JPH11308851A - Eddy current type speed reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eddy current type speed reducer superior in durability, which can be used under severe use conditions in which the temperature of the rotor itself reaches about 650 deg.C. SOLUTION: A first layer of a nickel alloy layer 21, a second layer of copper or a copper alloy layer 22 a third layer of a nickel alloy layer 23, and a fourth layer of a nickel layer 24 are successively applied to the face opposing the magnet of a rotor, and in the thicknesses of first, third, and fourth layers t1 ,t2 ,t3 , and t4 , t1 is 1-30 μm, (t3 +t4 ) is 5-50 μm, and (t3 /(t3 +t4 )) is 0.05-0.8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In addition to a foot brake as a main brake and an exhaust brake as an auxiliary brake, a braking device for a large vehicle such as a truck or a bus performs stable deceleration when descending on a long slope or the like, and An eddy current speed reducer is used to prevent burning of the foot brake.

FIG. 1 is a longitudinal sectional view showing an example of an eddy current type speed reducer. 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 stator, 6 is a permanent magnet, 7 is a magnet support ring,
8 is a pole piece, 9 is a piston rod, 10 is a pneumatic device, 11 is a rotating shaft, and 12 is a guide rod.

FIG. 1 shows an example in which a permanent magnet is used as a magnet and an inner peripheral surface 13 of a cylindrical portion 3 is used as a rotating surface of a rotor. A permanent magnet 6 is provided so as to face the inner peripheral surface 13 of the cylindrical portion 3. However, the permanent magnet 6 may be provided on the outer peripheral surface side of the cylindrical portion.

In FIG. 1, although permanent magnets are used as magnets, some magnets use electromagnets.

Japanese Patent Application Laid-Open No. 1-288636 discloses an example in which one side of a disk is used as a rotating surface of a rotor, and an electromagnet is used as a magnet.

In either case, a fixed magnet is provided to face the rotating surface of the rotor, and an eddy current is generated in the rotor by the magnetic flux of the magnet. Hereinafter, an eddy current type reduction gear of the type shown in FIG. 1 will be described.

In FIG. 1, a rotor 1 is provided with a cylindrical portion 3 made of a ferromagnetic material via an arm 2,
2 is attached to one end. Rotor cylindrical part 3
Rotates integrally with the rotating shaft 12.

A magnet support ring 7 constituting the stator 5
A plurality of permanent magnets 6 are disposed around the periphery of the magnet, and a magnet support ring 7 is connected to a piston rod 9 of a pneumatic device 10 provided on the stator 5, and a plurality of guide rods are driven by the pneumatic device 10. It reciprocates in the axial direction of the rotating shaft along 12. The state in which the permanent magnet 6 is inserted to the position of the pole piece 8 by the reciprocating movement, that is, the position where the permanent magnet 6 is magnetically opposed to the inner peripheral surface 13 of the cylindrical portion 3 (the upper state of the illustrated shaft) is in the brake-on state. is there. Conversely, a state in which the permanent magnet 6 is away from the pole piece 7 (a state below the shaft shown) is a brake-off state.

In the brake-on state, the cylindrical portion 3 rotates across the magnetic flux generated from the permanent magnet 6, so that an eddy current flows near the inner peripheral surface 13 of the cylindrical portion 3. A braking torque is generated in the rotor 1 by the interaction between the eddy current and the magnetic flux. The cylindrical portion 3 is heated by Joule heat due to the eddy current, and is cooled by the cooling fin 4 in a brake-off state. Therefore, a thermal cycle is applied to the cylindrical portion 3 by repeatedly turning on and off the brake.

In an eddy current type speed reducer using an electromagnet, the principle of generating a braking torque is the same as that of a permanent magnet. However, when a permanent magnet is used, braking is turned on and off by reciprocating the magnet as described above, whereas when an electromagnet is used, braking is performed by adjusting the current of the electromagnet coil. 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 having low electric resistance (such as aluminum, copper or copper alloy) is provided on a rotating surface of the cylindrical portion of the rotor facing the magnet. An apparatus has been proposed (for example, see Japanese Patent Application Laid-Open No. 1-288636).

[0013] Aluminum is preferable as a surface treatment layer having a light weight and a small electric resistance. However, at the time of braking, the temperature may exceed 600 ° C and may be melted. Further, forming an aluminum layer requires a vacuum deposition apparatus and the like, and the production is complicated. Copper or copper alloys can withstand higher temperatures, but there is a problem in that, due to an increase in temperature, they are oxidized and thinned, and the braking torque is reduced.

As a method for solving this problem, Japanese Patent Application Laid-Open No.
Japanese Patent No. 36732 discloses that a surface treatment layer on a rotating surface is made of nickel.
An eddy current speed reducer coated with three layers of a copper-nickel chrome alloy has been proposed.

[0015] The technique disclosed in this publication is to prevent the copper from being oxidized and reduced in thickness by coating the outermost surface of the cylindrical portion with a nickel-chromium alloy, and to prevent the copper layer and the rotor cylindrical portion from being thermally expanded. The purpose is to reduce the relative displacement by the nickel layer.

Although this nickel chromium alloy layer is formed by low pressure spraying, vacancies remain inevitable and oxidation of the copper layer cannot be prevented. Further, the nickel-chromium alloy film has a problem that cracks are easily generated by a thermal cycle or thermal shock since the hardness is high and the toughness is poor.

Nickel is used as a buffer material between the copper layer and the cylindrical portion. In this configuration, when used for a long time, diffusion from copper to nickel occurs. There is a problem that voids (Kirkendal voids) are generated on the side, and the surface-treated portion peels off and falls off therefrom.

[0018]

In recent years, large vehicles equipped with an eddy current type speed reducer have been increasing, and mounting on trucks and trailers having a larger load capacity than before has been promoted. For this reason, the braking capacity required for the eddy current type reduction gear tends to increase, and the rotating surface temperature of the rotor during braking of the eddy current type reduction gear may reach about 650 ° C., which further increases the durability. There is a demand for an apparatus that is excellent in the above.

It is an object of the present invention that the temperature of the rotor is 650 ° C.
Provides a highly durable eddy current type reduction gear that prevents cracks in the surface protection layer and suppresses peeling of the copper or copper alloy layer from the ferromagnetic cylinder under severe operating conditions. Is to do.

[0020]

The present invention has been studied on the premise that the surface treatment layer of the cylindrical portion of the rotor is formed by a plating method capable of forming a film having a more stable quality than the thermal spraying method. As a result, the following findings were obtained.

(A) Copper or a copper alloy is used for the conductor layer of the surface treatment layer. To prevent oxidation and thinning of the copper layer, the outermost layer is preferably made of nickel plating having excellent oxidation resistance and heat cycle resistance. However, in the case of nickel plating alone, copper diffuses from the copper layer, and in order to prevent this, it is preferable to sandwich a nickel-based alloy layer between the copper layer and the nickel layer.

(B) As a cushioning material between the copper layer and the cylindrical portion,
Nickel plating also has the problem of copper diffusion, so a nickel-based alloy layer is required as a layer for preventing copper diffusion. In this case, two layers of a nickel-based alloy layer for preventing diffusion and nickel for the buffer material are not necessary, and the functions of the diffusion-preventing and buffer material can be satisfied by the nickel-based alloy layer.

(C) The thickness of the nickel alloy layer or nickel layer needs to be within an appropriate range.

Based on the above findings, the gist of the present invention resides in the following (1) to (3).

(1) An eddy current reduction device of a type including a rotor and a magnet fixed and provided opposite to the rotating surface of the rotor, wherein an eddy current is generated in the rotor by the magnetic flux of the magnet. A first layer made of a nickel-based alloy, a second layer made of copper or a copper alloy, a third layer made of a nickel-based alloy, and a fourth layer made of nickel on the rotating surface facing the magnet. An eddy current type reduction gear characterized by being provided sequentially.

(2) The eddy current type speed reducer according to the above (1), wherein the thickness t ₁ of the first layer is in the following range.

[0027] t ₁ = 1 to 30 [mu] m (3) a third layer thickness t ₃ of the fourth thickness of layer t ₄ is the characterized by satisfying the following formula (1) or (2) of 4. The eddy current type speed reducer according to claim 1.

T ₃ + t ₄ = 5 to 50 μm t ₃ / (t ₃ + t ₄ ) = 0.05 to 0.8

[0029]

FIG. 2 is an enlarged sectional view of a portion A of FIG. 1 showing a surface treated layer applied to the rotating surface of the present invention, that is, the inner peripheral surface 13 of FIG. In the figure, a first layer 21 is a buffer layer between the second layer 22 and the cylindrical portion 3. The second layer is a layer having a small electric resistance, and has a function of promoting the generation of an eddy current and increasing a braking force since the electric resistance is smaller than that of the ferromagnetic cylindrical portion. The third and fourth layers are protective layers of the second copper layer. The requirements for the first layer will be described later.

As the material of the second layer 22, copper, copper alloy or aluminum having a small electric resistance can be used, but aluminum cannot be used under the condition that the maximum temperature exceeds 600 ° C. because of its low melting point. Therefore, in the present invention, a layer made of copper or a copper alloy (hereinafter, also collectively referred to as a copper layer) is used.

If the copper layer is excessively thin, eddy current also flows through the cylinder, so that the electric resistance increases, the eddy current decreases, and the braking force decreases. Copper is non-magnetic, and if the copper layer is too thick, the magnetic flux density reaching the cylindrical portion of the ferromagnetic rotor is reduced, so that the braking torque is reduced. Therefore, a preferable value of the thickness of the copper layer is 50 to 400 μm.

The fourth layer 24 is the outermost nickel layer.
Nickel has excellent oxidation resistance in the temperature range of 600 to 700 ° C., and is soft and highly ductile, so that it does not crack easily even when subjected to thermal cycles and thermal shocks. To contribute. However, when nickel of the fourth layer is directly coated on the copper layer of the second layer, diffusion from copper to nickel occurs at the interface, voids (Kirkendale voids) are generated on the copper side, and the nickel layer may peel. There is.

The nickel-based alloy of the third layer is used between the second and fourth layers as an intermediate protective film in order to suppress the formation of vacancies on the copper side of the second layer. Examples of the alloy element of the third layer nickel-based alloy include tungsten, iron, boron, cobalt, and phosphorus. This is because the diffusion rate of copper in these alloys is smaller than that in nickel, and it is difficult for copper atoms to enter the nickel lattice. The content range (% by weight) of each element alone is as follows.

The content of tungsten is preferably 1 to 50%. Below the lower limit, the effect of suppressing copper diffusion is small, and above the upper limit,
Hardness increases, and peeling and cracking easily occur. A more preferable range is 10 to 40%.

The content of iron is preferably 1 to 15%. If it is less than the lower limit, the effect of suppressing copper diffusion is small, and if it exceeds the upper limit, the coefficient of thermal expansion is too small. A more preferred range is 3 to 12%.

The content of boron is preferably 1 to 10%. If it is less than the lower limit, the effect of suppressing copper diffusion is small. A more preferable range is 2 to 6%.

The content of cobalt is preferably 1 to 20%. If the amount is less than the lower limit, the effect of suppressing copper diffusion is small, and if the amount exceeds the upper limit, the cost is increased and disadvantageous. A more preferred range is 5 to 18%.

The content of phosphorus is preferably 1 to 20%. If it is less than the lower limit, the effect of suppressing copper diffusion is small, and if it exceeds the upper limit, the hardness increases and the toughness is poor, so that cracking and peeling are likely to occur. A more preferred range is 5 to 14%.

When these elements are contained in a complex form, the total content is 1% so as not to exceed the upper limit of the single element.
It is preferably about 50%. A more preferable range is 1 to 4.
0%.

The thickness of the third nickel-based alloy layer is t ₃ ,
Assuming that the thickness of the fourth nickel layer is t ₄ , the total thickness (t ₃ + t ₄ ) of the third and fourth layers is in the range of 5 to 50 μm, and (t ₃ / (t ₃ + t ₄ )) ) Is desirably adjusted to be 0.05 to 0.8. Under this layer thickness condition,
In a temperature range up to 650 ° C., vacancies due to diffusion between copper and nickel can be prevented, and cracking of the nickel-based alloy intermediate protective film due to thermal strain or thermal shock can be prevented.

The total thickness of the third and fourth layers (t ₃ + t ₄ ) is 5
If the thickness exceeds 0 μm, the protective effect of the copper layer is saturated and the cost increases. When (t ₃ + t ₄ ) is less than 5 μm, when subjected to a severe thermal cycle at a maximum temperature of about 650 ° C., the effect of preventing the generation of vacancies due to the diffusion of copper and the cracking of the nickel-based alloy protective film The effect of preventing the occurrence of the deficiency becomes insufficient, and there is a possibility that holes are partially generated.

If (t ₃ / (t ₃ + t ₄ )) is less than 0.05, the generation of vacancies due to the diffusion between copper and nickel will occur when a severe thermal cycle of a maximum temperature of about 650 ° C. is applied. In some cases, the effect of prevention is insufficient, and voids may partially occur.

When (t ₃ / (t ₃ + t ₄ )) exceeds 0.8, the thickness of the third nickel layer is excessively large, and the thickness of the protection film of the fourth layer is excessively small, and the maximum temperature is 650 ° C. When subjected to a severe thermal cycle, the third nickel-based alloy layer may be cracked.

A more preferable range is (t ₃ + t ₄ ) = 1.
5 to 50 μm, (t ₃ / (t ₃ + t ₄ )) = 0.1 to
0.6.

The reason why the first layer 21 is provided between the cylindrical portion 3 of the rotor and the copper layer of the second layer 22 is that the ferromagnetic cylindrical portion 3 (generally steel or alloy steel) and the second layer copper This is to buffer the shear stress caused by the difference in the coefficient of thermal expansion between the layer and the layer. The reason why the first layer is a nickel-based alloy layer is to suppress the diffusion of copper while maintaining the buffering effect of the nickel-based alloy. Therefore, it differs from the third nickel-based alloy layer in that it aims at a buffer effect. However, the material may be the same as the material used in the third layer.

In this case, assuming that the thickness of the first layer is t ₁ , t _1
It is desirable that ₁ = _{1 to} 30 μm. Normally, the surface treatment layer is formed by electroplating or electroless plating, which is advantageous in terms of price and quality. However, due to the control of the thickness of the plating layer, t _{1 is set} to less than ₁ μm in order to perform stable film thickness control. Hard to do. If t ₁ is less than ₁ μm, the effect of buffering the thermal stress between the rotor cylindrical portion and the copper layer becomes insufficient.

When t ₁ exceeds 30 μm, the buffer effect is saturated and the cost increases, and furthermore, there is a possibility that a defect occurs in the plating layer and the possibility of destruction therefrom increases. A more preferable range is 2 to 20 μm.

[0048]

EXAMPLE An eddy current type speed reducer shown in FIG. 1 was provided with various surface treatment layers shown in Table 1 on an inner peripheral surface 13 of a cylindrical portion 3 of a rotor.

The nickel alloy plating conditions for the first and third layers of the rotor of the present invention are as shown in Table 1. Second
The copper layer was formed by an electroplating method using a cyan copper plating bath. The temperature of the plating bath was 50 ° C., and the current density was 2.5 A / dm ² . The purity of the formed plating layer was 99.9% by weight or more. The fourth nickel plating layer was formed by an electroplating method using a Watt bath. The temperature of the plating bath is 50 ° C., and the current density is 1.5 A /
dm ² . The purity of the formed plating layer is 99.9.
% By weight or more.

As a comparative example, a test piece without a first nickel-based alloy layer, a test piece without a nickel layer, and a test piece without a third nickel alloy layer were used. However, the layer numbers of the comparative examples are shown in Tables 1 and 2 according to the corresponding layers of the present invention examples.
It was noted in.

[0051]

[Table 1]

These rotor specimens were mounted in the middle of the propeller shaft at the rear of the transmission of the heavy-duty truck, and the braking torque was measured and the braking test for investigating the durability was carried out. The eddy current speed reducer used for the test was for a 10-ton vehicle, and the cylindrical part of the rotor was Cr-
It is made of Mo type low alloy steel, and the inner diameter of the cylindrical portion 3 is about 400.
mm, the thickness was about 10 mm, and the axial length was about 80 mm.

In measuring the braking torque, first, FIG.
The rotation speed of the rotation shaft 11 was gradually increased, and the braking torque at the time when the rotation speed became 1000 rpm and 2000 rpm was measured.

In the repetitive braking test, the rotation speed of the propeller shaft was kept constant at 2000 rpm, and the brake was repeatedly turned on and off to repeatedly apply temperature fluctuations to the rotor. The braking on and off times at this time were adjusted so that the maximum temperature of the inner peripheral surface of the rotor was about 650 ° C and the minimum temperature was about 100 ° C. This braking and non-braking
000 cycles were repeated, and the state of damage on the inner surface of the cylindrical portion of the rotor after the test was observed. Furthermore, a micro-investigation of the rotor cross section after the test was performed to investigate the damage state of the surface treatment layer.
Table 2 shows the test results.

[0055]

[Table 2]

From the test results in Table 2, it was found that the braking torque was hardly affected by the presence or absence of the first, third and fourth layers of nickel or nickel alloy.

The test piece No. of the present invention example. In Nos. 1 to 17, swelling was observed in a part of the surface treatment layer, but no separation was observed at the interface between the rotor cylindrical portion and the surface treatment layer, and the surface was not cracked. there were. All the samples having the thickness of the plating layer within the specified range of the present invention were good.

The test piece No. of the comparative example. 18-20 are the first
This is a test piece having no nickel alloy plating layer. 2nd
Swelling was observed in the four surface treatment layers, and some of them were dropped off.

The test piece No. of the comparative example. Reference numeral 21 denotes a specimen in which the first layer is nickel-plated and the conditions of the third and fourth layers are the same as those of the present invention. Swelling was observed in the second to fourth surface treatment layers, and some of them were dropped off.

The test piece No. of Comparative Example Reference numeral 22 denotes a test body in which the conditions of the first layer are the same as those of the present invention, and the fourth layer is nickel-plated directly on the second layer copper layer without the third layer nickel alloy plating layer. Small cracks were observed on the nickel plating surface of the fourth layer, and some voids were found at the interface between the second layer and the third layer.

[0061]

The rotor for the eddy current type reduction gear of the present invention is
Compared to conventional eddy current type reduction gear rotors, the surface treatment layer provided to improve braking torque has excellent durability, and stable braking force can be obtained even when used at high temperatures for a long time. The safety of large vehicles such as trucks and trailers is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an eddy current type speed reducer using a permanent magnet.

FIG. 2 is an enlarged sectional view showing a surface treatment layer applied to the surface of the rotating surface of the rotor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 2 Arm 3 Cylindrical part 4 Cooling fin 5 Stator 6 Permanent magnet 7 Magnet support ring 8 Pole piece 9 Piston rod 10 Pneumatic device 11 Rotary shaft 12 Guide rod 13 Inner peripheral surface 21 First layer 22 Second layer 23 First 3rd layer 24 4th layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoka Ishida 5-1-1109, Shimaya, Konohana-ku, Osaka Sumitomo Metal Industries, Ltd. Kansai Works Steelmaking Works (72) Inventor Katsuhiko Akasaki Konohana-ku, Osaka-shi 5-1-1 Shimaya Sumitomo Metal Industries Co., Ltd. Kansai Works Steelmaking Works (72) Inventor Kunihiro Fukui 4-5-33 Kitahama, Chuo-ku, Osaka City Sumitomo Metal Industries Co., Ltd.

Claims (3)

[Claims] 1. An eddy current reduction device of a type comprising a rotor and a magnet fixed to and opposed to a rotating surface of the rotor, wherein an eddy current is generated in the rotor by a magnetic flux of the magnet. A first layer made of a nickel-based alloy, a second layer made of copper or a copper alloy, a third layer made of a nickel-based alloy, and a fourth layer made of nickel are sequentially formed on the rotating surface facing the magnet. An eddy current type reduction gear characterized by being provided. 2. The eddy current type reduction gear according to claim 1, wherein the thickness t ₁ of the first layer is in the following range. t ₁ = _{1 to} 30 μm 3. The thickness t ₃ of the third layer and the thickness t of the fourth layer
3. The eddy current type speed reducer according to claim 1, wherein ₄ satisfies the following expression. t ₃ + t ₄ = 5 to 50 μm t ₃ / (t ₃ + t ₄ ) = 0.05 to 0.8