JP7180277B2 - Rotating body of eddy current reduction gear - Google Patents

Description

The present invention relates to a rotating body included in a reduction gear that is mounted as an auxiliary brake on vehicles such as trucks and buses. More specifically, the present invention relates to a rotating gear included in an eddy current speed reducer (hereinafter also simply referred to as a "speed reducer") using permanent magnets (hereinafter also simply referred to as a "magnet") to generate a braking force. Regarding the body.

Generally, an eddy current speed reducer includes a cylindrical damping member. The braking member is a rotating body attached to the rotating shaft of the vehicle. Usually, a plurality of magnets facing the inner peripheral surface of the rotating body are arranged around the rotation axis. A plurality of pole pieces are arranged around the rotation axis in the gap between the inner peripheral surface of the rotor and the magnet. A switching mechanism switches the position of the magnet relative to the pole piece to switch between damping and non-damping.

During braking, the magnetic flux from the magnet reaches the rotating body through the pole piece. That is, a magnetic circuit is formed between the magnet and the rotor. As a result, eddy currents are generated on the inner peripheral surface of the rotating body that rotates integrally with the rotating shaft. As a result, braking torque acts on the rotating body, and the rotational speed of the rotating shaft decreases. On the other hand, during non-braking, the magnetic flux from the magnet does not reach the rotor. That is, no magnetic circuit is formed between the magnet and the rotating body. Therefore, no eddy current is generated on the inner peripheral surface of the rotating body, and no braking torque is generated.

During braking, the rotating body generates heat as eddy currents are generated. When the rotating body generates heat, the magnet is heated by radiant heat from the rotating body. This is because the rotor surrounds the magnet. If the magnets are overheated, the magnetic force possessed by the magnets is reduced, degrading the performance of the speed reducer. Therefore, it is desirable that the reduction gear includes a mechanism for cooling the rotating body.

A technique for cooling a rotating body is disclosed, for example, in Japanese Patent Application Laid-Open No. 11-113240 (Patent Document 1).

The rotating body of Patent Document 1 is provided with a plurality of cooling fins on its cylindrical outer peripheral surface. As the rotating body rotates, air hits the fins. In addition, the surface area of the rotating body is increased by the fins provided. As a result, the fins can efficiently release the heat generated in the rotating body to the outside.

JP-A-11-113240

The cooling performance of the rotor provided with the fins is improved. This cooling performance depends on the size of the fins. The larger the fins, the higher the cooling performance of the rotor. This is because the contact area between the fins and the air increases. However, since the speed reducer is mounted on the vehicle, the space for arranging the speed reducer is limited. Also, the larger the fins, the heavier the mass of the reduction gear. Furthermore, since the fins are exposed to the outside, they act as a resistance that prevents smooth rotation of the rotating body (rotating shaft). Rotational resistance due to air is also called windage. An increase in windage leads to a decrease in fuel consumption. Therefore, the speed reducer is also required to suppress the windage loss due to the fins.

In addition, if the rotating body provided with fins rotates at high speed, fluid noise is generated. In recent years, there has been a demand for further noise reduction in vehicles equipped with reduction gears. Therefore, the speed reducer is also required to reduce the fluid noise caused by the rotation of the rotating body.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotating body of an eddy current speed reducer that enhances cooling performance while suppressing an increase in size. Another object of the present invention is to provide a rotor for an eddy current reduction gear that can reduce fluid noise.

The rotating body of the eddy current speed reducer according to this embodiment is attached to the rotating shaft. The rotating body includes an outer peripheral surface, fins, and dimples. The outer peripheral surface is cylindrical. The fin includes a surface arranged on the rotational direction side of the rotor, is provided on the outer peripheral surface, and protrudes radially outward of the rotor from the outer peripheral surface. The dimples are arranged on the outer peripheral surface and/or surface.

According to the rotating body of the eddy current speed reducer according to the present invention, the cooling performance can be enhanced while suppressing an increase in size.

FIG. 1 is a cross-sectional view showing an eddy current speed reducer. FIG. 2 is a perspective view of a magnet holding member. FIG. 3 is a diagram showing the magnetic circuit during non-braking. FIG. 4 is a diagram showing a magnetic circuit during braking. FIG. 5 is a perspective view of the rotor. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. FIG. 7 is a diagram showing an analysis model of Example 2 of the present invention. FIG. 8 is a diagram showing an analysis model of Example 3 of the present invention. FIG. 9 is a diagram showing an analysis model of Example 4 of the present invention. FIG. 10 is a diagram showing an analysis model of Example 5 of the present invention. FIG. 11 is a diagram showing the relationship between the heat release amount ratio and the windage loss ratio. FIG. 12 is a diagram showing the relationship between the heat dissipation amount ratio and the weight ratio. FIG. 13 is a schematic diagram showing noise measurement positions in the second embodiment. 14 is a diagram showing the noise test results of Example 2. FIG.

(1) The rotating body of the eddy current speed reducer according to this embodiment is attached to the rotating shaft. The rotating body includes an outer peripheral surface, fins, and dimples. The outer peripheral surface is cylindrical. The fin includes a surface arranged on the rotational direction side of the rotor, is provided on the outer peripheral surface, and protrudes radially outward of the rotor from the outer peripheral surface. The dimples are arranged on the outer peripheral surface and/or surface.

Eddy currents are generated by the permanent magnets in the rotating body of the eddy current type speed reducer. As a result, braking torque acts on the rotating body, and at the same time, the rotating body generates heat. Fins are provided on the outer peripheral surface of the rotating body in order to dissipate the heat generated by the rotating body. The fins increase the surface area of the outer peripheral surface of the rotating body, and when the rotating body rotates, the fins also rotate, and the fins positively come into contact with the air. Therefore, the fins are air-cooled, and the amount of heat released from the rotating body is increased. In order to increase the heat radiation amount of the rotating body by the fins, the fins should be made larger, but the larger the fins, the larger the rotating body and the weight thereof. Therefore, dimples are provided on the outer peripheral surface of the rotor and/or the surface of the fins of the eddy current speed reducer of the present embodiment. As the air flowed by the fins enters the dimples, the air comes into contact with the spherical surfaces of the dimples. As a result, the dimples, that is, the outer peripheral surface of the rotating body are positively air-cooled, and the amount of heat released from the rotating body can be increased without enlarging the fins.

Further, according to the eddy current speed reducer of the present embodiment, the provision of the dimples makes it difficult for the air flowed by the fins to separate from the outer peripheral surface of the rotor and/or the surface of the fins, thereby reducing fluid noise. In addition, the fins do not need to be enlarged in order to increase the amount of heat dissipation by providing the dimples as described above. Therefore, according to the eddy current reduction gear transmission of the present embodiment, it is possible to suppress an increase in windage loss even if the amount of heat radiation is increased.

(2) In the rotating body of (1) above, the fins are preferably inclined with respect to the rotation axis direction.

With such a configuration, one of the two ends of the fins in the direction of the axis of rotation leads the other end in the direction of rotation of the rotor. Therefore, when the rotating body rotates, the air tends to flow in one direction from the leading end of the fin to the other end, and the outer peripheral surface of the rotating body can be stably air-cooled.

(3) In the rotating body of (2) above, the dimples are preferably arranged on the outer peripheral surface and/or the surface of the rotating body on the side where the end of the fin leading in the rotational direction of the rotating body is located rather than the center in the rotational axis direction. .

As shown in Example 1, which will be described later, if dimples are provided on the outer peripheral surface of the rotating body on the side where the leading end of the fin is located (air inflow side), the rotational resistance of the rotating body can be reduced while maintaining the amount of heat dissipation. (windage loss) can be reduced.

(4) In any one of (1) to (3) above, the outer peripheral surface includes two ends in the rotation axis direction of the rotor, and the fins extend from one of the two ends to the other end. preferably extends to

With such a configuration, the fins are provided over the entire outer peripheral surface of the rotating body in the direction of the rotating shaft, so that the rotating body can be uniformly cooled.

[Eddy current speed reducer]
An eddy current speed reducer will be described.

FIG. 1 is a cross-sectional view showing an eddy current speed reducer. FIG. 1 is a cross section along the axis of rotation 10 . The speed reducer 1 includes a first permanent magnet 2 , a second permanent magnet 3 , a magnet holding member 4 and a rotor 5 .

The rotating body 5 is fixed to a rotating shaft 10 (eg, propeller shaft, drive shaft, etc.) of the vehicle via an arm 11 and a wheel 12 . As a result, the rotating body 5 rotates integrally with the rotating shaft 10 . The rotating body 5 corresponds to a braking member to which braking torque is applied by eddy currents. Details of the rotor 5 will be described later.

The magnet holding member 4 has a cylindrical shape and is arranged concentrically with the rotating body. The magnet holding member 4 is rotatably supported around the rotation axis by the housing. The housing is fixed to a non-rotating part (eg, transmission cover) of the vehicle (not shown).

FIG. 2 is a perspective view of a magnet holding member. Referring to FIG. 2 , a first permanent magnet 2 and a second permanent magnet 3 are fixed to the outer peripheral surface of magnet holding member 4 . The first permanent magnet 2 is arranged adjacent to the second permanent magnet 3 in the circumferential direction of the rotating shaft. The first permanent magnet 2 and the second permanent magnet 3 face the inner peripheral surface 15 of the rotor 5 with a gap therebetween (see FIG. 1). The magnetic poles (N pole, S pole) of the first permanent magnet 2 and the second permanent magnet 3 are arranged radially about the rotation axis. The magnetic pole arrangement of the first permanent magnet 2 is different from the magnetic pole arrangement of the second permanent magnet 3 . When the eddy current speed reducer includes a plurality of first permanent magnets 2 and a plurality of second permanent magnets 3, the first permanent magnets and the second permanent magnets are alternately arranged around the rotation axis.

FIG. 3 is a diagram showing the magnetic circuit during non-braking. Referring to FIG. 3, a ferromagnetic pole piece 13 is arranged in the gap between the inner peripheral surface 15 of the rotor 5 and the first permanent magnet 2 and the second permanent magnet 3 . When the eddy current reduction gear transmission 1 includes a plurality of first permanent magnets 2 and a plurality of second permanent magnets 3, a plurality of pole pieces 13 are arranged around the rotation axis. In this case, the arrangement angle of the pole piece 13 around the rotation axis matches the arrangement angle of the first permanent magnet 2 and the second permanent magnet 3 around the rotation axis. The pole piece 13 is held by the housing on both sides.

During non-braking, the pole piece 13 evenly straddles the adjacent first permanent magnet 2 and second permanent magnet 3 . In this state, no braking torque is generated. The magnetic flux emitted from the north pole of one of the adjacent first permanent magnet 2 and second permanent magnet 3 reaches the south pole of the other magnet after passing through the pole piece 13 . The magnetic flux emitted from the N pole of the other magnet reaches the S pole of one magnet through the magnet holding member 4 . In other words, no magnetic circuit is formed between the first permanent magnet 2 and the second permanent magnet 3 and the rotor 5 . Therefore, no braking torque is generated in the rotating body 5 that rotates integrally with the rotating shaft.

FIG. 4 is a diagram showing a magnetic circuit during braking. Referring to FIG. 4, during braking, the magnet holding member 4 rotates about half the angle between the first permanent magnet 2 and the second permanent magnet 3 from the non-braking state. In this case, the pole piece 13 completely overlaps the first permanent magnet 2 or the second permanent magnet 3 .

A magnetic flux emitted from the N pole of one of the adjacent first permanent magnet 2 and second permanent magnet 3 passes through the pole piece 13 and reaches the rotor 5 . The magnetic flux reaching the rotor 5 reaches the S pole of the other magnet through the pole piece 13 . The magnetic flux emitted from the N pole of the other magnet reaches the S pole of one magnet through the magnet holding member 4 . That is, a magnetic circuit is formed between the first permanent magnet 2, the second permanent magnet 3, the magnet holding member 4, the pole piece 13, and the rotor 5, which are adjacent in the circumferential direction. As a result, an eddy current is generated on the inner peripheral surface of the rotor 5 . As a result, braking torque is generated in the rotating body 5 that rotates integrally with the rotating shaft 10 in the direction opposite to the rotating direction. Furthermore, the rotating body 5 generates heat.

A lever (not shown) protrudes from the magnet holding member 4 in parallel with the rotating shaft. A piston rod of an air cylinder is connected to the lever via a link mechanism (not shown). An air cylinder corresponds to a fluid pressure cylinder. The air cylinder is fixed to the housing.

The air cylinder is powered by compressed air according to a command from a control device (not shown). The operation of the air cylinder advances and retracts the piston rod. As the piston rod advances and retreats, the magnet holding member 4 rotates and the positions of the first permanent magnet 2 and the second permanent magnet 3 with respect to the pole piece 13 are switched. This switches between braking and non-braking.

[Rotating body]
Next, the rotor of the eddy current speed reducer according to this embodiment will be described.

FIG. 5 is a perspective view of the rotor. Referring to FIG. 5 , rotating body 5 includes outer peripheral surface 6 , fins 7 and dimples 8 . The outer peripheral surface 6 of the rotating body is cylindrical.

Fins 7 are provided on the outer peripheral surface 6 of the rotating body 5 . The fins 7 may be provided integrally with the outer peripheral surface 6 or may be provided separately. The fins 7 protrude radially outward from the rotating body 5 from the outer peripheral surface 6 . The fins 7 are preferably inclined at a predetermined angle (for example, in the range of 30° to 60°) with respect to the rotation axis direction C of the rotor 5 . The role of the fins 7 is to dissipate heat generated in the rotor 5 .

Fin 7 includes a front surface 9 and a back surface 14 . The surface 9 is arranged on the rotational direction side of the rotating body 5 . The back surface 14 is arranged on the side opposite to the rotating direction of the rotating body 5 . Therefore, when the rotating body 5 rotates (see the arrow in FIG. 5), the front surface 9 more positively contacts the air than the back surface 14. As shown in FIG. The front surface 9 and back surface 14 are along the direction of inclination of the fin. FIG. 5 illustrates the case where the fins are inclined with respect to the direction of the rotation axis, but the rotating body of the eddy current speed reducer according to this embodiment does not exclude fins parallel to the direction of the rotation axis.

A plurality of fins 7 may be provided. As described above, the fins play a role of dissipating the heat of the rotating body, so if a plurality of fins are provided, more heat of the rotating body can be dissipated. It is preferable that the plurality of fins 7 be arranged in parallel at regular intervals in the circumferential direction of the rotor 5 .

Dimples 8 are arranged on the outer peripheral surface 6 of the rotor. Dimple 8 includes a spherical surface. A spherical surface of the dimple 8 is recessed from the outer peripheral surface 6 in a spherical shape. The spherical surface of the dimple 8 has the same shape as part of the surface of the sphere (spherical surface). The role of this dimple will be explained.

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. Referring to FIG. 6, air flows along fins 7 when the rotating body rotates. Then, air also flows over the outer peripheral surface 6 of the rotating body. If there are no dimples on the outer peripheral surface 6 of the rotor, the air will flow linearly along the outer peripheral surface. On the other hand, if the dimples 8 are provided on the outer peripheral surface of the rotor, the air enters the dimples 8 when the air flowing along the outer peripheral surface 6 reaches the dimples 8 . Since the dimples are spherically recessed, the air entering the dimples collides with the spherical surfaces of the dimples. That is, the spherical surface of the dimple is actively air-cooled. As a result, the rotating body provided with dimples is cooled more easily than the rotating body not provided with dimples. As described above, in the rotating body of the eddy current speed reducer according to the present embodiment, the dimples improve the cooling performance of the rotating body. There is no need to increase the size of the fins to improve the cooling performance of the rotor. Therefore, an increase in size of the eddy current speed reducer is suppressed.

Further, the surface area of the outer peripheral surface of the rotating body provided with dimples is larger than the surface area of the outer peripheral surface of the rotating body not provided with dimples. That is, the outer peripheral surface of the rotating body provided with dimples has a larger area in contact with the air than the outer peripheral surface of the rotating body not provided with dimples. Therefore, even if the rotating body is not rotating, the rotating body provided with dimples has higher heat dissipation performance than the rotating body not provided with dimples.

Furthermore, the volume of the rotor is reduced by the dimples. Therefore, by providing the dimples, the weight of the rotating body can be reduced.

In addition, when the rotating body rotates, air flows on the outer peripheral surface of the rotating body, and if the air separates from the outer peripheral surface of the rotating body, fluid noise is generated. In this regard, since the rotating body of the eddy current speed reducer according to the present embodiment is provided with dimples on the outer peripheral surface of the rotating body, separation of air from the outer peripheral surface of the rotating body can be suppressed. Therefore, fluid noise can be suppressed compared to a rotating body that is not provided with dimples. Further, conventionally, it has been necessary to increase the size of the fins of the rotating body in order to increase the amount of heat radiation. However, since the dimples are provided in the eddy current speed reducer according to the present embodiment as described above, the amount of heat dissipation is high even if the fins are not enlarged. Therefore, conventionally, windage loss has been sacrificed in order to ensure the amount of heat radiation, but in the eddy current type reduction gear transmission of the present embodiment, it is possible to suppress an increase in windage loss due to ensuring the amount of heat radiation.

Next, a preferred aspect of the rotor of the eddy current speed reducer according to the present embodiment will be described.

With reference to FIG. 5, the above description describes the case where the dimples are provided on the outer peripheral surface of the rotor. However, the arrangement of dimples is not limited to this case. Dimples may be provided on the surface 9 of the fin. Since the surface 9 of the fins is arranged on the rotational direction side of the rotating body, the surfaces 9 of the fins positively come into contact with the air when the rotating body rotates. Therefore, if dimples are provided on the surface of the fins, the fins can be easily cooled in the same manner as described above. The dimples may be provided only on the outer peripheral surface 6 of the rotor, may be provided only on the fin surfaces 9, or may be provided on both the outer peripheral surface 6 of the rotor and the fin surfaces 9. . Additionally, dimples may be provided on the back surface 14 of the fin.

As shown in Example 1, which will be described later, the dimples 8 are preferably arranged on the outer peripheral surface and/or surface of the fin on the side where the end of the rotating body of the fin precedes in the direction of rotation rather than the center in the direction of the rotation axis 10. . As described above, when the fins are inclined with respect to the rotation axis direction, one of the two ends of the fins in the rotation axis direction precedes the other end in the rotation direction of the rotor. In this case, as the rotating body rotates, air enters from the leading end (inflow side) and flows towards the other end. Here, the dimples 8 promote turbulence of the air flow, thereby suppressing separation of the air flow from the outer peripheral surface and/or surface of the rotating body. By arranging dimples on the outer peripheral surface and/or the surface of the rotor on the air inflow side, it is possible to promote the turbulence of the flow at an early stage when the air flows into the rotor and to suppress the windage loss.

However, as shown in Example 1 which will be described later, even if dimples are provided on the air inflow side of the rotating body, the cooling performance is almost the same as when dimples are provided on the outflow side.

Preferably, the dimples are non-angular in shape. An eddy current is generated on the outer peripheral surface of the rotating body provided with the dimples. Therefore, if the dimples have corners, they may affect the eddy currents generated on the outer peripheral surface, so it is preferable that the dimples have a smooth shape without corners. Therefore, as described above, the dimples need only have a spherical shape rather than a true spherical shape.

The dimple size is not particularly limited. However, if the dimples are too large, the windage loss due to the air entering the dimples will increase. Therefore, it is preferable that the size of the dimples is appropriately set in consideration of both the cooling performance of the rotating body and the windage loss of the rotating body. The same applies to the number of dimples provided on the outer peripheral surface.

The dimples may be formed by machining or may be formed by casting or the like. Further, when the fins are formed separately, the fins may be attached to the outer peripheral surface of the rotor after the dimples are formed on the fins.

In Example 1, thermal fluid analysis was performed in order to confirm the cooling performance of the rotating body of the present embodiment. The calculation was a stationary calculation. A general-purpose software (trade name: ANSYS Fluent 18.1) was used for the thermal fluid analysis. In the analysis, five rotating body models with different dimple arrangements were used as examples of the present invention, and as comparative examples, a rotating body model with no dimples and two rotating body models with different fin heights were used.

[Test conditions]
In Example 1 of the present invention, as shown in FIG. 5, an analysis model was used in which a plurality of dimples were provided on the entire surface of the outer peripheral surface of the rotor and the fins.

FIG. 7 is a diagram showing an analysis model of Example 2 of the present invention. Referring to FIG. 7, in Example 2 of the present invention, an analysis model was used in which a plurality of dimples 8 were provided only on the outer peripheral surface 6 of the rotor on the air outflow side and on the surface 9 of the fin.

FIG. 8 is a diagram showing an analysis model of Example 3 of the present invention. Referring to FIG. 8, in Example 3 of the present invention, an analysis model was used in which a plurality of dimples 8 were provided only on the outer peripheral surface 6 of the rotor on the air inflow side and on the surface 9 of the fin.

FIG. 9 is a diagram showing an analysis model of Example 4 of the present invention. Referring to FIG. 9, in Example 4 of the present invention, an analysis model was used in which a plurality of dimples 8 were provided on the outer peripheral surface 6 of the rotating body on the air inflow side and on the surface 9 of the fin. In the analysis model of Inventive Example 4, the plurality of dimples 8 were arranged in three rows in the direction of the rotational axis of the rotating body.

FIG. 10 is a diagram showing an analysis model of Example 5 of the present invention. Referring to FIG. 10, in Example 5 of the present invention, an analysis model was used in which a plurality of dimples 8 were provided on the outer peripheral surface 6 of the rotor on the air inflow side and on the surface 9 of the fin. In the analysis model of Inventive Example 5, a plurality of dimples 8 were arranged in two rows in the rotational axis direction of the rotating body.

In Examples 1 to 5 of the present invention, the shape of one dimple 8 was the same, and the intervals between the dimples were the same. The spherical surface of one dimple had the same shape as a part of the surface of the sphere (spherical surface). Specifically, the spherical surface was the same as a portion of the surface (spherical surface) of a sphere with a diameter of 5 mm, and the depth of the dimples was 0.5 mm. That is, the dimples are obtained by cutting the sphere into two along a plane perpendicular to the radial direction at a position 0.5 mm in the radial direction of the sphere from an arbitrary point on the surface (spherical surface) of a sphere with a diameter of 5 mm. It had the same shape as the part of the sphere containing the point. Next, a dimple arrangement method will be described with reference to FIG. 5 as an example.

First, the dimples provided on the outer peripheral surface 6 will be described with reference to FIG. The outer peripheral surface 6 of the rotor between the two fins 7 is divided into two parts in the lateral direction (rotational direction in FIG. 5) and 11 parts in the longitudinal direction (inclination direction of the fins 7 in FIG. 5). A dimple is arranged in the center of the divided area of the outer peripheral surface 6 . Next, the dimples provided on the surface 9 of the fin 7 will be explained. The surface 9 of the fin was divided into two parts in the lateral direction (the radial direction of the rotating body in FIG. 5) and 11 parts in the longitudinal direction (inclination direction of the fins 7 in FIG. 5). A dimple was placed in the center of the divided area of the surface 9 of the fin.

In Comparative Example 1, an analytical model was used in which the dimples of Inventive Example 1 were not provided. In Comparative Example 2, a model having a fin height higher than that of the model in Comparative Example 1 by 0.5 mm was used. In Comparative Example 3, a model whose fin height is 1.0 mm higher than that of the model in Comparative Example 1 was used.

Common test conditions for Examples 1 to 5 of the present invention and Comparative Example will be described. The rotation speed of the rotor was 3000 rpm. The temperature around the rotating body (ambient temperature) was 20°C. The temperature of the rotor was uniformly 70°C. The material of the rotor and fins was aluminum having a density of 2719 kg/m ³ , a constant pressure specific heat of 871 J/(kg·K) and a heat transfer coefficient of 202.4 W/(m ² ·K). Table 1 shows the dimensions of the rotors of Examples 1 to 5 of the present invention and Comparative Example 1.

In Table 1, "outer diameter" means the diameter of the outer peripheral surface of the rotor, "width" means the length in the direction of the rotation axis of the rotor, and "number of fins" means the number of fins provided. "Fin angle" means the inclination angle of the fin with respect to the rotation axis, "Fin height" means the length of the fin in the radial direction of the rotating body, and "Fin width" means the distance between the front surface and the back surface of the fin. Means distance (thickness). In Examples 1 to 5 of the present invention, 40 fins were arranged at equal intervals in the circumferential direction of the rotor.

[Test results]
FIG. 11 is a diagram showing the relationship between the heat release amount ratio and the windage loss ratio. The vertical axis indicates the heat dissipation ratio, and the horizontal axis indicates the windage loss ratio. Here, the heat release ratio means the heat release amount of the present invention examples 1 to 5 and the comparative examples 2 and 3 to the heat release amount of the comparative example 1. The amount of heat release was calculated from the product of the heat transfer coefficient around the rotating body and the surface area of the rotating body when the solution reached a steady state in the calculation. The heat transfer coefficient was calculated by dividing the heat flux density on the surface of the rotating body by the difference between the temperature of the rotating body and the ambient temperature (50° C. in Example 1). Further, the windage ratio means the windage loss of Examples 1 to 5 and Comparative Examples 2 and 3 to the windage loss of Comparative Example 1. The windage loss is the moment about the rotation axis of the rotating body that is loaded on the rotating body when the solution reaches a steady state in the calculation. In FIG. 11 , the black circle marks show the results of Invention Example 1, the black triangle marks show the results of Invention Example 2, the black square marks show the results of Invention Example 3, and the black diamond marks show the results of Invention Example 4. Black stars indicate the results of Inventive Example 5, white circles indicate the results of Comparative Example 1, white triangles indicate the results of Comparative Example 2, and white squares indicate the results of Comparative Example 3. show.

With reference to FIG. 11, all of Inventive Examples 1 to 5 had a higher heat release amount than Comparative Example 1 (white circles). Inventive Example 1 (black circles) had a higher heat release rate and lower windage loss than Comparative Example 3 (white squares). In addition, Inventive Examples 2 and 3 (black triangles and black squares) had higher heat dissipation and lower windage loss than Comparative Example 2 (white triangles). In other words, it was found that the provision of dimples can improve the amount of heat dissipation while suppressing the increase in windage loss, compared to the measure of enlarging the fins. In addition, although the amount of heat radiation was the same, windage loss was smaller in Invention Example 3 (black squares) than in Invention Example 2 (black triangles). In other words, it has been found that if dimples are provided on the air inflow side of the rotating body, the windage loss can be reduced while maintaining the cooling performance.

FIG. 12 is a diagram showing the relationship between the heat dissipation amount ratio and the weight ratio. The vertical axis indicates the heat radiation amount ratio, and the horizontal axis indicates the weight ratio. Here, the weight ratio means the weight of the rotor of Examples 1-5 and Comparative Examples 2-3 with respect to the weight of the rotor of Comparative Example 1. The marks in FIG. 12 are the same as in FIG.

Referring to FIG. 12, all of Inventive Examples 1 to 5 were lighter in weight than the rotating body of Comparative Example 1 because the volume of the rotating body was reduced by the amount of dimples provided. On the other hand, in Comparative Examples 2 and 3, although the amount of heat radiation was high, the fins were large, so the weight was increased. In short, according to the rotating body of the present embodiment, it was found that the amount of heat released can be increased to the same level as or higher than the case of enlarging the fins without enlarging the fins.

In Example 2, a noise test was conducted using an actual machine in order to confirm the noise reduction effect of the rotating body of this embodiment. In the noise test, three of each of the two types of rotating bodies of Example 1 of the present invention (see FIG. 5) of Example 1 and Comparative Example 1 were produced by a three-dimensional printer. The material of the rotor was acrylic resin.

[Test conditions]
The common test conditions in Inventive Example 1 and Comparative Example 1 of Example 2 will be described. In the noise test, the three rotors of Inventive Example 1 were tested at 3000 rpm, 3500 rpm and 4000 rpm, respectively. The same was applied to the three rotors of Comparative Example 1. From the data obtained from each noise measurement, the overall value of the sound pressure level (frequency range: 6.25 Hz to 20 kHz) with A-weighting correction was calculated, and the overall value under the same shape and under the same test conditions was arithmetically averaged. . An omnidirectional microphone was used for noise measurement.

FIG. 13 is a schematic diagram showing noise measurement positions in the second embodiment. Referring to FIG. 13, in the noise test, rotating body 5 was attached to rotating tester 20 and rotated. The omnidirectional microphone 21 was arranged at a position separated by a linear distance of 500 mm from the rotation axis 10 .

[Test results]
14 is a diagram showing the noise test results of Example 2. FIG. The vertical axis indicates the A-weighted sound pressure level (dB(A)), and the horizontal axis indicates the rotation speed (rpm) of the rotor. In FIG. 14 , black circles indicate the results of Inventive Example 1, and white circles indicate the results of Comparative Example 1.

In the noise test at each rotation speed, the A-weighted sound pressure level of Inventive Example 1 was lower than that of Comparative Example 1. That is, according to the rotating body of this embodiment, the noise could be reduced more than the rotating body without dimples.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and it goes without saying that various modifications are possible without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention is useful for eddy current speed reducers using permanent magnets.

1: Eddy current speed reducer 2: First permanent magnet 3: Second permanent magnet 4: Magnet holding member 5: Rotating body 6: Outer peripheral surface 7: Fin 8: Dimple 9: Surface 10: Rotating shaft 11: Arm 12: Wheel 13: Pole piece 14: Back surface 15: Inner peripheral surface

Claims (4)

A rotating body of an eddy current reduction gear attached to a rotating shaft,
a cylindrical outer peripheral surface;
fins including a surface disposed on the rotational direction side of the rotating body, provided on the outer peripheral surface, and protruding outward in the radial direction of the rotating body from the outer peripheral surface;
and dimples arranged on the outer peripheral surface and the surface. The rotating body according to claim 1,
The rotating body, wherein the fins are inclined with respect to the rotating shaft direction. The rotating body according to claim 2,
The rotating body, wherein the dimples are arranged only on the outer peripheral surface and the surface on the side where the ends of the fins leading in the rotating direction of the rotating body are located relative to the center in the rotating shaft direction. The rotating body according to any one of claims 1 to 3,
The outer peripheral surface includes two ends in the rotation axis direction of the rotating body,
The body of rotation, wherein the fins extend from one of the two ends to the other end.

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