Title of Invention

AN INTERNAL COMBUSTION ENGINE STARTER

Abstract

The present invention relates to an internal combustion engine starter which ensures excellent dust-proof and water-proof effects and allows the reduction of its overall length. The starter comprises an armature shaft having a bearing supported section and a step section, a front bracket for supporting the bearing supported section, a commutator composed of a columnar section fixed to the armature shaft and a cylindrical section protruding from the columnar section and defining a gap with respect to the armature shaft, and a rear bracket having a depressed cylindrical section extending to the inside of the cylindrical section of the commutator. A washer is mounted on the bearing supported section between the step section and an inner portion of the front bracket for receiving a forward stress of the armature shaft and for regulating a forward sliding movement of the armature shaft. A regulating member is placed between an end portion of the depressed cylindrical section and at least one of the armature shaft and the commutator and made to receive a backward stress of the armature shaft through at least one of the armature shaft and the commutator, thereby regulating a backward sliding movement of the armature shaft.

Full Text

The present invention relates to an internal combustion engine starter for starting an internal combustion engine, and more particularly to a starter superior in dust-proof and water-proof effects. Description of the Related Art Fig. 4 is a cross-sectional view showing a prior art starter. In Fig. 4, the starter has a DC motor 1 at its central portion. The front section of the DC motor 1 is covered with a front bracket 2 while the rear section thereof is covered with a rear bracket 3. An armature shaft 5 penetrates the center of an armature 4 of the DC motor 1 and its front end portion 5a is supported by a sleeve bearing 5 fitted in a front end portion of the front bracket 2. In addition, the rear end portion of the armature shaft 5 is supported by a sleeve bearing 8 fitted in an inner circumferential surface of a depressed cylindrical section 3a of the rear bracket 3 which gets in s recess portion 7a made in an inner circumferential surface of a commutator 7. Further, the rear end portion of the armature shaft 5 undergoes the regulation on its axial movement by means of a washer 9 inserted into between the rear bracket 3 and an end surface of the commutator 7 and a retaining ring 11 fitted in a recess groove 5b made in the rear end portion of the armature shaft 5 to hold a washer 10 inserted into an outer surface of the rear bracket 3. A brush holder 12 is located inside the rear bracket 3, and the energization is achievable with a brush being brought into contact with the commutator 7. An overrunning clutch 13 is spline-engaged with the armature shaft 5 to slide forwardly, i.e., in the right-hand direction in Fig. 4, on the shaft in accordance with the rotation of a shift lever 14 so that a pinion 15 formed integrally with its end portion is geared with a ring gear of an internal combustion engine (not shown). A magneto switch 16 is screwed to the front bracket 2 and energized to absorb a plunger 17, thereby causing the rotation of the shift lever 14. A description will be made hereinbelow of an operation of the starter thus constructed. In response to the closure of a key switch of an internal combustion i engine (not shown), the energization to the magneto switch 16 takes place so that the plunger 17 is absorbed in the left-hand direction in Fig. 4 t£ make the overrunning clutch 13 slide in the right-hand direction in the same illustration, thereby i leading to the engagement between the pinion 15 and the ring gear (not shown). At this operation, the DC motor 1 is energized through the magneto switch 16 so that the armature 4 generates a rotating force (torque). This rotating force i^ transferred through a spline-engaging portion 5c of the armature shaft 5 to the overrunning clutch 13 and further to the pinion 15 assuming a one-way engaging condition, so that the ring gear (not shown) rotates to start the internal combustion engine. After the starting of the internal combustion engine, the energization to the magneto switch 16 is stopped so that the rotation of the DC motor 1 stops and the overrunning clutch 13 returns to the condition as illustrated. At the time of the aforesaid engagement or return, i.e., when the overrunning clutch 13 moves forward or backward with respect to the DC motor 1, a thrust stress takes place as a reaction force in the armature shaft 5. Of this thrust stress, the component applied to the left side (rear side) in the illustration comes through the commutator 7 and a washer 9 contacting with the end surface of the commutator 7 to the rear bracket 3, which receives the stress component. On the other hand, of the thrust stress, the component applied to the right side (front side) comes through the retaining ring 11 fitted in the recess groove 5b and the washer 10 contacting with the end surface of the rear bracket 3 to the rear bracket 3, which ! receives the stress component. Incidentally, the aforesaid thrust stress also occurs in connection with the vibration exciting force of the internal combustion engine, a similar pressure receiving force works to regulate the axial movement of the armature !4. ! In the case of the prior armature 4 movement regulating structure thus arranged, the thrust stress receiving function is taken in a manner that the rear end portion of the armature shaft 5 is made to protrude from the end surface of the rear , bracket 3 and the recess groove 5b is formed to accept the retaining ring 11. | However, this construction creates a problem in complication and increase in size of I the apparatus. In addition, the rear end portion of the armature shaft 5 is exposed to the external space, and dust and liquid tend to get therein through the gaps du^ to the washer 9 and the retaining ring 11, which deteriorates the apparatus reliability. SUMMARY OF THE INVENTION Accordingly, the present invention has been developed with a view to eliminating these problems, and it is an object of the present invention to provide a starter which is superior in dust-proof and water-proof effects and which ensures a hi9h reliabiiity- an internal combustion In accordance with an aspect of the present invention, / starter comprises an armature shaft having, at its front end portion, a bearing supported section with a smaller diameter and having a step section adjacent to the bearing supported section, a front bracket for supporting the bearing supported section through a bearing, a washer mounted on the bearing supported section between the step section and an inner portion of the front bracket for receiving a stress of the armature shaft in a front side direction which works through the step section by coming into contact with the inner portion and for regulating a sliding movement of the armature shaft in the front side direction, a commutator fitted over a rear end portion of the armature shaft and composed of a columnar section fixedly secured to the armature shaft and a cylindrical section protruding from a rear end portion of the columnar section and defining a gap with respect to the armature shaft, a rear bracket having a depressed cylindrical section formed to extend to the inside of the cylindrical section of the commutator, a sleeve bearing located between an inner circumference of the depressed cylindrical section and an outer circumference of the rear end portion of the armature shaft to support the armature shaft, a regulating member placed between an end portion of the depressed cylindrical section of the rear bracket and at least one of the armature shaft and the commutator for receiving a stress of the armature shaft in a rear side direction which works through at least one coming of the armature shaft and the commutator by / into contact with the end portion of the depressed cylindrical section and for regulating a sliding movement of the armature shaft in the rear side direction, and a cap fitted in an inner circumference of the depressed cylindrical section of the rear bracket to close the rear end portion of the armature shaft. In the starter according to another aspect of this invention, the regi Hating member is a washer provided between the end portion of the depressed cylindrical section of the rear bracket and a step section made at a rear end portion of the armature shaft. In the starter according to a different aspect of this invention, the regulating member is a washer provided between the end portion of the depressed cylindrical section of the rear bracket and an end portion of an inn^r wall of the cylindrical section of the commutator. In the starter according to a different aspect of this invention, the regulating member is a cylindrical regulating member placed between the end portion of the depressed cylindrical section of the rear bracket and a rear end portion of the commutator. In the starter according to a different aspect of this invention, the washer comprises a plurality of washers piled up corresponding to a dimension of a gap between the end portion of the depressed cylindrical section of the rear bracket and the step section made at the rear end portion of the armature shaft. In the starter according to a different aspect of this invention, the washer comprises a plurality of washers piled up corresponding to a dimension of a gap between the end portion of the depressed cylindrical section of the rear bracket and the end portion of the inner wall of the cylindrical section of the commutator. In the starter according to a different aspect of this invention, the cap is fitted under pressure in the inner circumference of the depressed cylindrical section of the rear bracket. In the starter according to a different aspect of this invention, the cap has microscopic holes made therein. BRIEF DESCRIPTION OF THE DRAWINGS The object and features of the present invention will become more readily apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings in which: Fig. 1 is a cross-sectional view showing a starter according to a first embodiment of the present invention; Fig. 2 is an enlarged view showing the vicinity of a depressed cylindrical section of a rear bracket; Fig. 3 is a cross-sectional illustration of a principal portion, showing a starter according to a second embodiment of this invention, and Fig. 4 is a cross-sectional view showing a prior/starter. DETAILED DESCRIPTION OF THE INVENTION First Embodiment Fig. 1 is a cross-sectional view showing a starter according to a first embodiment, and Fig. 2 is an enlarged illustration of the vicinity of a depressed cylindrical section of a rear bracket. In Fig. 1, the starter includes a DC motor 18 at its central portion. The front section of the DC motor 18 is covered with a front bracket 21 while the rear section thereof is covered with a rear bracket 3. An armature 19 has an armature shaft 20 penetrating its central section. The front end portion of the armature shaft 20 is machined to have a step configuration to produce a step section 20b and a bearing supported section 20a formed to have a smaller diameter. The bearing supported section 20a is loosely supported by a sleeve bearing 22 fitted in the front end portion of the front bracket 21. Further, a washer 23 is fitted over the bearing supported section 20a. One surface of the washer 23 is placed in a contact relation to the step section 20b whole the other surface thereof is located in a contact relation to a recess portion 21a made in an inner circumferential surface of the front end portion of the front bracket 21. The rear end portion of the armature shaft is step-machined in a similar way to produce a step section and a bearing supported section 20e having a smaller diameter. In addition, the rear end portion of the armature shaft 20 is provided with a commutator 24 which serves as one of the components of the armature 19. The commutator 24 is composed of a columnar section 24a fixedly secured to the rear end portion of the armature shaft 20 and a cylindrical section 24b extending backwardly from the rear end of the columnar section 24a to define a gap with respect to the armature shaft 20. The rear end surface of the columnar section 24a, i.e., a bottom surface 24c of a recess portion formed by the cylindrical section 24b, is made to be equal in plane to the step section 20c. A depressed cylindrical section i 3a is formed at a generally central portion of the rear bracket 3 so that a hole edge ; is depressed toward its interior, and extends within the cylindrical section 24b of the commutator 24. A sleeve bearing 8 is fitted in the inner circumferential surface of the depressed cylindrical section 3a of the rear bracket 3, and the bearing supported section 20e of the rear end portion of the armature shaft 20 is loosely supported by i this sleeve bearing 8. A washer 25 acting as a regulating member and a thrust gap; adjusting washer 26 are interposed between the tip portion of the depressed cylindrical section 3a of the rear bracket 3 and the step section 20c of the armature; shaft 20, i.e., the bottom surface 24c of the commutator 24. Furthermore, a helical spline 20d is rolling-formed or\ the outer circumferencial surface of the armature shaft 20. This helical spline 20d is spline-engaged with an overrunning clutch 13, and the overrunning clutch; 13 is made to be slidable on the armature shaft 20 in the right- and left-hand directions. Still further, a cap 27 manufactured by press-forming an iron plate is fitted under pressure in the inner circumference of the depressed cylindrical section 3a of i the rear bracket 3 to completely seal the rear end portion of the armature shaft 20. A brush holder 12 is located inside the rear bracket 3 and the energization is made by the contact of a brush with the commutator 7. The overrunning clutch 13 is spline-engaged with the armature shaft 20 and is made to slide on the shaft in the front side direction, i.e., in the right-hand direction in Fig. 4, by the rotation of a shaft. lever 14, so that a pinion 15 formed integrally with its one end portion is geared with a ring gear of an internal combustion engine (not shown). A magneto switch 16 is screwed to the front bracket 21 and absorbs a plunger 17 in response to energization, thus rotationally moving the shift lever 14. A description will be made hereinbelow of an operation of the starter thus constructed. In response to the closure of a key switch of an internal combustion engine (not shown), the magneto switch 16 is energized to absorb the plunger 17 in the left-hand direction in Fig. 1, so that the shift lever rotates and the overrunning clutch 13 engaged with its other end portion slides in the right-hand direction in Fig. 1 to make the pinion 15 geared with the ring gear (not shown). At the aforementioned operation, the DC motor 18 is energized through the magneto switch 16 and the armature 19 generates a rotating force. This rotating force is transferred through the helical spline 20d of the armature shaft 20 to the overrunning clutch 13 and then to the one-way engaged pinion 15, whereupon the internal combustion engine starts due to the rotation of the ring gear (not shown). After the starting of the internal combustion engine, the energization to the magneto switch 16 stops and the rotation of the DC motor 18 also stops, and even the overrunning clutch 13 returns to the condition as illustrated. At the engagement or returning, that is, when the overrunning clutch 13 ■ moves forwardly or backwardly with respect to the DC motor 1, a thrust stress occurs : as a reaction force in the armature shaft 20. Of this thrust stress, a component applied in the right-hand direction (forward direction) comes through the step section 20b and the washer 23 to the recess portion 21a of the front bracket 21 which , receives the stress component. On the other hand, the component applied in the ! left-hand direction (backward direction) is transferred through the bottom surface 24c ; of the commutator 24 and the adjusting washer 26 contacting with the step section 20c of the armature shaft 20 to the washer 25 contacting with the depressed ' cylindrical section 3a of the rear bracket 3, with the washer receiving the stress component. Incidentally, the aforesaid thrust stress also occurs in connection with the vibration exciting force of the internal combustion engine, a similar pressure receiving force works to regulate the axial movement of the armature 4. In the starter thus constructed, the bearing supported section 20e of the rear end portion of the armature shaft 20 is loosely supported by the sleeve bearing 8 fitted in the inner circumferential surface of the depressed cylindrical siection 3a of the rear bracket 3, and hence the armature shaft 20 is supported by the rear bracket 3 with a high accuracy like the conventional construction. In addition, since the rear end portion of the armature shaft 20 does not protrude from the rear bracket 3, it is possible to shorten the overall length of the starter. Moreover, the installation of the cap 27 permits exhibiting the excellent functions in the dust-proof and water-proof effects, which provides a high reliability irrespective of a long use. Although in this embodiment two washers serving as the washer 25 and the thrust gap adjusting washer 26 are put between the tip portion of the depressed cylindrical section 3a of the rear bracket 3 and the step section 20c of the armature shaft 20 or the bottom surface 24c of the commutator 24, the number of these washers is not limited to two but increases in accordance with the gap defined therebetween. Further, although in this embodiment the adjusting washer 26 is placed into contact with both the step section 20c of the armature shaft 20 and bottom surface 24c of the commutator 24 on the right side in Fig. 2, it is not always required to be placed into contact with both, and if being brought into contact with one of them, the thrust stresses in the right- and left- hand direction are receivable, ! thus producing the same effects. I Moreover, for example, if the step section 20c of the armature shaft 20 is i set to be larger and the adjusting washer 26 is placed to come into contact with only the step section 20c so that only the step section 20c receives the right and left thrust stresses, the bottom surface 24c of the commutator 24 becomes unnecessary, and in this case, the formation of the cylindrical section 24b is not always necessary. On the contrary, if the gap defined between the cylindrical section 24b of the commutator: 24 and the armature shaft 20 is set to be larger and the adjusting washer 26 is! i i located to come into contact with only the bottom surface 24c so that the right and; I left thrust stresses are received by only the bottom surface 24c of the commutator 24,! the step section 20c of the armature shaft 20 is not always necessary. ' In addition, in place of the sleeve bearing 22 fitted in the front end portion of the front bracket 21, it is also possible to use a different bearing such ks a needle bearing. The aforesaid cap 27 is not limited to the iron plate but dan also be manufactured by the formation of a resin, for example. Moreover, the cfip 27 is not limited to having the complete sealing function but can also have rtnicroscopic through-holes serving as air holes. The fitting method of the cap 27 is not limited to being fitted under pressure, but the welding and the thermal caulking techniques are also acceptable. i Second Embodiment Fig. 3 is an enlarged illustration of the vicinity of the depressed cylindrical section of the rear bracket according to another embodiment of this invention. In Fig. 3, a cylindrical regulating member 28 having a generally cylindrical configuration is coaxially placed between the cylindrical section 24b of the commutator 24 and the depressed cylindrical section 3a of the rear bracket 3. The cylindrical regulating member 28 is manufactured by the press formation of an iron plate and has a generally cylindrical configuration having a diameter smaller than that of the cylindrical section 24b of the commutator 24, with the entire circumferential edge of its armature 19 side end portion (the right side in Fig. 3) being vertically bent to the central axis to come into contact with the tip portion of the depressed cylindrical section 3a of the rear bracket 3 while the entire circumferential edge of the other end portion being bent outwardly to come into contact with the rear end surface 24d of the commutator 24. The other arrangements are the same as those of the first embodiment. In the starter thus arranged, of a thrust stress working on the armature shaft 20( the component applied in the left-hand direction in Fig. 3 (rear direction) is transferred from the rear end surface 24d of the commutator 24 to the tip portion of the depressed cylindrical section 3a of the rear bracket 3 and received by the tip portion of the depressed cylindrical section 3a, which can provide the same effects ; as those in the first embodiment. In addition, even if the gap between the tip portion of the depressed cylindrical section 3a and the commutator 24 or the step section 20c of the armature shaft 20 is large, it is possible to cope with this without increasing the number of parts. Incidentally, if the gap defined between the cylindrical section 24b of the commutator 24 and the armature shaft 20 is set to be large, the step section 20c of the armature shaft 20 is not always necessary. That is, the diameter of the bearing ' supported section 20e can be designed to be equal to that of the armature shaft 20. i With the above-described construction, the armature shaft can be i i supported by the rear bracket with a high accuracy, and since there is.no need for the rear end portion of the armature shaft to protrude from the rear bracket, the entire length of the starter is reducible. In addition, the fitting of the cap allows exhibiting the dust-proof and water-proof effects and hence ensures a hic|h leliability irrespective of a long use. j Furthermore, according to this invention, the regulating member can receive the thrust stress with a simple structure, and the cylindrical regulating member can deal with the case that the gap between the end pdrtion of the depressed cylindrical section and the commutator or the step section at the rear end portion of the armature shaft is large. Moreover, the fitting of the cap is possible with a simple structure. In addition, since the cap has microscopic holes, air can be discharged through the microscopic holes at the fitting of the cap and hence the fitting of the cap becomes easy. It should be understood that the foregoing relates to only preferred embodiments of the present invention, and that it is intended to cover all changes and modifications of the embodiments of the invention herein used for the purpose of the disclosure, which do not constitute departures from the spirit and scope of the invention. WE CLAIM; 1. An internal combustion engine starter comprising: an armature shaft having, at its front end portion, a bearing supported section with a smaller diameter and having a step section adjacent to said bearing supported section; a front bracket for supporting said bearing supported section through a bearing; a washer mounted on said bearing supported section between said step section and an inner portion of said front bracket for receiving a stress of said armature shaft in a front side direction which works through said step section by coming into contact with said inner portion and for regulating a sliding movement of said armature shaft in said front side direction; a commutator fitted over a rear end portion of said armature shaft and composed of a columnar section fixedly secured to said armature shaft and a cylindrical section protruding from a rear end portion of said columnar section and defining a gap with respect to said armature shaft; a rear bracket having a depressed cylindrical section formed to extend to said inside of said cylindrical section of said commutator; a sleeve bearing located between an inner circumference of said depressed cylindrical section and an outer circumference of said rear end portion of said armature shaft to support said armature shaft; a regulating member placed between an end portion of said depressed cylindrical section of said rear bracket and at least one of said armature shaft and said commutator for receiving a stress of said armature shaft in a rear side direction which works through at least one of said armature shaft and said commutator by coming / into contact with said end portion of said depressed cylindrical section and for regulating a sliding movement of said armature shaft in said rear side direction; and a cap fitted in an inner circumference of said depressed cylindrical section of said rear bracket to close said rear end portion of said armature shaft. 2. The starter according to claim 1, wherein said regulating member is a washer provided between said end portion of said depressed cylindrical section of said rear bracket and a step section made at a rear end portion of said armature shaft. 3. The. starter according to claim 1, wherein said regulating member is a washer provided between said end portion of said depressed cylindrical section of said rear bracket and an end portion of an inner wall of said cylindrical section of said commutator. 4. The. starter according to claim 1, wherein said regulating member is a cylindrical regulating member placed between said end portion of said depressed cylindrical section of said rear bracket and a rear end portion of said commutator. 5. Thtf starter according to claim 2, wherein said washer comprises a plurality of washers piled up corresponding to a dimension of a gap between said end portion of said depressed cylindrical section of said rear bracket and said step section made at said rear end portion of said armature shaft. 6. The starter according to claim 3, wherein said washer comprises a plurality of washers piled up corresponding to a dimension of a gap between said end portion of said depressed cylindrical section of said rear bracket and said end portion of said inner wall of said cylindrical section of said commutator. 7. The starter according to claim 1, wherein said cap is fitted under pressure in said inner circumference of said depressed cylindrical section of said rear bracket. 8. The starter according to claim 1, wherein said cap has microscopic holes made therein. 9. An internal combustion engine starter substantially herein as described with reference to Figs. 1 to 3 of the accompanying drawings.

Documents:

1999-mas-1997 abstract duplicate.pdf

1999-mas-1997 claims duplicate.pdf

1999-mas-1997 description (complete) duplicate.pdf

1999-mas-1997 form-4.pdf

1999-mas-1997 petition.pdf

1999-mas-1997- abstract.pdf

1999-mas-1997- claims.pdf

1999-mas-1997- correspondence others.pdf

1999-mas-1997- correspondence po.pdf

1999-mas-1997- description complete.pdf

1999-mas-1997- form 1.pdf

1999-mas-1997- form 26.pdf

1999-mas-1997- form 3.pdf

1999-mas-1997- other documents.pdf