JPH1146471A - Magnet excited brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the peelings of the field magnets of a magnet type brushless motor while using the motor in a high torque at a good conversion efficiency until it rotates several times as fast as its usual rotation, by opposing its first and second rotors to its stator magnet pole, and by varying the relative phase of the synthetic magnetic pole of its first and second rotors to the magnetic pole of its first rotor correspondingly to the revolutions of its rotor. SOLUTION: Both first and second rotors 2a, 2b are disposed oppositely to a stator magnetic pole 11 with a narrow air gap 6 in between to form a brushless motor 50. Then, by the mechanism for making variable the relative phase of the synthetic magnetic pole of the first and second rotors 2a, 2b to the magnetic pole of the first rotor 2a correspondingly to the revolutions of a rotor 2, the same-polarlity magnets of the first and the second rotors 2a, 2b are aligned with each other when the revolutions of the rotor 2 is low, and are slipped at both the same-polarlity magnets from each other when the revolutions of the rotor 2 is high. Further, the interlinked magnetic flux quantity of both the rotors 2a, 2b is reduced responding to the relative magnetic pole slippage between both in the case of the high resolutions, and the same-polarity magnetic pole of the first and the second rotors 2a, 2b is aligned with each other around a rotational shaft 21 to make maximum the interlinked magnetic flux quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet type brushless motor useful as a motor using a permanent magnet as a field (for example, for a power source of an electric vehicle).

[0002]

2. Description of the Related Art In an internal combustion engine of an automobile or the like, a rotation region for generating a high torque is very narrow. Therefore, as shown in FIG. 10, a transmission composed of several types of gears having different gear ratios is used so that the vehicle can run at an arbitrary speed from a low speed to a high speed.

However, as shown in FIG. 11, the relationship between the rotational speed and the torque of a conventional Briless DC motor using permanent magnets is such that the torque decreases linearly as the rotational speed increases in inverse proportion to the rotational speed. . The voltage applied to the motor is V,
Assuming that the total magnetic flux obtained by multiplying the strength of the magnetic field created by the field of the motor by the effective area of the field is Φ, the number of windings of the armature is Z, and the resistance is R, the maximum value of the rotational speed (n _max ) is V / ΦZ, the maximum value of the torque (T _max ) is ΦZV / R. When the voltage V is doubled, the maximum torque and the maximum rotation speed are both doubled.
By changing the number of windings Z, the maximum torque and the maximum rotation speed can be changed. The torque increases as the total magnetic flux Φ increases, but it is necessary to determine the upper limit value while paying attention to magnetic saturation on the armature side.

However, in the conventional brushless DC motor, a high torque can be obtained in a low-speed rotation range, but it is difficult to rotate at a high speed because the variable range of the rotation speed is narrow.
The maximum value of the rotation speed (n _max ) is reduced by reducing the total magnetic flux Φ at the time of high-speed rotation by a technique called “field weakening”.
May be raised. When the rotational speed is low, a torque as shown by a solid line in FIG. 11 is obtained with a large total magnetic flux Φ, and when the rotational speed is high, the total magnetic flux Φ is reduced to obtain a characteristic as shown by a broken line in FIG. Thus, it is conceivable to rotate to a higher rotation speed.

It has also been proposed to change the total magnetic flux with the number of revolutions in the case of a generator. JP-A-7-2362
No. 59 "Permanent Magnet Generator" includes a permanent magnet generator which generates an electromotive force in the stator by interlinkage magnetic fluxes from a plurality of poles of the field permanent magnet used in the rotor. A permanent magnet for magnetic flux bypass having the same number of poles as the field permanent magnet and rotatably disposed coaxially on its side in proximity to the permanent magnet, and a governor mechanism displaced according to the rotation speed of the rotor; The permanent magnet for magnetic flux bypass can be rotated by a half cycle of the magnetic polarity in response to the displacement of the governor mechanism, and when the rotor is stopped, the magnetic polarity of the permanent magnet for bypass is changed to the magnetic field for the field. There is disclosed an arrangement in which the permanent magnets are arranged to have the same polarity as the permanent magnets, and the governor mechanism rotates the bypass permanent magnets to a position having a polarity opposite to that of the field permanent magnets in a high-speed region. In this way, at low speed rotation, the linkage flux from the magnetic pole of the field permanent magnet is increased,
During high-speed rotation, the linkage magnetic flux from the field permanent magnet is weakened to keep the generated power constant.

[0006]

However, the field weakening control method always monitors the torque, the rotational speed, and sometimes the rotational acceleration, and performs a complicated calculation based on those numerical values to determine the magnitude and phase of the current. Must be controlled, requiring complex and expensive control circuits, including high-speed computers. Also, in the conventional magnet type brushless DC motor, it has been found that even if an attempt is made to reduce the amount of interlinkage magnetic flux by shorting the magnetic poles on the side of the field permanent magnet as in the above-described conventional generator, it cannot be sufficiently reduced. did. That is, as is apparent from the equation of the maximum value of the rotation speed n _max = V / ΦZ, the means for increasing n _max (also called the no-load rotation speed) by a factor of two or more is based on a simple decrease in the total magnetic flux Φ. Need to be reduced by 50% or more, but the present inventors have confirmed that short-circuiting the side surfaces of the field magnet only reduces at most less than about 20 to 30%. Further, in the above-described conventional generator, since the permanent magnet for magnetic flux bypass is outside the closed magnetic circuit formed by the rotor and the stator of the generator, if it hardly contributes to the output of the generator, When there is a conductive and / or magnetic structure such as a motor case near the permanent magnet for magnetic flux bypass, an eddy current is generated inside the motor case by the magnetic flux generated by the permanent magnet for bypass. It is conceivable that the conversion efficiency of the electric motor is reduced due to the attraction force with the magnetic material. Further, since the permanent magnet for bypass is an additional component, there is a drawback that the generator is easily increased in size.

Further, with the recent demand for high-speed rotation of the rotor, the position of the conventional field magnet, for example, the field magnet in the conventional surface magnet type rotor 500 shown in the sectional view of the main part of FIG. A large centrifugal force acts on the 503 during high-speed rotation,
There was a risk of peeling from the rotor core 507.

Therefore, according to the present invention, a high torque can be obtained as in the conventional case at a low rotation speed, and the conversion can be used with a high torque up to a rotation speed nearly three times higher than that of the conventional one with high conversion efficiency. It is another object of the present invention to provide a magnet type brushless electric motor (for example, for driving an automobile) in which the field magnet is prevented from peeling in a high rotation speed range.

[0009]

According to the present invention, there is provided a stator having a plurality of stator poles and a winding for generating a rotating magnetic field in the stator poles, a rotating shaft and a rotating shaft. A rotor having a field magnet that is provided and rotates with respect to the plurality of stator magnetic poles; and detects a position of the rotor with respect to the stator and supplies a current to the winding according to the detected position. In the magnet type brushless electric motor having a control circuit for performing the operation, the rotor is arranged around a rotation axis, and a first field magnet in which magnetic poles having different polarities are sequentially arranged in the rotation direction and the first field magnet. A first rotor having a cylindrical cover disposed on the peripheral surface of the
A second field magnet, which is rotatable relative to the rotor and is arranged around the rotation axis and in which magnetic poles of different polarities are lined up sequentially in the rotation direction, and a peripheral surface of the second field magnet. A second rotor having a cylindrical cover disposed thereon, wherein the first and second rotors are opposed to the stator magnetic poles, and the first and second rotors are A magnet type brushless motor characterized by having a mechanism for changing the phase of a synthesized magnetic pole with respect to the magnetic pole of a first rotor as the rotor rotates.

Further, the present invention provides a stator having a plurality of stator magnetic poles and a winding for generating a rotating magnetic field on the stator magnetic pole, a rotating shaft and a plurality of stators provided on the rotating shaft. A rotor having a field magnet that rotates with respect to a magnetic pole, and a control circuit that detects a position of the magnetic pole of the rotor with respect to the stator and supplies a current to the winding according to the position. In the brushless electric motor, the rotor includes a first rotor core disposed around a rotation axis, a field magnet embedded in the first rotor core, and magnetic poles having sequentially different polarities in the rotation direction of the first rotor core. Are arranged side by side, and a field magnet is buried in a second rotor core arranged around the rotation axis, and the magnets have different polarities sequentially in the rotation direction of the second rotor core. The magnetic poles are aligned and the first rotor A second rotor that is rotatable with respect to the rotor, wherein the first and second rotors are opposed to the stator magnetic poles, and a combined magnetic pole of the first and second rotors; Characterized in that it has a mechanism for changing the phase of the rotor with respect to the magnetic pole of the first rotor as the rotor rotates.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. FIG. 1 is a perspective view of an exploded main part of a magnet type brushless DC motor provided with an internal magnet type rotor according to one embodiment of the present invention. In FIG. 1A, a field winding 12 for generating a rotating magnetic field around a plurality of (12 poles in this figure) stator magnetic poles 11 is wound around the stator 1. The rotor 2 has a rotating shaft 21 for indicating the magnetic pole positions of the field magnets 31 and 32.
And a sensor pole 22 (for example, a ferrite plastic magnet) having a magnetic pole pattern formed in the rotation direction of the outer peripheral surface and having the same central angle as the first and second field magnets 31 and 32. Etc.). The rotor 2 has a first internal magnet type rotor 2a and a second internal magnet type rotor 2b capable of rotating relative to the first rotor 2a.
It consists of The first and second rotors 2a and 2b are respectively embedded in the through holes of the number of magnetic poles along the rotation shaft 21 provided in the ferromagnetic rotor cores 7 and 8 (for example, made of SS400). Field magnet 31, second field magnet 3
2 (for example, Nd-Fe-B based anisotropic sintered magnet manufactured by Hitachi Metals: HS37BH, etc.). For this reason,
A total of eight magnetic poles N and S are formed alternately at equal intervals in the outer peripheral surface rotation direction of the rotor cores 7 and 8. Then, the position of the arbitrary magnetic pole of the field magnetic pole 4 with respect to the stator 1 is determined by the sensor magnet 2.
2, a control circuit (not shown) for switching the current supplied to the field winding 12 in accordance with the position of the magnetic pole is provided to generate a predetermined rotating magnetic field in the stator magnetic pole 11. ing. As shown, the first and second rotors 2
Both a and b are arranged opposite to the stator magnetic pole 11 with a narrow air gap 6 therebetween, and constitute a magnet type brushless motor 50 of the present invention. With this configuration, the magnetic fluxes emitted from the first and second rotors 2a and 2b are both the stator magnetic poles 1
1 and is linked to the field winding 12 efficiently,
Leakage magnetic flux passing through the surrounding structures is suppressed to be small, and the problem of generating a loss such as eddy current loss in the surrounding structures can be avoided.

FIGS. 1B and 2B show that the second rotor 2b is rotated in the direction of rotation of the rotor 2 relative to the first rotor 2a, so that the magnetic pole positions of the two rotors can be changed. Is shown. The phase of the magnetic pole obtained by combining the first and second rotors 2a and 2b with respect to the magnetic pole of the first rotor 2a changes as the rotor 2 rotates. The energization of the field winding 12 is controlled by detecting the magnetic pole of the sensor magnet 22 by detecting means (not shown) such as a Hall element. In the case of a brushless DC motor, the maximum torque can be obtained theoretically by making the center of the energization period of the rotating magnetic field generating winding coincide with the NS switching point of the field magnetic pole. However, in anticipation of a delay in the rise of the current with respect to the energization command signal due to the inductance of the winding for generating the rotating magnetic field, it is widely practiced to move the center of the energization period forward in the rotation direction from the NS switching point of the field magnetic pole. The angle at which the energization period is advanced is generally called an advance angle. In the present invention, setting of this advance angle is also important.

FIGS. 2A and 2B show the sensor magnet 2.
2 shows the positional relationship between the second magnetic pole and the magnetic poles of the first rotor 2a and the second rotor 2b. In FIG. 1A and FIG. 2A, the first rotor 2a and the second rotor 2b have the same magnetic poles adjacent to each other, so that the first and second rotors 2a and 2b are combined. (For example, the center of the composite magnetic pole) is in the same phase as the magnetic poles of the sensor magnet 22 and the first rotor 2a (for example, the center of the magnetic pole), but FIG. 1B and FIG. (B) shows a state in which the second rotor 2b is shifted in the forward rotation direction with respect to the first rotor 2a. Here, the first rotor 2a and the second rotor 2b generate exactly the same amount of magnetic flux, and the second rotor 2b
, The phase of the combined magnetic poles of the first and second rotors 2a and 2b is the same as that of the first and second rotors 2a and 2b. The average value of the magnetic pole phases is obtained, and the combined phase of the magnetic poles (for example, the center of the combined magnetic pole) is in the rotation forward direction with respect to the phase of the magnetic pole of the first rotor 2a (for example, the center of the magnetic pole). Lead angle:
(A / 2 degrees).

When the rotation speed of the rotor 2 is low, a mechanism for changing the phase of the combined magnetic pole of the first and second rotors with respect to the magnetic pole of the first rotor 2a with the rotation of the rotor 2 is used. As shown in FIGS. 1A and 2A, the same magnetic poles of the first and second rotors 2a and 2b are arranged side by side. It is desirable that the state be as shown in FIG. That is,
When the magnetic poles deviate, any S pole of the first rotor 2a, any N pole of the second rotor 2b, any N pole of the first rotor 2a, and the second rotor 2b Of the rotating shaft 21 partially overlaps when viewed from the longitudinal direction of the rotating shaft 21. As described above, a local short circuit of the generated magnetic flux occurs in a portion where the opposite magnetic poles are adjacent to each other, so that the amount of interlinkage magnetic flux reaching the field winding 12 on the stator 1 side is reduced. . That is, when the rotation speed is high, the amount of interlinkage magnetic flux is reduced according to the relative magnetic pole deviation between the two, and when the rotation speed is low, the first and second rotors 2a,
Since the magnetic poles 2b are arranged around the rotation axis 21, the amount of interlinkage magnetic flux is maximized. Since the magnet type brushless motor 50 of the present invention has the above-described configuration, it is possible to control the amount of interlinkage magnetic flux according to a wide range of rotation speed change, and the rotor 2 is rotated at high speed. Even the first,
Since the second field magnets 31 and 32 are fixed inside the first and second rotor cores 7 and 8, respectively, the high speed which is a problem in the conventional surface magnet type rotor 500 of FIG. Separation of the field magnet during rotation does not occur.

Although the internal magnet type rotors 2a and 2b have the field magnets in the shape of arc segments, it is needless to say that field magnets of other shapes may be embedded. FIG. 4 shows a hole 321 through which a rotating shaft (not shown) is inserted at the center of a thin ferromagnetic disk (for example, made of silicon steel) 308 having a thickness of 0.45 mm and the block-shaped field magnets 3 of the number of magnetic poles are rotated. Hole 34 for embedding along an axis (not shown)
9 may be passed through a rotating shaft (not shown) and the field magnets 3 may be arranged and stacked to form the internal magnet type rotor 100 shown in FIG.

FIG. 5A shows another embodiment of the internal magnet type rotor in which the magnetization direction of the field magnet 111 is at an angle (0 <0) with respect to the radial direction of the rotor core 112.
θ ′ <90 degrees). In this arrangement, the number of field magnets 111 is two per magnetic pole formed on the outer peripheral side of the rotor core 112, and two field magnets forming one magnetic pole are arranged such that magnetic poles of the same polarity face each other. Have been. This configuration has an advantage that the effective magnetic flux amount per magnetic pole can be freely changed by changing the angle θ.

FIG. 5B shows still another embodiment of the internal magnet type rotor in which the center line of the magnetizing direction of the field magnet 121 is arranged in the radial direction of the rotor core 122. . In this arrangement, although the field magnet 121 is arranged inside the rotor core 122, an effective magnetic flux amount close to that of the surface magnet type rotor is obtained.

FIG. 5C is a sectional view of a main part of the internal magnet type rotor in a case where the sectional shape of the field magnet 131 is semi-cylindrical. In this embodiment, since the thickness of the center of the field magnet 131 is thicker than that at both ends, when the rotor 130 is incorporated in the magnet type brushless motor of the present invention and driven, the rotation of the rotor 130 in the air gap is performed. This has the advantage that the effective magnetic flux density distribution in the direction can be approximated to a sine wave.

In FIG. 1, the magnetic pole phases of the first rotor 2a and the sensor magnet 22 are fixed, and the second rotor 2b is connected to the first rotor 2a.
Can rotate relative to the first rotor 2a, and the magnetic pole of the second rotor 2b
The configuration is such that the rotor 2 is relatively displaced in the forward rotation direction of the rotor 2 with respect to the magnetic pole a. In the present invention, the combination of whether the three members of the rotors 2a and 2b and the sensor magnet 22 are fixed or rotatable is arbitrary.
The magnetic pole phases of b and the sensor magnet 22 may be fixed, and the magnetic pole of the second rotor 2b may be relatively shifted in the forward rotation direction with respect to the magnetic pole of the first rotor 2a during high-speed rotation. Also, the second rotor 2b and the sensor magnet 2
The magnetic pole phase of the second rotor 2b may be fixed, and the magnetic pole of the second rotor 2b may be relatively displaced in the reverse rotation direction with respect to the magnetic pole of the first rotor 2a during high-speed rotation.
Further, the magnetic pole phases of the first rotor 2a and the sensor magnet 22 are fixed, and the magnetic pole of the second rotor 2b is rotated in a direction opposite to the magnetic pole of the first rotor 2a at high speed rotation. It is good also as a structure shifted | deviated. As an example in which the first rotor 2a and the second rotor 2b are arranged so that the generated magnetic flux amounts are different, for example, in the state of FIG. 1A, the first rotor 2a and the second rotor 2b are arranged. When the ratio of the amount of interlinkage magnetic flux is 1: 2, the change ratio of the amount of magnetic flux interlinking with the field winding 12 is increased by the same magnetic pole shift operation as compared with the case where the ratio is 1: 1. be able to. Further, by providing a separate phase changing mechanism for the sensor magnet 22, the advance angle can be changed independently of the rotation speed at the time of low rotation and high rotation, and substantially at the time of low rotation and high rotation. It is also possible to adopt a configuration in which the advance angle does not change.

The phase of the combined magnetic poles of the first and second rotors 2a and 2b is shifted with respect to the magnetic poles of the first rotor 2a.
The mechanism shown in FIG. In FIG. 3, the first rotor 2a has a rotating shaft 2
1, the second rotor 2b is configured such that the rotating shaft 21 is inserted through a central shaft hole 321 so as to rotate around the rotating shaft 21 by a predetermined amount. A gap 5 of several mm is provided between the first rotor 2a and the second rotor 2b so that the magnetic pole shift operation is not hindered by the attraction and / or repulsion acting between the first and second rotors 2a and 2b. It is desirable. The governor fixing plate 33 is fixed to the rotating shaft 21, and four end holes 331 provided in the end face of the governor fixing plate 33 symmetrically in the vertical and horizontal directions at a central angle of 90 degrees, respectively.
41 is fitted. The governor 34 is a substantially arc-shaped component and has through holes 348 and 349 at both ends. Through hole 3
A rotation support shaft 341 is fitted to 48, and a movable shaft 342 is fitted to the through hole 349 to hold the governor 34. Further, four arc-shaped long holes 332 are provided point-symmetrically near each of the holes 331. On one end surface of the rotor core 8, four long grooves 322 are provided in the radial direction symmetrical in the vertical and horizontal directions at a central angle of 90 degrees, and the movable side shaft 342 is inserted into each of the long holes and each of the long grooves. At the same time, the four movable shafts 342 are connected to each other by a spring 343 so as to be attracted by their elastic force. When the rotation speed of the rotor 2 is low due to the tension of the spring 343, the movable side shaft 342 of the governor 34 as shown in FIG.
Is located closest to the rotating shaft 21 in the elongated hole 332. At this time, the same magnetic poles of the second rotor 2b and the first rotor 2a are arranged side by side. As the number of rotations of the rotor 2 increases, the governor 34 is moved by the centrifugal force as shown in FIG.
The shaft 342 on the movable side of the governor 34 opens in the state shown in FIG.
Moves toward the outer peripheral side along the elongated hole 332 of the governor fixing plate 33, and at the same time, the elongated groove 322 is displaced from the elongated hole 332 toward the outer peripheral side of the rotor 2 in the rotational direction. The insertion part of the long groove 322 of the shaft 342 is
The rotor core 8 is rotated in the direction of the arrow through
Can rotate in the direction of the arrow with respect to the first rotor 2a. Since the centrifugal force decreases as the rotation speed of the rotor 2 decreases, the governor 34 closes to the state shown in FIG.
Return to the position where the same magnetic poles a and 2b are arranged. Thus, the second
Of the rotating shaft 2 by a predetermined amount with respect to the first rotor 2a.
The mechanism for relatively rotating around 1 does not require external control and power, and is operated only by the centrifugal force acting on the components of the rotor 2. Therefore, the magnet type brushless motor is simple and easy and inexpensive. Can be controlled. Also, as described above, the rotor core 8 has the long groove 322.
The length of the axial dimension (L) from the long groove 322 to the governor 34 can be suppressed from increasing, and
By taking into account the acting centrifugal force and appropriately setting the spring constant of the spring 343 so that the above-mentioned magnetic pole shift operation occurs at a predetermined rotation speed, a high torque and a high rotation speed can be obtained in a wide rotation speed region as shown in an embodiment described later. Motor replacement efficiency can be obtained.

FIG. 6 is a perspective view of another embodiment of the present invention in which a main part of a magnet type brushless DC motor provided with a magnet rotor with a cylindrical cover is disassembled. 6, components having the same reference numerals as those in FIG. 1 indicate the same components. The two rotors 20a, 20b arranged in the magnet type brushless DC motor 60 of FIG. 6 are respectively provided on the circumferential surfaces of the ferromagnetic rotor cores 70a, 70b in the rotation direction with the first and second rotors through the air gap 16. The field magnets 61 and 62 are arranged in a number corresponding to the number of magnetic poles, and a non-magnetic cylindrical cover (for example, made of SUS304) is further disposed thereon to reinforce the field magnet. ing. Therefore, even when the rotor 20 is rotated at a high speed, the field magnet is not separated. Here, the cylindrical cover may be formed of a ferromagnetic material (for example, carbon steel or the like). Further, the cylindrical cover is formed by using the same material in which a ferromagnetic portion and a non-magnetic portion described in JP-A-8-331784 coexist and the ferromagnetic portion and the non-magnetic portion have different crystal structures. Is also good.

FIG. 7 shows another embodiment of the magnet rotor with a cylindrical covering used in the above-mentioned magnet type brushless electric motor 60. FIG.
In the magnet rotor 70 having a cylindrical cover, instead of the arc segment magnet as the field magnet 71, a radially anisotropic magnet or a multi-pole anisotropic magnet having an integral ring shape is used. The assembly of the child 70 can be easily performed.

(Embodiments A to D) In the magnet type brushless electric motor 50 of the present invention, Nd-Fe-B manufactured by Hitachi Metals, Ltd. is used as the first and second field magnets 31, 32.
-Based anisotropic sintered magnet: HS-30BV and the thickness of the air gap 6 being 0.5 mm, the above-mentioned magnetic pole shift mechanism accompanying an increase in the number of rotations, the effective reduction rate of one tooth and the advance angle Are simultaneously changed under the conditions of Table 1 below, and FIG. 8 shows the rotation speed-torque characteristics, and FIG. 9 shows the rotation speed-motor conversion efficiency. Here, the single tooth effective magnetic flux means the maximum interlinkage magnetic flux that flows from the magnet rotor to one magnetic pole of the armature. (Conventional example e) The second rotor is also fixed to the rotating shaft so that the same magnetic poles as the first rotor are arranged, and the advance angle is 5.5.
FIG. 8 shows the rotational speed-torque characteristics of the conventional magnet type brushless motor evaluated in the same manner as in the above embodiment except that the motor was fixed in degrees, and FIG. 9 also shows the rotational speed-motor conversion efficiency.

[0024]

[Table 1]

Referring to FIGS. 8 and 9 and Table 1 as a representative of the magnet type brushless motor of the embodiment A,
rpm. When the number of rotations is lower than 2, the advance angle at low rotation is 2
0 degrees and 1000 rpm. As described above, the advance angle at high rotation is set to 6 degrees when the rotation speed is high and the magnetic pole deviation is 28 degrees (maximum value). That is, when the rotational speed is 1000 rpm. If it is less than 1, the sensor advance angle is set to 20 degrees in a state where the magnetic poles of the first and second rotors 2a and 2b are aligned without phase shift. And
Rotation speed is 1000 rpm. At this time, the second rotor 2b rotates 28 degrees with respect to the first rotor 2a in the rotation direction of the rotor 2 by the action of the governor 34 due to the centrifugal force,
The phase of the combined magnetic pole of the first and second rotors 2a and 2b advances by half the phase of the magnetic pole of the second rotor 2b. Therefore, the advance angle is delayed accordingly. When the magnetic pole shift of the second rotor 2b reaches the maximum of 28 degrees, half of the magnetic pole shift is 14
The lead angle is delayed by 6 degrees to 6 degrees. At this time, the effective reduction rate of the single tooth effective magnetic flux was 34% (100% → 66%), and it was found that higher torque and motor exchange efficiency could be obtained in a wider rotational speed range than the conventional example E. Further, as shown in the drawings for Examples B, C, and D, it was found that higher torque and motor exchange efficiency could be obtained in a wider rotation speed range than that of the conventional example E. Further, the embodiments i, b,
Comparing C and D, it was found that the larger the advance angle at low rotation, the higher the torque and motor exchange efficiency over a wide rotation speed range.

As is clear from FIGS. 8 and 9, the magnet type brushless motor of the present invention has no load rotation speed without lowering the rated torque (7 Nm) and the maximum efficiency as compared with the conventional motor. (N _max ) could be increased to 2.8 times. In addition, high torque and motor exchange efficiency were obtained in a wide rotation speed range.

The magnitude of the magnetic pole deviation angle (θ: degree) is determined by determining the central angle of each magnetic pole of the n poles when a symmetrical n pole magnetic pole pattern is formed on the outer peripheral side of the first and second rotors. To (x:
Degree), it is preferable that x / 2 ≦ θ ≦ 0.8x. This is because when the rotation speed is less than (x / 2: degree), the reduction rate of the effective magnetic flux per tooth due to the magnetic pole shift operation accompanying the increase in the rotation speed is 3%.
This is because it is difficult to secure 0% or more, and if it exceeds (0.8x: degree), there is a high possibility that a rotational force in the opposite direction will be generated, which will hinder the magnetic pole displacement mechanism of the present invention. It is preferable that the lead angle (α: degree) is 0 <α ≦ x / 2. This is because the upper limit value is obvious from the definition of the lead angle, and the lower limit value can be set to a controllable lead angle that does not include 0.

In the above embodiment, the effective magnetic flux per tooth is 34%
Although an example in which the magnetic flux is reduced is described, according to the present invention, it is extremely easy to reduce the effective magnetic flux amount per tooth to 30% or more. More preferably, the reduction rate is 40% or more,
Particularly preferably, it can be set to 50%. Also,
In the above aspect of the present invention, the case where the same symmetric 8-pole magnetic pole pattern is formed on the outer peripheral surfaces of the first and second rotors is described, but both may have the same asymmetric magnetic pole pattern.
Further, the number of magnetic poles is not limited, but is very useful for those having preferably 2 to 128 poles, more preferably 4 to 32 poles. Further, the first and second rotors may have different magnetic pole patterns. Further, for example, by setting the ratio of the amount of interlinkage magnetic flux generated in a state where the same magnetic poles of the first and second rotors are arranged to different appropriate values, the rotation speed is increased and one magnetic pole shift operation is performed. Thus, a greater change in the amount of interlinkage magnetic flux can be achieved. Also,
In the above aspect of the present invention, the amount of interlinkage magnetic flux of the magnet type brushless motor is reduced by rotating two of the coaxial rotors relative to one another with a change in the number of rotations. The present invention can also be configured by fixing one or two or more rotors to a rotation shaft using three or more rotors and relatively rotating the remaining rotors. In the present invention, the shape, size, number, etc. of the field magnets are not limited, and the inner or outer peripheral surface of the rotor core is formed so that different magnetic poles are formed alternately in the outer peripheral surface rotation direction of the rotor. Arbitrary field magnets can be placed on top.

[0029]

As described above, the magnet-type brushless motor of the present invention can obtain a high torque at a low rotation speed as in the conventional motor, and is nearly three times as high as the conventional motor. It can be used with high torque up to the rotation speed and with high exchange efficiency. Furthermore, since the field magnet is prevented from peeling off at the time of high-speed rotation, it becomes useful, for example, as a drive motor for an automobile, which can be used in place of an internal combustion engine.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part showing an embodiment of a magnet type brushless motor of the present invention provided with an internal magnet type rotor, in which there is no magnetic pole shift (A) and a magnetic pole shift state (B).
Is shown.

FIG. 2 is a view for explaining the advance of the magnetic pole of the field magnet in the magnet type brushless motor of the present invention, showing a state where there is no magnetic pole shift (A) and a magnetic pole shift state (B).

FIG. 3 is an exploded view showing a mechanism for changing a phase of a combined magnetic pole of the first and second rotors with respect to a magnetic pole of the first rotor with rotation of the rotor in the magnet type brushless motor of the present invention. It is a perspective view, (A) is a low rotation speed, (B)
At high rotation speed.

FIG. 4 is a view showing another embodiment of the internal magnet type rotor used in the present invention.

FIG. 5 is a sectional view of a main part showing still another embodiment of the internal magnet type rotor used in the present invention. FIG. 5 (A) shows that the magnetization direction of the field magnet is at an angle with respect to the radial direction of the rotor core. (B) is the case where the center line of the magnetizing direction of the field magnet is arranged in the radial direction of the rotor core, and (C) is the case where the field magnet is in the shape of a kamaboko. is there.

FIG. 6 is an exploded perspective view of a main part showing an embodiment of a magnet type brushless motor of the present invention using a magnet rotor with a cylindrical cover, in which there is no magnetic pole shift (A) and a magnetic pole shift state (B). ).

FIG. 7 is a view showing another embodiment of a magnet rotor with a cylindrical cover.

FIG. 8 is a diagram illustrating an example of a rotation speed-torque characteristic of a magnet type brushless electric motor.

FIG. 9 is a diagram showing an example of the rotational speed-motor conversion efficiency of a magnet type brushless motor.

FIG. 10 is an output characteristic diagram of an internal combustion engine with a transmission.

FIG. 11 is a characteristic diagram of a conventional brushless DC motor.

FIG. 12 is a view showing a rotor of a conventional magnet type brushless electric motor.

[Explanation of symbols]

1 stator, 2 rotors, 3,503 field magnets,
4,40 magnetic poles, 5,15 intervals, 6,16,506
Air gap, 7, 8, 70a, 70b, 72, 507 rotor core, 11 stator magnetic pole, 12 field winding, 20, 70
Magnet rotor with cylindrical cover, 21 axis of rotation, 22 sensor magnet, 31, 61 First field magnet, 32, 62
Second field magnet, 33 fixing member, 34 governor, 5
0,60 magnet type brushless motor, 2,100,11
0, 120, 130 Internal magnet type rotor, 111, 12
1,131 Field magnet, 112, 122, 132 Rotor core, 113, 123, 133 Rotation axis, 18, 7
8 Cylindrical cover, 308 thin plates, 309 laminate, 321
Shaft hole, 322 long groove, 331 hole, 332 long hole, 3
41 Rotation support shaft (fixed shaft), 342 Movable side shaft, 343
Elastic member, 348, 349 through hole, 500 surface magnet type rotor, 502 axis of rotation.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Mita 5200 Mikajiri, Kumagaya-shi, Saitama Magnetic Materials Research Laboratory, Hitachi Metals, Ltd.

Claims (2)

[Claims] 1. A stator having a plurality of stator magnetic poles and a winding for generating a rotating magnetic field in the stator magnetic poles, a rotating shaft and a plurality of stator magnetic poles provided on the rotating shaft. A rotor having a rotating field magnet, and a magnet type brushless motor having a control circuit for detecting a position of a magnetic pole of the rotor with respect to a stator and supplying a current to the winding according to the position. A rotor disposed around a rotation axis and having magnetic poles of different polarities sequentially arranged in a rotation direction, and a cylinder disposed on a peripheral surface of the first field magnet. A first rotor having a cover and a second field in which magnetic poles which are rotatable relative to the first rotor and which are arranged around a rotation axis and have sequentially different polarities in the direction of rotation are arranged. Magnet for magnet and cylinder arranged on the peripheral surface of this second field magnet And a second rotor having a shape-like cover, wherein the first and second rotors are opposed to the stator magnetic poles, and the first and second rotors have a combined magnetic pole of the first and second rotors. A magnet type brushless motor having a mechanism for changing a phase with respect to a magnetic pole of a first rotor as the rotor rotates. 2. A stator having a plurality of stator magnetic poles and a winding for generating a rotating magnetic field in the stator magnetic pole, a rotating shaft and a plurality of stator magnetic poles provided on the rotating shaft. A rotor having a rotating field magnet, and a magnet type brushless motor having a control circuit for detecting a position of a magnetic pole of the rotor with respect to a stator and supplying a current to the winding according to the position. In the rotor, a field magnet is embedded in a first rotor core disposed around a rotation axis, and magnetic poles having different polarities are sequentially arranged in the rotation direction of the first rotor core. First
And a field magnet is embedded in a second rotor core disposed around the rotation axis, and magnetic poles having different polarities are sequentially arranged in the rotation direction of the second rotor core. A second rotatable relative to the first rotor;
Wherein the first and second rotors are opposed to the stator magnetic poles, and the phase of the combined magnetic poles of the first and second rotors is changed by the first rotor. A magnet-type brushless motor having a mechanism for changing the magnetic poles with the rotation of the rotor.