Abstract:
A power-storage-type engine starting system includes a coil spring for storing power to be used in starting the engine. An end of a crankshaft is configured to pass through a cylindrical shaft part and is passed through a one-way clutch attached to inside of an assist boss so that an assist boss and the one-way clutch can be provided at radially outside of the shaft end, whereby the crankshaft is made shorter.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an improvement in a power-storage-type engine starting system that utilizes power stored in a spring to start a multi-purpose engine. 
     BACKGROUND OF THE INVENTION 
     Japanese Patent Application Laid-Open Publication No. 2004-263615 discloses a power-storage-type recoil starter. In the disclosed recoil starter, a reel support shaft attached to the fixed side of an engine via a main body casing is provided on the extension axis of a crankshaft, and a recoil pulley on which a recoil rope is wrapped is rotatably attached to the reel support shaft. 
     In the power-storage-type recoil starter described above, the main body casing is attached to the engine. The reel support shaft is attached to the center part of the main body casing so as to be positioned on the extension axis of the crankshaft. A rope reel is rotatably attached to the reel support shaft. The recoil rope is wrapped onto the rope reel. A handle is attached to the end of the recoil rope. 
     The rope reel is connected to a spring case via a speed reduction mechanism, and a cam wheel is connected to the spring case via a power storage mechanism. A rotating member is connected to the cam wheel via a transmission mechanism. The rotating member is attached to the crankshaft. 
     The transmission mechanism is provided between the cam wheel and the rotating member so that the rotation of the engine when the engine starts is not transmitted to the recoil starter. The transmission mechanism is composed of a plurality of cam claws formed on the external peripheral surface of the cam wheel, and a centrifugal ratchet provided to the rotating member so as to be engaged with the cam claws by centrifugal force. 
     However, in the conventional recoil starter, the centrifugal ratchet that constitutes the transmission mechanism is structured so as to separate from the cam claws by centrifugal force, and since the centrifugal ratchet is necessarily provided at the crankshaft and to the outside in the radial direction of the cam claws, a cylindrical rotating member must be attached to the crankshaft, and the cam wheel must be rotatably supported by the reel support shaft. Specifically, a pulley support shaft must be provided on the extension axis of the crankshaft, and the profile of an engine that includes the recoil starter is enlarged in the direction of the crankshaft. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to reduce the size of an engine that is provided with a power-storage-type recoil starter. 
     According to the present invention, there is provided a power-storage-type engine starting system which comprises: a power-storage-type recoil starter; a crankshaft rotatable by the recoil starter to start the engine; a recoil pulley rotatably supported by a pulley support shaft and having a recoil rope wrapped therearound; a wheel member adapted to be rotatably supported by the crankshaft of the engine; and a power storage mechanism for storing power by pulling the recoil rope and rotating the recoil pulley, the power storage mechanism being provided between the recoil pulley and the wheel member, wherein the crankshaft has an end passing through the pulley support shaft and inserted into a one-way clutch which is attached to inside of the wheel member. 
     When the engine starts, rotation of the crankshaft is not transmitted to the wheel member by the one-way clutch. Consequently, there is no need for a structure in which a centrifugal ratchet and cam claws engage with each other, as in the conventional technique; there is no need for a structure such as that of the conventional technique in which a cylindrical rotating member is attached to the end of the crankshaft, and a reel support shaft such as in the conventional technique is provided on the extension axis of the crankshaft; and the dimensions of the power-storage-type recoil starter in the axial direction of the crankshaft can be reduced. Consequently, the size of the engine started by the power-storage-type recoil starter can be reduced. 
     Preferably, the power storage mechanism comprises a coil spring in which a number of turns between the recoil pulley and the wheel member gradually increases and power is stored by pulling of the recoil rope. 
     Desirably, the wheel member comprises a boss body through which the shaft end of the crankshaft passes, and the boss body has a front spring chamber for accommodating the power storage mechanism, the power storage mechanism being formed between the recoil pulley and a rear boss provided to a rear part of the boss body. 
     In a preferred form, the one-way clutch meshes with the crankshaft when power is transmitted from the power storage mechanism to the crankshaft, and the wheel member and the crankshaft thereby rotate integrally with each other via the one-way clutch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a front elevational view showing an engine provided with a power-storage-type recoil starter according to the present invention; 
         FIG. 2  is a view of the engine as seen in the direction of arrow  2  of  FIG. 1 ; 
         FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 1 ; 
         FIGS. 4A and 4B  are sectional views showing the structure and operation of a one-way clutch; 
         FIGS. 5A and 5B  are sectional views showing the power-storage-type recoil starter in a state in which the engine has not been started; 
         FIGS. 6A and 6B  are sectional views showing an operation of the power-storage-type recoil starter in a state in which a recoil rope has been pulled and power is stored; 
         FIGS. 7A and 7B  are sectional views showing an operation of the power-storage-type recoil starter, with a crankshaft rotating from the power-stored state shown in  FIG. 6B ; and 
         FIG. 8  is a sectional view showing an example of the recoil starter of the present invention being used in an engine generator. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An engine  10  shown in  FIG. 1  is provided with a crankcase  11 ; a cylinder block  12  attached to the crankcase  11  so as to extend at an angle upward and to the side; a cylinder head  13  attached to an end of the cylinder block  12 ; a muffler  16  attached to the front of the cylinder head  13  via an exhaust pipe  14 ; a carburetor (not shown) attached to the rear of the cylinder head  13 ; an air cleaner  17  connected to the carburetor; a fuel tank  18  attached to the top of the crankcase  11  to feed fuel to the carburetor; and a starter cover  21  attached to the front of the crankcase  11  in order to cover a power-storage-type recoil starter  40  ( FIG. 2 ). 
     The reference numeral  23  refers to a head cover for covering an end opening of the cylinder head  13 , and the reference numeral  24  refers to a starter handle (grip) that is provided to the power-storage-type recoil starter  40 . 
     As shown in  FIG. 2 , a crankshaft  31  that extends to the front and rear is rotatably attached to the crankcase  11  of the engine  10 . The power-storage-type recoil starter  40  covered by the starter cover  21  is provided to a front end of the crankshaft  31 . 
     The reference numeral  33  refers to an exhaust port of the muffler  16 . The air cleaner  17  has an air cleaner cover  34 . 
     As shown in  FIG. 3 , the power-storage-type recoil starter  40  is composed of a fixed plate  42  attached to a front surface  11   a  of the crankcase  11  by a plurality of screws  41 ; a recoil pulley  43  rotatably attached to a cylindrical shaft part (pulley support shaft)  42   a  provided in the center of the fixed plate  42 ; a recoil rope  44  wrapped onto the recoil pulley  43 ; a starter handle  24  ( FIG. 1 ) attached to an end of the recoil rope  44 ; a returning spring  46  provided between the fixed plate  42  and the recoil pulley  43 ; an assist boss (wheel member)  47  provided adjacent to and in front of the recoil pulley  43 ; an assist spring (power storage mechanism)  48  provided between the recoil pulley  43  and the assist boss  47 ; a one-way clutch  51  pressed into the inside of the assist boss  47  and fitted on a shaft end  31   a  of the crankshaft  31  so as to be able to rotate in one direction; a washer  52  for preventing the one-way clutch  51  from coming off the shaft end  31   a ; and a bolt  53  for attaching the washer  52  to the shaft end  31   a.    
     The reference numeral  54  refers to a bearing for rotatably supporting the crankshaft  31 , and the reference numeral  55  refers to a seal member. 
     The one-way clutch  51  is provided between the assist boss  47  and the shaft end  31   a  of the crankshaft  31 ; i.e., the shaft end  31   a  of the crankshaft  31  is configured to pass through the one-way clutch  51 . 
     The fixed plate  42  is composed of a plate-shaped part  42   b , a plurality of attachment bosses  42   d  formed on a back surface  42   c  of the plate-shaped part  42   b  so as to protrude to the rear, an annular concave part  42   e  formed in the center of the plate-shaped part  42   b , and a cylindrical shaft part  42   a  formed on an internal wall of the annular concave part  42   e.    
     The starter cover  21  is attached to the external periphery of the fixed plate  42 . 
     The attachment bosses  42   d  are attached by the screws  41  to crankcase bosses  11   b  formed on the front surface  11   a  of the crankcase  11 . 
     A pulley boss  43   a  formed integrally with the rear part of the recoil pulley  43  is inserted into the annular concave part  42   e . The cylindrical shaft part  42   a  rotatably supports the pulley boss  43   a  of the recoil pulley  43 . A gap is formed between an external peripheral surface  42   f  of the cylindrical shaft part  42   a  and the shaft end  31   a  of the crankshaft  31 . 
     The recoil pulley  43  is composed of a pulley main body  43   b , the pulley boss  43   a  formed at the rear of the pulley main body  43   b , and a front cylinder part  43   c  formed at the front of the pulley main body  43   b.    
     A rear spring chamber  56  for accommodating the returning spring  46  is formed between the cylindrical shaft part  42   a  of the fixed plate  42  and a rear cylinder part  43   d  formed at an end of the pulley boss  43   a . One end each of the returning spring  46  is attached to the rear cylinder part  43   d  and the cylindrical shaft part  42   a . A rope groove  43   e  is formed along the entire external periphery of the pulley main body  43   b . The recoil rope  44  is wrapped into the rope groove  43   e.    
     When the recoil rope  44  is pulled and the recoil pulley  43  is rotated about the cylindrical shaft part  42   a  of the fixed plate  42 , the number of turns of the returning spring  46  gradually increases, and power is stored therein. When pulling of the recoil rope  44  is stopped and the recoil rope  44  is relaxed, the recoil pulley  43  is rotated in reverse by the stored power, and the recoil pulley  43  returns to the original position. 
     The assist boss  47  is composed of a boss body  47   a  through which the shaft end  31   a  of the crankshaft  31  passes, and a flange part  47   b  that extends in the radial direction from an external peripheral surface of the boss body  47   a.    
     A rear boss  47   c  is provided at the rear of the boss body  47   a , a front spring chamber  58  for accommodating the assist spring  48  is formed between the rear boss  47   c  and the front cylinder part  43   c  of the recoil pulley  43 , and one end each of the assist spring  48  is attached to the rear boss  47   c  and the front cylinder part  43   c.    
     A large-diameter hole  47   d  into which the one-way clutch  51  is pressed is formed on the internal peripheral surface of the boss body  47   a . A gap is formed between an internal peripheral surface  47   e  of the rear boss  47   c  and the shaft end  31   a  of the crankshaft  31 . 
     The assist spring  48  is a coil spring in which the number of turns between the recoil pulley  43  and the assist boss  47  gradually increases and power is stored when the recoil rope  44  is pulled and the recoil pulley  43  is rotated about the cylindrical shaft part  42   a  of the fixed plate  42 . When pulling of the recoil rope  44  is stopped, and the state of pulling is maintained after power is stored in the assist spring  48 , the stored power is transmitted to the crankshaft  31  via the assist boss  47  and the one-way clutch  51 , the crankshaft  31  is rotated, and the engine starts. 
     When power is transmitted to the crankshaft  31  from the assist spring  48 , the one-way clutch  51  is in a meshed state, and the assist boss  47  and the crankshaft  31  rotate in integral fashion via the one-way clutch  51 . 
       FIGS. 4A and 4B  show the structure and operation of the one-way clutch. 
     A shown in  FIG. 4A , the one-way clutch  51  is composed of an outer wheel  61 , a retainer  62  rotatably attached to the inside of the outer wheel  61 , and a plurality of rollers  63  retained by the retainer  62 . 
     Depressions  61   a  are formed in the internal peripheral surface of the outer wheel  61  so as to correspond to the rollers  63 , and cam surfaces  61   b  formed so as to gradually approach the shaft end  31   a  of the crankshaft  31  are formed in the depressions  61   a.    
     The retainer  62  is provided with elastic members  64  for retaining the rollers  63  in the circumferential direction of the one-way clutch  51 . 
     In the drawings, the rollers  63  are kept in a free state in the depressions  61   a  of the outer wheel  61 . The outer wheel  61  rotates in the direction of the arrow with respect to the shaft end  31   a  of the crankshaft  31 . 
     In  FIG. 4B , when the outer wheel  61  is rotated in the direction of the arrow with respect to the shaft end  31   a  of the crankshaft  31 , the rollers  63  move into the wedge-shaped spaces formed by the shaft end  31   a  and the cam surfaces  61   b  of the outer wheel  61 , and the one-way clutch  51  is brought to a meshed state. The shaft end  31   a  therefore rotates together with the outer wheel  61  via the plurality of rollers  63 , and the outer wheel  61  and the shaft end  31   a  do not rotate relative to each other. 
     An operation of the power-storage-type recoil starter  40  described above will next be described. 
       FIGS. 5A and 5B  show the operation of the recoil starter when the recoil rope is not pulled, and when the recoil rope is slightly pulled when the engine is stopped. 
       FIG. 5A  shows a state when the engine is stopped. 
     The starter handle  24  is attached to one end of the recoil rope  44 , and the other end of the recoil rope  44  is attached to an external peripheral part of the recoil pulley  43 . 
     One end of the assist spring  48  is attached to an internal peripheral part of the recoil pulley  43 , and the other end of the assist spring  48  is attached to an external peripheral part of the assist boss  47 . The outer wheel  61  of the one-way clutch  51  is pressed in on the internal peripheral surface of the assist boss  47 , and the plurality of rollers  63  of the one-way clutch  51  is arranged so as to be able to touch the external peripheral surface of the shaft end  31   a  of the crankshaft  31 . 
     In the structure described above, the rotational force transmitted to the recoil pulley  43  via the recoil rope  44  by the pulling of the starter handle  24  acts on the assist spring  48  so as to increase the number of turns thereof and store power, and the rotational force is furthermore transmitted to the assist boss  47 . The assist boss  47  is thereby rotated, causing the one-way clutch  51  to rotate so as to mesh with the crankshaft  31  and to cause the crankshaft  31  to rotate. 
     A piston connected to the crankshaft  31  of the engine via a connecting rod is positioned at the bottom dead center (BDC) of the engine expansion (EXP) stroke, for example, as indicated by a black circle in the piston position display chart shown in the drawing, and the crankshaft is stopped in a rotation position that corresponds to this piston position. The white arrow in the drawing indicates the rotation position of the crankshaft  31  (the white arrow points downward, indicating that the piston is positioned at the bottom dead center). In the piston position display chart, reference character EXP indicates an expansion stroke; EXH an exhaust stroke; INT an intake stroke; and COM a compression stroke, 
     The black circle  71  on the recoil pulley  43 , and the black triangle  72  on the assist boss  47  in the drawing indicate the target rotation positions of the recoil pulley  43  and the assist boss  47 , respectively. 
     Beginning in the state shown in  FIG. 5A , when the recoil rope  44  is pulled as indicated by the arrow A by the starter handle  24  as shown in  FIG. 5B , the recoil pulley  43 , the assist spring  48 , the assist boss  47 , and the outer wheel  61  of the one-way clutch  51  rotate substantially integrally as indicated by the arrows B and C. As a result, the plurality of rollers  63  of the one-way clutch  51  is placed between the shaft end  31   a  of the crankshaft  31  and the cam surfaces  61   b  of the outer wheel  61 , the outer wheel  61  of the one-way clutch  51  is meshed with the shaft end  31   a , and the outer wheel  61  and shaft end  31   a  are able to rotate integrally with each other. 
       FIGS. 6A and 6B  show a state in which the recoil rope is further pulled from the state shown in  FIG. 5B . 
     Beginning in the state shown in  FIG. 5B , the recoil rope  44  is further pulled in the direction of the arrow D as shown in  FIG. 6A , and the crankshaft  31  is rotated as indicated by the arrow E until the piston reaches the initial position of the compression stroke. 
     Rotation range of the crankshaft  31  at this time is the run-up zone of the rotation of the crankshaft  31 . The recoil pulley  43 , the assist spring  48 , the assist boss  47 , the one-way clutch  51 , and the crankshaft  31  rotate substantially integrally, and there is almost no twisting of the assist spring  48 . 
     In this rotation position of the crankshaft  31 , since the compression pressure inside the combustion chamber increases, a response is suddenly felt when the recoil rope  44  is pulled by the starter handle  24 , and a large pulling force is required. 
     Beginning in the state shown in  FIG. 6A , when the recoil rope  44  is further pulled by the starter handle  24  as indicated by the arrow F in  FIG. 6B , since the rotation of the crankshaft  31  is almost completely stopped by the abovementioned high pressure in the combustion chamber, there is also almost no rotation of the one-way clutch  51  and the assist boss  47 , and the assist spring  48  is therefore twisted by the rotation of the recoil pulley  43  such as indicated by the arrow G so that the number of turns of the assist spring  48  increases, and power is stored in the assist spring  48 . 
       FIGS. 7A and 7B  show the state in which the crankshaft  31  is rotated by the rotational force stored by the assist spring  48 . 
     When the rotational force stored by the assist spring  48  in the state shown in  FIG. 6B  reaches a predetermined rotational force, the assist boss  47 , the one-way clutch  51 , and the shaft end  31   a  of the crankshaft  31  are assisted by the rotational force so as to rotate integrally as indicated by the arrow H in  FIG. 7A , and the piston moves past the top dead center of the compression stroke to the expansion stroke. Combustion of the mixture begins at this time in the combustion chamber of the engine, and the engine starts. 
     When the crankshaft  31  in the state shown in  FIG. 7A  begins to rotate as indicated by the arrow J under its own power as shown in  FIG. 7B , the rollers  63  separate from the cam surfaces  61   b  of the outer wheel  61  of the one-way clutch  51 ; a state occurs in which the outer wheel  61 , the assist boss  47 , the assist spring  48 , and the recoil pulley  43  are separated from the shaft end  31   a  of the crankshaft  31 ; and rotation stops. When pulling of the recoil rope  44  is also relaxed, the outer wheel  61 , the assist boss  47 , the assist spring  48 , and the recoil pulley  43  are also returned to the original positions thereof (positions shown in  FIG. 5A ) by the returning spring  46  (see  FIG. 3 ). 
       FIG. 8  shows an example in which the power-storage-type recoil starter  40  of the present embodiment is applied to an engine generator. 
     As shown in  FIG. 8 , a cover member  75  is attached to the fixed plate  42  so as to cover the power-storage-type recoil starter  40 , a flywheel  77  is attached to the distal end of the shaft end  31   a  of the crankshaft  31  via an extended tapered shaft  76 , and a generator  78  is attached to the cover member  75  and flywheel  77 . 
     The generator  78  is composed of a stator  82  attached to the cover member  75  by a plurality of bolts  81 ; and a rotor (not shown) attached to the flywheel  77  so as to rotate near the periphery of the stator  82 . 
     The stator  82  is composed of a stator core  84  and a stator coil  85  that is wrapped onto the stator core  84 . 
     As shown in  FIGS. 3 ,  5 A, and  5 B above, the power-storage-type recoil starter  40  is provided with the recoil pulley  43  rotatably supported by the cylindrical shaft part  42   a  as a pulley support shaft, the recoil rope  44  being wrapped onto the recoil pulley  43 ; the assist boss  47  as a wheel member rotatably supported on the crankshaft  31  of the engine  10  ( FIG. 1 ); and the assist spring  48  as a power storage mechanism that is provided between the recoil pulley  43  and the assist boss  47 . In the power-storage-type recoil starter  40 , the recoil rope  44  is pulled to rotate the recoil pulley  43 , whereby power is stored in the assist spring  48 , and the power is transmitted from the assist spring  48  to the crankshaft  31  via the assist boss  47 , thereby starting the engine  10 . The shaft end  31   a  of the crankshaft  31  is configured to pass through the cylindrical shaft part  42   a , and the shaft end  31   a  of the crankshaft  31  is inserted into the one-way clutch  51  that is attached to the inside of the assist boss  47 . The assist boss  47 , the one-way clutch  51 , and the crankshaft  31  can therefore be arranged in the radial direction, and the dimensions of the power-storage-type recoil starter  40  can be reduced in the axial direction of the crankshaft. Consequently, the engine  10  that includes the power-storage-type recoil starter  40  can be reduced in size. 
     The one-way clutch  51  was positioned further forward than the assist spring  48  in the present embodiment, as shown in  FIG. 3 , but this configuration is not limiting, and the one-way clutch  51  may also be provided on the inside in the radial direction of the assist spring  48 . The dimensions of the crankshaft  31  in the front and rear, i.e., the length of the crankshaft  31 , can thereby be reduced, and the engine  10  that includes the power-storage-type recoil starter  40  ( FIG. 1 ) can be reduced in size. 
     Obviously, various minor changes and modifications of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.