Abstract:
The invention is a chain unit comprising first and second link units, a unitary outer plate, and first and second pins. Each link unit comprises two inner plates with two rollers positioned therebetween. The outer plate straddles and is secured to the link units. Outer plate comprises two walls and a bridge positioned therebetween that spans the tooth engaging space between link units. The unitary construction of the outer plate provides a structural integrity that prevents the plates from separating when the chain is exposed to force. A plurality of chain units can be linked together to form a chain.

Description:
FIELD OF INVENTION 
       [0001]    The invention relates to chain units and particularly to chain units having a unitary outer plate. 
       BACKGROUND OF INVENTION 
       [0002]    Standard bicycle chains are primarily designed to transfer and handle drive loads to the back wheel. While the traditional design works well to transfer loads, one shortcoming of the chains known in the art is that the chains become weak when they are exposed to excessive forces. However, modern bicycles are often used in environments where the chain comes into contact with objects in the environment at various angles and speeds, thereby subjecting the chain to excessive forces. If an object contacts the chain at an angle that is not in line with the drive direction, the outer plates of the chain can bend and pull from the pin. This causes the chain to break from the impact or to weaken to a point that it fails when a drive load is placed upon it. Such damage endangers the rider. Bicycle chains known in the art have tried to address the problem in different ways, such as by using larger and thicker plates and/or riveted pins. While using a larger chain and plates may strengthen the chain so that it can withstand impacts, these larger chains can weigh up to a pound or more. The added weight is inefficient because it can impact the rider&#39;s performance. Further, often times these larger chains do not fit well on sprockets. In some instances, larger chains do not fit on the sprocket at all. In fact, in recent years, sprockets have become smaller (i.e., they have fewer teeth), and as a result, large chains cannot make the tight bends. Further, even when the larger chains do fit on the sprocket, the larger chains tend to wear the sprocket teeth down faster, thereby reducing the lifespan of the sprocket teeth. Thus, there is a need for a bicycle chain that can both withstand impacts and function in an effective and efficient manner. 
       SUMMARY OF INVENTION 
       [0003]    The present invention meets this need by providing a chain unit that is strong enough to withstand impacts with objects that are encountered in the environment and that is sized to work efficiently in the chain unit. 
         [0004]    It is therefore an object of the claimed invention to provide a chain unit that is strong enough to withstand impacts from objects encountered during use. 
         [0005]    It is another object of the claimed invention to provide a chain unit that has an outer plate that is strong enough to resist bending or breaking when it is impacted by foreign objects. 
         [0006]    It is still a further object of the claimed invention to provide a chain unit that has a unitary outer plate. 
         [0007]    It is still a further object of the claimed invention to provide an outer plate that can be retrofitted to connect to the inner plates of a conventional chain. 
         [0008]    It is another object of the claimed invention to provide a chain made of a plurality of chain units having unitary outer plates. 
         [0009]    It is yet another object of the claimed invention to provide an outer plate that is substituted for the conventional outer plate on a conventional chain. 
         [0010]    In an embodiment, the claimed invention is a chain unit comprising first and second link units, a unitary outer plate, and first and second pins. Each link unit comprises two inner plates positioned in a first plane and being substantially parallel to each other. The inner plates are separated by a first distance. Each inner plate has first and second holes that substantially align with first and second holes in the other inner plate. There are two rollers positioned in the space between the inner plates of each link unit. Rollers are separated from each other by a first tooth engaging space. One roller has a hole that substantially aligns with first holes in the inner plates and the other roller has a hole that substantially aligns with second holes in the inner plates. The unitary outer plate straddles the second end region of the first link unit and the first end region of the second link unit. The outer plate comprises two walls and a bridge. The walls are positioned in the first plane, are separated by a second distance, and are substantially parallel to each other and to the inner plates. A second surface of one wall opposes the first surface of one inner plate and the second surface of the other wall opposes the first surface of the other inner plate. First holes in each wall substantially align with second holes of inner plates of first link unit and second holes in each wall substantially align with first holes of inner plates of second link unit. The bridge of the outer plate is positioned in a second plane and between the two walls. Second plane is substantially perpendicular to the first plane. The bridge substantially spans second tooth engaging space. Outer plate is secured to first link unit by a first pin and to second link unit by a second pin. The unitary outer plate construction provides a structural integrity that prevents the outer plate from pulling apart from the inner plates when a force is applied to the chain unit in a direction that is not parallel to the drive direction. 
         [0011]    Another embodiment is for a unitary outer plate for use with a chain. 
         [0012]    Another embodiment is for a chain comprised of a plurality of chain units that may optionally be combined with a bicycle. 
         [0013]    Those and other details, objects, and advantages of the present invention will become better understood or apparent from the following description and drawings showing embodiments thereof. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The accompanying drawings illustrate examples of embodiments of the invention. In such drawings: 
           [0015]      FIG. 1A  shows a top view of an example of an embodiment of the claimed unitary outer plate,  FIG. 1B  shows a side view of an example of an embodiment of the claimed unitary outer plate, and  FIG. 1C  shows an end view of an example of an embodiment of the claimed unitary outer plate. 
           [0016]      FIG. 2  shows an isometric view of an example of an embodiment of the claimed unitary outer plate. 
           [0017]      FIG. 3  shows an isometric view of an example of an embodiment of the claimed chain unit. 
           [0018]      FIG. 4  shows a side view of an example of an embodiment of the claimed chain in combination with a sprocket. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0019]      FIG. 3  shows an isometric view of an example of an embodiment of the claimed chain unit  40 . In an embodiment, each chain unit  40  comprises two link units  10 ,  10 ′, a unitary outer plate  30 , and first  6  and second  7  pins. Each link unit  10 ,  10 ′ comprises two inner plates  11 ,  11  and first  1  and second  2  rollers. Inner plates  11 ,  11  are made of steel or titanium. Inner plates  11 ,  11  are positioned substantially parallel to each other in first plane and are separated by a distance  51  therebetween. In an example, distance  51  is about 0.105-0.145 inches and is preferably about 0.125 inch (⅛ inch). In another example, distance  51  is about 0.074 to about 0.114 inch, and is preferably about 0.09375 inch ( 3/32 inch). Inner plates  11 ,  11  have first  16  and second  17  surfaces and first  18  and second  19  holes, respectively. Second surfaces  17  of the two inner  11 ,  11  plates of one link unit are opposed to each other. Each inner plate  11 ,  11  has first  12  and second  14  end regions and a solid middle region  13 . In an example, end regions  12 ,  14  have substantially equal heights and are larger than the height of middle region  13 . In other examples, the shape and size of inner plates,  11 ,  11  is varied. First hole  18  is located in first  12  end region of each inner plate  11  and second hole  19  is located in second end region  14 . Holes  18 ,  19  are sized such that pins  6 ,  7 , described in more detail below, fit therein and extend there through. In an example, a bushing (not shown) is positioned in each of first  18  and second  19  holes. In an example, pins  6 ,  7  have diameters of about 2.5 to about 4.4 mm, and preferably about 3.5 mm. In other examples, an inner edge of each hole  18 ,  19  has an outwardly extending lip  18   a,    19   a  on which pin  6 ,  7  rests. To allow for easy rotation, holes  18 ,  19  have diameters of about 2.6 to about 4.5 mm, and preferably about 3.55 to about 3.66 mm. 
         [0020]    Each link unit  10 ,  10 ′ further comprises first  1  and second  2  rollers or axles positioned between inner plates  11 ,  11 . In examples, rollers  1 ,  2  have a diameter of about 5.6 to about 9.4 mm, and preferably about 7.55 mm. First roller  1  has a hole (not shown) that substantially aligns with first holes  18 ,  18  in inner plates  11 ,  11  and second roller  2  has a hole (not shown) that substantially aligns with second holes  19 ,  19  in inner plates  11 ,  11  of each link unit. There is a first tooth engaging space  53  between rollers  1 ,  2 . Preferably, there is a distance of about 0.4 inch to about 0.6 inch from center of roller  1  to center of roller  2 . Rollers  1 ,  2  each have a contacting surface  1   a,    2   a  that contacts teeth  41  of sprocket  42  (described below) and that rotates in drive direction D. 
         [0021]    The claimed chain unit  40  further comprises a unitary outer plate  30  shown in the figures, and particularly in  FIGS. 1 and 2 . In an example, unitary outer plate  30  is an inverted U-shaped member. In examples, outer plate  30  is made of steel or titanium. In an example, unitary outer plate  30  is made of the same material from which inner plates  11 ,  11  are made. In another example, outer plate  30  is made of a different material from which inner plates  11 ,  11  are made. Unitary outer plate  30  comprises two walls  31  and a bridge  39  positioned therebetween. Walls  31 ,  31  each have first  36  and second  37  surfaces. 
         [0022]    Walls  31 ,  31  are positioned substantially parallel to inner plates  11 ,  11  in first plane. Walls  11 ,  11  define a second space  52  therebetween. Second space  52  is slightly larger than first space  51 . Second space  52  is preferably wide enough for inner plates  11 ,  11 , bushings, and rollers  1 ,  2  to fit between walls  31 ,  31 . Inner plates  11 ,  11  slide and rotate freely on pins  6 ,  7  such that their position between walls  31 ,  31  of outer plate  30  is not fixed. In an example, distance of second space  52  is such that second surface  37  of wall  31  does not touch first surface  16  of inner plate  11 . In another example, second surface  37  of at least one wall  31  does contact first surface  16  of at least one inner plate  11 . 
         [0023]    Walls  31 ,  31  have a size and shape that is substantially complementary to a size and shape of inner plates  11 ,  11 . As described above in regards to inner plates  11 ,  11 , each wall  31 ,  31  has first  32  and second  34  end regions and a middle region  33 . 
         [0024]    Each outer plate  30  of a chain unit straddles two link units  10 ,  10 ′. As shown in  FIG. 3 , first end region  32  straddles second end region  14  of first link unit  10  and second end region  34  straddles first end regions  12 ,  12  of the second link unit  10 ′. Second surface  37  of one wall  31  opposes first surface  16  of one inner plate  11  and second surface  37  of the other wall  31  opposes first surface  16  of other inner plate  11 . 
         [0025]    Each wall  31  has first  18  and second  19  holes that are preferably located near first  32  and second  34  end regions of each wall  31 ,  31 , respectively. In an example, pins  6 ,  7  fit snugly in holes  18 ,  19 . In an example, holes  18 ,  19  have diameters of about 2.45 to about 4.45 depending on pin  6 ,  7  diameter. First hole  18 ,  18  substantially align with second hole  19 ,  19  in first inner plates  11 ,  11  of first link unit  10  and second holes  19 ,  19  substantially align with first holes  18 ,  18  in first inner plates  11 ,  11  of second link unit  10 ′. 
         [0026]    Unitary outer plate  30  further comprises a bridge  39 , as shown particularly in  FIGS. 1-3 . Bridge  39  is positioned between walls  31 ,  31  in a second plane that is substantially perpendicular to first plane. Bridge  39  substantially spans second tooth engaging space  54 . Preferably, walls  31 ,  31  and bridge  39  intersect at an angle α that is about 67° to about 113°, and preferably about 90°. Walls  31 ,  31  have a height H that is high enough to allow for clearance of inner plates  11 ,  11  such that walls  31 ,  31  substantially cover inner plates  11 ,  11 . Bridge  39  may be a solid piece of material (not shown) or may optionally have at least one hole  39   a  to reduce weight. Further, end pieces of bridge may be substantially straight (not shown) or may optionally be trimmed to reduce weight of bridge  39 . Thus the structure defined by the bridge and walls comprises an inverted U-shaped base member. 
         [0027]    Outer plate  30  is secured to inner plates  11 ,  11  by first  6  and second  7  pins that extend through holes  18 ,  19  at a substantially constant pitch of about 0.4 to about 0.6 mm. In an example, first pin  6  extends through first hole  28  in one of walls  31 , second hole  19  in one of inner plates  11  of first link unit  10 , hole in second roller  2  of first link unit  10 , second hole  19  in the other inner plate  11 , and first hole  28  in the other wall  31 . Second pin  7  extends through second hole  29  in one of walls  31 , first hole  18  in one inner plates  11  of second link unit  10 ′, hole in first roller  1  of second link unit  10 ′, first hole  18  in the other inner plate  11 , and second hole  29  in the other wall  31 . Optionally, there is a bushing (not shown) positioned in each of first  18  and second  19  holes in inner plates  11 ,  11 . 
         [0028]    In another embodiment, the claimed invention is a unitary outer plate  30  for use with a chain  100 . As described above, the unitary outer plate  30  comprises first and second two walls  31 ,  31  and a bridge  39  and is capable of straddling and being secured to two link units  10 ,  10 ′ of a chain. In an example, each inner plate  11 ,  11  of the link unit  10  to which outer plate is being attached or secured has two holes  18 ,  19  that substantially align with holes  28 ,  29 , respectively, in walls  31 ,  31  of outer plate  30 , as described above. First end region  32  of outer plate  30  is secured to second end region  14  of first link unit and second end  34  region of outer plate  30  is secured to first end region  12  of second link unit  10 ′. In an example, outer plate  30  is secured to link units  10 ,  10 ′ by pins  6 ,  7  as described above. 
         [0029]    In an example, unitary outer plate  30  can be connected to inner plates  11 ,  11  of a conventional chain to replace conventional two-piece outer plates (not shown). 
         [0030]    In another embodiment, the claimed invention is a chain  100  comprised of a plurality of chain units  40  described above. Each chain unit  40  comprises two link units, another plate, and two pins as described above. Chain  100  is assembled by linking together a plurality of chain units as described above. As shown in  FIG. 4 , first end region  12  of each link unit  10 ,  10 ′ will have secured thereto a second end region  34  of an outer plate  30  and second end region  14  of each link unit  10 ,  10 ′ will have secured thereto a first end region  32  of an outer plate  30  to form a continuous chain. 
         [0031]    In an example, the chain  100  comprising a plurality of chain units  40  is combined with a bicycle (not shown). Drive sprocket  42  is rotated by the rider. As sprocket  42  is rotated, chain  100  is driven around sprocket  42 , causing secondary sprocket (not shown) affixed to rear wheel (not shown) to also rotate. As chain  100  rotates contacting surfaces  1   a,    2   a  of rollers  1 ,  2 , respectively, come into contact with and are engaged by sprocket teeth  41  to rotate roller  1 ,  2  about pin  6 ,  7 . The forces of the sprocket teeth  41  on the rollers  1 ,  2  are transferred to pins  6 ,  7  and then to inner  11 ,  11  and outer  30  plates. This is repeated through each chain unit  40 . 
         [0032]    While the foregoing has been set forth in considerable detail, it is to be understood that the drawings and detailed embodiments are presented for elucidation and not limitation. Design variations, especially in matters of shape, size, and arrangements of parts, may be made but are within the principles of the invention. Those skilled in the art will realize that such changes or modifications of the invention or combinations of elements, variations, equivalents, or improvements therein are still within the scope of the invention as defined in the appended claims.