Patent Document

CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority from Japanese Patent Application No. 2014-234419 filed on Nov. 19, 2014, the entire contents of which are herein incorporated by reference. 
       FIELD 
       [0002]    The present invention relates to a recoil starter in which a rope reel is rotated by pulling a recoil rope, and the rotation of the rope reel is transmitted to a driving pulley connected to a crankshaft of an engine via a ratchet mechanism, thereby starting the engine. 
       BACKGROUND 
       [0003]    A recoil starter may have a ratchet mechanism (for example, see JP-2012-132430-A and JP-2014-132159-A). In such recoil starter, a rope reel rotates in an engine starting direction by pulling a recoil rope. When the rope reel rotates in the engine starting direction, a ratchet provided thereon swings to the outer diameter direction to be engaged with the driving pulley, so that the rotation of the rope reel can be transmitted to the engine side. When the recoil rope is released, the rope reel rotates in a direction opposite to the engine starting direction by restoring force of a recoil spiral spring or the like, the ratchet swings to the inner diameter direction to be disengaged from the driving pulley so that the rotation on the engine side is not transmitted to the rope reel side after the engine starts. A spring may be used to retract the ratchet, that is, the spring may be disposed to push back the ratchet to the inner diameter direction when the recoil rope is released. 
         [0004]    After the ratchet has been pushed back to the inner diameter direction by the urging force of the spring, force may be unintentionally exerted on the ratchet due to vibration or the like, and the ratchet may be unintentionally moved. If the ratchet is unintentionally moved and engaged with the driving pulley, the ratchet may be damaged or broken. 
       SUMMARY 
       [0005]    One object of the present invention is to provide a recoil starter capable of holding a ratchet reliably in a retracted position when a rope reel rotates in a direction opposite to an engine starting direction. 
         [0006]    A first aspect of the invention provides 
         [0007]    a recoil starter including: 
         [0008]    a reel support shaft; 
         [0009]    a rope reel that is rotatably mounted on the reel support shaft; 
         [0010]    a ratchet member that is swingably mounted on the rope reel; 
         [0011]    a ratchet guide that is rotatably mounted on the reel support shaft with friction resistance; and 
         [0012]    a friction spring that provides the friction resistance to the ratchet guide, 
         [0013]    wherein the ratchet guide includes:
       a guide portion that pushes out the ratchet member to an outer diameter direction when the rope reel rotates in an engine starting direction; and   a swinging-prevention portion that prevents the ratchet member from swinging to the outer diameter direction when the ratchet member does not contact the guide portion.       
 
         [0016]    A second aspect of the invention provides, based on the above configuration, 
         [0017]    the recoil starter, 
         [0018]    wherein the ratchet guide is mounted on the reel support shaft at a side close to the engine as compared with the rope reel, and retains the rope reel with respect to the reel support shaft. 
         [0019]    A third aspect of the invention provides, based on the above configuration, 
         [0020]    the recoil starter, 
         [0021]    wherein the guide portion is disposed to push out a forward end portion of the ratchet member to the outer diameter direction, and 
         [0022]    the swinging-prevention portion is disposed to face a rearward end portion of the ratchet member. 
         [0023]    A fourth aspect of the invention provides, based on the above configuration, 
         [0024]    the recoil starter, 
         [0025]    wherein the ratchet guide includes a consecutive wall portion, and the consecutive wall portion form the guide portion and the swinging-prevention portion. 
         [0026]    According to the first aspect, the ratchet guide includes the guide portion that pushes out the ratchet member to the outer diameter direction when the rope reel rotates in the engine starting direction, and the swinging-prevention portion that prevents the ratchet member from swinging to the outer diameter direction when the ratchet member does not contact the guide portion. Thus, the recoil starter is capable of reliably holding the ratchet member at a retracted position when the rope reel rotates in a direction opposite to the engine starting direction. 
         [0027]    According to the second aspect, the ratchet guide further functions as a retainer that retains the rope reel with respect to the reel support shaft. Thus, one part, that is the ratchet guide, can provide at least three functions, so that the above-described effect can be obtained with a small number of parts count. 
         [0028]    According to the third aspect, the guide portion is disposed to guide the forward end portion of the ratchet member to be engaged with the driving pulley, and the swinging-prevention portion is disposed to face the rearward end portion of the ratchet member. With this structure, even when the guide portion and the swinging-prevention portion are placed closely with each other, the ratchet member does not easily interfere with the swinging-prevention portion when swinging to the outer diameter direction, and does not easily interfere with the guide portion when swinging to the inner diameter direction. That is, the guide portion and the swinging-prevention portion can be placed closely with each other, and it is possible to reduce a free running distance until the ratchet member is engaged with a driving pulley from when the rope reel is rotated to start the engine can be reduced. 
         [0029]    According to the fourth aspect, the guide portion and the swinging-prevention portion are provided as parts of the consecutive wall portion. Thus, the ratchet guide can be strengthened by the consecutive wall portion. Even when the ratchet receives unintentional force from the driving pulley, the ratchet can be supported by the consecutive wall portion. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0030]      FIG. 1  is a cross-sectional view of a recoil starter. 
           [0031]      FIG. 2A  is a front view of a ratchet member.  FIG. 2B  is a side view of the same. 
           [0032]      FIG. 3A  is a front view of a ratchet guide.  FIG. 3B  is a cross-sectional view of the ratchet guide taken along the line A-A of  FIG. 3A .  FIG. 3C  is a back view of the ratchet guide. 
           [0033]      FIGS. 4A and 4B  are explanatory views the operations of the ratchet member and the ratchet guide. 
           [0034]      FIGS. 5A and 5B  are explanatory views the operations of the ratchet member and the ratchet guide. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    An embodiment will be described with reference to the drawings. 
         [0036]    As shown in  FIG. 1 , a recoil starter  10  according to the embodiment includes a starter case  11 , a rope reel  15 , the recoil rope  16 , a recoil spiral spring  19 , ratchet members  20 , ratchet urging members  21 , a driving pulley  18 , a ratchet guide  22  and a friction spring  17 . The rope reel  15  is rotatably mounted on the starter case  11 . The recoil rope  16  is wound on a periphery of the rope reel  15 . The recoil spiral spring  19  is disposed in the starter case  11  to urge the rope reel  15  in a direction of rewinding the recoil rope  16 . The ratchet members  20  are swingably mounted on the rope reel  15 , and the ratchet urging members  21  are disposed to urge the ratchet members  20  toward their retracted positions. The driving pulley  18  is attached to a crankshaft of an engine, and is engageable with the ratchet members  20 . The ratchet guide  22  is rotatably mounted on the starter case  11 , and the friction spring  17  urges the ratchet guide  22  to thereby provide friction resistance to the ratchet guide  22 . 
         [0037]    As shown in  FIG. 1 , the recoil starter  10  may be mounted on a side surface portion of the engine (although not illustrated, the crankshaft of the engine exists on the left side in  FIG. 1 ). The starter case  11  generally accommodates the components of the recoil starter  10 . A reel support shaft  12  protrudes from the starter case  11 . When the recoil starter  10  is mounted on the engine, the reel support shaft  12  faces the crankshaft of the engine. The rope reel  15  and the ratchet guide  22  are mounted on the reel support shaft  12 , and a set screw  13  and a washer  14  are attached to a distal end of the reel support shaft  12  to thereby hold the rope reel  15  and the ratchet guide  22 . The recoil starter  10  may be mounted on other portion of the engine than the side surface portion, depending on an arrangement of the engine, as long as the rotational force can be transmitted to the crankshaft of the engine. 
         [0038]    The rope reel  15  has a wheel shape. A rope retention groove  15   a  is formed on a periphery of the rope reel  15 . The recoil rope  16  is wound on the rope retention groove  15   a  of the rope reel  15 . The rope reel  15  has a hole at a center thereof, and is rotatably mounted on the reel support shaft  12  such that the reel support shaft  12  passes through the center hole. Protrusions  15   b  are provided on eccentric positions on the rope reel  15 , and the ratchet members  20  are mounted on the protrusions  15   b.  In this embodiment, the rope reel  15  has two protrusions  15   b,  and two ratchet members  20  are mounted thereon. 
         [0039]    The recoil rope  16  is wound on the rope retention groove  15   a  of the rope reel  15 . While one end of the recoil rope  16  is fixed to the rope reel  15 , the other end is drawn out of the starter case  11  through an opening (not illustrated) provided to the starter case  11 . By pulling the drawn-out recoil rope  16 , the rope reel  15  is rotated on the reel support shaft  12  as a rotational axis, and the rotational force is transmitted to the engine to thereby start the engine. 
         [0040]    The recoil spiral spring  19  is disposed between the starter case  11  and the rope reel  15 . While one end of the recoil spiral spring  19  is fixed to the rope reel  15 , the other end is fixed to the starter case  11 . When the recoil rope  16  is pulled to rotate the rope reel  15 , the rotational force is accumulated in the recoil spiral spring  19 , and when the recoil rope  16  is released, the rotational force accumulated in the recoil spiral spring  19  rotates the rope reel  15  to thereby rewind the recoil rope  16 . 
         [0041]    The ratchet members  20  have a pawl shape, and are swingably mounted on the rope reel  15 . The ratchet members  20  are fitted onto the protrusions  15   b  of the rope reel  15  so as to be swingable around the protrusions  15   b  within a given angular range. As shown in  FIGS. 2A and 2B , each of the ratchet members  20  includes a hole as a swinging shaft portion  20   a  to receive the protrusion  15   b  of the rope reel  15 , a forward end portion  20   b  disposed on one side of the swinging shaft portion  20   a,  and a rearward end portion  20   c  disposed on the other side of the swinging shaft portion  20   a.  The “forward” direction corresponds to the rotational direction (the counter-clockwise direction in  FIGS. 4A to 5B ) of the rope reel  15  when the recoil rope  16  is pulled, and the “rearward” direction corresponds to the rotational direction (the clockwise direction in  FIGS. 4A to 5B ) of the rope reel  15  when the recoil rope  16  is rewound. The forward end portion  20   b  protrudes to the outer diameter direction of the rope reel  15  to be engaged with the driving pulley  18  when the rope reel  15  rotates. When the forward end portion  20   b  moves to the outer diameter direction, the rearward end portion  20   c  on the opposite side moves to the inner diameter direction. 
         [0042]    The ratchet members  20  are urged by the ratchet urging members  21 . For example, the ratchet urging members  21  are configured by torsional coil springs. Thus, when the recoil starter  10  does not operate, the forward end portions  20   b  are brought into a state (the retracted position) of not protruding from the rope reel  15  as viewed from the direction of the rotational axis of the rope reel  15 . This state is shown in  FIG. 4A . 
         [0043]    The driving pulley  18  is mounted on the crankshaft of the engine. The rotational force of the rope reel  15  is transmitted to the engine side through the driving pulley  18 . As shown in  FIG. 1 , the driving pulley  18  includes receiving portions  18   a  that are disposed at regular intervals in the circumferential direction. The receiving portions  18   a  of the driving pulley  18  are engageable with the forward end portions  20   b  of the ratchet members  20 . 
         [0044]    As shown in  FIGS. 3A to 3C , the ratchet guide  22  generally has a circular shape. The ratchet guide  22  is rotatably mounted on the reel support shaft  12  with friction resistance, which is provided by the friction spring  17 . 
         [0045]    As shown in  FIGS. 3A to 3C , the ratchet guide  22  according to this embodiment includes a flange portion  23  having a circular disc shape, and a concave portion  26  disposed in the center of the flange portion  23 . 
         [0046]    Rib-like wall portions protrude in the thickness direction from the back surface of the flange portion  23 . In this embodiment, each of the wall portions forms a guide portion  24  and a swinging-prevention portion  25 . The guide portion  24  is formed to guide the forward end portions  20   b  of the ratchet members  20  to the outside (the outer diameter direction) of the rope reel  15  when the rope reel  15  rotates in the engine starting direction. The swinging-prevention portions  25  is formed to prevent the ratchet members  20  from swinging to the outside (the outer diameter direction) of the rope reel  15  when the ratchet members  20  do not contact the guide portions  24 . In this embodiment, the swinging-prevention portion  25  is formed as a part of the wall portion which extends in the circumferential direction around the axis of the ratchet guide  22 . 
         [0047]    The concave portion  26  of the ratchet guide  22  is provided with a through hole  28  in its center. In the assembled state, the reel support shaft  12  is inserted into the through hole  28 . A part of the concave portion  26  is stepped to form a retaining portion  27 . As shown in  FIG. 1 , in the assembled state, the retaining portion  27  faces the rope reel  15 , thereby functioning as a retainer of the rope reel  15  with respect to the reel support shaft  12 . Inside the concave portion  26 , a spring-receiving portion  29  is provided to receive the friction spring  17 . 
         [0048]    The friction spring  17  is disposed between the starter case  11  and the ratchet guide  22 , and urges the ratchet guide  22  in a direction of being away from the starter case  11 . Since the friction spring  17  urges the ratchet guide  22  toward the washer  14 , predetermined friction resistance is provided to the ratchet guide  22 . 
         [0049]    The operation of the above-described recoil starter  10  will be described below. 
         [0050]      FIG. 4A  shows the original state. When the recoil rope  16  is pulled from the original state in order to start the engine, the rope reel  15  rotates in the engine starting direction, and the ratchet members  20  rotate integrally with the rope reel  15 . On the other hand, the ratchet guide  22  does not immediately rotate with the rope reel  15  because of the friction resistance provided between the ratchet guide  22  and the reel support shaft  12 . As the ratchet guide  22  and the rope reel  15  rotate relatively, the forward end portions  20   b  of the ratchet members  20  contact the guide portions  24  of the ratchet guide  22  as shown in  FIG. 4B . And, as the ratchet members  20  further rotate together with the rope reel  15 , the forward end portions  20   b  of the ratchet members  20  are pressed onto the guide portions  24  of the ratchet guide  22 , and are caused to swing and protrude to the outer diameter direction as shown in  FIG. 5A . When the ratchet guide  22  and the rope reel  15  relatively rotate to the position shown in  FIG. 5B , the ratchet guide  22  is locked by the rope reel  15  (the ratchet members  20 ), so that the ratchet guide  22  thereafter integrally rotates with the rope reel  15  against the friction resistance by the friction spring  17 . 
         [0051]    When the forward end portions  20   b  of the ratchet members  20  protrude to the outer diameter direction, the forward end portions  20   b  are engageable with the receiving portions  18   a  of the driving pulley  18 . Thus, the driving pulley  18  also rotates integrally with the rope reel  15 . As a result, the rotational force of the rope reel  15  can be transmitted to the driving pulley  18  (the engine side), thereby starting the engine. 
         [0052]    When pulling of the recoil rope  16  is finished, the rope reel  15  is rotated backward (rotated clockwise) from the state shown in  FIG. 5B  by the rotational force accumulated in the recoil spiral spring  19 . Thus, the ratchet guide  22  and the rope reel  15  rotate relatively in the direction opposite to the previous rotation direction (the engine starting direction), the forward end portions  20   b  of the ratchet members  20  are separated from the guide portions  24 , and the ratchet members  20  swing inwardly by the urging force of the ratchet urging members  21 . With this operation, the ratchet members  20  swing until the ratchet members  20  return to the retracted position, as shown in  FIG. 4A . 
         [0053]    After the forward end portions  20   b  of the ratchet members  20  are separated from the guide portions  24  of the ratchet guide  22 , force may be unintentionally exerted on the forward end portions  20   b  of the ratchet members  20  toward the outer diameter direction due to vibration or the like of the machine to which the recoil starter  10  is mounted. However, in this embodiment, even if such force is exerted, the ratchet members  20  can be reliably held at a retracted position because the swinging-prevention portions  25  are disposed at positions facing the rearward end portions  20   c  of the ratchet members  20  so as to prevent the forward end portions  20   b  of the ratchet members  20  from swinging outwardly, as shown in  FIG. 4A . 
         [0054]    In this embodiment, the guide portions  24  are disposed to guide the forward end portions  20   b  of the ratchet members  20  to be engaged with the receiving portions  18   a  of the driving pulley  18 , and the swinging-prevention portions  25  are disposed to face the rearward end portions  20   c  of the ratchet members  20 . With this structure, the guide portions  24  and the swinging-prevention portions  25  can be placed close to each other in the circumferential direction, thereby reducing a free running distance of the rope reel  15 . The free running distance means a distance of movement from when a rotation of the rope reel  15  starts until when the ratchet members  20  are engaged with the driving pulley  18 . 
         [0055]    In this embodiment, the swinging-prevention portions  25  are disposed on the inner diameter side to contact the rearward end portions  20   c  of the ratchet members  20 . On the other hand, theoretically, the swinging-prevention portions  25  may be provided on the outer diameter side to contact the forward end portions  20   b  of the ratchet members  20 . In this case, the rib-like wall portions for forming the swinging-prevention portions  25  may protrude from an outer circumferential edge of the flange portion  23  of the ratchet guide  22 . 
         [0056]    However, if the swinging-prevention portions  25  are disposed on the outer diameter side, positions of the ratchet members  20  are moved to a further inner diameter side as compared with the case where the swinging-prevention portions  25  are disposed on the inner diameter side. As a result, a swinging amount required for causing the forward end portions  20   b  of the ratchet members  20  to protrude to the outer diameter direction to be engaged with the driving pulley  18  is increased. This results in a longer free running distance. 
         [0057]    In addition, if the rib-like wall portions protrude from the outer circumferential edge of the flange portion  23  of the ratchet guide  22 , the rib-like wall portions may be more easily deformed as compared with the case where the rib-like wall portions protrude from the inner diameter side of the flange portion  23 . Also, it may become difficult to continuously form the swinging-prevention portions  25  with the guide portions  24  to thereby strengthen them. 
         [0058]    According to this embodiment, the ratchet guide  22  includes the guide portions  24  that push out the ratchet members  20  to the outer diameter direction when the rope reel  15  rotates in the engine starting direction, and the swinging-prevention portions  25  that prevent the ratchet members  20  from swinging to the outer diameter direction when the ratchet members  20  do not contact the guide portions  24 . Thus, the ratchet members  20  can be pushed back reliably to the retracted position when the rope reel  15  rotates in the direction opposite to the engine starting direction. 
         [0059]    The ratchet guide  22  also functions as a retainer that retains the rope reel  15  with respect to the reel support shaft  12 . Thus, one member, that is the ratchet guide  22 , can have at least three functions of guiding the ratchet members  20  to be engaged with the driving pulley  18 , preventing the ratchet members  20  from unintentionally swinging, and retaining the rope reel  15 . Thus, many effects can be realized with a small parts count. 
         [0060]    The guide portions  24  are disposed to guide the forward end portions  20   b  of the ratchet members  20  to be engaged with the receiving portions  18   a  of the driving pulley  18 , and the swinging-prevention portions  25  are disposed to face the rearward end portions  20   c  of the ratchet members  20 . With this structure, even when the guide portions  24  and the swinging-prevention portions  25  are placed close to each other, the ratchet members  20  do not easily interfere with the swinging-prevention portions  25  when swinging to the outer diameter direction, and do not easily interfere with the guide portions  24  when swinging to the inner diameter direction. That is, the guide portions  24  and the swinging-prevention portions  25  can be placed closely with each other, and it is possible to reduce a free running distance until the ratchet members  20  are engaged with the driving pulley  18  from when the rope reel  15  is rotated to start the engine. 
         [0061]    The ratchet guide  22  includes a plurality (two, in this embodiment) of the guide portions  24  and a plurality (two, in this embodiment) of the swinging-prevention portions  25 , correspondingly with the number of the ratchet members  20 . That is, the ratchet guide  22  can be applied for a ratchet mechanism having any number of the ratchet members  20 . Thus, in the resulting recoil starter  10 , stable engagement with the driving pulley can be realized through the plurality of ratchet members  20 . 
         [0062]    Since the guide portions  24  and the swinging-prevention portions  25  are formed by the consecutive wall portions, it is also possible to strengthen the ratchet guide  22  by the consecutive wall portions.

Technology Category: 2