Abstract:
A chain having a plurality of inside links and guide links. The plurality of inside links each have a pair of apertures and are interleaved and connected to form rows. The plurality of guide links each have a pair of apertures and are placed outside of alternate rows of interleaved inside links to form guide rows. Connecting pins are received in the apertures and extend across the rows of the chain securing the links together. Spacing elements are found on opposite side of the chain, specifically between the guide links and the adjacent outermost inside links. The spacing elements act to maintain a spaced relationship between each of the guide link sand adjacent outermost inside links. At least one of the spacing elements on one side of the chain is a spring link holding the inside links in compressive frictional contact therebetween.

Description:
REFERENCE TO RELATED APPLICATIONS 
   This is a continuation-in-part of application Ser. No. 10/132,485, filed Apr. 25, 2002 now U.S. Pat. No. 6,595,882, entitled “Power Transmission Chain Having Links With Lateral Spacing Elements”, which is a divisional patent application of application Ser. No. 09/506,349, filed Feb. 17, 2000, entitled “Power Transmission Chain Having Links With Lateral Spacing Elements,” now U.S. Pat. No. 6,406,394, which claims benefit from provisional application No. 60/131,413 filed on Apr. 28, 1999. The aforementioned application(s) are hereby incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to the field of power transmission chains. More particularly, the invention pertains to a power transmission chain containing spacing elements to increase fatigue strength and decrease incidence of chain strand resonance. 
   2. Description of Related Art 
   One aspect of the invention relates to a silent or rocker joint chain, which has links having inverted teeth for engagement with an associated sprocket. Generally, rocker joint chains are used with sprockets for power transmission in transmissions, transfer cases, engine timing systems, and the like. Rocker joint chains are well known in the art. Examples include U.S. Pat. Nos. 5,651,746; 5,345,753; and 5,372,554 which are incorporated herein by reference. 
   Rocker joint chains are formed by the assembly of rows of links in lateral and longitudinal directions. Each link typically has a pair of teeth and a pair of pin apertures. The links are interlaced and then connected to each other by connecting pins inserted in each pin aperture. Guide links are utilized as the outermost links of the chain to maintain the chain on the sprockets when the chain is wrapped around the sprockets during operation. Guide links may be installed in the center or at both outer edges of the row of link plates arranged in the lateral direction. The guide links are conventionally press fit over pins, which connect the interlaced inside or articulating links. Guide links typically do not include inverted teeth. 
   Conventionally, a rocker joint is used as the connecting pin. The rocker joint is comprised of a pair of long and short pins. A first short pin, referred to as the rocker, is paired with a second longer pin. The longer pin has both ends fixed to guide links at the outmost flanks of the chain. 
   Conventional rocker joint chains are limited in the transfer of load between the rocker and the inside links that are positioned at the outermost end of the rocker. The limitation is due to the fact that only partial contact is obtained between these same inside links and the end of the rocker. A separate limitation concerns the contact between the outermost inside links and the sprocket. Due to the required chamfer on sprocket teeth and the axial clearance between the sprocket teeth and chain guide links only partial contact is achieved between the same inside links and the sprocket. 
   Prior art rocker joint chains showing the disadvantages in conventional chain designs are shown in  FIGS. 1–3  and  14 . The chain is comprised of rows of links. Alternate rows of links, or guide rows, have guide links press fit on their ends. The remaining rows, or non-guide rows, have inside links as their outermost links. 
     FIG. 1  shows a prior art rocker joint chain in a side view. Rows of inner links  21  in a guide row  12  alternately interleave with rows of inner links  21  in a non-guide row  14  and held by rocker joints comprising pairs of pins  16  and rockers  18 . A guide link  20  is fixed to the each end of the guide row  12  of inner links  21  by pins  16  which extend outwardly from the rows of inside links. 
   In the prior art rocker joint chain  10 , shown in  FIG. 2 , there is a clearance  30  between the end of the rocker  18  and the guide link  20 . This clearance  30  exists because of necessary manufacturing tolerances of the individual rockers  18  so that they are spaced from the guide links  20  after the assembly process. There also exists an end radius  19  on the rocker  18 , which is necessary to prevent excessive local stresses in the pin  16  and rocker  18 , and also for ease of assembly of the chain  10 . The clearance between the rocker  18  and the guide link  20  and the shortening of the rocker as a result of the end radius of the rocker, result in only partial bearing contact between the outermost inside links  22 ,  23  of the non-guide row, and the rocker. The partial bearing contact limits the load carrying capability of the chain because all of the links are not carrying their full share of the load. 
     FIG. 3  shows an exaggerated cross section through the chain of the prior art and sprocket  40 . The chain  10  is shown slightly out of position, i.e., raised vertically. The limitation in this design is that the contact area between the outermost inside links  22 ,  23  and sprocket tooth  25  is limited due to the chamfer  26  on the sprocket teeth and the necessary axial clearance between the chain  10  and sprocket  40 . Thus, the partial engagement or partial contact occurs between the outermost inside links  22 ,  23  of the non-guide row and the sprocket. 
     FIG. 14  shows a conventional rocker joint chain with a centered spring link  32 . Spring links are used in chains conventionally, to help control chain strand vibration by increasing the internal friction in the chain. Compression of the centered spring link  32 , in the direction shown by the arrow, forces the links in the rows to press against each other causing friction. The compression of the inside links  21  in the non-guide row  14  against the outside guide links  20  could cause a gap great enough that the rocker pin  18  may become disengaged from the outside guide links  20 , forcing the non-guide row  14  of inside links  21  apart, resulting in a loss of chain strength. 
   The present invention also has application to silent chains with round connecting pins. An example of a round pin silent chain is shown in U.S. Pat. No. 4,758,209, which is incorporated herein by reference. While there is no rocker in a round pin chain, the spacing elements, especially when they are spring links, help center the inside links between the guide links. This helps provide full engagement of the inside links with the sprocket teeth, helping to distribute the load between the chain and the sprocket more evenly than in a chain without spacing elements. This affect is also beneficial in a rocker joint chain. 
   The present invention also has application to chain belts, as shown in U.S. Pat. Nos. 4,580,999 and 5,439,423 which are incorporated herein by reference. 
   SUMMARY OF THE INVENTION 
   A chain having a plurality of inside links and guide links. The plurality of inside links each have a pair of apertures and are interleaved and connected to form rows. The plurality of guide links each have a pair of apertures and are placed outside of alternate rows of interleaved inside links to form guide rows. Connecting pins are received in the apertures and extend across the rows of the chain securing the links together. Spacing elements are found on opposite side of the chain, specifically between the guide links and the adjacent outermost inside links. The spacing elements act to maintain a spaced relationship between each of the guide link sand adjacent outermost inside links. At least one of the spacing elements on one side of the chain is a spring link holding the inside links in compressive frictional contact therebetween. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a longitudinal side view of a portion of a prior art rocker joint chain. 
       FIG. 2  is a sectional view of a portion of a prior art rocker joint chain. 
       FIG. 3  is a sectional end view illustrating the spacing between the sprocket and guide links in a prior art rocker joint chain. 
       FIG. 4  is a sectional view of the power transmission chain of the present invention showing the projections from the guide links. 
       FIG. 5  is a sectional view of the power transmission of the present invention showing an alternate location of the projections. 
       FIG. 6A  is a perspective view of the inside face of the guide link with two projections. 
       FIG. 6B  is a perspective view of the outside face of the guide link with two projections. 
       FIG. 6C  is a perspective view of the inside face of the guide link with four projections. 
       FIG. 6D  is a perspective view of the outside face of the guide link with four projections. 
       FIG. 6E  is a longitudinal side view of a portion of a power transmission chain of the present invention showing the guide link side opposite the projections. 
       FIG. 7  is a sectional end view showing the projections. 
       FIG. 8  is a sectional view showing the location of the washers. 
       FIG. 9  is a sectional view showing the curved end elements of the guide links. 
       FIG. 10  is a partial sectional view showing an embodiment of the curved mid-elements of the guide links. 
       FIG. 11  is another embodiment of the curved mid-elements. 
       FIG. 12  is a side view of a chain belt. 
       FIG. 13  is a sectional view of the chain belt of  FIG. 12  with spacing elements.  FIG. 1  shows 
       FIG. 14  shows top down view of a prior art rocker joint chain with a centered spring link. 
       FIG. 15A  shows a top down view of another embodiment in which a pair of spring links in one configuration are used as spacing elements. 
       FIG. 15B  shows a top down view of another embodiment in which a pair of spring links in a different configuration are used as spacing elements than that shown in  FIG. 15A . 
       FIG. 16  shows a top down view of an alternative embodiment of the present invention. 
       FIGS. 17A and 17B  show a side view and top view from the chain point of view of an example of a spring link used in the present invention. 
       FIGS. 18A and 18B  show additional embodiments. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention addresses the above-described problems by providing in a power transmission chain, in general terms, a spacing element to ensure that there is full engagement of the rocker and the non-guide row of links to increase the fatigue strength of the chain, while keeping the friction present in the chain at a point such that chain strand resonance is prevented. The present invention also allows increased sprocket width providing better contact between the chain and sprocket. The present invention is explained below with reference to the embodiments illustrated by the attached figures. 
     FIG. 4  shows a sectional view of a preferred embodiment of a rocker joint chain  111  of the present invention. As in the prior art, the chain is constructed from the assembly of interleaved rows of links. Inside links  121  are flanked by guide links  120  and connected by connecting pins, each comprising a pin  116  and a rocker  118 . The guide links  120  and inside links  121  are shown more clearly in  FIG. 6E . The inside links shown in  FIG. 6E  are shown as each having a pair of depending teeth adapted to contact the teeth of an associated sprocket (not shown). It should be understood that other configurations of inner links are contemplated, such as links with a single depending tooth as disclosed in U.S. Pat. No. 5,435,789, incorporated herein by reference. 
   In the chain of the present invention, the guide links maintain the lateral alignment of the chain on the sprockets. The guide links  120  are located along the outside of the chain, i.e., flanking the outermost inside links  122 ,  123  and do not have teeth for engagement with the sprocket teeth. The guide link  120  has projections  160  formed on an inner face. The projections  160  bear upon outermost inside links  122 ,  123  and act to maintain a space between the main body of the guide links  120  and the inside links  122 ,  121 ,  123 . Complete bearing contact between the rocker  118  and the outermost inside links  122 ,  123  at surface  134  is provided by virtue of the slight increase in rocker length allowed by the increased space between the guide links  120  and the outermost inside links  122 ,  123 . 
   An alternate embodiment of the present invention shown in  FIG. 4  is illustrated in  FIG. 5 . Projections  162  are formed on the outside face of the outermost inside links  122 ,  123 . Each projection  162  serves the same function as projection  160  in  FIG. 4 , i.e., which is to space apart the inside links  121 ,  122 ,  123  from the guide links  120  to provide increased axial clearance. While operating like the embodiment shown in  FIG. 4 , the present embodiment requires the manufacture of three different link types as opposed to two. 
     FIGS. 6A and 6B  show an inside and outside view respectively of one embodiment of a guide link of the present invention. Guide link  120  has a pair of projections  160  on an inside surface  180  of the link plate. The projections  160  are located below the guide link plate apertures  106 . The corresponding recesses or locations  168  are shown on the outside surface  182  of the guide link  120 . 
     FIGS. 6C and 6D  show an inside and outside view respectively of another embodiment of a guide link of the present invention. Guide link  220  has two pair of projections  260   a,    260   b  on an inside surface  280  of the link plate. The projections  260   a  are located below the guide link plate apertures  206 , and the projections  260   b  are located above the guide link plate apertures  206 . Note that the top of the guide link has been widened above each aperture to allow space for both the aperture and the projection. The corresponding recesses or locations  268   a,    268   b  are shown on the outside surface  282  of the guide link  220 . 
     FIG. 6E  shows one embodiment of the location  168  of the projections  160  formed into the guide links  120  shown in  FIG. 4  and  FIGS. 6A and 6B . However, the projections  160  can be located in any portion of the guide link which allows contact with the outermost inside links  122 ,  123  and provides the desired axial spacing. The projections  160  can be formed by various methods including pressing, stamping, molding, machining or the like. Location  168  may also correspond to a recess or dimple formed on the outer face of the guide link  120  when creating the projections on the inner face of the guide link  120  by a stamping process. 
     FIG. 7  shows a preferred embodiment of the chain and sprocket in cross section. Projections  160  are shown on guide links  120 , which bear upon outermost inside links  122 ,  123 . With the additional axial space created by the projections  160 , the sprocket  140  width can be increased to assure full contact with all the inside links  121  including the outermost inside links  122 ,  123 . The additional contact will reduce wear and contact stress between the chain and sprockets, which may in turn allow substitution of lower cost materials or processes for the sprocket, reducing overall system cost. 
     FIG. 8  illustrates another embodiment of the present invention. A washer  164  encircles the rocker joint between the guide links  120  and the inside links  121 . The rocker  118  and the outermost inside links  122 ,  123  are in full contact at surface  134  due to the increased length of the rocker  118  allowed by increased clearance in the axial direction. The washer  164  need not be integral with the guide links or the inside links. 
   In  FIG. 9  guide links  120  have curved end elements or portions  166  located at each of the distal ends of the guide link  120 . Each curved end portion  166  extends inwardly toward the adjacent outermost inside link. The desired axial spacing is maintained by the curved end portions  166  bearing upon the outer face of the outermost inside links  122 ,  123 . 
     FIGS. 10 and 11  illustrate in a simplified partial view alternate embodiments of the curved end portions  166  of  FIG. 9 . Curved mid-portions  170 ,  172  are portions of the guide link  120  which deviate from the typical flat plate-like guide link shape of the prior art. The curved mid-portions  170 ,  172  are located in the midsection of the guide link  120  and serve to maintain a space between the guide link  120  and an adjacent outmost inside link  122 . An identical curved guide link  120  with a curved mid-portion  170  or  172  would be placed on the opposite side of the chain. 
     FIGS. 12 and 13  illustrate a power transmission chain belt  210 . Generally, as shown in  FIG. 12 , the chain belt includes links arranged in sets A and B which are interleaved or “laced” with one another. A “set” of links are those links which are grouped transversely together; at times a set of links is referred to as a “rank.” Each link is provided with a pair of apertures  215 , each aperture being adjacent to an end of the link plate, with the apertures in a set being aligned with one another. When interlaced with other sets of links, the apertures  215  at one end are transversely aligned with those in the interleaved set, so that the connecting pin interconnects the interlaced links. The connecting pin typically includes a rocker  218  and a pin member  216 . The pin member  216  extends through and is press fit to the apertures of the outermost link plates  220  which are located on the flanks of alternate sets of links. The rocker  218  extends through the apertures of the remaining links, at times referred to as the inside links  221 , stopping short of the outermost or guide links  220 . Struts  217  for engaging a pulley transmission (not shown) are provided to the chain either positioned in a passageway defined by toes which depending from each link or wrapped around the chain. Load blocks (not shown) may be wrapped about the chain to engage a pulley transmission. 
   As shown in  FIG. 13 , spacing elements or members  260  are applied to inside faces of the guide links  220 . The benefit of spacing elements as applied to a chain type belt is directed to the increase in contact area between the rocker pin and the outermost inside link aperture. 
     FIG. 15A  shows another alternative embodiment of the present invention in which a pair of separated spring links  332  are used as spacing elements. A front and side view of an example of a spring link  332  that may be used in the embodiment are shown in  FIGS. 17A and 17B . As in the other embodiments of the present invention, the chain is constructed from an assembly of interleaved rows of links. Inside links  121  are flanked by guide links  120  and connected by connecting pins, each comprising a pin  116  and a rocker  118 . The guide links  120  are located along the outside of the chain, i.e., flanking the outermost inside links  122 ,  123  and do not have teeth for engagement with the sprocket teeth. A pair of spring links  332  are used as spacing elements between the non-guide row  114  of the outermost inside links  122 ,  123  and the row of outside guide links  120 . The springs links  332  are arranged such that the ends of the spring links are in contact with the inside links. As in the other embodiments of the present invention, the spacing element provides an increased amount of space, allowing for a longer rocker pin, which will not cause a gap event as in prior art  FIG. 14 . In this case the spacing element is a spring link. Unlike in the prior art, the inside links  121  in the non-guide rows  114  are not compressed in such a fashion as to allow the rocker pin  118  to become disengaged from the inside links  121 . Thus, the spring links  332  provide a spacing element between the outside guide links  120  and the inner links  121  in non-guide rows  114  and also increases the internal friction in the chain helping to control chain strand vibration.  FIG. 15B  shows an alternative configuration of the above embodiment. The spring links  332  in this configuration perform the same function as in  FIG. 15A , but are rotated 180°, such that the ends of the spring links are in contact with the guide links. 
   Additional embodiments (similar to that of  FIG. 15A ) include the use of one spring link and one chain washer, or one spring link and one curved mid-portion of a guide link, as shown in  FIGS. 18A and 18B . 
     FIG. 16  shows another embodiment of the present invention. In this embodiment, one spring link  400  is placed on one side of the chain between the non-guide row  114  of inside links  121  and the outside guide links  120 . On the other side of the chain is an outside guide link  120  that has a pair of projections  160  on an inside surface  180  of the link plate  120 . The projections  160  are located below the guide link plate apertures  106 . The corresponding recesses or locations  168  are shown on the outside surface  182  of the guide link  120 . However, the projections  160  may be located in any portion of the guide link which allows contact with the outermost inside links  122 ,  123 , and provides the desired axial spacing. The projections  160  may be formed by various methods including pressing, stamping, molding, machining or the like. The combination of the spring link  400  and the projections  160  ensures that the rocker pin  118  protrudes completely through the outermost non-guide row  114  links  122 ,  123  lending full support to the chain. 
   The spacing thus provided between the guide link and the inside links allows the rocker to contact against the entire bearing surface of the aperture of the outermost inside link. In addition, the spacing provides complete engagement of all the inside links with the entire width of the sprocket. Minimizing the clearance between the rocker and guide link serves to lessen the amount of rocker movement and helps to maintain the stated advantages. 
   Those skilled in the art to which the invention pertains may make modifications and other embodiments employing the principles of this invention without departing from its spirit or essential characteristics particularly upon considering the foregoing teachings. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. Consequently, while the invention has been described with reference to particular embodiments, modifications of structure, sequence, materials and the like would be apparent to those skilled in the art, yet still fall within the scope of the invention.