JP2673775B2 - Method for manufacturing rotor of magnet generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a rotor of a magnet generator .
The present invention relates to a manufacturing method , and more particularly, to a method for manufacturing a rotor of a magneto generator mounted on a small or special vehicle such as a motorcycle or a buggy, which is effective for improving a fixing structure of a permanent magnet.

[0002]

2. Description of the Related Art In general, a small or special vehicle such as a motorcycle or a buggy may use a magnet generator using a permanent magnet (hereinafter, referred to as a magnet) such as a ferrite magnet.

[0003] This type of magnet generator has a rotor composed of a plurality of magnets arranged and fixed at equal intervals on the inner periphery of a yoke, and coils wound around a plurality of radial locations on a core. The rotor is driven by the engine and rotates around the generated electron, so that an electromotive force is induced in each magnetic pole coil of the generated electron. ing.

Conventionally, as a rotor used in such a magnet generator, a case formed by connecting a plurality of magnet accommodating chambers having shapes corresponding to magnets with an upper open frame connected in a ring shape is fitted in a yoke. The magnet is inserted into each of the storage chambers of the case, and is clamped and fixed between partition walls between adjacent storage chambers, respectively.
Further, a cylindrical cover is fitted inside the case and the magnet, and a resin press ring is brought into contact with the outer flange of the cover. There is a type in which a plurality of magnets are integrated with a yoke by being swaged on a holding ring.

Further, as a conventional rotor of this type of magnet generator, there is one disclosed in JP-A-60-187248 and JP-A-61-280747.

The rotor of the former magnet generator includes an iron bowl, a magnet mounted on the inner periphery of the iron bowl, a magnet protection cover disposed on the inner peripheral surface of the magnet, a bottom surface of the iron bowl, a magnet and a magnet. A space for adhesive storage formed by the protective cover and a hole for injecting adhesive provided on the bottom surface of the iron bowl between the inner peripheral surface of the iron bowl and the magnet protective cover are provided.

The rotor of the latter magnet generator presses the cylindrical portion of the magnet protecting member against the inner circumferential surface of a plurality of arc-shaped magnets disposed on the inner circumferential surface of the iron bowl, and presses the flange of the magnet protecting member. The abutting portion contacts the opening end side end surface of each magnet to regulate the axial movement of each magnet, fixes the fixed portion of the magnet protection member to the bottom of the iron bowl, and forms a cylindrical iron bowl of the magnet protection member. The outer shape on the bottom side is tapered so as to be smaller than the inner diameter of each magnet array, and a bulging portion bulging in the outer diameter direction toward the space between the magnets is formed in the cylindrical portion of the magnet protection member. By doing
By fixing the magnet protection member to the iron bowl, each magnet is firmly fixed to the inner circumferential surface of the iron bowl. Further, the deformation of the magnet protection member at the time of press-fitting of the magnet protection member is absorbed by the bulging portion, and the outer shape of the fixed portion side of the cylindrical portion of the magnet protection member is not tapered so as to be smaller than the inner diameter of each magnet array. Thus, the deformation of the magnet protection member on the fixing portion side is reduced, and the magnet protection member can be securely fixed to the iron bowl by the fixing portion.

[0008]

However, in the rotor of the conventional magnet generator in which the magnet case is used, not only the number of parts and the number of assembling steps are increased due to the magnet case, but the magnet is magnetized. Since the magnets are press-fitted into the case, strict control of the magnet dimensions is required.Also, the allowance for absorbing the dimensional variation of the magnets, the magnet case and the crimping allowance, and the axial direction of the rotor of the magnet generator The dimension of becomes longer.

Further, in the rotor of the magnet generator and the manufacturing method thereof proposed in Japanese Patent Laid-Open No. 60-187248, since an adhesive is used, workability is deteriorated.

Further, in both of the rotors of the magnet generator proposed in Japanese Patent Laid-Open No. 60-187248 and Japanese Patent Laid-Open No. 61-280747, the axial positioning of each magnet is the bottom of the iron bowl. Since it is performed on the wall side, variations in the axial dimension of each magnet are absorbed on the opening side of the iron bowl, and as a result, the axial dimension of the rotor of the magnet generator becomes long. In order to store the generator coil of the magnet generator in the restricted space inside the yoke of the rotor, the stator core is positioned on the opening side of the yoke that absorbs the variation in the axial dimension of each magnet. However, the variation in the output of the generator also becomes large.

An object of the present invention, it is possible to fix the magnet without using a magnet case and the adhesive, the manufacturing method of a rotating terminal of the magneto generator can be shortened axial dimension as much as possible To provide.

[0012]

A method of manufacturing a rotor for a magneto generator according to the present invention comprises a plurality of magnets on the inner circumference of a substantially bowl-shaped yoke.
The magnets are arranged at intervals,
Magnet generator with a cylindrical cover fitted inside
In the method for manufacturing a rotor, the closing of the yoke (11) is performed.
In a plurality of through holes (17) previously opened in the closing wall (14)
Floatingly supported by spring (45)
The magnet axial support jig (44) is
The steps of inserting each and the inside of the yoke (11)
The magnet shaft is housed in the magnet (20) group.
To be placed on the direction support jig (44)
So that each of the magnets (20) is in the axial direction of the magnet.
Flow freely in the axial direction by the support jig (44)
And a step of supporting the magnet (20)
By inserting the cover (30) inside the
The cylindrical wall (31) of the cover (30) expands radially outward.
Between the magnets (20) and (20) that are taken out and adjacent to each other
Forming a first bulge (37) in the space of
The inner collar (33) of the cover (30) closes the yoke.
Fixing to the wall (14), and the cover cylinder wall (3
1) is the yoke closing wall (14) and the magnet (2)
0) outward toward the space between the yoke closing wall side end surface (26)
At least the yoke of each magnet (20) is closed.
A second bulge (38) is formed by bulging at the end face on the wall side.
It is characterized by comprising the following steps:

[0013]

According to the above-mentioned means, while the outer flange portion of the cover is in contact with the upper surface of each magnet, the yoke closing wall side portion of the cylindrical wall of the cover is bulged outward in the radial direction. The magnets can be fixed in a state of being sandwiched by the outer flange portion of the cover and the second bulging portion bulged and molded on the yoke closing wall portion of the cover cylinder wall. As a result, the axial positions of the magnets are aligned on the outer collar portion of the cover, and the dimensional variations in the height direction of the magnets are absorbed on the closed wall side of the yoke. The axial length of the rotor can be shortened.

[0014]

1 shows a rotor of a magneto-generator according to an embodiment of the present invention, (a) is a plan view, (b) is (a).
FIG. 4 is a front sectional view taken along line bb of FIG. FIG. 2 shows a yoke, (a) is a partially omitted plan view, (b) is a front sectional view taken along the line bb of (a), and (c) is a partially omitted bottom view. 3A and 3B show a cover, wherein FIG. 3A is a partially omitted plan view, FIG. 3B is a front sectional view, and FIG. 3C is a partially omitted bottom view. Figure 4 and later are each explanatory views of a manufacturing method of the magneto generator which is an embodiment of the present invention.

In the present embodiment, the rotor of the magneto-generator according to the present invention comprises a yoke, a plurality of magnets and a cover.

The yoke 11 is integrally formed in a substantially bowl shape whose upper surface is opened and whose lower surface is closed by a magnetic material. A reluctor 13 has a cylindrical wall 12 having a predetermined width in the circumferential direction and the axial direction. Projected outward in the direction. A shaft hole 15 for inserting a boss (not shown) directly connected to the engine is formed in the lower surface blocking wall 14 of the yoke 11 at the center, and a yoke positioning described later is provided at a position outside the shaft hole 15. Circular hole used to attach jig 1
A pair of 6 are provided on the concentric circles with a phase difference of 180 degrees. Further, the closing wall 1 of the yoke 11
A plurality of elliptical holes 17 (12 in the present embodiment) for inserting a magnet positioning jig, which will be described later, are formed in the outer peripheral portion of No. 4 on the concentric circles at equal intervals in the circumferential direction. There is.

Further, the bottom surface of the closing wall 14 of the yoke 11 is provided with a plurality of convex portions 18 (8 in this embodiment) for fixing the cover, and a group of circular holes 16 and a group of elliptical holes 17 are provided. They are arranged at equal intervals in the circumferential direction on concentric circles between them, and a part of the closing wall 14 is pushed up from the outer surface so as to project inward in the axial direction. This convex portion 18 covers the cover as will be described later. It is configured so that it can be caulked by being inserted into a fixing hole that is provided so as to project.

The closed wall 14 of the yoke 11 is provided with a plurality of female screw holes 19 for attaching a cooling fan, which are concentrically formed around the group of circular holes 16 at equal intervals in the circumferential direction. Further, no crimping margin is provided at the opening edge of the cylindrical wall 12 of the yoke 11.

The magnet 20 has a height equal to or less than the depth of the yoke 11 and is integrally formed into a substantially rectangular parallelepiped having a circular arc shape curved along the inner circumference of the yoke 11 in the width direction. Inclined surface portions 23 are formed on both left and right ends of an arc-shaped inner peripheral surface (hereinafter, referred to as abdominal surface) 21 of the magnet 20 so as to approach an outer peripheral surface (hereinafter, referred to as a rear surface) 22 as they go to the left and right ends. Has been done. The rising side surfaces 24 and 24 on both sides are formed so as to be perpendicular to a tangent to a normal line passing through the center of the yoke 11, and the upper surface 25 and the lower surface 26 are formed parallel to each other.

The cover 30 is made of a metal material such as a thin iron plate and is integrally formed by drawing and pressing. The cover 30 is formed into a cylindrical shape which is press-fitted into a cylinder formed by a magnet 20 group described later. At one end (hereinafter, referred to as an upper end) of a cylindrical wall 31 of the cover 30, an outer flange portion 32 is formed in a circular donut shape projecting outward in a radial direction.

Before assembling, an inner collar portion 33 is integrally formed in a circular donut shape at the lower end of the cylindrical wall 31 of the cover 30. The inner diameter of the inner flange portion 33 is smaller than the arrangement diameter of the group of convex portions 18 arranged on the yoke 11 and equal to or slightly larger than the arrangement diameter of the circular holes 16, 16. At the radially intermediate portion of the inner flange portion 33, the same number of fixing holes 34 as the number of the projections 18 of the yoke 11 (eight in the present embodiment), each of which is aligned with the group of the projections 18 of the yoke 11, are provided. And each fixing hole 34
Are formed so that the respective projecting portions 18 can be inserted.

A notch 3 is formed on the inner peripheral edge of the inner flange 33.
5 (eight in this embodiment) are formed in a substantially semicircular shape.
One group of circular holes 16 and one group of female screw holes 19 can be appropriately escaped. Further, a rigidity imparting portion 36 is formed on the inner peripheral edge of the inner flange portion 33 by bending and raising the entire periphery including the cutout portion 35. The rigidity imparting portion 36 is formed by bending the inner peripheral edge of the inner flange portion 33 inward in the axial direction to a constant height over the entire circumference by drawing or the like, and imparts sufficient rigidity when the cover 30 described later is press-fitted. It has become.

Next, a method of manufacturing the rotor of the magneto-generator, which is an embodiment of the present invention, will be described in the case of using each component having the above-mentioned configuration. This description, detailed configuration of the rotor of the magneto generator according to an embodiment of the present invention is to both clear.

First, as shown in FIGS. 4A and 5, the yoke 11 is set on the base 41 of the manufacturing apparatus 40 for the rotor of the magnet generator. At this time, the yoke 1
A pair of yoke positioning jigs 42, 42 are respectively inserted through the pair of circular holes 16, 16 in 1. Also,
A magnet circumferential positioning jig (hereinafter, referred to as a magnet first jig) 43 and a magnet axial support jig (hereinafter, referred to as a magnet second jig) 44 are inserted into the oval holes 17 group. It

Here, the second magnet jig group 44 is floatingly supported on the base 41 by springs 45, respectively, and is movable in the vertical direction. The magnet first jig 43 group is the magnet 20.
The same number (4 in this embodiment) as the elliptical holes 17
They are arranged at equal intervals in the circumferential direction on a circle concentric with the array diameter of the group. Further, shoulders 43a, 43a are formed on both side edges in the circumferential direction of each magnet first jig 43, respectively. The other magnet second jig 44 group has an oval hole 17
The number obtained by subtracting the number of magnets 20 from the number of groups (8 in this embodiment) is arranged on both sides of each magnet first jig 43 concentrically with the array diameter of the group of oblong holes 17. It is set up.

Subsequently, as shown in FIGS. 4A and 5, a plurality (four in this embodiment) of magnets 20 are arranged in a circular ring shape in the yoke 11. At this time, the magnet 20 is in a state in which the back 22 is in contact with the inner peripheral surface of the yoke 11, the lower surface 26 of the two the magnet
While being respectively placed on the second jig 44 for magnets , both rising side surfaces 24, 24 are engaged with the shoulder portions 43a, 43a of the first jigs 43, 43 for magnets on both sides, respectively. In this state, the magnet 20 is the magnet
Positioning is performed in the circumferential direction by the first jig 43 for power supply . Further, the magnet 20 is the second jig 4 for the magnet .
It is located at the upper limit by 4, 44 and is in a state of being floatingly supported in the vertical direction.

Next, as shown in FIGS. 4A and 6, the cover 30 is fitted inside the group of magnets 20 by the fitting tool 50. At this time, since the rigidity imparting portion 36 is formed on the inner flange portion 33 of the cover 30, the cover 30 is properly fitted. In the state after the fitting, the cover 30 has the inner flange portion 33 with the closing wall 14 of the yoke 11.
Is in contact with the bottom surface of the magnet, and the outer flange portion 32 is in contact with the upper surface 25 of the magnet group 20. Further, by press-fitting the cover 30, the first bulge portion 37 is formed between the magnets 20 and the magnets 20 are relatively positioned in the circumferential direction and prevented from rotating.

Here, the outer diameter of the fitting tool 50 is formed in a two-step cylindrical shape having a small diameter on the lower side and a large diameter on the upper side, and the small diameter portion 51 on the lower side is substantially the same as the inner diameter of the cylindrical wall 31 of the cover 30. The diameter of the large-diameter portion 52 on the upper side is substantially the same as the outer diameter of the outer collar portion 32 of the cover 30.

The fitting tool 50 has the same number of yoke positioning holes 53 as the circular holes 16 (two holes in this embodiment), which are provided in the axial direction. The yoke positioning jigs 42 are relatively inserted into the respective yoke positioning holes 53, so that the fitting tool 50, the yoke 11 and the magnet 20 group are positioned with respect to each other.

In the fitting tool 50, the same number of insertion holes 54 as the projections 18 of the yoke 11 (8 in this embodiment) are provided in the axial direction. An annular groove 55 is provided on the lower surface of the small diameter portion 51 of the fitting 50 so as to be able to accommodate the rigidity imparting portion 36 of the cover 30. According to the above-described positioning state, the protrusions 18 are inserted into the insertion holes 54, and the rigidity imparting portion 36 is inserted into the annular groove 55, respectively, and the fitting tool 50 to the protrusions 18 and the rigidity imparting portion 36 is inserted. Interference has been avoided.

As shown in FIGS. 4 (b) and 7, the caulking pin is inserted through the insertion hole 54 of the fitting 50 and the yoke 11 inserted through the fixing hole 34 of the cover 30.
The protruding end of the convex portion 18 is caulked. The group of protrusions 18 after the caulking process causes the cover 30 to be fixed in a circular ring shape to the closing wall 14 of the yoke 11 over the entire circumference of the inner flange portion 33, and thereafter, the fitting tool 50.
Is dismantled. In this state, the magnet group 20 is circumferentially positioned and prevented from rotating with respect to the yoke 11.

Next, after the fitting tool is removed, FIG.
As shown in FIG. 8C and FIG. 8, the plastic tool 60 is inserted inside the cover 30 to form a space between the yoke closing wall of the cylindrical wall 31 of the cover 30 and the yoke closing wall side end surface portion of the magnet. A second swelling portion 38 is formed so as to bulge outward in a ring shape, or at least on the yoke closing surface side end surface portion of each magnet, and the magnets 20 are positioned in the axial direction.

Here, the outer diameter of the plastic tool 60 is formed in a two-step cylindrical shape having a small diameter on the lower side and a large diameter on the upper side, and the small diameter portion 61 on the lower side is substantially the same as the inner diameter of the cylindrical wall 31 of the cover 30. The upper diameter portion 62 on the upper side is formed to have substantially the same diameter as the outer diameter of the outer collar portion 32 of the cover 30.

In the plastic tool 60, the same number of yoke positioning holes 63 as the circular holes 16 (two holes in this embodiment) are provided in the axial direction. Each yoke positioning hole 63
The respective positioning jigs 42 for the yokes are relatively inserted into each other, whereby the positioning of the plastic tool 60, the yoke 11 and the magnet 20 group is ensured.

An elastic body portion 64 made of urethane resin or the like is provided on the lower surface of the small diameter portion 61 of the plastic tool 60. The elastic body portion 64 includes the lower surface of the small diameter portion 61 of the plastic tool 60 and the closing wall 14 of the yoke 11. When compressed in the axial direction between them, they are formed so as to be able to bulge and deform outward in the radial direction all around, or at least at the yoke closing wall side end surface portion of each magnet.

When the elastic body portion 64 of the plastic tool 60 is pressed against the bottom surface of the closing wall 14 of the yoke 11, the elastic body portion 64 bulges and deforms outward in the radial direction, so that the inner collar portion of the cylindrical wall 31 of the cover 30 is deformed. Extrude the area around 33 radially outward,
The second bulging portion 38 of the magnet is formed in the space between the yoke closing wall and the yoke closing wall side end surface portion of the magnet.

When the second bulging portion 38 of the cover 30 is bulged, the lower surface of the large diameter portion 62 of the plastic tool 60 pushes down the outer flange portion 32 of the cover 30, so that the second bulging portion 3 is formed.
8 will be formed with excess thickness of the cylindrical wall 31 without coming depressed be formed stretching the cylindrical wall 31 of the cover 30 station unit basis. Therefore, due to the bulging of the second bulging portion 38 , the strength of the second bulging portion 38 does not decrease due to an extreme reduction in plate thickness.

On the other hand, when the lower surface of the outer flange portion 32 of the pushed down cover 30 contacts the upper surface 25 of each magnet 20, each magnet 20 is pushed upward by each second magnet jig 44. Since the magnets 20 are floatingly supported, the height of each magnet 20 is the lower surface of the outer collar portion 32 of the cover 30, that is, the plastic tool 60.
The large-diameter portion 62 has a leveled lower surface.

Then, when the plastic tool 60 is inserted with a certain size and the compression of the elastic body portion 64 in the axial direction is stopped, the heights of the magnets 20 are aligned with the lower surface of the outer flange portion 32 of the cover 30. The outer flange portion 32 and the second bulge portion 3 in the closed state.
It will be clamped between 8 and 8 and fixed.

After that, the plastic tool 60 is extracted upward from the inside of the cover 30. Next, the yoke 11 is the base 4
1 Reset from above. Through the above steps, the rotor of the magneto generator shown in FIG. 1 is manufactured.

[0041]

As described above, according to the present invention,
The following effects are obtained. (1) A first bulge portion formed by bulging a tubular wall of the cover outward in the radial direction is formed between adjacent magnets, and the magnets are fixed in the radial direction, while each magnet is axially fixed. With the outer flange part of the cover in contact with the upper surface, the yoke blocking wall side part of the cover's cylinder wall is bulged outward in the radial direction, so that each magnet is covered with the outer flange part of the cover and the cover cylinder wall. It can be fixed in a state of being sandwiched by the second bulging portion that is bulged and formed on the yoke closing wall side portion.

(2) According to the above (1), the height positions of the magnets are aligned on the outer flange portion of the cover, and the dimensional variations in the height direction of the magnets are absorbed on the closing wall side of the yoke. Therefore, the axial length of the rotor of the magneto generator can be shortened.

(3) According to the above (1), since the magnet case can be eliminated, the number of parts and the number of work steps can be reduced, and the step of press-fitting the magnet into the magnet case is eliminated. The strictness of the dimensional control of the magnet can be eased. Further, the axial length of the rotor of the magneto generator can be shortened by the amount by which the pressing ring is eliminated.

(4) According to the above (1), since the winding and crimping margin portion at the opening end of the yoke can be omitted, the axial length of the rotor of the magnet generator can be further shortened.

(5) Since the positions (2), (3) and (4) of the rotor of the magneto generator in the axial direction of the magnet and the position of the magnet core in the magnet axial direction can be kept constant, It is possible to suppress variations in the performance of the magneto generator.

(6) By pressing the cover into the magnet group while temporarily positioning the magnet on the yoke with the jig, the press-fitting of the cover can be stabilized.

(7) When the bottom portion of the cover's cylinder wall is bulged outward in the radial direction, the cover is pushed down and the bulging margin is supplied from above, whereby excessive pulling is applied to a part of the cover cylinder wall. Since it is possible to prevent the stress from acting, it is possible to prevent the strength of the second bulging portion of the cover from being significantly reduced.

[Brief description of the drawings]

FIG. 1 shows a rotor of a magneto-generator according to an embodiment of the present invention, (a) is a plan view, (b) is bb of (a).
It is a front sectional view along a line.

FIG. 2 shows a yoke, (a) is a partially omitted plan view, (b) is a front sectional view taken along line bb of (a),
(C) is a partially omitted bottom view.

FIG. 3 shows a cover, (a) is a partially omitted plan view, (b) is a front sectional view, and (c) is a partially omitted bottom view.

4A and 4B show a method of manufacturing a magneto-generator according to an embodiment of the present invention, in which FIG. 4A is a partially cut exploded perspective view showing a cover inserting step, and FIG. 4B shows a cover fixing step. Partially cut perspective view, (c) is a partially cut perspective view showing the cover bulging step.

FIG. 5 is an enlarged partial front sectional view showing a magnet positioning step.

FIG. 6 is an enlarged partial front sectional view showing a cover inserting step.

FIG. 7 is a front sectional view showing a fixing step of the cover.

FIG. 8 is a front sectional view showing a cover bulging step.

[Explanation of symbols]

11 ... Yoke, 12 ... Cylinder wall, 13 ... Retractor, 14 ... Closed wall, 15 ... Shaft hole, 16 ... Circular hole, 17 ... Oval hole ( through
Hole), 18 ... protruding portion, 19 ... female screw hole, 20 ... magnet, 21 ... inner circumferential surface of the arcuate (ventral surface), 22 ... outer circumferential surface (back surface), 23 ... inclined surface, 24 ... rising side, 2
5: Upper surface (yoke opening side end surface) , 26: Lower surface (yoke closed)
塞壁side end surface), 30 ... cover, 31 ... cylinder wall, 32 ... outer flange portion, 33 ... inner-side flange portion 34 ... fixing hole, 35 ... notch,
36 ... stiffening portion, 37 ... first bulge portion, 38 ... second bulging portion, 40 ... manufacturing apparatus of a rotating element of the magneto generator, 41 ...
Base 42, yoke positioning jig 43, magnet circumferential positioning jig (first jig for magnet) 43a
... shoulder, 44 ... magnet axial support jig (second jig for magnet), 45 ... spring, 50 ... fitting tool, 51
... small diameter portion, 52 ... large diameter portion, 53 ... yoke positioning hole, 5
4 ... Insertion hole, 55 ... Annular groove, 60 ... Plastic tool, 61 ... Small diameter part, 62 ... Large diameter part, 63 ... Yoke positioning hole, 64 ... Elastic body part.

Claims (1)

(57) [Claims] 1. A plurality of magnets are provided on the inner circumference of a substantially bowl-shaped yoke.
The nets are arranged at intervals, inside the magnet
Rotor of magnet generator with cylindrical cover fitted in
In the manufacturing method of (1), the blocking wall (14) of the yoke (11) was previously opened.
A plurality of through holes (17) are closed by springs (45).
Rotating supported magnet axial support jig (4
4) are respectively inserted from the outside of the closing wall , and the magnet (20) group is housed in the yoke (11).
And placed on the magnet axial support jig (44).
Each of the magnets (2
0) is provided by the magnet axial support jig (44).
A process of floatingly supporting the movable unit in the axial direction, and the cover (30) inside the magnet (20) group.
By inserting the cylinder wall of the cover (30).
(31) is bulged radially outward, and the adjacent mug
In the space between the nets (20), (20), the first bulge (3
7) is formed, and the inner collar portion (33) of the cover (30) closes the yoke.
The step of being fixed to the closing wall (14), and the cover cylinder wall (31) being the yoke closing wall (14).
An end surface (26) of the magnet (20) on the side of the yoke closing wall
At least each of the magnets outward in the space between
The second bulge is bulged at the end surface of the yoke closing wall of (20).
And a step of forming the protrusion (38).
A method for manufacturing a rotor of a characteristic magneto-generator.