JP3690261B2 - Rotating electric machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a permanent magnet field type rotating electrical machine, and more particularly to a permanent magnet field type rotating electrical machine with a sub-pole.
[0002]
[Prior art]
As this type of rotating electric machine, a technique disclosed in Japanese Patent Publication No. 57-12380 is known. The rotating electrical machine disclosed in this publication is composed of a permanent magnet having a pair of magnetic pole faces at the opposite end faces in the circumferential direction between the poles of each main magnetic pole and having the same polarity as the magnetic pole face on the armature side of the adjacent main magnetic pole. The sub magnetic pole is arranged to suppress the leakage magnetic flux between the main magnetic poles and increase the effective magnetic flux reaching the armature from the main magnetic pole through the gap. With this technique, the output can be increased without changing the external dimensions of the rotating electrical machine. In addition, by using this technique, the outer dimensions can be reduced without changing the output of the rotating electrical machine.
[0003]
[Problems to be solved by the invention]
During operation of the rotating electrical machine, a current flows through the armature, and a magnetic flux distribution is generated due to the armature reaction. FIG. 6 shows a developed view of the field and armature of the rotating electric machine and the magnetic flux distribution due to the corresponding armature reaction. As shown in FIG. 6, this magnetic flux distribution has a triangular wave shape, and is maximized between adjacent main magnetic poles, that is, at the position of the sub magnetic pole. As is clear from FIG. 6, the magnetic flux acting on the sub magnetic pole is larger by ΔH than the magnetic flux acting on the main magnetic pole. That is, the sub-magnetic pole is most strongly affected by the armature reaction. A large magnetic flux due to an armature reaction different from the magnetization direction of the sub magnetic pole acts on the sub magnetic pole to demagnetize the sub magnetic pole. When the armature reaction is large, irreversible demagnetization occurs in the auxiliary magnetic pole. When irreversible demagnetization occurs in the secondary magnetic pole, even if the armature reaction is removed, the magnetic flux density of the secondary magnetic pole remains lowered and does not return. Therefore, the function of suppressing the leakage magnetic flux between the main magnetic poles to be fulfilled by the sub magnetic pole is lowered, and the output of the rotating electrical machine may be lowered.
[0004]
The present invention has been made in view of the above points, and by an easy means of appropriately selecting the magnetic characteristics of the sub-pole, preventing irreversible demagnetization of the sub-pole when the maximum armature reaction occurs, An object of the present invention is to provide a highly reliable rotating electrical machine that maintains the leakage magnetic flux suppressing function between main magnetic poles fulfilled by the sub-magnetic pole and does not cause a decrease in output.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention employs the following technical means.
[0007]
In the rotating electrical machine according to claim 1 of the present invention, the magnetic flux density of the auxiliary pole stone is set so that the magnetic flux density after irreversible demagnetization of the auxiliary magnetic pole due to the maximum armature reaction during the rotating electrical machine operation becomes a predetermined value or more. Was set to an appropriate value. Thereby, even after the irreversible demagnetization of the secondary magnetic pole due to the maximum armature reaction during operation of the rotating electrical machine, the secondary magnetic pole is maintained at a magnetic flux density that is necessary or higher for the leakage magnetic flux suppression function between the main magnetic poles. The output of the rotating electrical machine can be stably maintained. In particular, as in claim 2 of the present invention, by setting the magnetic flux density of the sub magnetic pole to a value larger than the magnetic flux density of the main magnetic pole, a material cheaper than the sub magnetic pole can be used for the main magnetic pole. While suppressing an increase in cost of the rotating electrical machine, the leakage magnetic flux suppressing function between the main magnetic poles fulfilled by the sub-magnetic pole can be stably maintained.
[0008]
In the rotating electrical machine according to claim 3 of the present invention, the maximum armature reaction in the rotating electrical machine according to claim 1 or 2 is due to the restraint current at the time of starting the rotating electrical machine. In general, the maximum armature current of a rotating electrical machine is a binding current when starting the rotating electrical machine. As a result, it is possible to reliably prevent the function deterioration of the sub magnetic pole due to the maximum armature reaction during the operation of the rotating electric machine.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, an example in which the rotating electrical machine 1 according to the first embodiment of the present invention is applied to an engine starting motor will be described with reference to the drawings.
[0010]
FIG. 4 shows the configuration of the rotating electrical machine 1 according to the first embodiment of the present invention.
[0011]
The rotating electrical machine 1 is provided in a cylindrical yoke 2, and includes an armature 6 that is rotatably provided in the yoke 2, and a field magnetic pole 3 that is fixed inside the yoke 2.
[0012]
The armature 6 includes a shaft 7 rotatably supported in the yoke 2, a core 8 fixed to the shaft 7, an armature coil (not shown), a positive brush (not shown), and a negative brush (not shown). Z) is composed of a commutator (not shown) in sliding contact.
[0013]
The field magnetic pole 3 is arranged between a plurality of (six in the first embodiment) main magnetic poles 4a to 4f that generate magnetic flux acting on the magnetic flux generated by the armature coil, and between the main magnetic poles 4a to 4f. The plurality of (6 in the first embodiment) sub magnetic poles 5a to 5f that increase the effective magnetic flux of the main magnetic poles 4a to 4f.
[0014]
The main magnetic poles 4a to 4f are permanent magnets having a magnetic pole direction in a direction from the yoke 2 toward the armature 6, and as shown in FIG. 4, the armature 6 side polarity is spatially shifted by 60 °. N poles and S poles are arranged at equal intervals so as to be alternately positioned. That is, when the polarity of the main pole 4a on the armature 6 side is S, the polarity of the main poles 4c, 4e on the armature 6 side is S, and the polarity of the main poles 4b, 4d, 4f is N. .
[0015]
The sub magnetic poles 5a to 5f are arranged between two adjacent main magnetic poles (4a and 4b, 4b and 4c, 4c and 4d, 4d and 4e, 4e and 4f, 4f and 4a). A permanent magnet having a magnetic pole direction in the direction toward the surface and having the same polarity opposite to the polarity of the side surface of the adjacent main magnetic pole. That is, between the main magnetic pole 3a and the main magnetic pole 3b, when the sub magnetic pole 5a with the S pole facing the main magnetic pole 4a and the N pole facing the main magnetic pole 4b is disposed between the main magnetic pole 4a and the main magnetic pole 4b, The sub-magnetic pole 5b with N facing the main magnetic pole 4b and S facing the main magnetic pole 4c has the S pole facing the main magnetic pole 4c and the N pole facing the main magnetic pole 4d between the main magnetic pole 4c and the main magnetic pole 4d. The sub magnetic pole 5c is between the main magnetic pole 4d and the main magnetic pole 4e, the main magnetic pole 4d is facing N, the main magnetic pole 4e is facing S, and the sub magnetic pole 5d is between the main magnetic pole 4e and the main magnetic pole 4f. A sub-magnetic pole 5e with an S-pole facing toward the main pole 4f and an N-pole facing toward the main magnetic pole 4f is disposed between the main magnetic pole 4f and the main magnetic pole 4a. Has been.
[0016]
Next, changes in the magnetic characteristics of the sub magnetic poles 5a to 5f and selection of materials during operation of the rotating electrical machine 1 according to the first embodiment of the present invention will be described.
[0017]
FIG. 2 shows the BH characteristics of the sub magnetic poles 5 a to 5 f of the rotating electrical machine 1. The vertical axis represents the magnetic flux density B, and the horizontal axis represents the magnetic field strength H. The magnetic flux density Br when H = 0 is the residual magnetic flux density of the sub magnetic poles 5a to 5f alone. The operating point A of the sub magnetic poles 5a to 5f is an intersection of the BH characteristic and the permeance line P. The BH characteristic changes linearly from the operating point A to the left in FIG. 2, and its inclination changes at the bending point C, and the inclination from the bending point C to the left becomes steeper. Further, the BH characteristic shown in FIG. 2 is necessary and sufficient for maintaining the function of the sub magnetic poles 5a to 5f, that is, the function of suppressing the leakage magnetic flux of the main magnetic poles 4a to 4f.
[0018]
First, changes in the magnetic characteristics of the sub magnetic poles 5a to 5f during the operation of the rotating electrical machine 1 according to the first embodiment of the present invention will be described.
[0019]
If the armature reaction is not, the magnetic flux density at the operating point A of the auxiliary pole 5a~5f is B _0. Next, when the rotating electrical machine 1 is operated and the reverse magnetic field −H ₁ is applied due to the armature reaction, the permeance line P moves in parallel to the left in the figure, so that the operating points of the sub magnetic poles 5a to 5f are point D. . Further, when the reverse magnetic field −H ₁ due to the armature reaction disappears, the operating point of the sub magnetic poles 5 a to 5 f returns from the point D to the point A again on the BH characteristic. That is, no irreversible demagnetization occurs.
[0020]
When the reverse magnetic field −H ₂ due to the maximum armature reaction acts, the permeance line P moves in parallel to the left in the figure, and the operating points of the sub magnetic poles 5a to 5f pass through the bending point C to become point E. In this case, even if the reverse magnetic field −H ₂ disappears, the operating point of the sub magnetic poles 5a to 5f does not return to the point A, but on the line EA ′ parallel to the line segment CA to the right in the figure, the point A ′. Return to. Point A ′ is the intersection of permeance line P and line segment EA ′. The magnetic flux density at this time is B ₁ and is smaller than B ₀ . That is, irreversible demagnetization occurs in the sub magnetic poles 5a to 5f, and B ₀ -B ₁ becomes an irreversible demagnetization amount due to the reverse magnetic field -H ₂ due to the armature reaction. Since the BH characteristics of the sub magnetic poles 5a to 5f after the occurrence of irreversible demagnetization are curves A'ET, the function of the sub magnetic poles 5a to 5f, that is, the leakage magnetic flux suppressing function of the main magnetic poles 4a to 4f can be maintained. Can not.
[0021]
Next, selection of materials for the sub magnetic poles 5a to 5f will be described.
[0022]
FIG. 1 shows the BH characteristics of the sub magnetic poles 5a to 5f of the rotating electrical machine 1 when two different types of permanent magnet materials X and Y are used. The BH characteristic of the permanent magnet material Y is the same as the BH characteristic shown in FIG.
[0023]
As shown in FIG. 1, the bending point F in the BH characteristic of the permanent magnet material X is on the left side of the bending point C in the BH characteristic of the permanent magnet material Y, and the coercive force of the permanent magnet material X is It is larger than the coercive force of the permanent magnet material Y.
[0024]
When the reverse magnetic field −H ₂ acts due to the maximum armature reaction of the rotating electrical machine 1, the operating point of the sub magnetic poles 5 a to 5 f by the permanent magnet material X is a point G in FIG. This point G is the right side of the bending point F, i.e. since B-H characteristic is in the linear portion, the opposing magnetic field -H ₂ is eliminated, the operating point of the sub pole 5a~5f returns to point A. That is, no irreversible demagnetization occurs. Therefore, by adopting the permanent magnet material X having a larger coercive force as the material of the sub magnetic poles 5a to 5f, the irreversible demagnetization of the sub magnetic poles 5a to 5f is performed when the reverse magnetic field −H ₂ due to the maximum armature reaction acts. Can be prevented.
[0025]
Here, the maximum armature reaction will be briefly described. In general, the magnitude of the armature reaction in the rotating electrical machine 1 is proportional to the magnitude of the current flowing through the armature coil (not shown). In the case of an engine starter motor, the maximum current that flows through an armature coil (not shown) is the current when the key switch is turned on to energize the rotating electrical machine 1 and the armature is not rotating (so-called Bound current). By the way, the binding current increases as the capacity of the battery (not shown) increases and as the temperature decreases. Therefore, the maximum armature reaction in the rotating electrical machine 1 is maximized by the binding current when combined with the battery having the maximum capacity among the batteries that may be used under the minimum use temperature condition. The magnetic characteristics of the sub magnetic poles 5a to 5f may be calculated based on this value.
[0026]
In the rotary electric machine 1 according to the first embodiment of the present invention described above, the coercive force of the auxiliary magnetic poles 5a to 5f has a coercive force that does not cause irreversible demagnetization even when subjected to a reverse magnetic field due to the maximum armature reaction. By adopting a large permanent magnet material X, the irreversible demagnetization of the sub magnetic poles 5a to 5f is prevented, the leakage magnetic flux suppressing function of the main magnetic poles 4a to 4f of the sub magnetic poles 5a to 5f is maintained, and the output of the rotating electrical machine 1 The decrease could be prevented.
[0027]
On the other hand, the magnitude of the reverse magnetic field due to the maximum armature reaction acting on the main magnetic poles 4a to 4f is smaller than the magnitude of the reverse magnetic field due to the maximum armature reaction acting on the sub magnetic poles 5a to 5f, as shown in FIG. Therefore, even if an inexpensive material having a smaller coercive force than the permanent magnet material X used for the sub magnetic poles 5a to 5f is used for the main magnetic poles 4a to 4f, the main magnetic poles 4a to 4f receive a reverse magnetic field due to the maximum armature reaction. It is possible to prevent irreversible demagnetization. In this case, while suppressing an increase in cost, the irreversible demagnetization of the sub magnetic poles 5a to 5f is prevented, the leakage magnetic flux suppressing function of the main magnetic poles 4a to 4f of the sub magnetic poles 5a to 5f is maintained, and the output of the rotating electrical machine 1 is reduced. Can be prevented.
[0028]
(Second Embodiment)
In the rotating electrical machine 1 according to the second embodiment of the present invention, the material selection method for the sub magnetic poles 5a to 5f is different from that of the first embodiment. That is, in the first embodiment, the selection is made focusing on the coercive force of the permanent magnet material, but in the second embodiment, the selection is made focusing on the magnetic flux density.
[0029]
Below, selection of the material of sub magnetic pole 5a-5f is demonstrated.
[0030]
FIG. 3 shows the BH characteristics of the sub magnetic poles 5a to 5f of the rotating electrical machine 1 when two different types of permanent magnet materials W and Y are used. The BH characteristic of the permanent magnet material Y is the same as the BH characteristic shown in FIG.
[0031]
As shown in FIG. 3, the coercive force is the same for the permanent magnet material W and the permanent magnet material Y. However, regarding the magnetic flux density, the permanent magnet material W is larger than the permanent magnet material Y. If the armature reaction is not, the operating point of the sub pole 5a~5f is a point J, the magnetic flux density at this time is B _2. Further, the bending point K in the BH characteristic of the permanent magnet material W is on the right side of the drawing from the bending point C in the BH characteristic of the permanent magnet material Y.
[0032]
Here, when the reverse magnetic field −H ₂ acts due to the maximum armature reaction of the rotating electrical machine 1, the operating points of the sub magnetic poles 5 a to 5 f by the permanent magnet material W pass through the bending point K as shown in FIG. L. Therefore, even if the reverse magnetic field −H ₂ disappears, the operating point of the sub magnetic poles 5a to 5f does not return to the point J, but returns to the point M to the right in the drawing on the line LM parallel to the line KJ. Point M is an intersection of permeance line P and line segment LM. The magnetic flux density at this time is B ₃ and is smaller than B ₂ . That is, irreversible demagnetization occurs in the sub magnetic poles 5a to 5f, and B ₂ -B ₃ becomes an irreversible demagnetization amount due to the reverse magnetic field −H ₂ due to the maximum armature reaction. However, even after irreversible demagnetization occurs, the BH characteristics of the sub magnetic poles 5a to 5f become the curve MLT, which is a necessary and sufficient condition for maintaining the leakage magnetic flux suppressing function of the main magnetic poles 4a to 4f of the sub magnetic poles 5a to 5f. Since it exceeds a certain curve ACT, the sub magnetic poles 5a to 5f can maintain the leakage magnetic flux suppressing function of the main magnetic poles 4a to 4f. Thereafter, no matter how many times the reverse magnetic field -H2 due to the maximum armature reaction is received, the BH characteristics of the sub magnetic poles 5a to 5f are stabilized at the curve MLT.
[0033]
In the rotating electrical machine 1 according to the second embodiment of the present invention described above, the magnetic flux density is not less than a predetermined value even after irreversible demagnetization occurs due to the maximum armature reaction in the sub magnetic poles 5a to 5f. By adopting the permanent magnet material W having a high magnetic flux density, it is possible to maintain the leakage magnetic flux suppressing function of the main magnetic poles 4a to 4f of the sub magnetic poles 5a to 5f and prevent the output of the rotating electrical machine 1 from being lowered.
[0034]
On the other hand, the magnitude of the reverse magnetic field due to the maximum armature reaction acting on the main magnetic poles 4a to 4f is smaller than the magnitude of the reverse magnetic field due to the maximum armature reaction acting on the sub magnetic poles 5a to 5f, as shown in FIG. Therefore, even if an inexpensive material having a smaller magnetic flux density than the permanent magnet material W used for the sub magnetic poles 5a to 5f is used for the main magnetic poles 4a to 4f, the main magnetic poles 4a to 4f after occurrence of irreversible demagnetization due to the maximum armature reaction. The magnetic flux density can be a predetermined value or more. In this case, while suppressing an increase in cost, the leakage magnetic flux suppressing function of the main magnetic poles 4a to 4f of the sub magnetic poles 5a to 5f can be maintained, and a decrease in the output of the rotating electrical machine 1 can be prevented.
[0035]
Further, in the rotating electrical machine 1 according to the first embodiment or the second embodiment of the present invention, as shown in FIG. 5, the soft magnetic bodies 9a to 9f are interposed between the main magnetic poles 4a to 4f and the sub magnetic poles 5a to 5f. (For example, soft iron) may be inserted.
[Brief description of the drawings]
FIG. 1 shows respective BH characteristics when two different kinds of permanent magnet materials X and Y are used in the sub magnetic poles 5a to 5f of the rotating electrical machine 1 according to the first embodiment of the present invention.
FIG. 2 is a diagram showing BH characteristics of sub magnetic poles 5a to 5f of the rotating electrical machine 1 according to the first embodiment of the present invention.
FIG. 3 shows respective BH characteristics when two different types of permanent magnet materials W and Y are used in the sub magnetic poles 5a to 5f of the rotating electrical machine 1 according to the second embodiment of the present invention.
FIG. 4 is a schematic radial sectional view of the rotating electrical machine 1 according to the first embodiment of the present invention.
FIG. 5 is a schematic radial cross-sectional view of a modified example of the rotating electrical machine 1 according to the first embodiment or a modified example of the second embodiment.
FIG. 6 is a development view of a field and an armature in a general permanent magnet field type rotating electric machine, and an explanatory diagram showing a magnetic flux distribution due to an armature reaction corresponding thereto.
[Explanation of symbols]
1 rotary electric machine 2 yoke 3 field magnetic pole 4a~4f main magnetic 5a~5f auxiliary magnetic pole 6 armature 7 shaft 8 cores 9a~9f soft magnetic A operating point A 'operating point B the magnetic flux density B ₀ .about.B ₃ flux density Br Residual magnetic flux density C Bending point D Operating point E Operating point F Bending point G Operating point H Magnetic field strength, magnetic flux J Operating point K Bending point L Operating point M Operating point P Permeance wire W Permanent magnet X Permanent magnet Y Permanent magnet

Claims (3)

A plurality of main magnetic poles formed of permanent magnets alternately arranged with a certain interval in the circumferential direction on the inner circumferential surface of the yoke and each magnetic pole surface facing the armature;
A rotating electric machine comprising: a sub-magnetic pole made of a permanent magnet having a pair of magnetic pole faces having the same polarity as the polarity of the magnetic pole face on the armature side of the adjacent main pole arranged between the main magnetic poles; In
The residual magnetic flux density of the auxiliary magnetic pole is set to a value such that the residual magnetic flux density after occurrence of irreversible demagnetization of the auxiliary magnetic pole due to the maximum armature reaction during operation of the rotating electric machine becomes a predetermined value or more. Rotating electric machine. The rotating electrical machine according to claim 1 , wherein the residual magnetic flux density of the sub magnetic pole is set to a value larger than the magnetic flux density of the main magnetic pole. 3. The rotating electrical machine according to claim 1, wherein the maximum armature reaction is caused by a restraining current when starting the rotating electrical machine.

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