JPH10178771A - Braking drum in eddy current type speed reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to prevent physical properties, such as electric resistance and permeability, from abruptly varying at joint, to reduce the electric resistance of eddy current as a whole and to obtain a stable high braking torque, even at high temperature when a copper layer is formed on the inside surface of a braking drum, made of iron or iron alloy by mildly varying the composition of the joints. SOLUTION: In the case the material of a braking drum 13 is composed mainly of iron, the end face of the braking drum 13 is clad with a nickel layer with a thickness of 0.5-2mm by welding, and the surface of the nickel layer is clad with a copper layer 35 of a desired thickness by welding. An alloy layer which contains 40-60% of a base metal and the base metal content of which is gradually toward the center of the nickel layer, is placed in the boundary between the iron layer, the base metal of the end face of the braking drum 13 and the nickel layer and in the boundary between the copper layer 35 as the base metal and the nickel layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current reduction device for assisting a friction brake of a large vehicle, and more particularly to a braking drum of an eddy current reduction device for enhancing a braking capability.

[0002]

2. Description of the Related Art In an electromagnet type eddy current reduction device disclosed in Japanese Patent Application Laid-Open No. 63-274,357, an immovable magnet support for supporting a large number of electromagnets is provided between a pair of braking disks connected to a rotating shaft. A metal layer having high conductivity is adhered to an inner surface of the braking disk facing the electromagnet. In the above-described eddy current reduction device, a braking force based on the eddy current is generated in the braking disk by the relative rotation between the braking disk and the electromagnet.

The permanent magnet type eddy current reduction device disclosed in Japanese Patent Application Laid-Open No. 4-88,867 also generates a braking force based on the eddy current on the braking drum by the relative rotation between the braking drum and the permanent magnet. In the eddy current type reduction gear, by combining the material of the braking drum with the iron material and the copper material, the eddy current generated inside the braking drum is increased, and the braking ability can be increased as compared with the case of using only the iron material.

[0004] As means for joining a copper material to an iron material or an iron-based alloy material (such as SCM415), a method in which a thin cylinder made of copper is press-fitted or joined by bolts to a braking drum made of iron or an iron alloy; Alternatively, there is an iron alloy material and a copper material which are directly joined by brazing or welding.
The former method makes it difficult to adhere iron or iron alloy material to copper material,
In the latter method of directly brazing iron or iron alloy material and copper material, the wax melts at a high temperature, the joining strength is extremely reduced, and the minute gaps also reduce the eddy current required for generating the braking torque. Large electrical resistance. In addition, it is difficult to directly join iron or iron alloy with copper by means of welding copper with iron or iron alloy because copper is hardly dissolved in iron or iron alloy, and even if joined, the thermal expansion coefficient of iron or iron alloy and copper Cracks and delaminations occur at the joint at high temperatures. Furthermore, since there is a large difference in the electrical resistivity between the iron or iron alloy material and the copper material, it causes electric corrosion, and the uneven current density causes local heat generation.

In the method of joining an iron or iron alloy material and a copper material disclosed in Japanese Patent Publication No. 87568/1993, a heat-resistant steel material such as SCH22 and a copper material having a high thermal conductivity are rejoined by a nickel solder. However, the brazing temperature of nickel brazing is 925-1200 ° C., and particularly the brazing temperature of brazing material corresponding to B-Ni-2 is 1010-1175 ° C. Since the melting point of copper is 1083 ° C., an alloy layer is formed between copper and nickel, but the composition of the alloy layer is in a range of copper up to 35%. On the other hand, since the melting point of iron is 1534 ° C. and the melting point of nickel is 1455 ° C., the above-mentioned brazing temperature (101
(0-1175 ° C.), no melting reaction takes place between iron and nickel, or even a very small part of the surface.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to reduce the composition of a boundary layer or a joint when a copper layer is formed on the inner peripheral surface of a braking drum made of iron or an iron alloy. By suppressing the sudden change in physical properties such as electrical resistance and magnetic permeability in the boundary layer or the junction,
It is an object of the present invention to provide a braking drum of an eddy current type reduction gear that reduces the electric resistance of eddy current as a whole and enables stable high braking torque to be obtained even at high temperatures.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a brake drum mainly composed of iron, which is connected to a rotating shaft, and a magnet made of a magnetic material disposed inside the brake drum. In an eddy current reduction device having a support cylinder and a number of magnets coupled to the magnet support cylinder so as to face the inner peripheral surface of the braking drum, an end face of the iron-based braking drum has a thickness of 0 mm. A nickel layer of 0.5 to 2 mm was build-up welded, and a copper layer was build-up welded on the surface of the nickel layer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a material such as copper or aluminum having high thermal conductivity and electrical conductivity is applied to the inner peripheral portion of the braking drum, and a material such as iron or iron alloy having a high magnetic permeability is applied to the outer peripheral portion of the braking drum. In each case to achieve an improvement in braking torque. By combining iron or an iron-based alloy with copper as the material of the braking drum, it is possible to optimize the eddy current circuit, but directly joining the iron or iron-based alloy with the copper Doing so has the disadvantages described above at high temperatures.

According to the present invention, a stable and high braking torque can be obtained at a high temperature (400 ° C. or higher) by joining a copper material to an end surface of a braking drum made of iron or an iron alloy using a nickel layer as a buffer layer. Durability and reliability are improved. In other words, when joining iron or iron-based alloy material and copper material,
In order to maintain practical bonding strength even at high temperatures, a nickel layer is interposed as an intermediate layer between iron or an iron-based alloy material and a copper material. TIG, MI is used for joining the iron or iron-based alloy material and the copper material using the nickel layer as an intermediate layer.
This is realized by building up the nickel layer by ordinary welding such as G.

[0010] In brazing and welding, the thickness of the alloy layer formed differs greatly. Basically, the brazing is performed by melting and adding a metal or an alloy (brazing) having a lower melting point than two metal base materials (iron and nickel) to be joined. Thus, the braze diffuses slightly into the base metal, or the braze only forms a thin alloy layer. In order to actively generate an alloy layer and use the change in the composition of the alloy layer, at least heat the metal base material (iron and copper) to be joined to a temperature higher than the melting point of the metal base material. There must be.

In other words, the brazing should not affect the surfaces of the metal base materials to be joined together as much as possible.
In contrast to welding and diffusion that are as small as possible, welding is to actively form an alloy layer by melting metal base materials to be joined together. Accordingly, while the alloy layer formed by brazing is thin and the joining strength is low, the alloy layer formed by welding is thick and the composition of the alloy layer also changes gradually in the thickness direction (see FIG. 1). ), The bonding strength is high.

However, if the nickel layer or the nickel alloy layer is too thick, the braking torque is reduced, and if the nickel layer or the nickel alloy layer is too thin, sufficient bonding strength cannot be obtained. There is an optimum value for the thickness of the nickel layer or the nickel alloy layer. The thickness of the nickel layer or the nickel alloy layer is preferably 0.5 to 2 mm, and the optimum thickness is about 1 mm. However, the nickel layer also includes an alloy layer, and the composition of the nickel layer is such that 50% of the nickel layer is inclinedly changed in the thickness direction of the nickel layer.

[0013]

1 is a front sectional view of a magnet type eddy current reduction device to which the present invention is applied, and FIG. 2 is a side sectional view of the same. In the magnetic eddy current reduction device according to the present invention, the braking drum 13 is connected to the rotating shaft 4. For this reason, the mounting flange 5 having the spline hole 5a is fitted to the output rotary shaft 4 which is supported by the bearing 3 on the end wall of the gear box 2 of the transmission and protrudes from the end wall, and the nut 6 does not come off. Is concluded. The end wall of the brake drum 7 of the parking brake and the flange 9a integral with the boss 9 of the brake drum 13 of the eddy current reduction device are superimposed on the mounting flange 5, and a plurality of bolts 1 are provided.
0 and the nut 10a.

The braking drum 13 is made of a material such as iron or iron alloy as described later, and has a thin conductive layer or copper layer 35 of copper or the like joined to the inner peripheral surface. The braking drum 13 has a base end formed with a number of spokes 12 extending radially from the boss 9.
Is combined with A large number of cooling fins 13a are integrally provided on the outer peripheral wall of the braking drum 13 at equal intervals in the circumferential direction.

A guide cylinder 18 having a box-shaped inner space is coaxially arranged inside the braking drum 13. The stationary guide cylinder 18 made of a non-magnetic material is fixed to a frame plate 31 externally fitted and fixed to the protruding wall 2a of the gear box 2 by bolts 32, 32a. The guide tube 18 may be formed by connecting an annular end wall plate to both ends of an outer peripheral wall portion 18a and an inner peripheral wall portion 18b, but the illustrated guide tube 18 has a left half portion made of a magnetic material such as iron. A cylindrical portion having a U-shaped cross section and a cylindrical portion having an inverted L-shaped cross section in the right half made of a non-magnetic material such as aluminum are connected by a number of bolts 14.

A large number of openings are provided in the outer peripheral wall portion 18a of the guide cylinder 18 facing the inner peripheral surface of the braking drum 13 at equal circumferential intervals, and a ferromagnetic plate (pole piece) 21 is fitted and fixed in each opening. Is done. In practice, the ferromagnetic plate 21 is
a is cast when aluminum is cast from aluminum.

A plurality of actuators (not shown) are supported on the frame plate 31 having the reinforcing ribs 31a at equal intervals in the circumferential direction. The actuator has a piston fitted into the cylinder to define a pair of fluid pressure chambers, and a magnet support cylinder 19 is connected to an end of a rod 17 projecting from the piston into the inner space of the guide cylinder 18. The magnet support cylinder 19 is supported by the inner space of the guide cylinder 18 so as to be movable in the axial direction. On the outer peripheral wall of the magnet support cylinder 19,
The magnets 20 facing each ferromagnetic plate 21 are coupled such that the polarities are alternately different in the circumferential direction.

At the time of braking, as shown in FIG. 1, the magnet supporting cylinder 19 is moved by the rod 17 of the actuator to the braking drum 13 as shown in FIG.
Is protruded into the inside of. The rotating braking drum 13 is a magnet 2
When crossing the magnetic field from 0 to the inner peripheral surface of the braking drum 13 through the ferromagnetic plate 21, an eddy current is generated in the braking drum 13,
The braking drum 13 generates a braking torque. Brake drum 1
3 generates heat by the eddy current and directly or by cooling fins 13a.
Is cooled by the outside air. At this time, as shown in FIG. 2, a magnetic circuit 40 is formed between the magnet support cylinder 19 and the braking drum 13. At the time of non-braking, the actuator moves the magnet support cylinder 19 to the left in FIG.
, The magnet 20 stops applying a magnetic field to the braking drum 13, and the braking drum 13 does not generate a braking torque. As described above, the magnet type eddy current reduction device is
And a braking force based on the eddy current generated by the relative rotation of the braking drum 13, the greater the eddy current and the magnetic field, the greater the braking torque.

As shown in FIG. 3, the present invention relates to a brake drum 1.
In order to increase the braking torque of the brake drum 3, the outer peripheral portion, that is, the main body portion of the brake drum 13 is made of a material having a high magnetic permeability such as iron or iron alloy to increase the magnetic flux density, and the eddy current is generated at the brake drum 13 A copper layer 35 having a large electric conductivity is provided on an inner peripheral portion of the copper layer 13 through a nickel layer 34 by a method described later.
To increase the eddy current.

As shown in FIGS. 4 and 5, the copper layer 35 may be provided not only on the entire inner peripheral portion of the braking drum 13 but also on one or both ends of the inner peripheral portion of the braking drum 13. Further, as shown in FIGS. 6 and 7, a copper layer 35 may be joined to the entire surface of one end surface or both end surfaces of the braking drum 13.

In the embodiment shown in FIGS.
3 is extended to cover the outer peripheral portion of the braking drum 13, and a copper body 35 a covering the outer peripheral portion is further provided with an annular cooling fin 35 b projecting radially outward. Are integrally formed. In other words, the annular groove 38 on the inner surface of the copper annular body having a reverse L-shaped or inverted U-shaped cross section having a plurality of cooling fins 35b,
A cylinder (brake drum main body) made of iron or an iron alloy is joined. Since the cooling fin 35b is formed integrally with the copper layer 35 having a large electric conductivity and thermal conductivity, heat generated by the eddy current generated in the copper layer 35 is transmitted to the cooling fin 35b, and the efficiency is improved by the outside air around the cooling fin 35b. Is cooled down. 4 to 9, illustration of a bonding layer between the main body of the braking drum 13 and the copper layer 35 is omitted.

In the present invention, a copper material 35 is bonded to the inner surface or end surface of the braking drum 13 made of iron or an iron alloy using the nickel layer 34 as a buffer layer. That is, in joining the iron or iron alloy material 33 and the copper material 35, an intermediate layer is provided between the iron or iron alloy material 33 and the copper material 35 so that practical bonding strength can be maintained even at a high temperature. Nickel layer 34
Intervene. Nickel layer 34 is made of iron or iron alloy material 33
In order to join the nickel layer 34 to the copper material 35, the nickel layer 34 is formed by iron or iron alloy material 33 by ordinary welding such as TIG or MIG.
And the copper material 35.

[Example] A test tube 33 made of iron (S15C) as a base material and having an inner diameter of 50 mm and a length of 5 mm was placed in a TIG.
After the nickel layer 34 was overlaid by welding, the overlaid nickel layer 34 was polished to a thickness of 1 mm and smoothed. Next, a copper layer 35 was built up on the surface of the nickel layer 34. As a result of analyzing the elements at the joint surface (facing surface) between the iron layer 33 and the nickel layer 34 thus obtained, the nickel layer 3
4, the presence of about 50% of iron was confirmed, and as shown by the line 42 in FIG. 10, a gradient composition change was observed. That is, the boundary between the iron layer 33 as the base material on the end face of the braking drum 13 and the nickel layer 34 as the intermediate layer contains 40 to 60% of the iron as the base material (iron diffuses into the nickel layer. And the presence of an alloy layer whose iron content gradually decreased toward the center of the nickel layer 34 was confirmed. Similarly, as a result of analyzing elements on the bonding surface (facing surface) of the copper layer 35 and the nickel layer 34, as shown by a line 41 in FIG. The presence of an alloy layer containing 60% copper (copper diffuses into the nickel layer) and having a gradually decreasing copper content toward the center of the nickel layer 34 was confirmed.

In the above-described embodiment, the magnet support cylinder is reciprocated in the axial direction with respect to the braking drum, so that the magnet is positioned between the braking position where the magnet faces the ferromagnetic plate and the non-braking position where the magnet does not face the ferromagnetic plate. Although the description has been given of the case of the switching type magnetic eddy current reduction device, the present invention is not limited to this. One magnet support cylinder is provided for the braking drum as disclosed in JP-A-4-88,867. Is rotated to switch between a braking position in which two magnets having the same polarity face the common ferromagnetic plate and a non-braking position in which two magnets having different polarities face the common ferromagnetic plate. Eddy current reducers,
A stationary magnet support cylinder and a movable magnet support cylinder are arranged inside a braking drum as disclosed in JP-A-4-12,659,
By rotating one of the magnet support cylinders, a braking position in which the magnets having the same polarity of both magnet support cylinders entirely face the common ferromagnetic plate, and a pair of magnets having different polarities of both magnet support cylinders Can be applied to a magnet type eddy current reduction device of a type that switches to a non-braking position that is completely opposed to a common ferromagnetic plate.

The present invention can be applied not only to the braking drum of a permanent magnet type eddy current reduction device, but also to the braking drum of an electromagnet type eddy current reduction device as disclosed in Japanese Patent Application Laid-Open No. 63-274,359.

[0026]

According to the present invention, as described above, in joining an iron or iron alloy material and a copper material, by interposing nickel as an intermediate layer, an alloy layer with each base material (copper and nickel, Iron and nickel) are formed, the bonding strength of the iron or iron alloy material and the copper material at high temperatures is improved, the coefficient of thermal expansion and electrical resistance are reduced by each alloy layer, and the iron or iron alloy material and the copper material Abrupt changes (gap) in physical properties (coefficient of thermal expansion and electrical resistance) between them are reduced, and braking torque characteristics as a composite metal braking drum are improved.

The separation resistance and crack resistance of the joint between the iron or iron alloy material and the copper material at high temperatures are improved, and the reliability of the braking drum of the eddy current type speed reducer is improved.

Nickel as an intermediate layer can reduce the difference in electric resistance between iron or an iron alloy material and a copper material, thereby improving electric corrosion resistance, reducing loss by smoothing an eddy current circuit, and suppressing heat generation. .

[Brief description of the drawings]

FIG. 1 is a front sectional view of an eddy current type reduction gear provided with a braking drum according to the present invention.

FIG. 2 is a side sectional view of the eddy current type speed reducer.

FIG. 3 is a front sectional view of a brake drum according to another embodiment of the present invention.

FIG. 4 is a front sectional view of a brake drum according to another embodiment of the present invention.

FIG. 5 is a front sectional view of a brake drum according to another embodiment of the present invention.

FIG. 6 is a front sectional view of a braking drum according to another embodiment of the present invention.

FIG. 7 is a front sectional view of a braking drum according to another embodiment of the present invention.

FIG. 8 is a front sectional view of a brake drum according to another embodiment of the present invention.

FIG. 9 is a front sectional view of a brake drum according to another embodiment of the present invention.

FIG. 10 is a diagram showing a composition of a bonding portion between a mother phase and a copper layer of the braking drum according to the present invention.

[Description of Signs] 4: Rotating shaft 5: Mounting flange 7: Brake drum 9:
Boss 9a: Flange 12: Spoke 13: Brake drum 13a: Cooling fin 18: Guide cylinder 18a: Outer peripheral wall 18b: Inner peripheral wall 19: Magnet support cylinder 20: Permanent magnet 21: Ferromagnetic plate 31: Frame plate 3
1a: Reinforcing rib 33: Iron layer 34: Nickel layer 35: Copper layer 35a: Cylindrical body 35b: Cooling fin 3
8: Annular groove

Continuing from the front page (72) Inventor, Tadaharu Yamada 8 Dosana, Fujisawa-shi, Kanagawa Prefecture, in Isuzu Central Research Institute Co., Ltd. ) Inventor, Masaki Asano, 8 Tsudosana, Fujisawa, Kanagawa Prefecture, Isuzu Central Research Laboratories Co., Ltd.

Claims (2)

[Claims] 1. A brake drum mainly composed of iron coupled to a rotating shaft, a magnet support cylinder made of a magnetic material disposed inside the brake drum, and an inner peripheral surface of the brake drum on the magnet support cylinder. In an eddy current reduction device having a large number of magnets coupled to face each other, a nickel layer having a thickness of 0.5 to 2 mm is build-up welded to an end surface of the braking drum containing iron as a main component to form the nickel layer. A braking drum for an eddy current type reduction gear, characterized in that a copper layer is overlay-welded on the surface. 2. A base material containing 40 to 60% of a base material at a boundary between an iron layer and a nickel layer as a base material and a boundary between a copper layer and a nickel layer as a base material at the end face of the braking drum. The braking drum of an eddy current reduction device according to claim 1, wherein there is an alloy layer whose material content gradually decreases toward the center of the nickel layer.