Abstract:
The respective ends of a chain body composed of alternate inner and outer links are connected to form an endless loop by a connecting link comprising a first pair of connecting plates and a second pair of connecting plates. Two long connecting pins are secured to the second connecting plates. One of the long connecting pins is inserted through a long bushing, which extends through a spacer and is fixed to the first connecting plate. The other long connecting pin extends through a bushing extending through a pair of inner plates of an inner link at one end of the chain body, and spacers are provided between the inner plates and the second connecting plates. The resulting chain has an odd number of links, but lacks the weakness and susceptibility to breakage of conventional chains having odd numbers of links, utilizing offset plates.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a chain having an odd number of links, in which the chain comprises alternating inner links and outer links and is connected to form an endless loop by a connecting link.  
         BACKGROUND OF THE INVENTION  
         [0002]    In an endless chain composed of inner and outer links, each inner link typically has a pair of bushings fixed to a pair of inner plates. Each outer link is composed of a pair of outer plates to which a pair of connecting pins is secured. The inner and outer links are connected by inserting the connecting pins through the bushings of the inner links, so that the chain is composed of alternating inner and outer links. Such an endless chain is generally formed with an even number of links, because the loop is closed by connecting an inner link to an outer link.  
           [0003]    When an endless chain having an even number of links is engaged with a pair of sprockets for power transmission, since the sprocket mounting positions and the distance between the shafts of the sprockets will have already been determined, the chain is frequently not of suitable length. In such a case, the length of the chain is adjusted so that it has an odd number of links. Adjustment is accomplished by connecting an inner link at one end of the chain to an outer link at the other end of the chain through an offset link comprising a pair of plates each having portions that are offset from each other in the direction of the width of the chain. Because of the addition of the offset link, the chain has an odd number of links. The offset plates are usually formed with bent middle portions, and consequently have poor strength. Because of the bent middle portions of the offset plates, when tension is applied to the chain, the chain is liable to break.  
           [0004]    A well-known solution to the problem of weakening of the chain due to the bent offset plates, is to provide a reinforcing connecting plate on an outer sides of the offset plates in order to resist tension. This solution is described in registered Japanese utility model publication No. 3047191.  
           [0005]    [0005]FIG. 7 shows an example of a connecting portion of a chain connected by a conventional offset plate. The chain  31  comprises an even number of links in which inner plates  32  and outer plates  33  are connected to one another by pins  36 . To connect the chain links to obtain an endless chain comprising an odd number of links, the ends of chain are respectively connected to an offset link comprising an offset plate  37  and a bushing  35 .  
           [0006]    Each offset plate  37  includes a bent portion  37   a  in its middle portion, which connects an outer plate portion  37   b  at one end to an inner plate portion  37   c  at the other end. A pin hole  38  is formed in the outer plate portion  37   b , and a bushing hole  39  is provided in the inner plate portion  37   c . A reinforcing connecting plate  41  is provided on the outside of the offset plate  37 . A pin hole  42  is provided in one end portion of plate  41 , and a hole  44  for receiving a small bushing  43 , through which a pin  40  is inserted, is provided in the other end portion of plate  41 .  
           [0007]    Each end of the left-hand pin  36  in FIG. 7, is inserted through a bushing  35  fixed to the inner plates  32 , and press-fit into pin holes  38  in the outer portions  37   b  of an offset plates  37  and pin holes  42  in one end portion of each of the reinforcing connecting plates  41 . A bushing  35  is attached to the bushing holes  39  in the inner plate portions  37   c  of the offset plates  37 . The pin  40  inserted through the bushing  35  is press-fit to the pin holes  45  of the outer plates  33 , and the ends of the pin  40  are inserted, with play, into the small bushings  43  attached to the holes  44  of the reinforcing connecting plates  41 . Rollers  34  are provided on the bushings that extend across the chain.  
           [0008]    In the chain, the pin  36 , secured to the offset plates  37  and the reinforcing connecting plates  41 , is inserted through a bushing  35 . The pin  40 , secured to the outer plates  33 , is inserted through a bushing  35  and small bushings  43 . Accordingly, in the connecting portion, the outer plates  33  and the inner plates  32  can articulate with respect to the offset plate  37  and the reinforcing connecting plate  41 .  
           [0009]    When a large force is applied to the ends of the pin  40  as a result of the application of tension, the pin  40  is liable to be bent since the ends of the pin  40  are is fitted into the small bushings  43  with play. When ends of the pin  40  are bent, they may be pulled out of the small bushings  43  in the reinforcing connecting plates  41 , and the pins  40  may become disengaged from the reinforcing connecting plates  41 . When a pin  40  becomes disengaged from a reinforcing connecting plate in this manner, the tension in the chain is applied to the offset plates  37 . Because the middle portion  37   a  of the offset plate has reduced strength because of its bends, the chain may be broken.  
           [0010]    Another type of chain, known as a “high strength chain,” has longer inner and outer plates. The gaps between the ends of the adjacent inner plates, and the gaps between the ends of the adjacent outer plates, are smaller than the corresponding gaps in a conventional chain. However, when these gaps are decreased, there is insufficient space to accommodate the bent portion of an offset plate, and consequently an offset plate corresponding to plate  37  in FIG. 7 cannot be used.  
           [0011]    Accordingly, objects of the invention are to solve the above-mentioned problems encountered in prior art chains; to provide an endless chain having an odd number of links, in which even if large force is applied to the chain, the chain is not liable to be broken at the connecting portion; and to provide a connecting portion even in a chain having smaller gaps between the ends of adjacent inner plates and smaller gaps between the ends of adjacent outer plates.  
         SUMMARY OF THE INVENTION  
         [0012]    In accordance with this invention, a chain having an odd number of links comprises a chain body composed of alternating inner plate links and outer plate links. Each inner plate link comprises a pair of side-by-side, spaced, inner plates, and a pair of bushings fixed to both inner plates. Each outer plate link comprises a pair of side-by-side, spaced, outer plates and a pair of connecting pins secured to both outer plates. The inner and outer plate links re connected in a series arrangement to form the chain body by the insertion of connecting pins of the outer plate links through bushings of the inner plate links. The chain body has first and second ends and terminates in inner plate links at both ends.  
           [0013]    The chain also comprises a first connecting plate disposed on the outside of an inner plate at one end of the chain body, and a connecting link including a second connecting plate disposed on the outside of the first connecting plate and on the outside of an inner plate on the other end of said chain body.  
           [0014]    The connecting link is formed by securing ends of a pair of long connecting pins respectively into a pair of pin-receiving holes formed in the second connecting plate. One end of the first connecting plate is connected to an inner plate link on one end of the chain body by inserting a connecting pin secured to the first connecting plate through a bushing of the inner plate link. The other end of the first connecting plate is connected to one end of the connecting link by inserting one of long connecting pins through a long bushing fixed to a bushing hole in the first connecting plate and through a spacer provided adjacent an inside face of the first connecting plate. The other end of the second connecting plate is connected to an inner plate link at the other end of the chain body by inserting the other long connecting pin through a bushing of the inner plate link at said other end of said chain body and through a spacer interposed between that inner plate link and an inside face of the second connecting plate. The first connecting plate and the inner plate link at said other end of said chain body are pivotable respectively on the long connecting pins.  
           [0015]    The endless chain in accordance with the invention has an odd number of links, and the connecting link which joins the ends of the chain body is formed in such a manner that the ends of the long connecting pins are secured in a pair of pin holes in the second, or outer, connecting plate. Even if a very large amount of tension is applied to the chain, the long connecting pins will not be pulled out of the second connecting plate, and the chain is much less susceptible, than conventional chains having odd numbers of links, to breakage at the location at which the ends of the chain body are joined. Furthermore the first connecting plates connected to one end of the chain body, and the inner link at the other end of the chain body are pivotally connected by means of long connecting pins which are inserted into bushings. Accordingly, the contact areas are long, and wear of the long connecting pins is suppressed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a plan view, partly in section of a connecting portion of a chain in accordance with a first embodiment of the invention;  
         [0017]    [0017]FIG. 2 is the side elevational view of the chain shown in FIG. 1;  
         [0018]    [0018]FIG. 3 is a plan view, partly in section of a connecting portion of a chain in accordance with a second embodiment of the invention;  
         [0019]    [0019]FIG. 4 is a cross-sectional view of a portion of a chain in accordance with the invention, in which a first connecting plate and a spacer are integrally formed as a unit;  
         [0020]    [0020]FIG. 5 is a cross-sectional view of a portion of a chain in accordance with the invention, in which a second connecting plate and a spacer are integrally formed as a unit;  
         [0021]    [0021]FIG. 6 is a cross-sectional view of a portion of a chain in accordance with the invention, in which an inner plate and a spacer are integrally formed as a unit; and  
         [0022]    [0022]FIG. 7 is a plan view, partly in section, of a connecting portion of a conventional chain.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    In a first embodiment of the invention, shown in FIGS. 1 and 2, ends  2   a  and  2   b  of a chain body  2  are connected to each other to form an endless chain  1 . The chain body is composed of a plurality of inner links  3  and outer links  7  connected to one another by connecting pins  9 . The ends of the chain body are connected to each other by a connecting link  14 .  
         [0024]    Each inner link  3  is formed by press-fitting a pair of bushings  6  into bushing holes  4   a  in a pair of inner plates  4 . A roller  5  is fitted to each bushing  6  with play. Each outer link  7  is formed by press-fitting a pair of connecting pins  9  into pin holes in a pair of outer plates  8 . The chain body  2  is formed by connecting the inner and outer links to each other in alternation along a longitudinal direction of the chain by inserting connecting pins  9  of the outer links  7  through bushings  6  of the inner links  4 .  
         [0025]    To complete the endless chain  1 , the ends  2   a  and  2   b  of the chain body  2  are connected to each other by the connecting link  14 , which comprises a pair of first connecting plates  11  and a pair of second connecting plates  12 . The first connecting plates  11  are disposed outside the inner link  3  at one end of the chain body  2 , and the second connecting plates  12  are disposed outside the first connecting plates  11 . Thus, the connecting plates  12  are disposed on the outermost part of the chain. The chain  1  is effectively composed of an odd number of links by the addition of the connecting link  14 .  
         [0026]    A pair of long connecting pins  13  is press-fit into pin holes  12   a  of a pair of second connecting plates  12 . A pin hole  11   a  is provided in an end portion of each of the first connecting plates  11 , and a bushing hole lib is provided in the other end portion of each of the first connecting plates  11 . A pin  9 , is inserted though a bushing  6  of the inner link  3  at end  2   a  of the chain body  2 . The ends  9   a  of this connecting pin  9  are fitted to the pin holes  11   a  at the end portions of the first connecting plates  11 . A long bushing  16  is fitted to bushing holes  11   b  at the other end portion of the first connecting plate  11 . Disc-shaped spacers  15 , which are in contact with a roller  5  surrounding bushing  16 , are provided on the inside faces of the first connecting plates  11 . The long bushing  16  extends through these spacers  15 , and may be either secured to the spacers, or extend through the spacers with play.  
         [0027]    The long connecting pin  13  secured to the left end portions of the second connecting plate  12  as seen in FIG. 1 is inserted through the long bushing  16 , which is fixed to the bushing holes lib of the first connecting plate  11 . The long connecting pin  13  secured to the right end portions of the second connecting plates  12  is inserted through another long bushing  16  which protrudes through the inner plate  4  at the other end portion  2   b  of the chain body  2 . A second disc-shaped spacer  17  is provided adjacent the inside faces of the second connecting plates  12 , between the second connecting plates  12  and the inner plates  4  of the inner link  3  at end portion  2   b  of the chain body  2 . Spacer  17  can be either fitted to the long bushing  16  or rotatable thereon.  
         [0028]    Because the connecting portion is constructed as described above, the first connecting plates  11  and the inner link  3  at end portion  2   b  of the chain body  2  are pivotable relative to the long connecting pins  13 , and therefore the chain  1  is articulated at its connecting portion. When tension is applied to the chain, since the long connecting pins  13  are secured to the second connecting plates  12 , the long connecting pins  13  cannot be pulled out of the holes in plates  12  and breakage of the chain at the connecting portion is prevented.  
         [0029]    Because each of the long connecting pins  13  is inserted through along bushing  16 , the contact area of the pins  13  with the long bushings  16  is long, and wear is suppressed. Moreover, because the long connecting pins  13  are secured to the second connecting plate  12 , both the inner links  3 , and outer links  7 , of the chain body  2  can have the same strength, so that breakage of the chain at the connecting portion can be prevented.  
         [0030]    In the alternative embodiment shown in FIG. 3, chain components corresponding to those of FIG. 1 are designated by the same reference numerals. The chain  1 ′ in FIG. 3 is different from the chain  1  in FIG. 1 in that, instead of mounting the spacer  17  onto the long bushing  16 , a spacer  18  is either secured to a long connecting pin  13 , or fitted onto the long connecting pin with play.  
         [0031]    In FIG. 3, ends  2   a  and  2   b  of a chain body are connected to each other to form an endless chain. The chain  1 ′ is formed by connecting inner links  3  and outer links  7  to one another using connecting pins  9 . The ends of the chain are connected by a connecting link  14 , having first connecting plate  11  and a second connecting plate  12 .  
         [0032]    Each inner link  3  is formed by press-fitting a pair of bushings  6  into bushing holes  4   a  in a pair of inner plates  4 . A roller  5  is fitted to each bushing  6  with play. Each outer link  7  is formed by press-fitting a pair of connecting pins  9  into pin holes in a pair of outer plates  8 . The chain body  2  is formed by connecting the inner and outer links to each other in alternation along a longitudinal direction by inserting connecting pins  9  of the outer links  7  through bushings  6  of the inner links  4 . Rollers  5  fit onto the bushings  6  with play.  
         [0033]    To complete the endless chain  1 ′, the ends  2   a  and  2   b  of the chain body  2  are connected to each other by the connecting link  14 , which comprises a pair of first connecting plates  11  and a pair of second connecting plates  12 . The first connecting plates  11  are disposed outside the inner link  3  at one end of the chain body  2 , and the second connecting plates  12  are disposed outside the first connecting plates  11 . In the connecting link  14 , two long connecting pins  13  are press-fit into pin holes  12   a  of a pair of second connecting plates  12 .  
         [0034]    Pin holes  11   a , of an inner link  3  at one end of the chain body, are provided in end portions of connecting plates  11 , and bushing holes  11   b  are provided in the other end portions of plates  11 . Pin  9  is inserted through the bushing  6 , and ends  9   a  of pin  9  are secured to pin holes  11   a . Ends of a long bushing  16  are fixed in bushing holes  11   b  in plates  11 . Disc-shaped spacers  15  are provided on the inside faces of the connecting plates  11 , in contact with a roller  5 . The long bushing  16  extends through these spacers  15 , and may be either secured to the spacers, or extend through the spacers with play.  
         [0035]    The long connecting pin  13 , which is secured to the left end portions of the second connecting plates  12 , is inserted through the long bushing  16  which fixed to the bushing holes  11   b  of the first connecting plates  11 . The other long connecting pin  13 , which is secured to the right end portions of plates  12 , is inserted through the bushing  6  of the inner link  3  at end portion  2   b  of the chain body  2 . Disc-shaped spacers  18  are provided on the inside faces of the second connecting plate  12 , between the second connecting plate  12  and the inner plate  4  of the inner link  3  at end portion  2   b  of the chain body  2 . The spacer  18  may be either fixed to the long bushing  16  or rotatable thereon.  
         [0036]    When the connecting portion is constructed as described above, the first connecting plates  11 , and the inner link  3  at the other end portion  2   b  of the chain body  2 , are both pivotable on long connecting pins  13 , and the chain  1 ′ is articulated at the connecting portion. When tension is applied to the chain  1 ′, since the long connecting pins  13  are secured to the second connecting plates  12 , the long connecting pins  13  do not become disengaged from the plates  12 , and breakage of the chain  1 ′ at the connecting portion is prevented  
         [0037]    Since the long connecting pins  13  are inserted through bushings  6  and  16 , the contact areas between the pins  13  and the bushings are long, and wear is reduced. Furthermore, since the long connecting pins  13  are secured to the second connecting plate  12 , the inner links  3  and outer links  7 , which form the chain body  2 , can have the same strength, so that breakage of the chain at the connecting portion is prevented.  
         [0038]    In the first and second embodiments described above, the spacer  15 , provided on the inside faces of end portions of the first connecting plates  11 , and the spacers  17  and  18 , provided on the inside faces of end portions of the second connecting plates  12 , are provided as elements separate from the connecting plates. However, as an alternative, a spacer and a plate may be formed as a unit, so that a spacer may be provided as an integral part of a connecting plate  11 ,  12 , or  4 , as shown respectively in FIGS. 4, 5, and  6 .  
         [0039]    As shown in FIG. 4, a first connecting plate  11  may be integrally formed with a spacer  15  and fitted onto a long bushing  16  with play. As shown in FIG. 5, a second connecting plate  12  may be integrally formed with a spacer  18 , and a long connecting pin  13  may be secured to a pin hole  18   a , which extends through the part of the connecting plate  12  that includes the spacer  18 . As shown in FIG. 6, an inner plate  4  at an end portion of the chain body may be integrally formed with a spacer  17  and fitted to a long bushing  16  with play.  
         [0040]    These spacers may be disc-shaped, or can have other shapes such as an oval or rectangular shape. The length of the spacer is preferably substantially half the length of the plate of which it is an integral part. The thickness of the spacer is preferably substantially the same as the thickness of the other end of the plate.  
         [0041]    In the chain according to the invention, the first connecting plates, and the inner link at the other end of the chain body, are both pivotable with respect to the respective long connecting pins of the connecting link so that the chain can be articulated or bent in the connecting portions. Furthermore, when tension is applied to the chain, since the ends of the long connecting pin are secured to a pair of pin holes in the second connecting plates, the long connecting pins cannot be pulled out of the second connecting plates. Accordingly, breakage of the chain at the connecting portion is prevented. Since the long connecting pins are inserted in bushings, the contact areas of the long pin with the bushings are large, and consequently chain breakage due to wear is prevented.  
         [0042]    Because the connecting link formed is formed by securing long connecting pins to the second connecting plates, the inner and outer links, which form the chain body, can have the same strength, so that further assurance is provided against chain breakage at the connecting portion.  
         [0043]    Because the spacers provided inside the second connecting plates of the connecting link have no bents portions, unlike the offset plate in the prior art, the spacer can be provided in various shapes. Thus, it can be disc-shaped, oval, or rectangular, for example. Finally, the spacer can be applied to chains having small gaps between the ends of the adjacent inner plates and between ends of the adjacent outer plates.