Rotor

Abstract

This rotor is for a rotating electrical machine and comprises: a cylindrical sleeve; a plurality of permanent magnets that are affixed to an inner peripheral surface of the cylindrical sleeve and arranged side-by-side in a circumferential direction; and a shaft disposed on the inner-diameter side of the permanent magnets.　Outer peripheral surfaces of all of the plurality of permanent magnets are located on the same circumference; a gap between the inner peripheral surfaces of the permanent magnets and an outer peripheral surface of the shaft varies between one permanent magnet and another permanent magnet; and the gap is filled with an adhesive. In this way, breakage of the sleeve on the outer-diameter side can be prevented, and peeling of the permanent magnets can be prevented.

Description

rotor

[0001] The present invention relates to a rotor, and more particularly to a rotor used in a surface magnet type rotating electric machine.

[0002] Surface magnet rotors, in which permanent magnets are attached to the surface, can efficiently utilize the magnetic properties of the permanent magnets, but they have the problem that the permanent magnets are not easily attached. Therefore, rotors that require particularly high speed rotation are reinforced by covering the permanent magnets with a cylindrical sleeve so that they can withstand centrifugal force.

[0003] Patent document 1 discloses a rotor in which a permanent magnet is sandwiched between a double-structured cylindrical sleeve, and describes that by forming a gap between the inner diameter sleeve and the permanent magnet that becomes larger toward the circumferential edge of the permanent magnet, it is possible to prevent the permanent magnet from cracking due to the inner diameter sleeve expanding when a shaft is pressed into the inner diameter sleeve.

[0004] Japanese Patent Application Publication No. 2016-096641

[0005] However, in the rotor described in Patent Document 1, permanent magnets are arranged on the outer peripheral surface of the inner diameter sleeve, and the permanent magnets are arranged based on the inner diameter sleeve. Therefore, if the permanent magnets have dimensional errors, a step will occur between the permanent magnets and the adjacent permanent magnets on the outer diameter side.

[0006] When the permanent magnets are subjected to a load in the outer diameter direction due to the rotation of the rotor, the steps between the permanent magnets dig into the outer diameter sleeve, causing stress to concentrate, which may damage the outer diameter sleeve that prevents the permanent magnets from peeling off.

[0007] The present invention was made in consideration of the problems associated with the prior art, and its purpose is to provide a rotor that prevents damage to the outer diameter sleeve that prevents the permanent magnets from peeling off.

[0008] As a result of extensive research into achieving the above-mentioned object, the inventors discovered that the above-mentioned object can be achieved by adhering the permanent magnets to the inner surface of a cylindrical sleeve on the outer diameter side that covers the permanent magnets so that the outer surfaces of all the permanent magnets are positioned on the same circumference, and by absorbing dimensional errors of the permanent magnets on the inner diameter side, thereby completing the present invention.

[0009] That is, the rotor of the present invention is a rotor for a rotating electric machine comprising a cylindrical sleeve, a plurality of permanent magnets aligned circumferentially and bonded to the inner peripheral surface of the cylindrical sleeve, and a shaft disposed radially inside the permanent magnets, wherein the outer peripheral surfaces of all of the permanent magnets are located on the same circumference, and the gaps between the inner peripheral surfaces of the permanent magnets and the outer peripheral surface of the shaft are different for each permanent magnet, and the gaps are filled with adhesive.

[0010] According to the present invention, the permanent magnets are bonded to the inner surface of the cylindrical sleeve so that the outer surfaces of all the permanent magnets are positioned on the same circumference, and dimensional errors of the permanent magnets are absorbed on the inner diameter side. This makes it possible to provide a rotor that prevents damage to the sleeve on the outer diameter side and prevents the permanent magnets from peeling off.

[0011] Fig. 1 is a cross-sectional view of an example of a rotor as seen from the axial direction; Fig. 2 is a diagram illustrating a conventional rotor in which steps occur on the outer diameter side surface between permanent magnets; Fig. 3 is a diagram illustrating a state in which dimensional errors of permanent magnets are absorbed between the permanent magnets and the shaft; Fig. 4 is a diagram illustrating a state in which a permanent magnet is tilted; Fig. 5 is a diagram illustrating a manufacturing procedure for a rotor of the present invention; Fig. 6 is a cross-sectional view of an example of a rotor in which spacers are arranged at equal intervals in the circumferential direction;

[0012] The rotor of the present invention will now be described in detail. As shown in Figure 1, the rotor of the present invention is a rotor for a surface permanent magnet (SPM) rotating electric machine, which includes a shaft 3 and a plurality of permanent magnets 2 arranged in a circumferential direction on the outer diameter side of the shaft, and further includes a cylindrical sleeve 1 made of CFRP arranged on the outer diameter side of the permanent magnets 2.

[0013] The cylindrical sleeve 1 resists the centrifugal force caused by the rotation of the rotor and supports the load acting on the permanent magnet in the radial direction, thereby preventing the permanent magnet 2 from peeling off.

[0014] In FIG. 1, the shaft 3 is shown as a regular polygon with the same number of angles as the permanent magnets when viewed from the axial direction, but it may also be circular.

[0015] In the surface magnet type rotating electrical machine, by arranging the permanent magnets 2 in a Halbach array, the magnetic field can be concentrated on one side, strengthening the magnetic force and improving the magnetic efficiency.

[0016] The Halbach array is an array in which radially magnetized permanent magnets 2a and circumferentially magnetized permanent magnets 2b are arranged in the circumferential direction, and is formed by connecting multiple permanent magnets with different magnetization directions.

[0017] Furthermore, since dimensional errors inevitably occur in each individual permanent magnet 2, when the permanent magnets 2 are arranged on the outer peripheral surface of the shaft 3 based on the inner diameter side of the shaft 3, steps due to the above-mentioned dimensional errors will occur on the outer diameter side surface between adjacent permanent magnets, as shown in the circled areas in Figure 2.

[0018] If the rotor rotates at high speed with this step occurring, the cylindrical sleeve 1 supporting the permanent magnet from the outer diameter side may be subjected to local stress from the step and may be damaged.

[0019] The rotor of the present invention overcomes the above-mentioned inconveniences caused by dimensional errors that inevitably occur in permanent magnets.

[0020] First, we will explain how to absorb radial dimensional errors. The rotor of the present invention is manufactured by applying a uniform thickness of adhesive to the inner peripheral surface of the cylindrical sleeve 1 on the outer diameter side so that the outer peripheral surfaces of all permanent magnets 2 are positioned on the same circumference, using the cylindrical sleeve 1 as a reference, and then press-fitting the shaft 3 into the inner diameter side of the permanent magnets.

[0021] Furthermore, if the permanent magnet 2 is manufactured so that its outer dimensions are within the allowable tolerance range and are not larger than the design dimensions, even if the permanent magnet 2 is pressed toward the outer diameter by pressing in the shaft 3, the permanent magnet will not expand beyond the design dimensions, and no steps will occur on the outer diameter side between adjacent permanent magnets.

[0022] Therefore, no local stress is applied to the cylindrical sleeve 1, which supports the load received by the permanent magnet 2 from the outer diameter direction, and the load received by the permanent magnet 2 is applied evenly to the inner surface of the cylindrical sleeve 1, thereby preventing damage to the cylindrical sleeve 1.

[0023] In the rotor of the present invention, the dimensional errors of the permanent magnets are absorbed between the permanent magnets 2 and the shaft 3, so that, as shown in FIG. 3, a gap is formed between the inner circumferential surface of the permanent magnet and the outer circumferential surface of the shaft, and the size of this gap differs between one permanent magnet and another.

[0024] In the rotor of the present invention, adhesive is applied to the outer peripheral surface of the shaft 3 and the inner peripheral surface of the permanent magnet 2, and potting, molding, gap filler, etc. are injected and hardened to fill the gaps, thereby fixing the permanent magnet 2 to the shaft 3. This further prevents damage to the cylindrical sleeve 1.

[0025] In other words, as the rotor rotates, the permanent magnet 2 receives a change in the magnetic field from the stator, which causes stress to be exerted on the permanent magnet 2 that tilts the permanent magnet in the direction in which the permanent magnet itself rotates, as shown by the arrow in Figure 4. This tilt of the permanent magnet 2 can also cause steps to form on the outer diameter side between adjacent permanent magnets.

[0026] By filling the gap between the permanent magnet and the shaft with adhesive and fixing the permanent magnet 2 to the shaft 3, tilting of the permanent magnet due to rotation of the rotor can be prevented, and damage to the cylindrical sleeve 1 can be prevented.

[0027] Furthermore, if there is a permanent magnet among the multiple permanent magnets that is exactly the designed size with no dimensional error, there will be no gap between this permanent magnet and the shaft, and therefore no adhesive layer will be present here, but this does not cause a problem because the permanent magnet abuts against the shaft and its tilt is regulated.

[0028] Next, a method for absorbing dimensional errors in the circumferential direction will be described. As described above, the rotor of the present invention has permanent magnets 2 arranged in a line in the circumferential direction on the inner circumferential surface of the cylindrical sleeve 1. As shown in Figure 5, the permanent magnets 2 are arranged sequentially in the circumferential direction and adjacent permanent magnets are bonded together with an adhesive layer 4 of uniform thickness to produce the rotor.

[0029] As described above, the permanent magnet 2 is made small so that its outer dimensions do not exceed the design dimensions within the allowable tolerance range. Therefore, dimensional errors in the permanent magnet 2 accumulate between the first and last permanent magnets attached, and as shown in Figure 5, the gap between the first and last permanent magnets attached becomes larger than the gaps between the other permanent magnets.

[0030] This large gap between the first and last permanent magnets adhered may be filled by making the adhesive layer thicker than other parts, or by inserting a spacer 5.

[0031] In this way, by placing adhesive layers 4 and spacers 5 between adjacent permanent magnets and filling the gaps between the adjacent permanent magnets, tilting of the permanent magnets as the rotor rotates can be prevented, and together with the adhesive layer between the inner surface of the permanent magnet and the outer surface of the shaft, damage to the cylindrical sleeve can be prevented.

[0032] When the large gap is filled with a thick adhesive layer, the thickness of the adhesive layer will be uniform except for that one location, and when a spacer is inserted, the rotor will only have a spacer in that one location.

[0033] In such a rotor in which the gap between the permanent magnets is significantly increased at only one location, torque fluctuations occur when the rotor rotates.

[0034] Therefore, before bonding the permanent magnets to the cylindrical sleeve, the outer dimensions of all the permanent magnets are measured to determine the size of the gap to be formed in advance, and then spacers 5 are inserted at the desired positions. As shown in Figure 6, by arranging the spacers 5 at equal intervals so as to divide the large gap into multiple locations, it is possible to suppress torque fluctuations during rotor rotation.

[0035] REFERENCE SIGNS LIST 1 Cylindrical sleeve 2a Permanent magnet 2b Permanent magnet 3 Shaft 4 Adhesive layer 5 Spacer

Claims

1. A rotor for a rotating electric machine comprising: a cylindrical sleeve; a plurality of permanent magnets aligned circumferentially and bonded to the inner peripheral surface of the cylindrical sleeve; and a shaft arranged on the inner diameter side of the permanent magnets, wherein the outer peripheral surfaces of all of the plurality of permanent magnets are positioned on the same circumference, and the gaps between the inner peripheral surfaces of the permanent magnets and the outer peripheral surface of the shaft are different between one permanent magnet and the other permanent magnets, and the gaps are filled with adhesive.

2. The rotor according to claim 1, wherein there is no gap between at least one of said plurality of permanent magnets and said shaft.

3. The rotor according to claim 1, wherein each of the plurality of permanent magnets has an adhesive layer between adjacent permanent magnets, and the thickness of each of the adhesive layers is uniform except for one location.

4. The rotor according to claim 1, wherein the plurality of permanent magnets have a spacer at at least one location between adjacent permanent magnets.

5. A rotor as claimed in claim 4, characterized in that it comprises a plurality of the spacers, the plurality of spacers being arranged at equal intervals.

6. The rotor according to claim 1, wherein said plurality of permanent magnets are in a Halbach array.

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