Abstract:
In a rigid axle for a vehicle, comprising an axle body, on whose ends wheel carriers are arranged, and at least two trailing arms that are fixed to the axle body, the respective free end of a first section of the corresponding trailing arm being mounted in an articulated manner on a vehicle bearing block, while the free end of a second section that extends beyond the axle body is configured as a spring bracket and is supported on the vehicle body bearing block via at least one spring element, the axle body has, for each wheel side, a flange face with bores, to which a spring bracket can be adjustably mounted by means of separate mounting elements that extend through the bores so as to facilitate adaptation to various vehicles.

Description:
[0001]     This is a Continuation-In-Part Application of International Application PCT/EP03/005683 filed May 30, 2003 and claiming the priority of German application 102 31 376.8 filed Jul. 11, 2002. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to a rigid axle for a vehicle, comprising an axle housing, on whose ends axle journals or wheel carriers are arranged, and at least two trailing arms which are fixed to the axle housing in a rigid manner, the respective free end of a first section of the corresponding trailing arm being mounted in an articulated manner on the vehicle body, while the vehicle body is supported on the free end of a second section that extends beyond the axle and is configured as a spring bracket, by at least one spring element.  
         [0003]     DE 198 18 698 A1 discloses such a rigid axle for a vehicle, which comprises an axle tube and trailing arms arranged thereon. The individual trailing arm is extended rearward beyond the axle tube, forming a spring bracket. Its free end there is used as a support for an air spring. The spring bracket and the axle tube are configured in the common mounting joint in such a way that the spring bracket can be displaced vertically relative to the axle tube. Once an individual position of the spring bracket, for example matched to a specific vehicle, has been set, the bracket is welded to the axle body. In this way, the vehicle can be designed, for example, for a particular ground clearance desired by a customer.  
         [0004]     U.S. Pat. No. 5,954,351 discloses a suspension for air-sprung vehicle axles. In this case, guide arms are connected to an axle body that carries vehicle wheels, are attached to a vehicle body at their leading end in the direction of travel and, at their rear end, form a support for an air spring. For this purpose, the rear end of the guide arm has a large number of holes, via which the air spring is attached to the guide arms.  
         [0005]     It is the object of the present invention to provide a rigid axle for a vehicle including components which facilitate adaptation to various automotive and/or towed vehicles. The variants predefined by the components are intended to be produced only during the final mounting.  
       SUMMARY OF THE INVENTION  
       [0006]     In a rigid axle for a vehicle, comprising an axle body, on whose ends wheel carriers are arranged, and at least two trailing arms that are fixed to the axle body, the respective free end of a first section of the corresponding trailing arm being mounted in an articulated manner on a vehicle bearing block, while the free end of a second section that extends beyond the axle body is configured as a spring bracket and is supported on the vehicle body bearing block via at least one spring element, the axle body has, for each wheel side, a flange face with bores, to which a spring bracket can be adjustably mounted by means of separate mounting elements that extend through the bores so as to facilitate adaptation to various vehicles.  
         [0007]     Rigid axles of this type for vehicles are used, inter alia, as trailer axles for heavy commercial vehicles. Within such an axle, the trailing arms, as viewed in the direction of travel, are divided behind the axle tube or axle body. The front part comprises, for example, a shaped part which is complex and whose shape is optimized and which can be used to the same extent for all variants. Together with the axle tube, it forms a functional unit which supports the multi-axle static and dynamic vehicle loads, lateral and transverse forces in a dimensionally rigid manner on the vehicle body. In addition, the front part also has a stabilizer function.  
         [0008]     Individual parts generally used in pairs, such as the axle body section, trailing arm section and wheel head section are assembled in accordance with the track width and permissible axle load and, for example, in each case welded to one another at the end by friction welding. During assembly, for example in order to configure an axle for a trailer whose track width is greater than the standard track width, a longer axle body can be used. Instead of the longer axle body, if the frame width is unchanged, longer axle journals or wider trailing arm sections can also be used.  
         [0009]     By means of welding sections at their ends, doubling of material in the welding zone is avoided. In this way, the axle weight is reduced without any loss of strength. In addition, the formation of corrosion is reduced as a result of avoiding overlapping joints and gaps, and weld testing is made easier. The reduction in weight reduces the unsprung axle mass and thus, inter alia, moderates the tendency of the rigid axle to tramp. The latter improves ground adhesion and thus driving safety. This also has a positive effect on the service life of the tires.  
         [0010]     The rear part of the axle, which is represented by the respective second section of the trailing arms, is likewise specific to the vehicle. It is designed as a relatively simple spring bracket. As compared with the front part of the axle, this spring bracket has to absorb only relatively low, normally single-axle, loads. Consequently, it can be produced, for example, from more economical materials and/or with simpler fabrication methods. The brackets can be injection moldings, shaped sheet-metal parts, simple welded constructions or forged parts. Since they are fixed only during final mounting, that is to say only to the finally painted axle body, by means of simple mounting means such as rivets or bolts, coordination of materials necessary to a certain extent during welding is not necessary. For example, in each case a spring bracket of fiber reinforced plastic for each wheel side can be mounted on a steel axle body.  
         [0011]     In order also to ensure adaptation to different rim depths and/or tire widths, more fixing holes than necessary are made on the axle body for each wheel side, so that the distance between the brackets and the center of the vehicle can be varied in one or more steps.  
         [0012]     Furthermore, different brackets are available with respect to the geometric shape for different vehicle types.  
         [0013]     The invention will become more readily apparent from the following description of preferred embodiments thereof on the basis of the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  shows the outer part of a rigid axle for a vehicle in a perspective illustration;  
         [0015]      FIG. 2  shows a mounting bracket with a double reinforcement web;  
         [0016]      FIG. 3  shows a mounting bracket with a single reinforcement web;  
         [0017]      FIG. 4  shows a mounting bracket with a peripheral flange; and  
         [0018]      FIG. 5  shows a hole pattern for each wheel side of the rigid axle. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]      FIG. 1  shows by way of example a right outer region of a towed commercial vehicle trailer or semi trailer, without wheel or brake.  
         [0020]     According to  FIG. 1 , the axle part illustrated comprises an axle body section  1 , a right-hand trailing arm section  10  and a wheel head section  60 . At its leading end, for example pointing in the direction of travel, the trailing arm section  10  is fixed such that it can be pivoted in a manner of a cardan joint in an articulated bearing arrangement  70  by means of an elastomer body in a bearing block  80  mounted on the vehicle body. It is supported with respect to the bearing block  80  by means of a shock absorber  85 . The trailing end of the trailing arm section  10  is supported on the vehicle body, not illustrated, for example via a spring element  87  in the form of an air spring.  
         [0021]     The axle body section  1  comprises, for example, a cylindrical, smooth axle tube. The axle tube( ), which can also be a polygonal profile, ends in the embodiment shown directly at the trailing arm section  10  with a straight, flat end face. The end face is aligned normally with respect to the center line  3  of the axle tube  1 .  
         [0022]     The trailing arm section  10  comprises, in functional terms, a central element  21  and an arm segment  14  having a joint eye, hidden here by the bearing block  80 . The central element  21  is drum-shaped and has two lateral, for example open, end faces. Toward the joint end, the central element  21  is followed by the arm segment  14 . The two parts  21 ,  14  comprise, for example, a lower shell ( 15 ) and an upper shell  16  shaped from steel sheet. The two shells  15 ,  16 , for example, are designed mirror-symmetrically with respect to each other and are welded to each other. The welded joint lies, for example, in a plane which is covered by the axle tube center line  3  and the center line  71  of the joint bearing  70 .  
         [0023]     The arm segment  14  has, for example, a cross section that varies over its entire length. In the region of the central element  21  it has at least approximately an elliptical cross section, the large major axis of the ellipse being located parallel to the axle tube center line  3 . The large semi axis is approximately 2.3 times larger than the small semi axis. In the region of the joint end, the cross section is oval, the vertical extent being about two to three times larger than the horizontal transverse extent. Between these two outer regions, at approximately half the length of the shell, there is a central region which has a virtually round cross section.  
         [0024]     The aforementioned cross section in the region of the central element  21  is, for example, 5.5 times larger than the cross section in the region of the joint eye. The virtually round cross section located in the central region is, for example, 4.6 times smaller than the cross section in the region of the central element  21 .  
         [0025]     On the side facing away from the arm segment  14 , the central element  21  has a supporting lug  23 , as it is known. In the plane of the drawing according to  FIG. 2 , the latter has a trapezoidal contour with, for example, one flange face  24 . The flange face  24 , for example at least in its central region, is aligned normally with respect to a connecting line which represents the shortest connection between the center lines ( 3 ) and ( 71 ). The spring bracket  30 ,  31 ,  41 ,  51  is adapted, in cross section, to the supporting lug  23  which can also be triangular, for example, and to the flange face  24 .  
         [0026]     The spring bracket  30  according to  FIG. 1  is a bracket, illustrated schematically, for connecting the rigid axle to the spring element  87 . It is fixed permanently, for example via five rivets  28 ,  29 , for example blind or explosive rivets, of which only four are illustrated, in two rows on the central element ( 21 ). The four rivets  28  of the upper row  26 , cf.  FIG. 5 , bear the main load of the connection between the rigid axle and the bracket  30  in normal vehicle operation. The rivet  29  of the lower row  27 , cf.  FIG. 5 , is in principle stressed only during spring extension.  
         [0027]     FIGS.  2  to  4  show different types of spring and mounting brackets  31 ,  41 ,  51 . All three brackets  31 ,  41 ,  51  have, for example, a curved adapter face  32 ,  42 ,  52 . The curvature corresponds to a section of a shell of a cylinder, when the bracket  31 ,  41 ,  51  is mounted, the center line of the corresponding cylinder running parallel to the center line ( 3 ) and, for example, being located in the region between the center lines  3  and  71 .  
         [0028]     The spring bracket  31  according to  FIG. 2  is shaped as a curve profiled support. The mounting bracket  31  comprises an upper large part subjected to tension, a flat flange  33  which is shaped like a sickle and which extends over the entire component width. Underneath the flange  33  there are two part flanges  34 ,  35 , which extend as far as the rear adapter face  32 . Between the upper flange  33  and the lower part flanges  34 ,  35  there are arranged at least two approximately vertically aligned, for example parallel, webs  36  which connect the flanges, at least in some regions. The web height in the middle of the mounting bracket  31  is approximately twice as high as at the free bracket end facing away from the adapter face  32 . At the said bracket end, the webs  36  project beyond the part flanges  34 ,  35  by a length which corresponds approximately to the web height.  
         [0029]     In the region of the adapter face  32 , there is also a rear flange between the webs  36 , so that the adapter face ( 32 ) forms an uninterrupted curved face, with the exception of the fixing recesses and holes. In the upper zone of the adapter face  32  there are four holes  38 . Underneath these holes  38 , arranged centrally in relation to the adapter web, is a fifth hole, not visible here, cf. rivet  29  from  FIG. 1 . This hole lies between the webs  36 . The corresponding rivet  29  can be inserted into the central hole with the riveting tool via the clearance  37  located between webs  36  and can be riveted there.  
         [0030]     Machined into the free end of the upper flange  33  is a hole  39 . The latter is used for fixing the spring element  87  used. In  FIG. 2 , the adapter face  32  and the spring element support face located around the hole  39  form an angle of less than 90°. The angle is specified on the adapter face  32  in relation to a tangential plane which makes contact approximately at the central level of the adapter face  32 . A plane lying in the spring element support face intersects the adapter face  32  approximately at half the height.  
         [0031]     The mounting brackets  31 ,  41 ,  51  rest with their entire area on the supporting lug  23 , at least in the area covered by the holes  28 ,  29 , irrespective of their curvature or arching. The matched curves of the flange face  24  and adapter faces  32 ,  42 ,  52  can also be spherical. The center or centers of curvature then also lie, for example, in the region in which the center line of the previously described cylindrical curvature is located.  
         [0032]     The spring bracket  41  according to  FIG. 3  has in each case a continuous upper flange  43  and a likewise virtually full-area lower flange  44 . The two flanges  43 ,  44  have approximately the same area and are connected to each other over their entire length by a vertical web  45 . The web height increases starting from the free end toward the adapter face  42 . Over about two thirds of the bracket length, between the web  45  and the lower flange  44 , there is a tubular web  46 . The tubular web  46  connects a lower bore area—for the rivet  29  from  FIG. 1 —to a large, approximately elliptical or oval opening area in the lower flange  44 . Its outer contour tapers in the manner of a truncated cone, for example over the last fifth of its total length. On the inside, the tubular web  46  has the contour of a two-stage bore. The larger front region is for example shaped in the manner of a truncated cone. The region of the hole having the smaller diameter accommodates the lower rivet or screw.  
         [0033]     In the mounting bracket  41 , the physical arrangement of the spring element supporting face surrounding the hole  49  corresponds approximately to that of the bracket  31 . However, the bracket  41  is narrower than the bracket  31 . In addition, it has only three bores  48  in the upper region.  
         [0034]     The spring bracket  51  according to  FIG. 4  is shaped largely as a curved I beam. The I beam comprises an upper, flat flange  53  largely subjected to tension and curved in the shape of a sickle, a comparable lower flange  54  loaded more in compression, and a central web  55  which connects the two flanges  53 ,  54 , at least in some sections. At the free end of the bracket  51 , the flanges  53 ,  54  merge seamlessly and tangentially into each other in a half-round curve. Around the region of the bore  59 , the two flanges  53 ,  54  have a constant spacing. Toward the adapter face  52 , the web  55  broadens by about twice or three times the web height in the vicinity of the bore. Toward the supporting lug  23 , the lower flange  54 , as opposed to the bracket  30 ,  31 ,  41 , merge is smoothly curved to continuously into the full-area adapter face  52 .  
         [0035]     For the purpose of fixing the bracket  51  by means of a lower rivet  29 , the upper flange  53  is provided for example in its upper third with a cylindrical recess  56  which is cylindrical or shaped in the manner of a truncated cone or the like and has a flat base. In the center of the recess  56  there is a bores  57 . By providing the recess  56 , the upper and lower rivets  28 ,  29  or comparable screws can have the same overall size.  
         [0036]     The face of the lower flange  54  that acts as an adapter face  52  forms an angle of more than 90° with the spring element supporting face around the bore  59 . The angle is 120°, for example. In addition, the plane in which the spring element supporting face extends intersects the lower flange  54  underneath the contour acting as adapter face  52 .  
         [0037]     The respective spring bracket  31 ,  41 ,  51  is fixed to the central element  21  via, for example, four or five rivets  28 ,  29 . According to  FIG. 5 , for this purpose there are in the central element  21 , for example six holes in an upper  26  row and four holes in a lower row  27  of holes. This bore pattern is designed for a bracket  41 ,  51  having four bores  48 ;  57 ,  58 . In each case three bores in the upper row  2  with a fourth bore from the lower row  27  belong to a bore pattern group  6 - 9 . In each case one bore pattern group is available for positioning the corresponding bracket  41 ,  51  on the central element  21 . Therefore, depending on the axle design, the brackets  41 ,  51  for each wheel side are able to assume four different positions, each position having a different spacing with respect to the axle center. The bores that are not needed are closed, for example by means of plastic or rubber plugs.  
         [0038]     According to  FIG. 1 , an axle journal  61  is arranged beside the trailing arm section  10  in the extension of the axle tube center line  3 . The axle journal is substantially a rotationally symmetrical part for mounting the wheel, which has one end face oriented normal with respect to the center line  3  toward the trailing arm section ( 10 ). In the vicinity of this end face, a brake carrier flange  63  is integrally molded on the axle journal  61 .  
         [0039]     The axle tube  1 , the trailing arm sections  10  and the axle journals  61  are all arranged in axial alignment with one another. The axle tube  1  is butt-welded to the inner arm face of the trailing arm section  10 , and the axle journal  61  is butt welded to the outer end face. The welding method used is, for example, friction welding.  
         [0040]     Depending on the axle, the axle tube  1  arranged between the trailing arm sections  10  can also be omitted. In this case, the inner end faces of the central elements  21  are welded directly to each other. If necessary, the central element is lengthened toward the center of the axle for this purpose.  
         [0041]     The trailing arm section  10  is mounted in the bearing block  80  by means of an elastomer body, not illustrated. The latter is seated in the joint eye, for example pressed in. The elastomer body is fixed in the bearing block  80  with the aid of a bolt  82 . The bolt ( 82 ) is supported on the bearing block ( 80 ) at both ends in eccentric washers  83  between lateral stops for adjusting the track.  
         [0042]     On the bearing block  80 , toward the axle, there is a box-like projection  81 . Between this projection ( 81 ) and the screw  86  arranged in the bottom region of the arm segment  14 , a shock absorber  85  is installed.