Patent Publication Number: US-2006005903-A1

Title: Non-pneumatic wheel

Description:
FIELD OF THE INVENTION  
      The present invention is directed to a non-pneumatic wheel. More specifically, the present invention is directed to a covering, or tread package, for a non-pneumatic wheel and the mounting rim upon which the tread package is mounted.  
     BACKGROUND OF THE INVENTION  
      Non-pneumatic wheels are well known and conventional. Such wheels have been used in numerous conditions and situations; the use being as diverse as mining operations to spare tires.  
      Additionally, various tread, or track-like, coverings for contact with road surfaces have been known in the art, such as those disclosed in U.S. Pat. No. 2,142,315 (Hershey), U.S. Pat. No. 3,149,656 (Johnson), and U.S. Pat. No. 3,326,261 (Young). Hershey discloses a replaceable covering for a tire. The covering has a pair of extending flanges having therein metal rings. Johnson discloses a renewable tread wherein the tread fits into slots on the tire casing. Young discloses a retreading operation wherein the carcass is buffed down and provided with mechanical locking means to interact with the replacement tread. The replacement tread may be provided with a pair of flanges, each flange containing therein a continuous metal cord.  
      U.S. Pat. No. 5,450,887 (Habay) discloses a similar tread covering having metal reinforced edges similar to the previously noted patents. However, the tread of Habay is mounted on a rigid support, the rigid support being mounted in the interior of a pneumatic tire to provide support for the pneumatic tire in the event of reduced pressure operation.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a non-pneumatic wheel system designed for reduced weight and to eliminate flat tires during operation of the wheel. The invention has a mounting means, a tread support, and a tread. The tread is an annular article defined by opposing lateral edges and a ground contacting surface that forms the ground contacting means for the non-pneumatic wheel system. The internal construction of the tread includes a belt package, a primary reinforcement layer and a pair of hoop reinforcements in the lateral edges. The hoop reinforcements are located radially inward and axially outward of the ground contacting surface.  
      In one aspect of the invention, the primary reinforcement layer of the tread is a cord reinforced layer. The cords of the layer are inclined at an angle in the range of 0° to 15° relative to the circumferential direction of the tread. The material forming the cords may be steel, aramid, and nylon.  
      In another aspect of the invention, the ground contacting surface of the tread has a defined width W. The primary reinforcement layer is a cord reinforced layer and has an axial width WR between the outermost reinforcing cords. The width WR of the primary reinforcing layer is preferably less than the width W of the ground contacting surface.  
      In another aspect of the invention, in the tread, the belt package is located radially outward of the primary reinforcing layer, and is comprised of at least two layer of cord reinforced ply.  
      In another aspect of the invention, in the tread, the hoop reinforcements are located radially inward of the primary reinforcing layer. The hoop reinforcements may be enveloped by elastomeric chipper layers.  
      In another aspect of the invention, the tread support is an annular article defined by opposing lateral edges. The tread support has a central rim upon which the tread is positioned and mounting wells at each lateral edge. When the tread is placed on the tread support, the hoop reinforcements of the tread sit within the mounting wells.  
      In another aspect of the invention, the mounting wells of the tread support may be either continuous or discontinuous along the annular length of the tread support.  
      In another aspect of the invention, the tread support also has a flange located at the axially outer side of each mounting well. The flanges may be continuous or discontinuous and also may be integrally formed with the tread support or mechanically secured to the tread support.  
      The present invention may also be characterized by the relationship of the internal components of the tread. In that aspect of the invention, the non-pneumatic wheel system has the following components: a mounting means, a tread support, and a tread. The tread has a belt package, a primary reinforcement layer and a pair of hoop reinforcements in the lateral edges. The hoop reinforcements of the tread are located radially inward and axially outward of the primary reinforcement layer.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will be described by way of example and with reference to the accompanying drawings in which:  
       FIG. 1  is a cross sectional view of a portion of a non-pneumatic wheel;  
       FIG. 2  is a perspective cut view of the tread;  
       FIG. 3  is a forward view of the tread support;  
       FIG. 4A  is an alternative embodiment of the tread support; and  
       FIG. 4B  is side view of the tread support of  FIG. 4A . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The following language is of the best presently contemplated mode or modes of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. The reference numerals as depicted in the drawings are the same as those referred to in the specification. For purposes of this application, the various embodiments illustrated in the figures each use the same reference numeral for similar components. The structures employed basically the same components with variations in location or quantity thereby giving rise to the alternative constructions in which the inventive concept can be practiced.  
       FIG. 1  illustrates a non-pneumatic wheel in accordance with the present invention. The wheel has three primary elements: the mounting means or wheel center  10 , the tread support or rim  12 , and the track or tread  14 . The tread support  12  is fixedly secured to the mounting means  10 ; either being formed integrally with the mounting means  10  or being mechanically secured to the mounting means  10 . The tread  14  is mounted onto the tread support  12  and establishes a ground contact surface for the non-pneumatic wheel. The entire radially inner surface of the tread  14  contacts the tread support  12 .  
      The tread  14 , shown in cut-away section in  FIG. 2 , is a unitary annular article and has a ground contacting surface  16 . The ground contacting surface  16  has opposing lateral edges  18 ,  20 . The ground contact surface  16  is shown with no surface features; however, any groove or tread pattern may be provided. The ground contacting surface  16  has a width W. Radially inward of the ground contacting surface  16  is a belt package  22 . Radially inward of the belt package  22  is a primary reinforcement layer  24 . At the extreme lateral edges are hoop reinforcements  26 .  
      The belt package  22  has at least two cord reinforced layers  28 ,  30 . The radially inner layer  28  has an axial width greater than the radially outer layer  30 . The cords are formed of materials such as steel, aramid, nylon, polyester, cotton, and blends of these materials. The cords have a diameter in the range of 0.35 to 1.5 mm. The cords in each layer are inclined at angles of 10° to 45° relative to the circumferential direction of the belt package, with the cords in each layer being crossed relative to the cords in the adjacent layer.  
      The primary reinforcement layer  24  is located radially inward of the belt package  22 . The primary reinforcement layer  24  is comprised of at least a single layer of large diameter, low angle reinforcing cords  32 . The cords  32  have a diameter greater than the diameter of the cords in the belt package cord reinforced layers  28 ,  30 . The large diameter cords  32  enable the tread  14  to achieve a high tension between the tread  14  and the wheel  10 . A minimum of 100 lbs. of tension between the tread  14  and the wheel  10  is desired. The minimum tension for any non-pneumatic wheel according to the present invention is equal to the actual load that will be placed on the wheel. The diameter of the cords  32  is in the range of 1.4 mm to 7.6 mm. The cords are inclined at an angle in the range of 0° to 15° relative to the circumferential direction of the tread. The cords are formed from high modulus materials such as steel or aramid, or may be blended with other modulus materials such as nylon and polyester.  
      The axial width between the axially outermost cords  32  of the primary reinforcement layer  24  define the axial width WR of the primary reinforcing layer. The width WR is in the range of 85 to 130% of the axial width W of the ground contacting surface  16 .  
      Radially inward of the primary reinforcing layer may be a secondary belt package comprising at least one cord reinforced layer  36 . The layer  36  is formed of cords inclined at angles of zero to 5 degrees, relative to the circumferential direction of the tread  14 . The layer  36  has a variable axial width, and depending on the tension requirements of the tread  14 , the layer  36  may have a width greater or less than the axial width of the other belt package cord reinforcing layers  28 ,  30 .  
      Axially outward of the lateral tread edges  18 ,  20 , and radially inward of the ground contacting surface are hoop reinforcements  26 . The hoop reinforcements  26  are unitary circular articles, providing tension at the extreme edges of the tread  14  and assisting in holding the tread  14  to the tread support  12 . In a conventional pneumatic tire, the similar tire element, the tire beads, are inextensible hoops that aid in maintaining the tire on a wheel rim. Because a tire is provided with an internal air pressure, the tire beads are popped into place on the tire rim during inflation of the tire. Herein, there is no internal gas chamber for the non-pneumatic wheel, and thus no way to utilize gas pressure to pop the hoop reinforcements into place on the tread support.  
      To enable mounting of the tread  14 , the hoop reinforcements  26  may be extensible, or compliant, to permit the hoop reinforcements  26  to move into the wells  38  provided in the tread support  12 . For such an embodiment, the hoop reinforcements  26  must be extensible, but must also provide sufficient tension to hold the tread  12  taut. Alternatively, if the mounting means  10  and/or the tread support  12  are capable of collapsing and extending for purposes of mounting the tread  14  onto the tread support  12 , the hoop reinforcements  26  may be inextensible hoops similar to bead rings of a pneumatic tire.  
      The hoop reinforcements  26  may be formed from materials such as steel or textile, with applicable textile materials being nylon, aramid, rayon, polyester. When the hoop reinforcements  26  are formed from a more inextensible material, such as steel, and the hoop reinforcements  26  must be extensible to permit mounting, the inextensible material is treated or shaped in a manner to provide the hoop reinforcements  26  with a degree of compliance. This may be accomplished by introducing twists into the inextensible material as it is wound to form the hoop reinforcements  26 ; such twisting being done on a group of cords when forming the hoop reinforcement  26  or when forming individual cords that will be gathered in some manner to form the hoop reinforcements  26 . The required degree of compliance of the hoop reinforcement  26  may also vary depending upon the type of rim  12  being used and how the tread  14  is secured onto the rim, see further discussion below regarding rim variations.  
      The hoop reinforcements  26  have an overall diameter D, and are spaced apart from one another by an axial width WH, as measured from the axially innermost surface point of each hoop reinforcement  26 . The hoops  26  are illustrated as being circular in cross-sectional configuration, but may have any cross-sectional configuration, including triangular, oblong, or any rectilinear configuration. The actual cross-sectional configuration is dependent upon the required physical properties of the hoop reinforcements  26 .  
      In addition to the hoop reinforcements  26  being located radially inward of the ground contacting surface  26 , the hoop reinforcements  26  are located radially inward of the primary reinforcement layer  24 . To place the hoop reinforcements  26  radially inward of the primary reinforcement layer  24 , the hoop reinforcements are enveloped by an elastomeric layer  40  that extends between both hoop reinforcements  26 . The elastomeric layer  40  may or may not be cord reinforced. If the layer  40  is cord reinforced, the cords are inclined at an angle of 15 to 45 degrees relative to the circumferential direction of the tread  14 . To shape the lower edge of the tread  14  in the area of the hoop reinforcements  26 , the hoop reinforcements may be enveloped by an elastomeric chipper  42  and provided with a triangular insert  44 .  
      The tread support  12  is shown in cross-section in  FIG. 1  in combination with the mounting means  10  and the tread  14 , and by itself in  FIG. 3 . As noted already, the tread support  12  has mounting wells  38  at the axially outermost edges of the support  12 . Located between opposing mounting wells  38  is a central rim  46  which makes full contact with the radially inner side of the tread  14 . The wells  38  are formed by a support wall  48  and a flange  50 . The support wall  48  extends from the central rim  46  and is inclined at an angle a between 30° and 60° relative to the radial direction of the tread support  12 . In this illustrated embodiment, the wells  38  and the flange  50  are continuous around each lateral, or axial, edge of the tread support  12 .  
      In the tread support  12  of  FIGS. 4   a  and  4   b,  the mounting wells  38  are discontinuous about the circumferential lateral edges of the tread support  12 . The lateral edges of the tread support  12 , specifically the support walls  48 , are discontinuous. The support walls  48  are shown as having a sinusoidal edge configuration; however the support wall edges  52  may have any configuration, including triangular, octagonal, and hexagonal. To secure the edges of the tread  14  onto the tread support  12 , the discontinuous lateral edges are provided with intermittent flanges  50 . The flanges  50  may be provided at every location wherein there is a support wall  48  or may be provided in numbers sufficient to retain the tread  14  on the tread support  12 . In the illustrated embodiment, the flanges  50  are provided intermittently about the circumference of the tread support  12 , located at every third support wall  48 . Even with the discontinuous mounting wells  38 , the flanges  50  may be integrally formed with the support walls  48 , or may be formed separately and afterwards secured to the tread support  12 . Such securing means includes, but is not limited to, bolting, welding, or adhesively securing the flanges  50 . Similarly, for the continuous mounting wells  38  and flanges  50  of  FIG. 3 , the flanges may be separately formed and separately secured to the tread support  12 .  
      The present invention yields a lightweight, non-pneumatic alternative wheel. The structure of the tread and the tread support provide for easy assembly of the non-pneumatic wheel.