Patent Publication Number: US-2003221759-A1

Title: Multi-piece rim for pneumatic tire

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to a multi-piece rim assembly for mounting a pneumatic tire thereon, such as for use on a large industrial vehicle.  
       BACKGROUND OF THE INVENTION  
       [0002] A rim assembly mounting a tire on a large vehicle is normally formed from a plurality of separate pieces. Typically, the assembly is a five piece structure comprising a cylindrical rim base having opposed annular edges, a first side flange located against one of the annular edges of the rim base, a second side flange located at the other annular edge of the rim base, an annular bead seat band located between the rim base and the second side flange and a lock ring which engages with a lock ring recess in the rim base to lock the pieces together. The pneumatic tire is held in position between the side flanges. The loose side flanges are held in place against the annular edges of the rim base by the air pressure of the tire.  
       [0003] A problem that arises is that the side flanges tend to rotate relative to the rim base during rapid acceleration or deceleration due to torque input from the tire. This results in mechanical damage to the rim base and side flanges.  
       SUMMARY OF THE INVENTION  
       [0004] According to the invention there is provided a multi-piece rim assembly for a pneumatic tire comprising a substantially cylindrical rim base with opposite annular ends and a pair of side flanges at the opposite annular ends, wherein at least one of the flanges is shrink-fitted in position, thereby to counteract relative rotation between the flange and the rim base. Preferably both of the side flanges are shrink-fitted in position.  
       [0005] Also according to the invention there is provided a multi-piece rim assembly for a pneumatic tire, comprising a substantially cylindrical rim base with opposite annular ends; a first side flange located against one of the annular edges; a second side flange located at the other annular edge; and an annular bead seat band located between the second side flange and the rim base, wherein the second side flange is shrink-fitted around the bead seat band, thereby to counteract relative rotational movement between the second flange and the bead seat band. In a preferred embodiment, the first side flange is also shrink-fitted onto the rim base, thereby to counteract relative rotational movement between the first side flange and the rim base.  
       [0006] Also according to the invention there is provided a multi-piece rim assembly for a pneumatic tire, comprising a substantially cylindrical rim base having an annular end and a side flange located against the annular edge for containment of a tire mounted on the rim assembly, wherein the side flange is shrink-fitted onto the rim base, thereby to counteract relative rotational movement between the side flange and the rim base.  
       [0007] Further according to the invention there is provided a method of manufacturing a multi-piece rim assembly for a pneumatic tire, which rim assembly comprises a substantially cylindrical rim base with opposite annular ends and a pair of side flanges at the opposite annular ends, comprising the step of shrink-fitting at least one of the side flanges in position, thereby to counteract relative rotation between the flange and the rim base.  
       [0008] Also according to the invention there is provided a method of manufacturing a multi-piece rim assembly for a pneumatic tire, which rim assembly comprises a substantially cylindrical rim base with opposite annular ends; a first side flange located against one of the annular edges; a second side flange located at the other annular edge; and an annular bead seat band located between the second side flange and the rim base, comprising the step shrink-fitting the second flange around the bead seat band, thereby to counteract relative rotation movement between the second flange and the bead seat band. Preferably, the method further comprises the step of shrink-fitting the first side flange onto the rim base, thereby to counteract relative rotational movement between the first side flange and the rim base.  
       [0009] Also according to the invention there is provided a method of manufacturing a multi-piece rim assembly for a pneumatic tire, which rim assembly comprises a substantially cylindrical rim base having an annular end and a side flange located against the annular edge for containment of a tire mounted on the rim assembly, comprising the step of shrink fitting the side flange onto the rim base, thereby to counteract relative rotational movement between the side flange and the rim base.  
       [0010] Further objects and advantages of the invention will become apparent from the description of preferred embodiments of the invention below. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 shows a radial cross-section of a five piece rim assembly for a large industrial vehicle;  
     [0012]FIG. 2 is a cross-section similar to FIG. 1 but with part of the rim base omitted; and  
     [0013]FIG. 3 is a partial three-dimensional view of the parts shown in FIG. 2. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0014] In FIG. 1, reference numeral  4  generally indicates a five piece rim assembly comprising a cylindrical rim base  5  having opposed annular edges  6  and  7 ; a first side flange  14  located against the annular edge  6 ; a second side flange  17  located at the other annular edge  7 ; an annular bead seat band  11 ; and a lock ring  20  which engages with a lock ring recess  22  locking the assembly together.  
     [0015] As shown, the bead seat band  11  is inserted between the second side flange  17  and the rim base  5 .  
     [0016] The rim base  5  is conveniently manufactured from three separate parts, i.e. an annular rim back section  10 , an annular gutter section  8  and a cylindrical centre band or centre section  9 , to form a unitary structure.  
     [0017] In FIGS. 2 and 3, the disposition of the side flanges  14  and  17  with respect to the rim back section  10  and seat band  11 , respectively, is shown. A portion of a tire  30  that is mounted on the rim assembly  5  is shown in broken lines in FIG. 2.  
     [0018] In conventional rim assemblies, only friction force at interfaces  18 ,  19  (FIG. 2) opposes the torque input form the tire  30  on the side flanges  14 ,  17 . As a result, the flanges  14 ,  17  can rotate relative to the rim base  5  causing fretting damage to the interfaces  18 ,  19 .  
     [0019] According to the present invention, either one or both of the side flanges  14 ,  17  are manufactured having an inside diameter slightly less than the outside diameter of corresponding part of the rim base  5  or bead seat band  11  where the respective side flange  14 ,  17  will be located. These outside diameters are indicated at  24  and  26  in FIG. 1.  
     [0020] Prior to assembly, the flanges  14 ,  17  are heated. Due to thermal expansion the inside diameters of the flanges  14 ,  17  increase so that they can fit around the outside diameters  24  and  26 . As the flanges  14 ,  17  cool, they contract to form a tight shrink fit around the rim base  5 . In the resulting rim assembly  4 , the interference shrink fit counteracts rotation or spinning of the side flanges  14 ,  17  relative to the rim base  5 . In order to achieve a proper shrink fit, the inside diameters of the flanges  14  and  17  and the outside diameters  24  and  26  are machined for an accurate fit.  
     [0021] Either one or both of the flanges  14 ,  17  can be shrink fitted in this fashion.  
     [0022] Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.