Starter

Information

  • Patent Grant
  • 6694941
  • Patent Number
    6,694,941
  • Date Filed
    Monday, December 17, 2001
    23 years ago
  • Date Issued
    Tuesday, February 24, 2004
    20 years ago
Abstract
There is provided a recoil starter which is capable of inhibiting settling and bending in the spiral spring of spiral spring mechanism, thus improving the durability of the spiral spring and preventing the internal hook end of the spiral spring from being easily disengaged from the core portion. The spiral spring mechanism comprises a spiral spring case placed close to the driving member, a actuating pulley placed close to the driven member, a spiral spring interposed between the spiral spring case and the actuating pulley, and means for rotating the spiral spring case only unidirectionally, wherein the outer and inner ends of the spiral spring are fastened to the spiral spring case and the actuating pulley, respectively.
Description




BACKGROUND OF THE INVENTION




The present invention relates to a recoil starter which is adapted for use in an internal combustion engine, and in particular, to a recoil starter provided with a buffering/power-accumulating means which is interposed between a driving member comprising a rope reel which is designed to be rotated by the pulling of a recoil rope, and a driven member to which the torque of the driving member is transmitted.




A conventional recoil starter which is designed to be mounted on an internal combustion engine is generally provided with a driving member comprising a rope reel around which a recoil rope is wound, and a driven (idler) member comprising a centrifugal ratchet mechanism. When the internal combustion engine is desired to be started, the recoil rope (recoil handle) is pulled to revolve the rope reel, the resultant revolution of the rope reel being then transmitted, via the driven member, to a crankshaft of the internal combustion engine to thereby start the internal combustion engine.




As set forth in Japanese Patent Application No. H11-238642, the present inventors have previously proposed a modification of the aforementioned recoil starter, wherein a spiral spring mechanism is interposed, as the buffering/power-accumulating means, between the driving member and the driven member.




According to this modified recoil starter, since the spiral spring mechanism is interposed, as the buffering/power-accumulating means, 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 to the top dead center thereof) in the pulling operation of the recoil rope (recoiling operation), and at the same time, 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, thus enabling even a person having a weak physical strength to easily start the internal combustion engine.




However, this modified recoil starter previously proposed by the present inventors is accompanied with the following possible problems.




Namely, since this modified recoil starter is designed such that the spiral spring of the spiral spring mechanism is rewound so as to accumulate the pulling force during the first-half driving process in the pulling operation of the recoil rope (recoiling operation), that during the latter-half driving process, the pulling force thus accumulated during the first-half driving process is released, thus unwinding the spiral spring and enabling the spiral spring to be restored to the original released state thereof, while permitting the spiral spring mechanism to rotate in the direction to drive the crankshaft, and that after the start-up of the internal combustion engine, the interlocking engagement between the spiral spring mechanism and the internal combustion engine is permitted to be released due to the releasing action by the centrifugal ratchet mechanism attached to the driven member, thus rendering the spiral spring mechanism to become free, the spiral spring is permitted, due to the inertia of the releasing movement of the spiral spring, to be excessively kicked back in the unwinding direction (releasing direction) even after the spiral spring has taken the fully unwound and released state thereof.




Generally, a spiral spring is usually employed, as in the case of a watch, under the conditions where the spiral spring is completely wound up and is then incompletely unwound leaving one or two unreleased turns. In the case of the aforementioned recoil starter however, since the spiral spring mechanism is rendered free after the start-up of the internal combustion engine, the spiral spring is completely released without leaving even a single unreleased turn, and is still more permitted to be excessively kicked back in the unwinding direction. Namely, the spiral spring is not used in a manner which the spiral spring is inherently intended to.




Therefore, the innermost end region of the spiral spring is repeatedly and locally subjected to a winding/unwinding stress, thus giving rise to the generation of settling and bending at this innermost end region of the spiral spring. As a result, not only the durability of the spiral spring is badly affected, but also the internal hook end of the spiral spring which is fastened to the core portion of the actuating pulley of spiral spring mechanism tends to be disengaged from the core portion, thereby raising a possibility that the rope-pulling manipulation may result in a futile try.




The present invention has been made in view of the aforementioned problems, and therefore, it is an object of the present invention to provide a recoil starter having a spiral spring mechanism interposed, as a buffering/power-accumulating means, between a driving member comprising a rope reel which is designed to be rotated by the pulling of a recoil rope, and a driven member to which the torque of the driving member is transmitted, the recoil starter being characterized in that it is capable of inhibiting the generation of settling and bending in the spiral spring of the spiral spring mechanism, thereby making it possible not only to improve the durability of the spiral spring, but also to prevent the internal hook end of the spiral spring from being easily disengaged from the core portion of the actuating pulley of spiral spring mechanism. Another object of the present invention is to provide a spiral spring which is excellent in durability and therefore is suited for use in the recoil starter, etc.




BRIEF SUMMARY OF THE INVENTION




With a view to attaining the aforementioned object, there is provided, in accordance with the present invention, a recoil starter which fundamentally comprises a driving member having a rope reel around which a recoil rope is wound to thereby enable the rope reel to be rotated by pulling the recoil rope, a driven (idler) member to which the torque of the driving member is transmitted, and a buffering/power-accumulating means interdisposed 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 impact to the driven member, the accumulated power being subsequently employed to drive the driven member, and wherein the spiral spring mechanism is rendered free after the start-up of an internal combustion engine.




In this case, the spiral spring mechanism is featured in that it comprises a spiral spring case placed close to the driving member, a actuating pulley placed close to the driven member, a spiral spring interposed between the spiral spring case and the actuating pulley, and means for rotating the spiral spring case only unidirectionally, wherein an outer end portion of the spiral spring and an inner end portion of the spiral spring are fastened to the spiral spring case and the actuating pulley, respectively.




In a preferable embodiment of the present invention, the spiral spring of the spiral spring mechanism comprises an outer circumferential wound portion where a predetermined number of turns of the outer circumferentially wound portion of the spiral spring are closely contacted with each other under a freely released condition of the spiral spring, and an inner circumferential wound portion which is constituted by at least one turn of the inner circumferentially wound portion of the spiral spring, wherein a clearance is provided between the outer circumferential wound portion and the inner circumferential wound portion. More preferably, the outer circumferential wound portion is constituted by a third turn and the following turns successive to the third turn, and the inner circumferential wound portion is constituted by a first turn and at least a portion of the second turn which is closely contacted with the first turn.




In another preferred embodiment of the present invention, the recoil starter is featured in that the actuating pulley is provided with a core portion around which the spiral spring is wound, that the spiral spring is provided, at an inner end portion thereof, with a C-shaped or ring-shaped internal hook end, that said core portion is provided with an inner end-holding portion into which the internal hook end is adapted to be inserted and held therein, that the spiral spring is provided, at an outer end portion thereof, with an external hook end, and that the spiral spring case is provided, at an outer circumferential wall thereof, with an outer end-holding portion with which the external hook end is adapted to be engaged.




Preferably, the inner end portion of the spiral spring is positioned, under a freely released condition of the spiral spring, at a position which is displaced from the location of the outer end portion of the spiral spring by a predetermined angle toward the direction which is opposite to the driving direction. Further, the rotational axial line of the spiral spring mechanism is preferably displaced from the proper center of the spiral spring by a predetermined distance toward the outer end portion of the spiral spring.




In a further preferable embodiment of the present invention, the outer diameter of the core portion of actuating pulley is made almost identical with the effective inner diameter of the first turn of the spiral spring. At the same time, the effective outer diameter of the spiral spring under the freely released condition thereof is made almost identical with the effective inner diameter of the spiral spring case. Further, the effective inner diameter of the first turn of the spiral spring and the effective outer diameter of the core portion are set to 25 mm or more (preferably, 30 mm or so).




In another preferred embodiment of the recoil starter of the present invention, the driving member is provided with a recoiling urging means for reversely revolving the rope reel so as to rewind the recoil rope, and also with a recoil ratchet mechanism for transmitting the torque of the rope reel to the spiral spring case.




The means for rotating the spiral spring case only unidirectionally is preferably constituted by a one-way clutch. Further, the driven member is preferably provided with an interlocking pulley having a power transmission mechanism through which the driven member is enabled to interlockingly coupled with the driving member. In this case, the power transmission mechanism may preferably be constituted by a centrifugal ratchet mechanism.




Meanwhile, the spiral spring according to the present invention comprises an outer circumferential wound portion where a predetermined number of turns of the outer circumferentially wound portion of the spiral spring are closely contacted with each other under a freely released condition of the spiral spring, and an inner circumferential wound portion which is constituted by at least one turn of the inner circumferentially wound portion of the spiral spring, wherein a clearance is provided between the outer circumferential wound portion and the inner circumferential wound portion.




More preferably, the outer circumferential wound portion is constituted by a third turn and the following turns successive to the third turn, and the inner circumferential wound portion is constituted by a first turn and at least a portion of the second turn which is closely contacted with the first turn. More preferably, the inner end portion of the spiral spring is positioned, under a freely released condition of the spiral spring, at a position which is displaced from the location of the outer end portion of the spiral spring by a predetermined angle toward the direction which is opposite to the driving direction.




More preferably, the effective inner diameter of the first turn of the spiral spring is set to 25 mm or more. The spiral spring according to the present invention may preferably be formed of a stainless steel sheet having a thickness of 0.5 to 0.7 mm. It is also preferable that an annealing treatment is performed on the inner circumferential wound portion of the spiral spring.




In the embodiment of the recoil starter where the spiral spring of the present invention which is constructed as mentioned above is employed, since at least a portion of the second turn is closely contacted with the first turn at the inner circumferentially wound portion of the spiral spring, even if the interlocking between the spiral spring mechanism and the engine is disengaged from each other after the start-up of the engine due to the free releasing effects to be obtained from the centrifugal ratchet mechanism mounted on the driven member, thereby rendering the spiral spring mechanism into a free state, and hence permitting the spiral spring to be excessively kicked back in the unwinding direction (releasing direction) thereof beyond the predetermined full unwound state of the spiral spring due to the inertia on this occasion, this kick-back stress to be repeated by the effects of rewinding-releasing (unwinding) on this occasion can be received by the entire body of the inner circumferentially wound portion, thereby making it possible to suppress the generation of a concentration of the stress in the vicinity of the internal hook end of the spiral spring.




As a result, the generation of settling or breakage of the spiral spring can be prohibited, thereby making it possible to improve the durability of the spiral spring, and at the same time, the internal hook end of the spiral spring can be prevented from being easily disengaged from the core portion provided at the actuating pulley of the spiral spring mechanism, thereby further improving the reliability of the starter.











BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING





FIG. 1

is a cross-sectional view of a starter representing one embodiment of the recoil starter according to the present invention;





FIG. 2

is a partially cut out perspective view showing a recoil ratchet mechanism which is interposed between the rope reel and the spiral spring case, which are designed to be installed in the recoil starter shown in

FIG. 1

;





FIGS. 3A and 3B

show respectively an enlarged sectional view taken along the line III—III of

FIG. 1

;





FIG. 4

is a partially cut out exploded perspective view showing a spiral spring mechanism which is designed to be installed in the recoil starter shown in

FIG. 1

;





FIG. 5

is an enlarged view showing a freely released state of the spiral spring before the spiral spring is installed in the recoil starter shown in

FIG. 1

;





FIG. 6

is a cross-sectional view taken along the line VI—VI of

FIG. 1

; and





FIG. 7

is a sectional view taken along the line VII—VII of FIG.


1


.











DETAILED DESCRIPTION OF THE INVENTION




Next, one embodiment of the starter according to the present invention will be explained with reference to the drawings.





FIG. 1

is a cross-sectional view of a starter representing one embodiment of the recoil starter according to the present invention. Referring to these

FIG. 1

, the recoil starter


5


shown therein is designed so as to be disposed close to one end


2




a


of a crankshaft


2


of an internal combustion engine


1


such as a small air-cooled internal combustion engine of 23 mL to 50 mL in displacement. This recoil starter


5


comprises a case


11


which is adapted to be mounted on one sidewall of the internal combustion engine


1


. This case


11


is composed of a two-piece structure forming a cylindrical structure. Inside an outer case member


11




a


of the case


11


, which is located away from the internal combustion engine


1


, there is disposed a driving member


6


which is adapted to be revolved through pulling manipulation of a recoil rope


21


(recoil handle


22


). On the other hand, inside an inner case member


11




b


of the case


11


, which is located close to the internal combustion engine


1


, there is disposed a driven member


7


which is adapted to be revolved independent from the driving member


6


.




More specifically, an anchoring shaft


12


is disposed extending coaxially from the center of the outer case member


11




a


. A rope reel


20


having the recoil rope


21


wound there a round is rotatably fitted on the proximal end portion of the anchoring shaft


12


, and a buffering/power-accumulating spiral spring mechanism


15


comprising a spiral spring case


16


acting as an interlocking rotational body, an actuating pulley


17


and a buffering/power-accumulating spiral spring


18


is rotatably fitted on the protruded end portion of the anchoring shaft


12


, i.e. at an intermediate portion between the rope pulley


20


and an interlocking pulley


35


constituting a driven member


7


so as to permit the buffering/power-accumulating spiral spring means


15


to be rotated independent from the rope pulley


20


. At the same time, a stopper screw


14


is screw-engaged with the protruded end portion of the anchoring shaft


12


.




In this case, the central axial line of the anchoring shaft


12


, the rotational axial line of the rope pulley


20


, the rotational axial line of the buffering/power-accumulating spiral spring means


15


, and the rotational axial line of the interlocking pulley


35


constituting the driven member


7


are all disposed so as to lie on the rotational axial line O of the crankshaft


2


, so that the rotation of the rope pulley


20


is enabled to be transmitted via the buffering/power-accumulating spiral spring means


15


and the interlocking pulley


35


to the crankshaft


2


of the internal combustion engine


1


.




As clearly seen from

FIGS. 4

to


6


in addition to

FIG. 1

, the buffering/power-accumulating spiral spring means


15


comprises the spiral spring case


16


which is disposed close to the driving member


6


, the actuating pulley


17


which is disposed close to the driven member


7


, and the spiral spring


18


which is interposed between the spiral spring case


16


and the actuating pulley


17


, wherein the buffering/power-accumulating spiral spring


18


is interposed between the spiral spring case


16


disposed on the input side and the actuating pulley


17


on the output side. Further, the spiral spring case


16


and the actuating pulley


17


are coaxially arranged so as to lie on the same axis, thereby enabling them to be rotated relative to each other. As described hereinafter, the outer end portion of the spiral spring


18


is secured to the spiral spring case


16


, while the inner end portion thereof is secured to the actuating pulley


17


, so that when either one of the spiral spring case


16


and the actuating pulley


17


is rotated relative to the other, the torque thereof is permitted to be given to the other.




More specifically, as clearly shown in

FIG. 5

where the spiral spring


18


is shown as it is taken out of the spiral spring mechanism


15


(a freely released state thereof before being assembled), the spiral spring


18


is provided, at the outer end portion thereof, with a U-shaped external hook end


18




a


, and at the inner end portion thereof, with an annular internal hook end


18




b


. In a freely released state of the spiral spring


18


, an outer circumferential wound portion Mo where a predetermined number of turns of the spiral spring


18


are closely contacted is formed, and an inner circumferential wound portion Mi which is constituted by at least one turn is formed, wherein a clearance (S) is provided between the outer circumferential wound portion Mo and the inner circumferential wound portion Mi.




More specifically, the outer circumferential wound portion Mo is constituted by a third turn N


3


of the spiral spring


18


and the following turns (including the outermost turn Nz) successive to the third turn N


3


, while the inner circumferential wound portion Mi is constituted by a first turn N


1


of the spiral spring


18


and at least a portion of the second turn N


2


which is closely contacted with the first turn N


1


. Further, in a freely released state of the spiral spring


18


as shown in

FIG. 5

, the annular internal hook end


18




b


is positioned so as to be displaced from the location of the external hook end


18




a


by a predetermined angle γ (40 to 50 degrees in this embodiment) toward the direction L which is opposite to the driving direction R to be explained hereinafter. By the way, this angle γ is an angle formed between a straight line C passing through the center K of the spiral spring


18


and through the center P of the external hook end


18




a


(or of an external end-fastening stub


16


C which is formed in the spiral spring case


16


), and a straight line F passing through the center K of the spiral spring


18


and through the center Q of the internal hook end


18




b


(or of an internal end-fastening portion


17


C which is formed in the actuating pulley


17


as explained hereinafter).




The spiral spring


18


is formed of a stainless steel sheet having a thickness of 0.5 to 0.7 mm, and the effective inner diameter Di of the first turn N


1


is set to about 30 mm. An annealing treatment is performed on the inner circumferential wound portion Mi of the spiral spring


18


(at least the first turn N


1


and the second turn N


2


thereof).




The spiral spring case


16


is provided with a cylindrical boss portion


16




a


at the center of a sidewall thereof facing the driving member


6


. A one-way clutch


19


is interposed between the inner peripheral wall of the cylindrical boss portion


16




a


and the anchoring shaft


12


, so that the spiral spring case


16


is rotatably supported by the anchoring shaft


12


in such a manner that it can be rotated unidirectionally (in the rewinding direction of the spiral spring


18


) about the anchoring shaft


12


. The spiral spring case


16


is further provided, on one of the sidewalls thereof facing the driven member


7


, with a projected short cylindrical portion


16


A for housing the spiral spring


18


. This spiral spring-housing cylindrical portion


16


A is provided with a disengagement-preventing protruded portion


16


B which is outwardly projected in the radial direction for housing therein the external hook end


18




a


of the spiral spring


18


. Inside this protruded portion


16


B, there is disposed the external end-fastening stub


16


C having an oval cross-section, which is protruded toward the driven member


7


so as to be fixedly fitted with the external hook end


18




a.






The actuating pulley


17


is provided, at the center of the sidewall thereof facing the driving member


6


, with a projected cylindrical boss portion


17


B which is rotatably fitted on the anchoring shaft


12


. This cylindrical boss portion


17


B is provided on the outer circumferential wall thereof with a core portion


17


A around which the spiral spring


18


is designed to be wound. This core portion


17


A is provided with the internal end-fastening portion


17


C forming a longitudinal groove having a U-shaped cross-section so as to enable the ring-shaped internal hook end


18




b


of the spiral spring


18


to be fitted and engaged therewith.




The outer diameter of the core portion


17


A is made almost identical with the effective inner diameter Di of the first turn N


1


of the spiral spring


18


. The effective outer diameter Do of the spiral spring


18


under the freely released condition thereof is made almost identical with the effective inner diameter of the spiral spring-housing cylindrical portion


16


A of the spiral spring case


16


.




Additionally, according to this embodiment, the rotational axial line O of the spiral spring mechanism


15


is displaced from the proper center K of the spiral spring


18


shown in

FIG. 5

by a predetermined distance “e” toward the external hook end


18




a


. In other words, under the assembled condition of the spiral spring mechanism


15


, where the spiral spring


18


is housed inside the spiral spring-housing cylindrical portion


16


A of the spiral spring case


16


, where the core portion


17


A of the actuating pulley


17


is fitted in the inner circumferential wound portion Mi of the spiral spring


18


, and where the external hook end


18




a


and internal hook end


18




b


of the spiral spring


18


are anchored to the external end-fastening stub


16


C and the internal end-fastening portion


17


C, respectively, the center of the inner circumferential wound portion Mi of the spiral spring


18


is decentered from the proper center K of the spiral spring


18


by the predetermined distance “e” toward the external hook end


18




a


. As a result, the range of contact between the first turn N


1


and the second turn N


2


of the spiral spring


18


is increased, thereby improving the retention force of the spiral spring


18


to wind around the core portion


17


A of the actuating pulley


17


.




On the other hand, between the outer case member


11




a


and the spiral spring case


16


, there is disposed a rope pulley


20


having a stepped disc-like configuration. This rope pulley


20


is provided on the outer peripheral wall thereof with annular groove


20




a


so as to enable the recoil rope


21


to be wound around it. This rope pulley


20


is further provided at the center of inner periphery thereof with a cylindrical boss


26


which is designed to be rotatably fitted on the cylindrical boss portion


16




a


of the spiral spring case


16


. This cylindrical boss


26


is provided with a pair of claw-retaining portions


27


A and


27


B to be engaged with a recoil ratchet mechanism


40


, and a pair of spring retaining portions


28


A and


28


B each corresponding to the claw-retaining portions


27


A and


27


B, respectively. These spring retaining portions


28


A and


28


B as well as claw-retaining portions


27


A and


27


B are respectively spaced apart from each other by an angle of 180 degrees and radially extended outward, thereby forming a cross-shaped or -shaped configuration constituted by a total of these four portions.




In the same manner as in the case of the conventional recoil type starter, although details are not shown in the drawings, one end of the rope


21


is fastened to a bottom portion of the groove


20




a


, while the other end of the rope


21


which is extended out of the outer case member


11




a


is fastened to a recoil handle


22


(see FIG.


7


).




Further, between the rope reel


20


and the outer case member


11




a,


there is interposed a recoil spiral spring


23


, the outer end of which being fastened to the rope reel


20


, and the inner end of which being fastened to a central portion of the outer case member


11




a


. The rope reel


20


is designed to be rotated by pulling the rope


21


, and then allowed to return to the original portion on account of the restoring force accumulated in the recoil spiral spring


23


, thereby enabling the rope


21


to be automatically wound up.




The recoil ratchet mechanism


40


is interposed between the rope reel


20


and the spiral spring case


16


.




As clearly seen from

FIGS. 2 and 3

, the recoil ratchet mechanism


40


comprises, on one of the sidewalls of the rope pulley


20


facing the spiral spring case


16


, a couple of ratchet claws


40


A and


40


B which are spaced apart from each other by an angle of 180 degrees and enabled respectively to swing, a couple of compressing coil springs


50


functioning respectively as an urging member for urging the couple of ratchet claws


40


A and


40


B to outwardly turn in the radial direction, and a short cylindrical claw-receiving portion


60


which is projected from one of the sidewalls of the spiral spring case


16


facing the rope pulley


20


. The claw-receiving portion


60


is provided with three trapezoidal engaging portions


61


,


62


and


63


which are spaced apart from each other by an angle of a (an angle of 120 degrees in this embodiment) and are depressed inwardly.




The ratchet claws


40


A and


40


B are respectively constituted by a proximal end portion


41


having a semi-cylindrical surface and provided with an oscillating axis


43


which is rotatably fitted in a bearing hole


25




a


formed in the plate portion


25


of the rope pulley


20


and located close to each of a couple of claw-retaining portions


27


A and


27


B, and by an arm portion


42


extended from the proximal end


41


and having an inwardly bent distal end


41




a


. By the way, the semi-cylindrical surface of the proximal end portion


41


is designed to be slidably contacted with the claw-retaining portion


27


A or


27


B. A locking pin


44


is insertedly attached to the distal end portion of the oscillating axis


43


.




Between the arm portions


42


and a pair of the spring retaining portions


28


A and


28


B of the cylindrical boss portion


26


of the rope pulley


20


, there are interposed a pair of the compressing coil springs


50


each functioning as an urging member for always urging the ratchet claws


40


A and


40


B so as to outwardly turn in the radial direction, thereby enabling the bent distal end portion


41




a


to be pressed against the claw-receiving portion


60


of the spiral spring case


16


, whereby the bent distal end portions


41




a


are permitted to be engaged, in a proper posture, with the engaging portions


61


,


62


and


63


of the claw-receiving portion


60


.




In this case, one end portion


51


of each of the compressing coil springs


50


is inserted into a disengagement-preventing recessed portion


46


which is provided at the distal end of the arm portion


42


of each of the ratchet claws


40


A and


40


B, and at the same time, the one end portion


51


of each of the compressing coil springs


50


is externally fitted over a disengagement-preventing protruded portion


47


which is projected inside the recessed portion


46


. On the other hand, the other end portion


52


of each of the compressing coil springs


50


is bent in the form of hook so as to be introduced into and engaged with a hanging hole formed in the rope reel


20


.




The driven member


7


is constituted by the interlocking pulley


35


, and a centrifugal ratchet mechanism


30


. As clearly seen from the

FIG. 7

, the centrifugal ratchet mechanism


30


comprises a pair of power transmission engaging protrusions


31


which are projected from one of the sidewalls of the actuating pulley


17


facing the engine


1


, and the interlocking pulley


35


which is anchored to the one end


2




a


of the crankshaft


2


. A couple of starting claws


36


for instance are swingably supported by the interlocking pulley


35


. These starting claws


36


are generally urged to turn inward (toward the rotational axial line O) by means of biased spring (not shown), thereby enabling these starting claws


36


to be engaged with the power transmission engaging protrusions


31


. However, when the internal combustion engine


1


is started, these starting claws


36


are caused to outwardly turn radially due to the centrifugal force generated by the rotation of the interlocking pulley


35


that has been driven by the crankshaft


2


, the aforementioned engagement is enabled to be automatically disengaged.




In the case of the recoil starter


5


according to this embodiment which is constructed as explained above, when the recoil rope


21


(or the recoil handle


22


) is manually pulled, the rope pulley


20


is caused to revolve in clockwise in

FIG. 3

(in the direction of R), whereby a couple of the ratchet claws


40


A and


40


B (which are spaced apart from each other by an angle of 180 degrees) are enabled to rotate integral with the rope pulley


20


. When this couple of ratchet claws


40


A and


40


B are started to rotate, one of the ratchet claws, e.g. the ratchet claw


40


A is permitted to contact with one of three engaging portions


61


,


62


and


63


(spaced apart by an angle of 120 degrees [=α]) that have been provided in the spiral spring case


16


, e.g. with the engaging portion


61


as shown in FIG.


3


(A). On this occasion, the other ratchet claw


40


B is positioned at a place which is spaced away by a predetermined angle β (180°−120°=60°) from the other two engaging portions


62


and


63


out of three engaging portions


61


,


62


and


63


.




In this case, since the aforementioned other ratchet claw


40


B is positioned away from the engaging portions


61


,


62


and


63


, the ratchet claw


40


B is kept in a proper state where the bent distal end portion


41




a


is pressed onto the claw-receiving portion


60


provided in the spiral spring case


16


due to the urging force of the compressing coil spring


50


so as to enable the bent distal end portion


41




a


to be properly engaged with the engaging portions


61


,


62


and


63


.




In this case, according to the conventional structure, when one of the ratchet claws, e.g. the ratchet claw


40


A rides over the engaging portion


61


without properly engaging with the engaging portion


61


(as shown by a phantom line in FIG.


3


(A)), the ratchet claws are permitted to ride over the engaging portion one after another, thereby generating a lot of loss in the pulling operation of the rope. Whereas, according to this embodiment, even if one of the ratchet claws, e.g. the ratchet claw


40


A rides over the engaging portion


61


, the other ratchet claw


40


B is enabled, under a proper state, to be immediately contacted with the engaging portion


62


as soon as the rope reel


20


is slightly rotated as shown in FIG.


3


(B), thereby enabling the rotation (or torque) of the rope reel


20


to be reliably transmitted to the spiral spring case


16


.




Therefore, it is possible, with the recoil starter


5


of this embodiment, to suppress the generation of loss in the pulling operation of the recoil rope, to prevent the pulling operation of recoil rope from becoming vacant, and to obtain a smooth pulling feeling of the recoil rope.




Further, since the compressing coil spring


50


is employed as an urging member with one end portion


52


thereof being formed into a hook-like configuration so as to enable it to be secured to the rope reel


20


, the urging member can be prevented from being easily disengaged from the rope reel


20


, thereby improving the reliability of the recoil starter.




When the operation of pulling the rope


21


is performed in this manner, the rotation of the driving member


6


can be transmitted, via the spiral spring mechanism


15


and the interlocking pulley


35


, to the crankshaft


2


of the internal combustion engine


1


.




In this case, during the first-half driving process (until the piston of the internal combustion engine


1


reaches to the top dead center) in the operation of pulling the recoil rope


21


(recoiling operation), it is possible to derive a buffering effect from the spiral spring mechanism


15


, and at the same time, to accumulate the drawing force of the recoiling rope


21


in a spiral spring mechanism


15


, and during the latter-half driving process, the driving 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 by the recoiling rope


21


in the latter-half driving process to thereby generate a resultant force, the energy of which being sufficiently large enough to overcome the load of the compression of the internal combustion engine


1


, thus providing a sufficient energy for starting the internal combustion engine


1


. As a result, it is possible to minimize a fluctuation in pulling force of rope so as to make smooth the rope-pulling operation, thus enabling even a person having a weak physical strength to easily start the engine (for more details, see Japanese Patent Application No. H11-238642).




Further, in the case of the recoil starter


5


according to this embodiment, since it is constructed such that part of the second turn N


2


is closely contacted with the first turn N


1


at the inner circumferentially wound portion Mi of the spiral spring


18


, that the internal hook end


18




b


is displaced as mentioned above, and that the specifications of the spiral spring


18


and the spiral spring mechanism


15


are designed as explained above, the interlocking between the spiral spring mechanism


15


and the internal combustion engine


1


can be disengaged from each other after the start-up of the internal combustion engine due to the free releasing effects to be obtained from the centrifugal ratchet mechanism


30


mounted on the driven member


7


, thereby rendering the spiral spring mechanism


15


into a free state. In this case, even if the spiral spring


18


is excessively kicked back in the unwinding direction (releasing direction) thereof due to the inertia on this occasion even after the spiral spring


18


has been completely unwound, this kick-back stress to be repeated by the effects of rewinding-unwinding on this occasion can be received by the entire body of the inner circumferentially wound portion Mi, thereby making it possible to suppress the generation of a concentration of the stress in the vicinity of the internal hook end


18




b


of the spiral spring


18


.




As a result, the generation of settling or breakage of the spiral spring


18


can be prohibited, thereby making it possible to improve the durability of the spiral spring


18


, and at the same time, the internal hook end


18




b


of the spiral spring


18


can be prevented from being easily disengaged from the core portion


17


C provided at the actuating pulley


17


of the spiral spring mechanism


15


, thereby further improving the reliability of the recoil starter.




While one embodiment of the present invention has been explained in detail, it will be understood that the construction of the device can be varied without departing from the spirit and scope of the invention.




As clearly seen from the above explanation, it is possible, according to the present invention, to provide a recoil starter having a spiral spring mechanism interposed, as a buffering/power-accumulating means, between a driving member comprising a rope reel which is designed to be rotated by the pulling of a recoil rope, and a driven member to which the torque of the driving member is transmitted, the recoil starter being characterized in that it is capable of inhibiting the generation of settling and bending in the spiral spring of the spiral spring mechanism, thereby making it possible not only to improve the durability of the spiral spring, but also to prevent the internal hook end of the spiral spring from being easily disengaged from the core portion of the actuating pulley of spiral spring mechanism. It is also possible, according to the present invention, to provide a spiral spring which is excellent in durability and therefore is suited for use in the recoil starter, etc.



Claims
  • 1. A recoil starter which comprises:a driving member (6) having a rope reel (20) around which a recoil rope (21) is wound to thereby enable said rope reel (20) to be rotated by pulling said recoil rope (21); a driven member (7) to which the torque of said driving member (6) is transmitted; and a spiral spring mechanism (15) interdisposed, as a buffering/power-accumulating means, between said driving member (6) and said driven member (7); wherein said buffering/power-accumulating means (15) is enabled, during the driving process by said driving member (6), to accumulate the power supplied through the driving process while alleviating any impact to said driven member (7), the accumulated power being subsequently employed to drive said driven member (7), and wherein said spiral spring mechanism (15) is rendered free after the start-up of an internal combustion engine (1); said recoil starter being characterized in that said spiral spring mechanism (15) comprises a spiral spring case (16) placed close to said driving member (6), an actuating pulley (17) placed close to said driven member (7), a spiral spring (18) interposed between said spiral spring case (16) and said actuating pulley (17), and means (19) for rotating said spiral spring case only unidirectionally, wherein an outer end portion (18a) of said spiral spring (18) and an inner end portion (18b) of said spiral spring (18) are fastened to said spiral spring case (16) and said actuating pulley (17), respectively, wherein said spiral spring (18) comprises an outer circumferential wound portion (Mo) where a predetermined number of turns of the outer circumferentially wound portion (Mo) of the spiral spring (18) are closely contacted with each other under a freely released condition of the spiral spring (18), and an inner circumferential would portion (Mi) which is constituted by at least one turn of said inner circumferentially wound portion (Mi) of said spiral spring (18), wherein a clearance (S) is provided between said outer circumferential wound portion (Mo) and said inner circumferential would portion (Mi).
  • 2. The recoil starter according to claim 1, wherein said means for rotating said spiral spring case (16) only unidirectionally is preferably constituted by a one-way clutch (19).
  • 3. The recoil starter according to claim 1, wherein said outer circumferential wound portion (Mo) is constituted by a third turn (N3) and the following turns successive to said third turn (N3), and said inner circumferential wound portion (Mi) is constituted by a first turn (N1) and at least a portion of the second turn (N2) which is closely contacted with said first turn (N1).
  • 4. The recoil starter according to claim 1, wherein said actuating pulley (17) is provided with a core portion (17A) around which said spiral spring (18) is wound; said spiral spring (18) is provided, at an inner end portion thereof, with a C-shaped or ring-shaped internal hook end (18b); and said core portion is provided with an inner end-holding portion (17C) into which said internal hook end (18b) is adapted to be inserted and held therein.
  • 5. The recoil starter according to claim 1, wherein said spiral spring (18) is provided, at an outer end portion thereof, with an external hook end (18a); and said spiral spring case (16) is provided, at an outer circumferential wall thereof with an outer end-holding portion (16C) with which said external hook end (18a) is adapted to be engaged.
  • 6. The recoil starter according to claim 1, wherein said inner end portion (18b) of said spiral spring (18) is positioned, under a freely released condition of said spiral spring (18), at a position which is displaced from the location of said outer end portion (18a) of said spiral spring (18) by a predetermined angle (γ) toward one direction (L) which is opposite to a driving direction (R).
  • 7. The recoil starter according to claim 1, wherein the rotational axial line (O) of said spiral spring mechanism (15) is preferably displaced from the proper center (K) of said spiral spring (18) by a predetermined distance (e) toward said outer end portion (18a) of said spiral spring (18).
  • 8. The recoil starter according to claim 4, wherein the outer diameter of said core portion (17A) of actuating pulley (17) is made almost identical with the effective inner diameter (Di) of the first turn (N1) of said spiral spring (18), and the effective outer diameter (Do) of said spiral spring (18) under the freely released condition thereof is made almost identical with the effective inner diameter of said spiral spring case (16).
  • 9. The recoil starter according to claim 4, wherein said effective inner diameter (Di) of said first turn (N1) of said spiral spring (18) and the effective outer diameter of said core portion (17A) are set to 25 mm or more.
  • 10. The recoil starter according to claim 1, wherein said spiral spring (18) is formed of a stainless steel sheet having a thickness of 0.5 to 0.7 mm.
  • 11. The recoil starter according to claim 1, wherein the inner circumferential wound portion of said spiral spring (18) has been subjected to an annealing treatment.
  • 12. The recoil starter according to claim 1, wherein said driving member (6) is provided with a recoiling urging means (23) for reversely revolving said rope reel (20) so as to rewind said recoil rope (21), and also with a recoil ratchet mechanism (40) for transmitting the torque of said rope reel (20) to said spiral spring case (16).
  • 13. The recoil starter according to claim 1, wherein said driven member (7) is provided with an interlocking pulley (35) having a power transmission mechanism (30) through which said driven member (7) is enabled to interlockingly coupled with said driving member (6).
  • 14. The recoil starter according to claim 13, wherein said power transmission mechanism is constituted by a centrifugal ratchet mechanism (30).
Priority Claims (1)
Number Date Country Kind
2001-254025 Aug 2001 JP
US Referenced Citations (3)
Number Name Date Kind
4480605 Bloemers Nov 1984 A
5287832 Uhl Feb 1994 A
6508220 Akaike et al. Jan 2003 B1