JP3443825B2 - Rotor for eddy current type reduction gear - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for an eddy current type speed reducer used in large automobiles such as buses and trucks.

[0002]

2. Description of the Related Art Eddy current type speed reducers include those using electromagnets and those using permanent magnets. In any of these systems, an eddy current type speed reducer is proposed in which the surface of the rotor or disk facing the magnet is coated with, for example, copper to form a metal layer of a good electrical conductor for the purpose of improving the generation of braking torque. (Japanese Patent Laid-Open No. 63-2743)
59, JP-A-64-30450, JP-A-1
-288636).

Generally, the rotor of an eddy current type speed reducer is
At the same time as the braking torque is generated by the eddy current during braking, it is heated by the generation of Joule heat and is air-cooled by the cooling fins during non-braking. Therefore, a significant thermal cycle is added by repeatedly turning the braking on and off.
Therefore, in a rotor coated with a good conductor having a different expansion coefficient from that of steel, thermal stress due to the difference in thermal expansion occurs between the rotor and the coating layer, and the coating layer peels off due to repeated occurrence of the thermal stress. Happens.

To alleviate the thermal stress, it has been known that nickel having a coefficient of linear expansion between copper and iron should be interposed between the rotor and the coating layer (Japanese Patent Laid-Open No. 5 (1993) -1993). 236732). Further, a method of dividing the rotor has been proposed in order to reduce the thermal stress of the entire rotor (Japanese Utility Model Publication No. 4-097473).

[0005]

In the rotor of the eddy current type speed reducer coated with the good conductor, the eddy current generated during braking is more concentrated in the coating layer and is exposed to a high temperature exceeding 600 ° C. due to its heating. The frequency is higher than that of the rotor without the coating layer.

When a rotor coated with a metal having good electrical conductivity is exposed to high temperatures, thermal stress is generated due to the difference in linear expansion coefficient between the rotor and the coating layer. However,
Since the rotor of the eddy current type speed reducer repeats heating and cooling by switching between braking and non-braking, the stress generated in the coating layer is repeated compression and tension. As a result, cracking or peeling of the coating layer becomes a problem, and the durability of the coating layer is required.

Generally, when a metal is heated to a temperature higher than 600 ° C., atomic diffusion is activated.
When nickel is interposed between the rotor and the coating layer of the publication, when the temperature of the rotor exceeds 600 ° C., as shown in FIG.
Mutual diffusion becomes active between Ni. And Fe-
In the interdiffusion between Ni, as shown in FIG.
Diffusion holes are likely to occur at the -Ni interface, and eventually FIG. 4 (C).
As shown in (3), the diffusion holes are bonded to each other, and there is a risk that the coating layer peels off due to the generated thermal stress.

The present invention aims to eliminate the peeling phenomenon of the coating layer due to thermal expansion, which is observed in the rotor having the coating layer made of a metal having a good electrical conductivity as described above, and the coating layer is formed in the width direction of the rotor cylindrical portion. The present invention provides a rotor for an eddy current type speed reducer, which is divided into a plurality of pieces in the circumferential direction by a slit provided in the.

[0009]

To achieve the above object, the present invention provides a plurality of permanent magnets or electromagnets such that the rotor fitted to a rotary shaft and the adjacent magnets have opposite polarities. A rotor for an eddy current reducer configured to combine circumscribing support rings with a required gap to generate an eddy current inside a rotor cylinder by a magnetic circuit of a permanent magnet or an electromagnet, the rotor cylinder portion facing the magnet. A coating layer made of copper on the inner peripheral surface of
Provided, plural divided more coating layer circumferentially providing a plurality of slits directed in the width direction of the rotor cylindrical portion to the coating layer.

Further, an oxidation resistant metal film is formed on the surface of the coating layer divided into a plurality in the circumferential direction.

The coating layer is divided into a plurality of portions in the circumferential direction by a large number of slits which coincide with the central axis direction of the rotor cylindrical portion.

The coating layer is divided into a plurality of portions in the circumferential direction by a large number of slits inclined with respect to the central axis direction of the rotor cylindrical portion.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a rotor of an eddy current type speed reducer, a rotor cylindrical portion is coated with a good conductor metal such as copper on the inner peripheral surface facing the magnet with a gap, so that the vicinity of the surface with a high magnetic flux density is provided. The eddy current density is increased, and the braking force can be increased. On the other hand, as the heat load on the coating surface increases, the circumferential component of the thermal stress generated in the coating layer increases.

Here, the coating layer is provided with a large number of slits extending in the width direction of the rotor cylindrical portion and divided into a plurality of portions in the circumferential direction, whereby the circumferential rigidity is reduced and the thermal stress is relieved. As a result, peeling of the coating layer and occurrence of thermal fatigue cracks are suppressed.

Further, since a large amount of eddy current flows in the ridge angle portion formed by the slit due to the edge effect, the Lorentz force generated by the action with the magnetic field increases. Therefore, the edge effect can prevent the coating layer from being reduced and the torque from being reduced by providing the slit. Furthermore, the rotational direction component of the Lorentz force, that is, the braking force can be increased by changing the shape of the slit.

As described above, by dividing the coating layer into a plurality of pieces in the circumferential direction, the thermal stress generated in the coating layer can be reduced, the peeling of the coating layer and the occurrence of thermal fatigue cracks can be suppressed, and the braking force can be reduced. Can be maintained or improved.

Further, by forming an oxidation resistant metal film on the coating layer, oxidation of the coating layer is prevented in a severe thermal environment in which heating and cooling are repeated by a brake operation, and the coating layer is kept in a good condition. Can be maintained.

[0018]

Embodiments of the present invention will be described with reference to the drawings.
The eddy current type speed reducer shown in FIG. 1 is an embodiment in which a copper coating layer 18 is formed on the inner peripheral surface of the rotor 1 facing the magnetic poles of the cylindrical portion according to the present invention.

In the rotor 1, the outer cylinder 2 and the inner cylinder 3 are opposed to each other with a required space to form a cylindrical portion, and the cylinder ends of the outer cylinder 2 and the inner cylinder 3 are connected by a large number of arms 4 to form the outer cylinder 2 A large number of cooling fins 5 are circumferentially arranged on the outer peripheral surface of the inner cylinder 3 at equal intervals, and a mounting disk 6 is provided on one end surface of the inner cylinder 3.

In the space between the outer cylinder 2 and the inner cylinder 3, a support ring 13 having a width matching the length of the cylinder is interposed. The support ring 13 is attached to a support plate 15 axially supported by the rotary shaft 11 via bearings 14, and is supported by a plurality of guide rods 17 projecting in the axial direction of the rotary shaft 11 to support the support ring 13.
By moving the rod 7 penetrating in the width direction forward and backward by the cylinder 10, the length from the position facing the rotor cylindrical portion to the magnetically separated position is provided so as to be forward and backward.

A plurality of permanent magnets 8 are provided around the outer peripheral surface of the support ring 13 so that the polarities of the adjacent magnets are opposite to each other. It should be noted that this permanent magnet group includes a magnetic shield case 12 attached to the support plate 15.
To prevent magnetic leakage. In addition, the magnetic shield case 12 faces the permanent magnet 8 and faces the pole piece 1.
9 are circumferentially arranged.

An outer cylinder 2 forming the cylindrical portion of the rotor 1.
A coating layer 18 made of copper according to an embodiment of the present invention is formed on the inner peripheral surface facing the magnetic pole. The coating layer 18 is, for example, copper-plated to a thickness of about 100 μm by a copper electroplating method. Further, as shown in FIG. 3, an oxidation resistant metal coating 20 of nickel or the like having a thickness of about 10 to 20 μm can be formed on the coating layer 18 by a surface treatment method. In the figure, in order to improve the bonding between the coating layer 18 and the oxidation resistant metal film 20, for example, a Ni-P alloy film 21 is interposed therebetween.

When copper electroplating the rotor cylindrical portion, masking is applied to the surface other than the surface on which the coating layer is formed so as not to come into contact with the strongly acidic plating solution.

Coating layer 18 in accordance with the practice of the invention
Is characterized in that the coating layer is divided into a plurality of pieces in the circumferential direction by a large number of slits extending in the width direction of the rotor cylindrical portion. In this case, as shown in FIG. 2 (A), the slit is divided into a plurality of parts in the circumferential direction by the slit 22 that coincides with the central axis direction of the rotor cylindrical portion, and as shown in FIG. 2 (B), It is also possible to divide a plurality of parts in the circumferential direction by the slits 23 inclined with respect to the central axis direction of the part. The inclination angle of the slit 23 in this case is not particularly limited, but if the inclination angle is too large, the effect of division will be impaired.

When the slits 22 and 23 are provided by machining using a slitter after forming the coating layer and when forming the coating layer by the electroplating method, a mask corresponding to the slit is provided on the outer cylinder. It may be arranged on the inner peripheral surface of No. 2 and plated by using a so-called masking method to provide slits.

The eddy current type speed reducer shown in FIG. 1 having a rotor in which the coating layer is divided into a plurality of pieces in the circumferential direction and the same eddy current type speed reducer having a rotor in which the coating layer is not divided are used for comparison. As a test condition, braking / non-braking was repeated until the temperature of the rotor cylindrical portion reached 600 ° C., and a durability test was performed. The results are shown in Table 1. The material of the rotor is:
Cr-Mo low alloy steel with a shape of outer diameter: 450 mm, inner diameter of cylinder: 400 mm, width: 75 mm, wall thickness of cylinder: 1
0 mm, cooling fin height: 15 mm, the number of rotations in the test was 1800 rpm for samples 1 to 8 and sample 9
In the case of ~ 16, it is 2800 rpm.

[0027]

[Table 1]

From the results shown in Table 1, when the coating layer was divided into a plurality of pieces in the circumferential direction according to the present invention, the number of revolutions was 1800 rpm and 2800 rpm.
In the case of the comparative example, the rotation speed is 1800 rpm, 280 rpm
In any case of 0 rpm, peeling occurred up to 2500 cycles, which shows that the rotor according to the present invention has excellent durability.

Further, the sample No. When the groove widths of the slits 3, 5, 11, 12 are 1 mm or less and the number of slits is 16 or less, the durability is excellent as compared with the comparative example, and the peak torque value is equal to or more than that. . Therefore, when carrying out the present invention, it is desirable that the slits are installed under conditions of a groove width of 1 mm or less and the number of installed slits is 16 or less.

The above embodiment is an eddy current type speed reducer using a permanent magnet, but the eddy current type speed reducer using an electromagnet instead of the permanent magnet is mechanically the same as the former, and has a rotor cylindrical portion. Also in the same manner as in the above-mentioned embodiment, a plurality of slits extending in the width direction of the rotor cylindrical portion are provided in the circumferential direction to provide a plurality of divided coating layers.

[0031]

According to the present invention, due to continuous use of the eddy current type speed reducer, peeling of the coating layer and thermal cracking can be prevented even if braking / non-braking at which the temperature of the rotor cylindrical portion becomes 600 ° C. or more is repeated. It does not occur, can withstand long-term use, and can maintain stable high braking torque.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an eddy current type speed reducer in which a coating layer is formed on an inner peripheral surface of a rotor cylindrical portion according to an embodiment of the present invention.

FIG. 2 is a perspective view of a rotor cylindrical portion having a coating layer formed on an inner peripheral surface according to an embodiment of the present invention, in which (A) is a plurality of circumferentially divided slits that coincide with a central axis direction of the rotor cylindrical portion. , (B) is a case where a plurality of slits are circumferentially divided by slits inclined with respect to the central axis direction of the rotor cylindrical portion.

FIG. 3 is an explanatory view showing an example of a coating layer formed on an inner peripheral surface of a rotor cylindrical portion.

4A and 4B are explanatory diagrams showing the occurrence of delamination at the Fe-Ni interface due to a diffusion phenomenon at a high temperature. FIG. 4A is a state in which atoms are diffused, and FIG. 4B is a state in which diffusion holes are generated at the Fe-Ni interface.
(C) is a state in which diffusion holes generated at the Fe-Ni interface are combined and grown in a band shape.

[Explanation of symbols]

1 rotor 2 outer cylinder 3 inner cylinder 4 arms 5 cooling fins 6 Mounting disc 7 rod 8 permanent magnets 10 cylinders 11 rotation axis 12 Magnetic shield case 13 Support ring 14 bearings 15 Support plate 16 Support member 17 Guide rod 18 coating layer 19 pole pieces 20 Oxidation resistant metal film 21 Ni-P alloy film 22, 23 slits

Front Page Continuation (72) Inventor Mitsuo Miyahara 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Shozo Suehiro 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Inventor Kenji Imanishi 4-53, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (56) Reference JP-A-5-236732 (JP, A) JP 53-125551 (JP, A) Actual development 4-97473 (JP, U) Actual development 56-174687 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02K 49 / 02,49 / 10

Claims (4)

(57) [Claims] 1. A permanent magnet or electromagnet, which is a combination of a support ring around which a plurality of permanent magnets or electromagnets are provided so that the polarities of a rotor fitted to a rotating shaft and adjacent magnets are opposite to each other, with a required gap. In the eddy current reduction device configured to generate an eddy current inside the rotor cylinder by the magnetic circuit of FIG. 1, a coating layer made of copper is provided on the inner peripheral surface of the rotor cylinder portion facing the magnet,
A rotor for an eddy current type speed reducer characterized in that a plurality of slits extending in the width direction of the rotor cylindrical portion are provided on the coating layer to divide the rotor into a plurality of portions in the circumferential direction. 2. The eddy current reduction gear rotor according to claim 1, wherein an oxidation resistant metal film is formed on the surface of the coating layer divided into a plurality of pieces in the circumferential direction. 3. The rotor for an eddy current type speed reducer according to claim 1, wherein the coating layer is divided into a plurality of portions in the circumferential direction by a large number of slits that coincide with the central axis direction of the rotor cylindrical portion. . 4. The eddy current type speed reducer according to claim 1, wherein the coating layer is divided into a plurality of portions in the circumferential direction by a large number of slits inclined with respect to the central axis direction of the rotor cylindrical portion. rotor.