Abstract:
An assembly comprised of a brake disk with a hub. Webs which are adjacent to one another in the circumferential direction extend between and are anchored to the brake disk and are attached to the hub. At least two of the webs which are adjacent to one another in the circumferential direction are formed together in one piece, either from a bent section joining the webs or because adjacent segments having respective adjacent webs are attached. The webs absorb stresses between the brake disk and the hub.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an assembly comprised of at least one brake disk with a hub comprised of webs which are adjacent to one another in the circumferential direction between the brake disk and the hub, wherein the webs which are anchored to the brake disk are attached to the hub. 
   BACKGROUND OF THE INVENTION 
   An assembly of this type is described in AT 265359. A brake disk having a cast friction body is connected by spokes to a hub made of steel. The hubs are individual iron profiles. In order to manufacture the assembly, the spokes are first embedded in a casting mold for the friction body and are cast in order then to be welded to the outer surface of the hub. 
   Such an assembly can be used for easily connecting brake disks and brake disk pots which are made of different materials to one another. One of the objectives in the manufacture of modern disk brakes for motor vehicles is rapid, simple and cost-effective mounting of such an assembly. Having a large number of individual spokes which have to be inserted into the casting mold and subsequently adjusted has a disadvantageous effect on the fabrication times and on the precision of the assembly. 
   Technical requirements for such an assembly are stringent. Different thermal expansion rates between the friction ring and the brake disk pot have to be compensated for without thermal stresses or deformations (known in the specific field as corrugations) of the brake disk occurring. Accordingly, the assembly must be elastic enough for expansions of the brake disk due to heating in both the radial and axial directions to be sufficiently compensated between the brake disk chamber and the brake disk. 
   SUMMARY OF THE INVENTION 
   The object of the invention is therefore to provide an assembly comprised of a brake disk and a hub which is easy and cost-effective to manufacture and which also fulfills the stringent requirements in terms of compensating for thermal expansion rates. 
   This object is achieved by the invention which concerns an assembly comprised of at least one brake disk with a hub. Webs which are adjacent to one another in the circumferential direction extend between and are anchored to the brake disk and the hub. At least two of the webs which are adjacent to one another in the circumferential direction are formed together in one piece, either from a bent section joining them or because adjacent segments having respective adjacent webs are attached. The webs absorb stresses between the brake disk and the hub. 
   The term hub is to be understood as referring to all hub-like mechanical connecting elements which connect to a wheel or to a plurality of wheels of a vehicle and which are also suitable for transmitting braking torques to the wheel or wheels in the circumferential direction. The classic example of such a hub is a brake disk chamber which is connected to the wheel body by bolts. 
   At least two of the webs of the assembly which are directly adjacent to one another, or preferably all of the webs or spokes of the assembly, are bent together to form one piece from a bent profile to form a ring in the shape of a star. Alternatively, individual segments made of bent profile are either attached to one another in the circumferential direction of the hub to form a ring which is formed in the shape of a star, or alternatively the segments are inserted individually into the brake disk or between the brake disks and are then connected to the hub. 
   The profile may have any desired cross sections, for example that of a square which is rectangular or quadratic in section, or cross sections of round profiles. The cross sections have identical or alternatively changing geometric dimensions along the profile. 
   The profile, which is preferably a round steel with a diameter in the cross section of 5-10 mm, is bent. The profile which is in one part and thus has all the limbs is connected to the bending ends which are brought together. The tips of the prongs of the ring which point radially outward are rounded, for example, by bending radii of the wire. It is also conceivable to use a ring which is bent in a meandering shape and has radially outwardly pointing clips. 
   The individual segments are bent into their defined, clip-shaped form, as an alternative to a ring made of a profile. The radially outwardly pointing ends of the limbs are either flattened in the region of the limbs which is anchored to or in the brake disk, or are alternatively upset in the shape of nail heads or optionally also bent over in tangential directions. 
   The prongs of the star-shaped profile or the outwardly projecting free ends of the limbs are preferably connected to the cast material of the brake disk by casting. It is conceivable here for the surface of the region which is surrounded by casting to be provided with a separating agent before the casting is carried out around it. Such webs which are embedded in the brake disk are not rigidly connected to the brake disk but rather can move separately, in particular radially, in the brake disk of the cast material within a small degree of play by virtue of the separating layer. Thermal expansions of the brake disk are thus compensated by means of relative movements of the brake disk with respect to the webs. 
   The profile is preferably rigidly connected to the material of the brake disk since elastic compensation of the thermal expansion of the brake disk is accomplished by the regions of the webs which extend radially in the direction of the hub and which in doing so, project into the annular gap between the hub and brake disk. 
   The limbs or the segments are either arranged along the circumference of the hub to have the same pitch as one another or are optionally adjacent to one another along the circumference with different intervals. 
   The hub which is preferably embodied as a brake disk chamber has attachment holes around the central hole in the centrally perforated base of the chamber. In order to attach the brake disk chamber to the vehicle, in each case one screw or clamping bolt or other attachment or bolt engages axially through each of these attachment holes. The brake disk chambers generally have three, four or five of these attachment holes. The attachment holes are spaced apart from one another at the same radial distance from the axis of rotation of the hub and generally with uniform pitch, that is with the same distance measured in radians along the circumference. One embodiment of the invention provides for the number of webs of the assembly to be at least precisely as large as the number of the attachment holes in the flange of the hub on which the assembly is formed. This also provides for the number of webs to be an integral multiple of the number of attachment holes. 
   A further embodiment of the invention provides in each case for two of the webs in the circumferential direction of the hub with a section of the profile of the webs to be connected to one another. From this arrangement, the webs are generally formed in one piece with the section. The section bears radially against the outside of the hub and is connected there to the hub, as are also the webs. 
   It is conceivable that at least every pair, or every second pair, of two of the webs which are directly adjacent to one another is arranged along the circumference on each side of an imaginary axial plane which starts from the axis of rotation, being aligned longitudinally with the axis of rotation, and in which in each case the central axis—extending in the same direction as the axis of rotation—of one of the attachment holes lies. The axial plane forms an interface with the surface of the hub. Preferably at least every second section bears against the interface on the surface of the hub and is attached to this interface or at least along the circumference on each side of this interface of the hub, preferably by welded connections. 
   The previously described relationship between the axial and circumferential orientation of the attachment points of the webs on the hub to the attachment holes is important here in particular if the hub/brake disk system is to be adjusted in an optimum way so that the anticipated deformations of the brake disk are as small as possible. By means of the previously mentioned measures, the deformations and stresses in the system, which would otherwise have an unfavorable influence on one another can be selectively isolated from one another, or are partially or entirely prevented by means of these measures. Such deformations are produced, for example, by screwing of the hub into the attachment holes, by thermal stresses on the assembly and on the brake disk and also as a result of the application of brake torques to the system. 
   Pairings of different materials in the assembly are provided. The objective is that at least the materials of the brake disk and of the profile will have identical coefficients of thermal expansion. The materials of the brake disk are, for example, grey cast iron, ductile cast iron and ceramics. 
   The material of the profile/profiles is preferably a non-rusting steel. It is conceivable, for example, to use ferritic and at the same time rust-resistant steel. It is also possible to use any desired weldable types of steel. The webs or alternatively the entire assembly are coated on the surfaces either before they are attached to one another or afterward to provide protection against corrosion, for example. An alternative to attaching the profile by welding is riveting, for example. 
   The brake disks are provided on the axially lateral friction faces with axial depressions which preferably extend radially over a specific width of a few millimeters and of an axial depth into the brake disk and which are directly axially adjacent to the region at which the limbs are anchored to the brake disk. As a result, deformations such as axial corrugations on the brake disk due to different thermal expansion rates of the materials which are anchored to one another are avoided. 
   The assembly is generally more elastic at the profile in the radial annular gap between the brake disk and the hub than the comparatively rigid structures of the hub and of the brake disk. Such an assembly makes it possible to prevent deformations on the brake disk such as “corrugations” and to compensate for thermal expansion of the brake disk in the radial and axial directions. In the radial gap, the profile is therefore at least radially elastic enough to compensate such deformations in an elastically flexible fashion, and rigid enough in the tangential or circumferential direction of the hub to transmit the braking torques via the assembly virtually without deformations. 
   The assembly is easy and cost-effective to manufacture. The elasticity of the webs in the annular gap can be adjusted easily and virtually to any desired extent by changing the geometry of the assembly. 
   Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail below with reference to exemplary embodiments. In the drawings: 
       FIG. 1  shows an exemplary embodiment of a wire ring for the assembly according to the invention, 
       FIG. 2  shows an overall view of a unit comprised of a brake disk and brake disk pot which are connected to one another by means of an exemplary embodiment of the assembly according to the invention, shown in a partially sectional view, 
       FIGS. 3 and 4  show further exemplary embodiments of a wire ring for the assembly according to the invention, the wire ring being comprised of individual segments each having two limbs, and 
       FIG. 5  shows a front view of the unit comprised of the brake disk and brake disk pot showing an example of the circumferential orientation of the webs with respect to the attachment holes. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   A connector element  1  shown in  FIG. 1  is a continuous, generally ring shape  2  made of wire, and the ring is formed in the shape of a star. The ring  2  has a profile with a round cross section and is star shaped to define prong-like pins  3  which are directed radially outward. Each of the pins  3  is formed by two webs  4  of the ring which are directly adjacent to one another. The webs  4  merge into one another in the circumferential direction regions between the pins of the sections  2   a  and  2   b  of the ring. 
   The shape of each section  2   a  is predefined by the bending radius r 1  of the neutral bending line N. The sections  2   b  are firstly described by the radius R 1  with respect to the bending line N. The radius R 1  is the internal radius of the ring  2 . The radius R 1  corresponds to the external radius of the seat of the ring  2  on a hub  5  according to  FIG. 2  which is formed as a brake disk chamber, plus half the diameter d of the wire. Further along section  2   b  in both circumferential directions, it is curved radially outward and is described by the radii r 2 . At the radii r 2  sections  2   b  merge with the webs  4 , and the two webs  4  of each of the pins  3  merge with one another through one of sections  2   a  to form a U-shaped section. 
     FIG. 2  shows the connection of a brake disk  6  to the hub  5  by the ring  2 . The brake disk  6  is formed from two disk sections  7  which lie axially opposite one another. The disk sections  7  are connected to one another by means of radially aligned longitudinally extending ribs  8 . Venting slits  9  are formed between the longitudinal ribs  8 . 
   Anchoring elements  10  are formed on the brake disk  6  between its disk sections  7 . The number of anchoring means  10  and their pitch spacing along the circumference with respect to one another corresponds to the number of pins  3  and to their pitch spacing in the circumferential direction. 
   The hub  5  is formed as a brake disk chamber and has attachment holes  7  for attaching the assembly comprised of the brake disk  6 , ring  2  and hub  5  to the wheel. The ring  2  is seated on a circular-cylindrical section  12  of the hub  5 . The brake disk  6  is concentric with respect to the hub  5  and at the same time is arranged spaced apart from the hub  5  by a radial annular gap  13 . 
   The profile of the ring  2  first extends with the sections  2   b  in the radial and annular gap  13  between the brake disk  6  and the hub  5 . At the same time, the ring on the sections  2   b  is connected to the hub  5  by means of welds  14 . Further along, the profile overcomes, by means of the radially outwardly curved ends of the sections  2   b , the annular gap  13  in the direction of the brake disk  6  and finally passes between the disk sections  7  at the webs  4 . Anchoring elements  10  on at least one disk section engage around each of the webs  4 . 
   The embodiments of the invention provide a positively locking connection or alternatively a rigid connection between the ring  2  and the anchoring elements  10 . For a positively locking connection, at least the pins  3  are provided in the respective anchoring elements  10  with sliding layers/separating layers which permit relative movement (as a result of thermal expansion) of the brake disk  6  with respect to the pins  3  in the radial direction, which is indicated by the arrow  15 , after the material of the brake disk  6  has been cast around the ring  2 . 
   A positively locking engagement between the brake disk  6  and the ring  2  which is attached to the hub  5  is brought about in the circumferential direction indicated by the arrow  16  so that a braking torque can be transmitted to the hub  5  by the brake disk  6 . 
   However, one preferred embodiment of the invention provides for the pins  3  to be rigidly connected to the brake disk  6  by the anchoring elements  10 . In this case, the webs  4  are firmly embedded in the anchoring elements  10 . Thermal expansion at the brake disk  6  is compensated for in this case into the free space of the annular gap  13  by elastic deformations of the webs  4 , in particular at the sections  2   b  and at the same time in turn in particular in the region of the radii r 2 . At the webs  4 , the ring  2  has a behavior which is comparatively elastic with respect to the rigid construction of the hub  5  and brake disk  6 . 
   Elastic compensation of thermal expansion and other deformations at the brake disk  6  in the annular gap  13  is generally provided both in the case of positive locking and also in the case of rigid anchoring of the ring  2  to the anchoring elements  10 . Alternatively, the hub  5  is also made elastically flexible in the radial direction if the hub  5  is provided, for example, with the slits  17  which are aligned axially (as indicated on the illustration). 
   The brake disk  6  is alternatively provided in the region of the anchoring elements  10  with the axial depressions  6   a  which are illustrated by dashed lines. Axial thermal expansion of the brake disk in the region of the anchoring element  10  is compensated for by the depressions  6   a.    
   The ratio of the radial immersion depth D of the pins  3  into the brake disk  6  with respect to the height H of the annular gap is in this case approximately 2:1. The elasticity of the connection between the brake disk  6  and the hub  5  is determined by this ratio, by the radial height H of the annular gap and thus by the lever ratios prevailing at the webs  4 , as a function of the diameter d of the profile on the ring. The radial height H of the annular gap  13  with constant diameter d of the wire is directly proportional to the elasticity of the connection. By changing the height H and the diameter d and by means of different radii r 1 , r 2 , R it is possible to set the elasticity of the connection in an application-related fashion. 
     FIG. 5  shows, for example, that the assembly with 20 webs  4  has four times as many of the webs  4  as the quantity of attachment holes  11 , namely 5 holes  11 , which are formed in the flange  27 . In each case two adjacent webs  4  are formed in one piece by a section  2   a  and are connected to one another by the section  2   a  which this time is at the circumference of the hub. In  FIG. 5 , every second section of the sections  2   a  is located at least at a point of intersection S of the external contour of the hub  5  with one of the planes E and is attached to the hub at least there by means of the welds  26 . The plane E extends axially with the axis  28  of rotation into the plane of the illustration of  FIG. 5  and extends outward in the radial direction. The central axis  29  of each of the attachment holes  11  extends in the same direction as the axis  28  of rotation and lies in each case in one of the planes E. 
     FIG. 3  shows a further exemplary embodiment of a wire ring  18 . It is formed from individual wire segments  19  which are combined on the circumferential side of the hub  5 . Each individual segment of the segments  19  is of mostly arcuate shape and initially points radially outward with the free ends  21  of the webs  20 . However, the end sections of the free ends  21  of each segment  19  are bent to point to one another. At least the free ends  21  of the webs  20  are in the region of the ring  18  of the type anchored to the brake disk which is illustrated in  FIGS. 2 and 5 . 
     FIG. 4  shows a further embodiment of the invention in the form of a ring  22  comprised of segments  23  which are connected to one another at the circumference and at which segments have free ends  24  which are flattened in the region where webs  25  are anchored to the brake disk. In this arrangement, the limbs  25  are flattened out in the axial directions in comparison with the remaining round profile of the segments  23 . In each of  FIGS. 3 and 4 , the webs  20  and  25  which are directly adjacent to one another of two segments  19  and  23  which are adjacent to one another in the circumferential direction are attached to one another by means of welds  26 . 
   Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.