Patent Publication Number: US-6901900-B2

Title: Recoil starter for backpack type power working machine

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a recoil starter for an internal combustion engine, and in particular, to a recoil starter to be employed for starting an internal combustion engine which is adapted to be mounted on a backpack type power working machine such as a backpack type power brush cutter, a backpack type power sprayer, etc. 
   2. Description of the Related Art 
   The recoil starter to be employed for starting an internal combustion engine such as air-cooled two-stroke gasoline engine which is adapted to be mounted on a backpack type power working machine is generally constructed such that it is provided with a recoil handle (recoil rope) so that the internal combustion engine can be started by pulling the recoil handle against the compression-resisting force of the engine, and that once this recoil handle is released, the recoil rope is automatically wound up to the original state thereof by the effect of recoil-urging means. 
   When the recoil rope is kept wound up to the original state thereof, i.e. when the engine-starting operation is not performed, the recoil handle is usually kept stayed at the recoil rope outlet port of the main body of the starter. Therefore, it is difficult for the operator to reach the recoil handle under the condition where the working machine is kept shouldered by the operator&#39;s back, i.e. it is difficult for the operator to pull the recoil handle for starting the internal combustion engine under such a condition as mentioned above. 
   Therefore, if the operator wishes to restart the internal combustion engine after the engine is stopped while carrying the working machine on his back, the working machine is required to be dismounted from his back, causing significant inconvenience to the operator. 
   Whereas, when a D.C. motor type starter is employed as a starter, the internal combustion engine can be easily started while carrying the working machine on the operator&#39;s back. In that case however, the total weight of the working machine would be considerably increased due to the D.C. motor and the battery to be used as a power source for the D.C. motor, and the structure of the starter would become complicated, thus increasing the manufacturing cost thereof. 
   Under the circumstances, there has been proposed a recoil starter which enables an operator to perform the starting operation of the internal combustion engine under the condition where the backpack type power working machine is kept shouldered by the operator&#39;s back as disclosed in Japanese Utility Model Unexamined Publication (Kokai) S59-19975 wherein the recoil rope is designed to be guided by a flexible guide pipe up to the operator&#39;s shoulder portion. Since this recoil starter is constructed such that the recoil handle thereof (recoil rope and one end of the guide pipe) is not supported at all, it is difficult to smoothly perform the rope-pulling operation. Moreover, since the recoil rope and the guide pipe end are allowed to hang around during the working operation, they may disturb the working operation, thus raising a problem. 
   On the other hand, Japanese Utility Model Publication H2-48695 discloses a recoil starter wherein a proximal end portion of the guide pipe for guiding the recoil rope is supported by the main body of starter, and a distal end portion of the guide pipe is secured to the shoulder contact portion of the shouldering band. According to this recoil starter, since the recoil handle (grip) is supported at the vicinity of a front portion of the shoulder (or a distal end portion of the guide pipe), the recoil handle can be prevented from being hung up. However, there are problems that the face of the operator may be impinged against the recoil handle, thus hindering the movement of the operator, and that the recoil rope-pulling operation may become difficult. 
   Additionally, in the case of the conventional recoil starter according to the prior art, since the recoil handle is formed into such a configuration as to enable the recoil handle to be entirely grasped by fingers (i.e. clutch type configuration) in view of the attaching position and the pull-out direction of the recoil handle, it is unavoidable to cause a large magnitude of load to be imposed on the fingers on the occasion of pulling the recoil handle, and moreover, such a configuration is not necessarily convenient to grasp. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention has been made in view of overcoming the aforementioned problems accompanied with the conventional recoil starters, and therefore, it is an object of the present invention to provide a recoil starter for a backpack type power working machine, which is capable of easily performing the starting operation of an internal combustion engine under the condition where the working machine is kept shouldered by the operator&#39;s back, which can be manufactured lighter in weight and lower in manufacturing cost as compared with a D.C. motor type recoil starter, and the recoil handle of which is substantially free from hindering the movement of the operator and can be easily grasped by fingers, thereby enabling the recoil handle to be easily pulled out. 
   With a view to attaining the aforementioned object, there is provided, in accordance with the present invention, a recoil starter for starting an internal combustion engine to be mounted on a backpack type power working machine; which is characterized in that a recoil rope and a recoil handle attached to one end portion of the recoil rope are adapted to be pulled downward from a main body of the recoil starter; and that the recoil handle is provided with a lengthy grip portion whose length is larger than the width of the palm of the operator&#39;s hand. 
   In a preferable embodiment, both of the recoil rope and the recoil handle are disposed so as to be pulled down obliquely forward at an angle of 100° to 150° to the horizontal plane. 
   The recoil handle is preferably formed into a T-shaped configuration in side view, which comprises the aforementioned grip portion and a laterally extended stopper portion which is formed on a distal end, in the pull-out direction, of the grip portion. 
   In a preferable embodiment of the backpack type power working machine, the driving power source portion including an inner combustion engine is rotatably supported on a backpack frame so as to enable the driving power source portion to rotate about the vertical line; the main body of the starter is disposed on the right or left side of the driving power source portion; and a working means such as a driving shaft or a manipulating shaft which is provided at a distal end thereof with a cutting blade (in the case of a brush cutter), a spray tube (in the case of a power sprayer), etc. is disposed on the other side of the driving power source portion. 
   Further, the recoil starter is secured adjustably in position to the driving power source portion. 
   In a preferable embodiment of the recoil starter of the backpack type power working machine according to the present invention which is constructed as described above, since the recoil handle is disposed so as to be pulled down obliquely forward at an angle of 100° to 150° to the horizontal plane, the starting operation of the recoil starter can be easily performed with the working machine being kept shouldered by the operator&#39;s back. Moreover, according to the present invention, since only the mounting posture of the recoil starter and the recoil handle thereof are required to be modified with the main body of the recoil starter for a backpack type power working machine being permitted to be the same as the conventional recoil starter, it is possible to make the recoil starter lighter in weight and lower in manufacturing cost as compared with the D.C. motor type recoil starter. Further, since the recoil handle is positioned on the back of the operator, it is possible to prevent the recoil handle from hindering the movement of the operator during the operation of the power working machine. 
   Moreover, since the recoil handle is formed into a T-shaped configuration in side view, which comprises the grip portion having a length larger than the width of the palm of the operator&#39;s hand and a laterally extended stopper portion which is formed on a distal end, as viewed in the pullout direction, of the grip portion, it is possible to entirely grasp the recoil handle and to manipulate the recoil handle without imposing so much load on the grasping fingers as compared with the conventional clutch type recoil handle, thereby making it possible to easily perform the pulling operation of the recoil handle. 
   Further, since the recoil handle is made longer as compared with the conventional recoil handle, it is possible for an operator to easily reach the position of the recoil handle while shouldering the power working machine on his back. Additionally, since a laterally extended stopper portion is formed on the grip portion, it becomes possible to prevent the operator&#39;s hand from slipping out of the recoil handle, thereby enabling the pullout operation of the recoil handle (starting manipulation of the engine) and making it possible to minimize the failure of the starting manipulation of the engine. 
   Since the recoil starter for a backpack type power working machine according to the present invention is enabled to perform the starting operation of the engine with the working machine being kept shouldered by the operator&#39;s back, it is more preferable to design the recoil starter in such a manner as to enable the engine to be easily started even if the pulling force of the recoil rope is relatively small as compared with a recoil starter where the rope-pulling operation is performed after dismounting the working machine from the operator&#39;s back. 
   As for the recoil starter which enables the start-up of the engine to be performed with a relatively small magnitude of rope-pulling force, there is known a power-accumulating type recoil starter which has been previously proposed by the inventors. This power-accumulating type recoil starter comprises a driving member which can be rotated by the pulling of the recoil rope, a driven member to which the rotation of the driving member is designed to be transmitted, and a buffering/power-accumulating means which is disposed between the driving member and the driven member, wherein the buffering/power-accumulating means is enabled, during the driving process by the driving member, to accumulate the power supplied through the driving process while alleviating any shock to the driven member, the accumulated power being subsequently employed to drive the driven member (for more details, see Japanese Patent Unexamined Publication (Kokai) 2001-132591, which is incorporated herein by reference). 
   According to this power-accumulating type recoil starter, since the buffering/power-accumulating means (a spiral spring mechanism) is interposed between the driving member and the driven member, it is possible to derive a buffering effect from the spiral spring mechanism during the first-half driving process (until the piston of the internal combustion engine reaches the top dead center thereof) in the pulling operation of the recoil rope (recoiling operation), to enable the pulling force of the recoil rope to be accumulated in the spiral spring mechanism. During the latter-half driving process, the pulling force thus accumulated in the spiral spring mechanism during the first-half driving process is permitted to be combined with the pulling force to be actually effected in the latter-half pulling operation of the recoil rope to thereby generate a resultant force, which is utilized as a force for starting the internal combustion engine. As a result, it is possible to minimize a fluctuation in pulling force of rope so as to smooth the rope-pulling operation, and also to enable the engine to be easily started without necessitating a large magnitude of pulling force. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a perspective view of a recoil starter representing one embodiment of the present invention, which is shown together with a backpack type power working machine as they are viewed from the left front side thereof, 
       FIG. 2  is a partial sectioned left side view of the backpack type power working machine shown in  FIG. 1 ; and 
       FIG. 3  is a left side view of the power working machine for illustrating the pullout operation of the recoil handle of the starter shown in FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Next, one embodiment of the recoil starter according to the present invention will be explained with reference to the drawings. 
     FIG. 1  is a perspective view of a recoil starter representing one embodiment of the present invention, which is shown together with a backpack type power brush cutter as one example of a backpack type power working machine as they are viewed from the left front side thereof, and  FIG. 2  is a left side view of the backpack type power brush cutter including the recoil starter both shown in FIG.  1 . 
   Referring to  FIGS. 1 and 2 , this backpack type power brush cutter  10  comprises an L-shaped (in side view) backpack frame  12  having a pair of shouldering bands  14 A, a back-resting pad  13  secured to the vertical frame portions  12 A of the shouldering frame  12 , and a driving power source portion  15  mounted, through a mounting member  14  acting also as a vibration damping and absorbing member, on the bottom frame portions  12 B of the backpack frame  12 , this driving power source portion  15  being mainly constituted by an air-cooled two-stroke gasoline engine (internal combustion engine)  17  functioning as the driving power source and by a fuel tank  18 . 
   This driving power source portion  15  is rotatably supported by means of a pivot  16  which is secured to the mounting member  14  so that the driving power source portion  15  is able to rotate about the vertical line G—G in the horizontal plane. A main starter body  20 A of the recoil starter  20  according to this embodiment is disposed on the right or left side (in this case, on the left side) of the driving power source portion  15 , and a flexible drive shaft built-in tube  40  is disposed as working means on the other side (in this case, on the right side). This flexible drive shaft built-in tube  40  is coupled with a manipulating rod which is provided at a distal end thereof with a working member such as brush cutter (not shown). Therefore, if the driving power source portion  15  is rotated by 180°, the recoil starter  20  can be disposed on the right side of the driving power source portion  15 , while the flexible drive shaft built-in tube  40  acting as working means can be disposed on the left side of the driving power source portion  15 . 
   This recoil starter  20  is of a power-accumulating type. It comprises a driving member including a rope reel around which a recoil rope  25  is wound and which is enabled to be rotated as the recoil rope  25  (recoil handle  30 ) is pulled out, and a spiral spring functioning as recoil-urging means for reversely rotating the rope reel so as to automatically wind up the recoil rope  25 . This recoil starter  20  also comprises a driven member to which the rotation of the aforementioned driving member is transmitted, and a spiral spring mechanism functioning as buffering/power-accumulating means, which is disposed between the driving member and the driven member, wherein the buffering/power-accumulating means is enabled, during the driving process by the driving member, to accumulate the power supplied through the driving process by the driving member while alleviating any shock to the driven member, the accumulated power being subsequently utilized to drive the driven member. 
   The main starter body  20 A of the recoil starter  20  is provided with a rope outlet port  23  which is extended obliquely forward from a lower portion the recoil starter  20 , thereby directing the rope outlet port  23  toward the operator&#39;s back side. As a result, the recoil rope  25  and the recoil handle  30  attached to the distal end of the recoil rope  25  are enabled to be pulled down obliquely toward the operator (see the state of the recoil rope  25  shown in FIG.  3 ). 
   More specifically, as shown in  FIG. 3 , the recoil handle  30  is formed into a T-shaped configuration in side view, which is constituted by a grip portion  31  which has a length (a length Lg) larger than the width Lp of the palm P of the operator&#39;s hand (for example, about twice the width of the palm of the operator&#39;s hand) and is linearly extended along the pull-out direction F of the recoil rope  25 , and a laterally extended stopper portion (for example, shaped into a circular flange)  32  which is formed on a distal end, in the pull-out direction, F, of the grip portion  31 . The recoil rope  25  and the recoil handle  30  are adapted to be pulled down obliquely toward the operator at an angle α (about 120° in this embodiment) to the horizontal plane K. 
   The grip portion  31  may be of any optional configuration, such as a rod of circular cross-section having a diameter which can be easily grasped with the operator&#39;s hand. 
   In the recoil starter  20  for a backpack type power working machine, which is constructed according to this embodiment, the start-up of the internal combustion engine  17  can be performed as follows. Namely, as shown by an imaginary line in  FIG. 3 , under the condition where the backpack type power working machine  10  is kept shouldered by an operator M, the grip portion  31  of the recoil handle  30  is grasped with the palm P of the operator&#39;s hand by slightly bending his left arm H for example, and then, the grip portion  31  is pulled down obliquely toward the operator (at an angle of about 120° to the horizontal plane K). After the recoil handle  30  has been pulled out in this manner, the grip portion  31  of the recoil handle  30  is permitted to be released from the palm P of the operator&#39;s hand. As a result, due to the effect of the recoil-urging means which is built in the main starter body  20 A, the recoil handle  30  is automatically brought back to the original position thereof (the state where the recoil handle  30  is impinged against the rope outlet port  23 ). 
   Since the recoil handle  30  and the recoil rope  25  are constructed in this manner so as to be pulled down obliquely forward, the starting operation of the recoil starter can be easily performed with the working machine  10  being kept shouldered by the operator&#39;s back. Moreover, according to the present invention, since only the mounting posture of the recoil starter  20  and the recoil handle thereof are required to be modified with the main starter body  20 A of the recoil starter  20  for a backpack type power working machine being permitted to be the same as the conventional recoil starter, it is possible to make the recoil starter  20  lighter in weight and lower in manufacturing cost as compared with the D.C. motor type recoil starter. Further, since the recoil handle  30  is positioned on the back of the operator, it is possible to prevent the recoil handle from hindering the movement of the operator M during the operation of the power working machine. 
   Additionally, since the recoil handle  30  is formed into a T-shaped configuration in side view, which is constituted by the linear grip portion  31  having a length larger than the width Lp of the palm P of the operator&#39;s hand, and a laterally extended stopper portion  32  which is formed on a distal end, as viewed in the pulling direction, of the grip portion  31 , it is possible to entirely grasp the grip portion  31  of the recoil handle  30  and to manipulate the recoil handle  30  without imposing so much load on the grasping fingers as compared with the conventional clutch type recoil handle, thereby making it possible to easily perform the pulling operation of the recoil handle. 
   Further, since the recoil handle  30  is made longer as compared with the conventional recoil handle so as to dispose it in front of the working machine, it is possible for the operator M to easily reach the position of the recoil handle while shouldering the power working machine on his back. Additionally, since the laterally extended stopper portion  32  is formed on the grip portion  31 , it becomes possible to prevent the operator&#39;s hand from slipping out of the recoil handle  30 , thereby enabling the pullout operation of the recoil handle  30  (starting manipulation of the engine) and making it possible to minimize the failure of the starting manipulation of the engine. 
   Moreover, the recoil handle  30  can be manipulated in such a manner that the laterally extended stopper portion  32  is grasped with the grip portion  31  being held between the forefinger and middle finger of the operator&#39;s hand. 
   If it is desired that the recoil starter  20  is disposed on the opposite side of the backpack type power working machine  10  by rotating the driving power source portion  15  by an angle of 180°, the fixing means such as screws which anchor the main starter portion  20 A of the recoil starter  20  to the internal combustion engine  17  are loosened so to permit the position of the driving power source portion  15  to be moved and adjusted (for example, by rotating the driving power source portion  15 ). Then, the angle α of the pull-out direction F of the recoil handle  30  is downwardly inclined toward the front side of the working machine  10  by an angle ranging from 100° to 150° to the horizontal plane and fixed at that position, thereby enabling the recoil handle  30  to be suitably manipulated even on the opposite side of the backpack type power working machine  10 . 
   While in the foregoing, one embodiment of the present invention has been explained, it will be understood that the present invention is not limited to the embodiment, but the construction thereof can be varied without departing from the spirit and scope of the invention. 
   As clearly understood from the above explanation, the starting operation of the recoil starter for a backpack type power working machine according to the present invention can be easily performed with the working machine being kept shouldered by the operator&#39;s back. Moreover, since only the mounting posture of the recoil starter and the recoil handle thereof are required to be modified with the other components being permitted to be the same as the conventional recoil starter for a backpack type power working machine, it is possible to make the recoil starter lighter in weight and lower in manufacturing cost as compared with the D.C. motor type recoil starter. Further, since the recoil handle is positioned on the back side of the operator on the occasion of operating the power working machine, it is possible to prevent the recoil handle from hindering the movement of the operator during the operation of the power working machine. 
   Moreover, since the recoil handle is formed into a T-shaped configuration in side view, which is constituted by the grip portion having a length larger than the width of the palm of the operator&#39;s hand and a laterally extended stopper portion which is formed on a distal end, as viewed in the pulling direction, of the grip portion, it is possible to entirely grasp the recoil handle and to manipulate the recoil handle without imposing so much load on the grasping fingers as compared with the conventional clutch type recoil handle, thereby making it possible to easily perform the pulling operation of the recoil handle. 
   Further, since the recoil handle is made longer as compared with the conventional recoil handle, it is possible for an operator to easily reach the position of the recoil handle while shouldering the power working machine on his back. Additionally, since a laterally extended stopper portion is formed on the grip portion, it becomes possible to prevent the operator&#39;s hand from slipping out of the recoil handle, thereby enabling the pullout operation of the recoil handle (starting manipulation of engine) and making it possible to minimize the failure of the starting manipulation of engine.