Title of Invention	ENGINE STARTER
Abstract	An engine starter in which one of a front housing and a yoke has a projection, and the other of the front housing and the yoke have engaging portions engage the projection to prevent a rotative motion of the yoke. Thereby, a breakdown of through bolts, which is used for fixing the yoke to the foront housing, by a shearing force is prevented. PRICE :THIRTY RUPEES

Full Text

This invention relates to an engine starter used for an automotive engine or the like-DESCRIPTION OF THE RELATED ART Fig. 7 is a cross sectional view of a conventional planetary speed-reduction engine starter such as disclosed in Japanese Patent Publication No.5-28380. In this figure, an armature 1 has a shaft 2 provided with an armature gear 2a, an armature core 3 fixed to the shaft 2, and armature coils 4 fixed to the armature core 3. Fixed on the inner peripheral surface of a cylindrical yoke 5 surrounding the armature 1 are magnets 6 which face against the outer peripheral surface of the armature 1. A motor 7 has the armature 1, the yoke and the magnets 6. Further, Fig. 8 is a cross sectional view of the yoke 5 of Fig. 7. The yoke 5 has a bottom portion having a hole for receiving the shaft 2 of the armature 1 therein. The motor 7 is connected to an output shaft 9 through a planetary reduction mechanism 8. An overrunning clutch 10 and a pinion 11 capable of reciprocating motion on the output shaft 9 such that it engages a ring gear (not illustrated) of the engine are provided. The overrunning clutch 10 is connected to a plunger of an electromagnetic switch 13 by means of a lever 12. The yoke 5 and the electromagnetic switch 13 are attached to a front housing 15. The planetary reduction mechanism 8, the output shaft 9, the overrunning clutch 10, the pinion 11 and the lever 12 are disposed in the front housing 15. A rear housing 16 is attached to a rear end (the left end in the figure) of the yoke 5. Further, the yoke 5 is fixed to the front housing 15 by means of through bolts 17. Description will now be made of the operation. When the electromagnetic switch 13 is turned ON, the plunger 14 moves toward the left in the figure, causing currents to flow into the motor 7. The lever 12, which is mechanically engaged to the plunger 14, rocks and causes the overrunning clutch 10 and the pinion 11 to slide toward the right in the figure along the output shaft 10. Thus, the pinion 11 engages with the ring gear of the engine. The rotation of the motor 7 is transmitted to the pinion 11 via the planetary reduction mechanism 8, the output shaft 9 and the overrunning clutch 10, thereby starting the engine. When the electromagnetic switch 13 is turned OFF after the engine is started, the plunger 14 is moved back to its original position and the currents flow to the'motor 7 is blocked. Further, the overrunning clutch 10 is also moved back to its original position by means of the lever 12, which is accompanied by the pinion 11 separating from the ring gear. In the conventional engine starter with the above-described construction, the yoke 5 is fixed to the front housing 15 by only means of the through bolts 17, therefore the vibration of the engine causes the yoke 5 to move toward the rotative direction while the through bolts 17 are inclined. Further, the rotative motion of the yoke 5 causes the through bolts 17 to be"broken if circumstances require. SUMMARY OF THE INVENTION Accordingly, an object of the this invention is to provide an engine starter which can prevent a rotative motion of a yoke and a breakdown of a through bolt which is used for fixing the yoke to a front housing. In order to achieve the above object, there is provided an engine starter comprising: a front housing; a I motor including a cylindrical yoke attached to the front housing by means of a through bolt, magnets fixed on the inner peripheral surface of the yoke, and an armature disposed in the yoke; an output shaft which is disposed in the front housing and which rotates as a driving force of the motor is transmitted; a pinion which is capable of engaging with and disengaging from a ring gear of an engine and which rotates as the output shaft rotates; and an electromagnetic switch which is used to cause the pinion to engage with and disengage from the ring gear and also to energize and deenergize the motor; wherein one of the front housing and the yoke has a projection, and the other of the front housing and the yoke have engaging portions which engage said projection to prevent a rotative motion of said yoke relative to the front housing. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a partial sectional view of an engine starter as a first embodiment of the invention; Fig. 2 is a cross sectional view of a yoke of Fig. 1; Fig. 3 is a front view of the yoke of Fig. 2; Fig. 4 is a cross sectional view of a front housing along line IV-IV of Fig. 1; Fig. 5 is a front view of a yoke of an engine starter as a second embodiment of the invention; Fig. 6 is a partial sectional view of an front housing as the second embodiment; Fig. 7 is a cross sectional view of an example of a conventional engine starter; Fig. 8 is a cross sectional view of a yoke of Fig. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Fig. 1 is a partial sectional view of an engine starter as a first embodiment of the invention. Fig. 2 is a cross sectional view of a yoke of Fig. 1. Fig. 3 is a front view of the yoke of Fig. 2. Fig. 4 is a cross sectional view of a front housing along line IV-IV of Fig. 1. In these figures, a cylindrical yoke 21 has a projection 21a formed by punch pressing process at its end of a front housing 22 side, that is, the bottom portion. The front housing 22 made of metal has a dent 22a for inserting the projection 21a. The projection 21a engages both side walls of the dent 22a, those are, engaging portions 22b, 22c. The major members constituting the engine starter are almost the same as those of Fig. 7. In this engine starter, since the projection 21a of the yoke 21 engages the engaging portions 22b, 22c of the front housing 22, the rotative motion of the yoke 21 is prevented and the yoke 21 is positioned exactly. Since the force toward the direction of the rotation is transmitted from the projection 21a t^ the engaging portions 22b, 22c, a breakdown of the through bolts 17 (Fig. 7) by the shearing force is prevented. Further, since the projection 21a is formed by punch pressing a part of the yoke 21, the increasing of the number of parts is prevented and the cost for the positioning of the yoke 21 goes down. Second Embodiment While one projection 21a is provided in the above first embodiment, it is possible that two projections 21a are provided as shown in Fig. 5. Fig, 6 is a sectional view showing the state of the arrangement of the engaging portions 22b, 22c in this second embodiment. Further, the projection 21a can be provided at anywhere on the circumference of the yoke 21 and at more than three parts of the yoke 21. Furthermore, while the projection 21a is provided at the yoke 21 and the engaging portions 22b, 22c are provided at the front housing 22, it is possible that the projection is provided at the front housing and the engaging portions is provided at the yoke. Moreover, while the above embodiments have been described with respect to the planetary speed-reduction engine starter, this invention may also be applied to various types of the engine starter. WE CLAIM: 1. An engine starter, comprising : a front housing; a motor having a cylindrical yoke attached to said front housing by means of a through bolt, magnets fixed on the inner peripheral surface of said yoke, and an armature disposed in said yoke; an output shaft disposed in said front housing and which rotates as a driving force of said motor Is transmitted; a pinion capable of engaging with and disengaging from a ring gear of an engine and which rotates as said output shaft rotates; and an electromagnetic switch to cause said pinion to engage with and disengage from said ring gear and also to energize and deenergize said motor, wherein one of said front housing and said yoke has a projection, and the other of said front housing and said yoke have engaging portions which engage said projection to prevent a rotative motion of said yoke relative to said front housing. 2. The engine starter according to claim I, wherein said cylindrical yoke has a bottom portion having a hole for receiving a shaft of said armature therein, and said projection is formed by punch pressing process at said bottom portion. 3. The engine starter according to claim 2, wherein said yoke has a plurality of said projection. 4. The engine starter according to claim 1, wherein said motor is connected to said output shaft through a planetary reduction mechanism, and an overrunning clutch and said pinion capable of reciprocating motion on said output shaft are provided on said output shaft. 5. An engine starter, substantially as herein described with reference to figures 1-6 of the accompanying drawings. DUPL'Q^TE

Documents:

1113-mas-1995 abstract.jpg

1113-mas-1995 abstract.pdf

1113-mas-1995 claims.pdf

1113-mas-1995 correspondence -others.pdf

1113-mas-1995 correspondence -po.pdf

1113-mas-1995 description (complete).pdf

1113-mas-1995 drawings.pdf

1113-mas-1995 form -1.pdf

1113-mas-1995 form -26.pdf

1113-mas-1995 form -4.pdf

1113-mas-1995 petition.pdf