ENGINE STARTER

Abstract: An engine starter (10) includes an electric motor (15) having a hollow rotary shaft (16) for causing a turning force to start an engine, a hollow inner clutch (28) rotatably supported in the hollow rotary shaft (16) through a one-way clutch, a pinion shaft (33) provided with a pinion (33b) which is engaged with a ring gear of the engine, and spline-fitted in the hollow inner clutch (28) to move in the axial direction thereof, an electromagnetic switch (40) attached to one end of the electric motor (15) for turning on or off the electric motor (15), and a moving body (46) which moves in conjunction with the electromagnetic switch (40) to move the pinion shaft (33) in the axial direction thereof to engage the pinion (33b) with the ring gear.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an engine starter, and particularly to an angine starter of a coaxial type for a vehicle. Prior Art FIG. 1 shows a conventional starter 200 for the engine of a vehicle. The starter 200 comprises a DC motor 202, an overrunning clutch mechanism 106 slidably fitted on the extended portion 102a of the rotary shaft 102 of the armature of the DC motor, a front brace 114 serving also as a bearing for the end of the extended portion of the rotary shaft, and a shift lever 117, one end of which is engaged with the plunger rod 207 of an electromagnetic switch 118 provided alongside the DC motor to slide the overrunning clutch mechanism on the extended portion of the rotary shaft and the other end of which is engaged with an annular member 208 attached to the overrunning clutch mechanism. An armature 100 of the DC motor comprises a core 101, the rotary shaft 102 of the armature, a commutator 103 fitted to the rear portion of the rotary shaft, and an armature coil 104 wound on the core and connected to the commutator. A helical spline 105 is provided in the rotary shaft 102 in front of the armature core 101 and fitted with an overrunning clutch 106. Brushes 107 are supported in contact with the commutator 103 by brush holders 108 and secured to a rear brace 109 by bolts 110. A bearing 111 is provided between the rear brace 109 and the rear end portion of the rotary shaft 102. The overrunning clutch 106 includes an outer member 106a, rollers 106b, a pinion 106c, which is engaged with the ring gear of an engine and supported to the rotary shaft 102 by a sleeve bearing 106d fitted on the inside surface of the pinion, and a cover 106e covering the body of the over-running clutch. The pinion 106c is slidable in the axial direction of the rotary shaft 102. A stopper 112 is provided on the rotary shaft 102 so that the pinion 106c comes into contact with the stopper when being moved forward. A sleeve bearing 113 is attached to the inside surface of the front end portion of a front brace 114 and supports the rotary shaft 102 at the front end thereof. A plurality of permanent magnets 116, which function as a field for the armature 100, are secured to the inside surface of a yoke 115 provided to form a magnetic circuit and constitute a casing. The ends of a plastic lever 117 are engaged with the plunger 119 of an electromagnetic switch 118 and the peripheral portion of the overrunning clutch 106. A movable contact 120 is attached to a rod 122 by an electric insulator 121. The rod 122 is inserted in a core 123 so that the rod is slidable back and forth. A fixed contact 124 is secured to a cap 125 made of an electric insulator. A driving coil 126 for moving the plunger 119 is wound on a plastic bobbin 127 and housed in a case 128. A lead wire 129 connects the fixed contact 124 and the corresponding brush 107 to each other. A return spring 130 is provided between the core 123 and the plunger 119. The operation of the conventional engine starter is described from now on. When an ignition switch is closed, the driving coil 126 of the electromagnetic switch 118 is supplied with electricity to move the plunger 119 backward to push the rod 122 backward to bring the movable contact 120 into contact with the fixed contact 124. As a result, electricity is applied to the armature 100 through the fixed contact 124, the lead wire 129 and the brush 107 to rotate the armature. The turning force of the armature 100 is transmitted to the overrunning clutch 106 through the helical spline 105 of the peripheral portion of the rotary shaft 102 to rotate the pinion 106c. Since the plunger 119 is moved backward, the lever 117 is turned counterclockwise to slide the overrunning clutch 106 forward to engage the pinion 106c with the ring gear secured to a flywheel attached to the crankshaft of the engine. Immediately after the engine is started, only the pinion 106c is moved together with the ring gear because of the one-way overrunning action of the overrunning clutch 106 so that the pinion races. When the ignition switch is opened at the end of the starting of the engine, the driving coil 126 is deenergized to return the plunger 119 to the original position thereof by the force of the return spring 130 in the electromagnetic switch 118 and also return the overrunning clutch 106 to the original position thereof. Consequently, the engine starter stops. However, the conventional starter 1 thus constituted has a disadvantage that it needs the shift lever 117 for sliding the overrunning clutch mechanism 106 on the extended portion 102a of the rotary shaft 102. The conventional starter 1 has another disadvantage that the layout of the engine in the vehicle is much restrained because the electromagnetic switch 118 for operating the shift lever 117 and applying electricity to the DC motor 202 is placed alongside the DC motor to result in making the starter of the two-axial type. The conventional starter 1 has still another disadvantage that the assembling property thereof is not good because the weight of the starter is heavy and the number of component parts thereof is large. Since the electromagnetic switch 118 and the DC motor are disposed in parallel with each other in the conventional engine starter, it is necessary to take a space in the engine or in a vehicle or the like to house the electromagnetic switch in the space in attaching the engine starter to the engine. For that reason, there is a problem that the layout of the engine in the vehicle or the like is restricted. If the electromagnetic switch 118 and the DC motor are simply disposed in series with each other in order to solve the problem, the total length of the engine starter is increased to make it difficult to lay out the engine at the rear portion of the engine starter. This is another problem. If the overrunning clutch, which is separately constructed, the driving coil of the electromagnetic switch and so forth are placed in the armature in order to solve the former problem, it is difficult to secure a good assembling property and a sufficient processing accuracy and properly form the magnetic circuit to attain satisfactory performance and quality. This is still another problem. DE-A-2 44 80 69 describes an inline DC-motor and electromagnetic switch, in which a hollow drive shaft is located within the DC-motor and the pinion is moved forward to engage with the motor for starting the engine by means of a rod moved by an electromagnetic switch arrangement. A face contact type commutator is also shown. The actual contact to the commutator is provided by moving the brush against the face of the commutator, this movement being provided by the electromagnetic switch and the brush normally not being in contact with the commutator except when the engine is to be started. In front of the motor, remote from the electromagnetic switch, rollers are provided which allow a relative movement between a hollow drive shaft and a threaded tube. When the electromagnetic switch is operated, the rod moves forward and exerts force on a transmission shaft. This transmission shaft is able to move axially with respect to the motor, however, a screw thread is provided between the transmission shaft and the threaded tube so that the gear shaft can rotate as axial movement occurs. The axial movement brings a pinion into contact with the gear of the motor. SUMMARY OF THE INVENTION It is an object of the present invention to provide an engine starter which eliminates the above-described disadvantages. It is another object of the present invention to provide an engine starter, the size and weight of which are reduced and the number of component parts of which is decreased. It is a further object of the present invention to provide an engine starter in which an electromagnetic switch and an electric motor are disposed in series with each other to make the total length of the engine starter small enough to improve the assembling property thereof to an engine and which has good performance. The above objects are solved by an engine starter according to the present invention comprising electric motor means having a hollow rotary shaft and an armature core for providing a turning force to start an engine; one-way clutch means including a wedge-like cam formed on the inside surface of said hollow rotary shaft; hollow inner clutch means rotatably supported in said hollow rotary shaft through said one-way clutch means; rollers and roller springs each provided between said wedge-like cam and said hollow inner clutch means; pinion shaft means provided with a pinion which is engaged with a ring gear of said engine, and spline-fitted in said hollow inner clutch means to move in the axial direction thereof; electromagnetic switch means attached to one end of said electric motor means for turning on or off said electric motor means; moving body means which moves in conjunction with said electromagnetic switch to move said pinion shaft in the axial direction thereof to engage said pinion with said ring gear; stopper means provided on the peripheral portion of said pinion shaft means; and spring means provided between said stopper means and said hollow inner clutch means for returning said pinion shaft means, said stopper means coming into contact with the end of said hollow inner clutch means when said pinion shaft means is moved, said hollow rotary shaft having a large diameter portion and a small diameter portion characterized in that said armature core is provided on said large diameter portion of said hollow rotary shaft; said wedge-like cam is located within said armature core and said moving body means is partly located in said small diameter portion of said hollow rotary shaft. The pinion shaft is provided in the one-way clutch mechanism.The pinion shaft is moved by the moving body which is moved in conjunction with the action of the electromagnetic switch. The electric motor and the electromagnetic switch are disposed in series with each other to make the total length of the engine starter small enough to render the engine starter compact and symmetric with regard to the axis thereof. As a result, the assembling property of the engine starter to the engine and the quality of the engine starter are improved. Since the electromagnetic switch is located at the end of the DC motor coaxially therewith and the rotary output shaft is slidably supported in the hollow rotary shaft of the armature, the total length of the engine starter is decreased to greatly reduce the length of the yoke. Since such moment as to cause high stress in the front brace does not act between the bearing portion of the front brace and its surface attached to an engine, the thickness of the front brace can be decreased to make it possible to secure the front brace to the end of the yoke when molding the front brace from plastic to embed the end of the yoke positioned in a molding die. The front brace and the yoke can thus be integrally coupled to each other to substantially reduce the number of component parts of the engine starter and greatly diminish the total weight of the engine starter. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing a conventional engine starter; Fig. 2 is a sectional view showing an engine starter according to an embodiment of the present invention; Fig. 3 is a sectional view showing the side portion of the front brace of an engine starter according to another embodiment of the present invention; Fig. 4 is a sectional view showing the side portion of the front brace of an engine starter according to still another embodiment of the present invention; and Fig. 5 is a sectional view showing an engine starter according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be hereafter described in detail with reference to the drawings attached hereto. FIG. 2 shows an engine starter 10 which is one of the embodiments and of the coaxial type in which an electromagnetic switch is located at one end of a DC motor to dispose the hollow rotary shaft of the armature of the DC motor and the plunger rod of the electromagnetic switch coaxially with each other to stretch the plunger rod to a rotary output shaft through the internal opening of the hollow rotary shaft of the armature and shape the engine starter as a slender cylinder. The engine starter 10 has the DC motor 15 chiefly composed of permanent magnets 12 secured at circumferential intervals to the inside circumferential surface of a yoke 11 provided to form a magnetic circuit and constitute a casing, the armature 13 rotatably supported in the center of the yoke, and a face-contact-type commutator 14 provided at one end of the armature. The armature 13 comprises the hollow rotary shaft 16 and a core 17 mounted on the peripheral portion of the hollow rotary shaft. The inside circumferential surface of the hollow rotary shaft 16 has a recess having a plurality of cam surfaces 16a at circumferential intervals. The face-contact-type commutator 14, which is fitted on one end portion (which is the left-hand end portion as to FIG. 1) of the hollow rotary shaft 16, has a number of segments having surfaces extending perpendicularly to the axis of the hollow rotary shaft so as to slide in contact with a plurality of brushes 18 to perform commutation. The ends of an armature coil 19 wound on the armature core 17 are connected to the segments of the commutator 14. The brushes 18 are supported by brush holders 21 made of plastic and disposed inside a rear brace 20 formed separately from the yoke 11 and fitted thereon. The brushes 18 are located in pressure contact with the sliding surfaces of the commutator 14 by springs 22, out of openings provided in the rear brace 20. A bearing 23 is fitted on the inside circumferential surface of the central portion of the rear brace 20 to support the hollow rotary shaft 16 at the rear end thereof near the commutator 14. A fixed contact 24, which is connected to a terminal not shown in the drawing, is inserted and molded in the brush holder 21. A terminal 26 to which a lead wire 25 for the brush 18 on the positive side is welded is secured to the fixed contact 24 by a screw 27. An overrunning clutch mechanism is made of the cam surfaces 16a of the recess of the inside circumferential surface of the hollow rotary shaft 16. A tubular inner clutch member 28 is inserted in the internal opening of the hollow rotary shaft 16 so that the inner clutch member extends along the total axial length of each cam surface 16a of the hollow rotary shaft and is rotatably supported by bearings 30 and 31 to the hollow rotary shaft and a front brace 29 made of plastic and attached to the front end (which is the right-hand end as to FIG. 2) of the yoke 11. A plurality of wedge-shaped openings are defined by the outside circumferential surface of the inner clutch member 28 and the cam surfaces 16a of the recess of the hollow rotary shaft 16 of the armature 13. Rollers 32 for coupling the cam surfaces 16a and the outside circumferential surface of the inner clutch member 28 to each other through engagement and springs (which are not shown in the drawing) for pushing the rollers in such a direction as to engage them with the cam surfaces and the outside circumferential surface of the inner clutch member are provided in the wedge-shaped openings. The overrunning clutch mechanism comprises the cam surfaces 16a, the inner clutch member 28, the rollers 32, the springs and so forth. The hollow rotary shaft 16 of the armature 13 is used as the outer clutch member of the overrunning clutch mechanism. A pinion shaft 33, which is a rotary output shaft, is provided in the internal opening of the tubular inner clutch member 28. The inner clutch member 28 and the pinion shaft 33 are engaged with each other at helical splines 33a provided on the inside and outside circumferential surfaces of the inner clutch member and the pinion shaft. The front end of the pinion shaft 33 is integrally formed with a pinion 33b, which is engaged with the ring gear (which is not shown in the drawing)of an engine. The pinion shaft 33 is supported by a bearing 34 secured to the inside surface of the inner clutch member 28 near the rear end thereof. A spring 36 for moving the pinion shaft 33 back to the original position thereof is provided between the bearing 34 and a snap ring 35 mounted on the rear end portion of the pinion shaft. The rear end face of the pinion shaft 33 has a recess 37. A first holder 38, which has a cylindrical form and is open at one end, is movably fitted in the recess 37. A steel ball 39 is provided between the other closed end of the first holder 38 and the back surface of the recess 37 to receive a pushing force. The engine starter 10 also has an electromagnetic switch 40 which functions to slide the rotary output shaft 33, and also functions to connect the fixed contact 24 and a movable contact 50c to each other in response to the closure of the ignition switch (which is not shown in the drawing) of a vehicle to apply electricity from a battery to the DC motor 15. The electromagnetic switch 40 is coupled to the outside of the rear brace 20 by bolts 41, and comprises a driving coil 44 wound on a plastic bobbin supported by a front and a rear cores 43a and 43b for constituting a magnetism passage together with a case 42, a plunger 45 slidably supported in the central opening of the bobbin, and a moving assembly 46 attached to the plunger 45. The plunger 45 is urged by a helical spring 47 provided between the plunger and the front core 43a so that the plunger is returned to its original position shown in FIG. 2, when the ignition switch is open. The moving assembly 46 has a rod 48 secured at one end thereof to the plunger 45 and opposed at the other end thereof to the first holder 38 located at the rear end of the pinion shaft 33. A third holder 49 having an opening toward the pinion shaft 33 is secured to the peripheral surface of the rod 48 near the plunger 45. A movable contact bearer 50 having the movable contact 50c pinched between two electric insulators 50a and 50b is slidably fitted on the outside circumferential surface of the third holder 49. A second holder 51 is fitted on the outside circumferential surface of the front end portion of the rod 48 so that the second holder is slidable in the axial direction of the rod. A spring 52 is provided between the second holder 51 and the inner end of the opening of the third holder 49 to push the pinion shaft 33 forward (rightward as to FIG. 2). A spring 53 is provided between the front end face of the rod 48 and the inner end of the opening of the first holder 38 to push the pinion shaft 33 forward. A nonmagnetic plate 54 closes the rear end of the case 42 and serves as the rear wall of the electromagnetic switch 40 so that the plate stops the plunger 45 when it is moved back. Since no high moment acts to the front brace 29 of the engine starter 10, the front brace can be made of plastic at a small thickness. Since the engine starter 10 is of the coaxial type, the total length thereof is small and the axial length of the yoke 11 is therefore small. For that reason, the front brace 29 can be molded from the plastic so that one end of the yoke 11 positioned in a molding die is embedded in the plastic. At the time of the molding, a holder 29a for the bearing 31 for supporting the inner clutch member 28 is formed integrally with the front brace 29. The operation of the engine starter 10 is described from now on. When the ignition switch is open, the driving coil 44 is supplied with no electricity and therefore not excited, so that only the force of the spring 47 acts to the plunger 45. For that reason, the moving assembly 46 is in a posterior position, and the plunger 45 is in contact with the plate 54. Since the fixed contact 24 and the movable contact 50c are away from each other at that time, the DC motor 15 is at a standstill. Besides, the pinion shaft 33 is located back by the force of the spring 36. When the ignition switch is closed, the driving coil 44 is supplied with electricity to move the moving assembly 46 forward to bring the movable contact 50c into touch with the fixed contact 24. As a result, electricity is applied to the armature coil 19 through the brushes 18 and the commutator 14 so that the DC motor 15 is started. In the meantime, the pinion shaft 33 is pushed forward by the springs 52 and 53 of the moving assembly 46 so that the pinion 33b and the ring gear secured to the peripheral portion of the flywheel of the engine are engaged with each other simultaneously with the starting of the DC motor 15. When the pinion shaft 33 and the inner clutch member 28 are rotated in the reverse direction by the ring gear faster than the hollow rotary shaft 16 of the armature 13 after the starting of the engine, the inner clutch member and the hollow rotary shaft are disengaged from each other so that the hollow rotary shaft races. When the ignition switch is opened at the end of the starting of the engine, the supply of the electricity is ceased so that the moving assembly 46 is moved back together with the plunger 45 by the force of the spring 47 in the electromagnetic switch 40 and the pinion shaft 33 is moved back by the force of the spring 36. FIG. 3 shows an engine starter which is another one of the embodiments and in which the hollow rotary shaft 16 of an armature is supported at the front end of the shaft by a bearing 31 fitted in a holder 29a formed around the central opening of a front brace 29. FIG. 4 shows an engine starter which is still another one of the embodiments and in which a pinion shaft 33 is supported by a bearing 31 fitted in a holder 29a formed around the central opening of a front brace 29. The thickness of each of the front braces 29 of the engine starters shown in FIGS. 3 and 4 can be also made small. Besides, the total length of a yoke 11 is small. As a result, the front brace 29 can be secured to the end of the yoke 11 when the front brace is molded. Another embodiment of the present invention is hereafter described in detail with reference to the drawing attached hereto. FIG. 5 shows an engine starter which is the embodiment and has a DC motor including an armature 301, the core 302 of the armature, the rotary shaft 303 of the armature, on which the core 302 is press-fitted and which is provided with a wedge-like cam 303a in the rotary shaft to constitute an overrunning clutch function, a face-contact-type commutator 304 mounted on the rear portion of the rotary shaft 303 and having a face which slides in contact with brushes 305 to perform commutation and is perpendicular to the axis of the rotary shaft, and an armature coil 306 wound on the core 302 and connected to the commutation and is perpendicular to the axis of the rotary shaft. The brushes 305 are pushed forward by springs 305a provided behind the brushes, so that the fronts of the brushes are located in pressure contact with the sliding face of the commutator 304. A plurality of permanent magnets 307 are secured to the inside circumferential surface of a yoke 308 serving as a magnetism passage, so that the permanent magnets function as a field for the armature 301. The yoke 308 is fitted at the rear thereof to a rear brace 309 and at the front thereof to a front brace 310. A bearing 311 is mounted on the rear end portion of the rotary shaft 303 and fitted in the rear brace 309. A number of holes, which is equal to that of the brushes 305, are provided in the rear brace 309 around a hole fitted with the bearing 311 and are located in positions corresponding to those of the brushes, so that the brushes are located in contact with the commutator 304. Brush holders 312 made of plastic house the brushes 305 and the springs 305a. A fixed contact 313, which is connected to a terminal not shown in the drawing, is inserted and molded in the rear portion of the brush holder 312 for the brush 305 on the positive side. A terminal 314, to which a lead wire 305b for the brush 305 on the positive side is welded, is secured to the fixed contact 313 by a screw 315. Rollers 316 are provided on the cam 303a formed on the inside surface of the rotary shaft 303, so that the rollers and roller springs perform an overrunning function. A bearing 318 is fitted on the outside circumferential surface of the middle portion of the inner clutch member of an overrunning mechanism to support the rotary shaft 303 at the front end thereof. A bearing 319 is fitted in the front brace 310 to support the inner clutch member 317 at the front end thereof. A helical spline 317a is formed on the inside surface of the inner clutch member 317. A helical spline 320c is provided on the outside circumferential surface of the middle portion of a pinion shaft 320, whose tip portion has a pinion 320a and a flange 320b for preventing dust and water from entering. The helical splines 317a and 320c are fitted with each other so that the spline 320c is slidable back and forth. A stopper 321 is attached to the rear portion of the pinion shaft 320. A bearing 322 is fitted in the inner clutch member 317 to support the pinion shaft 320 at the rear portion thereof and bear the front end of a return spring 323 for the pinion shaft. The pinion shaft 320 is moved forward in the axial direction thereof while deforming the spring 323 in cooperation with the stopper 321. When the stopper 321 has come into contact with the rear end face 317b of the inner clutch member 317, the forward movement of the pinion shaft 320 is terminated. The engine starter also has an electromagnetic switch 324 coupled to the rear brace 309 by bolts 325. The electromagnetic switch 324 functions to move the pinion shaft 320 forward, and also functions to connect a movable contact 328 to the fixed contact 313 in response to the closure of an ignition switch so as to apply electricity from a battery to the DC motor. The movable contact 328 is provided on electric insulators 327a and 327b on the peripheral portion of a moving assembly 326, which acts to push the pinion shaft 320 from behind. The moving assembly 326 includes a plunger 326a, a rod 326b, a second holder 326c, and a first holder 326d secured between the plunger and the rod and fitted with the moving contact 328 and so forth. The rear end of the rod 326b is calked to the rear end face of the plunger 326a. A spring 329 is provided around the rod 326b between the first and the second holders 326d and 326c to push the pinion shaft 320. A third holder 330 is urged by a push spring 331 to push the pinion shaft 320. A steel ball 332 is provided between the front end face of the third holder 330 and the rear recess of the pinion shaft 320 to transmit a pushing force. A driving coil 333 is wound on a plastic bobbin 333a to move the plunger 326a. A rear core 334a, a front core 334b and a case 335 form a magnetic circuit. A nonmagnetic plate 336 is provided as the rear wall of the electromagnetic switch 324 to stop the plunger 326a when it is moved back. A seal 337 is provided between the case 335 and the plate 336 to prevent water from entering. A spring 338 is provided between the plunger 326a and the front core 334b to return the moving assembly 326 to the original position thereof when the ignition switches opened. Bolts 339 couple the front and the rear braces 310 and 309 to each other. The operation of the engine starter is described in details from now on. When the ignition switch not shown in the drawing is open, the driving coil 333 is supplied with no electricity so that only the force of the spring 338 acts to the plunger 326a. For that reason, the moving assembly 326 is in a posterior position, and the plunger 326a is in contact with the plate 336. At that time, the fixed contact 313 and the movable contact 328 are away from each other so that the DC motor is at a standstill. The pinion shaft 320 is in a posterior position because of the action of the spring 323 so that the rear of the flange 320b is at a standstill in contact with the front end face of the inner clutch member 317. When the ignition switch is closed, the driving coil 333 is supplied with electricity to move the plunger 326a to move the moving assembly 326 forward to bring the movable contact 328 into touch with the fixed contact 313. As a result, the other electricity is applied to the armature coil 306 through the brushes 305 and the commutator 304 so that the DC motor is started. In the meantime, the pinion shaft 320 is pushed forward by the pressure springs 329 and 331 of the moving body 326 so that the pinion 320a and a ring gear secured to the peripheral portion of the flywheel of an engine begin to be engaged with each other at the same time as the starting of the DC motor. Immediately after the starting of the engine, the pinion shaft 320 and the inner clutch member 317 are moved together with the ring gear because of the one-way overrunning function so that the pinion shaft and the inner clutch member race relative to the armature 301. When the ignition switch is opened at the end of the starting of the engine, the supply of the electricity is ceased so that the moving assembly 326 is moved back by the spring 338 in the electromagnetic switch 324 and the pinion 320 is moved back by the spring 323. Although the face-contact-type-commutator 304 is provided in the above-described embodiment, a different type of commutator may be provided instead. Although the permanent magnets 307 are provided to function as the field of the DC motor in the above-described embodiment, cores and coils wound thereon may be provided instead of the permanent magnets. Although the pinion shaft 320 and the pinion 320a are integrated with each other in the above-described embodiment, the pinion may be spline-fitted on the pinion shaft and provided with a stopper, instead.

Claims: An engine starter, comprising: electric motor means having a hollow rotary shaft (16;303) and an armature core (13,302) for providing a turning force to start an engine; one-way clutch means including a wedge-like cam (16a;303a) formed on the inside surface of said hollow rotary shaft (16;303); hollow inner clutch means (28;317) rotatably supported in said hollow rotary shaft (16;303) through said one-way clutch means; rollers (32;316) and roller springs each provided between said wedge-like cam (16a;303a) and said hollow inner clutch means (28;317); pinion shaft means (33;320) provided with a pinion (33b;320a) which is engaged with a ring gear of said engine, and spline-fitted in said hollow inner clutch means (28;317) to move in the axial direction thereof; electromagnetic switch means (40;324) attached to one end of said electric motor means for turning on or off said electric motor means; moving body means (48) which moves in conjunction with said electromagnetic switch (40;324) to move said pinion shaft means (33;320) in the axial direction thereof to engage said pinion (33b;320a) with said ring gear; stopper means (35;321) provided on the peripheral portion of said pinion shaft means (33;320) and; spring means (36;323) provided between said stopper means (35;321) and said hollow inner clutch means (28;317) for returning said pinion shaft means (33;320), said stopper means (35;321) coming into contact with the end of said hollow inner clutch means (28;317) when said pinion shaft means (33;320) is moved; said hollow rotary shaft (16;303) having a large diameter portion and a small diameter portion, characterized in that said armature core (13;302) is provided on said large diameter portion of said hollow rotary shaft (16;303), said wedge-like cam (16a;303a) is located within said armature core (13,302); and said moving body means is partly located in said small diameter portion of said hollow rotary shaft (16;303). An engine starter as claimed in claim 1, further comprising bearing means (30,31;318,319) provided between a front brace (29) of said electric motor means and said hollow inner clutch means (28;317). An engine starter as claimed in any one of claims 1 or 2, in which the armature (13;301) of said electric motor is provided with a face-contact-type-commutator (14;304) having a face in sliding contact with brushes (18;305) which is perpendicular to the axis of said hollow rotary shaft (16;303). An engine starter as claimed in any one of claims 1 to 3, in which a flange (320b) is provided on said pinion (320a) which projects from said hollow inner clutch means (317) of said pinion shaft means (320).

Inventors: ISOZUMI, SHUZOO MITSUBISHI DENKI K.K., TANAKA, TOSHINORI MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1988
Main classification: F02N15
IPC codes: F02N15