Patent Application
20070252465
The above and other objects and features of the invention will be apparent from the detailed description of the preferred embodiments of the invention, which is described and illustrated with reference to the accompanying drawings, in which;
Now, preferred embodiments of the present invention will be described in detail with reference to
In this embodiment, on an inner periphery of the peripheral wall portion 11a of the rotor yoke 11, there are formed protrusions 11p and recesses 11r, which numbers correspond to the number of the permanent magnets 12 being made of rare earth magnet, so as to be arranged alternatively in the peripheral direction. Each stator side surface of the protrusions 11p is considered as a magnet attachment surface ms having same arc length (length measured in the peripheral direction of the rotor) as the permanent magnets to be bonded, and each permanent magnet 12 is bonded by adhesive to the magnet attachment surface ms of each protrusions 11p. Each permanent magnet 12 is provided so as to be extruded from the protrusion 11p, and the recesses 11r are formed to be opened between adjacent permanent magnets 12, 12 . . . . The rotor yoke 11 and the permanent magnets 12 constitute an outer-rotor-type magnet rotor 13.
A reference numeral 14 denotes an armature core being consisted of a steel lamination layer. The armature core 14 is comprised of an annular stator yoke 14a and a plurality (eighteen in
A boss portion 11b is provided at a center of a bottom wall portion of the cup-like rotor yoke 11. In order to mount the magnet rotor 13 on a prime mover such as an engine, a rotational shaft (not shown) of the prime mover is fitted with the boss portion 11b, and the boss portion 11b is fixed to the rotational shaft using suitable means.
The stator 16 is arranged inside of the magnet rotor 13 in a condition where a central axis of the stator 16 is consistent with that of the magnet rotor 13, and the annular stator yoke 14a of the armature core 14 is fixed to a case of the prime mover or the like. The magnet pole surface 14b1 on the tip of the salient pole portion 14b of the armature core 14 is opposed to the pole of the magnet rotor 13 with a predetermined air gap.
As described above, in the magneto generator according to the present invention, since the protrusions 11p and recesses 11r are arranged alternatively in the peripheral direction on the inner periphery of the peripheral wall portion of the rotor yoke 11, and the permanent magnets are bonded to the stator side surfaces of each protrusion 11p, the recesses 11r formed on the inner periphery of the rotor yoke is provided between the adjacent permanent magnets 12, 12, . . . . When the recesses 11r is thus provided, clearances C formed between the magnet pole surfaces of the armature core and the rotor yoke can be large at portions where the recesses 11r are formed. Therefore, it is possible to reduce a volume of pass through flux φ flowing, when occurring armature reaction, from the magnetic pole surfaces of the armature core 14 to the peripheral wall portion 11a of the rotor yoke though the air gap between the magnet pole surfaces of the armature core and the peripheral wall portion of the rotor yoke. Thus, reduction in eddy current loss which occurs at the peripheral wall portion 11a of the rotor yoke 11 and reduction in generator loss can be made.
In addition, temperature rise of the rotor can be prevented, and permanent magnets can be used with high magnetic flux density, since the eddy current loss generated in the rotor 13 can be reduced. Thus, the cost reduction can be accomplished by using smaller permanent magnets than conventional ones, in case where the requirement for the generator is the same as that for the conventional generator.
The surface area of the magnet can be small by downsizing the magnet furthermore, which makes it possible to prevent high temperature demagnetization from occurring. Therefore, performance of the magnet having high magnetic flux density can be fully utilized.
Further, since the reduction in temperature of the rotor 13 can prevent the temperature of the armature coil 15 arranged inside of the rotor from increasing, it is possible to prevent armature currents from being limited by the temperature rise of the armature coils 15. Also, it is possible to prevent a resistance value of a coil conductor from increasing by the temperature rise of the armature coils 15 and prevent copper loss generated in the armature coils from increasing, which can reduce the loss of the generator of the generator also.
In the above-described preferable embodiment of the invention, the number of the protrusions 11p and recesses 11r being provided on the inner periphery of the rotor yoke is made equal to that of the permanent magnets, and one permanent magnet is bonded to each protrusion 11p. However, the present invention is not limited to such constructions. For example, as shown in
Also, pole arc angle of a part of protrusions may become larger than that of other protrusions to bond a plurality of permanent magnets to the protrusions having larger pole arc angle. For example, as shown in
With such constructions shown in
Also, in the above-described each embodiment, although the permanent magnets 12 are bonded to all protrusions formed on the inner periphery of the peripheral wall portion of the rotor yoke, the present invention can be applied to a case where a part of magnets, which are supposed to be arranged in the same angular intervals, is omitted in order to make it possible to detect a particular rotational angle position of the rotor by utilizing a distortion of a waveform of output voltage of the generator, or in order to limit the output of the generator for preventing the output of the generator from increasing too large excessively. For example, as shown in
In the example shown in
In the present invention, when a part of permanent magnets which are supposed to be arranged in the same angular intervals is omitted, it is not necessarily required to constitute as shown in
As aforementioned, according to the present invention, since a plurality of protrusions and recesses are formed to be alternatively arranged in the peripheral direction on the inner periphery of the peripheral wall portion of the rotor yoke, and each permanent magnet is bonded to the stator side surface of the protrusion, it is possible to form a portion, which clearance formed between the magnet pole surface of the armature core and the rotor yoke is large, between adjacent permanent magnets. Therefore, it is possible to reduce a total amount of pass through flux passing from the magnet pole surface of the armature core to the peripheral wall portion side of the rotor yoke through the air gap when the armature reaction occurs, reduce the eddy-current loss generated at the peripheral wall portion of the rotor yoke, and thus increase the efficiency of the generator.
Also, according to the present invention, since an increase in temperature of the rotor by the eddy-current loss is prevented, the permanent magnets can be used with high magnetic flux density, and smaller permanent magnets can be used to reduce the cost if the requirement for the magnet generator is same as that for the conventional magneto generator.
Further, since surface areas of the magnets can be reduced by making the size of the magnets smaller, high temperature demagnetization can be difficult to occur, and thus the magnet performance can be fully utilized.
Furthermore, according to the invention, since the temperature rise of the armature coils arranged inside of the rotor can be prevented by enabling the temperature of the rotor to be lower, it is possible to downsize the generator without reducing generation outputs and easily manufacture the generator having desired functions at a low price, in cooperation with the reduction of loss, utilization of magnets with high magnetic flux density, and prevention of the high temperature demagnetization of the magnets.
Although some preferred embodiments of the invention have been described and illustrated with reference to the accompanying drawings, it will be understood by those skilled in the art that they are by way of examples, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined only to the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-123067 | Apr 2006 | JP | national |
