Rotor member, rotor, and motor

Abstract

To provide a technique for suppressing a temperature rise of a rotor member in the rotor member for a motor.SOLUTION: A rotor member for a motor includes a rotor core part formed of ceramic and having a support part for supporting a magnet, and a shaft part connected to the rotor core part and formed of ceramic, and the rotor core part and the shaft part are formed of one ceramic member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rotor member, a rotor, and a motor. [Background technology]

[0002] BACKGROUND ART Rotor members for motors have been known for some time (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-40996 [Patent Document 2] International Publication No. 2018 / 147052 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even with the prior art such as Patent Documents 1 and 2, there is still room for improvement in the technology for suppressing temperature rise in rotor members for motors.

[0005] An object of the present invention is to provide a technique for suppressing a temperature rise in a rotor member for a motor. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following aspects.

[0007] (1) According to one aspect of the present invention, there is provided a rotor member for a motor, comprising: a rotor core portion formed of ceramic and having a support portion for supporting a magnet; and a shaft portion connected to the rotor core portion and formed of ceramic, wherein the rotor core portion and the shaft portion are formed from a single ceramic member.

[0008] According to this configuration, the rotor core and shaft of the rotor member are each made of ceramic. This reduces iron loss generated in the rotor member and suppresses an increase in mechanical loss due to friction, thereby suppressing heat generation due to iron loss and mechanical loss. Furthermore, because the rotor core and shaft are made of a single ceramic member, heat generated in the rotor core is easily transferred to the shaft. This makes it easier for heat generated in the rotor core to be released to the outside of the motor via the shaft, thereby suppressing temperature increases in the rotor member.

[0009] (2) In addition, in the rotor member of the above embodiment, the thermal expansion coefficient is 6.0 × 10 -6 / K or less, and the specific gravity is 5.0 g / cm 3 The following may be true. With this configuration, since the rotor member has a relatively small coefficient of thermal expansion, an increase in mechanical loss can be suppressed even when the temperature rises. This reduces output loss due to friction. Furthermore, since the specific gravity of the rotor member is relatively small, it can be rotated with a relatively small force. Therefore, the power required to rotate the rotor member at a predetermined rotation speed can be relatively small.

[0010] (3) In the rotor member of the above aspect, the rotor core portion may have a generally columnar shape, the shaft portion may be formed so as to protrude from an end face of the rotor core portion, and a connection portion between the rotor core portion and the shaft portion may be formed so as to have an R shape with an R of 0.2 mm or more. According to this configuration, the connection portion between the rotor core portion and the shaft portion formed so as to protrude from the end face of the rotor core portion is formed so as to have an R shape with an R of 0.2 mm or more. This makes it difficult for stress generated in the rotor member to concentrate at the connection portion, thereby suppressing damage to the rotor member.

[0011] (4) According to another aspect of the present invention, a rotor for a motor is provided. This rotor includes the rotor member described above, a magnet supported by the support portion, and a magnetic portion provided in the rotor core portion and formed of a metal or a ceramic having soft magnetic properties, the magnet forming a magnetic circuit passing through the magnetic portion. According to this configuration, the rotor core portion is provided with a magnetic portion through which the magnetic circuit formed by the magnet passes. The rotor member provided in the rotor core portion has relatively small iron loss and mechanical loss, and therefore is less likely to increase in temperature. This suppresses the temperature increase in the magnetic portion provided in the rotor core portion, thereby suppressing performance degradation of the magnetic portion.

[0012] (5) According to yet another aspect of the present invention, a motor is provided. The motor includes the rotor member described above, a magnet supported by the support, and a stator for the motor, disposed outside the rotor core and having windings for generating a magnetic field. With this configuration, the motor includes a rotor member made of ceramic, so iron loss and mechanical loss in the rotor are relatively small. This suppresses temperature rise in the rotor, thereby suppressing temperature rise in the entire motor.

[0013] The present invention can be realized in various forms, for example, in the form of an apparatus that uses a rotor member, a method for manufacturing a rotor member, a method for manufacturing a rotor or motor that includes a rotor member, or a computer program that causes a computer to execute the manufacturing of a rotor member. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of a motor including a rotor member according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of a rotor member according to the first embodiment. [Figure 3] FIG. 2 is a perspective view of a rotor according to the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view of the rotor of the first embodiment. [Figure 5] FIG. 2 is an enlarged view of part A in FIG. [Figure 6] 5A to 5C are diagrams illustrating evaluation results regarding the rotor member of the first embodiment. [Figure 7] FIG. 10 is a cross-sectional view of a rotor of a comparative example. [Figure 8] FIG. 10 is a cross-sectional view of a motor including a rotor member according to a second embodiment. [Figure 9] FIG. 10 is a perspective view of a rotor member according to a second embodiment. [Figure 10] FIG. 10 is a perspective view of a rotor according to a second embodiment. [Figure 11] FIG. 6 is a cross-sectional view of a rotor according to a second embodiment. [Figure 12] 10A and 10B are diagrams illustrating a magnetic circuit formed in a rotor according to a second embodiment. [Figure 13] 10A and 10B are diagrams illustrating evaluation results regarding the rotor member of the second embodiment. [Figure 14] FIG. 10 is a cross-sectional view of a rotor of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0015] First Embodiment 1 is a cross-sectional view of a motor including a rotor member according to a first embodiment. A rotor member 100 according to this embodiment is used in a motor 1 that outputs rotational torque when power is supplied. The motor 1 includes a rotor 10 having the rotor member 100, a stator 20, and a motor case 30. The rotor 10 is provided on a central axis C1 of the motor 1 so as to be rotatable about the central axis C1.

[0016] FIG. 2 is a perspective view of a rotor member of this embodiment. FIG. 3 is a perspective view of the rotor of this embodiment. FIG. 4 is a cross-sectional view of the rotor of this embodiment. The rotor 10 includes a rotor member 100 and a magnet 130. The rotor member 100 includes a rotor core portion 110 made of ceramic and having a support portion 111 for supporting the magnet 130, and a shaft portion 120 connected to the rotor core portion 110 and made of ceramic. In the rotor member 100 of this embodiment, the rotor core portion 110 and the shaft portion 120 are made of a single ceramic member. Whether the rotor member 100 is made of a single ceramic member can be confirmed by observing multiple cross sections of the rotor member 100. In the rotor member 100 of this embodiment, a connection portion P10 having an R-shaped outer surface P10a is provided at the boundary between the rotor core portion 110 and the shaft portion 120. Details of the connection portion P10 will be described later.

[0017] 2, the rotor core portion 110 has a substantially cylindrical shape. The support portions 111 are recessed portions formed on a side surface 112 of the rotor core portion 110. In this embodiment, four support portions 111 are formed on the side surface 112 of the rotor core portion 110, lined up along the circumferential direction of the rotor core portion 110.

[0018] The shaft portion 120 has two shaft portions 121, 122. Each of the two shaft portions 121, 122 is formed so as to protrude from each of two end faces 113, 114 of the rotor core portion 110, which has a substantially cylindrical shape (see FIG. 1). Each of the shaft portions 121, 122 has a substantially rod shape with its longitudinal direction aligned with the central axis C100 of the rotor member 100. The outer diameter of each of the shaft portions 121, 122 is smaller than the outer diameter of the rotor core portion 110. The end of each of the shaft portions 121, 122 opposite to the end connected to the rotor core portion 110 is exposed to the outside of the motor case 30, which will be described later.

[0019] The rotor member 100 of this embodiment has a thermal expansion coefficient of 6.0×10 -6 / K or less, and the specific gravity is 5.0 g / cm 3 The rotor member 100 of this embodiment has a thermal expansion coefficient of 3.3×10 -6 / K and specific gravity is 3.2 / cm 3The rotor member 100 is formed of silicon nitride (Si3N4), which has a relatively small thermal expansion coefficient. Silicon nitride has a relatively small thermal expansion coefficient, so its shape does not change significantly even when the temperature rises. This prevents friction with the bearings 310 and 320 (described later) from increasing even when the rotor member 100 rotates at high speed and the temperature rises. In other words, the rotor member 100 can prevent an increase in mechanical loss, particularly when rotating at high speed. The thermal expansion coefficient of the rotor member 100 is measured using a thermomechanical analyzer (TMA) (measurement sample size: 3 mm × 3 mm × 10 mm). Furthermore, because silicon nitride has a relatively small specific gravity, the rotor member 100 can be rotated with a relatively small force. This allows the power required to rotate the rotor member 100 at high speed to be relatively small. The specific gravity of the rotor member 100 is measured using the Archimedes method. The ceramic forming the rotor member 100 of this embodiment may be at least one of oxide-based ceramics such as alumina (Al2O3), silica (SiO2), titanium oxide (TiO2), zirconia (ZrO2), and magnesia (MgO); carbide-based ceramics such as silicon carbide (SiC), boron carbide (B4C), titanium carbide (TiC), and chromium carbide (CrC); and nitride-based ceramics such as aluminum nitride (AlN), titanium nitride (TiN), and sialon (SiAlON). The thermal expansion coefficient of the rotor member 100 is 3.0×10 -6 / K or more, and the specific gravity of the rotor member 100 is preferably 3.0 g / cm 3 The above is desirable.

[0020] FIG. 5 is an enlarged view of portion A in FIG. 1 and is a partially enlarged view of a cross section of the rotor member 100. In the rotor member 100 of this embodiment, the connection portion P10 between the rotor core portion 110 and the shaft portion 120 is formed to have an R shape with an R of 0.2 mm or more. Specifically, in the cross section of the rotor 10 shown in FIG. 5, the shape line of the end face 113 of the rotor core portion 110 and the shape line of the side surface 121a of the shaft portion 121 are smoothly connected by the shape line of the outer surface P10a of the connection portion P10. In this embodiment, the shape line of the outer surface P10a of the connection portion P10 has a concave shape that is recessed toward the inside of the rotor member 100 and has the same shape as the arc of an imaginary circle VC10 having a radius R10 of 0.2 mm or more and 1.0 mm or less. Therefore, the center C10 of the imaginary circle VC10 is located outside the cross section of the rotor member 100 in the cross section of FIG. 5. As described above, in the rotor member 100 of this embodiment, the connection portion between the rotor core portion 110 and the shaft portion 121 has a shape as shown in Fig. 5, so that stress generated in the rotor member 100 is less likely to concentrate at the connection portion P10. This makes it possible to suppress damage to the rotor member 100. Note that although Fig. 5 describes the connection portion P10 between the rotor core portion 110 and the shaft portion 121, the connection portion between the rotor core portion 110 and the shaft portion 122 has a similar shape. The magnitude of R of the R-shape at the connection portion P10 is calculated by averaging the values ​​at three cross sections.

[0021] The magnet 130 is supported by a support portion 111 of the rotor core portion 110. In this embodiment, the magnet 130 is supported by the rotor core portion 110 by being fitted into the support portion 111 of the rotor core portion 110, i.e., a recessed portion formed on the side surface 112 of the rotor core portion 110. In other words, the motor 1 of this embodiment is a so-called SPM motor in which the magnet 130 is mounted on the surface of the rotor core portion 110. The magnet 130 may be fixed to the recessed portion of the support portion 111 with an adhesive (resin), or may be fixed (for example, welded) directly to the rotor core portion 110 without using an adhesive.

[0022] The stator 20 has a stator core portion 210 and a winding 220 (see FIG. 1). The stator 20 is disposed outside the rotor core portion 110 and is fixed to the motor case 30, which will be described later, inside the motor case 30. The stator core portion 210 is formed to have a substantially cylindrical shape and has a plurality of protrusions 211 on the inside. The stator core portion 210 is formed by stacking a plurality of electromagnetic steel plates.

[0023] The windings 220 are conductor wires covered with an insulator, and are wound around each of the plurality of protrusions 211 of the stator core portion 210. When electricity supplied from outside the motor 1 flows through the windings 220, the windings 220 generate a magnetic field.

[0024] The motor case 30 is a hollow member that houses the rotor 10 and the stator 20. Two bearings 310, 320 are provided in the motor case 30. The bearings 310, 320 are provided on two opposing bracket portions 301, 302 of the motor case 30. One of the two shaft portions 121, 122, the shaft portion 121, is inserted through the bearing 310, and the other of the two shaft portions 121, 122, the shaft portion 122, is inserted through the bearing 320. As a result, the rotor 10 is rotatably supported by the motor case 30.

[0025] Next, an example of a manufacturing method for the rotor member 100 of this embodiment will be described. In the manufacturing method for the rotor member 100, first, predetermined amounts of ceramic particles and sintering aid are weighed as main raw materials. In this embodiment, columnar ceramic particles are added when weighing the ceramic particles. Next, the weighed materials are charged into a ball mill together with ethanol, and pulverized and mixed for a predetermined time to prepare a slurry. Next, the prepared slurry is extrusion-molded to form an extrusion-molded body having a generally columnar shape. Next, the extrusion-molded body is processed to form a portion that will become the shaft portion 120, a portion that will become the support portion 111, and the like, to prepare a processed molded body having the shape of the rotor member 100. In this embodiment, when preparing the processed molded body, the outer surface P10a of the connection portion P10 between the rotor core portion 110 and the shaft portion 120 is formed to have an R shape with an R of 0.2 mm or more. Finally, the processed molded body is fired by heating under predetermined conditions to produce the ceramic rotor member 100. The manufacturing method of the rotor member 100 shown here is an example, and the manufacturing method is not limited to this.

[0026] Next, an evaluation test of the rotor member in this embodiment will be described. In this evaluation test, 12 types of rotor members (hereinafter referred to as "samples") for use in SPM motors were produced, which differed in any of the rotor member material, thermal expansion coefficient, specific gravity, R-shape size, presence or absence of magnetic parts, or material, and each of the 12 samples was evaluated for "rotation efficiency," "rotatability," and "strength."

[0027] FIG. 6 is a diagram illustrating the evaluation results for the rotor member of this embodiment. Of the 12 types of samples used in this evaluation test, Samples 1 to 10 were manufactured by a method similar to the manufacturing method for the rotor member 100 of this embodiment. For each of Samples 1 to 10, the ceramic particle material used as the main raw material was selected so as to achieve the composition of the "material" shown in FIG. 6. Sample 11 was manufactured by stacking multiple electromagnetic steel sheets. Sample 12 was manufactured by extruding and processing epoxy resin. The volume ratio of Al2O3 to ZrO2 in Sample 4 and the volume ratio of Si3N4 to TiN in Sample 5 were both 7:3.

[0028] The "thermal expansion coefficient" and "specific gravity" shown in FIG. 6 indicate the thermal expansion coefficient and specific gravity of the "material" forming each of Samples 1 to 10 and Sample 12. The thermal expansion coefficient of the samples was measured by TMA using samples measuring 3 mm × 3 mm × 10 mm, similar to the method for measuring the thermal expansion coefficient of the rotor member 100 of this embodiment. The specific gravity of the samples was measured using the Archimedes method, similar to the method for measuring the specific gravity of the rotor member 100 of this embodiment. "R" shown in FIG. 6 indicates the R value of the R shape of the connection between the rotor core portion and the shaft portion for each of Samples 1 to 12. "R" shown in FIG. 6 indicates the processing value when each of Samples 1 to 12 was manufactured.

[0029] The "magnetic portion" shown in Fig. 6 indicates whether or not a magnetic portion that forms a magnetic circuit is provided in the rotor core portion for each of Samples 1 to 10. As shown in Fig. 6, each of Samples 1 to 10 does not have a magnetic portion.

[0030] FIG. 7 is a cross-sectional view of a rotor of a comparative example. In this evaluation test, the "rotation efficiency" and "rotatability" shown in FIG. 6 each show the results of a comparison with a rotor 90 of a comparative example. As shown in FIG. 7, the rotor 90 of the comparative example includes a rotor member 900 having a rotor core portion 91 and a shaft portion 92, and a plurality of magnets 93. In the rotor 90 of the comparative example, the rotor core portion 91 and the shaft portion 92 are formed from laminated electromagnetic steel plates, and the magnets 93 are mounted on a surface 912 of the rotor core portion 91.

[0031] The "rotational efficiency" shown in FIG. 6 indicates the ratio of output to input in a motor, i.e., the efficiency of the motor. The "rotational efficiency" was measured using the following method. First, the power required to maintain rotation at 3000 rpm was measured for a motor equipped with each of Samples 1 to 12 and a motor equipped with the comparative rotor 90 (hereinafter referred to as the "comparative motor"). Next, the ratio (ΔE) of the magnitude of the power measured for the motor equipped with each of Samples 1 to 12 to the power measured for the comparative motor was taken as the "rotational efficiency" and classified into the following symbols A, B, and C. A: 6%≦ΔE<11% (improvement of 6% to 10% compared to the comparison motor) B: ΔE>6% (improved by less than 6% compared to the comparison motor) C: ΔE was almost 0% (similar to the motor used in the comparison example)

[0032] The "rotational ability" shown in Figure 6 indicates the ease with which the rotor member rotates. The "rotational ability" was measured using the following method. First, the magnitude of the external force required to rotate samples 1 to 12, which did not have magnets, and the rotor member 900 of the comparative example at 10,000 rpm or more was measured. Next, the magnitude of the external force required to rotate the rotor member was determined as "rotational ability" and classified into the following symbols A, B, and C. A: Compared to the comparative motor, it can rotate with 95% or less of the external force. B: Compared to the comparison motor, it can rotate with 95% to 99% of the external force. C: Requires the same external force as the motor in the comparison example

[0033] The "strength" shown in Figure 6 was measured by the following method. First, the rotation speed of a motor equipped with each of Samples 1 to 12 was gradually increased, and the rotation speed at which the rotor member broke was measured. Next, the magnitude of the rotation speed was taken as "strength" and classified into the following symbols A, B, and C. A: The rotation speed at which the fracture occurred was 10,001 rpm or more. B: The rotation speed at which the fracture occurred was between 5001 rpm and 10,000 rpm. C: The rotation speed at which the fracture occurred was 5000 rpm or less

[0034] The "rotational efficiency" shown in Figure 6 confirmed that Samples 1 to 10, which are made of ceramic, exhibited superior performance to Sample 11, which is made of electromagnetic steel sheet. The electromagnetic steel sheet that forms Sample 11 has a larger thermal expansion coefficient than the ceramic that forms Samples 1 to 10. As a result, Sample 11 is prone to experiencing increased mechanical loss, such as friction between the bearing and shaft, as the temperature rises. On the other hand, Samples 1 to 10, which are made of ceramic, have a smaller thermal expansion coefficient, so they can suppress increases in mechanical loss even when the temperature rises. As a result, motors equipped with Samples 1 to 10 experience less output loss due to friction and can maintain a predetermined rotation speed with less power.

[0035] In addition, among Samples 1 to 10, the thermal expansion coefficient was 6.0 × 10 -6 / K or less, and Samples 5 to 10 have a thermal expansion coefficient of 6.0 × 10 -6 / K, it was confirmed that the sample exhibited superior performance in terms of "rotation efficiency" compared to samples 2 to 4. -6 / K or less, the increase in mechanical loss when the temperature rises can be further suppressed. As a result, the motors equipped with Sample 1 and Samples 5 to 10 can maintain a predetermined rotation speed with even less power.

[0036] In the "rotational performance" shown in Figure 6, it was confirmed that Samples 1 to 10, which are made of ceramic, exhibited superior performance to Sample 11, which is made of electromagnetic steel sheet. The electromagnetic steel sheet that forms Sample 11 has a higher specific gravity than the ceramic that forms Samples 1 to 10. Therefore, a larger external force is required to rotate Sample 11 at a predetermined rotation speed. On the other hand, the specific gravity of the ceramic that forms Samples 1 to 10 is relatively small, so a small external force is required to rotate Sample 11 at a predetermined rotation speed.

[0037] In addition, among samples 1 to 10, the specific gravity was 5.0 g / cm 3 Sample 2 and samples 4 to 10 have a specific gravity of 5.0 g / cm or less. 3 It was confirmed that it exhibited superior performance in terms of "rotation" compared to the larger Sample 1 and Sample 3. The specific gravity was 5.0 g / cm 3 Below this value, the external force required to rotate at a constant rotation speed becomes even smaller. As a result, the motors equipped with Sample 2 and Samples 4 to 10 can rotate at a predetermined rotation speed with even smaller external force.

[0038] In terms of "strength" shown in Figure 6, it was confirmed that Samples 1 to 10, which are made of ceramic, exhibited superior performance to Sample 12, which is made of epoxy resin. Furthermore, among Samples 1 to 10, Samples 9 and 10, which have an "R" of 0.2 mm or more, exhibited superior performance in terms of "strength" to Samples 1 to 8, which have an "R" of less than 0.2 mm. This is because, at the connection between the rotor core and shaft, when the R shape is 0.2 mm or more, stress generated in the rotor components is less likely to concentrate at the connection.

[0039] According to the rotor member 100 of this embodiment described above, the rotor core portion 110 and the shaft portion 120 included in the rotor member 100 are each formed from ceramic. This reduces iron loss generated in the rotor member 100 and suppresses an increase in mechanical loss due to friction, thereby suppressing heat generation in the rotor member 100 due to iron loss and mechanical loss. Furthermore, because the rotor core portion 110 and the shaft portion 120 are formed from a single ceramic member, heat generated in the rotor core portion 110 is easily transferred to the shaft portion 120. This makes it easier for heat generated in the rotor core portion 110 to be released to the outside of the motor 1 via the shaft portion 120, thereby suppressing a temperature rise in the rotor member 100.

[0040] Furthermore, according to the rotor member 100 of this embodiment, the thermal expansion coefficient is 6.0×10 -6 / K or less, and the specific gravity is 5.0 g / cm 3 As a result, the rotor member 100, which has a small thermal expansion coefficient, can suppress an increase in mechanical loss even when the temperature rises, thereby reducing output loss due to friction. Furthermore, because the specific gravity of the rotor member 100 is small, the rotor member 100 can be rotated with a relatively small force. Therefore, the power required to rotate the rotor member 100 at a predetermined rotation speed can be reduced.

[0041] Furthermore, according to the rotor member 100 of this embodiment, the outer surface P10a of the connection portion P10 between the rotor core portion 110 and the shaft portion 120 is formed to have an R shape with an R of 0.2 mm or more. This makes it difficult for stress generated in the rotor member 100 to concentrate on the connection portion P10, thereby preventing damage to the rotor member 100.

[0042] Furthermore, according to the motor 1 of this embodiment, the motor 1 includes the rotor member 100 made of ceramic, which reduces iron loss and mechanical loss in the rotor 10. This suppresses a temperature rise in the rotor 10, thereby suppressing a temperature rise in the entire motor 1.

[0043] Second Embodiment 8 is a cross-sectional view of a motor including a rotor member according to the second embodiment. The rotor member included in the rotor according to the second embodiment differs from the rotor member according to the first embodiment (FIG. 1) in that it includes a magnetic portion.

[0044] The rotor member 400 of this embodiment is used in a motor 2 that outputs rotational torque when power is supplied. The motor 2 includes a rotor 40 having the rotor member 400, a stator 20, and a motor case 30. The rotor 40 is provided on a central axis C2 of the motor 2 so as to be rotatable about the central axis C2.

[0045] FIG. 9 is a perspective view of a rotor member of this embodiment. FIG. 10 is a perspective view of the rotor of this embodiment. FIG. 11 is a cross-sectional view of the rotor of this embodiment. The rotor 40 includes a rotor member 400, a magnet 430, and a magnetic portion 440. The rotor member 400 includes a rotor core portion 410 formed of ceramic and having a support portion 411 for supporting the magnet 430, and a shaft portion 420 formed of ceramic and connected to the rotor core portion 410. In the rotor member 400 of this embodiment, similar to the rotor member 100 of the first embodiment, the rotor core portion 410 and the shaft portion 420 are formed of a single ceramic member. In the rotor member 400 of this embodiment, a connection portion P40 having an R-shaped outer surface P40a is provided at the boundary between the rotor core portion 410 and the shaft portion 420.

[0046] As shown in FIG. 9, the rotor core portion 410 has a substantially cylindrical shape. The support portion 411 of the rotor core portion 410 has an insertion hole with an opening formed in one end face 412 of two end faces 412, 413 of the substantially cylindrical rotor core portion 410. In this embodiment, the opening portion of the support portion 411 is formed to have an annular shape, and as shown in FIG. 10, a plurality of magnets 430 are provided in the support portion 411. The one end face 412 of the rotor core portion 410 has an opening portion of an insertion hole 414 into which a magnetic portion 440 is inserted. The opening portion of the insertion hole 414 is located inside the opening portion of the support portion 411. In this embodiment, a plurality of insertion holes 414 are formed so that one magnetic portion 440 is disposed across two adjacent magnets 430 among the plurality of magnets 430 supported by the support portion 411 (see FIG. 9).

[0047] The shaft portion 420 has two shaft portions 421, 422. The two shaft portions 421, 422 are formed so as to protrude from two end faces 412, 413 of the rotor core portion 410, which has a substantially cylindrical shape (see FIG. 8). Each of the shaft portions 421, 422 has a substantially rod shape with its longitudinal direction aligned with the central axis C400 of the rotor member 400. The outer diameter of each of the shaft portions 421, 422 is smaller than the outer diameter of the rotor core portion 410. The end of each of the shaft portions 421, 422 opposite to the end connected to the rotor core portion 410 is exposed to the outside of the motor case 30.

[0048] The rotor member 400 of this embodiment has a thermal expansion coefficient of 6.0×10 -6 / K or less, and the specific gravity is 5.0 g / cm 3The rotor member 400 is formed of a ceramic such as silicon nitride. The ceramic forming the rotor member 400 of this embodiment is at least one of oxide, carbide, and nitride. Specifically, the rotor member 400 is formed of at least one of oxide-based ceramics such as alumina (Al2O3), silica (SiO2), titanium oxide (TiO2), zirconia (ZrO2), and magnesia (MgO); carbide-based ceramics such as silicon carbide (SiC), boron carbide (B4C), titanium carbide (TiC), and chromium carbide (CrC); and nitride-based ceramics such as aluminum nitride (AlN), silicon nitride (Si3N4), titanium nitride (TiN), and sialon (SiAlON).

[0049] The magnets 430 are supported by support portions 411 of the rotor core portion 410. In this embodiment, the ten magnets 430 are supported by the rotor core portion 410 by being inserted into insertion holes formed in the support portions 411 of the rotor core portion 410. In other words, the motor 2 of this embodiment is a so-called IPM motor in which the magnets 430 are mounted inside the rotor core portion 410. The magnets 430 may be fixed to the insertion holes formed in the support portions 411 with an adhesive (resin), or may be fixed (for example, welded) directly to the rotor core portion 410 without using an adhesive.

[0050] The magnetic portion 440 is provided in the rotor core portion 410 and is made of a metal or a soft magnetic ceramic. Materials for forming the magnetic portion 440 include iron (Fe), cobalt (Co), nickel (Ni), nanocrystalline soft magnetic materials having nano-sized crystals in an amorphous alloy, electromagnetic steel sheets, and soft magnetic ceramics such as ferrite (Fe2O3). The magnetic portion 440 of this embodiment is made of electromagnetic steel sheets. Ten magnetic portions 440 are inserted into ten insertion holes 414 of the rotor core portion 410, respectively.

[0051] Fig. 12 is a diagram illustrating the magnetic circuit formed in the rotor of this embodiment. For convenience of illustration, Fig. 12 shows only the cross section of rotor 40 also shown in Fig. 11. In this embodiment, magnet 430 forms a magnetic circuit Mgc that passes through magnetic portion 440.

[0052] Next, an example of a manufacturing method for the rotor member 400 of this embodiment will be described. The manufacturing method for the rotor member 400 is a method similar to the manufacturing method for the rotor member 100 of the first embodiment. The manufacturing method for the rotor member 400 differs from the manufacturing method for the rotor member 100 in that a portion that becomes the shaft portion 420, a portion that becomes the support portion 411, an insertion hole 414 into which the magnetic portion 440 is inserted, and the like are processed in an extruded molded body to produce a processed molded body having the shape of the rotor member 400. In this embodiment, when producing the processed molded body, an outer surface P40a of a connection portion P40 between the rotor core portion 410 and the shaft portion 420 is formed to have an R shape with an R of 0.2 mm or more. Note that the manufacturing method for the rotor member 400 shown here is an example and is not limited to this manufacturing method.

[0053] Next, an evaluation test of the rotor member in this embodiment will be described. In this evaluation test, five types of samples of rotor members used in IPM motors were fabricated, and the "rotation efficiency," "rotatability," and "strength" of each of the five samples were evaluated in the same manner as in the evaluation test of the first embodiment.

[0054] 13 is a diagram illustrating the evaluation results for the rotor member of this embodiment. Each of Samples 13 to 17 used in this evaluation test was produced by a method similar to the manufacturing method for rotor member 400 of the second embodiment. For each of Samples 13 to 17, the material of the ceramic particles as the main raw material was selected so as to have the composition of the "material" shown in FIG.

[0055] The "thermal expansion coefficient" and "specific gravity" shown in FIG. 13 indicate the thermal expansion coefficient and specific gravity of the "material" forming each of Samples 13 to 17. The "thermal expansion coefficient" and "specific gravity" were measured using the same method as the evaluation method used in the first embodiment. "R" shown in FIG. 13 indicates the processing value of the R shape of the connection portion between the rotor core portion and the shaft portion for each of Samples 13 to 17 when they were manufactured. For all of Samples 13 to 17 shown in FIG. 13, "R" is 0.4 mm.

[0056] The "magnetic portion" shown in Figure 13 indicates the material forming the magnetic portion provided in the rotor core portion for each of Samples 13 to 17. Sample 13 has a magnetic portion formed from ferrite, and Sample 14 has a magnetic portion formed from a nanocrystalline soft magnetic material. Each of Samples 15 to 17 has a magnetic portion formed from an electromagnetic steel sheet.

[0057] Fig. 14 is a cross-sectional view of a rotor of a comparative example. In this evaluation test, the "rotation efficiency" and "rotatability" shown in Fig. 13 each show the results of a comparison with a rotor 95 of a comparative example. As shown in Fig. 14, the rotor 95 of the comparative example includes a rotor member 950 having a rotor core portion 96 and a shaft portion 97, and a plurality of magnets 98. In the rotor 95 of the comparative example, the rotor core portion 96 and the shaft portion 97 are formed from laminated electromagnetic steel plates, and the magnets 98 are inserted into support portions 961 of the rotor core portion 96.

[0058] As in the first embodiment, the "rotation efficiency" and "rotational performance" shown in Fig. 13 were evaluated using the same threshold values ​​as in the first embodiment, with the comparative rotor member 950 or an IPM motor including the comparative rotor member 950 as the evaluation standard. As a result, as shown in Fig. 13, it was confirmed that each of Samples 13 to 17 exhibited superior performance (evaluated as "A") in terms of both "rotational efficiency" and "rotational performance" compared to the comparative rotor member 950 or an IPM motor including the comparative rotor member 950.

[0059] As in the first embodiment, the "strength" shown in Fig. 13 was determined by gradually increasing the rotation speed of the motors equipped with each of Samples 13 to 17, measuring the rotation speed at which the rotor member broke, and using the same threshold value as in the first embodiment. As a result, as shown in Fig. 13, it was confirmed that each of Samples 13 to 17 also exhibited excellent performance (determined "A") in "strength."

[0060] According to the rotor member 400 of this embodiment described above, the rotor core portion 410 and the shaft portion 420 included in the rotor member 400 are each formed of ceramic. This reduces iron loss generated in the rotor member 400 and suppresses an increase in mechanical loss due to friction, thereby suppressing heat generation due to iron loss and mechanical loss. Furthermore, because the rotor core portion 410 and the shaft portion 420 are formed from a single ceramic member, heat generated in the rotor core portion 410 is easily transferred to the shaft portion 420. This makes it easier for heat generated in the rotor core portion 410 to be released to the outside of the motor via the shaft portion 420, thereby suppressing a temperature rise in the rotor member 400.

[0061] Furthermore, according to the rotor 40 of this embodiment, the rotor core 410 is provided with a magnetic section 440 through which a magnetic circuit formed by the magnets 430 passes. The rotor member 400 provided in the rotor core 410 has relatively small iron loss and mechanical loss, and therefore is less likely to increase in temperature. This also suppresses the temperature increase in the magnetic section 440 provided in the rotor core 410, making it possible to suppress performance degradation of the magnetic section 440 due to temperature changes.

[0062] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0063] [Variation 1] In the above-described embodiment, the rotor member has a thermal expansion coefficient of 6.0×10 -6 / K or less, and the specific gravity is 5.0 g / cm 3 However, the properties of the rotor member are not limited to these. -6 / K or greater, and the specific gravity is 5.0 g / cm 3 The thermal expansion coefficient may be 6.0 x 10 -6 / K or less, and the specific gravity is 5.0 g / cm 3 By satisfying the above, it is possible to reduce the electric power required to rotate the rotor member at a predetermined rotation speed.

[0064] [Variation 2] In the above-described embodiment, the connection portion between the rotor core portion and the shaft portion is formed to have an R-shape with an R of 0.2 mm or more. The shape of the connection portion between the rotor core portion and the shaft portion is not limited to this. R may also be approximately 0.1 mm. By forming the connection portion P10 in an R-shape, stress generated in the rotor member is less likely to concentrate on the connection portion, making it possible to suppress damage due to stress.

[0065] [Variation 3] In the above-described embodiment, the rotor member is formed from silicon nitride. However, the ceramic forming the rotor member is not limited to this. The ceramic forming the rotor member is preferably at least one of oxide, carbide, and nitride. When the ceramic forming the rotor member is at least one of oxide, carbide, and nitride, the rotor member becomes relatively lightweight and relatively strong. Therefore, not only is breakage during use suppressed, but the rotor member is also easily manufactured due to its excellent workability.

[0066] [Variation 4] In the second embodiment, the rotor 40 used in the motor 2, which is an IPM motor, includes the magnetic portion 440. The magnetic portion 440 may be omitted.

[0067] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0068] <Application example 1> A rotor member for a motor, comprising: a rotor core portion formed of ceramic and having a support portion for supporting the magnet; a shaft portion connected to the rotor core portion and made of ceramic, The rotor core and the shaft are formed from a single ceramic member. A rotor member characterized by: <Application example 2> The rotor member according to Application Example 1, The thermal expansion coefficient is 6.0 x 10 -6 / K or less, and the specific gravity is 5.0 g / cm 3 Below is the A rotor member characterized by: <Application example 3> The rotor member according to Application Example 1 or Application Example 2, The rotor core portion has a generally columnar shape, the shaft portion is formed so as to protrude from an end surface of the rotor core portion, The connection portion between the rotor core portion and the shaft portion is formed to have an R shape with an R of 0.2 mm or more. A rotor member characterized by: <Application Example 4> A rotor for a motor, comprising: The rotor member according to any one of Application Examples 1 to 3, a magnet supported by the support portion; a magnetic portion provided in the rotor core portion and formed of a metal or a ceramic having soft magnetic properties, The magnet forms a magnetic circuit passing through the magnetic portion. A rotor characterized by: <Application example 5> A motor, The rotor member according to any one of Application Examples 1 to 4, a magnet supported by the support portion; a stator for the motor, the stator being disposed outside the rotor core and having a winding for generating a magnetic field; A motor characterized by: [Explanation of symbols]

[0069] 1, 2...Motor 10,40...Rotor 20...Stator 100,400...Rotor parts 110,410...Rotor core part 111,411...Support part 120, 420...shaft section 130,430...Magnet 440...Magnetic part 220...winding Mgc...magnetic circuit

Claims

1. A rotor member for a motor, comprising: a rotor core portion formed of ceramic and having a support portion for supporting the magnet; a shaft portion connected to the rotor core portion and made of ceramic, The rotor core and the shaft are formed from a single ceramic member. A rotor member characterized by:

2. 2. The rotor member according to claim 1, The thermal expansion coefficient is 6.0 x 10 -6 / K or less, and the specific gravity is 5.0 g / cm 3 Below is the A rotor member characterized by:

3. 3. The rotor member according to claim 1 or 2, The rotor core portion has a generally columnar shape, the shaft portion is formed so as to protrude from an end surface of the rotor core portion, A connection portion between the rotor core portion and the shaft portion is formed to have an R shape with an R of 0.2 mm or more. A rotor member characterized by:

4. A rotor for a motor, comprising: The rotor member according to claim 1 or 2; a magnet supported by the support portion; a magnetic portion provided in the rotor core portion and formed of a metal or a ceramic having soft magnetic properties, The magnet forms a magnetic circuit passing through the magnetic portion. A rotor characterized by:

5. A motor, The rotor member according to claim 1 or 2; a magnet supported by the support portion; a stator for the motor, the stator being disposed outside the rotor core and having a winding for generating a magnetic field; A motor characterized by:

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