JP3473298B2 - 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 of an eddy current type speed reducer installed in a large automobile such as a truck or a bus.

[0002]

2. Description of the Related Art In addition to a foot brake which is a main brake and an exhaust brake which is an auxiliary brake, a braking device for a large automobile such as a truck or a bus is capable of performing stable deceleration even on a long downhill and the like. An eddy current type speed reducer is used to prevent the burnout. This eddy current type speed reducer includes one using a permanent magnet as a magnet and one using an electromagnet.

Several examples have already been proposed for the structure of the eddy current type speed reducer (for example, Japanese Patent Laid-Open No. 1-23).
4043, JP 1-234045, JP 1-298948, etc.).

FIG. 1 is a vertical sectional view showing an example of an eddy current type speed reducer using a permanent magnet and a partial enlargement of a rotor cylindrical portion. In the figure, reference numeral 1 is a rotor, 2 is an arm of the rotor, 3 is a cylindrical portion of the rotor, 4 is a cooling fin, 5
Is a permanent magnet, 6 is a magnet support ring, 7 is a pole piece, 8 is a piston rod, 9 is a hydraulic device, 10 is a rotating shaft,
11 is a guide rod.

A cylindrical portion 3 made of a ferromagnetic material is arranged in the rotor 1 via an arm 2 of the rotor, and is attached to one end of the rotary shaft 10. Cylindrical part of rotor 3
Rotates integrally with the rotating shaft 10. A plurality of permanent magnets 5 are provided around a magnet supporting ring 6, and the magnet supporting ring 6 is screwed to a piston rod 8 of a hydraulic device 9 and driven by the hydraulic device 9 to rotate along a plurality of guide rods 11. Reciprocates in the axial direction. By this reciprocating motion, the state where the permanent magnet 5 is inserted to the position of the pole piece 7, that is, the position where it is magnetically opposed to the cylindrical portion 3 of the rotor (the upper state in the figure) is the braking on state. On the contrary, the state in which the permanent magnet 5 is away from the pole piece 7 (the lower state in the figure) is the braking off state.

In the braking ON state, the cylindrical portion 3 of the rotor makes a rotational movement across the magnetic flux generated from the permanent magnet 5, so that an eddy current flows near the inner wall surface of the cylindrical portion. A braking torque is generated in the rotor due to the interaction between the eddy current and the magnetic flux. This cylindrical portion is heated by the Joule heat associated with the eddy current, and is cooled by the cooling fin 4 in the braking off state. Therefore, a thermal cycle is applied to the cylindrical portion 3 of the rotor by repeating on / off of braking.

In the eddy current type speed reducer using the electromagnet, the principle of generating the braking torque is the same as that of the permanent magnet. However, when a permanent magnet is used, braking is turned on and off by reciprocating motion of the magnet as described above, whereas when an electromagnet is used, braking is performed by adjusting the current of the electromagnet coil. Turn on and off.

As a method of increasing the braking torque, an eddy current type deceleration in which a surface treatment layer made of a material (aluminum, copper or copper alloy) having a small electric resistance is provided on the inner wall surface facing the magnet of the cylindrical portion of the rotor. An apparatus has been proposed (for example, JP-A-63-274359 and JP-A-64-304).
(See Japanese Patent Laid-Open No. 50886/1989 and Japanese Patent Laid-Open No. 1-288636). Aluminum is lightweight and has low electric resistance and is preferable as a surface treatment layer, but the temperature may exceed 600 ° C. during braking.
May melt. Further, in order to form the aluminum layer, a vacuum vapor deposition device or the like is required, and the production is complicated.
Copper or a copper alloy has a problem that the braking torque is reduced due to oxidation and thickness reduction due to temperature increase during braking.

As a method for solving this, an example of an eddy current type speed reducer in which the surface treatment layer on the inner wall of the cylindrical portion of the rotor is coated with a plurality of layers of nickel-copper-nickel is proposed (Japanese Patent Laid-Open No. 1-288636). See the bulletin). This is because the coating of nickel prevents the copper or copper alloy from being oxidized and thinned due to the temperature rise during braking, and the braking torque being reduced. However, nickel is oxidatively worn at a high temperature of 600 ° C., and cracks easily occur due to thermal cycling, so that copper or a copper alloy is exposed and the braking force is reduced.

In order to solve this, it has been proposed to provide a nickel-chromium alloy film as a protective film of copper or copper alloy (see Japanese Patent Laid-Open No. 5-236732). This alloy film is supposed to be formed by reduced pressure spraying, but even with this method, it is unavoidable that voids remain and the oxidation of copper or copper alloy cannot be prevented. Further, since the nickel-chromium alloy film has high hardness, it has poor toughness, and cracks are likely to occur due to thermal cycling or thermal shock.

[0011]

In recent years, the load capacity of large automobiles has increased, and the braking capacity required for eddy current type speed reducers has tended to increase. Therefore, the temperature during braking may be about 650 ° C., and a device having more excellent durability is desired for use under such severe conditions.

An object of the present invention is to provide a rotor for an eddy current type speed reducer, which has excellent durability under such severe use conditions.

[0013]

Means for Solving the Problems The present inventors have conducted research on the assumption that a protective film of copper or a copper alloy is formed by a plating method, and a copper or copper alloy surface treatment layer is directly applied to a cylindrical portion of a rotor. It was confirmed that a rotor for an eddy current type speed reducer with excellent durability can be obtained even when a temperature of over 600 ° C is reached by providing a nickel-based alloy on top of this and coating nickel on it. The present invention has been completed.

The gist of the present invention is a rotor for an eddy current type speed reducer shown below (see FIG. 1).

A rotary shaft 10 having a cylindrical portion 3 made of a ferromagnetic material.
A rotor 1 connected to the rotor 1 and a support ring 6 around which a plurality of magnets 5 are circumferentially arranged and which does not rotate are arranged at a position facing the inner wall surface of the cylindrical portion at a predetermined interval. A rotor of an eddy current type speed reducer configured to generate an electric current, wherein a surface treatment layer 31 made of copper or a copper alloy is provided on an inner wall surface portion of a cylindrical portion 3 of the rotor, and a nickel-based alloy is provided thereon. Intermediate protective film 32 consisting of
However, the rotor for an eddy current type speed reducer further having an upper protective film 33 made of nickel provided thereon.

A rotary shaft 10 having a cylindrical portion 3 made of a ferromagnetic material.
A rotor 1 connected to the rotor 1, and a support ring 6 around which a plurality of magnets 5 are circumferentially arranged and which does not rotate are arranged at a position facing the inner wall surface of the cylindrical portion at a predetermined interval. A rotor of an eddy current type speed reducer configured to generate an electric current, wherein a surface treatment layer 31 made of copper or a copper alloy is provided on an inner wall surface portion of a cylindrical portion 3 of the rotor, and a nickel-based alloy thereon. Intermediate protective film 32 consisting of
Is a rotor for an eddy current type speed reducer characterized in that an upper protective film 33 made of nickel is further provided thereon , wherein the nickel alloy is tungsten, iron,
Contains one or more selected from boron, cobalt and phosphorus
An eddy current type speed reducer rotor characterized in that

T ₁ / (t ₁ + t ₂ ) = 0.05 to 0.8 (1) t ₁ + t ₂ = 5 to 50 μm (2) Surface treatment made of copper or copper alloy The layer, the intermediate protective film made of a nickel-based alloy, and the upper protective film made of nickel are formed by an electroplating method or an electroless plating method. Examples of alloying elements of the copper alloy include zinc and tin. As the alloy element of the nickel-based alloy, one kind selected from tungsten, iron, boron, cobalt and phosphorus
The above is used. Then, in the nickel-based alloy, the content of alloy elements other than nickel is preferably 1 to 30 wt%. When the nickel-based alloy contains a plurality of alloy elements other than nickel, the content of the alloy elements other than nickel is defined by the total amount of the alloy elements.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The reason why a protective film for a surface treatment layer made of copper or a copper alloy is a double film of a nickel-based alloy protective film and a nickel protective film will be described.

The surface treatment layer made of copper or a copper alloy as the first layer promotes the generation of eddy current and increases the braking force. In the present invention, the braking force is further increased by directly providing this surface treatment layer on the cylindrical portion of the rotor. The thickness of the surface treatment layer made of the copper or copper alloy is
It is desirable that the thickness be 500 μm or less.

Nickel is used as the upper protective film because nickel has excellent oxidation resistance in the temperature range of 600 to 700 ° C. and is soft and rich in ductility, so that it is resistant to thermal cycles and thermal shock. This is because there are few cracks. However, when nickel is directly plated on copper or a copper alloy, diffusion occurs from copper to nickel at the plating interface, and voids (Kirkendal voids) are formed on the copper side, and the nickel plating layer is peeled off. The nickel-based alloy is used as an intermediate protective film in order to suppress the formation of the above-mentioned voids on the copper side. As the alloying element of the nickel-based alloy, one or more selected from tungsten, iron, boron, cobalt and phosphorus.
The above is used. The content of alloying elements other than nickel in the nickel-based alloy is preferably 1 to 30% by weight,
15% by weight is more preferred. Nickel-based alloys are superior to nickel in oxidation resistance, hard, and have excellent adhesion strength. However, since it is hard, it is similar to the case of the nickel-chromium alloy described above, and cracks are likely to occur due to thermal cycling or thermal shock. Therefore, in the present invention, a plating layer made of a nickel-based alloy is formed as an intermediate protective film on the copper or copper alloy surface treatment layer, and an upper protective film made of a nickel plating layer is further provided thereon.

FIG. 1 is an enlarged view of a portion A showing a longitudinal section of the cylindrical portion of the rotor for an eddy current type speed reducer of the present invention. In the figure, the intermediate protective film 32 of nickel-based alloy is in contact with the copper or copper alloy surface treatment layer 31. That is, copper or copper alloy does not directly contact the upper protective film 33 of nickel. Therefore, it is difficult to form an alloy with nickel, and voids due to diffusion do not occur. Furthermore, since the surface of the nickel-based alloy protective film is covered with the soft nickel protective film, cracks are unlikely to occur on the surface even when subjected to a thermal cycle or thermal shock.

Next, the desired thickness of the protective film will be described.

The thickness of the nickel-based alloy intermediate protective film is t ₁ ,
When the thickness of the nickel upper protective film is t ₂ , t ₁ / (t ₁
+ t ₂ ) is 0.05 to 0.8, and the thickness of the protective film (t ₁ + t ₂ ) is 5
If adjusted to be in the range of up to 50 μm, it is possible to prevent the formation of vacancies due to diffusion between copper and nickel in the temperature range up to 650 ° C, and to protect the intermediate protective film of nickel-based alloy due to thermal strain or thermal shock. Can prevent cracks.

The thickness of the nickel-based alloy protective film is thin and t ₁ /
If (t ₁ + t ₂ ) is less than 0.05, the effect of preventing the generation of vacancies due to diffusion between copper and nickel is insufficient when subjected to a severe thermal cycle with a maximum temperature of about 650 ° C. Occasionally, holes may occur. Therefore, t ₁ / (t ₁ + t ₂ ) is 0.05
The above is desirable.

The thickness of the nickel-based alloy protective film is large, t ₁ /
If (t ₁ + t ₂ ) exceeds 0.8, the thickness of the nickel protective film becomes thin, and it is effective in preventing cracks in the nickel-based alloy protective film when subjected to a severe thermal cycle with a maximum temperature of about 650 ° C. It may be insufficient and may partially crack. Therefore, it is desirable that t ₁ / (t ₁ + t ₂ ) is 0.8 or less.

Next, when the thickness (t ₁ + t ₂ ) of the protective film is less than 5 μm, when a maximum temperature of about 650 ° C. is subjected to a severe thermal cycle, voids are generated due to diffusion between copper and nickel. The effect of preventing and the effect of preventing cracking of the nickel-based alloy protective film become insufficient, and voids may be partially formed. When the thickness (t ₁ + t ₂ ) of the protective film exceeds 50 μm, the protective effect is saturated, which is economically disadvantageous. Therefore, (t ₁
The thickness of + t ₂ ) is preferably 5 to 50 μm.

The rotor of the present invention can be applied to any permanent magnet type or electromagnet type eddy current type speed reducer.

[0028]

EXAMPLE A copper surface treatment layer 31, as shown in Table 1, on the inner wall surface of the cylindrical portion 3 of the rotor of the eddy current type speed reducer shown in FIG.
Both the intermediate protective film 32 of nickel alloy and the upper protective film 33 of nickel were coated by a plating method to prepare a test body. An eddy current type speed reducer equipped with these test bodies was installed in the middle of a propeller shaft at the rear of the transmission of a heavy-duty truck to measure braking torque and carry out a repeated braking test to investigate durability. The eddy current type speed reducer used in the test is for 10-ton vehicles, and the cylindrical part of the rotor is made of Cr-Mo low alloy steel (JIS SC
The inner diameter of the cylindrical portion 3 was about 380 mm, the wall thickness was about 20 mm, and the axial length was about 80 mm.

The surface treatment layer made of copper was formed by electroplating using a cyan copper plating bath. At this time, the temperature of the plating bath was 50 ° C. and the current density was 3 A / dm ² .
The formed plating layer contained 99.9% by weight or more of copper and had a thickness of 100 μm or 200 μm. The composition and plating conditions of the nickel-based alloy intermediate protective film are shown in Table 1. The nickel-chromium alloy protective film of the comparative example was formed by reduced pressure spraying. The upper nickel protective film was formed by electroplating using a Watt bath. At this time, the temperature of the plating bath was 50 ° C. and the current density was 5 A / dm ² . The formed plating layer contains 99.9% by weight or more of nickel, and the thickness is shown in Table 1. In addition, for comparison, a film not coated with the intermediate protective film or the upper protective film was prepared.

[0030]

[Table 1]

The thickness and hardness of the protective film were measured by an electromagnetic film thickness meter and a micro Vickers hardness meter. To measure the braking torque, first measure the propeller shaft (rotating shaft in Fig. 1).
Braking torque was measured by turning on braking at rotational speeds of the shaft (connecting 10) of 1000 rpm and 2000 rpm. In the repeated braking test, the propeller shaft rotation speed was set to 2000 rpm, then the braking was turned on, and when the surface of the inner wall of the cylindrical part of the rotor reached about 650 ° C, the braking was turned off.
After cooling to 100 ° C., a repeated test was performed in which braking was turned on again. This repetition was repeated 2000 times, and the inner wall surface of the cylindrical portion of the rotor after the test was observed. The results are shown in Table 1.
And shown in Table 2.

[0032]

[Table 2]

From Tables 1 and 2, the braking torque increases as the thickness of the copper surface treatment layer increases, but the braking torque is not significantly affected by the presence or absence of the protective film, that is, there is not much difference from the comparative example. Recognize. However, in the test samples (No. 1 to 15) of the invention example in which the intermediate protective film of nickel alloy and the upper protective film of nickel were provided on the copper surface treatment layer, almost no oxidation was observed in the copper surface treatment layer. No, it is good. Furthermore, in the test bodies (Nos. 5 to 15) in which the thickness of the protective film was adjusted, cracks in the intermediate protective film and generation of voids at the interface of the copper surface treatment layer were not observed.

On the other hand, the test body of the comparative example (No. 16, 1
In 7), it was observed that the copper surface treatment layer was oxidized to black because no protective film was provided. Specimen (No.18)
Coats a nickel-chromium alloy by vacuum spraying,
Since the upper protective film for nickel was not provided, nickel-
Cracks occurred in the chromium alloy layer, and swelling due to oxidation occurred in the copper surface treatment layer at the cracked portion. The test piece (No. 19) is
Since only the nickel protective film was provided, oxidation was observed in the Cu surface treatment layer, voids were observed at the interface with the protective film, and the protective film in the void portion was peeled off.

Since the test bodies (No. 20 to 22) were provided with only the intermediate protective film of nickel alloy, oxidation was observed in the copper surface treatment layer, cracks were generated in the intermediate protective film, and the copper surface of the cracked portion was observed. Swelling due to oxidation occurred in the treated layer.

[0036]

In the rotor for an eddy current type speed reducer of the present invention, since the intermediate protective film of nickel alloy and the upper protective film of nickel are doubly provided on the copper or copper alloy layer, an automobile having a large carrying weight is provided. It has excellent durability even after repeated braking under severe conditions, and provides stable braking force even during long-term deceleration.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of an eddy current type speed reducer using a permanent magnet and a partial enlargement of a rotor cylindrical portion.

[Explanation of symbols]

1. Rotor 2. Rotor arm 3. Cylindrical part of rotor 4. Cooling fins 5. Permanent magnet 6. Magnet support ring 7. Pole piece 8. Piston rod 9. Hydraulic system 10. Axis of rotation 11. Guide bar

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Akasaki 5-1109 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. Kansai Works Steel Works (72) Inventor Kunihiro Fukui Osaka City, Osaka Prefecture 4-5-3 Kitahama, Chuo-ku, Sumitomo Metal Industries Co., Ltd. (56) Reference JP-A-5-236732 (JP, A) JP-B 60-38221 (JP, B2) (58) Fields investigated (Int .Cl. ⁷ , DB name) H02K 49 / 02,49 / 10 C25D 5/14

Claims (4)

(57) [Claims] 1. A rotor which has a cylindrical portion made of a ferromagnetic material and which is connected to a rotating shaft, and a plurality of magnets which are circumferentially provided at a position facing the inner wall surface of the cylindrical portion at a predetermined interval so as not to rotate. A rotor of an eddy current type speed reducer having a ring arranged to generate an eddy current in the cylindrical portion by a magnetic flux of a magnet, the inner wall surface portion of the cylindrical portion of the rotor being a surface made of copper or copper alloy. A rotor for an eddy current type speed reducer characterized in that a treatment layer is provided, an intermediate protective film made of a nickel-based alloy thereon, and an upper protective film made of nickel is further provided thereon. Nicke
Alloys include tungsten, iron, boron, cobalt and
Characterized by containing at least one selected from phosphorus
Eddy current type speed reducer rotor . 2. The rotor for an eddy current type speed reducer according to claim 1, wherein the nickel-based alloy contains 1 to 30% by weight of an alloy component other than nickel. 3. The rotor for an eddy current type speed reducer according to claim 1, wherein the intermediate protective film made of a nickel-based alloy is a plating film. 4. The thickness of an intermediate protective film made of a nickel alloy.
t ₁ and the thickness t _{2 of the} upper protective film made of nickel are as follows (1)
The expression (1) is satisfied, and the expression (2) is satisfied .
The rotor for an eddy current type speed reducer according to any one of 1 to 3 . t ₁ / (t ₁ + t ₂ ) = 0.05 to 0.8 ・ ・ ・ ・ (1) t ₁ + t ₂ = 5 to 50 μm ・ ・ ・ ・ (2)