JP2001298881A - Stator fixing structure of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stator fixing structure of a motor at a low cost which can prevent slipping only by inserting a stator core in a case, transfers heat of the stator smoothly to a case, and facilitates centering. SOLUTION: This fixing structure is provided with a stator core 24 in which an irregular engaging part 24A is formed on the outer peripheral surface, and a case 20 wherein a part 20A to be engaged which corresponds to the form of the engaging part 24A is formed on the inner peripheral surface and the engaging part 24A becomes the engaging state with the part 20A when the stator core 24 is inserted in the inside. When a rotor 10 installed in the stator core 24 rotates, a part of each protruding part 24a of the engaging part 24A comes into contact with the part 20A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stator mounting structure for an electric motor.

[0002]

2. Description of the Related Art An electric motor, i.e., a motor, has a stator fixed in a case, a rotor provided in the stator through a small gap, and when a current flows through a coil of the stator, the rotor is driven by electromagnetic force. Rotated.

[0003] Since the stator receives the reaction force accompanying the rotation of the rotor, the stator must always be firmly fixed in the case. Further, since the generated heat must be smoothly transmitted to the case, it is preferable that there is no gap between the stator and the case.

Therefore, conventionally, as a structure for mounting a stator to a case, the following three functions are mainly required in order for a motor to exhibit desired performance.

(A) The stator is prevented from idling in the case.

(B) The heat generated in the stator is transmitted to the case.

(C) The stator is centered and fixed to the case.

In order to satisfy this requirement, conventional fixing or mounting means for the stator include shrink fitting, keying, bolting and the like.

[0009]

However, when the motor is used under severe conditions, the stator mounting means by shrink fitting may not satisfy the requirements for idling prevention and the like.

That is, the stator is usually formed by laminating a high-permeability (magnetically conductive) material such as a thin silicon steel plate formed by punching, and the case is made of aluminum to reduce the weight. Therefore, shrink fitting is performed using the difference in the coefficient of thermal expansion between the two.

In this shrink fitting, if the stator is mounted with the case deformed, the above requirement (c) is not satisfied, the accuracy of the bearing part supporting the rotary shaft is reduced, and the motor does not operate smoothly. In some cases, not only is there a problem in productivity, but also there is a risk of malfunction due to the conditions in which the motor is used.

In the shrink fitting, the maximum temperature when using the motor is 10
Even at 0 ° C. or higher, the interference of the case is set so that the case and the stator are maintained in a tightly coupled state.However, for example, if the operation is performed under cold conditions where the minimum temperature is −30 ° C. or less, The motor may malfunction due to the contraction of the case.

[0013] In addition, when performing shrink fitting, not only heating equipment is required, but also considerable time and energy are required for heating, which is disadvantageous in terms of cost.

Since the outer diameter of the stator core needs to be smaller than the inner diameter of the case for the keying and the bolting, an air layer exists between the stator core and the case, and heat generated in the stator is transferred to the case. Although it has a problem in that it does not smoothly transmit and does not satisfy the requirement of the above (b), furthermore, if a portion serving as a back yoke of the stator is partially cut or removed, Since no key or bolt can be attached, the field may be weakened and the output torque may be reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is possible to prevent idling of the stator only by inserting the stator core into the case, and the heat of the stator is smoothly transmitted to the case. It is another object of the present invention to provide an electric motor stator mounting structure which has no problem in centering and is advantageous in cost.

[0016]

The object of the present invention is achieved by the following means.

(1) A stator core having an uneven engaging portion formed on an outer peripheral surface, and an engaged portion having a shape corresponding to the shape of the engaging portion are formed on an inner peripheral surface, and the stator core is provided inside. And a case in which the engaging portion is engaged with the engaged portion when inserted, and each of the protrusions of the engaging portion is rotated by rotating a rotor provided in the stator core. A stator mounting structure for an electric motor, wherein a part of each part is in contact with an engaged part.

(2) The stator mounting structure for an electric motor, wherein the engaging portion has a spline shape in which concave portions and convex portions extending in the axial direction of the outer peripheral surface of the stator core are alternately formed in the circumferential direction. .

(3) The engaging portion is characterized in that the outer diameter of the protruding tooth tip is between the inner diameter of the concave tooth bottom of the case and the inner diameter of the protruding tooth tip. Stator mounting structure for electric motor.

(4) In the engaging portion, the planar shape of each projection is an isosceles triangle, and the height of the isosceles triangle does not affect the outer diameter of the case. A stator mounting structure for a motor.

(5) The stator mounting structure for a motor, wherein the engaging portion has a tip angle of the isosceles triangle of less than 60 degrees.

[0022]

According to the first aspect of the present invention, an uneven engaging portion is formed on the outer peripheral surface of the stator core, and an engaged portion having a shape corresponding to the shape of the engaging portion is formed on the inner peripheral surface of the case. Since it is formed, assembly can be performed only by inserting the stator core into the case, no special equipment is required for assembling the motor, the working time or energy consumption is small, and the cost is extremely advantageous. Further, since a part of the engaging portion of the stator core is in contact with the engaged portion, the stator can be prevented from idling by the engagement between the engaging portion and the engaged portion, and the engaging portion and the engaged portion can be prevented. With this contact, the heat of the stator is smoothly transmitted to the case.

According to the second aspect of the present invention, since the projections and depressions of the engaging portion are formed in a spline shape extending in the axial direction, the stator core can be easily inserted into the case, and the assembling work of the motor becomes extremely easy. In addition, if the clearances at the tip and the bottom of the spline are strictly set so as not to cause a problem in motor performance, the centering of the stator and the case can be performed by the centering effect of the spline.

According to the third aspect of the present invention, if the outer diameter of the protruding tooth tip is set between the inner diameter of the concave tooth root of the case and the inner diameter of the protruding tooth tip, the stator core and the case can be operated even at a high temperature or a cold operation. The thermal effect on the engagement of the shaft is reduced.

According to the fourth aspect of the present invention, the planar shape of each projection is an isosceles triangle, which is reduced to such an extent that it does not affect the outer diameter of the case. The stator receiving the reaction exerts a self-centering function, and the centering of the stator and the case is automatically performed.

According to the fifth aspect of the present invention, the tip angle of the isosceles triangle is less than 60 degrees.
When torque is applied, one side of the tooth surfaces of the stator and the case come into surface contact with each other, but the contact area becomes larger than that of the perfectly circular stator and the case, and heat generated in the stator is easily transmitted to the case.

[0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described.

FIG. 1 is a longitudinal sectional view of an embodiment according to the present invention,
2 is a half sectional view taken along line 2-2 of FIG. 1, FIG. 3 is a schematic plan view showing only a stator core of the embodiment, and FIG. 4 is a schematic plan view showing only a cylindrical portion of a case of the embodiment. 5 is a plan view showing a state where the case and the stator of the embodiment are combined, and FIG. 6 is an enlarged view of a main part of FIG.

As shown in FIG. 1, the motor according to the present embodiment is a so-called inner-rotor type three-phase synchronous motor of a type in which a permanent magnet 11 is embedded in a rotor 10. The rotor 10 is provided with a small gap between the rotor 23 and the rotor 23.

The rotor 10 has a rotor core 12 formed by laminating a material having a high magnetic permeability (magnetic conductivity) such as a punched thin silicon steel plate. An output shaft is provided at the center of the rotor core 12. The output shaft 13 is rotatably supported by the case 20 via a bearing 14.

As shown in FIG. 2, the rotor core 12 has permanent magnets 1 in through holes formed at regular intervals in the circumferential direction.
1 is provided. The illustrated synchronous motor is a motor using six permanent magnets 11, but each permanent magnet 11
It is magnetized in its thickness direction, and N pole, S
The poles are arranged alternately.

On the other hand, the case 20 is formed of, for example, an aluminum alloy or the like, and as shown in FIG.
It is composed of a cylindrical part 21 and a cover 22.

The stator 23 mounted on the inner peripheral surface of the cylindrical portion 21 is, similarly to the rotor core 11, a stator core formed by laminating a plurality of plates made of a high magnetic permeability material such as a thin silicon steel plate. 24,
A stator coil 25 is embedded.

In this embodiment, as shown in FIGS. 2 and 3, the stator core 24 has an uneven engaging portion 24A in which isosceles triangles are continuously formed on the outer peripheral surface. As shown in FIGS. 2 and 4, an engaged portion 20 </ b> A having a shape corresponding to the shape of the engagement portion 24 </ b> A is formed on the inner peripheral surface, and only by inserting the stator core 24 into the case 20,
The engagement portion 24A and the engaged portion 20A are in an engagement relationship.

This will be described in more detail. The engaging portion 24A formed on the stator core 24 has a so-called spline shape in which convex portions 24a and concave portions 24b extending in the axial direction of the outer peripheral surface of the stator core 24 are alternately formed in the circumferential direction.

On the other hand, the engaged portion 20A formed on the case 20 also has the convex portion 20a and the concave portion 20b extending in the axial direction of the inner peripheral surface of the case 20 alternately formed in the circumferential direction.
The engaging portion 24A has a shape corresponding to the shape of the convex portion 24a and the concave portion 24b.

In this case, the engaging portion 24A is designed so that the outer diameter dimension d1 of the tooth tip of the convex portion 24a is between the inner diameter dimensions D1 and D2 of the convex tooth tip on the case 20 side and the concave tooth bottom. With this configuration, the operation of inserting the stator core 24 into the case 20 is extremely easy, and the engagement portion 24A and the engaged portion 20A are brought into the meshing relationship only by inserting the stator core 24 into the case 20. be able to.

The engaging portion 24A has an isosceles triangle shape in which each projection 24a is uniform over the entire circumference. The height H of the isosceles triangle affects the outer diameter D of the case 20. It is preferably small enough not to affect. Specifically, the height H is set to about 1% to 5% of the stator core 3 or 0.1%. It is preferable to set it to about several mm to several mm. If it becomes large enough to affect the outer diameter D of the case 20, it is equivalent to removing or removing the back yoke portion of the stator 23 like the above-mentioned key and bolt, the field is weakened, and the output torque is reduced. This is because it will decrease.

The isosceles triangle has a tip angle α
Is preferably less than 60 degrees.

More specifically, when the stator core 24 is inserted into the case 20, the state shown in FIG. 5 is obtained. The state of engagement between the engaging portion 24A and the engaged portion 20A is enlarged. When viewed, the state shown in FIG. 6 is obtained.

In particular, when the rotor 10 is rotating, the engagement portion 2 of the stator core 24 as shown in FIG.
One slope of the protrusion 24a in 4A contacts one slope of the protrusion 20a in the engaged portion 20A of the case 20, and the other slope of the engagement portion 24A and the other slope of the engaged portion 20A. Is in a state where a gap G exists.

First, the sum of the lengths of the slopes that are in contact with each other,
Considering the length of the portion where the stator core 24 and the case 20 are in contact with each other at the time of shrink fitting, if the triangle is an equilateral triangle, that is, if the tip angle α is 60 degrees, the side of the triangle abc shown in FIG. Since ab and side bc are equal in length, they have the same contact length. Therefore, the heat transfer between them is substantially the same.

However, when the tip angle α of the triangle is 60
If the angle is less than degree, the length of the side ab and the side bc in the triangle abc is side ab> side bc, and the length of the contact portion between the stator core 24 and the case 20 in the present embodiment is shrink-fit. It is larger than at the time and the difference in heat transfer is also very large, resulting in improved motor efficiency.

The engaging portion 24 of the stator core 24
The presence of the gap G between A and the engaged portion 20A of the case 20 has the advantage that the thermal effect caused by the difference in the coefficient of thermal expansion between the stator core 24 and the case 20 can be reduced even during high-temperature or cold operation. Will be created.

Next, the operation of the present embodiment will be described.

First, to assemble the motor according to the present embodiment, the stator core 24 is inserted into the case 20. This insertion is performed, for example, by gripping a stator coil 25 embedded in the stator core 24 with a robot or the like, so that the projection 20a of the case 20 and the projection 24a of the stator core 24 do not collide with the projection 24a of the stator core 24. The concave portion 20b of the projection 20 is fitted into the concave and convex portions.

Next, after inserting the pre-assembled rotor 10 into the stator core 24, the output shaft 13 is supported by the bearings 14, and the cover 22 of the case 20 is closed, whereby the assembly is completed.

As described above, the assembly of the stator 23 and the case 20 only requires the simple insertion of the stator core 24 into the case 20. This operation does not require a large facility, and does not require a large amount of time and energy. This is extremely advantageous.

When a supply voltage is applied to the rotor 10, the rotor 10 rotates. However, a reaction force against the rotation of the rotor 10 is received by the stator core 24.

In this stator core 24, the engaging portion 24A
Of the stator 2 is in contact with the engaged portion 20A.
3 can prevent idling. In addition, this contact state is larger than that at the time of shrink fitting, and the amount of heat transfer is extremely large, so that the heat dissipation is improved, and as a result, the motor efficiency is improved.

Further, since there is a gap G between the stator 23 and the case 20, even when the motor is operated at a high temperature of 100 ° C. or more, the minimum temperature is -30 ° C. or less. In the cold operation, the thermal effect on the engagement between the stator core 24 and the case 20 is reduced, and the above-mentioned various problems caused by the case 20 contracting in the cold operation do not occur.

In particular, in the present embodiment, since the convex portion 24a of the engaging portion 24A has an isosceles triangular shape, as shown in FIG.
If 4A moves in the direction of the arrow, the slope of the convex portion 24a of the engaging portion 24A moves along the slope of the engaged portion 20A of the case 20, thereby causing a centering effect, and
4 and the case 20 can be centered.

Further, the clearance between the spline tooth tip and the tooth bottom and the engaged portion 20A is set so strictly that there is no problem in the motor performance, for example, about 10 μm so that the deviation amount becomes small. You can do it,
In this way, centering between the stator 23 and the case 20 can be performed by the centering effect of the spline itself.

The motor is usually used in a horizontal position. In this case, the presence of the gap G does not cause any problem. That is, at the time of horizontal use, the stator core 24 is initially placed on the lower part of the case 20, but once the rotor 10 rotates, the stator core 24 is displaced to a predetermined position by the self-centering action, and the rotor 10 It rotates normally while maintaining a predetermined gap between.

The present invention is not limited to only the above-described embodiments, but can be variously modified and used within the scope of the claims. The engaging portion 24A and the engaged portion 20A of the embodiment have irregularities of an isosceles triangle, but the present invention is not limited to this, and depending on the shape, the alignment effect may not be expected much. Although there are some irregularities, irregularities such as trapezoids and gear teeth may be used.

The engaging portion 24A and the engaged portion 20A are
It is desirable to form it on the entire circumference of the stator 23 and the case 20, but it may be provided only on a part in the circumferential direction or only on a part in the axial direction.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment according to the present invention.

FIG. 2 is a half sectional view taken along line 2-2 of FIG.

FIG. 3 is a schematic plan view showing only a stator core of the embodiment.

FIG. 4 is a schematic plan view showing only a cylindrical portion of the case of the embodiment.

FIG. 5 is a plan view showing a state where the case and the stator of the embodiment are combined.

FIG. 6 is an enlarged view of a main part of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... rotor, 20 ... case, 20A ... engaged part, 20a ... convex part, 20b ... concave part, 23 ... stator, 24 ... stator core, 24A ... engaging part, 24a ... convex part, 24b ... concave part, D ... case The outer diameter of d1, the outer diameter of the protruding tooth tip, the inner diameter of the protruding tooth tip on the case D1, the inner diameter of the concave tooth bottom on the case D2, α: tip angle, G: clearance.

Claims (5)

[Claims] 1. A stator core having an uneven engaging portion formed on an outer peripheral surface, and an engaged portion having a shape corresponding to the shape of the engaging portion is formed on an inner peripheral surface, and the stator core is inserted inside. And a case in which the engagement portion is in mesh with the engaged portion. Each of the protrusions of the engagement portion is rotated by rotation of a rotor provided in the stator core. A part of each of which is in contact with an engaged portion. 2. The spline-shaped engagement portion in which a concave portion and a convex portion extending in an axial direction of an outer peripheral surface of the stator core are alternately formed in a circumferential direction.
3. The stator mounting structure for an electric motor according to claim 1. 3. The engaging portion, wherein the outer diameter of the protruding tooth tip is between the inner diameter of the concave tooth bottom of the case and the inner diameter of the protruding tooth tip. Item 3. The stator mounting structure for an electric motor according to item 1 or 2. 4. The engaging portion, wherein each of the projections has a planar shape of an isosceles triangle, and the height of the isosceles triangle is set to a size that does not affect the outer diameter of the case. The stator mounting structure for an electric motor according to any one of claims 1 to 3, wherein: 5. The stator mounting structure for an electric motor according to claim 4, wherein the engaging portion has a tip angle of the isosceles triangle smaller than 60 degrees.