Abstract:
An object of the present invention is to provide a chain reducing friction caused by sliding between the pin and the inner plate, whereby durability is improved, a frictional loss is reduced, and the reduction in size and cost can be implemented. In a silent chain, a guide row and a non-guide row, which are adjacent to each other in a longitudinal direction, are connected together in a bendable manner using a single pin movably inserted into a second pinhole of an inner plate. A hole peripheral wall surface forming the second pin hole has a plate rolling surface, and an outer peripheral surface of the pin has a pin rolling surface. During chain bending, the plate rolling surface rolls on the pin rolling surface.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a chain including a first link and a second link located adjacent to each other in a longitudinal direction and coupled together via a pin in a bendable manner, and in particular, to the shape of the pin and the shape of a pin hole into which the pin is inserted. 
         [0003]    The chain is, for example, a silent chain, and is used as a transmission chain in an automotive power unit. 
         [0004]    2. Description of the Related Art 
         [0005]    In a conventional chain of this kind, for example, a silent chain, a pin held in a pair of guide plates of the first link is inserted into a pin hole in a plurality of inner plates of the second link to connect the second link to the first link in a bendable manner (for example, Japanese Patent Application Laid-open No. H11-201238 (Paragraphs 0014 to 0017 and  FIG. 1  and  FIG. 2 ) and Japanese Patent Application Laid-open No. H8-68445 (Paragraphs 0010 and 0011 and  FIG. 1  to  FIG. 4 ). 
         [0006]    Ina chain in which, during chain bending when the second link bends relative to the first link, an outer peripheral surface of the pin held in the guide plates and a hole peripheral wall surface of the pin hole in the inner plates slide on the entire contact areas of the outer peripheral surface and the hole outer peripheral surface (for example, see Japanese Patent Application Laid-open No. H11-201238 (Paragraphs 0014 to 0017 and  FIG. 1  and  FIG. 2 ). In this case, the sliding makes the outer peripheral surface of the pin and the hole peripheral surface of the inner plate likely to wear progressively. Thus, disadvantageously, the chain becomes less durable, and power for driving the chain is subjected to a heavy frictional loss attributed to the chain. 
         [0007]    In another chain, in addition to the pin held in the guide plates, another pin (see, for example, Japanese Patent Application Laid-open No. F18-68445 (Paragraphs 0010 and 0011 and  FIG. 1  to  FIG. 4 ); the pin corresponds to a bush in the roller chain) is inserted into the pin hole in the inner plates. In this case, the pin hole is larger, and thus, the inner plates have an increased size to ensure the rigidity of the plates. This leads to an increased chain pitch, making miniaturization of the chain difficult. Moreover, a plurality of pins is needed. This results in an increase in the number of pins and the number of assembly steps and the need to machine the plurality of pins in addition to the pin hole. Thus, chain costs disadvantageously increase. 
         [0008]    The present invention solves these problems, and an object of the present invention is to provide a chain in which a hole peripheral wall surface of a pin hole in an inner plate into which a pin is inserted has a plate rolling surface that can roll on a pin rolling surface during chain bending, thus reducing friction caused by sliding between the pin and the inner plate, whereby durability is improved, a frictional loss is reduced, and the reduction in size and cost can be implemented. 
         [0009]    Another object of the present invention is to provide a chain having improved applicability to rotary wheels with different winding diameters. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention solves the above-described problems by providing a chain including: a plurality of first links; a plurality of second links; and a plurality of pins, the first link including a pair of holding plates, the second link including one or more inner plates disposed between the pair of holding plates in a width direction, the first link and the second link adjacent to each other in a longitudinal direction being coupled together in a bendable manner via the single pin movably inserted into a pin hole in the inner plate and held in a state where rotational movement of the pin is regulated by the pair of holding plates, the chain being wound around one or more rotary wheels, wherein a hole peripheral wall surface of the inner plate forming the pin hole has a plate rolling surface, an outer peripheral surface of the pin has a pin rolling surface, and the plate rolling surface rolls on the pin rolling surface during chain bending in which the second link bends relative to the first link. 
         [0011]    According to the chain of the present invention set forth in claim  1 , the hole peripheral wall surface of the inner plate forming the pin hole has the plate rolling surface, the outer peripheral surface of the pin has the pin rolling surface, and the plate rolling surface rolls on the pin rolling surface during chain bending when the second link bends relative to the first link. Thus, during chain bending, the plate rolling surface rolls on the pin rolling surface, and thus, this embodiment reduces possible friction between the outer peripheral surface and the hole peripheral wall surface compared to a case where the entire contact areas of the outer peripheral surface and the hole peripheral wall surface are slidable. This enables a reduction in wear of the outer peripheral surface and the hole peripheral wall surface, allowing the durability of the chain to be improved. Furthermore, a frictional loss attributed to the chain can be reduced. 
         [0012]    Furthermore, since the only one pin is inserted into the pin hole, the size of the pin hole can be reduced. This enables a reduction in chain pitch to allow the chain to be miniaturized. The number of pins and the number of assembly steps are reduced, thus enabling a reduction in chain costs. 
         [0013]    Moreover, the rolling surface (hereinafter referred to as the “opposite rolling surface”) that rolls on the pin rolling surface is a plate rolling surface formed on the inner plate, which is a member larger than the pin. Thus, compared to a case where the opposite rolling surface is formed on the pin, this embodiment enables an increase in the degree of freedom for the design of the shape of the opposite rolling surface. Moreover, the opposite rolling surface is formed by machining the pin hole. This enables a reduction in chain costs. 
         [0014]    According to the chain of the present invention set forth in claim  2 , the plate rolling surface and the pin rolling surface are protruding curved surfaces. Thus, the rolling surfaces, compared to a recessed curved surface, exhibit an increased ratio of an angle of bending the inner plate with respect to a rolling distance. Consequently, a wide range of chain bending angles can be achieved, while facilitating miniaturization of the chain based on a reduction in the sizes of the pin and the pin hole. This allows improvement of the applicability of the chain to rotary wheels with different winding diameters. 
         [0015]    According to the chain of the present invention set forth in claim  3 , the rolling surface length of the plate rolling surface is larger than the rolling surface length of the pin rolling surface. Thus, with the rolling of the pin permitted by making use of the formation of the opposite rolling surface, which rolls on the pin rolling surface, on the inner plate, which is larger than the pin, clearance in the pin hole can be more easily ensured. Furthermore, the chain can be bent using the entire rolling surface length of the pin rolling surface. This allows improvement of the applicability of the chain to rotary wheels with different winding diameters. 
         [0016]    According to the chain of the present invention set forth in claim  4 , the outer peripheral surface has a pin rear surface positioned opposite the pin rolling surface in the longitudinal direction and a pin connection surface that connects the pin rear surface and the pin rolling surface together on an opposite bending side. The pin connection surface is smaller than the pin rolling surface in radius of curvature. Thus, in the outer peripheral surface, the pin connection surface, which is continuous with the pin rolling surface, has a small radius of curvature. Consequently, possible interference between the outer peripheral surface and the hole peripheral wall surface during chain bending can be more easily avoided, while allowing the rolling surface length of the pin rolling surface to be set larger. This allows improvement of the applicability of the chain to rotary wheels with different winding radii. 
         [0017]    The chain of the present invention set forth in claim  5  is a silent chain disposed in a lubricant atmosphere wherein the holding plate is a guide plate, and the first link has one or more middle plates disposed adjacent to the inner plate between a pair of the guide plates in the width direction. Furthermore, the pin is inserted through the pin hole in the middle plate with a space formed between the pin hole and the pin rolling surface, and the space is positioned so as to overlap the plate rolling surface as viewed in the width direction. Thus, upon infiltrating to between the inner plate and the middle plate in the width direction and then reaching the space, a lubricant can be fed to the pin rolling surface and the plate rolling surface, that is, the contact areas of both rolling surfaces. Therefore, the lubricant fed from the space reduces the wear of both rolling surfaces, making the silent chain more durable. 
         [0018]    In connection with the present invention, the width direction is a chain width direction, and the longitudinal direction is a chain longitudinal direction. The width direction is a direction parallel to rotational center lines of rotary wheels or the axial direction of the pin. The longitudinal direction is a direction in which the chain extends along a plane orthogonal to the width direction. 
         [0019]    Furthermore, a side toward which the chain is bent when the chain meshes with the rotary wheels is hereinafter referred to as a bending side. A side opposite to the bending side is hereinafter referred to as an opposite bending side. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a plan view showing an important part of a silent chain according to an embodiment of the present invention, a part of the plan view being a cross-sectional view taken along a pitch plane; 
           [0021]      FIG. 2  is a cross-sectional view taken along line  2 - 2  in  FIG. 1 ; 
           [0022]      FIG. 3  is an enlarged view of a part  3  of  FIG. 2 ; and 
           [0023]      FIG. 4  is a diagram illustrating a state in which the silent chain in  FIG. 1  is wound and bent around a rotating sprocket, wherein  FIG. 4A ,  FIG. 4D , and  FIG. 4G  are side views of an important part,  FIG. 4B  and  FIG. 4C  are enlarged views of a part (b) and a part (c) of  FIG. 4A ,  FIG. 4E  and  FIG. 4F  are enlarged views of a part (e) and a part (f) of  FIG. 4D , and  FIG. 4H  and  FIG. 4I  are enlarged views of a part (h) and a part (i) of  FIG. 4G . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    A chain according to the present invention may be a silent chain, or instead of the silent chain, a link chain (including a roller chain) including a plurality of first links each including a pair of first link plates and a plurality of second links each including a pair of second link plates. 
         [0025]    The chain according to the present invention may be, instead of a transmission chain, a conveyance chain or an actuator chain. Thus, a chain apparatus including the chain may be a chain transmission apparatus, a chain conveyance apparatus, or any other apparatus. At least one rotary wheel around which the chain is wound may be used. 
         [0026]    The chain transmission apparatus including the chain according to the present invention may be used in an automotive power unit serving as a machine, for a power transmission apparatus or an engine providing the power unit, or may be used in a power unit other than the power units for automobiles or a machine other than the power units. For example, the chain may be provided in a continuously variable transmission for automobiles or a continuously variable transmission other than the continuously variable transmissions for automobiles. In this case, the rotary wheels are variable pulleys with a changeable wining radii. 
       Embodiment 
       [0027]    An embodiment of the present invention will be described below with reference to  FIG. 1  to  FIG. 4 . 
         [0028]    As shown in  FIG. 1  and  FIG. 2 , a silent chain (hereinafter referred to as a “chain”)  100  serving as a chain is an endless transmission chain provided in a chain transmission apparatus, according to the embodiment of the present invention. 
         [0029]    Besides the chain  100 , the chain transmission apparatus includes a sprocket mechanism serving as a winding mechanism and including sprockets  10  ( FIG. 4 ) serving as a plurality of rotary wheels around which the chain  100  is passed. The chain transmission apparatus is provided in a power transmission apparatus for an automotive power unit. 
         [0030]    The chain transmission apparatus is disposed in a chain chamber in the power unit. The chain  100  and the sprockets  10  are lubricated in a lubricant. Thus, a lubricating environment or a lubricant atmosphere based on a lubricant is present in the chain chamber. 
         [0031]    The chain  100  includes guide rows  101  serving as a plurality of first links, non-guide rows  103  serving as a plurality of second links, and a plurality of pins  140 . The guide row  101  and the non-guide row  103 , which are adjacent to each other in a longitudinal direction, are coupled together via the single pin  140  in a bendable manner. Each of all the guide rows  101  and each of all the non-guide rows  103  are alternately connected together in the longitudinal direction. 
         [0032]    Each of the guide rows  101  has a guide plates  110  serving as a pair of holding plates and one or more, in this case, a plurality of middle plates  120  disposed between the pair of guide plates  110  in the width direction. 
         [0033]    Each of the guide plates  110  includes holding holes  111  spaced from each other in the longitudinal direction and serving as a pair of pin holding portions. Each of the middle plates  120  includes a pair of first pin holes  121  and spaced from each other in the longitudinal direction and a pair of tooth portions  129  that is meshing portions capable of meshing with respective plurality of sprocket teeth  11  of the sprocket  10  ( FIG. 4 ). 
         [0034]    Each of the non-guide rows  103  has one or more, in this case, a plurality of inner plates  130  disposed in the width direction. The inner plate  130  includes a pair of second pin holes  131  spaced from each other in the longitudinal direction and a pair of tooth portions  139  that is meshing portions capable of meshing with the respective sprocket teeth  11  of the sprocket teeth  11 . 
         [0035]    The number of inner plates  130  in each of the non-guide rows  103  is larger than the number of middle plates  120  in each of the guide rows  101  by one. In the non-guide row  103 , all the inner plates  130  are arranged between the pair of guide plates  110  in the width direction and each lie adjacent to the middle plate  120  in the width direction. Every one or more of all the middle plates  120 , in an illustrated example, each of all the middle plates  120 , and every one or more of all the inner plates  130 , in the illustrated example, each of all the inner plates  130 , are alternately arranged in the width direction in a laminated manner. 
         [0036]    The holding holes  111 , the first pin holes  121 , and the second pin holes  131  are shaped surface-symmetrically with respect to central surfaces P1, P2, and P3, respectively, which cross the guide plate  110 , the middle plate  120 , and the inner plate  130 , respectively, in the longitudinal direction. The central surfaces P1 to P3 divide the longitudinal spacing between the pair of the holding holes  111 , the longitudinal spacing between the pair of first pin holes  121 , and the longitudinal spacing between the pair of second pin holes  131 , respectively, into two halves for each of the guide, middle, and inner plates  110 ,  120 , and  130 . 
         [0037]    For each of the plates  110 ,  120 , and  130 , a side toward which the chain  100  bends upon meshing with the sprocket  10  ( FIG. 4 ) with respect to a pitch plane Pp ( FIG. 2 ) is hereinafter referred to as a bending side, and a side opposite to the bending side is hereinafter referred to as an opposite bending side, for convenience of description. The holding holes  111  and the pin holes  121  and  131  are shaped surface-symmetrically with respect to the pitch plane Pp. 
         [0038]    The pitch plane Pp is a plane passing through an area where rolling surfaces  133  and  134 , which are described later, are in contact with each other, for the guide rows  101  connected together in alignment and included in a linear portion of the chain  100  that is a portion in a linear state and for the non-guide rows  103  connected together in alignment and also included in the linear portion. 
         [0039]    Furthermore, in any area in each of the plates  110 ,  120 , and  130 , a side relatively closer to the central surface P1, P2, or P3 is hereinafter referred to as a central surface side. A side relatively further from the central surface P1, P2, or P3 is hereinafter referred to as an opposite central surface side. 
         [0040]    The pins  140  are inserted into the holding holes  111 , the first pin holes  121 , and the second pin holes  131  arranged in the width direction in the guide rows  101  and the non-guide rows  103  arranged adjacently to one another in the longitudinal direction. In this state, each of the pins  140  is locked using locking means (for example, press fit or crimping) and is held in the holding holes  111  using coupling means (for example, press fit or engagement with the guide plates  110 ) in such a manner that rotational movement of the pin  140  is regulated, for example, disabled. Thus, the pin  140  is interposed in the holding holes  111  in a fixed state in which rotational movement of the pin  140  is regulated, in this case, disabled. 
         [0041]    On the other hand, the pin  140  is loosely fitted in the first and second pin holes  121  and  131  so as to be able to roll in the first and second pin holes  121  and  131  and is movably interposed in the first and second pin holes  121  and  131 . 
         [0042]    All the pins  140  in the chain  100  have the same shape. Furthermore, the pins  140  have the same cross-sectional shape at any position in the width direction. 
         [0043]    The cross-sectional shape is a shape obtained when a cutting plane is a plane orthogonal to the width direction. 
         [0044]    As shown in  FIG. 2  and  FIG. 3 , the pin  140  is press-fitted in the holding holes  111  in the guide plates  110 . 
         [0045]    A hole peripheral wall surface  122  forming the first pin hole  121  in the middle plate  120  is divided into a contact surface  123  that can be contacted by an outer peripheral surface  142  of the pin  140  and a noncontact surface  124  that constantly forms a space S between the noncontact surface  124  and the outer peripheral surface  142 . The first pin hole  121  is a circular hole with a circular cross section shaped like a single circle with one radius of curvature. 
         [0046]    The space S formed by inserting the pin  140  through the first pin hole  121  is positioned so as to overlap the entire plate rolling surface  133  in the second pin hole  131  as viewed in the width direction, and in a bent state, positioned so as to constantly overlap the contact areas of both rolling surfaces  133  and  143 . 
         [0047]    The circular shape or the circular arc shape means a single circle or circular arc with one radius of curvature or a composite circular arc including a plurality of circles or circular arcs with different radii of curvature. 
         [0048]    In the inner plate  130 , a hole peripheral wall surface  132  forming the second pin hole  131  is divided into the plate rolling surface  133  and a plate non-rolling surface. In the hole peripheral wall surface  132 , the plate rolling surface  133  is positioned opposite the central surface. 
         [0049]    The plate non-rolling surface has a longitudinally opposite surface  134  opposite to a pin rear surface  144  described below in the longitudinal direction, a pair of height opposite surfaces  135  and  136  which is continuous with the longitudinally opposite surface  134  on the bending side and on the opposite bending side and which is opposite to pin connection surfaces  145  and  146  described below in a height direction, and a pair of plate connection surfaces  137  and  138  that connects the plate rolling surface  133  to the pair of height opposite surfaces  135  and  136 , respectively, on the bending side and on the non-bending side. 
         [0050]    A gap ( FIG. 3 ) is formed between the height opposite surface  135  and the pin connection surface  145  and between the height opposite surface  136  and the pin connection surface  146  to enable relative bending of the guide row  101  and the non-guide row  103  based on relative rolling between the inner plate  130  and the pin  140 . The gap is omitted from  FIG. 2  and  FIG. 4  for convenience of drawing. 
         [0051]    The height direction is a chain height direction and is orthogonal to the width direction and the longitudinal direction and to the pitch plane Pp. 
         [0052]    The plate rolling surface  133  is a protruding curved surface. The longitudinally opposite surface  134 , the height opposite surfaces  135  and  136 , and the plate connection surfaces  137  and  138  are recessed curved surfaces. The plate rolling surface  133 , the longitudinally opposite surface  134 , the height opposite surfaces  135  and  136 , and the plate connection surfaces  137  and  138  each have a cross section shaped like a circular arc, in this case, a single circular arc. Thus, the plate non-rolling surface has a cross section shaped like a composite circular arc. 
         [0053]    The radius of curvature decreases in the following order: the height opposite surfaces  135  and  136 , the plate rolling surface  133 , the hole peripheral wall surface  122  of the first pin hole  121 , the longitudinally opposite surface  134 , and the plate connection surfaces  137  and  138 . 
         [0054]    The outer peripheral surface  142  of the pin  140  is divided into the pin rolling surface  143  and a pin non-rolling surface. 
         [0055]    The pin rolling surface  143  constantly forms a space S between the pin rolling surface  143  and the noncontact surface  124  of the first pin hole  121 . 
         [0056]    The pin non-rolling surface has the pin rear surface  144  that is constantly out of contact with the longitudinally opposite surface  134  and the height opposite surfaces  135  and  136 , and the pair of pin connection surfaces  145  and  146  that connects the pin rear surface  144  and the pin rolling surface  143  together on the bending side and on the non-bending side. The pin rear surface  144  is positioned opposite the pin rolling surface  143  in the longitudinal direction. 
         [0057]    The pin rolling surface  143 , the pin rear surface  144 , and the pin connection surfaces  145  and  146  are protruding curved surfaces. The pin rolling surface  143  and the pin non-rolling surface has a cross section shaped like a circular arc, in this case, a single circular arc. Thus, the pin rear surface  144  and the pair of pin connection surfaces  145  and  146  have the same radius of curvature. 
         [0058]    The radius of curvature decreases in the following order: the pin rolling surface  143 , the hole peripheral wall surface  122  of the first pin hole  121 , and the pin non-rolling surface. The radius of curvature of the pin rear surface  144  is equal to or larger than the radius of curvature of each of the pin connection surfaces  145  and  146 . In the illustrated example, the radius of curvature of the pin rear surface  144  is equal to the radius of curvature of each of the pin connection surfaces  145  and  146 , as described above. Thus, the radius of curvature of each of the pin connection surfaces  145  and  146  is smaller than the radius of curvature of the pin rolling surface  143 . 
         [0059]    Furthermore, the radii of curvature of the plate rolling surface  133  and the pin rolling surface  143  are the same in the illustrated example but may be different from each other. The radius of curvature of the longitudinally opposite surface  134  is larger than the radius of curvature of the pin rear surface  144 . 
         [0060]    Clearances C1, C2, and C3 are formed in the second pin hole  131  in order to permit the plate rolling surface  133  to roll on the pin rolling surface  143 . The clearance C1 is formed between the plate connection surface  137  and the pin connection surface  145  on the bending side, the clearance C2 is formed between the plate connection surface  138  and the pin connection surface  146  on the opposite bending side, and the clearance C3 is formed between the longitudinally opposite surface  134  and the pin rear surface  144 . 
         [0061]    The rolling surface length L3 of the plate rolling surface  133  is larger than the rolling surface length L4 of the pin rolling surface  143 . The rolling surface lengths L3 and L4 are the lengths of the plate rolling surface  133  and the pin rolling surface  143  in section. 
         [0062]    The plate rolling surface  133  and the pin rolling surface  143  are in contact with each other so as to be able to roll. During chain bending when the non-guide row  103  (that is, the inner plates  130 ) bends relative to the guide row  101  (that is, the guide plates  110  and the middle plates  120 ), the plate rolling surface  133  rolls on and relative to the pin rolling surface  143 . 
         [0063]    With reference to  FIG. 2  to  FIG. 4 , a chain bending state will be described in which the chain  100  is wound around the sprocket  10 . 
         [0064]    When the inner plates  130  of the chain ( FIG. 2 ) in the linear state start to bend ( FIG. 4A ), between the plate rolling surface  133  and the pin rolling surface  143 , the plate rolling surface  133  (that is, the inner plate  130 ) rolls relative to the pin rolling surface  143  (that is, the pin  140  and further the guide plate  110  and the middle plate  120 ) while involving substantially no sliding. 
         [0065]    The relative movement of the inner plate  130  and the pin  140  in the height direction by an amount larger than a predetermined movement amount as a result of the abutting contact between the tooth portions  129  and  139  and the sprocket teeth  11  is regulated by the contact between the height opposite surface  135  and the pin connection surface  145 , located opposite each other, and between the height opposite surface  136  and the pin connection surface  146 , located opposite each other. 
         [0066]    Then, as the bending of the chain  100  progresses sequentially as shown in  FIG. 4D  and  FIG. 4G , the plate rolling surface  133  further rolls on the pin rolling surface  143 . Thus, the inner plates  130 , which have started bending from the linear state, reach the maximum bending state to complete the bending. 
         [0067]    From the start of the bending of the inner plates  130  until the completion of the bending or during chain bending, the plate rolling surface  133  and the pin rolling surface  143  roll relative to each other in a contact state while involving substantially no sliding. Thus, the outer peripheral surface  142  of the pin  140  and the hole peripheral wall surface  132  of the inner plate  130  are in rolling contact with each other, reducing the friction between the outer peripheral surface  142  and the hole peripheral wall surface  132 . 
         [0068]    Furthermore, from the start till the completion of bending, the gaps between the height opposite surface  135  and the pin connection surface  145  and between the height opposite surface  136  and the pin connection surface  146  in the height direction are formed by setting the shapes of the pin connection surfaces  145  and  146  and the height opposite surfaces  135  and  135  so as to reduce the range of movement, in the height direction, of the inner plate  130  and the pin  140 , which roll relative to each other. This suppresses the sliding between the outer peripheral surface  142  of the pin  140  and the hole peripheral wall surface  132  of the inner plate  130 , reducing the friction between the pin  140  and the inner plate  130 . 
         [0069]    An embodiment obtained by modifying a part of the configuration of the above-described embodiment will be described in conjunction with description of the modified part. 
         [0070]    The plate rolling surface  133  may be positioned on the central surface side of the hole peripheral wall surface  132  or may be a recessed curved surface. 
         [0071]    The chain may be a roller chain in which the first link has a pair of outer plates serving as a pair of holding plates, whereas the second link has a pair of inner plates and in which the pin has a circular cross-sectional shape between the inner plates and supports a roller so that the roller is rotatable.