JP2010074896A - Electric motor and engine startup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of part items of a magnet fixing part in an electric motor, to improve the water discharging performance of the magnet fixing part, and to obtain structure which makes water hardly stay in a yoke and a magnet cover. <P>SOLUTION: This engine startup device 1 is driven by the magnet field electric motor 2. Magnets 26 of the electric motor 2 are fixed in a motor housing 21 by the magnet cover 88. The magnet cover 88 includes a flange 89 press-fixed to the internal peripheral face 21a of the motor housing 21 and a cylindrical holder 91, and sandwiches the magnets 26 between the holder 91 and the yoke internal peripheral face 21a. The flange 89 has a water discharging hole 93, the water discharging hole 93 is arranged so as to face an interval 92 in the circumferential direction which is formed between the adjacent magnets 26, and water intruded into the magnet cover 88 is discharged from the water discharging hole 93. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnet fixing structure for an electric motor, and more particularly to a magnet fixing structure for an electric motor used as a drive source for an engine starting device.

  Conventionally, in a DC electric motor, a permanent magnet (magnet) is generally used as a field pole. For example, an electric motor of a magnet field is also used in an engine starter (starter) for starting an engine of an automobile, a motorcycle, a large generator, etc., and Patent Document 1 discloses a pinion gear by the rotational force of this motor. An engine starting device of a type in which is moved in the axial direction and meshed with an engine ring gear is described.

  FIG. 5 is an explanatory diagram showing a configuration of a magnet fixing portion in such a magnet field electric motor. As shown in FIG. 5, in the motor, a plurality of magnets 102 and auxiliary poles 103 are arranged on the inner peripheral surface of the yoke 101. A magnet holder 105 made of a leaf spring having a U-shaped cross section is mounted in the gap 104 between the adjacent pair of magnets 102 and the auxiliary pole 103. In addition, a cylindrical magnet cover 107 having a flange 106 formed at one end is press-fitted and fitted inside the magnet 102 and the auxiliary electrode 103. The magnet cover 107 is formed with a protruding portion 108 that is protruded and deformed radially outward at a portion facing the gap 104.

In the motor of FIG. 5, the magnet 102 and the auxiliary pole 103 are pressed in the radial direction by the magnet cover 107 and are in close contact with the inner peripheral surface of the yoke 101. Further, the magnet 102 and the auxiliary pole 103 are prevented from rotating in the circumferential direction by the protrusion 108 of the magnet holder 105 and the magnet cover 107 while ensuring a gap between the adjacent magnet / auxiliary pole pair. Thereby, the magnet 102 and the auxiliary pole 103 are attached to the inner peripheral surface of the yoke 101 in a state where movement in the radial direction and the circumferential direction is restricted.
JP-A-64-5343 Japanese Utility Model Publication No. 63-143037

  However, in such a magnet fixing structure, there is a problem in that fixing parts such as the magnet holder 105 are required by the number of magnet / auxiliary pole pairs, which causes a cost increase. Further, as the number of parts increases, the number of assembling steps also increases. In this respect as well, the cost is increased, so that improvement has been demanded. Further, in the case of the structure shown in FIG. 5, the gap 104 in which the magnet holder 105 is mounted is a space surrounded by the yoke 101, the magnet cover 107, the magnet 102, and the auxiliary electrode 103. There was also a problem that it was difficult to be discharged and water could accumulate therein.

  The object of the present invention is to reduce the product cost by reducing the number of parts of the magnet fixing portion in the electric motor of the magnet field, and improve the drainage of the magnet fixing portion, so that water is not easily collected in the yoke and the magnet cover. It is to make it a structure.

  An electric motor of the present invention includes a cylindrical metal yoke, a plurality of magnets attached to the inner peripheral surface of the yoke, a metal auxiliary pole disposed adjacent to the magnet, and an inner side of the yoke And a flange that is press-fitted and fixed to the inner peripheral surface of the yoke, and a cylindrical holder portion that is formed integrally with the flange, and the magnet is disposed between the holder portion and the inner peripheral surface of the yoke. And a drain hole formed on the flange of the magnet cover and disposed so as to face a gap formed in a portion where the magnet and the auxiliary electrode do not exist. .

  In the present invention, there is provided a magnet cover that includes a flange press-fitted and fixed to the inner peripheral surface of the yoke and a cylindrical holder portion, and sandwiches the magnet and the auxiliary electrode between the holder portion and the yoke inner peripheral surface. By using it, it is possible to mount and fix the magnet and the auxiliary pole in the yoke with only the magnet cover without attaching a fixing part between the individual magnets. For this reason, the number of parts can be reduced and the number of assembling steps can be reduced. Also, by forming a drain hole in the flange of the magnet cover and placing it facing the gap formed in the part where the magnet and auxiliary pole do not exist, even if water enters the magnet cover, Water is discharged from the drain hole, and it is difficult for water to collect between the yoke and the magnet cover.

  In the electric motor, the yoke may be provided with a drain hole communicating with the drain hole, and a drain cover having a labyrinth structure may be attached to the outside of the drain hole. good.

  On the other hand, the engine starter of the present invention is an engine starter that uses an electric motor as a drive source and meshes a pinion rotated by the electric motor with an engine ring gear to start the engine. A cylindrical metal yoke, a plurality of magnets attached to the inner peripheral surface of the yoke, a metal auxiliary pole disposed adjacent to the magnet, and an inner peripheral surface side of the yoke. A flange press-fitted and fixed to the inner peripheral surface of the yoke, and a cylindrical holder portion formed integrally with the flange, and the magnet is sandwiched between the holder portion and the inner peripheral surface of the yoke A magnet cover and a gap formed on the flange of the magnet cover and facing a gap formed in a portion where the magnet and the auxiliary pole do not exist. And having a drain hole that is, a.

  In the present invention, an electric motor used as a drive source of an engine starter includes a flange press-fitted and fixed to the inner peripheral surface of the yoke and a cylindrical holder portion, and the holder portion and the inner peripheral surface of the yoke By using a magnet cover that sandwiches the magnet and auxiliary pole between the magnet and the magnet, the auxiliary pole can be mounted and fixed in the yoke only with the magnet cover without attaching a fixing part between the individual magnets. it can. For this reason, the number of parts of the engine starter can be reduced and the number of assembling steps can be reduced. Also, by forming a drain hole in the flange of the magnet cover and placing it facing the gap formed in the part where the magnet and auxiliary pole do not exist, even if water enters the magnet cover, Water is discharged from the drain hole, and it is difficult for water to collect between the yoke and the magnet cover.

  According to the electric motor of the present invention, a cylindrical metal yoke, a flange that is press-fitted and fixed to the inner peripheral surface of the yoke with an electric motor having a plurality of magnets and auxiliary poles attached to the inner peripheral surface of the yoke, Since a magnet cover that includes a cylindrical holder portion and sandwiches a magnet and an auxiliary pole between the holder portion and the inner peripheral surface of the yoke is used, there is no need to attach a fixing part between individual magnets. The magnet and auxiliary pole can be mounted and fixed in the yoke only by the magnet cover. For this reason, the number of parts can be reduced, the number of assembling steps can be reduced, and the product cost can be reduced. In addition, a drain hole is formed in the flange of the magnet cover, and it is arranged facing the gap formed in the part where the magnet and auxiliary pole do not exist, so even if water gets into the magnet cover, the holder The water inside can be discharged from this drain hole, and it becomes difficult for water to collect between the yoke and the magnet cover.

  According to the engine starter of the present invention, an electric motor that is used as a drive source of the engine starter and has a cylindrical metal yoke, a plurality of magnets and auxiliary poles attached to the inner peripheral surface of the yoke, Because it has a flange that is press-fitted and fixed to the inner peripheral surface of the yoke and a cylindrical holder portion, and a magnet cover that sandwiches the magnet and the auxiliary pole between the holder portion and the inner peripheral surface of the yoke is used. Without attaching a fixing part between individual magnets, the magnet and the auxiliary electrode can be mounted and fixed in the yoke only by the magnet cover. For this reason, the number of parts can be reduced, the number of assembling steps can be reduced, and the product cost can be reduced. In addition, a drain hole is formed in the flange of the magnet cover, and it is arranged facing the gap formed in the part where the magnet and auxiliary pole do not exist, so even if water gets into the magnet cover, the holder The water inside can be discharged from this drain hole, and it becomes difficult for water to collect between the yoke and the magnet cover.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of an engine starter using an electric motor as a drive source according to an embodiment of the present invention, in which the upper side from the center line shows a stationary state and the lower side shows an energized state. . An engine starter (starter) 1 shown in FIG. 1 is used for starting an automobile engine, and uses a magnet field electric motor (hereinafter abbreviated as a motor) 2 as a drive source.

  The motor 2 is connected to a reduction gear 3, and the rotation of the motor 2 is transmitted to the drive shaft 4 via the reduction gear 3. An overrunning clutch 5 and a pinion gear 6 are provided on the drive shaft (output shaft) 4 so as to be movable in the axial direction. The engine starter 1 is a single-axis type starter in which a magnet switch 7 is arranged coaxially with the drive shaft 4, and the pinion gear 6 is axially moved together with the overrunning clutch 5 by the action of the magnet switch 7. It moves and meshes with the ring gear 8 of the engine.

  The motor 2 has a configuration in which an armature 22 is rotatably disposed in a cylindrical motor housing 21. The motor housing 21 also serves as the yoke of the motor 2 and is made of a magnetic metal such as iron. A metal end cover 23 is attached to the right end portion of the motor housing 21. On the other hand, the left end portion of the motor housing 21 is attached to a gear cover 24 in which the pinion gear 6 is accommodated. The end cover 23 is fixed to the gear cover 24 by a set bolt 25, and the motor housing 21 is fixed between the end cover 23 and the gear cover 24.

  A plurality (six in this case) of magnets 26 and auxiliary poles 87 are fixed to the inner peripheral surface of the motor housing 21 in the circumferential direction. As shown in FIG. 1, a stainless steel magnet cover 88 is attached inside the magnet 26 and the auxiliary pole 87. 2A and 2B are diagrams showing the configuration of the magnet cover 88, wherein FIG. 2A is a side view of the magnet cover 88, and FIG. 2B is a left side view thereof. 3A and 3B are diagrams showing the configuration of the motor housing 21 in a state where the magnet 26 and the auxiliary pole 87 are fixed by the magnet cover 88, wherein FIG. 3A is a sectional view thereof and FIG. 3B is a right side view thereof. In FIG. 1, the thickness of the magnet cover 88 is exaggerated for easy understanding.

  As shown in FIG. 2, the magnet cover 88 has a cylindrical shape in which a flange 89 is formed at one end. The flange 89 is formed integrally with the cylindrical holder portion 91, and its outer diameter is slightly smaller than the inner diameter of the motor housing 21. The magnet cover 88 is inserted into the motor housing 21 from one end side (left side in FIG. 3A) of the motor housing 21, and at that time, the flange 89 is press-fitted into the motor housing 21. Thereby, the magnet cover 88 is press-fitted and fixed in the motor housing 21, and the magnet 26 and the auxiliary pole 87 are sandwiched between the outer peripheral surface 91 a of the holder portion 91 and the inner peripheral surface 21 a of the motor housing 21.

  After the magnet cover 88 is press-fitted and fixed in the motor housing 21, the tip of the holder portion 91 is deformed to increase in diameter toward the outer side in the circumferential direction, and a crimped portion 91 b is formed. Further, in the magnet cover 88, a protruding portion 91 c that protrudes and deforms outward in the radial direction is formed at a portion facing a circumferential gap 92 formed between the magnet 26 and the auxiliary pole 87 of the adjacent pole. . Thereby, the magnet 26 is attached to the outer peripheral surface 91a of the holder portion 91 in a state in which the magnet 26 is prevented from coming off in the radial direction, the axial direction, and the circumferential direction. Therefore, in the motor 2, the magnet 26 and the auxiliary pole 87 can be mounted and fixed in the motor housing 21 only by the magnet cover 88 without attaching fixing parts for each gap. For this reason, the number of parts can be reduced, the number of assembling steps can be reduced, and the product cost can be reduced.

  On the other hand, a plurality of drain holes 93 are formed in the flange 89 at equal intervals along the circumferential direction. The drain holes 93 are formed in correspondence with the gap 92 between the magnet 26 and the auxiliary pole 87, and six are formed at 60 ° intervals in the motor 2. As shown in FIG. 3B, the drain hole 93 is located at a position facing the gap 92 when the magnet cover 88 is assembled in the motor housing 21, that is, at a portion where the magnet 26 and the auxiliary pole 87 do not exist. Arranged. Thus, even if water enters the magnet cover 88, the water in the holder is discharged from the drain hole 93. Therefore, it is difficult for water to collect between the motor housing 21 and the magnet cover 88, improving the reliability of the motor 2 and improving the reliability of the engine starter 1.

  Further, the motor housing 21 is provided with a drain hole 94 for discharging the water discharged from the drain hole 93 to the outside of the motor. The drainage hole 94 communicates with the drainage hole 93 in the motor housing 21, and is formed at the nearest position where one of the drainage holes (93a) and the circumferential position overlap. That is, it arrange | positions so that the circumferential direction position of the center axis | shaft O of both the holes 93a and 94 extended along a radial direction may become substantially the same position (about less than +/- 1 degree). By this drainage hole 94, the water that enters the magnet cover 88 and is discharged from the drainage hole 93 is smoothly discharged outside the motor through the drainage hole 94. Further, since the drain hole 94 is arranged so as to face directly below (toward the ground) when the engine starter 1 is attached to the vehicle body, the water discharged from the drain hole 94 drops below the motor (on the ground). , It will not stay around the motor.

  A drain cover 95 made of synthetic resin is attached to the drain hole 94. 4A and 4B are views showing the configuration of the drain cover 95, where FIG. 4A is a bottom view and FIG. 4B is a right side view. As shown in FIG. 4, the drain cover 95 has a labyrinth structure, and a labyrinth portion 96 in which partition walls 96a and 96b are alternately arranged is formed therein. The drain cover 95 is attached to the drain hole 94 by a snap fit portion 97 and includes a communication port 98 corresponding to the drain hole 94 and a drain port 99. The water discharged from the drain hole 94 reaches the drain port 99 through the labyrinth portion 96 from the communication port 98 and is discharged from there to the outside of the motor. As described above, by attaching the drain cover 95 having a labyrinth structure to the drain hole 94, it is possible to drain the water from the inside while preventing the water from entering from the outside.

  An armature 22 is disposed inside the magnet 26. The armature 22 includes an armature core 28 fixed to the motor shaft 27 and an armature coil 29 wound around the armature core 28. The right end portion of the motor shaft 27 is rotatably supported by a metal bearing 31 attached to the end cover 23. On the other hand, the left end portion of the motor shaft 27 is rotatably supported by the end portion of the drive shaft 4 to which the pinion gear 6 and the like are attached. A bearing portion 32 is recessed at the right end portion of the drive shaft 4, and the motor shaft 27 is rotatably supported by a metal bearing 33 attached thereto. As a result, the drive shaft 4 is arranged coaxially with the motor shaft 27 of the motor 2.

  A commutator 34 that is externally fitted and fixed to the motor shaft 27 is disposed adjacent to one end side of the armature core 28. A plurality of commutator pieces 35 formed of a conductive material are attached to the outer peripheral surface of the commutator 34, and the end of the armature coil 29 is fixed to each commutator piece 35. A brush holder 36 is attached to the left end portion of the motor housing 21. In the brush holder 36, a plurality of brush accommodating portions 37 are arranged at intervals in the circumferential direction. Each brush accommodating portion 37 is internally provided with a brush 38 that can be moved in and out. The protruding tip end (inner diameter side tip) of the brush 38 is in sliding contact with the outer peripheral surface of the commutator 34.

  A pigtail (not shown) is attached to the rear end side of the brush 38 and is electrically connected to the first plate 41 a of the conductive plate 41 provided in the brush holder 36. The conductive plate 41 includes the first plate 41a and a second plate 41b that is electrically connected to the power terminal 44. The insulating portion 41c that insulates the plates 41a and 41b from each other. (Hereinafter, the first and second plates 41a and 41b are abbreviated as the plate 41a and the plate 41b, respectively). A switch plate 43 is disposed opposite to the insulating portion 41 c, and a switch portion 42 is formed by both electrical contacts of the conductive plate 41 (plates 41 a and 41 b) and the switch plate 43.

  The switch plate 43 is attached to the switch shaft 45, and when the ignition switch of the engine is turned on and the magnet switch 7 is energized, the switch shaft 45 moves to the left. When the switch plate 43 comes into contact with the plates 41a and 41b, the insulating portion 41c is conducted and the switch portion 42 is turned on. As a result, the power terminal 44 to which the power supply cable (not shown) is attached is electrically connected to the brush 38, and power is supplied from the battery to the commutator 34. On the other hand, when the ignition switch is OFF, the insulating portion 41c is opened and the switch portion 42 is turned OFF, a gap is formed between the conductive plate 41 and the switch plate 43, and power supply to the motor 2 is stopped. To do.

  The planetary gear mechanism 11 of the reduction gear 3 is provided with an internal gear unit 46 and a drive plate unit 47. The internal gear unit 46 is fixed to the right end portion of the gear cover 24, and an internal ring gear 48 is formed on the inner peripheral side thereof. A metal bearing 49 is housed in the center of the internal gear unit 46, and the right end side of the drive shaft 4 is rotatably supported. The drive plate unit 47 is fixed to the right end of the drive shaft 4, and planetary gears 51 are attached at equal intervals. The planetary gear 51 is rotatably supported by a support pin 53 fixed to the base plate 52 via a metal bearing 54. The planetary gear 51 meshes with the internal ring gear 48.

  A sun gear 55 is formed at the left end of the motor shaft 27. The sun gear 55 meshes with the planetary gear 51, and the planetary gear 51 revolves between the sun gear 55 and the internal ring gear 48 while rotating. When the motor 2 operates, the sun gear 55 rotates together with the motor shaft 27, and the planetary gear 51 revolves around the sun gear 55 while meshing with the internal ring gear 48 as the sun gear 55 rotates. As a result, the base plate 52 fixed to the drive shaft 4 rotates, and the rotation of the motor shaft 27 is decelerated and transmitted to the drive shaft 4.

  The overrunning clutch 5 transmits the rotation decelerated by the planetary gear mechanism 11 to the pinion gear 6 in one rotation direction. The overrunning clutch 5 has a configuration in which a roller 58 and a clutch spring (not shown) are arranged between a clutch outer 56 and a clutch inner 57. The clutch outer 56 includes a boss portion 56 a and a clutch portion 56 b, and the boss portion 56 a is attached to the helical spline portion 61 of the drive shaft 4. A spline portion 62 that meshes with the helical spline portion 61 is formed on the inner peripheral side of the boss portion 56a. As a result, the clutch outer 56 can move in the axial direction along the helical spline portion 61 on the drive shaft 4.

  A stopper 63 is attached to the drive shaft 4. The stopper 63 is restricted from moving in the axial direction by a circlip 64 attached to the drive shaft 4. One end of a gear return spring 65 is attached to the stopper 63. The other end side of the gear return spring 65 is in contact with the inner end wall 66 of the boss portion 56a. The clutch outer 56 is urged to the right by the gear return spring 65, and the clutch outer 56 is held at a position in contact with a clutch stopper 67 fixed to the gear cover 24 during normal operation (when power is not supplied). Is done.

  A clutch inner 57 formed integrally with the pinion gear 6 is disposed on the inner periphery of the clutch portion 56 b of the clutch outer 56. A plurality of sets of rollers 58 and clutch springs are disposed between the clutch outer 56 and the clutch inner 57. A clutch cover 68 is externally provided on the outer periphery of the clutch portion 56 b, and a clutch washer 69 is attached between the left end surface of the clutch portion 56 b and the clutch cover 68. By this clutch washer 69, the roller 58 and the clutch spring are accommodated on the inner peripheral side of the clutch portion 56b in a state where movement in the axial direction is restricted.

  The inner peripheral wall of the clutch portion 56b is a cam surface, and a wedge-shaped slope portion and a curved surface portion are formed. The roller 58 is normally pushed to the curved surface side by a clutch spring. When the clutch outer 56 rotates and the roller 58 is sandwiched between the wedge-shaped inclined surface and the outer peripheral surface of the clutch inner 57 against the urging force of the clutch spring, the clutch inner 57 is connected to the clutch outer via the roller 58. Rotate integrally with 56. As a result, when the motor 2 operates and the drive shaft 4 rotates, the rotation is transmitted from the clutch outer 56 to the clutch inner 57 via the roller 58, and the pinion gear 6 rotates.

  On the other hand, when the engine is started and the clutch inner 57 rotates faster than the clutch outer 56, the roller 58 moves to the curved surface side, and the clutch inner 57 is idled with respect to the clutch outer 56. That is, when the clutch inner 57 is in an overrun state, the roller 58 is not sandwiched between the wedge-shaped slope and the outer peripheral surface of the clutch inner, and the rotation of the clutch inner 57 is not transmitted to the clutch outer 56. Therefore, even if the clutch inner 57 is rotated at a higher rotational speed from the engine side after the engine is started, the rotation is interrupted by the overrunning clutch 5 and is not transmitted to the motor 2 side.

  A pinion gear 6 is integrally formed on the left end side of the clutch inner 57. The pinion gear 6 (clutch inner 57) is a steel member formed by cold forging, and chrome steel (for example, SCr 420H) subjected to carburizing treatment is used. A shaft hole 71 is formed on the inner diameter side of the pinion gear 6, and a pinion gear metal 72 is attached to the shaft hole 71. The pinion gear 6 is rotatably supported by the drive shaft 4 via the pinion gear metal 72. On the other hand, a spring accommodating portion 73 is formed on the inner diameter side of the clutch inner 57, and a stopper 63 and a gear return spring 65 are accommodated therein.

  The magnet switch 7 is arranged coaxially with the drive shaft 4 on the left side of the planetary gear mechanism 11 and is concentric with the motor 2 and the planetary gear mechanism 11. The magnet switch 7 includes a steel fixed portion 74 fixed to the gear cover 24 and a movable portion 75 that is movable in the left-right direction along the bobbin 78, that is, is movable relative to the bobbin 78. The fixed portion 74 is provided with a case 76 fixed to the gear cover 24, a coil 77 accommodated in the case 76, and a bobbin 78 attached to the inner peripheral side of the case 76. The coil 77 is electrically connected to an ignition switch (not shown). The movable portion 75 is provided with a movable iron core 79 to which the switch shaft 45 is attached. A gear plunger 81 is attached to the inner peripheral side of the movable iron core 79. A switch return spring 86 is attached to the outer peripheral side (lower end side in the figure) of the movable iron core 79. The other end side of the switch return spring 86 is in contact with the gear cover 24, and the movable iron core 79 is urged to the right.

  A bracket plate 82 is further fixed to the inner periphery of the movable iron core 79. One end of a plunger spring 83 is fixed to the bracket plate 82 by caulking. The other end of the plunger spring 83 is in contact with the gear plunger 81 when the ignition key switch is OFF (in the upper half state of FIG. 1). The gear plunger 81 is attached to the left by the plunger spring 83. It is energized. The gear plunger 81 is attached to the drive shaft 4 so as to be movable in the axial direction, and a sliding iron core 84 is interposed between the inner peripheral surface of the movable iron core 79.

  The gear cover 24 is formed by aluminum die casting, and the left end side of the drive shaft 4 is rotatably supported by a left end portion of the gear cover 24 via a metal bearing 85. A clutch stopper 67 made of a synthetic resin (for example, glass fiber reinforced polyamide), a case 76 and the like are fixed in the gear cover 24. Further, a motor housing 21 and an end cover 23 are fixed to the right end surface side of the gear cover 24 by a set bolt 25.

  Next, the engine starting operation using such an engine starting device 1 will be described. First, when the ignition key switch of the automobile is OFF, the clutch outer 56 is in contact with the clutch stopper 67 by the biasing force of the gear return spring 65 as shown in the upper half of FIG. At this time, the switch plate 43 is separated from the conductive plate 41, and power supply to the motor 2 is not performed. Further, the pinion gear 6 is in the right disengagement position and is not engaged with the ring gear 8.

  On the other hand, when the ignition key switch is turned on, first, a current flows through the coil 77 and an attractive force is generated in the magnet switch 7. When the coil 77 is excited, a magnetic path passing through the case 76 and the bobbin 78 is formed, and the movable iron core 79 is attracted to the left. When the movable iron core 79 is sucked to the left, the bracket plate 82 moves to the left, and the plunger spring 83 is compressed. The repulsive force of the plunger spring 83 at this time is set to be larger than the repulsive force of the gear return spring 65, and the gear plunger 81 is moved to the left by the suction force applied to the sliding iron core 84 and the plunger spring 83. Pressed. As a result, the clutch outer 56 moves on the helical spline portion 61 along the axial direction, and the pinion gear 6 also moves leftward.

  On the other hand, when the movable iron core 79 moves to the left against the urging force of the switch return spring 86, the switch shaft 45 also moves to the left, the switch plate 43 contacts the conductive plate 41, and the contact is closed. As a result, the power supply terminal 44 and the brush 38 are electrically connected, power is supplied to the commutator 34, the motor 2 operates, and the armature 22 rotates. When the motor 2 operates and the armature 22 rotates, the drive shaft 4 rotates through the planetary gear mechanism 11.

  As the drive shaft 4 rotates, the clutch outer 56 attached to the helical spline portion 61 also rotates. The helical spline portion 61 has a twisting direction set in consideration of the rotational direction of the drive shaft 4. When the rotational speed of the clutch outer 56 increases, the inertial mass causes the clutch outer 56 to move along the helical spline portion 61. Move to the left. When the clutch outer 56 jumps to the left as the motor 2 rotates, the pinion gear 6 moves to the left together with the clutch outer 56, and the pinion gear 6 meshes with the ring gear 8. That is, with the ignition key switch ON, the pinion gear 6 is first pushed to the left by the gear plunger 81, and then pops out to the left at a stroke with the operation of the motor 2 to mesh with the ring gear 8.

  As a result, the pinion gear 6 moves to the operating position as shown in the lower half of FIG. 1, the rotation of the motor 2 is transmitted to the ring gear 8, and the ring gear 8 rotates. The ring gear 8 is connected to the crankshaft of the engine. As the ring gear 8 rotates, the crankshaft rotates and the engine is started. When the engine is started, the pinion gear 6 is rotated at a high speed by the ring gear 8, but the rotation is not transmitted to the motor 2 side due to the action of the overrunning clutch 5.

  When the clutch outer 56 moves leftward, the gear return spring 65 is also pushed by the clutch outer 56 and contracted. Further, the plunger spring 83 pushes the gear plunger 81 to the left, and is released when the pinion gear 6 and the ring gear 8 are completely engaged with each other, so that a natural length state is obtained. Therefore, a slight gap is generated between the gear plunger 81 and the plunger spring 83 in contact with the clutch outer 56 as in the lower half state of FIG.

  When the engine is started, the pinion gear 6 is rotated at a high speed, and the overrunning clutch 5 is rotated in the idling direction. When the overrunning clutch 5 is rotated in the idling direction, idling torque is generated in the clutch, and a rotational force called cutting torque acts on the clutch outer 56. Due to this rotational force, a rightward thrust force is generated in the clutch outer 56 via the helical spline portion 61, and the clutch outer 56 may move to the right and the pinion gear 6 may be disengaged from the ring gear 8. Therefore, in the engine starting device 1, the gear plunger 81 is held at the moving left end position (see the lower half of FIG. 1) by the electromagnetic attractive force applied to the sliding iron core 84, and the movement of the clutch outer 56 is restricted. Thereby, the rightward movement of the pinion gear 6 is restricted, and the detachment of the pinion gear 6 is suppressed.

  On the other hand, when the engine is started and the ignition key switch is turned off, the energization to the magnet switch 7 is stopped and the attractive force disappears. Then, the bracket plate 82 is pushed rightward by the urging force of the switch return spring 86, and the movable iron core 79 that has been held leftward by the suction force by the bobbin 78 is moved rightward. When the movable iron core 79 moves to the right, the switch shaft 45 also moves to the right, the switch plate 43 is separated from the conductive plate 41, and the contact is opened. Thereby, the power supply to the motor 2 is interrupted, the rotation of the drive shaft 4 is stopped, and the rotation of the clutch outer 56 is also stopped.

  When the rotation of the clutch outer 56 stops, the moving force in the axial direction due to the inertia mass disappears. For this reason, the clutch outer 56 moves to the right from the operating position to the stationary position along the helical spline portion 61 by the biasing force of the gear return spring 65 that has been compressed. At this time, the gear plunger 81 is also pushed by the clutch outer 56 to be in the upper half of FIG. The urging force of the gear return spring 65 is set to be larger than the urging force of the plunger spring 83 at this time. When the clutch outer 56 moves to the right, the pinion gear 6 also moves to the right, disengages from the ring gear 8, and returns to the upper half state of FIG.

  It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the example in which the present invention is applied to the motor having the structure in which the auxiliary pole 87 is added to the field magnet 26 is shown. However, the magnet fixing structure according to the present invention is applied to a motor that does not use the auxiliary pole 87. It is also possible to do. The motor 2 described above is a motor used as a drive source for the engine starter, but the present invention is not limited to the engine starter motor and can be widely applied to electric motors in general.

It is sectional drawing which shows the structure of the engine starting apparatus which uses the electric motor which is one Example of this invention as a drive source, The upper side from the centerline has shown the stationary state, and the lower side has shown the energized state. It is drawing which shows the structure of the magnet cover used with the electric motor of the engine starting apparatus of FIG. 1, (a) is a side view of a magnet cover, (b) is the left view. It is drawing which shows the structure of the motor housing of the state which fixed the magnet and the auxiliary pole with the magnet cover, (a) is the sectional drawing, (b) is a right view. It is drawing which shows the structure of a drain cover, (a) is the bottom view, (b) is a right view. It is explanatory drawing which shows the structure of the conventional magnet fixing | fixed part in the electric motor of a magnet field.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine starter 2 Electric motor 3 Reduction gear 4 Drive shaft 5 Overrunning clutch 6 Pinion gear 7 Magnet switch 8 Ring gear 11 Planetary gear mechanism 21 Motor housing 21a Inner peripheral surface 22 Armature 23 End cover 24 Gear cover 25 Set bolt 26 Magnet 27 Motor shaft 28 Armature core 29 Armature coil 31 Metal bearing 32 Bearing portion 33 Metal bearing 34 Commutator 35 Commutator piece 36 Brush holder 37 Brush housing portion 38 Brush 41 Conductive plate 41a First plate 41b Second plate 41c Insulating portion 42 Switch portion 43 Switch plate 44 Power terminal 45 Switch shaft 46 Internal gear unit 47 Drive plate unit 48 Internal ring 49 Metal bearing 51 Planetary gear 52 Base plate 53 Support pin 54 Metal bearing 55 Sun gear 56 Clutch outer 56a Boss part 56b Clutch part 57 Clutch inner 58 Roller 61 Helical spline part 62 Spline part 63 Stopper 64 Circlip 65 Gear return spring 66 Inner end wall 67 Clutch stopper 68 Clutch cover 69 Clutch washer 71 Shaft hole 72 Pinion gear metal 73 Spring accommodating portion 74 Fixed portion 75 Movable portion 76 Case 77 Coil 78 Bobbin 79 Movable iron core 81 Gear plunger 82 Bracket plate 83 Plunger spring 84 Sliding iron core 85 Metal bearing 86 Switch return spring 87 Auxiliary pole 88 Magnet cover 89 Flange 91 Holder portion 91a Outer peripheral surface 91b Shim portion 91c Protruding portion 92 Gap 93 Drain hole 93a Drain hole 94 Drain hole 95 Drain cover 96 Labyrinth portions 96a, 96b Separator 97 Snap fit portion 98 Communication port 99 Drain port
101 York
102 magnet
103 Auxiliary electrode
104 gap
105 Magnet holder
106 flange
107 Magnet cover
108 Protrusion

Claims (4)

A cylindrical metal yoke,
A plurality of magnets attached to the inner peripheral surface of the yoke;
A metal auxiliary pole disposed adjacent to the magnet;
A flange mounted on the inner side of the yoke and press-fitted and fixed to the inner peripheral surface of the yoke; and a cylindrical holder portion formed integrally with the flange; and between the holder portion and the inner peripheral surface of the yoke A magnet cover for holding the magnet at
An electric motor comprising: a drain hole formed in the flange of the magnet cover and disposed facing a gap formed in a portion where the magnet and the auxiliary pole do not exist.   The electric motor according to claim 1, wherein the yoke has a drainage hole communicating with the drain hole in the yoke.   The electric motor according to claim 2, wherein a drain cover having a labyrinth structure is attached to the outside of the drain hole. An engine starter that uses an electric motor as a drive source and engages a pinion rotated by the electric motor with an engine ring gear to start the engine,
The electric motor is
A cylindrical metal yoke,
A plurality of magnets attached to the inner peripheral surface of the yoke;
A metal auxiliary pole disposed adjacent to the magnet;
A flange mounted on the inner peripheral surface side of the yoke and press-fitted and fixed to the inner peripheral surface of the yoke, and a cylindrical holder portion formed integrally with the flange, the holder portion and the inner peripheral surface of the yoke A magnet cover for sandwiching the magnet between
An engine starter comprising: a drainage hole formed on the flange of the magnet cover and arranged to face a gap formed in a portion where the magnet and the auxiliary pole do not exist.

Images