JPH02184253A - Electric motor - Google Patents

Abstract

PURPOSE:To reduce the irregularity of rotation by a method wherein a distance between the imaginary cylindrical surface of a plurality of projections of a stator and the inner peripheral surface of both circumferential ends of a plurality of permanent magnets of a rotor is made larger than a distance between the imaginary cylindrical surface and the inner peripheral surface of the circumferential central parts of the permanent magnets. CONSTITUTION:Four pieces of fixed members 26, consisting of a nonmagnetic material such as aluminum or the like, are provided in the cylindrical part 15 of a casing 4 at the outside positions of an imaginary cylindrical surface F formed by connecting the outermost peripheral surfaces of respective salient- poles P1-P6 of a stator 8 to fix respective permanent magnets 16 of a rotor 3. A distance between the cylindrical surface and the inner peripheral surface of both circumferential ends of the magnets 16 is made larger than a distance between the cylindrical surface and the inner peripheral surface of the circumferential central parts of the magnets 16.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an electric motor used to drive a fan device such as a cross flow fan installed in an indoor unit of an air conditioner. .

(Prior Art) In recent years, fan devices such as cross-flow fans installed in indoor units of air conditioners have been designed to directly connect the rotor of DC flashless smoke to the fan rotor of the cross-flow fan. , attempts have been made to downsize the device.

A specific example of such a device is, for example, Utility Model Application No. 61-1780.
It is described in Japanese Patent No. 95, and the device is schematically shown in FIG. In the figure, 80 is a fan rotor of a cross flow fan, and a rotor 83 having a ring-shaped permanent magnet 82 is fixed to one side plate 81 of the fan rotor 80.

On the other hand, a cylindrical fixed support shaft 85 is erected on the support frame 84 facing the side plate 81, and a stator 86 is fixed to the outer periphery of the distal end side of the fixed support shaft 85. The above-mentioned permanent magnet 82 surrounds it. The fan rotor 80 has rotating support shafts 8 at its both end axis positions.
7 and 88 are respectively erected, and these rotational support shafts 87,
88 is rotatably supported via bearings 89 and 90. By controlling the energization of the coil 91 of the stator 86 to form a rotating magnetic field, a rotational force is induced on the rotor 83, thereby rotationally driving the fan rotor 80.

(Problem to be Solved by the Invention) By the way, in the device having the above configuration, the ring-shaped permanent magnet 8
2 is magnetized so that N poles and S poles appear alternately in the circumferential direction of its inner peripheral surface. However, with this configuration in which different poles are formed alternately within the same plane, it is difficult to obtain a strong coercive force when the shape is made small, and the magnetic flux density distribution is also poor, making it difficult to obtain smooth rotation. There is a problem. Therefore, it is conceivable to adopt a structure in which the above permanent magnets are divided into individual poles and arranged circumferentially around the outer periphery of the stator. In this case, the inner circumferential surface of each permanent magnet is an arcuate surface along the circumference concentric with the stator, and there is a uniform air gap between the inner circumferential surface of each permanent magnet and the outer circumferential surface of the stator over the entire circumference. However, in such a configuration, there is a problem in that rotational unevenness is likely to occur. it is,
For example, when one of the radially extending salient poles in the stator is located at a position in the circumferential direction between the ends of adjacent permanent magnets, the outermost peripheral part of the salient pole is close to the inner peripheral surface of each end of the permanent magnet. As a result, a leakage magnetic flux is generated between the respective ends via the outermost circumferential portion of the salient pole, and as a result, a force is generated that tries to fix the rotor in the above position, and such This is because the force causes a rotational state in which greater cogging occurs.

In addition, when using a split type permanent magnet as described above,
It is necessary to assemble each permanent magnet to the rotor casing by gluing, etc. At this time, it is difficult to achieve accurate assembly, or the assembly process becomes complicated. There is also.

The present invention has been made in view of the above, and its purpose is to provide an electric motor using split permanent magnets that can reduce uneven rotation and improve assembly workability. It is in.

(Means for Solving the Problems) Therefore, the electric motor according to the first aspect of the present invention includes a stator 8 having a plurality of radially extending salient poles P1 to P6, and a stator 8 that is surrounded from the outside in the radial direction. The electric motor is provided with a rotor 3 having a plurality of permanent magnets 16 circumferentially arranged at certain positions, and each permanent magnet 16 is configured such that inner peripheral surfaces adjacent to each other in the circumferential direction have different poles. , each of the above salient poles P
The distance between the virtual cylindrical surface F on which the outermost peripheral surfaces of 1 to P6 are located and the inner peripheral surface of each permanent magnet 16 on both ends in the circumferential direction is defined as the distance between the virtual cylindrical surface F and each permanent magnet l6
The distance between the inner circumferential surface and the inner circumferential surface on the circumferential center side is set to be greater than

Further, in the electric motor according to the first aspect, each permanent magnet 16 is disposed along the cylindrical inner peripheral surface of the casing 4 of the rotor 3. The outer circumferential surface of the permanent magnet 16 is formed by an arcuate surface having approximately the same radius as the cylindrical inner circumferential surface, while the inner circumferential surface of each of the permanent magnets 16 is formed by an arcuate surface having a radius larger than the radius.

Further, in the electric motor according to the second claim, an inner periphery of each permanent magnet 16 disposed along the cylindrical inner circumferential surface of the casing 4 on the circumferential end side thereof is provided. A fixing member 26 made of a non-magnetic material that comes into contact with the surface and prevents movement of the permanent magnet 16 is provided in the casing 4 at a position outside the virtual cylindrical surface F.

Further, in the electric motor according to a fourth aspect of the present invention, the outer circumferential surface of each permanent magnet 16 is arranged within the cylindrical inner circumferential surface of the casing 4 of the rotor 3 so that each of the permanent magnets 16 is arranged along the cylindrical inner circumferential surface of the casing 4 of the rotor 3. It is formed by an arcuate surface with approximately the same radius as the circumferential surface, and
The inner circumferential surface of each of the permanent magnets 16'' is formed into a concentric circular arc surface with a radius smaller than the above radius, while the outer circumferential surface 30 extending in the circumferential direction of the salient pole PI-P6 is formed into a concentric circular arc surface. Each of the above permanent magnets 16゛ at both circumferential ends of poles P1 to P6
The distance from the center part in the circumferential direction is larger than that at the center part in the circumferential direction.

(Function) In the electric motor according to the first claim, the salient poles Pi-P
6, for example, the salient pole P1 is connected to the adjacent permanent magnet 16.1.
6, the outermost circumferential portion of the salient pole P1 is located at a position radially away from the inner circumferential surface of the end of each permanent magnet 16, 16. The leakage magnetic flux density between the respective ends via the pole P1 is reduced, and as a result, the fixing stopping force for the salient pole PI is reduced, so cogging is reduced and rotational unevenness is reduced.

In the electric motor according to the second aspect of the invention, the inner circumferential surface of each permanent magnet 16 is configured to have a larger radius than the outer circumferential surface, for example, a crescent-shaped cross section, and these are formed into a cylindrical shape in the casing 4 of the rotor 3. By assembling along the inner circumferential surface, the inner circumferential surface of each permanent magnet 16 on the circumferential center side becomes a virtual cylinder in which the outermost circumferential surface of each of the salient poles P1 to P6 of the stator 8 is located. It is located at a predetermined distance from the surface F, and the distance from the virtual cylindrical surface F of the inner circumferential surface of each permanent magnet 16 on both ends in the circumferential direction is as follows:
If the assembly is larger than the center side in the circumferential direction, it will be in a state. In this way, there is no need for precise positioning work for each permanent magnet 16 (it can be assembled by a simple work of aligning it with the cylindrical inner peripheral surface of the casing 4, so the work can be easily done). be able to.

Further, in the electric motor according to the third aspect, a fixing member 26 made of a non-magnetic material is provided in a space formed outside the virtual cylindrical surface F, so that each permanent magnet 16
can be fixed, eliminating the need for complicated assembly operations such as gluing, thus improving assembly workability.

Further, in the electric motor according to the fourth aspect, the stator 8
The outer circumferential surfaces 30 of the salient poles P1 to P6 are configured such that the distance from each of the permanent magnets 16'' at both ends of the salient poles P1 to P6 in the circumferential direction is larger than that at the center in the circumferential direction. On the other hand, by assembling the permanent magnet 16' having an arc-shaped inner peripheral surface along the inner surface of the casing 4 of the rotor 3, the periphery of the outer peripheral surface 30 of each salient pole P1 to P6 of the stator 8 is The center part in the direction is assembled in such a state that the distance from the inner circumferential surface of each permanent magnet at 16 degrees is larger than that at the center part in the circumferential direction. −
Since the outer circumferential surface 30 of P6 may have the above-mentioned specific shape,
Productivity improves.

(Embodiments) Next, specific embodiments of the electric motor of the present invention will be described in detail with reference to the drawings.

FIG. 4 shows an assembled sectional view of a DC brushless morph type electric motor according to an embodiment of the present invention, and this electric motor is connected to one side of the fan rotor 1 of a cross flow fan used in an indoor unit of an air conditioner. It is assembled to the side plate 2 of. In the figure, reference numeral 3 denotes a rotor in the electric motor, and on the vertical surface 5 of the fan rotor 1 in the approximately cup-shaped casing 4 of the rotor 3, there is a rotor 3 located at the center of the fan rotor 1 side. An extending cylindrical connecting portion 6 is formed. And the above fan rotor 1
A connecting member 7 made of synthetic rubber or the like is attached to the center of the side #Ii2, and by press-fitting the cylindrical connecting portion 6 into the axial through hole of the connecting member 7, the above-mentioned times, The trochanter 3 has been assembled to the fan rotor 1. The connecting member 7 has a vibration-proofing function for attenuating the propagation of vibrations caused by rotational vibration in the fan rotor 1.

On the other hand, in the figure, 8 is a stator, and 9 is an end bracket that is fixed to the fan housing in the indoor unit, and the end bracket 9 has a midway portion of a fixed shaft 11 that is erected at the center of the face plate portion 10. The stator 8 is fixed to the stator 8. The first bearing 12 press-fitted into the cylindrical connecting portion 6 and the vertical surface 5 of the casing 4
By inserting the distal end side of the fixed shaft II into the second bearing I4, which is press-fitted into the short cylindrical bearing mounting portion 13 extending from the center position to the side opposite to the fan rotor 1, the fixed shaft 11 rotatably supports the rotor 3 and fan rotor 1, and a permanent magnet 16, which will be described later, is disposed on the inner peripheral surface of the cylindrical portion I5 of the casing 4.
is configured to face the outer peripheral surface of the stator 8.

The end bracket 9 has a face plate portion 10 and a surrounding wall 21 formed by sheet metal processing.
A circuit board 22 having a DC brushless morph control circuit is disposed in the space surrounded by the DC brushless morph. On this circuit board 22, in addition to a Hall element H1 as a magnetic field detection element and a power transistor Q, electronic components such as a capacitor, a resistor, and a control IC are mounted. High ones can be stored in a narrow space by being mounted horizontally, and among the electronic components mentioned above, the power transistor Q, which generates a large amount of heat, is mounted on the outer peripheral side of the circuit board 22 and mounted on the end bracket 9. It is attached using a spring clip 23 so as to be in close contact with the face plate portion IO.

That is, the end bracket 9 is configured to also function as a heat sink for the power transistor Q. Further, a bearing fixing spring 24 is attached to the tip of the fixed shaft 11, which comes into contact with the left end surface of the inner ring of the first bearing 12, in order to prevent the fixed shaft 11 from coming off to the right in the figure. There is.

FIG. 1 shows a sectional view taken along the line I--I in FIG. 4. As shown in the figure, the stator 8 is formed in a shape that extends radially and has six salient poles P1 to P6, each of which is wound with an excitation coil 25...25. It is configured to be circumferentially surrounded from the outside in the radial direction by four substantially arc-shaped permanent magnets 16 of the same shape made of anisotropic ferrite. Each of the permanent magnets 16 . . . 16 is magnetized so that the inner and outer circumferential surfaces thereof have different poles, and the inner circumferential surfaces adjacent to each other in the circumferential direction have different poles. The outer peripheral surface of each permanent magnet 16...16 is an arcuate surface having approximately the same radius as the inner peripheral surface of the cylindrical portion 15 of the casing 4 located concentrically with the stator 8, and a quarter of the circumference of the above radius. The inner circumferential surface of each permanent magnet 16... It is formed by an arcuate surface whose radius is approximately twice the radius of . Therefore, as shown in the figure, each permanent magnet 1
6...16 are disposed along the inner circumferential surface of the cylindrical portion 15, the stator increases from the radial center to both ends of the inner circumferential surface of each permanent magnet 16...16. The distance from the virtual cylindrical surface F that connects the outermost peripheral surfaces of each of the eight salient poles e1 to P6 gradually increases.

Furthermore, in the above configuration, the cylindrical portion 15 of the casing 4
Four fixing members 26 made of a non-magnetic material such as aluminum are placed at positions outside the virtual cylindrical surface F within the inner part.
-26 are provided, and each permanent magnet 16...16 is fixed with these fixing members 26...26. That is, in each of the permanent magnets 16, . Each of the fixing members 26 .
The end portions of the permanent magnets 6 and 16 are clamped to provide a fixed assembly in which movement of the permanent magnets 16 and 16 in the radial and circumferential directions is prevented. Although FIGS. 2 and 3 show a plan view and a front view of the fixing member 26, respectively, the lower end protrusion 27 shown in FIG. 3 is attached to the casing 4 as shown in FIG. Its position relative to the casing 4 is fixed by fitting it into a fitting hole in the vertical surface 5 of the casing 4.

Next, the operating state of the electric motor configured as described above will be explained.

The Hall elements H described above are arranged on the outer periphery of each of the three adjacent salient poles P1, P2, and P3 in the stator 8, and these Hall elements H cause the rotor 3 to
Detects changes in the magnetic field strength from the permanent magnet 16 according to the rotational position of the permanent magnet 16. In response to the detection signal, a drive signal is generated by the control IC at a predetermined timing, and thereby the energization of each magnetic pole coil 25...25 is periodically controlled to generate a rotating magnetic field on the stator 8 side. be done. This rotating magnetic field causes the rotor 3 to rotate, and the rotation of the rotor 3 is transmitted to the fan rotor 1, so that the fan rotor 1 is rotationally driven.

In such rotational drive, cogging is particularly reduced in the above-mentioned device, so that an operating state with less vibration can be maintained. This is due to the shape of each permanent magnet 16...16 as described above.
5 (a) to (f
) is a schematic diagram of the magnetic flux distribution in the above device, and FIGS. 6(a) to 6) show each permanent magnet 16'... A schematic diagram of the magnetic flux distribution in a conventional device configured with an arcuate surface along the surface is shown, and the differences between these will be explained next.

First, with reference to FIGS. 6(a) to 6(f), changes in magnetic flux distribution due to rotation of the rotor by 3 degrees in the conventional device will be explained.

The six salient poles of the stator 8° are arranged clockwise from P1 to P in the figure.
6. Move the four permanent magnets clockwise to N1, Sl, N2, N
2 (Nl and N2 are magnetized with the N pole on the inner circumference side, and Sl and N2 are magnetized with the S pole on the inner circumference side), then the 6th
The rotational position where the centers of the salient pole P1 and the permanent magnet N1 shown in FIG.
At the position of 10°), the maximum magnetic flux is generated at the salient poles P1 and P4, and the magnetic flux slightly less than the maximum magnetic flux is generated at the salient poles P2, P3, P5, and P6. The magnetic flux entering the salient pole P1 from the permanent magnet N1 passes through the salient pole P2 and enters the permanent magnet S1.
However, since the salient pole P2 is not located at the center position of the permanent magnet SL, the magnetic flux is small, and therefore a force acts to attract the salient pole P2 to the center position of the permanent magnet S1.

In other words, a counterclockwise torque acts on the rotor 3'. Similarly, a clockwise torque acts on the salient pole P3, and these forces are balanced, but if it moves even slightly to the left or right, the balance will be lost and an even stronger attraction force will act in the direction of the movement. Become. Similarly, the same effect acts on the salient poles P5 and P6, so these sides are also in an unstable state. Next, the rotor 3'' rotates 15 degrees clockwise from the above, and when it comes to the position shown in FIG. 6(b), the salient pole P1 changes to the salient pole P6,
Further, a magnetic flux is generated that flows from the salient pole P4 to the salient pole P3. At this time, salient poles P2 and P5 are permanent magnets Nl and S, respectively.
l, located between N2 and N2, generates a magnetic flux flowing from the adjacent north pole to the south pole through the vicinity of the outermost periphery of each salient pole P2 and P5, and this magnetic flux causes excitation in each salient pole P2 and P5. The leakage magnetic flux does not reach the coil winding position. Such leakage magnetic flux acts as a force that fixes each salient pole P2, P5 against rotation. On the other hand, salient poles P1 and P6, P3 and P
Since magnetic flux close to the maximum magnetic flux density is uniformly generated in each of the magnets 4, the torque that acts as a rotational force is in a state where it does not work.

FIG. 6(C) shows the position state where the rotation angle of the rotor 3' is 30 degrees, and at this time, the salient poles P3 and P6 are in the position where they coincide with the centers of the permanent magnets S1 and N2, and the above-mentioned The magnetic flux distribution is almost the same as that at the position where the rotation angle is 0 degrees, and therefore, similar to the above, a stronger rotational force is generated in the direction of movement from this position to either the left or right. From the above, when the rotor 3'' rotates clockwise from the 0 degree position to the 30 degree position, the rotational force accelerates toward the 15 degree position from 0 degree to 15 degree. acts, a stopping force acts at the 15 degree position, and further a deceleration force occurs from 15 degrees to 30 degrees.

FIGS. 6(d) to (f) show the subsequent rotation angle position of 45 degrees,
The magnetic flux distributions at 60 degrees and 75 degrees are shown, but as shown in these figures, the above magnetic flux distribution states of 0 degrees and 15 degrees are repeated every 15 degrees, so at 30 degrees. The rotational state is such that the acceleration force, stopping force, and deceleration force are repeated each time, resulting in uneven rotation, that is, cogging.

On the other hand, in the apparatus of the above embodiment shown in FIGS. 5(a) to 5(f), the rotation angle position of the rotor 3 is 0 degrees, 30
At 15 degrees, 60 degrees, the magnetic flux distribution is almost the same as that of the conventional device, but at 15 degrees, 45 degrees, and 75 degrees, for example, at 15 degrees, permanent magnet N1 and 3
Since the outermost circumferential surface of the salient pole P2 located between the salient pole P2 and the
The leakage magnetic flux through is reduced. Therefore, the fixing force, that is, the force that acts as a stopping force at the 15 degree position becomes weaker, and as a result, cogging becomes smaller and rotational unevenness is reduced. Therefore, it is possible to reduce the generation of noise and vibration in the fan device driven by this electric motor compared to the conventional case.

Furthermore, in the above device, each permanent magnet 16 is formed to have a crescent shape in cross section, so that the circumferential end side of each permanent magnet 16 is farther away from the stator 8 than the center part, and the outer peripheral surface is shaped like a cylinder of the casing 4. It is composed of a circular arc surface having the same diameter as the inner peripheral surface of the portion 15.

Therefore, by assembling each permanent magnet 16 along the inner circumferential surface of the cylindrical portion 15, the inner circumferential surface of each permanent magnet 16 on the circumferential center side is
The outermost peripheral surfaces of ~P6 are located at a predetermined distance from the virtual cylindrical surface F, and each permanent magnet 1
The virtual cylindrical surface F of the inner circumferential surface on both ends in the circumferential direction in 6
The distance from the center part in the circumferential direction is larger than the center part side in the circumferential direction. In this way, there is no need for precise positioning work for each permanent magnet 16, and assembly can be accomplished by simply positioning the permanent magnets 16 along the cylindrical inner circumferential surface of the casing 4, making the work easy. It's something you can get.

In addition, in the above, the fixing member 26 made of a non-magnetic material is provided in the internal space of the casing 4 located outside the virtual cylindrical surface F, and each permanent magnet 16 can be fixed with this, so it is possible to This eliminates the need for complicated assembly work, and therefore the ease of assembly work has been improved.

Furthermore, by adopting the split permanent magnet configuration as described above, it is possible to use anisotropic magnets with strong magnetic properties made of, for example, anisotropic ferrite, which improves motor characteristics and allows for miniaturization. .

Although specific embodiments of the present invention have been described above, the above embodiments do not limit the present invention, and various changes can be made within the scope of the invention. For example, in the above embodiments, Although an example is shown in which the permanent magnet 16 has a crescent-shaped cross section, other configurations are also possible, such as having the inner peripheral surface side flat. Further, although the above embodiment is configured as a DC brushless morph type electric motor, the present invention can be applied to other types of electric motors.

Next, another embodiment of the present invention will be described with reference to FIG. 7 and subsequent figures. As in the case of FIG. 4, FIG. 7 shows an assembled cross-sectional view of a DC brushless motor type electric motor, and in the drawings from FIG. Parts indicate the same or equivalent parts.

In FIG. 7, an electric motor is connected to the right end of the fan rotor 1, and the fixed shaft 11 of the stator 8 of the electric motor is connected to the connecting portion 6 of the casing 4 by a first bearing 35 and a second bearing 36. A bearing mounting portion 13 is rotatably supported. The outer ring 37 of the first bearing 35 on the side of the fan rotor 1 is fitted into the connecting portion 6 with a clearance, and the outer ring 37 of the first bearing 35 on the side of the force cylinder 2
8 is press-fitted into the bearing mounting portion 13 and fixed. A cylindrical spacer 39 is provided between both bearings 35,36. For example, a wave spring 40 or the like is installed between the first bearing 35 and the connecting portion 6, and the spring force of the wave spring 40 moves the outer ring 37 of the first bearing 35 to the right in the figure toward the second bearing 3.
It is energized towards 6. The spring force pushing the outer ring 37 is transmitted from the inner ring 41 of the first bearing 35 to the inner ring 42 of the second bearing 36 via the spacer 39, thereby urging the inner ring 42 to the right. Therefore, the spring force of the wave spring 40 applies preload to both bearings 35 and 36 at the same time.

At the right end of the fixed shaft 11 in the figure, an end bracket 43 made of aluminum casting, which will be described in detail later, is attached to the fixed shaft 11.
is fixed perpendicular to.

With the stator 8 fixed to the fixed shaft 11, when the fixed shaft 11 is inserted into both bearings 35 and 36 and assembled into the assembled state shown in the figure, the rotor 3 is rotatably supported by the fixed shaft 11, and the fan It has a structure that rotationally drives the rotor l.

Next, a structure for fixing the electric motor to the indoor unit of the air conditioner will be explained. The substantially plate-shaped end bracket 43 has a substantially cylindrical fixing portion 44 that is concentric with the fixed shaft 11 and continues integrally with the end bracket 43, for example, by aluminum casting. The fixing portion 44 extends in the axial direction from the middle of the connecting portion 6 to near the right side of the drive circuit board 22 so as to surround the heavy central portions of the motor such as the rotor 3 and stator 8 . Therefore, the fixing portion 44 naturally extends in the axial direction including the center of gravity of the electric motor. Further, a gap 45 is provided between the fixed portion 44 and the casing 4 of the rotor 3 over the entire circumference so that the rotor 3 can rotate.

A substantially cylindrical vibration isolating rubber 46 that is continuous over the entire circumference is fixed to the outer circumferential surface of the fixing portion 44 by, for example, adhesion or baking. Further, the outer circumferential surface of the vibration isolating rubber 46 is similarly fixed to the fixing case 47. The fixing case 47 has a bottomed cylindrical shape with an open left end surface in the figure. Further, an annular groove 48 is formed in a portion of the fixing case 47 corresponding to the vicinity of the center of gravity of the electric motor, and the bottom frame 49 is fixed to the fixing case 47 at this annular groove 48 portion. This bottom frame 49 is connected to the main body (not shown) of the indoor unit to support the electric motor.

With the support structure described above, the axis of the electric motor does not go out of alignment, and it becomes easy to align the axis of the fan rotor 1 with the axis of the electric motor. Moreover, a soft rubber with low hardness can be used for the substantially cylindrical vibration isolating rubber 46, and the vibration isolating effect is enhanced. therefore,
Vibration and noise caused by the electric motor are reduced, resulting in a low-vibration, low-noise indoor unit.

In FIG. 8, which is a side view of the stator 8, the stator 8 has six salient poles Pi-P6 around which excitation coils 25 (FIG. 1) are wound, as in the case of FIG. ing. As will be described in detail later, this embodiment is characterized by the shape of the outer circumferential surface 30 of these salient poles Pi-P6. On the other hand, this stator 8 is circumferentially surrounded from the outside in the radial direction by four substantially circular arc-shaped permanent magnets 16'...16' of the same shape made of anisotropic ferrite, that is, as shown in FIGS. The configuration is similar to that shown in FIG. 6. The permanent magnets 16', . . . 16' are similar to those shown in FIG. 6, in which the outer and inner peripheral surfaces are formed by concentric arcuate surfaces. Each permanent magnet 16°...16
" are magnetized so that the inner and outer circumferential surfaces have different poles, and the inner circumferential surfaces adjacent to each other in the circumferential direction have different poles. The outer circumferential surface 3 of each of the salient poles P1 to P6 is
0 is formed such that its circumferential center is closest to the 16° inner circumferential surface of the permanent magnet, and both circumferential ends are farthest from the inner circumferential surface.

The detailed shape of this outer circumferential surface 30 is symmetrical to the center line 31 of each of the salient poles P1 to P6 over a width W from a virtual reference line 32 to a maximum thickness L, as represented by the salient pole P1 in FIG. It stands out even. This change in the thickness of the outer circumferential surface 30 is such that the thickness Lχ at a point 34 moved by χ from the virtual reference line 33 in the width direction is Lχ=Lxsin(180/W)×χ...
- It is made to change according to the sine curve expressed by (1). Therefore, the air gap, which is the distance between the permanent magnets 16'...16' (FIG. 7) of the rotor 3 and the outer circumferential surface 30, is calculated by the sine curve of the above equation (1) from the minimum air gap state, for example. increases smoothly along the line to reduce torque unevenness and noise of the electric motor.

Next, the operating state of the electric motor according to this embodiment will be explained. In this embodiment as well, as in the case of FIG. 1, the energization of each magnetic pole coil 25, . . . , 25 is periodically controlled to generate a rotating magnetic field on the stator 8 side.

This rotating magnetic field causes the rotor 3 to rotate, and this rotor 3
The rotation of the fan rotor 1 is transmitted to the fan rotor 1, and the fan rotor 1 rotates.

In such a rotational drive, the embodiments shown in FIGS. 7 and 8 have magnetic flux distribution characteristics that reduce cogging due to the shape of the salient poles P1 to P6 of the rotor 3, and therefore maintain an operating state with less vibration. occurs. Regarding the improvement of this magnetic flux distribution characteristic, FIG. 9 is a schematic diagram of the magnetic flux distribution when the outer circumferential surface 30 has the improved stator 8, and FIG. This will be explained by comparing it with a certain figure 10. 9 and 10 both illustrate the position at a rotation angle of 15 degrees, but the above-mentioned FIG. 5(b) and FIG. The polarity is reversed.

First, in the conventional figure 10, salient pole P6 to Pl and salient pole P3
A magnetic flux 60.60 that causes rotational force is generated at two locations from P4 to P4, and a relatively large leakage magnetic flux 61.61 is generated at two locations at salient poles P2 and P5, and furthermore, salient poles P1 and P6
A small leakage magnetic flux 62.62 is generated at two locations: between the ends of the salient poles P3 and P4, and between the ends of the salient poles P3 and P4. In this state, the rotational force due to the magnetic flux 60.60 at two locations is the leakage magnetic flux 60 at four locations.
The fixation force due to 1.62 is reduced by the bone.

Next, in FIG. 9 for this embodiment, from salient pole P6 to Pi
Magnetic flux 6 that causes rotational force at two locations between salient poles P3 and P4
3.63 occurs, relatively small leakage magnetic flux 64.64 occurs at two locations of salient poles P2 and P5, and leakage magnetic flux occurs between the ends of salient poles P1 and P6 and between the ends of salient poles P3 and P4. has hardly occurred. In the state shown in FIG. 9, the fixing force is reduced by the amount by which the leakage magnetic flux 64.64 becomes smaller than the leakage magnetic flux 61.61 in FIG. 10 and by the amount by which the leakage magnetic flux 62.62 disappears. As a result, the force acting as a stopping force becomes weaker at a rotation angle of 15 degrees, for example. This stopping force is generated at the rotation angle of 15 degrees, 45 degrees, and 75 degrees as the motor rotates, so when the stopping force becomes weaker, cogging becomes smaller and uneven rotation is reduced. becomes.

Therefore, it is possible to reduce the generation of noise and vibration in the fan device driven by this electric motor compared to the conventional case.

The outer circumferential surface 30 of each of the salient poles P1 to P6 is not only thick at the center in the circumferential direction and thinner at both ends, but also formed by the sine curve of equation (1) above. Since the air gap between the surface 30 and each permanent magnet 16' increases and decreases smoothly as the rotor 3 rotates, torque unevenness is further reduced, and low noise of the -layer heavy machine is achieved.

Further, in this embodiment, the outer circumferential surface 30 of each salient pole P1 to P6, which can be relatively easily formed into an arbitrary shape, is formed into a shape along the sine curve of the above equation (1), Since there is no need to perform special processing on the permanent magnet 16°, which is difficult to process, productivity is improved.

In this embodiment, the outer circumferential surface 30 is formed by a sine curve according to the above formula (1), but it is not necessarily limited to this shape, and may have other shapes that are thick at least at the center in the width direction and thin at both ends You may also do so. It is also possible to combine the outer peripheral surface 30 with the crescent-shaped permanent magnet 16 shown in FIG.

(Effects of the Invention) As described above, in the electric motor according to the first claim of the present invention, the salient pole located between adjacent permanent magnets in the circumferential direction is freed from the permanent magnet that is intended to fix the salient pole. Since the magnetic force is reduced, cogging is reduced and rotational unevenness is reduced.

Furthermore, in the electric motor according to the second claim, each permanent magnet can be assembled by a simple positioning operation of aligning it with the cylindrical inner circumferential surface of the rotor casing, and precise positioning operation is not required. This makes the work easier.

Furthermore, in the electric motor according to the third aspect, a fixing member is provided in the space created in the casing, and each permanent magnet is fixed by this, so complicated assembly work such as gluing is unnecessary, and therefore, the assembly work Improves sex.

Furthermore, in the electric motor according to the fourth aspect, by forming the outer circumferential surface of the salient poles of the stator into a specific shape, the distance between the outer circumferential surface of each salient pole of the stator and the inner circumferential surface of each permanent magnet can be reduced. It is possible to obtain an assembled state in which both ends in the circumferential direction are larger than the center side in the circumferential direction. In this way, the outer circumferential surface of the salient pole of the stator, which is easy to process, can be formed into the above-mentioned unique shape, thereby improving productivity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of an electric motor according to an embodiment of the present invention, FIG. 2 is a plan view of a fixing member in the electric motor, FIG. 3 is a front view of the fixing member, and FIG. FIGS. 5(a) to 5(f) are cross-sectional views of main parts of a fan device assembled to the fan rotor of a cross-flow fan installed in an indoor unit of a harmonizer, and each shows the rotational position of the rotor in the electric motor. Figures 6(a) to 6(f) are schematic diagrams showing the relationship between the rotational position of the rotor and the magnetic flux distribution generated in the stator in a conventional electric motor. , FIG. 7 is an assembled sectional view of main parts showing another embodiment of the present invention, FIG. 8 is a side view showing a stator of another embodiment, and FIG. 9 is a magnetic flux distribution in another embodiment. FIG. 10 is a schematic diagram showing magnetic flux distribution in a conventional case, and FIG. 11 is an assembled sectional view of a fan device installed in an indoor unit of a conventional air conditioner. 3... Rotor, 4... Casing, 8... Stator, 16.16°... Permanent magnet, 26... Fixed member, 30... Outer peripheral surface, P1 to P6... Salient pole, F...
Virtual cylindrical surface.

Claims (1)

[Claims] 1. A stator (8) having a plurality of salient poles (P1 to P6) extending radially; and a rotor (3) having a plurality of permanent magnets (16), and each of the permanent magnets (16) is configured such that the inner circumferential surfaces adjacent to each other in the circumferential direction have different poles, The distance between the virtual cylindrical surface (F) on which the outermost peripheral surface of each salient pole (P1 to P6) is located and the inner peripheral surface of each permanent magnet (16) on both ends in the circumferential direction is defined as the virtual Cylindrical surface (F) and each permanent magnet (
16) An electric motor characterized in that the distance is greater than the distance between the inner circumferential surface on the circumferential center side in 16). 2. In order to arrange each of the permanent magnets (16) along the cylindrical inner circumferential surface of the casing (4) of the rotor (3), the outer circumferential surface of each permanent magnet (16) is aligned with the cylindrical inner circumferential surface of the rotor (3). Each permanent magnet (16
2. The electric motor according to claim 1, wherein the inner circumferential surface of the motor is formed by an arcuate surface having a radius larger than the radius. 3. The permanent magnets (16) disposed along the cylindrical inner circumferential surface of the casing (4) come into contact with the inner circumferential surface on the circumferential end side to prevent the permanent magnets (16) from moving. The electric motor according to claim 2, characterized in that a fixing member (26) made of a non-magnetic material is provided in the casing (4) at a position outside the virtual cylindrical surface (F). 4. In order to arrange each of the above permanent magnets (16') along the cylindrical inner circumferential surface of the casing (4) of the rotor (3), the outer circumferential surface of each permanent magnet (16') is aligned with the inner circumferential surface of the cylindrical shape. The inner circumferential surface of each permanent magnet (16') is formed with a circular arc surface having approximately the same radius as the circumferential surface, and the inner circumferential surface of each permanent magnet (16') is formed with a radius smaller than the above radius.
In addition, the salient poles (P1 to P
The outer peripheral surface (30) extending in the circumferential direction of 6) is connected to the salient poles (P1~
The electric motor according to claim 1, wherein the distance between the permanent magnets (16') at both ends of the magnet P6) in the circumferential direction is larger than that at the center in the circumferential direction.