Abstract:
The invention provides a simple-structured tensioner lever capable of suppressing deflection of a stopper member and allows smooth assembly of the tensioner lever into an engine. The tensioner lever includes a stopper member for locking a coil spring, this stopper member including: a stopper pin portion inserted into a pin hole; a stopper front side extension portion continuous with one end of the stopper pin portion and protruding toward a base front surface; a stopper rear side extension portion continuous with the other end of the stopper pin portion and protruding toward a base rear surface; a spring lock portion formed in the stopper rear side extension portion and making engagement with a spring support arm; and a stopper movement restricting portion making engagement with the spring support arm to restrict movement of the spring support arm in a direction away from the base rear surface.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a tensioner lever that slidably guides a running chain, and more particularly to a chain tensioner lever that slidably guides a chain by pressing a shoe surface of a lever body against the chain by the elastic force of a coil spring. 
         [0003]    2. Description of the Related Art 
         [0004]    Tensioner levers used to remove slackness in chains and to prevent vibration of running chains have been known. One such tensioner lever in a conventional chain transmission used for an auxiliary machine or the like of a car engine is a tensioner lever  110  that is pivotally attached to an attachment surface of an engine block or the like and includes, as shown in  FIG. 8 , a lever body  120  having a shoe surface  120   a  that slidably guides the chain, and a coil spring  130  interposed between the lever body  120  and an attachment surface (not shown) to press the shoe surface  120   a  toward the chain (see, for example, Japanese Patent Application Laid-open No. 2012-36996). 
         [0005]    In such a tensioner lever  110 , as shown in  FIG. 8 , a spring helical part  131  of the coil spring  130  is loosely fitted on a boss  123  protruded from a base part of the lever body  120  toward the attachment surface. A spring pressing arm  132  extending from one end of the spring helical part  131  is in contact with the lever body  120 . 
         [0006]    With the tensioner lever  110  being attached to the attachment surface, a spring support arm  133  extending from the other end of the spring helical part  131  is inserted in a spring holder hole formed in the attachment surface. Before the tensioner lever  110  is attached to the attachment surface, i.e., during storage or transport, the spring support arm  133  is locked by a pin-like stopper member  140  inserted in a pin hole  126  of the lever body  120 . 
       SUMMARY OF THE INVENTION 
       [0007]    However, the coil spring  130  for pressing the lever body  120  of the tensioner lever  110  is designed to have a large spring force. When the tensioner lever  110  has been stored for a long time, with the stopper member  140  locking the coil spring  130 , the stopper member  140  may sometimes suffer a slight deflection in the direction indicated with reference symbol A in  FIGS. 8 and 9 , due to the pressure from the coil spring  130 . 
         [0008]    When such deflection occurs in the stopper member  140 , the spring support arm  133  may move, as guided by the deflected stopper member  140 , in a direction away from the base rear surface of the lever body  120  as indicated with reference symbol B in  FIGS. 8 and 9 . When this happens, the stopper member  140  may be pressed by the spring support arm  133  at a position away from a stopper pin portion (not shown) inserted in the pin hole  126 , which will cause the stopper member  140  to deflect even more. 
         [0009]    There was a problem that such a stopper member  140  that had undergone a large deflection would not allow it to be easily drawn out from the pin hole  126  when the tensioner lever  110  was to be mounted in the engine. 
         [0010]    An object of the present invention is to solve these problems and to provide a simple-structured tensioner lever that can minimize deflection of a stopper member to realize smooth assembly thereof into an engine. 
         [0011]    The present invention provides a tensioner lever including a lever body having a shoe surface for slidably guiding a chain; a coil spring interposed between the lever body and an attachment surface of a mounting target to press the shoe surface toward the chain; and a stopper member that locks the coil spring. The lever body includes a base part, a shaft hole extending from a base front surface through a base rear surface of the base part, a cylindrical boss protruding from a peripheral edge of the shaft hole on the base rear surface, and a pin hole extending from the base front surface through the base rear surface. The coil spring includes a spring helical part disposed on the boss, a spring pressing arm extending from one end of the spring helical part and making contact with the lever body, and a spring support arm extending from the other end of the spring helical part and supported on the attachment surface. The stopper member includes a stopper pin portion inserted into the pin hole, a stopper front side extension portion continuous with one end of the stopper pin portion and protruding to a base front surface side, a stopper rear side extension portion continuous with the other end of the stopper pin portion and protruding to a base rear surface side, a spring lock portion formed to the stopper rear side extension portion and making engagement with the spring support arm, and a stopper movement restricting portion making engagement with the spring support arm to restrict movement of the spring support arm in a direction away from the base rear surface. The problems described above are thereby solved. 
         [0012]    According to one aspect of the present invention, the stopper member includes a stopper movement restricting portion making engagement with the spring support arm to restrict movement of the spring support arm in a direction away from the base rear surface. This can prevent a situation wherein the spring support arm moves away from the base rear surface and pushes the stopper rear side extension portion at a position away from the stopper pin portion inserted in the pin hole. Thus the stopper rear side extension portion is prevented from being deflected largely. This way, the removability of the stopper member from the lever body can be preserved, and the tensioner lever can be smoothly mounted into the engine. 
         [0013]    According to another aspect of the present invention, a stopper movement restricting portion is provided to the stopper front side extension portion that extends from the base front surface side toward the base rear surface side along an outer side of a base side face. Unlike a configuration wherein the stopper movement restricting portion is provided to the stopper front side extension portion, the stopper movement restricting portion need not pass through the pin hole of the lever body when the stopper member is drawn out of the lever body, so that a certain degree of freedom in design of the stopper movement restricting portion can be ensured. 
         [0014]    According to yet another aspect of the present invention, the stopper movement restricting portion is formed to the stopper rear side extension portion and in a step-like shape that makes engagement with the spring support arm. Such a step-like stopper movement restricting portion can be formed through simple processing such as providing a recess in an outer circumferential surface of the stopper rear side extension portion, or bending the stopper rear side extension portion, so that the processing cost for the stopper member can be reduced. 
         [0015]    According to a further aspect of the present invention, the stopper member is formed such as to be turned about the stopper pin portion inserted in the shaft hole to cause the stopper movement restricting portion to make engagement with a rear side of the spring support arm. To remove the stopper member, the stopper member is turned so as to disengage the stopper movement restricting portion from the spring support arm, after which the stopper member is drawn out toward the base front surface side. Since the stopper member can be removed by such a simple operation, the tensioner lever can be easily mounted into the engine. 
         [0016]    According to another aspect of the present invention, the stopper operating bent portion includes a portion that is located farther away from the stopper pin portion in an axial direction thereof than a distance between the stopper pin portion and the stopper movement restricting portion. Therefore, the stopper movement restricting portion can be engaged with and disengaged from the spring support arm with a small force by the use of leverage. 
         [0017]    According to yet another aspect of the present invention, the first end and the second end of the stopper operating bent portion are disposed to face each other in a rotating direction of the stopper member about the stopper pin portion. When the stopper operating bent portion is turned to cause the stopper movement restricting portion to be engaged or disengaged, the first end and the second end of the stopper operating bent portion contact each other and thereby favorably transmit the torque of the stopper operating bent portion to the stopper movement restricting portion. 
         [0018]    According to a further aspect of the present invention, the portion where the first end and the second end of the stopper operating bent portion face each other has a length set larger than a cross-sectional diameter of the stopper operating bent portion. When the stopper operating bent portion is turned to cause the stopper movement restricting portion to be engaged or disengaged, the first end and the second end of the stopper operating bent portion are kept in good contact with each other and thereby reliably transmit the torque of the stopper operating bent portion to the stopper movement restricting portion. 
         [0019]    According to another aspect of the present invention, the stopper member is formed such as to be turned about the stopper pin portion in a same direction as the direction in which the lever body is biased by the spring pressing arm about the spring helical part, so as to cause the stopper movement restricting portion to be disengaged from the spring support arm. Therefore, when the stopper member is turned to disengage the stopper movement restricting portion from the spring support arm, the lever body is prevented from turning about the pivot shaft inserted in the shaft hole together with the rotating stopper member, so that the stopper member alone can reliably be turned relative to the lever body. That is, when the tensioner lever is installed in the engine, the chain is in contact with the shoe surface of the lever body, so that the lever body is restricted by the chain from rotating in the direction in which the lever body is biased by the spring pressing arm. Therefore, the lever body is prevented from turning with the rotation of the stopper member. 
         [0020]    According to yet another aspect of the present invention, the stopper front side extension portion includes an opposite portion located opposite and in front of the base front surface. Since the base front surface and the spring support arm can be sandwiched in the front to back direction by the opposite portion located opposite and in front of the base front surface and the stopper movement restricting portion disposed on the rear side of the spring support arm, the spring support arm can be reliably prevented from moving toward the rear side. 
         [0021]    According to a further aspect of the present invention, the opposite portion of the stopper front side extension portion has a length set larger than a cross-sectional diameter of the opposite portion, so that the base front surface and the opposite portion can be kept in good contact with each other, and the opposite portion and the stopper movement restricting portion can stably sandwich the base front surface and the spring support arm. 
         [0022]    According to another aspect of the present invention, the stopper front side extension portion includes a stopper operating bent portion that can be operated by a user, so that various operations such as turning the stopper member about the stopper pin portion inserted in the shaft hole of the lever body, and drawing out the stopper member toward the base front surface side, can be easily performed with the use of the stopper operating bent portion, which can be formed by bending a pin-like material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a diagram illustrating one form of use of a tensioner lever according to a first embodiment of the present invention viewed from an attachment surface side; 
           [0024]      FIG. 2  is a perspective view illustrating the tensioner lever; 
           [0025]      FIG. 3  is a perspective view illustrating the tensioner lever seen from a different angle from the angle of  FIG. 2 ; 
           [0026]      FIG. 4  is a perspective view illustrating a stopper member in the first embodiment; 
           [0027]      FIG. 5  is a perspective view illustrating a tensioner lever according to a second embodiment of the present invention; 
           [0028]      FIG. 6  is a perspective view illustrating a stopper member in the second embodiment; 
           [0029]      FIG. 7  is a perspective view illustrating a variation example of the stopper member in the second embodiment; 
           [0030]      FIG. 8  illustrates a conventional tensioner lever for reference; and 
           [0031]      FIG. 9  illustrates the conventional tensioner lever seen from a different angle from the angle of  FIG. 8  for reference. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    A tensioner lever  10  according to a first embodiment of the present invention will be hereinafter described with reference to the drawings. 
         [0033]    The tensioner lever  10 , as shown in  FIG. 1 , is pivotably mounted on a pivot shaft P protruding from an attachment surface (not shown) of an object to which the tensioner lever is mounted, such as an engine block (not shown), so as to slidably guide a chain CH running between a plurality of sprockets S to keep an appropriate chain tension. 
         [0034]    As shown in  FIGS. 1 and 2 , the tensioner lever  10  includes a lever body  20  made of a synthetic resin or the like, a coil spring  30  made of metal or the like, and a stopper member  40  made of metal or the like. 
         [0035]    The lever body  20  includes, as shown in  FIGS. 2 and 3 , a planar base part  21  disposed a certain distance away from the attachment surface, a lever circumferential wall  22  standing upright from the peripheral edge of the base part  21  toward the attachment surface, a cylindrical boss  23  protruding from the peripheral edge of a shaft hole  21   a  formed in the base part  21  toward the attachment surface (toward a base rear surface  21   c  side), a plurality of reinforcing ribs  24  formed between a chain-side circumferential wall  22   a  and a non-chain-side circumferential wall  22   b  of the lever circumferential wall  22 , a spring lock portion  25  that protrudes from an inner surface of the chain-side circumferential wall  22   a  for locking a spring pressing arm  32  of the coil spring  30 , and a pin hole  26  for the stopper member  40  to be inserted. 
         [0036]    The shaft hole  21   a  extends from a base front surface  21   b  through the base rear surface  21   c  of the base part  21 , and the pin hole  26  extends from the base front surface  21   b  through the base rear surface  21   c.    
         [0037]    A shoe surface  20   a  that slidably guides the chain CH is formed on a side face of the lever body  20  facing the chain CH (outer surface of the chain-side circumferential wall  22   a ). 
         [0038]    The pivot shaft P is inserted into the shaft hole  21   a  and the boss  23  of the base part  21 , whereby the lever body  20  is pivotably (rotatably) supported on the attachment surface. 
         [0039]    The lever circumferential wall  22  includes the chain-side circumferential wall  22   a  disposed on the chain CH side and the non-chain-side circumferential wall  22   b . The chain-side circumferential wall  22   a  includes a cut-out region in a portion facing the spring helical part  31  of the coil spring  30 . 
         [0040]    The end face of the boss  23  on the attachment surface side is formed to protrude slightly more toward the attachment surface than the lever circumferential wall  22 , which prevents other parts than this end face of the boss  23  on the attachment surface side from contacting the attachment surface, so that smooth pivoting (rotation) of the lever body  20  about the pivot shaft P is ensured. 
         [0041]    A restricting protrusion  23   b  is formed on the outer circumferential surface  23   a  of the boss at the end on the attachment surface side to restrict the movement of a spring helical part  31  disposed on the outer circumferential surface  23   a  of the boss toward the attachment surface side. This way, in a state before the tensioner lever  10  is attached to the attachment surface, the coil spring  30  is prevented from coming off of the lever body  20 , and also, in a state where the tensioner lever  10  is attached to the attachment surface, the coil spring  30  is prevented from interfering with the attachment surface. 
         [0042]    The coil spring  30  is interposed between the lever body  20  and the attachment surface when the tensioner lever  10  is attached to the attachment surface as shown in  FIGS. 1 and 2  to press the shoe surface  20   a  of the lever body  20  toward the chain CH by the elastic force it generates. As shown in  FIGS. 2 and 3 , the coil spring includes the spring helical part  31 , the spring pressing arm  32  extending from one end of the spring helical part  31 , and a spring support arm  33  extending from the other end of the spring helical part  31 . 
         [0043]    The spring helical part  31  loosely fits on the outer circumferential surface  23   a  of the boss  23 , i.e., is disposed with a gap between itself and the outer circumferential surface  23   a  of the boss, as shown in  FIGS. 2 and 3 . 
         [0044]    The spring pressing arm  32  is disposed such that part of it is in contact with an inner surface of the chain-side circumferential wall  22   a.    
         [0045]    The spring support arm  33  has a distal end that is bent toward the attachment surface. When the tensioner lever  10  is attached to the attachment surface, the distal end of the spring support arm  33  is inserted in and supported by a spring holder hole (not shown) formed in the attachment surface. Before the tensioner lever  10  is attached to the attachment surface, the spring support arm is locked by the stopper member  40  as shown in  FIG. 2 . 
         [0046]    The stopper member  40  is inserted in the pin hole  26  of the lever body  20  to temporarily lock the spring support arm  33 , as shown in  FIGS. 2 and 3 , in a state before the tensioner lever  10  is attached to the attachment surface. When the tensioner lever  10  is attached to the attachment surface, the stopper member  40  has been pulled out from the pin hole  26  and removed as shown in  FIG. 1 . 
         [0047]    The stopper member  40  is formed from a rod-like material that is bent, and includes, as shown in  FIG. 2  to  FIG. 4 , a straight stopper pin portion  41  inserted into the pin hole  26  of the lever body  20 , a stopper front side extension portion  42  continuous with one end of the stopper pin portion  41  and protruding to the base front surface  21   b  side, and a stopper rear side extension portion  43  continuous with the other end of the stopper pin portion  41  and protruding to the base rear surface  21   c  side. 
         [0048]    The stopper front side extension portion  42  is formed from a rod-like material and bent, as shown in  FIGS. 2 and 3 , such as to extend from the base front surface  21   b  side toward the base rear surface  21   c  side along the outer side of a base side face  21   d  of the base part  21 . 
         [0049]    The stopper front side extension portion  42  includes, as shown in  FIGS. 2 to 4 , a stopper operating bent portion  42   a  continuous with one end of the stopper pin portion  41 , and a stopper movement restricting portion  42   e  provided at a portion on the base rear surface  21   c  side. 
         [0050]    The stopper operating bent portion  42   a  is formed in an arcuate, ring-like shape so that a user&#39;s finger can be inserted. The specific shape of the stopper operating bent portion  42   a  is not limited to the one described above. The bent portion may have, for example, a shape that allows the user to pinch it to operate the stopper member  40 . 
         [0051]    The stopper operating bent portion  42   a  includes, as shown in  FIGS. 3 and 4 , a first end  42   b  that is one end continuous with the stopper tin portion  41 , and a second end  42   c  that is the other end. The first end  42   b  and the second end  42   c  are located to face each other in a rotating direction of the stopper member  40  about the stopper pin portion  41 . 
         [0052]    The length of a portion where these first end  42   b  and second end  42   c  face each other (i.e., length in the longitudinal direction of the pin-like material of the stopper member  40 ) is set larger than the cross-sectional diameter of the stopper operating bent portion  42   a  (i.e., cross-sectional diameter of the pin-like material of the stopper member  40 ). 
         [0053]    The stopper operating bent portion  42   a  further includes a portion that is located farther away from the stopper pin portion  41  in an axial direction thereof than the distance between the stopper pin portion  41  and the stopper movement restricting portion  42   e.    
         [0054]    The stopper movement restricting portion  42   e  makes engagement with the rear side of the spring support arm  33  on the base rear surface  21   c  side as shown in  FIG. 2 , so as to restrict the movement of the spring support arm  33  rearward, i.e., in the direction away from the base rear surface  21   c.    
         [0055]    The stopper movement restricting portion  42   e  is positioned to intersect the spring support arm  33  at an angle α of 90° or more as shown in  FIG. 2 , so that the stopper movement restricting portion  42   e  is prevented from being accidentally disengaged from the spring support arm  33 . 
         [0056]    The stopper front side extension portion  42  includes an opposite portion  42   d  that is located opposite and in front of the base front surface  21   b  as shown in  FIG. 3 . In this embodiment, the first end  42   b  of the stopper operating bent portion  42   a  functions as the opposite portion  42   d.    
         [0057]    The length of the opposite portion  42   d  facing the base front surface  21   b  (i.e., length in the longitudinal direction of the pin-like material of the stopper member  40 ) is set larger than the cross-sectional diameter of the opposite portion  42   d  (i.e., cross-sectional diameter of the pin-like material of the stopper member  40 ). 
         [0058]    The stopper rear side extension portion  43  is formed continuous with the stopper pin portion  41  and straight as shown in  FIGS. 2 and 4 . Part of the stopper rear side extension portion  43  functions as a spring lock portion  43   a  that makes engagement with the spring support arm  33 . 
         [0059]    Next, how to remove the stopper member  40  from the lever body  20  will be described below. 
         [0060]    First, the user inserts a finger into the stopper operating bent portion  42   a  and turns the stopper member  40  about the stopper pin portion  41  inserted in the shaft hole  21   a , whereby the stopper movement restricting portion  42   e  is disengaged from the rear side of the spring support arm  33 . 
         [0061]    In this embodiment, to disengage the stopper movement restricting portion  42   e , the stopper member  40  is turned in the same direction as that (clockwise in  FIG. 2 ) in which the lever body  20  is biased by the spring pressing arm  32  about the spring helical part  31 . Instead, the stopper member  40  may be configured to be turned in the opposite direction from that of the lever body  20  in which it is biased by the spring pressing arm  32  about the spring helical part  31 . 
         [0062]    Next, the stopper member  40  is pulled to the base front surface  21   b  side so that the stopper pin portion  41  and the stopper rear side extension portion  43  are drawn out of the pin hole  26  in the lever body  20 , and thus the stopper member  40  is removed. 
         [0063]    Next, a tensioner lever  10  according to a second embodiment of the present invention will be described with reference to  FIGS. 5 to 7 . The second embodiment is, in part, exactly the same as the previously described first embodiment, and therefore its configurations will not be described except for the differences. 
         [0064]    In the tensioner lever  10  of the first embodiment, the stopper movement restricting portion  42   e  that restricts movement of the spring support arm  33  toward the rear side is formed to the stopper front side extension portion  42 . In the tensioner lever  10  of the second embodiment, a stopper movement restricting portion  43   b  is formed to the stopper rear side extension portion  43 . 
         [0065]    More specifically, in the second embodiment, as shown in  FIGS. 5 and 6 , a recess is formed in an outer circumferential surface of the stopper rear side extension portion  43 , and the bottom of this recess functions as the spring lock portion  43   a , while an inner side face of this recess functions as the step-like stopper movement restricting portion  43   b  that makes engagement with the rear side of the spring support arm  33 . 
         [0066]    The stopper movement restricting portion  43   b  is not limited to the specific form described above, and may be formed, for example, by bending the stopper rear side extension portion  43  as shown in  FIG. 7 . In this case, the pin hole  26  in the lever body  20  may be formed to have an oval cross-sectional shape. 
         [0067]    While the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments and may be carried out with various design changes without departing from the scope of the present invention set forth in the claims. 
         [0068]    For example, while the tensioner lever was described as a component to be incorporated in a timing system of an engine in the embodiments above, the tensioner lever can be applied to various other equipment other than this. 
         [0069]    The chain tensioner may not necessarily be applied to a chain transmission mechanism but also used for similar transmission mechanisms that use belts, ropes and the like, and can be applied in a variety of industrial fields. 
         [0070]    In the embodiments described above, the pivot shaft protruding from the attachment surface of an engine block or the like is inserted into the shaft hole in the lever body. Instead, a bolt or the like inserted into the shaft hole of the lever body may be attached to the attachment surface of an engine block or the like.