JP2002272073A - Rotating electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid interference between a rotor and a stator without degradation in power efficiency. SOLUTION: A rotating electric machine is constituted of a stator 1 and a rotor 2 concentrically placed inside the stator. The air gap 7 formed between the inner circumferential surface of the stator and the outer circumferential surface of the rotor is so established that the air gap is larger in the center than at both ends in the direction of the rotor shaft. Thus the rotor 2 is prevented from contacting the inner face of the stator 1 when the rotor vibrates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a rotating electric machine such as a synchronous motor.

[0002]

2. Description of the Related Art A synchronous motor in which a permanent magnet is embedded in a rotor and coils are concentratedly wound around a stator is disclosed in Japanese Patent Application Laid-Open No. 2000-69717.

[0003]

In such a synchronous motor, it is effective to reduce the air gap between the rotor and the stator as much as possible to improve the motor torque and output. However, the rotor vibrates due to rotation, and if the air gap is too small, the rotor rotating inside the stator comes into contact with the inner surface of the stator. This is particularly noticeable as the rotation axis of the rotor is longer and the rotation speed is higher.

Therefore, there is a limit in reducing the air gap between the rotor and the stator. In order to increase the motor torque and output while maintaining the allowable air gap, for example, measures such as increasing the size of the permanent magnet are used. It is necessary, and in this case, an increase in cost is unavoidable, and it is an obstacle to miniaturization.

An object of the present invention is to solve such a problem.

[0006]

According to a first aspect of the present invention, there is provided a rotating electric machine comprising a stator and a rotor concentrically disposed inside the stator, which is formed between an inner periphery of the stator and an outer periphery of the rotor. The air gap is set to be larger at the center in the rotor axis direction than at both ends.

In a second aspect based on the first aspect, the air gap is set so as to be maximum at a central portion in the axial direction of the rotor, minimum at both ends, and change continuously between them.

In a third aspect based on the first aspect, the air gap is set so as to be maximum at a central portion in the rotor axial direction, minimum at both ends, and change stepwise between them.

In a fourth aspect based on the first to third aspects, the air gap is formed by setting the inner diameter of the stator to a different inner diameter in the axial direction.

In a fifth aspect based on the first to third aspects, the air gap is formed by setting the outer diameter of the rotor to a different outer diameter in the axial direction.

In a sixth aspect based on the first to third aspects, the air gap is formed by setting the inner diameter of the stator and the outer diameter of the rotor to different inner and outer diameters in the axial direction.

In a seventh aspect based on the first to fourth aspects, the stator core constituting the stator is formed by laminating thin plates made of a magnetic material and having different stator inner diameters in the axial direction. Form an air gap.

According to an eighth aspect, in the first to fifth aspects, the rotor core constituting the rotor is a thin plate made of a magnetic material, and thin plates having different rotor outer diameters are laminated in the axial direction. Thus, the air gap is formed.

According to a ninth invention, in the first to third inventions, the stator is formed by a plurality of stator cores divided in a circumferential direction, and each stator core is formed by laminating axially the same thin plates made of a magnetic material. The air gap is formed by displacing the air gap in the radial direction.

According to a tenth aspect, in the sixth aspect, the stator is a stator core in which thin plates having different stator inner diameters are laminated in the axial direction, and the rotor is a rotor core in which thin plates having different rotor outer diameters are laminated in the axial direction. And the air gap is formed between the stator and the rotor.

According to an eleventh aspect, in the tenth aspect,
At least, the thin plate having a large stator inner diameter and the thin plate having a large rotor outer diameter are formed concentrically from the same steel plate, and the thin plate having a small stator inner diameter and the thin plate having a small rotor outer diameter are concentric from the same steel plate. Processed and formed.

[0017]

According to the first to eleventh aspects of the present invention, when the rotor vibrates due to centrifugal force during high-speed rotation,
The amplitude due to this vibration is maximum at the center in the rotor axial direction. However, to match the air gap between the outer periphery of the rotor and the inner surface of the stator to the amplitude of vibration,
By setting the maximum value at the center portion in the axial direction of the rotor and the smaller value toward both end portions, it is possible to avoid contact and interference between the rotor and the stator. In addition, since the air gap is small at both ends where the amplitude of vibration is small, compared to setting a uniform large air gap, the motor torque and output decrease depending on the air gap, and furthermore, Accordingly, it is possible to suppress an increase in the size of the permanent magnet required.

According to the second aspect, the air gap can be appropriately set in accordance with the vibration amplitude, and a reduction in motor torque and output can be suppressed to a minimum.

According to the third aspect of the present invention, the air gap is formed in a stepwise manner, thereby facilitating the manufacture of the air gap. As in the seventh and eighth aspects, when the stator and the rotor are formed by laminating thin plates. The number of types of the thin plate can be reduced, and the productivity is improved.

In the ninth aspect, the stator can be formed using the same thin plate, which is effective in suppressing an increase in production cost.

According to the eleventh aspect, there is little waste of material at the time of producing a thin plate, and it is economical.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a synchronous motor will be described with reference to the drawings.

FIGS. 1 and 2 show a first embodiment.

In FIG. 1, reference numeral 1 denotes a stator of a motor, and reference numeral 2 denotes a rotor coaxially disposed inside the stator.

The stator 1 comprises a stator core 4 made of a magnetic material and a coil 3. In this example, nine T-shaped stator pieces 4a of a T-shape consisting of teeth and a yoke are formed into a cylindrical shape. The coils 3a, 3b, 3c are concentratedly wound around each stator piece 4a as a set of three continuous stator pieces 4a, which are arranged in a circumferentially divided state along the inner circumference of the case 8. ing.

The rotor 2 has a rotor core 5 made of a magnetic material.
And permanent magnets 6 radially magnetized in six magnet insertion holes 5a provided on the same circumference of the rotor core 5 at equal intervals in the circumferential direction and parallel to the axis. The magnets 6 are respectively inserted and fixed.

An air gap 7 is formed between the stator 1 and the rotor 2.
Are arranged coaxially. The stator 1 is fixed to the inner surface of the case 8, and the rotor 2 is rotatably supported by the case 8 through bearings 10, 11 disposed at both ends of a shaft 9 penetrating the axis thereof.

The air gap 7 between the stator 1 and the rotor 2 has the largest gap near the middle A between the bearings 10 and 11 in the axial direction of the shaft 9 and approaches the bearings at both ends. The smaller the gap, the smaller the gap near both ends B.

For this reason, the inner diameter of the stator 1 is continuously changed so that the inner diameter at the center in the axial direction is maximum and the inner diameter at both ends is minimum.

The stator 1 and the rotor 2 have a laminated structure in which a plurality of thin plates 12 and 13 made of a magnetic material are stacked in the axial direction. By gradually changing the inner diameter and laminating these thin plates 12, the inner diameter is largest at the center and smaller at both ends.

It is to be noted that the thin plate 12 is prepared in such a manner that the inner diameter of the stator is continuously different from the end to the center of the stator 1 in half in the axial direction of the rotor, and the stator 1 is assembled by combining these two sets. Constitute.

Next, the operation will be described.

The rotor 2 rotates around the shaft 9 on the inner surface of the stator 1 by sequentially passing a current through the coils 3a, 3b, 3c in the circumferential direction. When the rotation speed of the rotor 2 increases, vibration may occur due to centrifugal force.
Shafts 9 supported by bearings 10 and 1
It bends around 1 as a fulcrum. The amplitude in the radial direction of the rotor 2 due to this vibration is greatest at the center of the rotor.

The air gap 7 between the outer periphery of the rotor 2 and the inner surface of the stator 1 is adjusted according to the amplitude of vibration.
, The contact between the rotor 2 and the stator 1 can be effectively avoided even during high-speed rotation. In addition, since the air gap 7 is reduced at both ends where the amplitude of vibration is small, the motor torque and output decrease depending on the air gap as compared with setting a large air gap uniformly. In addition, it is possible to minimize the increase in the size of the permanent magnet, which is required accordingly.

Next, a second embodiment is shown in FIG.

In this example, the air gap 7 is formed between the outer circumference of the rotor 2 and the stator core 4 having the same inner diameter without changing the inner diameter of the stator 1.
Is gradually shifted outward so that the air gap 7 becomes maximum at the center of the rotor.

The cylindrical stator core 4 is formed by sequentially arranging nine stator pieces 4a in the circumferential direction. If the stator pieces 4a are shifted outward in the radial direction, the inner diameter of the stator increases accordingly. Each stator piece 4a is formed by laminating the thin plates 12 in the axial direction. The thin plate 12 located at the central portion in the axial direction of the rotor 2 shifts most outward in the radial direction, and the shift amount decreases toward both ends. As a result, as shown in the figure, an air gap 7 is formed in which the gap is the largest at the center of the rotor and the gap continuously decreases toward both ends.

With such a configuration, all the thin plates 12 constituting the stator core 4 can be of the same shape, and the production cost can be reduced as compared with the case where members having different inner diameters are manufactured little by little. Also, after laminating the same shape, the inner diameter can be formed in a drum shape by cutting, but in this case, the electric resistance of the adjacent thin plate 12 on the inner peripheral processing surface becomes small, and the eddy current is reduced as much as possible. Although the purpose of the stacking type to suppress it is lost, such a problem can be avoided according to this example.

The outer peripheral surface of the stator 1 can be made the same diameter by cutting. In this case, the effect of the problem that the electric resistance between the adjacent thin plates is reduced is that the inner peripheral surface is machined. Therefore, as shown by the dotted line in the figure, the problem that the outer diameter of the stator 1 becomes larger at the center in the axial direction may be avoided by laminating the thin plates and cutting them to the same outer diameter.

FIG. 4 shows a third embodiment.

In this example, the stator core 4 is divided into three blocks in the axial direction instead of the air gap 7 in which the gap changes continuously as shown in FIGS. Is changed step by step for each block to increase productivity.

The thin plate 12 forming the stator 1 has two types, the inner diameter of the stator being large at the central portion A and the small at both end portions B, two of which are laminated at the center with a large inner diameter. Laminate small ones.

In this manner, although a portion where the gap is slightly extra than in the case where the gap of the air gap 7 is continuously changed in the axial direction appears, the stator cores 4 having various kinds of inner diameters are prepared. In comparison with this, for example, the number of punching dies in press working can be reduced, and the production cost can be reduced.

The stator core 4 is not divided into three blocks, but is divided into, for example, five and seven blocks according to the axial length of the motor, and the maximum stator inner diameter at the axial center is gradually shifted toward both ends. In this case, since the gap of the air gap 7 can be made more appropriate, it is possible to suppress a decrease in motor torque and output.

FIG. 5 shows a fourth embodiment.

In this example, not the stator 1 but the rotor 2
Is changed so that the air gap 7 between itself and the stator 1 is maximized at the central portion in the axial direction.

A plurality of thin plates 13 constituting the rotor core 5 having slightly different outer diameters of the rotor are prepared. These thin plates 13 are arranged such that the outer diameter of the thin plate 13 at the central portion in the axial direction of the rotor 2 becomes minimum and becomes maximum at both ends. To be laminated.

Also in this case, even if the central portion in the axial direction is swung so as to have the maximum amplitude with the rotation of the rotor 2, contact with the inner surface of the stator 1 is avoided because the outer diameter of the rotor at the central portion is small. Can be

FIG. 6 shows a fifth embodiment.

In this example, the rotor is divided into three blocks in the axial direction of the rotor, and the outer diameter of the rotor 2 is changed stepwise between the blocks to form an air gap 7 in which the gap at the axial center is increased. Thus, its productivity has been increased.

Two types of thin plates 13 are prepared so that the rotor outer diameter of the thin plate 13 constituting the rotor core 5 is small at a portion which becomes a block at the center in the rotor axis direction and large at blocks on both sides thereof. The air gap 7 is formed by laminating the blocks for each block so that the gap at the center in the rotor axial direction is maximized.

Although the block is divided into three blocks here, the block may be divided into five blocks and seven blocks, and the outer diameter of the rotor may be changed stepwise in each block.

FIGS. 7 and 8 show a sixth embodiment.

In this example, the inner diameter of the stator 1 and the rotor 2
By changing both the outer diameters of the first and second rotors, the air gap 7 formed between the stator 1 and the rotor 2 is formed so as to be maximum at the axial center.

The stator 1 and the rotor 2 are divided into three blocks in the axial direction of the rotor. The inner diameter of the stator 1 is large at the central portion A and small at both ends B, and the outer diameter of the rotor 2 is small at the central portion A. The air gap 7 is set to be larger at both ends B, and the air gap 7 is changed stepwise between the blocks so that the air gap 7 becomes maximum at the axial center.

The stator core 4 and the rotor core 5 are both formed by laminating thin plates 12 and 13. As shown in FIG. 8, the thin plates 12 and 13 serving as the laminated members are concentrically pressed from the same steel plate. When punching by
Generally, in order to ensure accuracy, at least a clearance of about 0.3 mm to 0.5 mm is required between the two.
It is considered that the air gap between the stator 1 and the rotor 2 is preferably about 0.3 mm to 0.5 mm when the gap does not change in the conventional axial direction. Therefore, when the air gap is less than this clearance, the punching accuracy of the laminated member is deteriorated, or each of the thin plates 12 and 13 is punched from a separate steel plate instead of the same steel plate. Waste increases.

Therefore, the thin plate 12a of the stator core 4 having a large inner diameter and the thin plate 13b of the rotor core 5 having a large outer diameter disposed at both ends thereof are punched out of the same steel plate. A thin plate 12b of the stator core 4 having a small inner diameter disposed at both ends in the direction;
Thin plate 1 of rotor core 5 having a small outer diameter arranged at the center
3a is punched from another identical steel plate.

By doing so, the stator thin plate 12 which is punched from a single steel plate by concentric pressing.
The rotor 13 and the rotor thin plate 13 can have a large clearance between each other, can increase the processing accuracy of each, and can eliminate waste of material.

As shown in the figure, if the axial width of the central portion A is set to be twice the width of both ends B, the necessary stator thin plate 12 and rotor thin plate 13 for one motor are required. Since the type and the number of sheets are the same, the waste of the material is minimized, and it is economical.

Although an example in which the present invention is applied to a synchronous motor has been described above, the present invention can be similarly applied to a generator.

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made within the scope of the technical idea of the present invention.

[Brief description of the drawings]

FIG. 1 is a front view of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view along the line XX.

FIG. 3 is a sectional view of a second embodiment.

FIG. 4 is a sectional view of a third embodiment.

FIG. 5 is a sectional view of a fourth embodiment.

FIG. 6 is a sectional view of a fifth embodiment.

FIG. 7 is a cross-sectional view of a sixth embodiment.

8 (a) and 8 (b) are explanatory diagrams showing the relationship between the stator core and the rotor core, and FIG. 8 (b) shows the relationship between the inner and outer diameters.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 2 Rotor 3 Coil 4 Stator core 5 Rotor core 6 Permanent magnet 7 Air gap 8 Case 9 Shaft 10,11 Bearing 12,13 Thin plate

Claims (11)

[Claims] 1. A rotating electric machine comprising a stator and a rotor concentrically disposed inside the stator, wherein an air gap formed between the inner periphery of the stator and the outer periphery of the rotor is formed at a central portion in the axial direction of the rotor. A rotating electric machine characterized by being set to be larger than both ends. 2. The rotating electric machine according to claim 1, wherein the air gap is set to be maximum at a central portion in the rotor axial direction, minimum at both ends, and change continuously between them. 3. The rotating electric machine according to claim 1, wherein the air gap is set to be maximum at a central portion in a rotor axial direction, minimum at both ends, and change stepwise between them. 4. The rotary electric machine according to claim 1, wherein the air gap is formed by setting the inner diameter of the stator to a different inner diameter in the axial direction. 5. The rotating electric machine according to claim 1, wherein the air gap is formed by setting the outer diameter of the rotor to a different outer diameter in the axial direction. 6. The rotating electric machine according to claim 1, wherein the air gap is formed by setting the inner diameter of the stator and the outer diameter of the rotor to be different from each other in the axial direction. 7. A stator core constituting the stator,
The rotating electric machine according to any one of claims 1 to 4, wherein the air gap is formed by laminating thin plates made of a magnetic material and having different stator inner diameters in the axial direction. 8. The air gap is formed by laminating a rotor core constituting the rotor, which is a thin plate made of a magnetic material and having different rotor outer diameters in the axial direction. The rotating electric machine according to any one of claims 5 and 6. 9. The air stator according to claim 1, wherein the stator is formed by a plurality of stator cores divided in a circumferential direction, and each stator core is formed by laminating thin plates of the same shape made of a magnetic material in the axial direction and displaced in the radial direction. Claim 1 to form a gap
3. The rotating electric machine according to any one of 3. 10. The stator comprises a stator core in which thin plates having different stator inner diameters are laminated in the axial direction, and the rotor comprises a rotor core in which thin plates having different rotor outer diameters are laminated in the axial direction. The rotating electric machine according to claim 6, wherein the air gap is formed between the rotating electric machines. 11. A thin plate having a large inner diameter of the stator and a thin plate having a large external diameter of the rotor are formed concentrically from the same steel plate, and a thin plate having a small internal diameter of the stator and a thin plate having a small external diameter of the rotor are formed. The rotating electric machine according to claim 10, wherein the rotating electric machine is formed concentrically from the same steel plate.