JPH02197243A - Small-sized generator - Google Patents

Abstract

PURPOSE:To raise a generating efficiency and to lighten an energy burden at the time of lighting a headlamp by connecting the bottom faces of first and second cores constituting a stator by a cylindrical pole core having a large thickness. CONSTITUTION:The bottom faces 31b, 32b of a first core 31 and a second core 32 are connected by a cylindrical pole core 5 having a large thickness. In the magnetic paths of the bottom face 31b of first core 31 pole core 5 and the pole core 5 bottom face 32b of second core 32, a magnetic flux is bent with a relatively large curvature to decrease the loss of magnetic flux in the pole core 5. Also, because said pole core 5 has a large thickness, the magnetic path of said bottom faces 31b, 32b shortens to decrease an iron loss. Further, when said pole core 5 is molded from amorphous metal, magnetic iron powder or high silicon steel, the loss of skin effect in the pole core 5 is decreased still more.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small generator mounted on a bicycle as a power source for, for example, a headlamp.

[Prior art and its problems]

When riding a bicycle at night, using batteries as a power source for headlights has a short lifespan and must be replaced frequently, so bicycles are often equipped with small generators. Various structures of small generators used for this purpose have been proposed and put into practical use.
For example, the rotor is made of an elliptical cylindrical permanent magnet with north and south poles arranged alternately in the axial direction, and the stator is made of a bottomed cylindrical ferrous iron magnet with a plurality of short teeth arranged in the axial direction. It is constructed by combining a core and a bottomed cylindrical second iron core in which a plurality of long teeth are arranged in the axial direction, and these short teeth and long teeth are arranged on the outer periphery of the rotor and rotate as the rotor rotates. A device in which electric power is induced in a coil wound around the connecting portion between the bottom surfaces of the first iron core and the second iron core has been put into practical use. FIG. 5 shows a cross-sectional view of a conventionally known stator, and the first iron core 31 and the second iron core 32 have a plurality of short teeth 31a and long teeth 32a extending in the axial direction from the bottom surface 31b and the bottom surface 32b, respectively. It extends into a cylindrical shape with a bottom. As shown in FIG. 2, the short teeth 31a and the long teeth 32a are combined so as to be arranged alternately, and a cylindrical connecting portion 33 is integrally provided on the bottom surface 31b of the first iron core 31. The connecting portion 33 is fitted into a hole in the bottom surface 32b of the second iron core 32 and fixed. Further, a coil 4 is wound around the connecting part 33, and the rotor arranged in the short teeth 31a and the long teeth 32a rotates, and the N and S poles of the rotor are connected to the short teeth 31.
When the magnetic flux alternately passes through the positions close to the long teeth 32a and the long teeth 32a, the magnetic flux flows from the short teeth 31a to the bottom surface 31b to the connecting portion 3.
Electric power is induced in the coil 4 by reciprocating the magnetic path of 3→bottom surface 32b→long teeth 32a at a frequency corresponding to the running speed of the bicycle.

Here, since the first iron core 31 has a complicated shape,
The first iron core 31 and the second iron core 32 are made of structural iron plates with excellent workability or have a silicon content of 1% or less and a wall thickness of 1%.
It is molded from a low-silicon iron plate with a thickness of approximately 1.5 mm, but in the magnetic path, the magnetic flux flows from the bottom surface 31b to the connecting portion 33 and from the connecting portion 33 to the bottom portion 32b, and it is necessary to bend at a right angle.
At this point, eddy currents occur due to the disturbance of the magnetic flux, increasing iron loss. Furthermore, a low-silicon iron plate with a silicon content of about 1% has a skin effect loss that increases as the frequency increases, but this skin effect loss particularly has an adverse effect on the connection part 33 where the magnetic flux exhibits complex behavior. There is a problem that the magnetic flux passing through the portion 33 is reduced. Therefore, the efficiency of the generator decreases, and only low power generation efficiency can be obtained. Lamps with a rating of about 3W are used for bicycle headlights, but if the efficiency of a small generator is 20%, it would require 15W of power to light a 3W lamp. On the other hand, the power required to run a bicycle is said to be about 75 to 150W.
The proportion of power required to turn on the headlights is extremely large. Therefore, turning on a small generator to turn on the headlights makes the pedals heavy, and even though the small generator is installed, you may end up driving without using it. It was extremely dangerous.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a compact generator with high power generation efficiency and a light energy burden when the headlights are turned on.

[Structure of the invention and its effects]

The structure of the present invention includes a rotor made of a cylindrical permanent magnet in which N poles and S poles are arranged alternately in the axial direction, and a ferrous iron rotor in the shape of a bottomed cylinder in which a plurality of short teeth are arranged in the axial direction. A core and a bottomed cylindrical second iron core in which a plurality of long teeth are arranged in the axial direction are combined, and the short teeth and long teeth have a stator arranged on the outer periphery of the rotor, and the rotation of the rotor This is a small generator in which electric power is induced in a coil wound around the connection between the bottom surfaces of the first iron core and the second iron core, and the bottom surfaces of the first iron core and the second iron core are thick. It is characterized by being connected by a thick cylindrical pole core.

That is, since the bottom surfaces of the first iron core and the second iron core that constitute the stator are connected by a thick cylindrical pole core, the bottom surface of the first iron core → the pole core and the pole core.
→The magnetic flux can be bent with a relatively large radius of curvature in the magnetic path at the bottom of the second iron core. Therefore, there is less disturbance in the magnetic flux, and iron loss in this portion can be reduced. In addition, since the pole core is a cylindrical body separate from the first and second iron cores, it can be easily molded even from materials with poor workability, and can be molded from amorphous metal, magnetic iron powder, or high-silicon steel. This reduces skin effect loss in the pole core, where magnetic flux behaves in a complex manner, and allows a large amount of magnetic flux to pass through. Therefore,
Power generation efficiency is improved and the energy burden when turning on the headlights is reduced.

〔Example〕

The present invention will be specifically described below based on embodiments shown in the drawings.

Figure 1 shows a small generator mounted on a bicycle.
is rotatably supported, and a pressure contact piece 13 is attached to the tip of the main shaft 12 for pressure contact with the axle of the bicycle. A rotor 2 is connected to the rear end of the main shaft 12 via a connecting plate 14.
is installed. The rotor 2 is a cylindrical permanent magnet, and has six north and south poles in the axial direction, as shown in FIG.
The poles are arranged alternately. A stator 3 is arranged on the outer periphery of the rotor 2, and the stator 3 is connected to the first iron core 3.
1 and a second iron core 32. The first iron core 31 and the second iron core 32 are made of low-silicon iron plates with a wall thickness of 1 mm and are formed into a cylindrical shape with a bottom.
Six short teeth 31a to six long teeth 32a each extend in the axial direction from b and 32b. Then, the first iron core 31 and the second iron core 32 are combined as shown in FIG. 2, and the short teeth 31a and the long teeth 32a are arranged alternately and arranged at a predetermined interval on the outside of the rotor 2. . Here, the bottom surface 31b of the first iron core 31 and the bottom surface 32b of the second iron core 32 are connected and fixed, but the inner pole core 6 is fitted into the center hole of the cylindrical pole core 5, and both ends of the inner pole core 6 are inserted into the center hole of the cylindrical pole core 5. are inserted into holes in the bottom surfaces 31b and 32b and fixed by caulking. The pole core 5 is, for example, a cylindrical body with an outer diameter of 17 mmφ, a wall thickness of 4 mm, and a length of 10 mm, and the wall thickness is larger than that of the iron cores 31 and 32, and both end surfaces are in close contact with the bottom surfaces 31b and 32b. ing. The material of the pole core 5 is a soft magnetic material such as soft ferrite, but preferably an amorphous metal with low skin effect loss, magnetic iron powder, or high silicon steel with a silicon content of 5% or more. A coil 4 is wound around its outer periphery.

Therefore, when riding at night, the pressure contact piece 13 is pressed against the axle of the bicycle. Therefore, the rotor 2 rotates at a rotation speed corresponding to the running speed of the bicycle, but at this time, as shown in FIG. , the magnetic flux reciprocates through the short teeth 31a → bottom surface 31b → pole core 5 → bottom surface 32b → long teeth 32a at a frequency 10 times the rotation speed of the rotor 2, and electric power is induced in the coil 4. The headlights will turn on.

Here, the bottom surfaces 31b, 3 of the first iron core 31 and the second iron core 32 are
2b are connected by the thick cylindrical pole core 5, the magnetic flux is compared in the magnetic path from the bottom surface 31b of the first iron core 31 to the ball core 5 and the ball core 5 to the bottom surface 32b of the second iron core 32. The pole core 5 can be bent with a large radius of curvature, and the magnetic flux in the pole core 5 is unlikely to decrease. Therefore,
There is little disturbance in the magnetic flux, and iron loss in this area can be reduced. Also.

Since the wall thickness of the pole core 5 is large, the magnetic path of the bottom surfaces 31b and 32b is shortened among the magnetic paths described above, and iron loss is reduced accordingly. Furthermore, if the pole core 5 is made of amorphous metal, magnetic iron powder, or high-silicon steel, the skin effect loss in the pole core 5, which exhibits complex behavior due to mutual interference between magnetic fluxes reciprocating at frequencies of several hundred hertz, can be reduced. , a lot of magnetic flux can pass through. FIG. 4 shows the power generation efficiency of the conventional example shown in FIG. The power generation efficiency is significantly improved compared to the previous model, and the effect is especially great when driving at high speeds. Therefore, the energy burden when the headlights are turned on is light and the pedals can be rotated easily, making it easy to comply with the duty to turn on the lamps when driving at night.

〔Effect of the invention〕

As explained above, in the small generator of the present invention, the bottom surfaces of the first iron core and the second #i core constituting the stator are connected by a thick cylindrical pole core. In addition, by molding the pole core with amorphous metal, magnetic iron powder, or high-silicon steel, the skin effect loss in the pole core, where magnetic flux behaves in a complex manner, is reduced, allowing a large amount of magnetic flux to pass through. Therefore, it is possible to create a small generator with high power generation efficiency and a light energy burden when the headlights are turned on.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the embodiment of the present invention, Fig. 2 is a perspective view of the stator, Fig. 3 is an explanatory diagram of the relationship between the rotor and teeth, Fig. 4 is an explanatory diagram of data, and Fig. 5 is an explanatory diagram of the conventional example. It is. 1...Casing 12...Main shaft 13...Impression piece 2...Rotor 3...Stator 31...First iron core 31a...Short teeth 31b...Bottom surface 3
2. Second iron core 32a... Long teeth 32b...
Bottom surface 4...Coil 5...Ball core 6...Inner ball core Applicant Sailor Fountain Pen Co., Ltd. Yaskawa Control Co., Ltd.

Claims (4)

[Claims] (1) A rotor consisting of a cylindrical permanent magnet with N and S poles arranged alternately in the axial direction, a first iron core in the form of a cylinder with a bottom and a plurality of short teeth arranged in the axial direction; A bottomed cylindrical second iron core in which a plurality of long teeth are arranged in the axial direction is combined, and the short teeth and long teeth have a stator disposed around the outer periphery of the rotor, and as the rotor rotates. A small generator in which electric power is induced in a coil wound around a connecting portion between the bottom surfaces of the first iron core and the second iron core, the bottom surfaces of the first iron core and the second iron core being fleshy. A small generator characterized by being connected by a thick cylindrical pole core. (2) The small-sized generator according to claim 1, wherein the pole core is made of an amorphous metal. (3) The small-sized generator according to claim 1, wherein the pole core is made of magnetic iron powder. (4) The small-sized generator according to claim 1, wherein the pole core is made of high silicon steel.