Fan structure

Abstract

To efficiently cool the motor. [Solution] In a fan structure for cooling a motor (11) with a fan (41) having a blade (43) that blows air radially outward and an extension (42v) that extends radially outward from the blade (43), the extension (42v) has a curved portion (42w) that curves toward the motor (11) located on one side in the axial direction of the fan (41), and the end of the curved portion (42w) is positioned opposite the coil portion (13b) of the motor (11).

Description

Technical Field

[0001] The present invention relates to a fan structure.

Background Art

[0002] In recent years, efforts toward realizing a low-carbon society or a decarbonized society have intensified, and research and development on motor cooling technology has been conducted in vehicles as well to reduce CO2 emissions and improve energy efficiency. Patent Document 1 describes a fan structure that cools a motor with a fan provided with blades that send air in the centrifugal direction and an extending portion that extends further radially outward than the blades. In the fan structure of Patent Document 1, as the fan rotates, air outside the case is taken into the case from an intake port provided in the case, passes through the fan and the stator in sequence, and then is discharged to the outside from an exhaust port provided in the case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0004] Meanwhile, in the technology of cooling a motor with a fan, efficient cooling of the motor is a challenge. The present application is made to solve the above problem, with the objective of efficiently cooling a motor. In turn, this contributes to improved energy efficiency.

Means for Solving the Problem

[0005] As one aspect of the present disclosure, a fan structure is provided for cooling a motor by a fan having blades that send air radially outward and an extension portion that extends radially outward from the blades, wherein the extension portion includes a curved portion that curves toward the motor located on one side in the axial direction of the fan, and the end of the curved portion is positioned opposite the coil portion of the motor. [Effects of the Invention]

[0006] According to the present invention, it becomes possible to efficiently cool the motor. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows a power unit to which the fan structure according to this embodiment is applied, viewed from the opposite side of the output shaft. [Figure 2] Figure 2 shows the motor's surrounding structure with the case cover removed. [Figure 3] Figure 3 shows Figure 2 with the fan removed. [Figure 4] Figure 4 is a perspective view showing a partial cross-section of the insulator and fan. [Figure 5] Figure 5 shows the fan and case cover from the motor side. [Figure 6] Figure 6 shows the fan unit from the front, side, and rear. [Figure 7] Figure 7 is a cross-sectional view taken along the line VI-VI in Figure 1. [Figure 8] Figure 8 is a magnified view of a portion of Figure 7. [Modes for carrying out the invention]

[0008] [1. Embodiments] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows a power unit 1 to which the fan structure according to this embodiment is applied, viewed from the opposite side of the output shaft 21. This embodiment shows an example of a fan structure mounted on the power unit 1, and the configuration of the power unit 1, including this fan structure, will be described below. The power unit 1 comprises a case 31 that houses a motor 11 and has an output shaft 21, and the output shaft 21 is rotationally driven by the motor 11. In Figure 1, the reference numeral C1 indicates the motor axis located at the center of the rotation axis 12 of the motor 11. Also, the reference numeral C2 in Figure 1 indicates the output axis located at the center of rotation of the output shaft 21. The motor axis C1 and the output axis C2 are arranged parallel to each other. In the illustrated example, the motor axis C1 and the output axis C2 are arranged parallel to each other, but this is just one example, and the two axes may be arranged intersecting or at an angle.

[0009] Specific examples of devices utilizing the power unit 1 include electric vehicles such as saddle-type vehicles, four-wheeled vehicles and work machines, robots, flying vehicles, water-based vehicles and underwater vehicles. The power unit 1 may also be applied to devices other than mobile vehicles. The position of the power unit 1 and its orientation (front / back or up / down) may be changed depending on the configuration and available space of the device. Furthermore, the motor axis C1 and the output axis C2 may not be parallel.

[0010] The case 31 has a case cover 31a that covers the area corresponding to the motor 11 from the side, and the case cover 31a is detachable. Figure 2 shows the motor surrounding structure with the case cover 31a removed. As shown in Figure 2, the motor 11 comprises a stator 13 fixed to the case 31 and a rotor 14 located on the inner circumference of the stator 13. The central axes of the stator 13 and rotor 14 coincide with the motor axis C1. A fan 41 is fixed to the rotor 14.

[0011] The fan 41 is made of a resin material with a higher thermal conductivity than general resin materials. For example, PPS (polyphenylene sulfide) containing a thermally conductive filler can be used. PPS has an extremely high thermal conductivity (approximately 20-23 W / m·K) for a resin and has superior heat dissipation compared to general resins (approximately 0.2-0.5 W / m·K), thus contributing to improved motor cooling performance while suppressing the temperature rise of the fan 41. The fan 41 is integrally fixed to the rotor 14 and rotates integrally with the rotation of the rotor 14. The rotation axis of the fan 41 is configured to coincide with the motor axis C1.

[0012] The fan 41 has a disc shape that overlaps with the rotor 14 and stator 13 when viewed from the direction of the motor axis as shown in Figure 2. Since the motor axis C1 coincides with the axis of the fan 41, viewing from the direction of the motor axis is equivalent to viewing from the direction of the fan axis.

[0013] Figure 3 shows Figure 2 with the fan 41 removed. As shown in Figure 3, the stator 13 comprises a stator core 13a formed in an annular shape, a coil section 13b, and an insulator 13d (Figure 7) arranged to cover each coil winding section of the stator core 13a. The insulator 13d is made of an insulating material and ensures electrical insulation from the stator core 13a, and also functions as a winding frame for the coil section 13b. More specifically, the stator core 13a has a plurality of coil winding sections arranged radially with respect to the motor axis C1, and the coil section 13b is formed by winding a coil around each coil winding section via the insulator 13d. Between each coil section 13b, a stator communication passage 13c is formed, which is an opening that connects the stator 13 in the direction along the motor axis C1.

[0014] Figure 4 is a perspective view showing a partial cross-section of the insulator 13d and the fan 41. As shown in Figure 4, the insulator 13d includes a winding portion 13e around which a coil is wound, a fan-side outer peripheral flange portion 13f protruding toward the fan 41 on the outer peripheral side of the winding portion 13e, and a fan-side inner peripheral flange portion 13g protruding toward the fan 41 on the inner peripheral side of the winding portion 13e. Further, the insulator 13d includes a fan-opposite-side outer peripheral flange portion 13h protruding to the side opposite to the fan 41 on the outer peripheral side of the winding portion 13e, and a fan-opposite-side inner peripheral flange portion 13j protruding to the side opposite to the fan 41 on the inner peripheral side of the coil portion 13b.

[0015] The stator communication passage 13c functions as a stator-side air passage that serves as a path for airflow generated by the fan 41, and also contributes to weight reduction of the stator 13. In the example of Figure 3, the coil portions 13b are arranged at 30-degree intervals, and accordingly, the stator communication passages 13c are also formed at 30-degree intervals. Note that the structures related to the stator core 13a and the coil portion 13b of the stator 13 can be modified as appropriate.

[0016] The rotor 14 has a rotor core 14a, and a shaft fixing hole 14b to which the rotating shaft 12 of the motor 11 is fixed is formed at the center of the rotor core 14a. In addition to the shaft fixing hole 14b, the rotor 14 is provided with rotor through-holes 14c which are openings penetrating in the axial direction of the rotor 14.

[0017] The rotor through-holes 14c have first rotor through-holes 14c1 extending radially with the motor axis C1 as a reference, and second rotor through-holes 14c2 formed between the first rotor through-holes 14c1 adjacent in the circumferential direction. Each first rotor through-hole 14c1 is formed as a linear large-opening through-hole that maintains a constant width from the shaft fixing hole 14b to a position close to the outer peripheral surface of the rotor 14 when viewed from the motor axial direction. These first rotor through-holes 14c1 are through-holes of the same shape arranged at equal angles (for example, 45 degrees) with the motor axis C1 as a reference.

[0018] The second rotor through-hole 14c2 is formed as a fan-shaped (including inverted triangular) through-hole that widens circumferentially towards the outer circumference. This shape allows for the efficient formation of a large opening through-hole between adjacent first rotor through-holes 14c1. The first rotor through-holes 14c1 and the second rotor through-holes 14c2 function as rotor-side air passages that allow air from the fan 41 to pass through, and also contribute to reducing the weight of the rotor 14. In this configuration, the first rotor through-hole 14c1 has a larger opening than the second rotor through-hole 14c2, and the second rotor through-hole 14c2 is an auxiliary opening formed using the area between the first rotor through-holes 14c1. This ensures an appropriate amount of airflow for cooling the rotor 14 and reduces the weight of the rotor 14. Note that the shape and number of the first rotor through-holes 14c1 and the second rotor through-holes 14c2 may be changed as appropriate.

[0019] Figure 3 shows the outline of the fan 41 with a dashed line. As shown in Figure 3, the fan 41 is positioned on one axial side of the motor 11 and is sized to cover the entire rotor 14 and the coil portion 13b of the stator 13 when viewed from the direction of the motor axis.

[0020] Figure 5 shows the fan 41 and case cover 31a from the motor 11 side. For ease of explanation, the position of the coil section 13b is also shown in Figure 5. Furthermore, Figure 5 also shows a perspective view of the fan 41. Figure 6 shows the fan 41 alone from the front, side, and rear, and Figure 7 shows the cross-sectional view VI-VI in Figure 1.

[0021] Refer to Figures 5 to 7 to explain the fan 41. The fan 41 is a centrifugal fan and comprises a disc-shaped base plate 42 perpendicular to the rotation axis 12 of the motor 11, and a plurality of blades 43 protruding from the base plate 42 toward the motor 11. The blades 43 are composed of identically shaped blades arranged at equal angles with respect to the motor axis C1. The fan 41 is fixed to the rotor 14 and rotates together with the rotor 14. The blade 43 is configured as a so-called "radial blade," for example, one that does not tilt forward or backward with respect to the direction of rotation. That is, the blade 43 extends linearly along the radial direction and has no angle of inclination with respect to the direction of rotation.

[0022] The blade 43 has a shape that extends radially from the fan 41, and integrally comprises, in order from the inner circumference, an inner circumferential blade portion 43a that constitutes the intake end, an intermediate blade portion 43b that extends radially outward from the inner circumferential blade portion 43a to the fan 41, and an outer circumferential blade portion 43c that constitutes the radially outward end of the intermediate blade portion 43b. By adopting a radial blade structure, the blade 43 can ensure sufficient rigidity even when small, and realizes a flow that is less affected by dust and air resistance, thereby contributing to both miniaturization of the power unit 1 and cooling efficiency.

[0023] The inner circumferential blade portion 43a has a linear shape in which the amount of protrusion from the base plate 42 increases as it moves radially outward from the fan 41, and functions as an "inner circumferential inclined portion". As shown in Figure 7, the inner circumferential blade portion 43a is positioned in the axial direction of the fan 41 (coinciding with the axial direction of the rotor 14) to overlap with the rotor through-hole 14c, which consists of the first rotor through-hole 14c1 and the second rotor through-hole 14c2. This configuration allows for efficient suction of air from within the rotor through-hole 14c when the fan 41 is rotating. By positioning the inner circumferential blade portion 43a radially outward from the rotor through-hole 14c, the air from within the rotor through-hole 14c can be efficiently directed to the outer circumference by the inner circumferential blade portion 43a.

[0024] The intermediate blade section 43b has a plate-like blade shape that ensures a sufficient amount of protrusion from the base plate 42. In this configuration, as shown in Figures 5 to 7, the protruding end of the fan 41 in the axial direction is formed to be a straight section 43b1 (Figure 7) that extends parallel to the end face 14t (Figure 7) of the rotor 14. As shown in Figure 7, the intermediate blade section 43b is provided in the region of the fan 41 that overlaps with the end face 14t of the rotor 14 in the axial direction, and the straight section 43b1 is positioned close to the end face 14t of the rotor 14 with a very small gap. This suppresses air leakage from between the rotor 14 and the blade 43, and allows air to flow efficiently radially outward.

[0025] Furthermore, the straight portion 43b1 of the intermediate blade portion 43b may be configured to abut against the end face 14t of the rotor 14. In this case, it is possible to further suppress air leakage from between the rotor 14 and the blade 43.

[0026] As shown in Figure 7, the outer peripheral blade portion 43c is located on the inner circumference side of the coil portion 13b of the motor 11, and in close proximity to the coil portion 13b. As shown in Figure 7, in the motor 11, the stator 13 is configured to protrude further than the rotor 14 in the axial direction of the motor 11 (coinciding with the axial direction of the fan 41). In other words, the coil portion 13b protrudes further outward in the axial direction of the fan 41 than the rotor 14.

[0027] By positioning the outer peripheral blade portion 43c on the inner peripheral side of the coil portion 13b, the blade 43 and the coil portion 13b do not overlap in the axial direction of the fan 41, making it possible to position the blade 43 close to the rotor 14. As a result, as shown in Figure 7, the blade 43 can be positioned to overlap with the coil portion 13b in the radial direction of the fan 41. Therefore, the space on the inner peripheral side of the coil portion 13b and on the axially outer side of the rotor 14 can be effectively utilized as space for positioning the blade 43.

[0028] In this configuration, as shown in Figures 5 and 6, the base plate 42 is provided with an extension portion 42v that extends radially outward from the blade 43. The extension portion 42v is formed around the entire circumference of the base plate 42 (corresponding to the entire circumference with respect to the rotation axis of the base plate 42), and its outer peripheral end forms a curved portion 42w that curves along the entire circumference toward one side in the axial direction of the fan 41 (towards the motor 11). The radial length of the extension portion 42v (corresponding to the radial length with respect to the rotation axis of the extension portion 42v) is formed to be at least one-fifth of the radial length of the blade 43.

[0029] More specifically, the curved portion 42w is formed in a shape that curves toward the coil portion 13b side of the stator 13, as shown in Figure 7. Figure 7 shows the case where the curved portion 42w is curved in an arc shape, but this curved shape is not limited to an arc shape, and it can also be a polygonal shape or a linear shape that slopes toward the coil portion 13b side.

[0030] Figure 8 is a magnified view of a portion of Figure 7. Figures 7 and 8 show the airflow from fan 41 indicated by arrows W. As shown in Figure 8, the airflow W flowing radially outward by the blade 43 is efficiently guided radially outward by the extension 42v of the base plate 42. The outer peripheral portion of the extension 42v is provided with a curved portion 42w that curves toward the motor 11, and the end of the curved portion 42w is positioned opposite the coil portion 13b of the motor 11 in the direction of the fan axis.

[0031] The curved section 42w smoothly redirects the airflow W in the axial direction, suppressing flow separation and pressure loss due to cross-sectional changes. As a result, the airflow W is efficiently guided to the coil section 13b. A stator communication passage 13c (Figure 3) is formed in the coil section 13b, penetrating in a direction along the motor axis C1, allowing the airflow W directed by the curved section 42w to flow effectively into the stator communication passage 13c. Furthermore, by appropriately setting the clearance between the end of the curved section 42w and the coil section 13b, the axial flow velocity is maintained and a uniform flow field is formed around the coil section 13b, thereby improving cooling performance.

[0032] As shown in Figure 8, the insulator 13d includes a fan-side outer peripheral flange portion 13f that protrudes toward the fan 41 on the outer circumference of the coil portion 13b, and a fan-side inner peripheral flange portion 13g that protrudes toward the fan 41 on the inner circumference of the coil portion 13b. Furthermore, the insulator 13d includes a fan-opposite outer peripheral flange portion 13h that protrudes toward the opposite side of the fan 41 on the outer circumference of the coil portion 13b, and a fan-opposite inner peripheral flange portion 13j that protrudes toward the opposite side of the fan 41 on the inner circumference of the coil portion 13b.

[0033] The curved portion 42w is positioned on the inner circumference side of the fan-side outer circumference flange portion 13f of the insulator 13d, and on the outer circumference side of the fan-side outer circumference flange portion 13f in the motor axis direction, and at least a portion of the curved portion 42w is positioned on the outer circumference side of the fan-side inner circumference flange portion 13g. This arrangement allows the curved portion 42w to form a flow path that more efficiently guides the air W from between the fan-side outer circumference flange portion 13f and the fan-side outer circumference flange portion 13g to the coil portion 13b and the stator communication passage 13c.

[0034] As shown in Figure 8, the rotating shaft 12 of the motor 11 is rotatably supported by a pair of support parts 51a and 51b that are spaced apart with the rotor 14 in between. The support parts 51a and 51b have a structure that supports the rotating shaft 12 via bearings 52a and 52b, and are integrally formed with the case 31.

[0035] The case 31 has a space K1 on the opposite side of the fan 41, with the rotor 14 in between, which communicates with the stator communication passage 13c and the rotor through-hole 14c. This space K1 functions as a sealed space that does not communicate with the space outside the case 31, but "sealed" in this disclosure is not limited to a completely airtight seal. That is, the space K1 only needs to be isolated from the outside to the extent that the cooling air inside can be circulated, and the case 31 may be provided with air holes (breathers) to prevent an excessive rise in internal pressure. The space K1 has a first gap K2 between the support portion 51a, located on the opposite side of the fan 41 with the rotor 14 in between, and the rotor 14, which is recessed further inward than the rotor through-hole 14c.

[0036] The first gap K2 between the support portion 51a and the rotor 14 is recessed inward from the rotor through-hole 14c, allowing the fan 41 to efficiently draw air from the first gap K2 into the rotor through-hole 14c. More specifically, the first gap K2 is defined as a three-dimensional continuous space based on the spaced-apart shape of the support portion 51a and the rotor 14, and its volume can be larger than the total volume of all rotor through-holes 14c. Due to this volume relationship, the first gap K2 functions as a plenum chamber (static pressure chamber) located upstream of the rotor through-hole 14c, and is presumed to have the effect of uniformly applying the negative pressure generated by the rotation of the fan 41. This uniformity of pressure suppresses unevenness in the air flowing into the rotor through-hole 14c, and the flow is straightened, further improving the suction efficiency.

[0037] Furthermore, in the insulator 13d, the inner surface 13m of the inner flange portion 13j on the opposite side of the fan is formed as a curved surface (hereinafter referred to as the curved surface 13m) that curves along an arc that moves toward the motor axis C1 as it moves away from the rotor 14 in the direction of the motor axis. This curved surface 13m has a shape that continuously covers the periphery of the rotor through-hole 14c with the motor axis C1 as the center, and functions as a guide surface that guides the air in the space K1 toward the rotor through-hole 14c. As a result, excessive diffusion or separation of the airflow in the space K1 is suppressed, and the pressure distribution around the rotor through-hole 14c is stabilized. Consequently, the air inflow into the rotor through-hole 14c becomes uniform and efficient, and the flow resistance when the fan 41 draws air in the space K1 is reduced, thereby improving the cooling efficiency of the rotor 14 and stator 13. Furthermore, the curved surface 13m is not limited to an arc shape; it can be any shape that gradually approaches the motor axis C1 side as it moves away from the rotor 14, and even a linear or multifaceted guide surface can be configured to perform the function of guiding air to the rotor through hole 14c.

[0038] Furthermore, space K1 has a second gap K3 between the support portion 51a and the outer circumference of the case 31, which is recessed on the side away from the stator 13 and rotor 14 in the direction of the motor axis (the direction of the fan 41). The second gap K3 is a region defined as a three-dimensionally continuous three-dimensional space based on the three-dimensional separation shape of the support portion 51a and the case 31, and functions as a space that causes the air W that has passed through the stator communication passage 13c to detour significantly to the side away from the stator 13 and rotor 14 in the direction of the motor axis. As a result, the contact area between the air W, which has been heated after passing through the stator 13, and the case 31 is increased, and furthermore, within the second gap K3, the flow velocity of the air W decreases as the flow path cross-section is expanded, and the contact time when flowing along the inner wall of the case 31 is increased. As a result, heat transfer from the heated air W to the case 31 is performed efficiently, and heat dissipation through the outer wall of the case 31 is promoted. In other words, the second gap K3 forms a heat exchange path that effectively transfers the heat removed from the heat source of the motor 11 to the case 31.

[0039] The second gap K3 is formed in a continuous ring shape around the support portion 51a with the motor axis C1 as the center, and the airflow W that has passed through each stator communication passage 13c flows through this ring space without interruption. As a result, the airflow W comes into contact with the entire circumference of the outer periphery of the case 31, enabling uniform heat dissipation around the entire circumference of the case 31. In addition, the second gap K3 functions as a buffer space that can mitigate pressure fluctuations associated with the rotation of the fan 41 by ensuring the flow volume of the airflow W, thereby stabilizing the flow of cooling air. In this case, if the case 31 is made of a highly thermally conductive material such as metal, the heat dissipation efficiency from the case 31 can be further increased. Furthermore, the heat dissipation efficiency may be further increased by adding cooling fins to the outer surface of the case 31.

[0040] In this configuration, the case 31 does not have an intake port for taking in outside air as cooling air. Instead, an internal circulation cooling structure is configured to dissipate heat to the outside of the case 31 by circulating the air inside the case 31 with a fan 41 and bringing it into contact with the case 31. Specifically, the rotation of the fan 41 draws in air (wind W) through the rotor through hole 14c, which is then blown radially outward by the fan 41, guided axially by the curved section 42w, and then passes through the stator communication passage 13c. Furthermore, the wind W circulates within the space K1 through the second gap K3 and returns to the rotor through hole 14c again through the first gap K2, thereby forming a closed-loop circulation path inside the case 31. Furthermore, in this configuration, by providing a bladeless region K4 radially outside the blade 43 where the blade 43 is absent, interference between the centrifugal flow and the flow guided axially by the fan 41 is reduced, thereby suppressing flow turbulence in the wind W circulation channel.

[0041] As described above, the power unit 1 of this embodiment has a fan structure that cools the motor 11 with a fan 41 that has a blade 43 that sends air radially outward and an extension 42v that is positioned on one axial side of the motor 11 and extends radially outward from the blade 43. The extension 42v has a curved portion 42w that curves toward the motor 11 located on one axial side of the fan 41, and the end of the curved portion 42w is positioned opposite the coil portion 13b of the motor 11 in the direction of the fan axis (corresponding to the direction of rotation axis of the rotor 14 of the motor 11). With this configuration, the wind W sent radially outward by the blade 43 can be guided toward the coil portion 13b by the curved portion 42w, making it possible to efficiently cool the motor 11. By efficiently cooling the motor 11, unnecessary energy consumption can be suppressed and energy efficiency can be improved.

[0042] Furthermore, the blades 43 overlap with the coil portion 13b in the radial direction of the fan 41. This allows the blades 43 to be positioned close to the rotor 14 located on the inner circumference of the coil portion 13b, thereby shortening the axial length required for the arrangement of the motor 11 and fan 41, and contributing to the miniaturization of the device.

[0043] Furthermore, the fan 41 is equipped with a rotor through-hole 14c through which the rotor 14 of the motor 11 passes in the axial direction of the fan 41, and a support part 51a located on the opposite side of the fan 41 that rotatably supports a rotating shaft 12 that rotates integrally with the rotor 14. Between the support part 51a and the rotor 14, there is a first gap K2 that communicates with the rotor through-hole 14c and is recessed inward from the rotor through-hole 14c. This allows air in the first gap K2 to flow smoothly into the rotor through-hole 14c, contributing to an increase in the airflow of the fan 41.

[0044] Furthermore, the blade 43 has an inner circumferential blade portion 43a that functions as an inclined portion on the inner circumference that constitutes the intake end of the fan 41, and at least a part of the inner circumferential blade portion 43a overlaps with the rotor through hole 14c in the axial direction of the fan 41. This allows the fan 41 to efficiently draw in air from the rotor through hole 14c, contributing to an increase in the airflow rate of the fan 41.

[0045] Furthermore, the motor 11 is equipped with a stator 13 on the outer circumference of the rotor 14, and the stator 13 has a coil section 13b and a stator communication passage 13c that penetrates the fan 41 in the axial direction. As a result, the fan 41 forms a circulation path for the air W that cools the stator 13 and the rotor 14, making it possible to efficiently cool the motor 11.

[0046] Furthermore, the blade 43 has a straight section 43b1 parallel to the end face 14t of the rotor 14, and the straight section 43b1 overlaps with at least a portion of the end face 14t in the axial direction of the fan 41. This prevents the air W blown by the blade 43 from leaking between the rotor 14 and the blade 43, making it possible to cool the motor 11 more efficiently.

[0047] Furthermore, a second gap K3 is provided between the outer circumference of the case 31 covering the motor 11 and the support portion 51a, recessed on the side away from the stator 13 and rotor 14 in the direction of the motor axis. As a result, the second gap K3 functions as a space that causes the air W that has passed through the stator communication passage 13c to detour significantly away from the stator 13 and rotor 14 in the direction of the motor axis. Therefore, the contact area between the air W, which has been heated after passing through the stator 13, and the case 31 is increased, and heat dissipation through the outer wall of the case 31 is promoted.

[0048] [2. Other Embodiments] The embodiments described above are merely one aspect of the present invention and can be modified and applied as needed without departing from the spirit of the invention. The fan 41 of the present invention may be applied to various devices as a standalone fan independent of the motor 11, or it may be configured to apply only the motor cooling structure, including the stator 13 and the space K1, independently. Furthermore, the fan structure or cooling structure of the present invention can be applied to any device, such as power tools, home appliances, industrial equipment, and robot actuators.

[0049] Furthermore, the number and shape of the blades 43 and rotor through-holes 14c may be changed, and the shape of the curved section 42w may also be changed. In addition, the blades 43 are not limited to a radial shape, and may be configured as a forward-curved blade that curves forward in the direction of rotation with respect to the motor axis C1, or a backward-curved blade that curves in the opposite direction to the direction of rotation. Since backward-curved blades can be operated with high efficiency, and forward-curved blades have the characteristic of easily obtaining a large airflow even in a small configuration, the optimal blade shape can be selected according to the required cooling performance and device size.

[0050] [3. Configurations supported by the above embodiments] The above embodiment is a specific example of the following configuration.

[0051] (Configuration 1) A fan structure for cooling a motor, comprising a fan having blades that send air radially outward and an extension portion that extends radially outward from the blades, wherein the extension portion includes a curved portion that curves toward the motor located on one side in the axial direction of the fan, and the end of the curved portion is positioned opposite the coil portion of the motor. This configuration allows the airflow, which is blown radially outward by the blades, to be guided toward the coil by the curved section, enabling efficient cooling of the motor.

[0052] (Configuration 2) The fan structure according to Configuration 1, wherein the blades overlap with the coil portion in the radial direction of the fan. This configuration allows the blades to be positioned close to the rotor located on the inner circumference of the coil section, reducing the axial length required for the placement of the motor and fan, and contributing to the miniaturization of the device.

[0053] (Configuration 3) The fan structure according to Configuration 1 or 2, comprising a rotor through hole through which the rotor of the motor passes in the axial direction of the fan, and a support portion that rotatably supports a rotating shaft that rotates integrally with the rotor, wherein a gap is provided between the support portion and the rotor that communicates with the rotor through hole and is recessed inward from the rotor through hole. This configuration allows air in the gap to flow smoothly into the rotor through-hole, contributing to an increase in the fan's airflow.

[0054] (Configuration 4) The fan structure according to Configuration 3, wherein the blade has an inclined portion on the inner circumference that constitutes the intake end of the fan, and at least a part of the inclined portion overlaps with the rotor through hole in the axial direction of the fan. This configuration allows the fan to efficiently draw in air through the rotor holes, contributing to an increase in the fan's airflow.

[0055] (Configuration 5) The fan structure according to any one of Configurations 1 to 4, wherein the motor is provided with a stator on the outer circumference of the rotor, and the stator has the coil portion and a stator communication passage that penetrates the fan in the axial direction. This configuration allows the fan to create a circulating airflow path that cools the stator and rotor, enabling efficient cooling of the motor.

[0056] (Configuration 6) The fan structure according to any one of Configurations 1 to 5, wherein the blade has a straight portion parallel to the end face of the rotor, and the straight portion overlaps with at least a part of the end face in the axial direction of the fan. This configuration prevents airflow from leaking between the rotor and blades, allowing for more efficient cooling of the motor.

[0057] (Configuration 7) The fan structure according to Configuration 5, wherein a second gap is provided between the outer circumference of the case covering the motor and the support portion, the gap being recessed on the side away from the stator and the rotor along the motor axis. In this configuration, the second gap functions as a space that causes the air that has passed through the stator communication passage to detour significantly away from the stator and rotor in the direction of the motor axis. This increases the contact area between the air that has been heated after passing through the stator and the case, and promotes heat dissipation through the outer wall of the case. [Explanation of Symbols]

[0058] 1 Power Unit 11 Motors 12 Rotation axes 13 Stator 13b Coil section 13c Stator Linkage 14 rotors 14c rotor through hole 41 Fans 42 Base plate 42w curved section 42v extension 43 Blades 43a Inner Circumferential Blade Section (Inner Circumferential Inclined Section) 43b1 Straight section 14t rotor end face 51a,51b Support part K1 space K2 First gap (gap that is recessed on the inner circumference side) K3 Second gap K4 Bladeless Area

Claims

1. In a fan structure for cooling a motor (11) with a fan (41) having a blade (43) that blows air radially outward and an extension (42v) that extends radially outward from the blade (43), The extension portion (42v) includes a curved portion (42w) that curves toward the motor (11) located on one side in the axial direction of the fan (41), The end of the curved portion (42w) is positioned opposite the coil portion (13b) of the motor (11). Fan structure.

2. The blade (43) overlaps with the coil portion (13b) in the radial direction of the fan (41). The fan structure according to claim 1.

3. The motor (11) has a rotor through hole (14c) that penetrates the rotor (14) in the axial direction of the fan (41), and a support part (51a) that rotatably supports a rotating shaft (12) that rotates integrally with the rotor (14). Between the support portion (51a) and the rotor (14), there is a gap (K2) that communicates with the rotor through hole (14c) and is recessed inward from the rotor through hole (14c). The fan structure according to claim 1.

4. The blade (43) has an inclined portion (43a) on the inner circumference that constitutes the intake end of the fan (41), At least a portion of the inclined portion (43a) overlaps with the rotor through hole (14c) in the axial direction of the fan (41). The fan structure according to claim 3.

5. The motor (11) is equipped with a stator (13) on the outer circumference of the rotor (14), The stator (13) has the coil portion (13b) and a stator communication passage (13c) that penetrates the fan (41) in the axial direction. The fan structure according to claim 3.

6. The blade (43) has a straight section (43b1) parallel to the end face (14t) of the rotor (14), The straight portion (43b1) overlaps with at least a portion of the end face (14t) in the axial direction of the fan (41). The fan structure according to any one of claims 3 to 5.

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