Patent Publication Number: US-2023141095-A1

Title: Brake disc and a vehicle

Description:
TECHNICAL FIELD 
     The invention relates to a brake disc configured to be connected to a vehicle axle and to be squeezed between brake pads. The invention also relates to a vehicle comprising such a brake disc. 
     The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will be described with respect to a truck, the invention is not restricted to this particular vehicle, but may also be used in other vehicles such as cars. 
     BACKGROUND 
     Brake discs for vehicles are available in various forms. For instance, some brake discs have disc plates made of grey iron or other frictional material. Some discs plates are provided with a metallic or non-metallic (such as ceramic) coating. The disc plates may be attached to a wheel end hub in various ways. For instance, the disc plates may be riveted, adhesively bonded or thermally sprayed to the wheel end hub. When the disc plates have worn out, it is often necessary to replace the entire brake disc. 
     US 2017/184164 discloses a brake rotor assembly which has a structural part and friction surface parts which are joined together. The friction surface parts can for example be fixedly attached to the structural part by means welding or adhesive. Other alternatives which appear to provide the possibility of less permanent fixation are screws or bolts. Although it may be beneficial for the replacement of disc plates to provide separate friction surface parts that are screwed to, and unscrewed from, a structural part (as this would, only require replacement of the friction surface parts), this too has disadvantages. The screws and bolts will be subject to wear as brake pads are clamped to the disc plates during braking of the vehicle. Thus, not only may the strength of the screw and bolt become reduced, but wear of the heads of the screws or bolts, may result in quite a challenge when you want to unscrew the screws or bolts for replacing the disc plates. Furthermore, the presence of screws of bolts will also add to the (possibly uneven) wear of the brake pads. Thus, although US 2017/184164 is beneficial in some respects, there are still improvements to be made. 
     SUMMARY 
     An object of the invention is to at least partly mitigate the drawbacks of the prior art. This and other objects, which will become apparent in the following, are accomplished by the accompanying independent claims. 
     According to a first aspect of the invention, the object is achieved by a brake disc configured to be connected to a vehicle axle and to be squeezed between brake pads, comprising: 
     a central disc body having a first side and a second side, wherein the second side faces in the opposite direction compared to the first side, 
     a first disc plate and a second disc plate, each disc plate having a wear surface for producing friction when a brake pad is pressed against the wear surface, 
     wherein the first and the second disc plates are releasably secured to said first side and said second side, respectively, of said central disc body, so as to enable the first and second disc plates to be replaced by other disc plates, 
     wherein the brake disc has a geometrical centre axis, 
     wherein each one of the first and second disc plates has an inner periphery and an outer periphery extending from the wear surface to an oppositely located disc body facing surface, the inner periphery being located at a radially shorter distance to the geometrical centre axis than the outer periphery, wherein 
     said central disc body comprises
         a first ledge mating with the inner periphery of the first disc plate, and   a second ledge mating with the inner periphery of the second disc plate,       

     wherein each one of the first and second ledges comprises at least a ledge portion which is inclined relative to the geometrical centre axis for counteracting axial movement of the disc plates relative to the central disc body. 
     By the provision of ledges, at least a portion of which is inclined axial movement of the disc plates relative to the central disc body may be counteracted, without using screws or bolts extending through the wear surface of the disc plates. Thus, heads of screw or bolts which causes extra wear on the brake pads and which themselves become worn and deteriorated are avoided by instead providing inclined ledges or ledge portions in accordance with the present invention. Thus, the inventors of the present invention have realized that replaceable disc plates are possible to have without the drawbacks of the prior art by instead of holding the disc plates at their wear surface, you provide the central disc body with an abutment surface which at least partly extends at an angle to the axial direction, thereby presenting an axially limiting surface to the thereon resting disc plate. If desired, the outer periphery may also be supported by a similar inclined ledge, or by clamps or an enveloping sleeve, or any other means which do not affect the wear surface of the disc plates in the same negative manner as the prior art screws. 
     The ledge portion may have any suitable angle of inclination. It may The angle of inclination may for instance be 5°-80° relative to the geometrical centre axis, for instance 10°-50°, such as 15°-30°. However, the ledge portion could also form a radially projecting end face of the ledge, which could thus be perpendicular (i.e. extending 90° relative to the geometrical centre axis). For instance, the said ledge portion could include a vertical wall at the end of the ledge or any other type of height increasing structure. The ledge portion may even have a greater inclination than 90°, forming a sharp-angled end face. 
     According to at least one exemplary embodiment, each one of said first and second ledges comprises a disc plate receiving surface, wherein the disc plate receiving surface is inclined relative to the geometrical centre axis. Thus, although in some exemplary embodiments the entire first and second ledges may be inclined, suitably at least the surface portions that actually are in contact with the disc plates are inclined. 
     According to at least one exemplary embodiment, said inclined ledge portion forms part of said inclined disc plate receiving surface. The inclination of the disc plate receiving surface or the inclination of the inclined ledge portion may be straight or curved or even have a stepwise inclination, as long as it presents an axial stop to the inner periphery of the mating disc plate. 
     According to at least one exemplary embodiment, each one of the first and second ledges comprises a connected end and a free end, wherein the disc plate receiving surface extends between the connected end and the free end, wherein the disc plate receiving surface at the free end is located at a greater distance from the geometrical centre axis than the disc plate receiving surface at the connected end. Thus, the ledge may suitably taper towards the from the free end to the connected end. The thickness of the ledge may, for instance, be thicker at the free end than at the connected end. 
     According to at least one exemplary embodiment, for each one of the first and second disc plates, said inner periphery has a taper in a direction from the disc body facing surface towards the wear surface, wherein the respective disc plate receiving surface is inclined with the same angle as said taper. Thus, the inclined ledge mating with the inner periphery will act as a stop against the inner periphery of the disc plates, stopping the disc plates from becoming inadvertently loosened from the central disc body. Any appropriate angle of inclination may be chosen, suitably between 0° and 90°. It should be noted that although it is advantageous to have the same or substantially angle of taper on the disc plate receiving surfaces of the ledges as on said inner periphery of the first and second disc plates, respectively (thus making use of a large contact interface), in some exemplary embodiments it is conceivable to have a slightly different angle of taper between the surfaces of the ledge and the inner peripheries of the first and second disc plates (for example to achieve a slight wedging effect). 
     According to at least one exemplary embodiment, the brake further comprise an enveloping sleeve releasably secured to an outer circumference of the central disc body so as to apply a radially inwardly directed pressure to the first and second disc plates. By the provision of an enveloping sleeve, the disc plates can be further secured to the central disc body, without using screws or bolts extending through the wear surface of the disc plates. Thus, instead of holding the disc plates at their wear surface, the enveloping sleeve may apply a holding force at their outer peripheral surface. By simply removing the enveloping sleeve (which may, for instance, be attached to the outer circumference of the central disc body by means of snap fit, screws, bolts or other suitable means), worn disc plates may conveniently be replaced without needing to replace the entire brake disc arrangement, and thereafter the enveloping sleeve may be re-attached. 
     According to at least one exemplary embodiment, the enveloping sleeve covers the first and the second disc plates. In some exemplary embodiments the enveloping sleeve may cover the entire circumferential surface of the respective disc plate (i.e. the whole width/thickness of the disc plate), while in other exemplary embodiments the enveloping sleeve covers part of the circumferential surface (for example a part of the width/thickness of the disc plate which is closest to the central disc body). By covering the first and second disc plates, a simple and efficient solution is provided for holding the disc plates. However, it should be understood that in other exemplary embodiments, it may be conceivable to apply the holding force indirectly from the enveloping sleeve only covering the central disc body, via some other component or components to the disc plates. 
     In line with the previous discussions, according to at least some exemplary embodiments, the width of the enveloping sleeve is greater than the width of the outer circumference of the central disc body. Thus, the enveloping sleeve may suitably extend at least partly over the disc plates. According to at least one exemplary embodiment, the width of the enveloping sleeve is greater than the width of the outer circumference of the central disc body, wherein the enveloping sleeve covers the first and the second disc plates. 
     According to at least one exemplary embodiment, the enveloping sleeve forms a circle around the outer circumference of the central disc body. Although it is conceivable to, in at least some exemplary embodiments, have an enveloping sleeve which does not necessarily present a complete circle, a more uniform force distribution and retention capacity may be achieved if the enveloping sleeve forms a complete circle. 
     According to at least one exemplary embodiment, the enveloping sleeve comprises a circular central portion flanked on either side by two edge portions extending from the central portion to a respective edge, wherein each one of the edge portions has a mating surface for mating with said outer periphery of the first and second disc plates, respectively, wherein each one of the mating surfaces are inclined relative to the geometrical centre axis. This is advantageous since, this will further counteract axial movement of the disc plates relative to the central disc body, since these inclined surfaces form an extra axial stop. Again, axial movement of the disc plates are prevented without using bolts or screws inserted through the wear surfaces of the disc plates. Of course, instead of or in addition to said inclination of said mating surfaces, other means are also conceivable for counteracting axial movement of the disc plate relative to the central disc body. For instance, in some exemplary embodiments, the disc body facing surface of the disc plates and the central disc body may be provided with mutually cooperating engagement means. In some exemplary embodiments, the enveloping sleeve (or a component attached to the enveloping sleeve) may be provided with fixation means (such as screws or rivets) which may be inserted through the outer circumference of central disc body and the disc plates in order to axially fixate the disc plates relative to the central disc body. 
     According to at least on exemplary embodiment, said outer periphery tapers in a direction from the disc body facing surface towards the wear surface, wherein said mating surfaces of the enveloping sleeve has the same angle of taper as said outer periphery of the first and second disc plates, respectively. Any appropriate angle of inclination may be chosen, suitably between 0° and 90°. It should be noted that although it is advantageous to have the same or substantially angle of taper on the mating surfaces as on said outer periphery of the first and second disc plates, respectively (thus making use of a large contact interface), in some exemplary embodiments it is conceivable to have a slightly different angle of taper between the mating surfaces and the outer peripheries of the first and second disc plates (for example to achieve a slight wedging effect). 
     According to at least one exemplary embodiment, the brake disc further comprises a connecting member, such as a pin, for preventing rotation of the disc plates relative to the central disc body, the connecting member extending from the first disc plate, through a passage in the central disc body, to the second disc plate, wherein the connecting member extends into each one of the first and second disc plates. The connecting member may suitably be resilient (compressible and expandable) in the radial direction such that it presses against the passage walls and is firmly kept in place. The connecting member should suitably not extend all the way to the wear surface as that would risk similar problems as with the prior art in which screws or bolts were applied at the wear surface of the disc plates. Suitably, the connecting member extends just short of the thickness at which the disc plate would be replaced due to wearing. For instance, if the disc plate is intended to be replaced when half its thickness have worn off, then the connecting member would be configured to extend from the central disc body into the disc plate no more than half the thickness of the disc plate. 
     According to at least one exemplary embodiment each one of the first and second disc plates comprises a cavity for housing a respective end of the connecting member. The cavity may suitably be a through-hole for facilitating the insertion of the connecting member and later on the removal of the connecting member when the time has come to replace the disc plates. 
     According to at least one exemplary embodiment, said passage through the central disc body has a cross-sectional area which substantially corresponds to the cross-sectional area of the connecting member. Suitably, if said connecting member is resilient (compressible/expandable) the cross-sectional area of the connecting member may in a relaxed state be larger than the cross-sectional area of the said passage. In such case, the connecting member is compressed when inserted through the passage, and will then strive to resume its initial relaxed state, thus expanding against the passage walls. 
     According to at least one exemplary embodiment, said connecting member is a first connecting member and said passage is a first passage, wherein the brake disc further comprises at least a second connecting member extending from the first disc plate, through at least a second passage in the central disc body, to the second disc plate. Thus, there may be provided a plurality of connecting members, such as pins, for example resilient pins, which may be provided in respective passages to increase the strength of preventing the first and second disc plates to rotate relative to the central disc body. 
     Said second connecting member may suitably be connected to the first and second disc plates and to the central disc body at a shorter radial distance from the geometrical centre axis of the brake disc than the first connecting member. The plurality of connecting members may suitably be distributed in both the radial direction and the circumferential direction, or in only one of said directions. According to at least one exemplary embodiment, said first connecting member is one of a plurality of first connecting members and said first passage is one of a plurality of first passages, wherein each one of said plurality of first connecting members extends from the first disc plate, through a respective first passage in the central disc body, to the second disc plate, wherein said plurality of first connecting members are distributed along a first geometrical circle. According to at least one exemplary embodiment, said second connecting member is one of a plurality of second connecting members and said second passage is one of a plurality of second passages, wherein each one of said plurality of second connecting members extends from the first disc plate, through a respective second passage in the central disc body, to the second disc plate, wherein said plurality of second connecting members are distributed along a second geometrical circle, wherein the second geometrical circle is encircled by the first geometrical circle. According to at least one exemplary embodiment, each one of said plurality of first connecting members along the first geometrical circle is paired with a corresponding one of said plurality of second connecting members along the second geometrical circle, such that the first and second connecting members of each pair are located on a common radius. A symmetric distribution may be advantageous for the sake of good stability of the assembly. 
     According to at least one exemplary embodiment, the central disc body is provided with a plurality of passages for receiving a respective connecting member, wherein each one of the first and second disc plate has a plurality of holes, wherein the distribution pattern of said plurality of holes corresponds to the distribution pattern of said plurality of passages. 
     It should be understood that the above exemplified one or more connecting members for preventing rotation of the disc plates relative to the central disc body, are just one of several conceivable examples to achieve that effect. In other exemplary embodiments, the prevention against rotation may be achieved by mutually cooperative structures, such as for instance one or more protrusions and/or recesses in the central brake disc which are configured to engage with matching recesses and/or protrusions, respectively at the disc body facing side of the each disc plate. 
     Although the enveloping sleeve may advantageously be used for holding a complete disc plate, in some exemplary embodiments, it would be conceivable that each one of the first disc plate and the second disc plate comprises two or more disc plate segments which are separable from one another, wherein said wear surface is provided on each disc plate segment. In such case, the total number of connecting members is suitably at least equal to the number of disc plate segments for one of the first and second disc plates. It is also conceivable to have such disc plate segments in embodiments without the enveloping sleeve, in which case individual holding means, such as peripheral clamps may be used. Thus, according to at least some exemplary embodiments, each one of said first and second disc plates comprises two or more disc plate segments. Using a plurality of separate disc plate segments which together make up a complete disc plate when mounted to the central disc body may facilitate mounting the disc plates to central disc body. 
     According to at least some exemplary embodiments, the enveloping sleeve comprises two or more enveloping sleeve segments. Thus, the separate enveloping sleeve segments together make up a complete enveloping sleeve when mounted to the central disc body. Using a segmented enveloping sleeve may be advantageous for facilitating the mounting of the enveloping sleeve, in particular if the enveloping sleeve and the outer peripheries of the disc plates have inclined surfaces. However, it should be understood that a segmented enveloping sleeve may also be used in connection with non-inclined surfaces 
     According to at least one exemplary embodiment, the brake disc may comprise cooling channels for allowing circulation of air there through. Such cooling channels may, for instance, be provided in the central disc body. Alternatively, or additionally, cooling channels may be provided between the central disc body and the first and second disc plates. 
     According to a second aspect of the invention, the object is achieve by a vehicle comprising a brake disc according to the first aspect, including any embodiments thereof. The advantages of the second aspect are largely analogous with the advantages of the first aspect. 
     Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. 
       In the drawings: 
         FIG.  1    illustrates a vehicle, in accordance with at least one exemplary embodiment of the invention. 
         FIG.  2    illustrates a brake disc according to at least one exemplary embodiment, mounted on a wheel end hub. 
         FIG.  3    illustrates an exploded view of the brake disc in  FIG.  2   . 
         FIG.  4    illustrates a cross-sectional view of the brake disc in  FIG.  2   . 
         FIG.  5    is an enlarged view of part of  FIG.  4   . 
         FIG.  6    illustrates a brake disc according to at least another exemplary embodiment, mounted on a wheel end hub. 
         FIG.  7    illustrates an exploded view of a brake disc according to at least a further exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION 
       FIG.  1    illustrates a vehicle  1 , in accordance with at least one exemplary embodiment of the invention. Although the vehicle  1  is illustrated in the form of a truck, other types of vehicles, such as busses, construction equipment, trailers or passenger cars may be provided in accordance with the invention. 
     The truck (vehicle) comprises a cab  2  in which a driver may operate the vehicle  1 . The vehicle  1  comprises a number of road wheels  4 , herein illustrated as two pairs of wheels, however in other embodiments there may be a different number of wheels, such as three pairs, four pairs or more. In the cab  2  a driver may press a brake pedal with his/her foot in order to activate the brake or brakes. Activation of the brake causes brake pads to be pressed against an inventive brake disc (not illustrated in  FIG.  1   ) connected via a wheel end hub to an axle that rotates the road wheels  4 . 
       FIG.  2    illustrates a brake disc  10  according to at least one exemplary embodiment, mounted on a wheel end hub  20 .  FIG.  3    illustrates an exploded view of the brake disc  10  in  FIG.  2   .  FIG.  4    illustrates a cross-sectional view of the brake disc  10  in  FIG.  2   .  FIG.  5    is an enlarged view of  FIG.  4   . The brake disc  10  is configured to be connected via the wheel end hub  20  to a vehicle axle (not illustrated) and to be squeezed between brake pads (not illustrated). 
     With reference to  FIGS.  2 - 5    and, for explanatory reasons in particular with reference to the exploded view of  FIG.  3   , the brake disc comprises a central disc body  30  having a first side  32  and a second side  34  (see  FIGS.  4  and  5   ). The second side  34  faces in the opposite direction compared to the first side  32 . The brake disc  10  comprises a first disc plate  36  and a second disc plate  38 , each disc plate  36 ,  38  having a wear surface  40  for producing friction when a brake pad is pressed against the wear surface  40 . The wear surfaces  40  face away from the central disc body  30 . Each disc plate also has an oppositely facing, i.e. a disc body facing surface  42 . In the exploded view of  FIG.  3   , the wear surface  40  of the first disc plate  36  and the disc body facing surface  42  of the second disc plate  38  are visible. 
     The first disc plate  36  is releasably secured to the first side  32  of the central disc body  30  and the second disc plates  38  is releasably secured to the second side  34  of the central disc body  30 . When the first and second disc plates  36 ,  38  have been sufficiently worn out, they may easily be replaced with new disc plates, without needing to dismount the central disc body  30  from the wheel end hub  20 . An enveloping sleeve  50  may be releasably secured to an outer circumference  52  (see  FIG.  3   ) of the central disc body  30  so as to apply a radially inwardly directed pressure to the first and second disc plates  36 ,  38 . The enveloping sleeve  50  may be replaced by other peripherally applied means, such as clamps for supporting the disc plates  36 ,  38 . 
     The central disc body  30  is substantially circular and ring-shaped having a central opening through which the wheel end hub  20  may protrude. The central disc body  30  will thus be supported by the wheel end hub  20 , while the removable disc plates  36 ,  38  are or will be mounted to the central disc body  30 . The central disc body  30  may suitably be provided with cooling channels to allow air to circulate and cool the brake disc  10 . In  FIG.  3    cooling channel apertures  54  are visible on the radially outer circumference  52  of the central disc body  30 . Said radially outer circumference  52  may also be referred to as the radially outer periphery of the central disc body  30 . In this connection, it should be noted that the brake disc  10  has a geometrical centre axis x around which it rotates with the wheel axle. The geometrical centre axis x may thus also be referred to as a rotational axis. Radial directions are thus directions running perpendicularly away from the geometrical centre axis x. Circumferential directions run around the geometrical centre axis x. Axial directions extend along or in parallel with the geometrical centre axis x. In the cross-sectional view of  FIG.  4   , cooling channel apertures  54  are visible at the radially inner periphery  56  of the central disc body  30 . 
     As best seen in  FIG.  3   ,  FIG.  4    and  FIG.  5    the central disc body  30  may be provided with a plurality of passages  58  in the form of through holes which extend all the way from the first side  32  of the central disc body  30  to the second side  34  of the central disc body  30 . The function of the passages  58  will be explained further down in this description. As can be seen in  FIG.  3   , the plurality of passages  58  are distributed along two concentric imaginary circles, and are arranged in pairs along radii in different radial directions from the geometrical centre axis. Thus, each passage  58  in the inner imaginary circle is paired along a radius from the geometrical centre axis with a passage  58  in the outer imaginary circle. It should be noted that in other embodiments the passages  58  may be distributed differently and need not be paired or distributed along imaginary circles. It should furthermore be noted that although a plurality of passages  58  are illustrated in the exemplary embodiments of the drawings, in other embodiments the number of such passages may be fewer, for example just one passage or even no passage at all. 
     The central disc body  30  has on each one of the first and second sides  32 ,  34  an annular ledge  60  near its inner periphery  56  at the central hole, for supporting the first and second disc plates  36 ,  38 , respectively (see  FIG.  3    and  FIG.  5   ). The two ledges  60  may be referred to as first and second ledges  60  for receiving the first and second disc plates  36 ,  38 , respectively. 
     In the drawings, each ledge  60  is illustrated as having a constant inclination from its free end  61  towards its connected end  63  at the central disc body  30  (see  FIG.  5   ). However, in other exemplary embodiments, it may suffice that only a portion of the respective ledge  60 , referred to as a ledge portion, is inclined relative to the geometrical centre axis for counter acting axial movement of the disc plates  36 ,  38  relative to the central disc body  30 . The inclined ledge portion may suitably be at free end  61  of the ledge  60 , and may for example have a straight cross-section of may have a curved cross-section. The inclination may even be such that the ledge portion forms a substantially perpendicular wall relative to the geometrical centre axis and/or the rest of the ledge  60 . 
     As illustrated in  FIG.  5   , wherein the disc plate receiving surface extends between the connected end and the free end, wherein the disc plate receiving surface at the free end  61  is located at a greater distance from the geometrical centre axis than the disc plate receiving surface at the connected end  63 . 
     Each one of the first and second disc plates  36 ,  38  has an inner periphery  80  (see  FIG.  3    and  FIG.  5   ) extending from the wear surface  40  to the disc body facing surface  42 . The inner periphery  80  may be tapered. The inner periphery  80  may suitably have a taper in a direction from the disc body facing surface  42  towards the wear surface  40 . As explained above, at least a portion of the mating ledge  60  (in the illustrated example embodiments, the entire mating ledge  60 ) of the central disc body  30  is inclined. Suitably, the inclination of the ledge  60  or ledge portion is such that it has the same angle as said taper of the inner periphery  80  of the disc plates  36 ,  38 . The ledge  60  on each side is thus adapted to receive said inner periphery  80  of a respective one of the disc plates  36 ,  38 . 
     Thus, it should be understood that the ledge  60  provides for numerous possibilities, alternatives and embodiments for counteracting axial movement of the releasably securable disc plates  36 ,  38  relative to the central disc body, without using screws or bolts extending through the wear surface  40  of the disc plates  36 ,  38 . 
     The first and second disc plates  36 ,  38  are also ring-shaped and thus the wheel end hub  20  will extend through the central hole of the first and second disc plates  36 ,  38  as well. The first and second disc plates  36 ,  38  may be made of any suitable friction material (metallic, ceramic, etc.) and/or may be provided with a coating surface providing appropriate frictional properties. As can be seen in  FIG.  3   , the first and second disc plates  36 ,  38  may be provided with a plurality of holes  62  having a distribution pattern which corresponds to the distribution pattern of the plurality of passages  58 . 
       FIG.  3    illustrates a plurality of connecting members  64  which are configured to be inserted into said passages  58  of the central disc body  30 , each connecting member  64  fitting into one of said passages  58 . As can be seen in  FIG.  4    and  FIG.  5   , the length of the connecting members  64  may be such that they extend partly into the holes  62  of the first and second disc plates  36 ,  38 , but preferably not to the wear surface  40  of the disc plates  36 ,  38 . Suitably, the length of the connecting members  64  is shorter than the acceptable wear thickness of the disc plates  36 ,  38 . Put differently, if the disc plates  36 ,  38  are envisaged to be replaced when they have worn down to a certain reduced thickness compared to their initial thickness, at such reduced thickness the connecting members  64  should still be short from the worn surface. The function of the connecting members  64  is to prevent relative rotation between the disc plates  36 ,  38  and the central disc body  30 . 
     In the illustrated embodiments, a first plurality of connecting members  64  extend in a first plurality of passages  58  which are distributed along an imaginary outer circle, and a second plurality of connecting members  64  extend in a second plurality of passages  58  which are distributed along an imaginary inner circle. Other patterns are of course also conceivable. 
     The connecting members  64 , which are herein illustrated as pins, may suitably be resilient in the radial direction. For instance, they may be compressed when inserted into the first and second disc plates  36 ,  38  and central disc body  30 , and then expand so as to provide a tight fit with the walls defining the passages  58  in the central disc body  30 . In some exemplary embodiments, said passages  58  through the central disc body  30  has a cross-sectional area which substantially corresponds to the cross-sectional area of the connecting members  64 . 
     It should be understood that the disc plates do not necessarily need to have through holes  62  for accommodating the ends of the connecting members  64 , it would also be conceivable to have blind bores extending from the disc body facing surface  42 . Thus, in a general sense, each one of the first and second disc plates  36 ,  38  may comprise one or more cavities for housing a respective end of the one or more connecting members  64 , regardless of the cavities being in the form of blind bores or through holes. 
     As can be seen in the drawings, in the illustrated exemplary embodiments, the width of the enveloping sleeve  50  is greater than the width of the outer circumference  52  of the central disc body  30 . Suitably, as seen in the drawings, the enveloping sleeve  50  covers the first and the second disc plates  36 ,  38 , i.e. its width substantially corresponds to the total width (or thickness) of the radially outer peripheries of the disc plates  36 ,  38  and the central disc body  30 . However, in other exemplary embodiments, the enveloping sleeve  50  may have a smaller width and only partly covering the width of the disc plates  36 ,  38 . In still other exemplary embodiments, the enveloping sleeve  50  may have an even smaller width wherein it may provide a force onto the disc plates  36 ,  38  via one or more other components which at least partly cover the outer peripheries of the disc plates  36 ,  38 . 
     The enveloping sleeve  50  has been illustrated as forming a complete circle around the outer circumference of the central disc body (and around the disc plates), although other configurations are conceivable. As best seen in  FIG.  3    and  FIG.  5   , the enveloping sleeve  50  has a circular central portion  70  flanked on either side by two edge portions  72  extending from the central portion  70  to a respective edge  74 . Each one of the edge portions  72  has a mating surface  76  for mating with the outer periphery  78  of the first and second disc plates  36 ,  38 , respectively (outer periphery  78  is indicated in  FIG.  3   ). Each one of the mating surfaces  76  are inclined relative to the geometrical centre axis for counteracting axial movement of the disc plates  36 ,  38  relative to the central disc body  30 . The angle of inclination may for instance be 5°-80° relative to the geometrical centre axis, for instance 10°-50°, such as 15°-30°. 
     In the illustrated embodiments, the thickness of each one of the edge portions  72  of the enveloping sleeve  50  increases from the central portion  70  towards the respective edge  74 . 
     The inclination of the mating surfaces  76  is such that it slopes towards the geometrical centre axis as it extends away from the central disc body  30 . Thus, for each one of said mating surfaces  76 , the distance between the geometrical centre axis and the mating surface  76  is relatively larger adjacent to the central portion  70  of the enveloping sleeve  50  and relatively smaller adjacent to the respective edge  74  of the enveloping sleeve  50 . 
     In a corresponding manner, the outer periphery  78  of each disc plate  36 ,  38  (which outer periphery  78  extends from the wear surface  40  to an oppositely located disc body facing surface  42 ) tapers in a direction from the disc body facing surface  42  towards the wear surface  40 , wherein said mating surfaces  76  of the enveloping sleeve  50  has the same angle of taper as said outer periphery  78  of the first and second disc plates  36 ,  37 , respectively. 
     The enveloping sleeve  50  may be secured by fastening means to the central disc body. For instance, as illustrated in the exemplary embodiment of  FIG.  6   , the fastening means  82  may be or may comprise bolts, screws of rivets, which may be loosened when the enveloping sleeve is to be removed so as to allow replacement of worn disc plates. However, in other exemplary embodiments, the fastening means may not be visible from the outside, such as for instance in the form of mutually cooperating snap fit portions on the enveloping sleeve and the central disc body, respectively (this may for instance be the case in  FIG.  2   ). In other exemplary embodiments, there is no need for any particular fastening means, the enveloping sleeve my form a very tight fit with the central disc body and the disc plates, for instance providing a radially inward pressure of the disc plates towards the inclined ledge  60  to counteract axial movement of the disc plates relative to the central disc body. 
     As also illustrated in the exemplary embodiment of  FIG.  6   , the number of connecting members, passages and holes may be different in different embodiments. In  FIG.  6   , for instance, only one hole  62  is shown for inserting a single connecting member into one passage of the central disc body. It should thus be understood that features from any one of the herein described embodiments, whether discussed under the heading “Summary” or under the heading “Detailed Description of Example Embodiments of the Invention”, may as long as they are compatible, be freely adapted to and implemented in any other one of the exemplary embodiments. For instance, the fastening means  82  in the exemplary embodiment of  FIG.  6    may be implemented for the brake disc  10  in the exemplary embodiment of  FIG.  2   . 
       FIG.  7    illustrates an exploded view of a brake disc according to at least a further exemplary embodiment. This embodiment has most features in common with the exemplary embodiment of  FIG.  3   , and therefore, common features are represented by the same reference numerals. 
     In the exemplary embodiment of  FIG.  7    the first disc plate  36  is made up by three separate disc plate segments  36   a,    36   b,    36   c,  which may be individually mounted to the central disc body  30 . Once mounted, they make up the complete first disc plate  36 . Similarly the second disc plate  38  is made up by three separate disc plate segments  38   a,    38   b,    38   c,  which may be individually mounted to the central disc body  30 . Using a plurality of disc plate segments (i.e. two or more disc plate segments) to make up a complete disc plate may facilitate the mounting procedure. 
       FIG.  7    also illustrates a segmented enveloping sleeve  50 . The enveloping sleeve  50  is made up by three separate enveloping sleeve segments  50   a,    50   b,    50   c,  which may be individually mounted to the outer circumference  52  of the central disc body  30 . Once mounted, they make up the complete enveloping sleeve  50 . Using a plurality of enveloping sleeve segments (i.e. two or more enveloping sleeve segments) to make up a complete enveloping sleeve may facilitate the mounting procedure. 
     It should be understood that the segmented disc plates  36 ,  38  and the segmented enveloping sleeve  50  shown in  FIG.  7   , may in other exemplary embodiments be combined with other features than illustrated in  FIG.  7   . For instance, according to at least some exemplary embodiments, the brake disc may comprise segmented first and second disc plates, and a non-segmented enveloping sleeve, such as the enveloping sleeves illustrated in the previously discussed drawing figures. Likewise, according to at least some exemplary embodiments, the brake disc may comprise a segmented enveloping sleeve and non-segmented first and second disc plates, such as the disc plates illustrated in the previously discussed drawing figures. The number of connecting members  64 , passages  58  and holes  62  may also be different than illustrated in  FIG.  7   . For instance, in some exemplary embodiment there may be only one connecting member for each pair of disc plate segments. 
     It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.