Motor rotor

Abstract

In conventional electric motor rotors, there was a possibility that the thickness of the FRP magnet holding member would be uneven. [Solution] The rotor R comprises a rotor shaft 1, a plurality of permanent magnets 2 arranged along the outer circumferential surface of the rotor shaft 2, end plates 3 that hold both axial end faces of the permanent magnets 2, and a cylindrical member 4 made of FRP that covers the outer circumferential side of the permanent magnets 2. The cylindrical member 4 has a structure in which a fiber tape 5 made of reinforcing fibers is spirally wound around the rotor shaft 1. The end plates 3 have a winding region 3A of the fiber tape 5 on the permanent magnet 2 side in the axial direction, and the starting portion 51, folded portion 2, and ending portion 53 of the fiber tape 5 are arranged within the winding region 3A. The thickness of the cylindrical member 4 is made uniform at least on the outer surface of the permanent magnets 2, ensuring sufficient strength of the cylindrical member 4 against high-speed rotation.

Description

Technical Field

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[0001] The present invention relates to a rotor used in an electric motor which is a motor or a generator.

Background Art

[0002] As a conventional rotor for an electric motor, for example, there is one described in Patent Document 1. Patent Document 1 describes a configuration in which a sleeve is provided on the outer periphery of a shaft body, a permanent magnet is disposed on the outer periphery of the sleeve, and further, a magnet holding member made of FRP having a cylindrical shape is provided on the outer peripheral side of the permanent magnet. The magnet holding member is formed by spirally winding a continuous fiber bundle of reinforcing fibers on the outer peripheral side of the permanent magnet to form a fiber layer having a predetermined thickness, impregnating the fiber layer with a resin, and subjecting it to a curing process to be made into FRP.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described conventional rotor for an electric motor, when the fiber bundle is spirally wound on the outer peripheral side of the permanent magnet, the fiber bundle is folded back on the outer peripheral surface of the permanent magnet, and the thickness of the end portion of the fiber layer, that is, the thickness of the end portion of the magnet holding member becomes locally small. When such a rotor is rotated at high speed, there is a possibility that the strength decreases at the end portion of the magnet holding member. On the other hand, if the thickness of the end portion of the magnet holding member is increased, the thickness of the fiber layer at the central portion becomes larger than necessary, and the air gap between the stator and the rotor also increases, which may lead to a decrease in the torque of the motor.

[0005] The present invention has been made in view of the conventional circumstances described above, and aims to provide an electric motor rotor in which a permanent magnet and a cylindrical member made of FRP covering the outer circumference of the permanent magnet are provided on the outer circumference of the rotor shaft, and the thickness of the cylindrical member is made uniform at least on the outer surface of the permanent magnet, thereby ensuring sufficient strength of the cylindrical member against high-speed rotation. [Means for solving the problem]

[0006] The rotor for an electric motor according to the present invention comprises a rotor shaft, a plurality of permanent magnets arranged along the outer circumferential surface of the rotor shaft, end plates that hold both end faces of the magnets in the axial direction, and a cylindrical member made of FRP that covers the outer circumferential side of the permanent magnets. The cylindrical member has a structure in which a fiber tape made of reinforced fibers is spirally wound around the rotor shaft. The rotor for an electric motor is characterized in that the end plates have a winding region of the fiber tape on the permanent magnet side in the width direction, and the starting portion, folded portion, and ending portion of the winding of the fiber tape are located within the winding region. [Effects of the Invention]

[0007] By adopting the above configuration, the rotor for an electric motor according to the present invention ensures that the thickness of the cylindrical member is uniform at least on the outer surface of the permanent magnet, thereby ensuring sufficient strength of the cylindrical member against high-speed rotation. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing a first embodiment of a rotor for an electric motor according to the present invention. [Figure 2] Figure 1 is a front view of the motor rotor as seen from the axial direction. [Figure 3] Figure 1 is a cross-sectional view showing the molding process of the cylindrical member of the electric motor rotor. [Figure 4] Figure 1 is a cross-sectional view showing the boundary between the end plate and the permanent magnet. [Figure 5]This is a cross-sectional view showing a second embodiment of the rotor for an electric motor according to the present invention. [Figure 6] This is a cross-sectional view showing a third embodiment of the rotor for an electric motor according to the present invention. [Figure 7] Figure 6 is a front view of the motor rotor as seen from the axial direction. [Modes for carrying out the invention]

[0009] <First Embodiment> The rotor R shown in Figures 1 and 2 comprises a rotor shaft 1, a plurality of permanent magnets 2 (four in the figures) arranged along the outer circumference of the rotor shaft 1, end plates 3, 3 that hold both axial ends of the permanent magnets 2, and a cylindrical member 4 made of FRP that covers the outer circumference of the permanent magnets 2. In other words, the rotor R, together with the stator S shown in Figure 2, constitutes an SPM motor.

[0010] The rotor shaft 1 in the illustrated example comprises a main body portion 1A at the axial center, which has the largest diameter, and multi-stage shaft portions 1B, 1B that are coaxially continuous with both end faces of the main body portion 1A, with permanent magnets 2 arranged on the outer circumferential surface of the main body portion 1A.

[0011] The end plate 3 is made of a disc-shaped member, with the shaft portion 1B of the rotor shaft 1 passing through its center, and has a winding region 3A of the fiber tape (5) of the cylindrical member 4 around its entire circumference on the side of the permanent magnet 2 in the axial direction (the axial center side of the large diameter portion 1A). In addition, the end plate 3 of this embodiment has a large diameter portion 3B around its entire circumference on the side of the shaft end of the permanent magnet 2 in the axial direction, which has a larger diameter than the diameter of the winding region 3A. In other words, the end plate 3 has a two-stage structure in which the large diameter portion 3B and the small diameter winding region 3A are arranged side by side in the width direction.

[0012] The cylindrical member 4 has a structure in which a continuous fiber tape 5 made of reinforcing fibers is spirally wound around the outer circumference of the permanent magnet 2. As shown in Figure 3, the cylindrical member 4 has a starting point 51 of the fiber tape 5 within the winding region 3A of one end plate 3, and the fiber tape 5 is spirally wound around the outer circumference of the permanent magnet 2. The cylindrical member 4 then has a folded-over portion 52 of the fiber tape 5 in the winding region 3A of the other end plate 3, and after repeating this winding process of the fiber tape 5 a suitable number of times, the cylindrical member 4 has an ending point 53 of the fiber tape 5 in the winding region 3A of either end plate 3.

[0013] More specifically, in the rotor R described above, the fiber tape 5 is wound in multiple layers around the outer circumference of the permanent magnet 2 and the winding region 3A of the end plate 3. During this process, a half-wrap is performed, where approximately half of the width of the upper fiber tape 5 overlaps the lower fiber tape 5. The spiral winding of the fiber tape 5 is then advanced axially, and the fiber tape 5 is folded back at the boundary between the winding region 3A and the large diameter section 3B of the end plate 3, resulting in one or more layers of winding. At this time, the side surface of the large diameter section 3B of the end plate 3 (the stepped surface with respect to the winding region 3A) functions as a wall.

[0014] As described above, the cylindrical member 4 made of FRP has the starting portion 51, the folded portion 52, and the ending portion 53 of the fiber tape 5 all located within the winding area 3A of the end plate 3. After winding the fiber tape 5, the cylindrical member 4 is impregnated with resin as needed and then cured to become FRP. Typically, this cylindrical member 4 is made of CFRP, which uses carbon fiber as the reinforcing fiber. The starting portion 52 and ending portion 52 of the fiber tape 5 are fixed in place by the curing process described above.

[0015] In the rotor R described above, by providing the folded portion 53 of the fiber tape 5 on the winding region 3A of the end plate 3, the thin portion at the end of the fiber tape 5, that is, the thin portion at the end of the cylindrical member 4, is outside the range of the permanent magnet 2. Therefore, at least the thickness of the cylindrical member 4 in the part that holds the permanent magnet 2 can be made uniform.

[0016] As a result, for the above-mentioned rotor R, even when the cylindrical member 4 covering the outer peripheral side of the permanent magnet 3 has the minimum thickness that can withstand the centrifugal force of the permanent magnet 4 during high-speed rotation, there is no folded-back portion on the permanent magnet 2 that is too thin to withstand the centrifugal force. Therefore, it is possible to achieve a structure that can sufficiently withstand the centrifugal force of the permanent magnet during high-speed rotation. Moreover, the above-mentioned rotor R can reduce the air gap between the permanent magnet 2 and the coil on the stator S side by making the thickness of the cylindrical member 4 uniform, and thus can contribute to an improvement in the torque of the motor.

[0017] In this way, for the above-mentioned rotor R for an electric motor, at least the thickness of the cylindrical member 4 on the outer surface of the permanent magnet 2 becomes uniform, and sufficient strength of the cylindrical member 4 against high-speed rotation can be ensured.

[0018] Also, since the above-mentioned rotor R has an end plate 3 with a large-diameter portion 3B having a diameter larger than the diameter of the winding region 3A, for the winding of the fiber tape 5 which is the forming process of the cylindrical member 4, the large-diameter portion 3B functions as the wall of the winding region 3A, making the winding operation easy and reliable. When the motor is configured, the large-diameter portion 3B will serve as a retaining means for the cylindrical member 4.

[0019] As a more preferable embodiment, the above-mentioned rotor R can adopt a configuration in which, as shown in FIG. 3, the axial length L of the winding region 3A is larger than the width W of the fiber tape 5.

[0020] As a result, for the above-mentioned rotor R, the area where the overlapping thickness of the folded-back portion 53 of the fiber tape 5 is non-uniform varies depending on the lap margin, and the condition where the area becomes the largest is when it is wound without a lap. At that time, if the width W of the fiber tape 5 is smaller than the axial length L of the winding region 3A of the end plate 3, the lap portion can be arranged in the winding region 3A. Therefore, at least the thickness of the fiber tape 5 protecting the permanent magnet 2 can be made uniform.

[0021] Furthermore, in a more preferred embodiment, the rotor R can be configured such that the outer surface of the winding region 3A of the end plate 3 and the outer surface of the permanent magnet 2 are located on the same plane, as shown in Figure 3.

[0022] As a result, the rotor R eliminates the step between the winding region 3A of the end plate 3 and the permanent magnet 2, preventing damage to the fiber tape 5 from the edge of the step, and ultimately contributing to further improvement of the strength of the cylindrical member 4.

[0023] Furthermore, in a more preferred embodiment, the rotor R can be configured such that, as shown in Figure 4, an adhesive tape 6 is attached to the outer circumference of the boundary between the winding region 3A and the permanent magnet 2, covering at least the entire circumference.

[0024] In the rotor R described above, a gap 7 may occur at the boundary between the end plate 3 and the permanent magnet 2. Therefore, in the rotor R described above, by filling the gap 7 with adhesive tape 6, the resin is prevented from flowing into the gap 7 during the curing process of the cylindrical member 4, and the resin contained in the fiber tape 5 is stably retained during molding. As a result, the strength reliability of the FRP cylindrical member 4 can be further enhanced.

[0025] <Second Embodiment> Figure 5 illustrates a second embodiment of the motor rotor according to the present invention. In the following embodiments, the same reference numerals are used for the same components as in the first embodiment, and detailed descriptions are omitted.

[0026] The motor rotor R shown in Figure 5 has the same basic configuration as the first embodiment, and the end plate 3 has a winding region 3A on the permanent magnet 2 side in the axial direction, and does not have a large diameter section (reference numeral 3B in Figure 1), and has the same diameter in the axial direction.

[0027] In this rotor R, for example, in the molding process of the cylindrical member 4, it is possible to perform the winding work of the fiber tape 5 using a ring-shaped jig 61 corresponding to the large diameter portion or a scribing tool, and it is also possible to make the cylindrical member 4 thinner and lighter. Furthermore, it is possible to attach the end plate 3 and a separate retaining ring after the cylindrical member 4 has been molded.

[0028] <Third Embodiment> The motor rotor R shown in Figures 6 and 7 comprises a rotor shaft 1, a rotor core 8 coaxially mounted on the rotor shaft 1, a plurality of permanent magnets 2 arranged circumferentially inside the rotor core 8, end plates 3, 3 that hold both axial end faces of the rotor core 8, and a cylindrical member 4 made of FRP that covers the outer circumference of the rotor core 8. In other words, the rotor R, together with a stator (not shown), constitutes an IPM motor.

[0029] The rotor core 8 is made up of numerous electromagnetic steel sheets laminated in the axial direction, and permanent magnets 2 are housed in multiple slots 9 formed in this laminate. In this rotor core 8, the width of the bridge portion B between its outer surface and the slots 9 is small, and there is a risk that the centrifugal force acting on the permanent magnets 2 will concentrate on the bridge portion B when the rotor R rotates at high speed. Therefore, the cylindrical member 4 receives the force acting on the bridge portion B, preventing damage to the bridge portion B.

[0030] Furthermore, the rotor R described above has a cylindrical member 4 in which a fiber tape (5) made of reinforcing fibers is spirally wound around the rotor shaft 1, and the end plate 3 has a winding region 3A of the fiber tape on the rotor core 8 side in the axial direction, and as explained in Figure 3, the starting portion (51), the folded portion (52), and the ending portion (53) of the fiber tape (5) are located within the winding region 3A.

[0031] As a result, the rotor RS described above, as in the first embodiment, has a uniform thickness of the cylindrical member 4 at least on the outer surface of the rotor core 8, ensuring sufficient strength of the cylindrical member 4 against high-speed rotation, and also reducing the air gap between the rotor core 8 and the stator, thereby improving the torque of the motor.

[0032] Furthermore, in the rotor R described above, the end plate 3 has a large-diameter portion 3B on the side of the permanent magnet 2 in the axial direction (opposite the rotor core 8 side). Similar to the first embodiment, the large-diameter portion 3B functions as a wall in the winding region 3A, making the winding work easy and reliable. When the motor is constructed, the large-diameter portion 3B also functions as a retainer for the cylindrical member 4.

[0033] Furthermore, since the rotor R described above has an axial length L of the winding region 3A that is greater than the width W of the fiber tape 5, similar to the first embodiment, the overlapping portion of the fiber tape (5) can be placed in the winding region 3A to make the thickness of the fiber tape (5) protecting the lower core 8 uniform.

[0034] Furthermore, the rotor R described above aligns the outer surface of the winding region 3A of the end plate 3 with the outer surface of the rotor core 8, eliminating any steps between the winding region 3A and the rotor core 8. This prevents damage to the fiber tape (5) due to the edges of the steps, and ultimately contributes to improving the strength of the cylindrical member 4.

[0035] Furthermore, by attaching adhesive tape 6 to the outer circumference of the boundary between the winding region 3A and the rotor core 8, the rotor R is configured such that, during the curing process of the cylindrical member 4, the gap between the winding region 3A and the rotor core 8 is filled, preventing the resin from flowing into the gap 7, while stably retaining the resin contained in the fiber tape (5) during molding. As a result, the strength reliability of the FRP cylindrical member 4 can be improved.

[0036] The rotor R for electric motors according to the present invention is not limited to the above embodiments, and its configuration can be modified as appropriate without departing from the spirit of the present invention. [Explanation of Symbols]

[0037] R Rotor 1. Rotor shaft 2 permanent magnets 3 End Plates 3A Winding area 3B Large diameter part 4. Cylindrical member 5 Fiber Tape 6 Adhesive tape 8 rotor cores 51 Starting point of winding 52 Folded section 53 End of winding

Claims

1. The system comprises a rotor shaft, a plurality of permanent magnets arranged along the outer circumferential surface of the rotor shaft, end plates that hold both axial end faces of the permanent magnets, and a cylindrical member made of FRP that covers the outer circumferential side of the permanent magnets. The cylindrical member has a structure in which a fiber tape made of reinforcing fibers is spirally wound around the rotor shaft. The rotor for an electric motor is characterized in that the end plate has a winding region for the fiber tape on the permanent magnet side in the axial direction, and the starting portion, folded portion, and ending portion of the fiber tape are located within the winding region.

2. The rotor comprises a rotor shaft, a rotor core coaxially mounted on the rotor shaft, a plurality of permanent magnets arranged circumferentially inside the rotor core, end plates that hold both axial end faces of the rotor core, and a cylindrical member made of FRP that covers the outer circumference of the rotor core. The cylindrical member has a structure in which a fiber tape made of reinforcing fibers is spirally wound around the rotor shaft. A rotor for an electric motor, characterized in that the end plate has a winding region for the fiber tape on the rotor core side in the axial direction, and the starting portion, folded portion, and ending portion of the fiber tape are located within the winding region.

3. The motor rotor according to claim 1 or 2, characterized in that the end plate has a large-diameter portion having a diameter larger than the diameter of the winding region on the axial end side of the permanent magnet in the axial direction.

4. The motor rotor according to claim 1 or 2, characterized in that the axial length of the winding region is greater than the width of the fiber tape.

5. The motor rotor according to claim 1, characterized in that the outer circumferential surface of the winding region of the end plate and the outer circumferential surface of the permanent magnet are located on the same plane.

6. The motor rotor according to claim 1, characterized in that adhesive tape is attached to the outer circumference of the boundary between the winding region and the permanent magnet, covering at least the entire circumference.

7. The motor rotor according to claim 2, characterized in that the outer circumferential surface of the winding region of the end plate and the outer circumferential surface of the rotor core are located on the same plane.

8. The rotor for an electric motor according to claim 2, characterized in that adhesive tape is attached to the outer circumference of the boundary between the winding region and the rotor core, covering at least the entire circumference.

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