Patent Publication Number: US-7594490-B2

Title: Engine starter

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/199,297, filed Aug. 8, 2005, which claims the benefit of Japanese Patent Application No. 2004-232139, filed Aug. 9, 2004, and Japanese Patent Application No. 2004-232140, filed Aug. 9, 2004, all of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an engine starter which starts an internal combustion engine by using an ultra-compact direct current motor, and more particularly to an electric engine starter which can remove a conventional recoil driving unit from its body and arrange a battery for driving the motor, outside there, hence to realize downsizing because of the most efficient arrangement of the components and to extremely decrease fatigues at each operation of various working machine. 
     2. Description of the Related Art 
     At the present, an engine starter which starts a compact air-cooled gasoline engine mounted on a popular portable machine such as a shearing machine and a chain saw generally includes a recoil driving unit, a follower connected to a crank shaft of an engine through an switching means such as a centrifugal clutch, and a shock absorbing/pressure accumulating unit including a spring, arranged between the driving unit and the follower for absorbing the driving power of the driving unit and accumulating the pressure under the follower. The recoil driving unit has a recoiling reel with a recoil rope wound there and a recoiling spring arranged between the recoiling reel and a casing, the internal and external ends of the recoiling spring being respectively fixed to the recoiling reel and the casing. The recoiling reel is rotated only in one direction by drawing the recoil rope, the recoiling spring is wound up to accumulate a spring power, and when the recoil rope is released in this state, the accumulated power of the recoiling spring is released to wind back the recoiling reel automatically. 
     The above recoil driving unit requires a drawing operation for drawing the recoil rope every time of starting the engine. The drawing operation of the recoil rope has to be done so quickly and widely that a person having little power or an elderly person cannot start the engine only by one drawing operation. Thus, there have been a lot of proposals to make the engine start easy through the drawing operation of the recoil rope and they are in a practical use, but the troublesome operation of the drawing operation itself still remains. On the other hand, a progress in the recent compact electric motor and battery is remarkable and in spite of being downsized, they come to have the larger capacity. Taking this situation into account, an electric engine starter is reviewed which can start an engine quickly and easily by a switching operation, in order to avoid the troublesome operationality of the above recoiling starter, and its development is desired. 
     A compact electric engine starter of this kind includes the engine starter of old disclosed in, for example, Japanese Utility Model Application Laid-Open (JP-U) No. 63-110672 (patent document 1). This starter includes a direct current motor which is driven by the power of a battery, a spring which is wound up through the operation of a spring barrel drum by a warm gear fixed to an output shaft of the motor, an output rotation shaft to which the lateral end of the spring is fixed, a rotation shaft of the engine connected to the output rotation shaft through a one-direction clutch, a rotation lever which stops the rotation of the output rotation shaft or releases the stop, an interlock electric switch which operates to turn on only at a stage of releasing the rotation stop of the output rotation shaft by the lever, and an armature current controller which drives the motor at a time of turning off the electric switch, winds up the spring while keeping the rotation also when the rotation speed of the motor is beyond the set rotation speed, and stops the rotation of the motor by the power off when the rotation speed falls down below the set rotation speed at a time of finishing the winding up of the spring. A speed reducing gear may be interposed between the warm gear and a gear formed around the outer periphery of the spring barrel drum. 
     By way of example, Japanese Patent No. 2573340 (patent document 2) discloses a spring-driven starter which accommodates into a single frame a battery, a direct current electric motor driven by the electric power of the battery, a controller which controls the stop of the operation of the motor, a reduction gear mechanism of high reduction gear ratio which transmits the power of the motor, a spring-driven power accumulating unit or which is driven by the reduction gear mechanism, and a driving power transmitter which transmits the power of the accumulating unit to the crank shaft one-sidedly. The reduction gear mechanism of high reduction gear ratio includes a planetary reduction gear of the first stage to be driven by the direct current electric motor, which is arranged on the other axis line parallel to the crank shaft, and a reduction gear of the second stage which is formed by meshing a driven gear integrated with the outer periphery of the spring power accumulating room of the accumulating unit, with a driving gear provided on the output shaft of the planetary reduction gear. 
     For example, in JP-U No. 2-13171, a spring barrel drum is pivoted rotatably in one direction through a supporting system of the planetary reduction gear arranged at the opposite side of the crankshaft of the engine. The rotation speed of the spring barrel drum is reduced by the planetary reduction gear connected through a pair of reduction spur gears composed of a small gear and a large gear fixed to the output shaft of the direct current electric motor arranged within the housing. One-way rotation at this time is performed by the mesh of a ratchet claw and a tooth portion provided on the outer peripheral portion of the spring barrel drum. A start ratchet wheel and a start ratchet claw are arranged on the side of the crankshaft of the spring barrel drum and when the mesh is released, the ratchet wheel becomes rotatable. A starter ratchet wheel is built in the start ratchet wheel and the starter ratchet wheel is engaged in a centrifugal clutch claw provided in the crankshaft. 
     The ratchet wheel is integrated with the outer periphery of the spring barrel drum and the ratchet wheel of small diameter is engaged in the upper end portion of the spring barrel drum. A rotation shaft fixed to the ratchet wheel of small diameter is designed to remove a manual crank externally. During the ordinal operation of the engine, the manual crank is not inserted and the ratchet wheel of small diameter runs idle. When failing in start and trying to rewind the spring, the manual crank is inserted into the rotation shaft of the ratchet wheel of small diameter, to rotate the spring barrel drum and accumulate the pressure in the spring. At an engine start time, the above start ratchet is operated, an energy accumulated in the spring is released to rotate the starter ratchet wheel, thereby to crank and start the engine. 
     A starter, for example, in Japanese Patent Application Laid-Open (JP-A) No. 2002-285940 interposes a shock absorbing/pressure accumulating means on the way of the power transmission system between a driving unit and a follower. The driving unit is an electric motor as its driving source and a reduction mechanism is formed by a warm jointly fixed to the output rotation shaft of the electric motor and a warm wheel provided on the outer periphery of the spring barrel drum. The above structure is actually the same as that of the above JP-U No. 63-110672. A recoil driving unit is provided on the driving side, separately from the electric motor, and the recoil driving unit includes a rope reel with a recoil rope wound there, which reel is rotated by drawing the recoil rope, a recoiling spring which rotates the rope reel inversely so as to wind up the recoil rope, and a recoiling ratchet mechanism which transmits the rotation of the rope reel to the shock absorbing/pressure accumulating means. The spring barrel drum is designed to rotate only in one direction by a one-way clutch. Owing to this structure, the starter of the JP-A No. 2002-285940 may be referred to as only the combination of the above JP-U No. 63-110672 and the well-known recoil mechanism. 
     According to the engine starter of the above JP-U No. 63-110672, since the warm gear directly connected to the electric motor is engaged in the warm wheel formed on the outer periphery of the spring barrel drum, hence to rotate the spring barrel drum in one direction, the spring barrel drum is not rotated inversely, but in this power transmission mechanism due to the engagement of the warm gear and the warm wheel, the output axis direction of the electric motor and the rotation driving shaft of the spring barrel drum cross at right angle, and thus for the sake of design, efficiency is poor (about 60%) and the downsizing is limited. According to the engine starter in the JP-U No. 63-110672, when the battery is dead and the electric motor gets out of order, the engine starter itself cannot be operated. 
     According to the Japanese Patent No. 2573340, on the other hand, the reduction gear mechanism of high reduction gear ratio is arranged between the electric motor and the spring barrel drum, the capacity of motor and the capacity of battery are respectively reduced to less than 1/10 and 1/6 in the cell starter method, and even when a compact battery is mounted, it would not lose a practical use. The reduction ratio of the reduction gear mechanism of high reduction gear ratio is set to remarkable degrees of 1/250 to 1/300. Therefore, it naturally takes a lot of time to rotate the spring barrel drum enough to accumulate a necessary pressure in the spring. In this engine starter, an automatic winding controller of spiral spring is provided, the power accumulating operation of the power accumulating spring is automatically performed by a control circuit of this controller in every starting operation, and the power supply to the motor is stopped by detecting a timer or the winding up of the spring, thereby reducing the waiting time of restart. As a result, the whole device becomes complicated, naturally its maintenance becomes troublesome, and accordingly the cost becomes expensive. Needless to say, the battery is built the device within, and the whole device upsizes so much. 
     According to the JP-U No. 2-13171, when the electric motor breaks down, the manual crank is operated to rotate the spring barrel drum through the ratchet wheel of small diameter, the spring is rewound to have the accumulated power, the starting ratchet is operated after removing the manual crank, to release the energy accumulated in the spring, hence to rotate the starter ratchet wheel and start the engine. However, during the rotation of the engine, the ratchet wheel of small diameter runs idle. In the JP-U No. 2-13171, since the respective axes of the electric motor, the spring barrel drum, the ratchet wheel of small diameter, and the ratchet claw are in parallel with each other, this extremely limits the downsizing of the engine starter. 
     In the JP-A No. 2002-285940, since the spring barrel drum is manually driven through the recoil driving mechanism in an emergency, the whole device comes to include the electric motor and its reduction mechanism in addition to the conventional recoiling engine starter, and further, since the reduction mechanism is composed of the warm gear and the warm wheel of the spring barrel drum, the electric motor shaft and the supporting shaft of the spring barrel drum cross at right angle, and therefore, it is difficult to downsize the whole device similarly to the JP-U No. 63-110672. 
     SUMMARY OF THE INVENTION 
     In order to solve the above conventional problems, the invention is to provide a compact electric engine starter in which an unnecessary part is eliminated, for the sake of rational design, downsizing and weight saving is improved to a high degree, the weight balance on the both sides of the whole engine becomes even, and further the engine can be started by hand. 
     The above-mentioned object is achieved by an engine starter having a compact electric motor driven by a battery power, a power accumulating unit which transmits the power of the compact electric motor through a high-speed reduction gear mechanism in a direction of accumulating power, and a power transmission unit which transmits the accumulated power of the power accumulating unit to a crank shaft of an engine, that is the fundamental structure of the invention, in which the battery is arranged outside the starter, the power accumulating unit has a spring and a rotation supporting member for supporting one end of the spring, the rotation supporting member having a first gear on its outer peripheral surface, a second gear is fixed to an output shaft of the high-speed reduction gear mechanism, the first and the second gears are engaged with each other, the power accumulating unit and the power transmission unit are arranged on the same first axis line and the compact electric motor and the high-speed reduction gear mechanism are arranged on the same second axis line parallel to the first axis line, and the second axis line where the compact electric motor is placed is arranged on a straight line, below the first axis line, connecting a gravity center of the whole engine, including peripheral units around a muffler and a carburetor, with the engine starter mounted thereon, and an axis line of the crank shaft. 
     Here, a spiral spring and a coil spring are used as the spring. When using the spiral spring, a spring barrel drum is used as the rotation supporting member. When using the coil spring as the spring, a general gear may be used as the rotation supporting member. It is preferable that a planetary reduction gear mechanism is used as the high-speed reduction gear mechanism and that a spur gear is used for the first and the second gears by combination with the planetary gear. 
     According to the preferable mode, it includes a rotation operating mechanism which can rotate an output shaft by hand and set the shaft end of the output shaft free or tight, being positioned on the axis line of the output shaft of the high-speed reduction gear mechanism. The power accumulating unit or the power transmission unit may be provided with a rotation preventing means which usually allows the rotation in a direction of releasing the power of the power accumulating unit or the power transmission unit but prevents the rotation in the direction of releasing the power, so as not to release the spring power accumulated in the power accumulating unit even when a hand is removed from the rotation mechanism at a halt of the electric motor, when having the rotation operating mechanism. When the power transmission unit has a starting pulley connected to the crank shaft through a switching means, it is preferable that the rotation preventing means is composed of a plurality of ratchet teeth formed on the outer periphery of the starting pulley that is one of the components of the power transmission unit and a releasing member for setting the ratchet tooth free or tight. 
     According to the invention, since the components integrated with the starter are the minimum, the recoil driving unit is eliminated, the battery is arranged outside the starter, and simultaneously, the arrangement of the units accommodated into the starter is designed most efficiently. Assuming the case where the electric motor cannot be driven, manual engine start is enabled in such an emergency. As a result, the whole starter can be downsized extremely, and in order to solve various problems of the Patent Documents 1 to 4, it is needless to say that ultra-compact units are used as the electric motor and the reduction gear mechanism. In addition to the weight saving by eliminating some units such as the battery and the recoil driving unit which have been built in the conventional device as well as the downsizing of the whole starter, the most rational design of most efficient arrangement is adopted in which the weight balance can be kept on the both sides of the engine with the engine starter mounted thereon at every operation of various working machines. 
     Namely, the battery and the start switch are not mounted on the starter, but they are provided on a handle, an operation unit of the working machine. The first axis line that is the rotation axis line common to the power accumulating unit, the power transmission unit, and the crank shaft is arranged in parallel to the second axis line that is the rotation axis line of the electric motor and the reduction gear mechanism, thereby shortening the measurement of the starter in the direction of the axis line and its orthogonal direction and reducing the arrangement space of these units to a minimum. While, the engine is provided with the auxiliary units around the muffler and the carburetor equally on the both sides of the engine integrally. The gravity center differs between on the muffler side and the carburetor side and the weight on the carburetor is heavier than that on the muffler side. On the other hand, the main body of the engine is substantially symmetric and the gravity center is on the vertical line halving the body. 
     Therefore, the gravity center of the whole engine is a little deviated toward the carburetor side with the crankshaft as a center. As a result, when the engine is supported on the crank shaft line, when the gravity center in the horizontal direction is ignored, the rotation torque inclining to one of the both sides with the crank shaft as a center always works in the engine so that the straight line connecting the gravity center and the crank shaft may be a vertical line. In order to make the rotation torque zero, the gravity center with the engine starter mounted should be on the vertical line halving the engine main body horizontally and the axis center of the crankshaft may be on the same vertical line ideally. Such arrangements, however, are very difficult because the setting space of the engine starter has various restrictions. 
     Therefore, the second axis line where the compact electric motor is placed, is arranged on a straight line, below the axis line of the crank shaft, connecting a gravity center of the whole engine, including peripheral units around a muffler and a carburetor, with the engine starter mounted thereon, and the axis line of the crank shaft. The electric engine starter according to the invention is symmetric and the gravity center is on the vertical line including the first axis line and the second axis line halving the engine starter horizontally. By arranging the compact electric motor as mentioned above, the gravity center of the whole engine with the engine starter mounted thereon is moved toward the straight line. This can improve the balance on the both sides of the whole engine with the starter mounted thereon, the power in a direction of straining the hand hardly works, and the fatigues occurring during the operation of the working machine caused by the unbalance are not accumulated, which enables the stable work for a long time. Needless to say, further downsizing is realized according as the number of the components is reduced. 
     When using the planetary reduction gear mechanism as the high-speed reduction gear mechanism, the axis line of the input unit and the axis line (second axis line) of the output shaft can be arranged in one line. This is arranged parallel to the first axis line, the first and the second gears are formed in the shape of the spur gear, the first gear of the power accumulating unit is engaged in the second gear of the reduction gear mechanism, and the first axis line and the second axis line are arranged on a same plane surface, hence to reduce the space exclusive for the units to a minimum degree. At the same time, when the rotation operating mechanism is provided with a removable unit provided on the shaft end portion of the output shaft of the reduction gear mechanism and a rotation operating member which sets the removable unit of the shaft end free or tight while moving forward and backward on the axis line in an emergency, it is not necessary to provide even a driving mechanism such as a ratchet wheel and a recoil driving mechanism rotated by the manual crank, which contributes to the further downsizing. 
     The planetary reduction gear mechanism is easily downsized as the high-speed reduction gear mechanism, and in the case of this invention, the reduction ratio is not set so largely at 1/250 to 1/300 like the Japanese Patent No. 2573340 but set at around 1/50 at the best by combination with the first gear, hence to shorten the starting time of the engine, namely, the time required for the power accumulating unit to get a necessary accumulated power. 
     As the rotation preventing means, a combination of a plurality of ratchet teeth formed on the outer periphery of the starting pulley connected through a switching means such as a centrifugal clutch and a releasing member to be engaged in the ratchet tooth is used, thereby making the operation of the rotation preventing means accurately and easily. When the above rotation operating mechanism is composed of the removal unit provided on the shaft end of the output shaft of the high-speed reduction gear mechanism and the rotation operating member which sets the removable unit of the shaft end free or tight while moving forward and backward on the axis line, the rotation operating member can be pushed into or pulled from the starter toward the removable unit of the shaft end externally. Further, since the distal end can be attached to the removable unit of the shaft end and the rotation operating member is rotated in a direction of accumulating the power by the power accumulating unit, the output shaft of the high-speed reduction gear is rotated to accumulate the power in the power accumulating unit. Here, although the electric motor rotates simultaneously, because of the high-speed reduction gear ratio, the rotation is a little and the rotation torque is small, and the output shaft of the high-speed reduction gear mechanism can be easily rotated by hand. 
     According to the above structure, normally an engine starts by activating the electric motor, to rotate the power accumulating unit in a direction of accumulating the power through the high-speed reduction gear mechanism and the second gear, and when the accumulated power exceeds the maximum load enough to start the engine, the engine automatically starts. When a battery is dead and the electric motor doesn&#39;t work, even when the output shaft of the reduction gear mechanism is operated manually by using the rotation operating mechanism, the power will be accumulated in the power accumulating unit and when the accumulated power exceeds the maximum load of the engine, the engine will start. Here, when the one-way rotation preventing means is provided in the power accumulating unit or the power transmission unit, when the rotation operating mechanism is operated, the output shaft of the high-speed reduction gear mechanism is rotated in a direction of accumulating the power by the power accumulating unit while preventing the rotation in the direction of releasing the power in the power accumulating unit or the power transmission unit, hence to accumulate a necessary power in the power accumulating unit. When a necessary power has been accumulated, the rotation operating mechanism is released, and the rotation preventing means is operated toward the releasing direction, hence to allow the rotation of the power accumulating unit or the power transmission unit. Simultaneously with the allowance, the power in the power accumulating unit is released, hence to start the engine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the electric engine starter according to the first embodiment of the invention and the engine at their assembly stage; 
         FIG. 2  an exploded perspective view showing the power accumulating unit, the power transmission unit, and one of the electric driving units of the electric engine starter in a magnified way; 
         FIG. 3  is a front view of an engagement state of the releasing means and the power transmission unit viewed from the back side in  FIG. 1 ; 
         FIG. 4  is a front view of a not-engagement state of the releasing means and the power transmission unit viewed from the back side in  FIG. 1 ; 
         FIG. 5  is a perspective view showing the driving wheel of the power transmission unit from the front side; 
         FIG. 6  is an exploded perspective view showing the important portion of the variation example in the first embodiment in a magnified way; 
         FIG. 7  is an exploded view of the electric engine starter according to the second embodiment of the invention and the engine at their assembly stage; 
         FIG. 8  is an exploded perspective view showing the power accumulating unit, the power transmission unit, and one of the electric driving units of the electric engine starter in a magnified way; 
         FIG. 9  is a front view of an engagement state of the releasing means and the power transmission unit viewed from the back side in  FIG. 7 ; 
         FIG. 10  is a front view of a non-engagement state of the releasing means and the power transmission unit viewed from the back side in  FIG. 7 ; 
         FIG. 11  is a perspective view showing the driving wheel of the power transmission unit from the front side; and 
         FIG. 12  is an exploded perspective view showing the important portion of the variation example in the second embodiment in a magnified way. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is an exploded view of an electric engine starter showing the first embodiment of the invention and an internal combustion engine at a stage of their assembly.  FIG. 2  to  FIG. 5  are views for use in describing the arrangement and the structure of each component of the engine starter in the first embodiment. The engine starter  100  of the invention is used for a compact air-cooled 2-cycle gasoline engine and the starter  100  is arranged near by an input end of a crankshaft  11  of the internal combustion engine  10 . 
     The engine starter  100  includes a power accumulating unit  110 , a power transmission unit  120 , and an electric driving unit  130 , and they are integrated together and accommodated in a single case  140 . The case  140  has a rectangular-shaped first space A for accommodating the power accumulating unit  110  and the power transmission unit  120  in the upper half in  FIG. 1  and an inverted triangular-shaped second space B narrowing downward for accommodating the driving unit  130  in its lower half in  FIG. 1 . The case  140  is formed by the equally divided structure of the first case  140   a  on the engine side and the second case  140   b  on its opposite side. 
     The upper half portion of the first case  140   a  on the side of engine is formed as a substantially rectangular window  141 , and a reduction gear insertion hole  142  for inserting a high speed reduction gear mechanism  132  described later that is one of the components of the electric driving unit  130  is formed in the middle of the lower half portion. Bolt insertion holes  143  for fixing the first case  140   a  to the engine  10  are formed at the four corners on the inner side of the rectangular window  141  and screw holes  144  for combining the first case  140   a  with the second case  140   b  are formed at four positions; on the upper two corners and the lower two corners of the frame of the rectangular window  141 . On the other hand, a shaft  145  is protruded toward the direction of the engine from the middle of the bottom inner surface which forms the first space A of the second case  140   b  on the opposite side of the engine, and a wrench insertion hole  146  for communicating with the inner space is formed on the back wall portion forming the second space B at the lower position perpendicular to the shaft  145  correspondingly to the center of the reduction gear insertion hole  142 . Bolt insertion holes  147  are respectively formed on the second case  140   b  at the positions corresponding to the screw holes  144  of the first case  140   a.    
     The power accumulating unit  110  includes a spring  111  and a spring barrel drum  112 , as illustrated in  FIG. 1  and  FIG. 2 , and a spur gear  113  is formed on the outer peripheral surface of the spring barrel drum  112  at its half portion. A through hole  112   a  is formed at the center of the spring barrel drum  112 , the outer wheel of the one-way clutch  114  of bearing shape is embedded in the through hole  112   a , and the shaft  145  is fixedly attached to the inner wheel of the one-way clutch  114 . Further, a spring housing space, not illustrated, is formed on the side of the engine of the spring barrel drum  112  and a fixing groove of an outer end, not illustrated, for fixing the outer end  111   a  of the spring  111  is formed on one portion of the peripheral surface of the spring housing space. 
     In the first embodiment, as mentioned above, although the spring barrel drum  112  is enabled to rotate in one direction by the one-way clutch  114  of bearing shape, another ratchet tooth  115 , instead of the one-way clutch  114 , may be formed on the outer peripheral surface of the spring barrel drum  112 , besides the spur gear  113 , as illustrated in  FIG. 6 , and the spring barrel drum  112  may be enabled to rotate in one direction even when a ratchet claw  116  to be engaged in the ratchet tooth  115  is supported rotatably on one portion of the second case  140   b . At this time, the ratchet claw  116  is always urged toward the direction to be engaged in the ratchet tooth  115  by a spring material  117  mounted on the second case  140   b . In this case, the spring barrel drum  112  is supported rotatably by the shaft  145  through a flat bearing  118 . 
     The power transmission unit  120  is formed by a starting pulley  121  and a releasing member  122  which is free or tight to the starting pulley  121 , as illustrated in  FIG. 2  to  FIG. 5  indicating one portion of  FIG. 1  magnified. A loose hole  121   a  for loosely inserting the shaft  145  protruding from the second case  140   b  is formed in the center of the starting pulley  121  and as illustrated in  FIG. 2 , a spring end fixing unit  121   b  protruding toward the spring barrel drum  112  in a way of surrounding the loose hole  121   a  is formed in the center of the starting pulley  121  on the opposite side of the engine. An inner end fixing groove  121   b  which fixedly attaches the inner end  111   b  of the spring  111  is formed on the spring end fixing unit  121   b . A screw hole, not illustrated, is formed on the distal end of the shaft  145 , a set screw  148  is screwed into the screw hole at a point of finishing the assembly, and the power accumulating unit  110  and the starting pulley  121  are accommodated into the second case  140   b . The axis line of the shaft  145  is a first axis line in the invention. 
     An engaged protruding portion  121   c , having the ratchet tooth  121   d  on the peripheral surface to be engaged in a catching claw that is one element of the centrifugal clutch mechanism mounted on a fan, not illustrated, integrated with the crank shaft  11  of the engine  10 , as illustrated in  FIG. 5 , is protruded in the center of the starting pulley  121  on the side of the engine. Although the engaged protruding portion  121   c  is at a halt, being engaged in the catching claw  12  mounted on the crank shaft  11 , while receiving the energy in a releasing direction occurring in the process of accumulating a spring force in the spring  111  through rotation of the spring barrel drum  112 , until the power of the spring exceeds the maximum load of the engine, the engaged protruding portion  121   c  as being engaged with the catching claw  12  starts rotating and makes the engine start when the accumulated power in the spring  111  exceeds the maximum load. When the rotation of the engine comes into a constant state, the catching claw  12  is released from the engagement with the engaged protruding portion  121   c  of the starting pulley  121  owing to the centrifugal power, and the rotation of the engine is maintained. 
     The ratchet teeth  123  are formed at predetermined intervals on the outer periphery of the starting pulley  121  and the whole starting pulley  121  is formed as a ratchet wheel. One end  122   b  of the releasing member  122  is supported rotatably by a boss  140   a - 1  of the first case  140   a , a push button  149  operates the rotation of its distal end  122   a , to set the outer peripheral ratchet tooth  123  of the starting pulley  121  free of tight, thereby enabling or disabling the rotation of the starting pulley  121 . The distal end  122   a  of the releasing member  122  is urged toward the direction of releasing itself from the ratchet tooth  123  by the spiral screw  150  and the distal end  122   a  can be engaged in the ratchet tooth  123  only by rotating the one end  122   b  against the spiral screw  150 . The releasing member  122  and the ratchet tooth  123  of the starting pulley  121  correspond to the rotation preventing means in the invention. 
     According to the embodiment, in order to rotate the distal end  122   a  of the releasing member  122  against the urged force, as illustrated in  FIG. 4  and  FIG. 5 , a ball portion  149   a  of a pin end of the push button  149  mounted on the outer peripheral portion of the first case  140   a  is embedded in the distal end  122   a  of the releasing member  122 , and the releasing member  122  is rotated toward the ratchet tooth  123  against the force of the spiral screw  150  by pushing the push button  149 . According to this pushing operation, the push button  149  is locked by a locking means, not illustrated, and by pulling the push button  149 , the lock is released and the releasing member  122  is rotated toward a direction of releasing the mesh with the ratchet tooth  123 . 
     Further, the releasing member  122  is fixed to the peripheral wall portion of the first case  140   a  by the force of the spiral screw  150 . 
     The electric driving unit  130  is formed by an ultra-compact direct current electric motor  131  and a high speed reduction gear mechanism  132  combined with the output shaft of the electric motor  131 , a high speed rotation of the electric motor  131  is reduced through the high speed reduction gear mechanism  132  and transmitted to the spring barrel drum  112 . The high speed reduction gear mechanism  132  is formed by a small-sized planetary gear mechanism  132   a  and the spur gear  132   b  fixed to the output shaft of the planetary gear mechanism  132   a . As the reduction gear mechanism  32 , a combination of the planetary gear mechanism  132   a  and the spur gear  132   b  is used, and therefore, the input unit and the output shaft can be arranged on the same axis line that is the second axis line of the invention, which enables the axis line to be parallel with the shaft  145  protruding from the second case  140   b  toward the engine. This makes it possible to eliminate the recoil mechanism completely, arrange the battery which has been hitherto arranged in the lower portion of the power accumulating unit  110  and the power transmission unit  120 , in the outside of the case  140 , for example, in an operation handle, not illustrated, of the working machine. As a result, the electric driving unit  130  is arranged in the empty space being formed, hence to make it possible to shorten the length of the axis line of the case  140  and shorten the lateral width of the case  140  to the minimum degree. 
     In this embodiment, the axis line of the electric driving unit  130  is arranged in the lower portion perpendicular to the shaft  145 . Strictly speaking, the axis center of the electric driving unit  130  is arranged at a position a little deviated from a line perpendicular to the axis center of the shaft  145 . Namely, a line L 1  connecting the axis center of the electric driving unit  130  and the axis center of the shaft  145  is not located at the vertical line L 2  but rotated around the shaft  145  for a smallest angle α, as illustrated in  FIG. 3 . Specifically, the setting position of the engine starter  100  is a little inclined toward the engine  10  itself and the engine starter  100  is set at the engine  10 .  FIG. 3  shows the smallest angle α magnified for the sake of easy understanding, but it is actually too small to be visible. 
     As mentioned above, the rotation axis line of the catching claw  12  of the centrifugal clutch mechanism mounted on the crank shaft  11  of the engine  10  and the rotation center of the starting pulley  121  of the power transmission unit  120  are on the first axis line in agreement. While, the axis line (second axis line) of the electric driving unit  130  may be arranged anywhere near the first axis line if only there is a space. In fact, when taking the downsizing of a device into consideration, the setting position of the engine starter, especially, its electric motor will be naturally definite. 
     The engine  10  is provided with a muffler  15  and a carburetor  16 , by way of example, symmetrically on the both sides of the crank shaft  11 , as illustrated in  FIG. 1 , additionally to the main body of the engine. The center of the gravity on the side of the muffler  15  is different from that on the side of the carburetor  16  and therefore, the center of the gravity of the whole engine  10  is a little deviated toward the side of the carburetor  16 . This small movement of the gravity center causes the generation of the rotation torque that weighs the engine toward the vertically lower portion of the gravity center (in a direction of gravitation), and when a user works by carrying the working machine, he or she may receive a force straining his or her hand at the operation. During working, the user tries to maintain the working position against this force, which fatigues him or her very much, and accumulation of the fatigues makes it difficult to work for a long time. The engine starter  100  of the invention, however, has the symmetrical figure and structure, although it has a little deviation as mentioned above, and the position of the gravity center may be considered to be on the vertical line which almost halves the body. 
     According to the embodiment, the axis line (second axis line) of the electric driving unit  130  is arranged in the vertically lower portion of the axis line (first axis line) of the shaft  145  in parallel, as mentioned above. By arranging the compact electric motor  131  like this, the gravity center of the whole engine with the engine starter  100  mounted thereon is moved to the direct line connecting the center of the crank shaft  11  and the shaft center of the electric motor  131 , and it is moved a little downwardly from the position of the gravity center of the engine  1  with no engine starter  100  mounted thereon. Therefore, the balance of the whole engine on the both sides with the engine starter  100  mounted thereon is improved, the rotation torque straining the user&#39;s hand at the working time is little generated, and fatigue during the operation of the machine caused by the unbalance can be reduced. 
     The planetary gear mechanism  132   a  according to the embodiment has first to third inner gears  132   a - 1  to  132   a - 3  that are ring-shaped sun gears, and the planetary gear mechanism  132   a  is to be fixedly accommodated into the motor housing case  134  together with the electric motor  131 . A plurality of projections  132   a ′- 1  to  132   a ′- 3  extending in parallel to the rotation shaft are provided on the outer peripheral surface of the first to third inner gears  132   a - 1  to  132   a - 3 , and the same number of fixing grooves  134   a - 1  for fixing the projections  132   a ′- 1  to  132   a ′- 3 , which extends in parallel to the axis line, are formed on the inner peripheral surface of the motor housing case  134  at the position corresponding to the projections  132   a ′- 1  to  132   a ′- 3 . 
     In the embodiment, the motor housing case  134  is formed in a cylindrical body having the bottom with an open end on the opposite side of the engine, and divided into a cylindrical main body  134   a  and a bottom  134   b . Projections  134   c  and  134   d  extending in parallel to the axis line are provided on the outer peripheral surface where the respective fixing grooves  134   a - 1  of the cylindrical main body  134   a  and the bottom  134   b  are formed, a screw hole is formed on the projection  134   d  of the bottom  134   b , and a bolt insertion hole is formed on the projection  134   c  of the cylindrical main body  134   a . The projections  132   a ′- 1  to  132   a ′- 3  of the planetary gear mechanism  132   a  are attached to the fixing grooves  134   a  of the motor housing case  134  having the above structure, hence to accommodate the electric motor  131  and the planetary gear mechanism  132   a  fixedly. The motor housing case  134  accommodating the electric motor  131  and the planetary gear mechanism  132   a  is embedded in the motor embedding opening  142  formed in the first case  140   a  and supported. At this time, the electric motor  131  and the planetary gear mechanism  132   a  accommodated into the motor housing case  134  are fastened through bolts and nuts, not illustrated, by a fixing frame  135  with the output shaft of the planetary gear mechanism  132   a  exposed to the outside. In this manner, the spur gear  132   a  is fixed to the distal end of the output shaft of the planetary gear mechanism  132   a  fixedly accommodated into the motor housing case  134 . 
     According to the embodiment, the reduction ratio between the compact electric motor  131  and the spring barrel drum  112  is set at 1/50. The reduction ratio between the spur gear  132   b  fixed to the output shaft of the planetary gear mechanism  132   a  and the spur gear  113  formed on the outer peripheral surface of the spring barrel drum  112  is set at 1/2.5. Therefore, the reduction ratio of the planetary gear mechanism  132   a  is set at 1/20. An engaged portion  133   a  to be engaged in, for example, a hexagonal wrench, not illustrated, is formed on the output shaft  133  of the planetary gear mechanism  132   a , namely, the end portion of the supporting shaft of the spur gear  132   b , and the center of a wrench insertion hole  146  formed on the back wall of the second case  140   b  is located on its axis line. 
     In order to accommodate the components according to thus constituted embodiment into the case  140  and to assemble them, the shaft  145  of the second case  140   a  is fixedly inserted into the through hole  112   a  of the spring barrel drum  112  with the one-way clutch  114  attached thereto. Here, the outer end of the spring  111  is fixed to the outer end fixing groove, not illustrated, formed on the peripheral wall of the spring housing space of the spring barrel dram  112 . Next, the inner end of the spring  111  is fixedly attached to the inner end fixing groove  121   b ′ of the spring end fixing unit  121   b  formed in the center of the starting pulley  121 . Then, the shaft  145  of the second case  140   a  is loosely inserted into the loose hole  121   a  penetrating the spring end fixing unit  121   b , and thereafter, the setscrew  147  is screwed into the screw hole of the distal end of the shaft  145 , hence to finish assembling the spring barrel drum  112  and the starting pulley  121  within the second case  140   b.    
     When assembling the electric driving unit  130  within the case  140 , the electric motor  131 , the planetary gear mechanism  132   a  and the spur gear  132   b  of the reduction gear mechanism  132  are previously set up as an assembly. The projections  132   a ′- 1  to  132   a ′- 3  formed on the outer peripheral surface of the planetary gear mechanism  132   a  of this assembly are inserted into the inner fixing grooves  142   a  of the reduction mechanism embedding hole  142  formed on the first case  140   a  and supported fixedly. Thereafter, it is fastened to a crank case  13  through the four bolt insertion holes  143  by the bolts  14  formed at the four corners of the rectangular window  141  of the first case  140   a . At the same time, the electric motor  131  is arranged at a predetermined position of the crankcase  13  and fixed there. 
     Thus, after fixing the first case  140   a  together with the electric driving unit  130  to the crank case  13 , the bolt  14  is screwed into the screw hole  144  of the first case  140   a  through the screw insertion hole  147  of the second case  140   b , and as mentioned above, the second case  140   b  with the power accumulating unit  110  and the power transmission unit  120  assembled there is integrally attached to the first case  140   a . When attaching the second case  140   b  to the first case  140   a , the other rotative end  122   c  of the releasing member  122  is attached to the outer ratchet tooth  123  of the starting pulley  121 . When the releasing member  122  is pivoted by the boss  140   a - 1 , its distal end  122   c  is urged in a direction of not being engaged in the ratchet tooth  123  unless the end portion  122   b  of the releasing member  122  is operated by the screw spring  150 . 
     In the electric engine starter  100  according to the embodiment having the above structure, as mentioned above, the recoil driving unit and the battery are eliminated from the case  140  similarly to the conventional art, the spring barrel drum  112  accommodating the spring  111  of the power accumulating unit  110  and the starting pulley  121  of the power transmission unit  120  are supported on the same shaft  145 , only the electric motor  131  that is the electric driving unit  130  and the planetary gear mechanism  132   a  and the spur gear  132   b  forming the reduction gear mechanism  132  are arranged on the axis line parallel to the shaft  145  at the lower position perpendicular to the shaft  145 , and ultra-compact ones are used as the electric motor  131  and the planetary gear mechanism  132   a . Therefore, they are accommodated in the case  140  extremely compactly. As a result, the case  140  itself, or the whole starter can be extremely downsized. 
     When the battery is charged, turning on a switch provided on, for example, a handle starts the rotation of the electric motor  131 , so as to start the engine  10  by the starter  100 , and then, the high speed reduction gear mechanism  132  composed of the planetary gear mechanism  132   a  and the spur gear  132   b  rotates the spring barrel drum  112  in a direction of accumulating the power of the spring  111  at the reduction ratio of 1/50. At this point, the releasing member  122  is not engaged in the starting pulley  121  of the power transmission unit  120 , but only the catching claw  12  mounted on the crankshaft  11  is just engaged in the engaged protruding portion  121   c  of the starting pulley  121 . 
     Here, in the process of rotating the spring barrel drum  112  and accumulating the power in the spring  111 , the force of releasing the accumulated power works on the spring  111 , hence to entering the process of rotating the crank shaft  11  and compressing the engine  10  through the catching claw  12 . The crankshaft  11 , however, cannot be rotated further before the sufficient power has been accumulated in the spring  111  so as to exceed the maximum load in the compression process. When the spring  111  has fully accumulated the power enough to exceed the maximum load in the compression process of the engine  10 , a force for releasing the accumulated power of the spring  111  becomes so stronger that the starting pulley  121  rotates the crank shaft  11  through the catching claw  12 , ignites the engine  10 , and starts the operation. When the rotation of the engine  10  comes into a constant operation, the catching claw  12  is removed from the engaged protruding portion  121   c  of the starting pulley  121  owing to its centrifugal force, hence to keep the rotation of the engine. The time required for starting the engine is very short and almost the same as the staring time by the usual cell starter in a car because the reduction ratio of the reduction gear mechanism is set relatively small. 
     The above is the starting procedure of the engine starter  100  in its normal state. According to the invention, when the electric motor  131  cannot be driven because the battery is dead due to some reasons or because of the failure of the motor itself, the engine  10  can be started manually. According to the embodiment, in the above emergency, at first, the push button  149  is pushed, to make the releasing member  122  into engagement in the ratchet tooth  123  of the starting pulley  121  against the urged force of the releasing member  122 . After confirming this engagement, for example, the hexagonal wrench, not illustrated, is inserted into the wrench insertion hole  146  formed on the back surface of the case  140  in  FIG. 1 , to be engaged in the engaged portion  133   a  formed on the end of the output shaft  133  of the reduction gear mechanism  132 . Next, by rotating the hexagonal wrench, the spur gear  132   b  of the reduction gear mechanism  132  is rotated, to rotate the spring barrel drum  112  in a direction of accumulating the power. At the same time, the compact electric motor  131  is to be rotated a little. Though the rotating operation of the hexagonal wrench is performed by hand, since the reduction gear mechanism  132  is interposed between the compact electric motor  131  and the spring barrel drum  112 , the rotation torque of the compact electric motor  131  is a little and there is no problem on the operation. 
     At the operating time of the wrench, since the above releasing member  122  is engaged in the starting pulley  121 , no power is transmitted between the starting pulley  121  and the crankshaft  11 . As a result, the wrench operation can be performed intensively at ease until the spring  111  has fully accumulated the power. When the spring  111  has accumulated the power enough to start the engine, the hexagonal wrench is removed from the wrench insertion hole  146  of the case  140  by releasing the engagement with the supporting shaft end of the spur gear  132   b , and the push button  149  is pushed to remove the releasing member  122  from the ratchet tooth  123  of the starting pulley  121 . At this point, since the spring  111  has accumulated the power enough to start the engine  10 , the engine starts rotation in the instant of releasing the engagement. 
     The power accumulating unit  110  is formed by the spring  111  and the spring barrel drum  112 , as illustrated in  FIG. 1  and  FIG. 2 , and the spur gear  113  to be continued in a peripheral direction is formed on the half of the outer peripheral surface of the spring barrel drum  112 . The through hole  112   a  is formed in the center of the spring barrel drum  112 , the outer wheel of the one-way clutch  114  of the bearing shape is closely attached to the through hole  112   a , and the shaft  145  of the second case  140   b  is loosely attached to the inner wheel of the one-way clutch  114 . The spring housing space, not illustrated, is formed in the spring barrel drum  112  on the side of the engine, and the outer end fixing groove, not illustrated, for fixing the outer end  111   a  of the spring  111  is formed on one portion of the peripheral wall of the spring housing space. 
     In the first embodiment, although the spring barrel drum  112  is designed to be rotatable only in one direction by the one-way crutch  111  of the bearing shape, as mentioned above, for example, another ratchet tooth  115 , instead of the one-way clutch  114  may be formed on the outer peripheral surface of the spring barrel drum  112 , besides the spur gear  113 , as illustrated in  FIG. 6 , and the ratchet claw  116  to be engaged in the ratchet tooth  115  may be rotatively supported on one portion of the second case  140   b , in order to allow the spring barrel drum  112  to rotate only in one direction. Here, the ratchet claw  116  is similarly urged toward the direction of being engaged in the ratchet tooth  115  by a spring member  117  mounted on the second case  140   b . In this case, the spring barrel drum  112  is rotatively supported by the shaft  145  through the ordinary flat bearing  118 . 
       FIG. 7  shows an exploded view of the engine starter according to the second embodiment of the invention and the engine at their assembly time,  FIG. 8  is an exploded view magnifying the main portion of the engine starter,  FIG. 9  is a back side view of  FIG. 7  showing the engaged state of a releasing means in a driving pulley,  FIG. 10  is a back side view of  FIG. 7  showing the non-engaged state of the releasing means, and  FIG. 11  is a perspective view seen from the front surface of the driving pulley. The second embodiment is different from the first embodiment in the power accumulating unit  210  and the power transmission unit  220  as apparent from  FIG. 1 , and the other components of the engine  10 , the case  140 , and the electric driving unit  130  are the same as those of the first embodiment. Therefore, the same reference numerals are attached to the same components, with the same terms used, other than the power accumulating unit  210  and the power transmission unit  220 . 
     Therefore, in the following description, the power accumulating unit  210  and the power transmission unit  220  will be mainly described more concretely with reference to  FIG. 2 . 
     The power accumulating unit  210  according to the second embodiment includes a coil spring  211  and a coil spring end supporting gear  212 , as illustrated in  FIG. 7  and  FIG. 8 , and a spur gear  213  to be continued in a peripheral direction is formed on the half of the outer peripheral surface of the coil spring end supporting gear  212 . A through hole  212   a  is formed in the center of the coil spring end supporting gear  212 , an outer wheel of the one-way clutch  214  of the bearing shape is closely attached to the through hole  212   a , and the shaft  145  of the second case  140   b  is inserted into the inner wheel of the one-way clutch  214 . An outer end fixing hole, not illustrated, for fixing the one end  211   a  of the coil spring  211  is formed on one portion of the coil spring end supporting gear  212  on the side of the engine. 
     Even in the second embodiment, although the coil spring end supporting gear  212  is designed to be rotatable only in one direction through the one-way clutch  114  of the bearing shape as mentioned above, for example, another ratchet tooth  215 , instead of the one-way clutch  214 , may be formed on the outer peripheral surface of the coil spring end supporting gear  212 , besides the spur gear  213 , as illustrated in  FIG. 12 , and a ratchet claw  216  to be engaged in the ratchet tooth  215  may be formed on one portion of the second case  140   b , hence to allow the coil spring end supporting gear  212  to rotate only in one direction, similarly to the first embodiment. Here, the ratchet claw  216  is similarly urged toward the direction of being engaged in the ratchet tooth  215  by a spring member  217  mounted on the second case  140   b . Also in this case, the coil spring end supporting gear  212  is rotatively supported by the shaft  145  of the second case  140   b  through an ordinary flat bearing  218  similarly to the first embodiment. 
     On the other hand, the power transmission unit  220  is formed by a starting pulley  221  and the releasing member  122  which releases the starting pulley  221 , as illustrated in  FIG. 8  to  FIG. 11 . A loose hole  221   a  for loosely inserting the shaft  145  protruding from the second case  140   b  is formed in the center of the starting pulley  221  and as illustrated in  FIG. 2 , a spring end fixing unit  221   b  protruding toward the coil spring end supporting gear  212  is formed in the center of the starting pulley  221  on the opposite side of the engine in a way of surrounding the loose hole  221   a . An attaching unit  221   b ′ for attaching and supporting the other end  211   b  of the coil spring  211  is formed on the coil spring end fixing unit  221   b  and the other end  211   b  is fixedly supported. Also in the second embodiment, the axis line of the shaft  145  becomes the first axis line of the invention. 
     An engaged protruding portion  221   c , having the ratchet tooth  221   d  on the peripheral surface to be engaged in the catching claw  12  that is one element of the centrifugal clutch mechanism mounted on a fan, not illustrated, fixed to the crank shaft  11  of the engine  10 , as illustrated in  FIG. 11 , is protruded in the center of the starting pulley  221  on the side of the engine, similarly to the first embodiment. Although the engaged protruding portion  221   c  is at a halt, being engaged in the catching claw  12  mounted on the crank shaft  11 , while receiving the energy in a releasing direction occurring in the process of accumulating a spring force in the coil spring  211  through rotation of the coil spring end supporting gear  212 , until the power of the spring exceeds the maximum load of the engine, the engaged protruding portion  221   c  as being engaged in the catching claw  12  starts rotating and makes the engine start when the accumulated power in the coil spring  211  exceeds the maximum load. When the rotation of the engine comes into a constant state, the catching claw  12  is released from the engagement with the engaged protruding portion  221   c  of the starting pulley  221  owing to the centrifugal power and the rotation of the engine is maintained. 
     The ratchet teeth  123  are formed at predetermined intervals on the outer periphery of the starting pulley  221  and the whole starting pulley  221  is formed as a ratchet wheel. One end  122   b  of the releasing member  122  is supported rotatably by the boss  140   a - 1  of the first case  140   a , the push button  149  operates the rotation of its distal end  122   a , to set the outer peripheral ratchet tooth  223  of the starting pulley  221  free or tight, thereby to allow or disable the rotation of the starting pulley  221 . The distal end  122   a  of the releasing member  122  is urged toward the direction of releasing itself from the ratchet tooth  123  by the spiral screw  150  at the ordinary engine start and the distal end  122   a  can be engaged in the ratchet tooth  123  only by rotating the one end  122   b  against the urged force of the spiral screw  150 . The releasing member  122  and the ratchet tooth  223  of the starting pulley  221  correspond to the rotation preventing means in the invention. The operation or the movement of the releasing member  122  is the same as that in the first embodiment, and its description is omitted. 
     In the electric engine starter  100  according to the second embodiment having the above structure, as mentioned above, the conventional recoil driving unit and battery are eliminated from the case  140 , the coil spring end supporting gear  212  accommodating the coil spring  211  of the power accumulating unit  210  and the starting pulley  221  of the power transmission unit  120  are supported on the same shaft  145 , only the electric motor  131  that is the electric driving unit  130  and the planetary gear mechanism  132   a  and the spur gear  132   b  forming the reduction gear mechanism  132  are arranged on the axis line (second axis line) parallel to the shaft  145  in the vertical lower portion of the shaft  145 , and ultra-compact motors are used as the electric motor  131  and the planetary gear mechanism  132   a . Therefore, they are accommodated in the case  140  extremely compactly. As a result, the whole starter can be extremely downsized even in the second embodiment. 
     By the arrangement of the above-mentioned electric motor  131 , similarly to the first embodiment, the gravity center of the whole engine with the engine starter  100  mounted thereon is moved toward the straight line connecting the center of the crank shaft  11  and the shaft center of the electric motor  131 , and it is moved a little downwardly from the position of the gravity center of the engine  1  with no engine starter  100  mounted thereon. Therefore, the balance of the whole engine on the both sides with the engine starter  100  mounted thereon is improved and its position is lowered, the rotation torque straining the user&#39;s hand at the working time is little generated, fatigue during the operation of the working machine caused by the unbalance can be reduced, and the stable work can be continued for a long time. 
     When the battery is charged, for example, the starter  100  can easily start the rotation of the engine  10  through turning on a switch provided on a handle. However, when the electric motor  131  cannot be driven because the battery is dead due to some reasons or because of the failure of the motor itself, the engine  10  can be started by hand. According to the embodiment, in the above emergency, at first, the push button  149  is pushed, to make the releasing member  122  into engagement with the ratchet tooth  223  of the starting pulley  121  against the urged force of the releasing member  122 . After confirming this engagement, for example, the hexagonal wrench, not illustrated, is inserted into the wrench insertion hole  146  formed on the back surface of the case  140  in  FIG. 7 , to be engaged in the engaged portion  133   a  formed on the end of the output shaft  133  of the reduction gear mechanism  132 . Next, by rotating the hexagonal wrench, the spur gear  132   b  of the reduction gear mechanism  132  is rotated, to rotate the coil spring end supporting gear  212  in a direction of accumulating the power. At the same time, the compact electric motor  131  is to be rotated a little. Though the rotating operation of the hexagonal wrench is performed by hand, since the reduction gear mechanism  132  is interposed between the compact electric motor  131  and the coil spring end supporting gear  212 , the rotation torque of the compact electric motor  131  is a little and there is no problem on the operation. 
     At the operating time of the wrench, since the above releasing member  122  is engaged in the starting pulley  221 , as mentioned above, no power is transmitted between the starting pulley  221  and the crankshaft  11 . As a result, the wrench operation can be performed intensively at ease until the coil spring  211  has fully accumulated the power. In this manner, when the coil spring  211  has accumulated the power enough to start the engine, the hexagonal wrench is removed from the wrench insertion hole  146  of the case  140  by releasing the engagement with the supporting shaft end of the spur gear  132   b  and the push button  149  is pushed to remove the releasing member  122  from the ratchet tooth  223  of the starting pulley  221 . At this point, since the coil spring  211  has accumulated the power enough to start the engine  10 , the engine starts the rotation at the moment when the engagement is released. 
     As apparent from the above description, according to the electric engine starter of the invention, since the battery is arranged outside of the device and the conventionally well-known recoil driving unit is removed therefrom, by the efficient arrangement of the working members, downsizing and weight saving of the whole device can be realized, and when the electric motor cannot be driven, the engine can be started by manual operation easily and safely, similarly to the conventional electric engine starter. Further, according to the invention, since the electric motor is arranged in consideration of the position of the gravity center of the whole engine with the engine starter mounted thereon, the lateral balance of the engine with the starter is improved, without feel of straining the hand during the operation of the working machine, and the stable operation with less fatigue during the operation is possible.