setting the height of the steering column, a first locking member  16  of another locking device is secured on the locking bolt  11  in the region between the cheeks  6  of the jacket tube  3 . This first locking member  16  is supported against a shoulder of the locking bolt  11 , which prevents its displacement leftwardly (FIG.  3 ). The second locking member  17  of the another locking device is secured to the inner side of the cheek  6  of the jacket tube  3  which is located on the right in  FIGS. 3-4 . The elongate opening  29  of the second locking member  17  of the another locking device and through the elongate opening  7  in the cheek  6 , with the slide elements  27  being supported against the leg  2 . 
   When from an open position of the locking device shown in  FIGS. 1-6 , the clamping lever  13  is pivoted in the direction of arrow  31  (FIG.  1 ), the first locking member is pulled, in views shown in  FIGS. 3-4 , to the right toward the second locking member  17 . The locking position of the locking members  16  and  17 , for the case of the longitudinal adjustment, is shown in  FIG. 7  in which an engaging member  20  engages in a receiving opening  28 . 
   In the embodiment shown in the drawings, in the closed position of the locking device, the first and second locking members  16  and  17  are pressed against each other, whereby the two locking members become frictionally connected with each other in addition to a formlocking connection that results from engagement of the engaging member(s)  20  in the receiving hole(s)  28 . The frictional connection is amplified by the pressure applied by the engaging members  20 , which do not engage in the receiving holes ( 28 ) against the outer surface of the second locking member  17 . 
   Though frictional engagement of the first and second locking members  16  and  17  in the closed position of the locking device is preferred, it is also contemplated and possible that the first locking member  16  would not be pressed against the second locking member  17  in the closed position of the locking device. Rather, the first locking member  16 , in the later case, would be spaced from the second locking member  17  by a small distance smaller than the portion d by which the engaging member  20  projects beyond the first locking member  16 . In this case, in the closed position of the locking device, only a reduced frictional connection is obtained, which results from pressure applied by the engaging members  20 , which are not engaged in the holes  28 , to the surface of the second locking member  17 . The fixed connection of the first second member  16  with the second locking member  17  is insured by the formlocking connection formed as a result of engagement of the engaging member(s)  20  in the receiving hole(s)  28 . 
   In order to facilitate the engagement of the engaging members  20  in the receiving holes  28 , advantageously, the engaging members  20  are provided, in the region of the free end, with bevels  32  (FIG.  8 ). Generally, the engaging members  20  can have different profiles. However, advantageously, the engaging members  20  are formed as pin-shaped members. The receiving holes  28  can have a cross-sectional profile different from al circular profile shown in the drawings, e.g., they can have a rectangular profile. To compensate for the manufacturing tolerances, a corresponding play can be provided between the engaging members  16  and the receiving holes  28 . In order to facilitate the engagement of the engaging members  20  in the receiving holes  28  upon displacement of the first locking member  16  relative to the second locking member  17   m , e.g., in the case of a crash, a greater play can be provided between the diameters of the engaging member  20  and the receiving hole  28  in the displacement direction than in a direction perpendicular to the displacement direction. 
   It is to be pointed out that different modification of the present invention are contemplated and possible within the scope of the present invention. Thus, the bracket member and the steering column can have a construction different from that shown in the drawings. The possible constructions can be those disclosed in the stand of the art discussed in the introductory part of the specification, e.g., in addition to the bracket member and a jacket tube, a guide member can be provided relative to which the jacket tube can be displaced in the longitudinal direction of the steering gear shaft and which would support the locking bolt for displacement in the axial direction. The guide member can be arranged between the bracket member and the jacket tube. With such a construction, a locking bolt can be provided that would not completely extent through the jacket tube as in the embodiment shown in the drawings but would only project into the jacket tube. 
   Accordingly, though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the append claims.