Patent Publication Number: US-2006014600-A1

Title: Lightweight drive chain

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The invention relates to a drive chain, more particularly to a lightweight drive chain.  
      2. Description of the Related Art  
      Referring to  FIGS. 1 and 2 , a conventional drive chain  1  includes a plurality of parallel pairs of inner chain plates  11 , a plurality of parallel pairs of outer chain plates  12 , a plurality of pins  14 , and a plurality of tubular rollers  13 . Each pair of the inner chain plates  11  is disposed between two adjacent pairs of the outer chain plates  12 . Each of the inner chain plates  11  has a pair of inner end portions  111  spaced apart from each other, and each of the outer chain plates  12  has a pair of outer end portions  121  spaced apart from each other. The pins  14  connect the inner chain plates  11  to the outer chain plates  12  by passing through the inner end portions  111  and the corresponding outer end portions  121 .  
      It is desirable to reduce the overall weight of the drive chain for efficient use of power without sacrificing the structural integrity of the drive chain. Furthermore, it is desirable to reduce the contact areas of the inner and outer chain plates  11 , 12  to avoid dirt accumulation therebetween, which can result in abrading of the inner and outer chain plates  11 , 12  that can lead to a shorter service life for the drive chain  1 .  
     SUMMARY OF THE INVENTION  
      Therefore, the object of the present invention is to provide a drive chain, which is relatively lightweight as compared to the conventional drive chain.  
      Accordingly, the lightweight drive chain of this invention includes a plurality of parallel pairs of outer chain plates, a plurality of parallel pairs of inner chain plates, and a plurality of pins.  
      Each pair of the inner chain plates is disposed between two adjacent pairs of the outer chain plates. The pins connect the inner chain plates to the outer chain plates.  
      Each of the outer chain plates has a first inner surface, a first outer surface opposite to the first inner surface, a pair of first end portions spaced apart from each other along a first longitudinal axis, a first connecting portion interconnecting the first end portions along the first longitudinal axis, and a pair of first pin holes that are formed respectively in the first end portions and that extend through the first inner and outer surfaces. Each of the first pin holes is defined by a first hole periphery.  
      Each of the inner chain plates has a second outer surface, a second inner surface opposite to the second outer surface, a pair of second end portions spaced apart from each other along a second longitudinal axis, a second connecting portion interconnecting the second end portions, and a pair of second pin holes that are formed respectively in the second end portions and that extend through the second inner and outer surfaces.  
      Each of the outer chain plates further has a pair of first weight-reducing slots, each of which extends radially from the first hole periphery of a respective one of the first pin holes. The first weight-reducing slots are not in spatial communication with each other.  
      Each of the inner chain plates further has a second weight-reducing slot disposed between the second pin holes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:  
       FIG. 1  is a fragmentary side view of a conventional drive chain;  
       FIG. 2  is a fragmentary partly cross-sectional schematic view of the conventional drive chain;  
       FIG. 3  is a fragmentary side view of the preferred embodiment of the lightweight drive chain according to this invention;  
       FIG. 4  is a fragmentary cross-sectional schematic view of the preferred embodiment;  
       FIG. 5  is a side view of an outer chain plate used in the preferred embodiment;  
       FIG. 6  is a sectional view of the outer chain plate taken along line  6 - 6  of  FIG. 5 ; and  
       FIG. 7  is a side view of an inner chain plate used in the preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIGS. 3 and 4 , the preferred embodiment of the lightweight drive chain  2  according to this invention is shown to include a plurality of parallel pairs of outer chain plates  3 , a plurality of parallel pairs of inner chain plates  4 , a plurality of pins  22 , and a plurality of tubular rollers  21 . Each pair of the inner chain plates  4  is disposed between two adjacent pairs of the outer chain plates  3 . The pins  22  connect the inner chain plates  4  to the outer chain plates  3 . Each of the pins  22  is tubular in this embodiment.  
      Referring to  FIGS. 4, 5 , and  6 , each of the outer chain plates  3  is made of metal, and has a first inner surface  31 , a first outer surface  32  opposite to the first inner surface  31 , a pair of first end portions  33  spaced apart from each other along a first longitudinal axis (X), a first connecting portion  34  interconnecting the first end portions  33  along the first longitudinal axis (X), and a pair of first pin holes  35  that are formed respectively in the first end portions  33  and that extend through the first inner and outer surfaces  31 , 32 . Each of the first pin holes  35  is defined by a first hole periphery  351 . Each of the outer chain plates  3  further has a pair of first weight-reducing slots  36 , each of which extends radially from the first hole periphery  351  of a respective one of the first pin holes  35 . Preferably, each of the first weight-reducing slots  36  extends along the first longitudinal axis (X) toward the first connecting portion  34 . The first weight-reducing slots  36  are not in spatial communication with each other so as not to weaken undesirably the outer chain plates  3 .  
      In this embodiment, each of the first weight-reducing slots  36  has an open end portion  361  at the first hole periphery  351  of the respective one of the first pin holes  35 , a closed end portion  362  opposite to the open end portion  361 , and an intermediate expanded portion  363  between the open and closed end portions  361 , 362 . Each of the first weight-reducing slots  36  has a width that is reduced from the intermediate expanded portion  363  to each of the open and closed end portions  361 , 362 . The open end portion  361  has an opening  365  smaller than a diameter (D) of the respective one of the first pin holes  35  and smaller than a largest width at the intermediate expanded portion  363 . Each of the first pin holes  35  has a center  352 . The opening  365  of the open end portion  361  of each of the first weight-reducing slots  36  defines an angle (β) ranging from 30 to 60 degrees with respect to the center  352  of the respective one of the first pin holes  35 .  
      Each of the first end portions  33  is formed with two reinforcing ribs  331  that protrude from the first outer surface  32 , that are radially offset from the first pin hole  35 , and that are disposed on opposite sides of the first longitudinal axis (X). Each of the reinforcing ribs  331  forms an acute angle (a) with respect to the first longitudinal axis (X). Preferably, the acute angle is 45 degrees. The reinforcing ribs  331  are formed by punching at the first inner surface  31  such that the first inner surface  31  is formed with recesses  332  corresponding to the reinforcing ribs  331 .  
      Preferably, the first connecting portion  34  is formed with an inclined primary reinforcing ridge  341  that protrudes from the first outer surface  32  and that is inclined with respect to the first longitudinal axis (X). The primary reinforcing ridge  341  is formed by punching at the first inner surface  31  such that the first inner surface  31  is formed with a primary groove  341 ′ corresponding to the primary reinforcing ridge  341 . The first connecting portion  34  is further formed with an inclined secondary reinforcing ridge  342  that crosses the primary reinforcing ridge  341  and that protrudes from the first outer surface  32  at a distance less than that of the primary reinforcing ridge  341  as best shown in  FIG. 6 . The secondary reinforcing ridge  342  is likewise formed by punching at the first inner surface  31  such that the first inner surface  31  is formed with a secondary groove  342 ′ corresponding to the secondary reinforcing ridge  342 .  
      Referring to  FIGS. 4 and 7 , each of the inner chain plates  4  has a second outer surface  41 , a second inner surface  42  opposite to the second outer surface  41 , a pair of second end portions  43  spaced apart from each other along a second longitudinal axis (Y), a second connecting portion  44  interconnecting the second end portions  43 , and a pair of second pin holes  45  that are formed respectively in the second end portions  43  and that extend through the second inner and outer surfaces  42 , 41 . Each of the inner chain plates  4  further has a second weight-reducing slot  46  disposed between the second pin holes  45 . The second weight-reducing slot  46  is formed in the second connecting portion  44 , extends along the second longitudinal axis (Y), and is not in spatial communication with either of the second pin holes  45  so as not to weaken undesirably the inner chain plates  4 . The maximum width (W) of the second weight-reducing slot  46  is smaller than a diameter (D′) of each of the second pin holes  45 .  
      Each of the second pin holes  45  is defined by a second hole periphery  451 . Each of the inner chain plates  4  further has a pair of annular flanges  47  protruding from the second inner surface  42  at the second hole periphery  451  of a respective one of the second pin holes  45 .  
      Each of the tubular rollers  21  is sleeved rotatably on a confronting pair of the annular flanges  47  of a corresponding parallel pair of the inner chain plates  4 .  
      In view of the aforesaid, the following effects can by achieved by the lightweight drive chain of this invention:  
      1). Each of the outer chain plates  3  is formed with a pair of the first weight-reducing slots  36 . Each of the inner chain plates  4  is formed with the second weight-reducing slot  46 . Each of the pins  22  is tubular. Therefore, the overall weight of the drive chain  2  of this invention can be substantially reduced as compared to the conventional drive chain  1 .  
      2) Each of the first end portions  33  of each of the outer chain plates  3  is formed with two reinforcing ribs  331 . The first connecting portion  34  of each of the outer chain plates  3  is formed with the primary and secondary reinforcing ridges  341 , 342 . Furthermore, the reinforcing ribs  331  are formed at positions where breaking of a conventional outer chain plate are likely to occur. Therefore, the structural strength of each of the outer chain plates  3  can be reinforced.  
      3) Although each of the first weight-reducing slots  36  is in spatial communication with a corresponding one of the first pin holes  35 , the opening  365  of the open end portion  361  of each of the first weight-reducing slots  36  defines the angle (β) ranging from 30 to 60 degrees, which can prevent each of the pins  22  from moving into a corresponding one of the first weight-reducing slots  36 .  
      4) The overlapping area between the first end portions  33  of the outer chain plates  3  and the adjacent second end portions  43  of the inner chain plates  4  is reduced, thereby minimizing dirt accumulation therebetween.  
      5) Each of the tubular rollers  21  is sleeved rotatably on a confronting pair of the annular flanges  47  of a corresponding parallel pair of the inner chain plates  4 , which further reinforces the structural strength of the drive chain  2 .  
      While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.