Motor

Abstract

This motor has a stator having a cylindrical shape and extending in an axial direction while being centered on a central axis, a rotor positioned radially inside with respect to the stator and configured to rotate while being centered on the central axis, and a casing accommodating the stator and the rotor. The casing has a first casing positioned radially outside with respect to the stator. The first casing has a first cylinder part which has a cylindrical shape and of which the inner circumferential surface is in contact with the outer circumferential surface of the stator, and a plurality of fins positioned on the outer circumferential surface of the first cylinder part and extending in the axial direction along the outer circumferential surface of the first cylinder part. At least one of the plurality of fins has a fin extension part protruding in the axial direction relative to an axial-direction end part of the first cylinder part.

Description

Motor

[0001] The present invention relates to a motor. This application claims priority based on Japanese Patent Application No. 2025-051213 filed on March 26, 2025, the content of which is incorporated herein by reference.

[0002] There is known a motor in which heat radiation fins are arranged on the outer peripheral surface of a motor casing. For example, Patent Document 1 discloses an in-vehicle motor having a structure in which an electromagnetic steel sheet laminate or the like is incorporated in a region surrounded by a first housing part and a second housing part, wherein a heat sink region having a fin shape for heat radiation is formed on the outer surface of the first housing part.

[0003] Japanese Unexamined Patent Publication No. 2022-133953

[0004] In the motor disclosed in Patent Document 1, the surface area of the casing is increased by the fins arranged on the outer peripheral surface of the casing. Thereby, heat dissipation performance via natural heat radiation can be improved. In such a configuration where heat is dissipated by fins, increasing the surface area of the fins can further improve the heat dissipation performance.

[0005] However, in order to increase the surface area of the fins, for example, extending the fins in the radial direction of the motor increases the overall outer diameter of the motor, making it difficult to reduce the size. Therefore, for a motor having fins, there is a demand for a motor configuration that can improve heat dissipation performance while suppressing an increase in size.

[0006] An object of the present invention is to improve heat dissipation performance while suppressing an increase in size in a motor having fins.

[0007] A motor according to an exemplary embodiment of the present invention comprises a cylindrical stator extending axially about a central axis, a rotor located radially inward from the stator and rotating about the central axis, and a casing housing the stator and the rotor. The casing has a first casing located radially outward from the stator. The first casing has a cylindrical first cylindrical portion whose inner circumferential surface contacts the outer circumferential surface of the stator, and a plurality of fins located on the outer circumferential surface of the first cylindrical portion and extending axially along the outer circumferential surface of the first cylindrical portion. At least one of the plurality of fins has a fin extension that protrudes axially beyond the axial end of the first cylindrical portion.

[0008] According to the present invention, in a motor having fins, it is possible to improve heat dissipation while suppressing an increase in size.

[0009] Figure 1 is a plan view of the motor according to Embodiment 1. Figure 2 is a cross-sectional view taken along line II-II in Figure 1, showing the schematic configuration of the motor according to Embodiment 1. Figure 3 is a plan view showing the motor with the cover removed. Figure 4 is a perspective view showing the schematic configuration of the first casing and the second casing. Figure 5 is an exploded view of Figure 4. Figure 6 is a partial cross-sectional view taken along line VI-VI in Figure 1, illustrating the positional relationship between the first cylindrical portion of the first casing, the second cylindrical portion of the second casing, and the fins. Figure 7 is a diagram corresponding to Figure 3 of a modified example of Embodiment 1. Figure 8 is a diagram corresponding to Figure 4 of a modified example of Embodiment 1.

[0010] The embodiments of the present invention will be described in detail below with reference to the drawings. Note that identical or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated. Furthermore, the dimensions of the components in each drawing do not necessarily accurately represent the actual dimensions of the components or their dimensional ratios.

[0011] In the following explanation, the direction parallel to the central axis P of the motor 100 will be referred to as the axial direction, the direction perpendicular to the central axis P will be referred to as the radial direction, and the direction along the arc centered on the central axis P will be referred to as the circumferential direction. Furthermore, in the axial direction, the direction in which the cover portion 7 is located relative to the first casing 5 will be referred to as the axial direction one, and the opposite direction will be referred to as the axial direction other. In each figure, the axial direction is indicated by A, the circumferential direction by C, the axial direction one by A1, and the axial direction other by A2.

[0012] Furthermore, in the following explanation, expressions such as “fixed,” “connected,” and “attached” include not only cases where components are directly fixed to each other, but also cases where they are fixed to each other via other components. In other words, in the following explanation, expressions such as “fixed” include both direct and indirect fixing of components to each other.

[0013] (Embodiment 1) (Motor) A motor 100 according to an exemplary embodiment 1 of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a plan view of the motor 100 according to embodiment 1. Figure 2 is a cross-sectional view taken along line II-II in Figure 1, and shows the schematic configuration of the motor 100 according to embodiment 1. Figure 3 is a plan view showing the motor 100 with the cover 7 removed.

[0014] As shown in Figures 1 to 3, the motor 100 includes a stator 2, a rotor 3, a casing 4, a power supply line 8, and a sensor unit 9.

[0015] As shown in Figure 2, the stator 2 is cylindrical in shape, extending in the axial direction A with respect to the central axis P. The stator 2 includes a stator core 21 and a stator coil 22.

[0016] The stator core 21 is cylindrical. The outer circumferential surface of the stator core 21 is in contact with the inner circumferential surface of the first casing 5 of the casing 4.

[0017] The stator coil 22 is wound around the stator core 21. The stator coil 22 has coil end portions 221 that protrude from one axial side A1 of the stator core 21 and the other axial side A2 of the stator core 21. In this embodiment, the coil end of the stator coil 22 is located on one axial side A1 of the stator core 21 and is connected to the power supply line 8. The illustration of the coil end is omitted.

[0018] The rotor 3 is positioned radially inward from the stator 2 and rotates about its central axis P. The stator 2 and rotor 3 can employ configurations similar to those of known stators and rotors. Therefore, a detailed description of the stator 2 and rotor 3 is omitted.

[0019] The casing 4 houses the stator 2 and the rotor 3. In this embodiment, the casing 4 has a first casing 5, a second casing 6, and a lid 7. The first casing 5, the second casing 6, and the lid 7 are arranged in order in the axial direction A1. Details of the casing 4 will be described later.

[0020] The power supply line 8 supplies power to the stator coil 22. In this embodiment, the power supply line 8 is positioned on one axial side A1 relative to the stator 2 and is electrically connected to the coil end of the stator coil 22. The power supply line 8 passes through the through hole 61a of the second cylindrical portion 61 of the second casing 6, and the end opposite to the coil end is brought out to the outside. The power supply line 8 is an example of the wiring section of the present invention.

[0021] The sensor unit 9 detects information related to the rotor 3. The configuration of the sensor unit 9 is not particularly limited. For example, the sensor unit 9 includes a rotation angle detection unit 91 that detects the rotation angle of the rotor 3, and a signal output unit 92 that outputs the detected rotation angle to the outside. For example, the rotation angle detection unit is a resolver.

[0022] In this embodiment, the rotation angle detection unit 91 is fixed to one axial side A1 of the partition plate portion 62 of the second casing 6. The signal output unit 92 is led out to the outside through a through hole 62a that penetrates the partition plate portion 62 in the thickness direction and a through hole 61a in the second cylindrical portion 61. The signal output unit 92 is an example of the wiring unit of the present invention.

[0023] (Casing) Next, the casing 4 will be described in detail with reference to Figures 2 to 6. Figure 4 is a perspective view showing the schematic configuration of the first casing 5 and the second casing 6. Figure 5 is an exploded view of Figure 4. Figure 6 is a partial cross-sectional view along the line VI-VI in Figure 1, illustrating the positional relationship between the first cylindrical portion 51 of the first casing 5, the second cylindrical portion 61 of the second casing 6, and the fin 52.

[0024] (First Casing) As shown in Figure 2, the first casing 5 is located radially outward with respect to the stator 2. The first casing 5 has a cylindrical first cylindrical portion 51 extending in the axial direction A, a plurality of fins 52, and a bottom portion 53 that covers the other axial side A2 of the first cylindrical portion 51. In this embodiment, the first cylindrical portion 51, the plurality of fins 52, and the bottom portion 53 are made of aluminum. In this embodiment, the first cylindrical portion 51, the plurality of fins 52, and the bottom portion 53 are integrally molded.

[0025] The first cylindrical portion 51 is cylindrical in shape and extends in the axial direction A, with its inner circumferential surface in contact with the outer circumferential surface of the stator 2.

[0026] As shown in Figures 5 and 6, the first cylindrical portion 51 has a flange portion 511 that extends radially outward at one end on the axial side A1. As shown in Figure 6, the second cylindrical portion 61 of the second casing 6 is located on the axial side A1 of the first cylindrical portion 51. The flange portion 511 functions as a mating surface between the first cylindrical portion 51 and the second cylindrical portion 61. The end face of the first cylindrical portion 51 on the axial side A1 is larger than that of the case without the flange portion 511. Therefore, the flange portion 511 allows the second cylindrical portion 61 to be easily positioned relative to the first cylindrical portion 51.

[0027] In this embodiment, the first cylindrical portion 51 has an inclined surface 511a connected to the flange portion 511 on the outer circumferential surface of the end on the axial side A1. That is, the first cylindrical portion 51 has a portion at the end on the axial side A1 that becomes thicker towards the axial side A1. This ensures rigidity at the end of the first cylindrical portion 51 on the second cylindrical portion 61 side, and suppresses deformation of the flange portion 511.

[0028] As shown in Figures 4 and 5, the multiple fins 52 are located on the outer circumferential surface of the first cylindrical portion 51 and extend in the axial direction A. The multiple fins 52 increase the surface area on the outer circumferential side of the first casing 5. This improves the heat dissipation performance of the first casing 5.

[0029] As shown in Figure 5, the plurality of fins 52 include a first fin 52a with an axial length equal to that of the first cylindrical portion 51, a second fin 52b that is longer in the axial direction A than the first cylindrical portion 51, and a third fin 52c that is shorter in the axial direction A than the first cylindrical portion 51. That is, a portion of the plurality of fins 52 has a fin extension 521 that protrudes axially beyond the axial end of the first cylindrical portion 51. The fin extension 521 increases the surface area of ​​the fin 52. Therefore, the heat dissipation performance of the first casing 5 can be improved.

[0030] In this embodiment, the second fin 52b, which is longer in the axial direction A than the first cylindrical portion 51, does not protrude in the other axial direction A2 than the first cylindrical portion 51, but protrudes in one axial direction A1 than the first cylindrical portion 51. That is, the fin extension 521 protrudes in one axial direction A1 relative to the first cylindrical portion 51. Therefore, as shown in Figure 4, the fin extension 521 faces the outer circumferential surface of the second cylindrical portion 61.

[0031] (Second Casing) As shown in Figures 2, 4, and 5, the second casing 6 is positioned on one axial side A1 relative to the first casing 5. That is, the second casing 6 is located on one axial side A1 relative to the stator 2 and rotor 3.

[0032] As shown in Figure 2, the second casing 6 has a second cylindrical portion 61 and a partition plate portion 62. The second cylindrical portion 61 is cylindrical in shape and extends in the axial direction A, and is located on one axial side A1 of the first cylindrical portion 51. As shown in Figure 6, the other axial side A2 of the second cylindrical portion 61 is in contact with the first cylindrical portion 51. The fin extension portion 521 of the first casing 5 is located radially outward with respect to the outer circumferential surface of the second cylindrical portion 61.

[0033] In this embodiment, the second cylindrical portion 61 is made of resin. As described above, the first cylindrical portion 51 and the plurality of fins 52 are made of aluminum. That is, the second cylindrical portion 61 is made of a material with a lower thermal conductivity than the first cylindrical portion 51 and the plurality of fins 52.

[0034] For example, in order to increase the surface area of ​​the casing, the first casing and the second casing can each be configured to have fins. In this configuration, heat is transferred to the fins of the second casing either through the second cylindrical portion or through the fins of the first casing. In order to transfer heat from the fins of the first casing to the fins of the second casing, it is necessary to bring the fins of the first casing and the fins of the second casing into contact.

[0035] In contrast, in the motor 100, the fins located radially outward from the second cylindrical portion 61 of the second casing 6 are fin extensions 521 that extend from the fins 52 of the first casing 5 toward the second cylindrical portion 61. Heat from the first cylindrical portion 51 is directly transferred to the fin extensions 521. Therefore, the heat dissipation performance of the casing 4 can be easily improved compared to a configuration in which the second casing has fins.

[0036] Furthermore, in the motor 100, the thermal conductivity of the fin extension 521 facing the outer circumferential surface of the second cylindrical portion 61 is higher than that of the second cylindrical portion 61. Therefore, the heat dissipation performance of the casing can be improved compared to a configuration in which the second casing has fins.

[0037] In this embodiment, as shown in Figure 6, the radial inner surface of the fin extension 521 is radially separated from the outer circumferential surface of the second cylindrical portion 61. This prevents the fin extension 521 of the first casing 5 from interfering with the second casing 6 when assembling the second casing 6 to the first casing 5 during the manufacturing of the motor 100.

[0038] Furthermore, if the fin extension 521 expands radially inward due to the transmitted heat, it is possible to prevent the fin extension 521 from coming into contact with the second cylindrical portion 61 located radially inward, thereby preventing stress from being generated in the second cylindrical portion 61.

[0039] As shown in Figures 4 and 5, the second cylindrical portion 61 has a through hole 61a that penetrates radially. As shown in Figure 3, the power supply line 8 and the signal output section 92 of the sensor unit 9 pass through the through hole 61a. Other members may or may not pass through the through hole.

[0040] In this embodiment, the second cylindrical portion 61 has a projection 611 that protrudes radially outward. The second cylindrical portion 61 also has four through holes 61a. Three of the four through holes 61a penetrate the second cylindrical portion 61 at the location of the projection 611. The power supply line 8 passes through the through holes 61a located at the projection 611. The second cylindrical portion may be configured without projections at the locations of the through holes. The through holes through which the power supply line passes do not have to be located at the location of the projection.

[0041] As shown in Figure 4, the fin extension 521 is not located in a position that overlaps radially with the through hole 61a. That is, the fin extension 521 is located in a position different from the through hole 61a in the circumferential direction when viewed in the axial direction A.

[0042] Therefore, the fin extension 521 does not interfere with the power supply line 8, the signal output unit 92, and other components that pass through the through hole 61a. In other words, a motor 100 is obtained in which the fin 52 is prevented from interfering with the power supply line 8, the signal output unit 92, and other components. Thus, a motor 100 with improved heat dissipation can be obtained without interfering with the through hole 61a.

[0043] As shown in Fig. 2, the partition plate portion 62 covers one axial side A1 of the second cylindrical portion 61. Accordingly, an accommodation space surrounded by the second cylindrical portion 61 and the partition plate portion 62 is formed in the casing 4. In the present embodiment, the feed line 8 arranged on the one axial side A1 with respect to the stator 2 and the signal output portion 92 of the sensor unit 9 are accommodated in the accommodation space. That is, the second casing 6 accommodates the wiring portion.

[0044] In the present embodiment, the central portion of the partition plate portion 62 is recessed toward the other axial side A2. Accordingly, an accommodation space surrounded by the partition plate portion 62 and the cover portion 7 covering the one axial side A1 of the second casing 6 is formed in the casing 4. As shown in Fig. 2 and Fig. 3, the rotation angle detection portion 91 of the sensor unit 9 is accommodated in the accommodation space on the one axial side A1 of the partition plate portion 62.

[0045] As shown in Fig. 2, the cover portion 7 covers the one axial side A1 of the second casing 6.

[0046] In the present embodiment, the fin extension portion 521 extends to the end portion on the one axial side A1 of the cover portion 7. That is, the axial length of the second fin 52b, which is longer in the axial direction A than the first cylindrical portion 51, is equal to the axial length of the casing 4.

[0047] Accordingly, the motor 100 in which the fins 52 do not protrude from the end portion on the one axial side A1 and the end portion on the other axial side A2 of the casing 4 is obtained. Therefore, the motor 100 with improved heat dissipation while suppressing an increase in size can be provided.

[0048] In the present embodiment, the first cylindrical portion 51 and the plurality of fins 52 of the first casing 5 are made of aluminum, and the second cylindrical portion 61 of the second casing 6 is made of resin.

[0049] That is, in the motor 100, a part of the casing 4 is made of resin. Resin has a lower density than aluminum. Therefore, the motor 100 that is lighter in weight than a motor in which the entire casing is made of aluminum can be obtained.

[0050] The first casing 5, the second casing 6, and the lid 7 each have fixing protrusions 41 on their outer circumference that project radially outward from the same position in the circumferential direction. As shown in Figure 2, the fixing protrusions 41 have fastening holes 42 that penetrate in the axial direction A. A fastening member F is inserted into the fastening hole 42. The first casing 5, the second casing 6, and the lid 7 are fixed to each other by the fastening member F. The fixing protrusions 41 correspond to the protrusions of the present invention.

[0051] The fixing projection 41 of the first casing 5 is located on one axial side A1 of the first cylindrical portion 51. Therefore, in the first cylindrical portion 51, the radial position of the outer circumferential surface located on the other axial side A2 relative to the fixing projection 41 is the same as the radial position of the outer circumferential surface in other parts of the first cylindrical portion 51. In this embodiment, in the first cylindrical portion 51, the third fin 52c is located on the other axial side A2 relative to the fixing projection 41. The length of the third fin 52c in the axial direction A is shorter than the length of the first cylindrical portion 51.

[0052] In other words, in this embodiment, the first casing 5, the second casing 6, and the lid 7 each have fixing protrusions 41 that project radially outward. The fixing protrusions 41 have fastening holes 42 into which fastening members F are inserted axially. The first casing 5, the second casing 6, and the lid 7 are fixed to each other by the fastening members F inserted into the fastening holes 42 of the fixing protrusions 41. The plurality of fins 52 include a third fin 52c located on the other axial side A2 relative to the fixing protrusions 41.

[0053] This provides a configuration in which the fins 52 are positioned in the circumferential direction of the first cylindrical portion 51, overlapping with the fixing projection 41 when viewed in the axial direction A, without interfering with the fixing projection 41. This allows for a larger surface area of ​​the first casing 5. Therefore, in a motor with fins, heat dissipation can be improved while suppressing an increase in size.

[0054] The exemplary motor 100 according to this embodiment described above is a motor having a cylindrical stator 2 extending in the axial direction A about a central axis P, a rotor 3 located radially inward from the stator 2 and rotating about the central axis P, and a casing 4 that houses the stator 2 and the rotor 3. The casing 4 has a first casing 5 located radially outward from the stator 2. The first casing 5 has a cylindrical first cylindrical portion 51 whose inner circumferential surface contacts the outer circumferential surface of the stator 2, and a plurality of fins 52 located on the outer circumferential surface of the first cylindrical portion 51 and extending in the axial direction A along the outer circumferential surface of the first cylindrical portion 51. At least one of the plurality of fins 52 has a fin extension portion 521 that protrudes in the axial direction A beyond the axial A end of the first cylindrical portion 51.

[0055] The first cylindrical portion 51 of the first casing 5, which is in contact with the outer circumferential surface of the stator 2, dissipates heat generated from the stator 2 to the outside. By having fins 52 on the outer circumferential surface of the first cylindrical portion 51 of the first casing 5, the surface area of ​​the outer circumferential side of the first casing 5 is increased. Therefore, the amount of heat dissipated by the first casing 5 can be increased in the motor 100.

[0056] In the above configuration, at least one of the multiple fins 52 protrudes in the axial direction A beyond the axial end A of the first cylindrical portion 51. Therefore, in the motor 100, the surface area of ​​the first casing 5 is larger than, for example, a motor in which the axial length of the fins is the same as that of the first cylindrical portion, thus improving the heat dissipation of the casing 4. This makes it possible to improve the heat dissipation of the motor 100 without increasing the outer diameter of the motor 100. Thus, in a motor with fins, it is possible to improve heat dissipation while suppressing an increase in size.

[0057] In this embodiment, the casing 4 has a second casing 6 positioned on one axial side A1 relative to the first casing 5. The second casing 6 has a cylindrical second cylindrical portion 61 located on one axial side of the first cylindrical portion 51. The fin extension 521 protrudes further axially A1 than the first cylindrical portion 51 and faces the outer circumferential surface of the second cylindrical portion 61.

[0058] In the motor 100, the first cylindrical portion 51 of the first casing 5 is in contact with the stator 2, while the second cylindrical portion 61 of the second casing 6 is not in contact with the stator 2. In this configuration, the heat from the stator 2 is directly transferred to the first cylindrical portion 51, which is in contact with the stator 2, but not directly transferred to the second cylindrical portion 61, which is not in contact with the stator 2. Therefore, increasing the surface area of ​​the first casing 5 is more effective in improving heat dissipation efficiency than increasing the surface area of ​​the second casing.

[0059] In the above configuration, the fins facing the outer circumferential surface of the second cylindrical portion 61 of the second casing 6 are part of the fins 52 of the first casing 5. In other words, in the above configuration, the fins 52 facing the outer circumferential surface of the second cylindrical portion 61 are not present in the second casing 6, but in the first casing 5. This makes it easy to increase the surface area of ​​the first casing 5. Therefore, the heat dissipation of the motor 100 can be improved without increasing the outer diameter of the motor 100. Thus, in a motor with fins, heat dissipation can be improved while suppressing an increase in size.

[0060] (Modified Version of Embodiment 1) Next, a modified version of the motor 101 according to Embodiment 1 will be described with reference to Figures 7 and 8. In this modified version, the configuration of the second cylindrical portion 161 of the second casing 106 in the casing 104 of the motor 101 differs from the configuration of the second cylindrical portion 61 of the second casing 6 of the motor 100 according to Embodiment 1. In the following, the same reference numerals are used for components identical to those in Embodiment 1, and their descriptions are omitted. Components that differ from those in Embodiment 1 will be described.

[0061] Figure 7 is a plan view showing the motor 101 with the cover 7 removed according to this modified example. Figure 8 is a perspective view showing the schematic configuration of the first casing 5 and the second casing 106 of the motor 101.

[0062] The casing 104 of the motor 101 according to this modified example has a first casing 5, a second casing 106, and a lid 7. The second casing 106 has a second cylindrical portion 161 and a partition plate portion 62.

[0063] As shown in Figure 8, the second cylindrical portion 161 is cylindrical in shape and extends in the axial direction A, and is located on one axial side A1 of the first cylindrical portion 51. The second cylindrical portion 161 is made of resin. The fin extension portion 521 of the first casing 5 faces the outer circumferential surface of the second cylindrical portion 161.

[0064] The partition plate portion 62 covers one axial side A1 of the second cylindrical portion 161. The housing space enclosed by the second cylindrical portion 161 and the partition plate portion 62 houses the power supply line 8, which is positioned axially on one side A1 relative to the stator 2, and the signal output section 92 of the sensor unit 9. The power supply line 8 and the signal output section 92 are examples of the wiring section of the present invention. In other words, the second casing 106 houses the wiring section.

[0065] As shown in Figures 7 and 8, the second cylindrical portion 161 has a connecting terminal portion 163 that penetrates radially. The connecting terminal portion 163 has terminals on its radially inner and radially outer sides, to which wiring can be electrically connected. The radially inner terminal of the connecting terminal portion 163 is connected to the power supply line 8 and the signal output unit 92 housed in the second casing 106. The radially outer terminal of the connecting terminal portion 163 is connected to an external device that is electrically connected to the power supply line 8 and the signal output unit 92. In this embodiment, the connecting terminal portion 163 protrudes radially outward from the second cylindrical portion 161. However, the connecting terminal portion may be configured not to protrude radially outward from the second cylindrical portion.

[0066] The connection terminal portion 163 can be integrally embedded in the second cylindrical portion 161, which is made of resin, by insert molding when forming the second cylindrical portion 161. This eliminates the need to attach the connection terminal portion 163 during the manufacturing of the motor 101, thereby simplifying the motor manufacturing process. Furthermore, since the second cylindrical portion 161 and the connection terminal portion 163 can be integrated by insert molding, the airtightness of the casing 4 can be improved.

[0067] In this modified example, the second cylindrical portion 161 has two connection terminal portions 163. The radially inner terminals of the two connection terminal portions 163 are connected to the power supply line 8 and the signal output portion 92, respectively.

[0068] As shown in Figure 8, the fin extension 521 is not located in a position that overlaps radially with the connection terminal 163. In other words, the fin extension 521 is located at a different position from the connection terminal 163 when viewed in the axial direction A.

[0069] In other words, the motor 101 according to this modified example has a wiring section arranged in the axial direction A1 with respect to the stator 2. The second casing 106 houses the wiring section. The second cylindrical section 161 of the second casing 106 has a radially penetrating connection terminal section 163 to which the wiring section is electrically connected and to which an external device is electrically connected. The fin extension section 521 is located at a different position from the connection terminal section 163 when viewed in the axial direction A.

[0070] This results in a configuration in which the fin extension 521 does not overlap radially with the connection terminal portion 163. In other words, a motor 101 is obtained in which the fin 52 is prevented from interfering with the connection terminal portion 163 and external devices electrically connected to the connection terminal portion 163. Therefore, in a motor 101 having a connection terminal portion 163, heat dissipation can be improved without interfering with the connection terminal portion 163 and the external devices.

[0071] (Other Embodiments) Although embodiments of the present invention have been described above, the embodiments described above are merely examples for carrying out the present invention. Therefore, the invention is not limited to the embodiments described above, and it is possible to carry out the invention by appropriately modifying the embodiments described above without departing from the spirit of the invention.

[0072] In each of the above embodiments, the coil ends of the stator coil 22 protrude from one axial direction A1 of the stator core 21. However, the coil ends of the stator coil may also protrude from the other axial direction of the stator core. In this case, the power supply line may be arranged in the other axial direction relative to the stator.

[0073] In the above embodiment 1, the casing 4 includes a first casing 5, a second casing 6, and a lid 7. However, the casing does not have to include a second casing. That is, one axial side of the first casing may be covered by a bottomed cylindrical lid. In this case, the fin extension may face the outer circumferential surface of the lid. Also, other members besides the second casing may be positioned between the first casing and the lid. In this case, the fin extension may face the outer circumferential surface of the other member.

[0074] In the first embodiment described above, the end of the power supply line 8 opposite to the coil end is pulled out to the outside by passing through the through hole 61a of the second cylindrical portion 61. However, the opposite end of the power supply line may be pulled out to the outside from another part of the casing. For example, the first cylindrical portion or the lid portion may have a through hole for pulling the power supply line to the outside.

[0075] In each of the above embodiments, the motors 100 and 101 have a sensor unit 9. However, the motors do not need to have a sensor unit.

[0076] In each of the above embodiments, the sensor unit 9 has a rotation angle detection unit 91 and a signal output unit 92, and detects the rotation angle of the rotor 3. However, the sensor unit may also be a sensor that detects other information about the rotor. For example, the sensor unit may have a rotation position detection unit that detects the rotation position of the rotor. The rotation position detection unit may be, for example, a Hall sensor.

[0077] In each of the above embodiments, the sensor unit 9 is fixed to one axial side A1 of the partition plate portion 62 of the second casing 6, 106. However, the sensor unit may be fixed to a member other than the partition plate portion.

[0078] In each of the above embodiments, the first cylindrical portion 51, the plurality of fins 52, and the bottom portion 53 are made of aluminum. The second cylindrical portions 61, 161 are made of resin. However, the first cylindrical portion, the plurality of fins, and the bottom portion may be made of a material other than aluminum. The second cylindrical portion may be made of a material other than resin.

[0079] In each of the above embodiments, the first cylindrical portion 51 and the plurality of fins 52 are made of a material with a higher thermal conductivity than the second cylindrical portions 61 and 161. However, the first cylindrical portion and the plurality of fins may be made of a material with the same thermal conductivity as the second cylindrical portion.

[0080] In each of the above embodiments, the first cylindrical portion 51 has a flange portion 511 that extends radially outward at one end on the axial side A1. However, the first cylindrical portion does not have to have a flange portion that extends radially outward at one end on the axial side.

[0081] In each of the above embodiments, the first cylindrical portion 51 has an inclined surface 511a connected to the flange portion 511 on the outer circumferential surface of the end on one side A1 in the axial direction. However, the first cylindrical portion does not have to have an inclined surface on the outer circumferential surface of the end on one side in the axial direction.

[0082] In each of the above embodiments, the first cylindrical portion 51 and the plurality of fins 52 are integrally molded. However, the first cylindrical portion and the plurality of fins 52 may be separate parts.

[0083] In each of the above embodiments, the radial inner surface of the fin extension 521 is radially separated from the outer circumferential surfaces of the second cylindrical portions 61 and 161. However, the radial inner surface of the fin extension may be in contact with the outer circumferential surface of the second cylindrical portion.

[0084] In each of the above embodiments, the first casing 5 has a third fin 52c that is shorter in the axial direction A than the first cylindrical portion 51. However, the first casing does not have to have a fin that is shorter in the axial direction than the first cylindrical portion.

[0085] In each of the above embodiments, the third fin 52c, which is shorter in the axial direction A than the first cylindrical portion 51, is located on the other axial side A2 relative to the fixing projection 41. However, fins located at other positions on the first cylindrical portion may be shorter in the axial direction than the first cylindrical portion.

[0086] In each of the above embodiments, the second fin 52b, which is longer in the axial direction A than the first cylindrical portion 51, does not protrude in the other axial direction A2 than the first cylindrical portion 51, but protrudes in one axial direction A1 than the first cylindrical portion 51. However, the second fin, which is longer in the axial direction than the first cylindrical portion, may protrude in the other axial direction than the first cylindrical portion, but may not protrude in one axial direction than the first cylindrical portion. The second fin, which is longer in the axial direction than the first cylindrical portion, may protrude in both one axial direction and the other axial direction than the first cylindrical portion.

[0087] In each of the above embodiments, all fin extensions 521 extend to the axial end A1 of the lid 7. However, some fin extensions do not need to extend to the axial end of the lid.

[0088] Furthermore, in a configuration where the second casing has a partition plate portion that covers one axial side A1 of the second cylindrical portion, it is preferable that the fin extension portion extends at least to the end of the partition plate portion on one axial side.

[0089] This results in a motor with a larger surface area of ​​fins compared to a motor where the fins do not extend to one end of the partition plate portion in the axial direction. Therefore, the heat dissipation performance of the motor can be further improved.

[0090] Furthermore, in a configuration where the casing has a cover portion that covers one axial side of the second casing, it is preferable that the fin extension portion extends to the axial end of the cover portion.

[0091] This results in a motor with a larger surface area of ​​fins compared to a motor where the fins do not extend to the axial end of the cover portion that covers one axial side of the casing. Therefore, the heat dissipation performance of the motor can be further improved.

[0092] In each of the above embodiments, the other axial side A2 of all fins 52 extends to the other axial side A2 end of the first cylindrical portion 51. However, the other axial side of some or all of the fins does not have to extend to the other axial side end of the first cylindrical portion.

[0093] In the above embodiment 1, the fin extension 521 is located at a different position from the through hole 61a when viewed in the axial direction A. However, the fin extension may be located at a position that overlaps with the through hole when viewed in the axial direction, as long as it does not overlap with the through hole when viewed in the radial direction. That is, the fin extension may be located on the other side of the through hole in the axial direction.

[0094] In the modified embodiment 1 described above, the fin extension 521 is located at a different position from the connection terminal 163 when viewed in the axial direction A. However, the fin extension may be located at a position that overlaps with the connection terminal when viewed in the axial direction, as long as it does not overlap with the connection terminal when viewed in the radial direction. That is, the fin extension may be located on the other axial side of the connection terminal.

[0095] In each of the above embodiments, in the first cylindrical portion 51, a third fin 52c is located on the other axial side A2 relative to the fixing projection 41, and is shorter in the axial direction A than the first cylindrical portion 51. However, a fin does not necessarily have to be located on the other axial side relative to the fixing projection.

[0096] In each of the above embodiments, the second casings 6 and 106 house wiring sections such as the power supply line 8 and the signal output section 92. However, the second casing does not have to house wiring sections. The second casing may house other components within the motor, or it may not house anything at all. For example, the second casing may be a spacer that adjusts the axial length of the motor.

[0097] In each of the above embodiments, the second casing 6, 106 has a partition plate portion 62 that covers one axial side A1 of the second cylindrical portion 61, 161. However, the second casing does not have to have a partition plate portion 62. The second casing may have a partition plate portion located inside the second cylindrical portion. The second casing may have a partition plate portion that covers the other axial side of the second cylindrical portion.

[0098] In the above embodiment 1, the second cylindrical portion 61 has a through hole 61a that penetrates in the radial direction. However, the second cylindrical portion does not have to have a through hole that penetrates in the radial direction.

[0099] In each of the above embodiments, the central portion of the partition plate 62 is recessed in the other axial direction A2. However, the central portion of the partition plate does not have to be recessed in the other axial direction.

[0100] In each of the above embodiments, the first casing 5, the second casings 6, 106, and the lid 7 each have fixing protrusions 41 that project radially outward. The fixing protrusions 41 have fastening holes 42 into which fastening members F are inserted axially. The first casing 5, the second casings 6, 106, and the lid 7 are fixed to each other by fastening members F inserted into the fastening holes 42 of the fixing protrusions 41. However, the first casing, the second casing, and the lid do not each have fixing protrusions that project radially outward. The fixing protrusions do not have fastening holes into which fastening members are inserted axially. The first casing, the second casing, and the lid may be fixed to each other by other means.

[0101] (Example Configuration) This technology can also be configured as follows:

[0102] (1) The motor comprises a cylindrical stator extending axially about a central axis, a rotor located radially inward from the stator and rotating about the central axis, and a casing housing the stator and the rotor. The casing has a first casing located radially outward from the stator. The first casing has a cylindrical first cylindrical portion whose inner circumferential surface contacts the outer circumferential surface of the stator, and a plurality of fins located on the outer circumferential surface of the first cylindrical portion and extending axially along the outer circumferential surface of the first cylindrical portion. At least one of the plurality of fins has a fin extension that protrudes axially beyond the axial end of the first cylindrical portion.

[0103] (2) In the motor described in (1), the casing has a second casing which is arranged on one side in the axial direction relative to the first casing. The second casing has a cylindrical second cylindrical portion which is located on one side in the axial direction relative to the first cylindrical portion. The fin extension protrudes axially from the first cylindrical portion and faces the outer circumferential surface of the second cylindrical portion.

[0104] (3) In the motor described in (2), the first cylindrical portion and the plurality of fins of the first casing are made of a material with a higher thermal conductivity than the second cylindrical portion of the second casing.

[0105] (4) In the motor described in (3), the first cylindrical portion and the plurality of fins of the first casing are made of aluminum. The second cylindrical portion of the second casing is made of resin.

[0106] (5) In the motor described in any one of (2) to (4), the radial inner surface of the fin extension is radially separated from the outer circumferential surface of the second cylindrical portion.

[0107] (6) In the motor described in any one of (2) to (5), the first cylindrical portion of the first casing has a flange portion that extends radially outward at one end on the axial side.

[0108] (7) In the motor described in any one of (2) to (6), the second cylindrical portion of the second casing has a through hole that penetrates in the radial direction. The fin extension is located at a position different from the through hole when viewed in the axial direction.

[0109] (8) The motor described in any one of (2) to (7) has a wiring section arranged in the axial direction relative to the stator. The second casing houses the wiring section. The second cylindrical portion of the second casing has a radially penetrating connection terminal portion to which the wiring section is electrically connected and to which an external device is electrically connected. The fin extension portion is located in a position different from the connection terminal portion when viewed in the axial direction.

[0110] (9) In the motor described in any one of (2) to (8), the second casing has a partition plate portion that covers one axial side of the second cylindrical portion. The fin extension portion extends at least to the end on one axial side of the partition plate portion.

[0111] In the motor described in any one of (10)(2) to (9), the casing has a cover portion that covers one axial side of the second casing. The fin extension portion extends to the axial end of the cover portion.

[0112] In the motor described in (11)(10), the first casing, the second casing, and the lid each have a projection that protrudes radially outward. The projection has a fastening hole into which a fastening member is inserted in the axial direction. The first casing, the second casing, and the lid are fixed to each other by the fastening member inserted into the fastening hole of the projection. The plurality of fins include fins located on the other axial side with respect to the projection.

[0113] The present invention is applicable to a motor in which heat dissipation fins are located on the outer circumferential surface of the casing that houses the rotor and stator.

[0114] 2 Stator 21 Stator core 22 Stator coil 221 Coil end 3 Rotor 4, 104 Casing 41 Fixing projection (projection) 42 Fastening hole 5 First casing 51 First cylindrical part 511 Flange part 511a Inclined surface 52 Fin 52a First fin (fin) 52b Second fin (fin) 52c Third fin (fin) 521 Fin extension part 53 Bottom part 6, 106 Second casing 61, 161 Second cylindrical part 611 Projection 61a Through hole 62 Partition plate part 62a Through hole 7 Cover part 8 Power supply line (wiring part) 9 Sensor unit 91 Rotation angle detection part 92 Signal output part (wiring part) 100, 101 Motor 163 Connection terminal part

Claims

1. A motor comprising: a cylindrical stator extending axially about a central axis; a rotor located radially inward from the stator and rotating about the central axis; and a casing housing the stator and the rotor, wherein the casing has a first casing located radially outward from the stator, and the first casing has a cylindrical first cylindrical portion whose inner circumferential surface contacts the outer circumferential surface of the stator, and a plurality of fins located on the outer circumferential surface of the first cylindrical portion and extending axially along the outer circumferential surface of the first cylindrical portion, and at least one of the plurality of fins has a fin extension that protrudes axially beyond the axial end of the first cylindrical portion.

2. A motor according to claim 1, wherein the casing has a second casing disposed on one axial side with respect to the first casing, the second casing has a cylindrical second cylindrical portion located on one axial side with respect to the first cylindrical portion, and the fin extension protrudes axially from the first cylindrical portion and faces the outer circumferential surface of the second cylindrical portion.

3. A motor according to claim 2, wherein the first cylindrical portion of the first casing and the plurality of fins are made of a material with a higher thermal conductivity than the second cylindrical portion of the second casing.

4. A motor according to claim 3, wherein the first cylindrical portion and the plurality of fins of the first casing are made of aluminum, and the second cylindrical portion of the second casing is made of resin.

5. A motor according to any one of claims 2 to 4, wherein the radial inner surface of the fin extension is radially separated from the outer circumferential surface of the second cylindrical portion.

6. A motor according to any one of claims 2 to 4, wherein the first cylindrical portion of the first casing has a flange portion that extends radially outward at one end on the axial side.

7. A motor according to any one of claims 2 to 4, wherein the second cylindrical portion of the second casing has a through hole that penetrates radially, and the fin extension is located at a position different from the through hole when viewed in the axial direction.

8. A motor according to any one of claims 2 to 4, wherein the motor has a wiring section arranged in the axial direction relative to the stator, the second casing houses the wiring section, the second cylindrical section of the second casing has a radially penetrating connection terminal section to which the wiring section is electrically connected and to which an external device is electrically connected, and the fin extension section is located at a position different from the connection terminal section when viewed in the axial direction.

9. A motor according to any one of claims 2 to 4, wherein the second casing has a partition plate portion that covers one axial side of the second cylindrical portion, and the fin extension portion extends at least to the end on one axial side of the partition plate portion.

10. A motor according to any one of claims 2 to 4, wherein the casing has a cover portion that covers one axial side of the second casing, and the fin extension portion extends to the axial end of the cover portion.

11. A motor according to claim 10, wherein the first casing, the second casing, and the lid each have a projection that protrudes radially outward, the projection has a fastening hole into which a fastening member is inserted in the axial direction, the first casing, the second casing, and the lid are fixed to each other by the fastening member inserted into the fastening hole of the projection, and the plurality of fins include fins located on the other axial side with respect to the projection.

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