JP2938267B2 - DC machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC machine using a permanent magnet, and more particularly to a DC machine in which the magnetic flux distribution of the permanent magnet is improved.

[0002]

2. Description of the Related Art A general DC machine, such as a DC motor,
A permanent magnet for the field is provided on the stator side, and the rotor is rotated by energizing the armature conductor placed in the magnetic flux generated by the field magnet.

At this time, the attraction force acting between the field magnet of the DC motor and the core of the rotor rapidly changes depending on the rotation angle, so that cogging torque is generated. For example, considering the case where the rotor is between two arc-shaped field magnets, if the core of the rotor is located at a position facing one of the field magnets, a large torque acts on the core. I do. On the other hand, if the core is between the two field magnets,
The acting torque decreases sharply.

[0004] The cogging torque causes vibration and noise during operation of the DC motor. for that reason,
In order to reduce the vibration due to the cogging torque, the following measures are taken.

A so-called eccentric magnet is used which realizes a smooth change in magnetic flux density by reducing the magnetic flux density by thinning the end of the magnet.

A so-called skew magnet, which gradually shifts the magnetic flux density distribution in the rotational direction from the axial direction of the rotor, is used.

According to the above-mentioned method, since the change in the magnetic flux density distribution becomes smooth, it is possible to prevent a sudden change in the torque.

The radial anisotropic cylindrical magnet is magnetized by using a magnetizing device disclosed in Japanese Patent Application Laid-Open No. 63-260118. According to this method, a smooth sinusoidal magnetic flux distribution can be obtained.

[0009]

However, in the above-mentioned methods, there is a problem that a reduction in the maximum torque and the output is unavoidable because an effective magnetic flux is sacrificed for the rotational force. . Also, in the method of
There has been a problem that demagnetization occurs due to armature reaction because the end of the magnet is made thin.

In addition, in the method (1), there is a problem that the magnetization control is difficult and the torque is reduced in a portion where the magnetization is insufficient, so that the maximum torque is inevitably reduced, and the output is reduced. . In addition, demagnetization could not be avoided due to insufficient magnetization.

In addition, it is conceivable to take measures against vibration and noise by using a floating structure using a vibration-proof rubber or the like for the bracket portion of the motor. However, in this case, the cost increases due to the addition of parts, which is effective. Could not be said to be a countermeasure.

The present invention has been made in view of the above points, and can reduce the cogging torque without lowering the production cost, reducing the output and causing no demagnetization, and reducing vibration and noise. It is intended to provide a DC machine.

[0013]

In order to solve the above-mentioned problems, the present invention provides a stator including P pairs of permanent magnets for generating a field magnetic flux, a slot angle of θ ₁ , and an angle between teeth. And a rotor having θ ₂ , wherein n is an integer equal to or greater than 0, and the angle θ a _{2 (n + 1)} is calculated by the following equations (1) and (2) with reference to the center of the magnetic pole of the permanent magnet. , Θa
When _{the (2n + 1)} have _{defined, θa 2 (n + 1)} = (2n + 1) θ 1/2 + θ 2 ..................... (1) where, 0 ° ≦ (2n + 1 ) θ _{1/2 + θ 2 ≦ π} / 2P θa (2n + 1) = nθ 1 + θ 2/2 ........................... (2) _{where, 0 ° ≦ nθ 1 + θ} 2/2 ≦ π / 2P said permanent The magnet has the inflection point positions of the rising and falling regions of the magnetic flux density distribution at both ends thereof, the angle θa _{2 (n + 1)} or θa
_{(2n + 1)} is set near one of the angles.

[0014]

[Function] When the rotor of the DC machine rotates, the phenomenon of the rotor slot passing through the stator-side permanent magnet was analyzed. When the slot penetrated the permanent magnet and passed the inflection point, the rotor Cogging torque was generated in the direction that hindered rotation, and cogging torque was generated in the direction to rotate the rotor when the slot was separated from the permanent magnet and passed the inflection point.

In the conventional DC machine, no consideration is given between the slot position of the rotor and the position of the inflection point of the permanent magnet on the stator side. Therefore, the direction is such that the rotation of the rotor is hindered and the rotation is accelerated. It was unavoidable that the cogging torques appeared alternately and greatly.

On the other hand, in the present invention, the inflection point position of the rising / falling region of the field magnetic flux density distribution of the permanent magnet is set near the above-mentioned angle from the relationship with the rotor slot and teeth position. As a result, the cogging torque in the direction of accelerating the rotation of the rotor and the cogging torque in the direction of deceleration appear almost simultaneously, and the two torques substantially cancel each other, so that the cogging torque generated in the motor is largely reduced as a whole. be able to.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a preferred embodiment of the DC motor according to the present invention. The DC motor of the embodiment is
It includes a stator 10 and a rotor 110.

The stator 10 is formed by mounting a cylindrical permanent magnet 14 on the inner periphery of a yoke 12. As the permanent magnet 14, an anisotropic magnet such as a ferrite magnet or a neodymium magnet is used, and the right half thereof is formed as an S pole 16 and the left half thereof is formed as an N pole 18 around the Y axis. Here, the X axis orthogonal to the Y axis is designed to pass through the magnetic pole centers of the S pole 16 and the N pole 18, respectively.

The rotor 110 is rotatably supported inside the stator 10. Here, in order to facilitate understanding of the present invention, only the iron core constituting the rotor 110 is shown, and armature windings, commutators, brushes, etc., which are not directly related to the main part of the present invention, are excluded from the drawing. doing.

FIG. 2 shows the magnetic flux density distribution of this DC motor, wherein the horizontal axis represents the rotation angle θ of the rotor 110, and the vertical axis represents the gap magnetic flux density between the permanent magnet 14 and the rotor 110. I have.

According to the study of the present inventor, it has been confirmed that the cogging torque acts in the opposite direction when the rotor 114 rotates, when the slot 114 enters the permanent magnet and when the slot 114 escapes. For example, consider the case where the slot 116 of the rotor 110 enters the N pole 18 and the case where it exits. At this time, while the slot 114 rushes and passes through the inflection point 100 at the rising portion of the magnetic flux density distribution of the N pole 18, a cogging torque acting in a direction opposite to the rotation direction is generated, and the slot 114 While escaping and passing the inflection point 100 at the falling portion of the magnetic flux density distribution, cogging torque acting in the same direction as the rotation of the rotor 110 is generated.

The same applies to the case where the slot 114 passes through the south pole 16.

FIG. 3 shows the concept of cogging torque A generated when the slot 114 of the rotor 110 passes through the inflection point 100 located on the inlet side of the N pole 18 when the rotor 110 is rotated counterclockwise. Is shown.

[0025] As shown in FIG.
When the rear end of 1 is near the inflection point on the inlet side of the N pole 18, a difference in magnetic flux density occurs in the rotor teeth 112, and this causes the cogging torque A in the direction indicated by the arrow A (the direction opposite to the rotation direction). generate. At this time, the larger the density difference of the magnetic flux in the teeth 112, the larger the cogging torque is generated.

When the rotor 110 further rotates and the rear end of the slot 114 is located near the end of the N pole 18 on the entrance side, the region of the N pole 18 facing the slot 114 (shown by oblique lines in FIG. The region shown in the figure) becomes a weak magnet because the magnetic material (the teeth 112) does not exist in the facing region. Therefore, the upstream teeth 112-1 close to the slots 114 become extremely strong magnets, and the magnetic imbalance is maximized. Therefore, the value of the cogging torque A generated at this time also becomes the maximum value.

Further, when the rotor 110 rotates and becomes as shown in FIG.
The flow of the magnetic flux also occurs, the difference in the density of the magnetic flux is reduced as a whole, and the value of the cogging torque A gradually decreases.

A similar phenomenon occurs on the exit side of the N pole 18. In this case, the generated cogging torque is
Contrary to the above, the direction is the same as the rotor rotation direction.

Therefore, like a conventional DC motor,
For example, the inflection points 100 at both ends of the N pole 18 are
Irrespective of the positions of the slots 114, 114, as shown by the characteristic curve 200 in FIG. 4, the rotation in the forward direction (the same direction as the rotation direction) and the reverse direction (the direction opposite to the rotation direction) occur as the rotor 110 rotates. The maximum cogging torque appears alternately at different timings.

On the other hand, in the present invention, the teeth 112
Is θ ₂ and the interval between the slots 114 is θ ₁ , for example, the inflection point position 100 on the entrance side of the N pole 18 is set to a ₁ , a ₂ , a _{3 in} relation to θ ₁ and θ _2. , A ₄ , a
₅ and a ₆ , and the inflection points at the exit side position 100 of the N pole 18 are set to a ′ ₁ , a ′ ₂ , a ′ ₃ , a
_{'4, a'5,} by setting at any position _a'6, is characterized in reducing the cogging torque.

That is, n is an integer of 0 or more, 2D is the inner diameter of the permanent magnet 14, S pole 16 and N pole 18 are P pairs (however, P = 1 in the embodiment).

At this time, when the inflection point 100 is set to an even-numbered position a _{2 (n + 1)} , its angular position θa _{2 (n + 1) with} respect to the X axis is given by the following equation. .

(Equation 1) The coordinates of each inflection point a _{2 (n + 1)} are given by the following equations.

(Equation 2) When the inflection point is set at the odd-numbered position a _{2 (n + 1)} , the value of the angular position θa _{(2n + 1) with} respect to the X axis is given by the following equation.

(Equation 3) The coordinates of the inflection point a _{2n + 1} are given by the following equation.

(Equation 4) At this time, it should be noted that the position of the inflection point on the entrance side of the N pole 18 is determined by the even-numbered positions a ₂ ,
If the position is set to any one of the positions a ₄ and a ₆ , the inflection point position on the exit side of the N pole 18 is also an even-numbered position a ′ ₂ , a ′ ₄ , a ′ ₆ represented by the above equation (1). Must be set to one of the positions. When the inflection point position on the entrance side of the N pole 18 is set to any of odd-numbered positions of a ₁ , a ₃ , and a ₅ , the inflection point on the exit side is also a ′ ₁ , a ′ ₃ , A
It must be set to one of the positions of ' ₅ .

Therefore, the inflection points at both ends of the N pole 18 are a ₆ ,
When set to the position of the _a'6, the angle ± theta at that time
a ₆ is given by Equation 1 above. That is, in Equation 1, n
= 2, and the angle may be obtained. Then, based on the X-axis, + angle .theta.a ₆ becomes the position of the inlet-side inflection point a _6, the angle of -Shitaei ₆ is a position of the outlet-side inflection point θa' _6.

Further, when setting the opposite ends inflection point of N pole 18 in odd-numbered, for example a _5, when setting the _a'5 substitutes a ₂ = 2 in the equation 3, the angle + .theta.a _5, −θ
a a ₅ may be obtained.

It should be noted that when the inflection point on the entrance side of the N pole 18 is set to the even-numbered value of the above equation 1, the inflection point position on the exit side is also set to the even-numbered inflection point position. It must be. Incidentally, it sets one of the inflection point of the N pole to a _6, it is possible to set the other inflection reduced to the position of the _a'4.

The same applies to the case where odd-numbered inflection points are set at both ends of the N pole 18.

FIGS. 5A to 5E and FIGS. 6F and 6G.
Describes the operation of the conventional DC motor and the operation of the DC motor of the present embodiment in comparison. The left column in the drawing shows the operation of the conventional DC motor, and the right column shows the operation of the DC motor of the present embodiment.

Here, the DC motor of the embodiment has an N pole 1
8, the inflection point positions at both ends of the S-pole 16, the equation 3 a ₅ represented by the set angular position of the _a'5, the external magnet from these inflection point is used after removal by cutting .

In the embodiments shown in FIGS. 5 and 6, the state in which the rotor 110 is rotated counterclockwise by 3 degrees to 18 degrees is schematically shown.

As shown in the left column of FIGS. 5 and 6, the inflection points at both ends of the S pole 16 and the N pole 18 are changed to the rotor 1 as in the prior art.
If it is set independently of the position of the slot 114, as the rotor 110 rotates sequentially, for example,
As shown in FIG. 5E, when the rotor 110 approaches the position of the inflection point on the inlet side of the S pole 16 and the N pole 18, a large cogging torque is generated in a direction that hinders the rotation of the rotor, and the rotation further proceeds. As shown in FIG.
6. When the slots 114, 114 approach the outlet side of the N pole 18, a cogging torque is generated in the direction of accelerating the rotor, contrary to the above.

That is, the maximum value of the magnetic unbalance that generates the cogging torque in the direction that hinders the rotation of the rotor and the maximum value of the magnetic unbalance that generates the cogging torque in the direction of accelerating the rotor are generated at different timings. In this conventional DC motor, as shown by a characteristic curve 200 in FIG. 4, cogging torque having a large peak is generated alternately and in the opposite direction.

On the other hand, as shown in the right columns of FIGS. 5 and 6, in the DC motor of the embodiment, when the rotor 110 sequentially rotates in the counterclockwise direction, at the timing shown in FIG. As shown in FIG. 3B, the point where the magnetic imbalance is maximum (the point where the cogging torque is maximum) is the S pole 1
6 at the both ends of the inlet and outlet sides of the N pole 6 and the both ends of the N pole 18 at the inlet and outlet sides.
Therefore, the cogging torque acting in the direction of accelerating the rotor 110 and the cogging torque acting in the direction of decelerating the rotor cancel each other, and the value of the cogging torque is greatly reduced as a whole. In FIG. 4, a characteristic curve 300 represents the characteristic of the cogging torque generated in the DC motor of the embodiment.

As is apparent from the drawing, it is understood that the cogging torque generated in the DC motor of this embodiment can be significantly reduced as compared with the conventional DC motor. FIG.
5 shows actual measurement data of cogging torque generated in each of the conventional DC motor shown in the left column in FIG. 5 and FIG. 6 and the DC motor of the present embodiment shown in the right column. According to this embodiment, the cogging torque is 5 times less than that of the conventional product.
It was confirmed that it could be reduced to one-half.

As described above, according to the DC motor of this embodiment, the cogging torque can be effectively suppressed without substantially affecting the effective magnetic flux directly contributing to the motor output.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention.

For example, in the above embodiment, the case where a pair of N pole and S pole is provided has been described as an example. However, the present invention is not limited to this, and two or more pairs of N pole and S pole may be used as necessary. It can also be provided.

In this case, the inflection point may be set in the same manner as in the above embodiment, with the center of each magnetic pole as a reference.

Further, in the above-described embodiment, the description has been made by taking an anisotropic magnet as an example. However, the present invention is not limited to this, and an isotropic magnet can be used if necessary.

Further, in the embodiment shown in FIGS. 5 and 6, S
Although the case where both ends of the pole and the N pole coincide with the inflection point positions on the entrance side and the exit side has been described as an example, the present invention is not limited to this. The width formed between the inflection points is larger than the width between the inflection points.
As shown in FIG. 8A, a parallel orientation may be used.
As shown in (B), a structure in which the outer region of the inflection point is thinned and partially eccentric may be employed.

Further, in the above embodiment, the case where the present invention is applied to a DC motor has been described as an example. However, the present invention is not limited to this, and may be applied to various DC generators and the like. it can.

[0051]

As described above, according to the present invention,
By setting the position of the inflection point in the rising / falling region of the field magnetic flux density distribution at both ends of the stator-side permanent magnet at an optimum position in relation to the angle of one slot of the rotor and the angle between the teeth, the present invention is applied to When applied to a motor, the cogging torque can be significantly reduced without lowering the output of the motor, etc., and when the present invention is applied to a DC generator, without adversely affecting the power generation output. And vibration can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining a setting position of an inflection point in a DC motor to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a relationship between a rotation angle of the DC motor shown in FIG. 1 and a gap magnetic flux density.

FIG. 3 is a schematic explanatory diagram of a principle of generating a cogging torque in a DC motor.

FIG. 4 is an explanatory diagram of correlation data between a rotor rotation angle and cogging torque measured using a conventional DC motor and the DC motor of the present embodiment.

FIGS. 5A to 5E are explanatory diagrams showing a change in the relative position between the rotor and the stator in a state where the rotor is driven to rotate counterclockwise three times at a time, and FIG. Represents a series of operations of the conventional DC motor, and the right column represents a series of operations of the DC motor of the present embodiment.

6 (a) and 6 (g) show changes in the relative position between the rotor and the stator when the rotor is driven to rotate counterclockwise three times at a time following FIG. 5; The operation of the conventional DC motor, and the right column shows the operation of the DC motor of this embodiment.

FIG. 7 is an explanatory diagram of actually measured cogging torque data of the conventional DC motor and the DC motor of the present embodiment.

FIG. 8A is an explanatory diagram in a case where a parallel orientation is applied to an outer region of an inflection point, and FIG. 8B is an embodiment in a case where the outer region of the inflection point is partially decentered. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stator 12 Yota 14 Permanent magnet 16 S pole 18 N pole 100 Inflection point 110 Rotor 112 Teeth 114 Slot

Claims (1)

(57) [Claims] 1. A DC machine comprising: a stator including P pairs of permanent magnets for generating a field magnetic flux; and a rotor having a slot angle of θ ₁ and an inter-teeth angle of θ ₂ , wherein n is 0 or more. And the angle θa _{2 (n + 1)} in the following equations (1) and (2) with respect to the center of the magnetic pole of the permanent magnet.
.theta.a if you define the _{(2n + 1), θa 2} (n + 1) = (2n + 1) θ 1/2 + θ 2 ..................... (1) where, 0 ° ≦ (2n + 1 ) _{θ 1/2 + θ 2 ≦} π / 2P θa (2n + 1) = nθ 1 + θ 2/2 ........................... (2) _{where, 0 ° ≦ nθ 1 + θ} 2/2 ≦ π / 2P said In the permanent magnet, the inflection point position of the rising and falling regions of the magnetic flux density distribution at both ends is the angle θa _{2 (n + 1)} or θa
A DC machine characterized by being set near one of the angles _{(2n + 1)} .