JPH05236732A - Rotor of eddy current type brake - Google Patents

Abstract

PURPOSE:To obtain a eddy current type brake wherein braking force being stable for a long term is secured. CONSTITUTION:A 40-85wt.% nickel-15-60wt.% chromium alloy layer 6 is made as the uppermost layer on the copper layer 3 made at the inside periphery of the cylinder of a rotor 1 opposed to a magnet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the eddy current type brake rotating body used in large vehicles such as buses and trucks.

[0002]

2. Description of the Related Art For large vehicles such as buses and trucks,
In addition to foot brakes and exhaust brakes, eddy current type brakes are provided. Its purpose is to prevent the decrease of the braking force due to the repeated braking operation of the foot brake together with the exhaust brake, and improve the safety.

Various types of eddy current type brakes have been developed and published. The basic structure is that a rotating body formed of a ferromagnetic body and connected to a rotating shaft and a magnet that generates a magnetic flux and does not rotate are arranged so that the rotating body cuts the magnetic flux. Is what When the rotating body rotates, the magnetic flux is cut off, and when the magnetic flux interlinking with the rotating body is increased or decreased, when the magnet is sandwiched in the rotating body and two microcircuits are arranged before and after the magnet, Due to Lenz's law, eddy currents with different directions are generated in the minute circuit. It is considered that the two minute circuits have become small magnets having NS due to this eddy current, and when the magnet poles are repelled and attracted and the magnets are not fixed, the magnets accompany the rotating body. Rotate.
However, in the eddy current type brake, since the magnet is fixed, a force that pulls back the rotor in reverse, that is, a braking force acts on the rotor. This braking force is used.

There are two types of magnets, permanent magnets and electromagnets. The former is movably mounted so that when the eddy current brake is actuated, it is moved so that the rotating body cuts off the magnetic flux. And the latter is fixed,
Only when the eddy current type brake is operated, an electric current is passed through the coil to generate a magnetic flux.

The braking force generated in the rotating body by the eddy current is large if the electric resistance of the rotating body is small. Therefore, in order to reduce the electric resistance and increase the eddy current, a metal layer is formed on the inner peripheral surface of the cylindrical portion of the rotating body facing the magnet.
The metal layer may consist of three layers of nickel-copper-nickel, as shown in FIG. 3, or nickel-copper-, as shown in FIG.
It is composed of three layers of chromium. The nickel layer 2 formed on the inner peripheral surface of the cylindrical portion of the rotating body 1 facing the magnet has a thermal expansion located between iron and copper, which are materials of the rotating body 1, so that the temperature rise caused by the eddy current is increased. The relative displacement between the rotating body 1 and the copper layer 3 due to the above is alleviated, and the copper layer 3 is prevented from peeling off. The electrical conductivity of the copper layer 3 formed on the surface of the nickel layer 2 is about 6 times that of iron, and therefore increases the eddy current generated in the rotating body 1. Formed on the surface of the copper layer 3,
Since the hardness of the outermost nickel layer 4 or the chromium layer 5 is higher than that of copper, the surface hardness of the metal layer is maintained.

The nickel layer 2 has a thickness of 0.01 to 0.0.
5 mm, the thickness of the copper layer 3 is 0.1 to 0.2 mm, and the thickness of the nickel layer 4 or the chromium layer 5 is 0.02 to 0.06 m.
m, the formation is performed by plating or welding.

[0007]

In these prior arts, when the outermost layer is the nickel layer 4, the oxidation resistance of the nickel layer 4 becomes high when the rotor 1 reaches a high temperature of about 600 ° C. which is reached during braking. Since it is insufficient, oxidative wear progresses. Further, since the nickel layer 4 has insufficient strength, thermal fatigue occurs due to a thermal cycle due to braking and cutting, and cracks are likely to occur. When the wear and cracks of the nickel layer 4 progress, the copper layer 3 is exposed, the oxidation and wear of the copper layer 3 rapidly progress, and the braking force decreases.

When the outermost layer is the chromium layer 5, the chromium layer 5 has sufficient oxidation resistance, but particularly when the chromium layer 5 is formed by plating, it is brittle and has a difference in thermal expansion coefficient from that of copper. Since it is large, thermal fatigue is likely to occur due to the thermal cycle, and cracks are likely to occur, as in the case of the nickel layer 4.
In any case, it is not possible to obtain an eddy current type brake in which a stable braking force is secured for a long period of time.

The present invention has been made for the purpose of solving the problems of the prior art.

[0010]

Means for solving the above problems will be described below with reference to FIG. 1 corresponding to the embodiment. This invention is formed of a ferromagnetic material, and a rotating body connected to a rotating shaft, and a magnet that generates a magnetic flux and does not rotate, are arranged so that the rotating body cuts the magnetic flux, In an eddy current type brake that applies a braking force to the rotating body by the eddy current generated in the rotating body, 40 to 85 weight on the copper layer 3 formed on the inner peripheral surface of the cylindrical portion of the rotating body 1 facing the magnet. % Nickel-15 to 60 wt% chromium alloy layer 6 is formed as the outermost layer.

[0011]

In the structure thus constituted, the nickel-chromium alloy layer 6 itself has excellent oxidation resistance even at high temperature and has sufficient strength, so that the occurrence of wear and cracks is suppressed, The layer 3 is stably protected for a long period of time.

[0012]

FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, 1 is a rotor, 2 is a nickel layer, 3 is a copper layer, and 6 is a nickel-chromium alloy layer. Nickel-
As the chromium alloy layer 6, one having a nickel content of 40 to 85% by weight and a chromium content of 15 to 60% by weight is used. This range is selected because if the chromium content is less than 15% by weight, the oxidation resistance is insufficient, and if it exceeds 60% by weight, the ductility is insufficient.

At a high temperature of about 600 ° C. due to an eddy current that efficiently flows through the copper layer 3 of the rotating body 1 during braking, the copper layer 3 is easily oxidatively abraded when the nickel-chromium alloy layer 6 is not present, and braking is performed. Performance decreases in the short term. However, when the nickel-chromium alloy layer 6 is formed on the copper layer 3, the oxidation of the copper layer 3 is completely suppressed. Further, the nickel-chromium alloy layer 6 itself has excellent oxidation resistance even at a high temperature, and therefore is resistant to oxidative wear. Further, the nickel-chromium alloy layer 6 has a higher strength than conventional nickel and chromium and has a coefficient of thermal expansion equivalent to that of copper, so that the occurrence of cracks due to thermal fatigue due to braking and cutting is suppressed. In this way, the state of the nickel-chromium alloy layer 6 is unlikely to change, so the copper layer 3 is stably protected for a long period of time, and the reliability of the eddy current brake is improved.

Formation of the nickel-chromium alloy layer 6 on the inner peripheral surface of the cylindrical portion of the rotating body 1 is difficult by plating, and therefore is performed by thermal spraying. However, decompression thermal spraying can obtain a dense coating for maintaining oxidation resistance. It is desirable that

The nickel-chromium alloy layer 6 has a larger electric resistance than the conventional nickel layer 4, but since the formed film thickness is as thin as 0.03 to 0.05 mm, it hardly affects the braking torque. As shown in FIG. 5, a braking torque equivalent to that of the conventional nickel layer 4 can be obtained. FIG. 5 is a diagram showing a braking torque characteristic of a simulator tester that is supposed to be mounted on an actual vehicle. In addition, as a result of examining the number of times until cracks were generated by applying a thermal cycle of 600 ° C. ← → 50 ° C. by braking and cutting with a simulator tester, the conventional nickel plating layer was 850 times, the nickel-chromium alloy of the present invention. The thermal sprayed layer was 1,700 times, and the durability was doubled.

In the above-mentioned embodiment, three layers of nickel layer 2-copper layer 3-nickel-chromium alloy layer 6 are formed as the metal layer on the inner peripheral surface of the cylindrical portion of the rotating body 1, but the reduced pressure thermal spraying is performed. When the metal layer is formed by the above method, even if the copper layer is directly formed on the rotating body, peeling does not occur because the joining of the rotating body and the copper layer is sufficient, and as shown in FIG. Two layers of the nickel-chromium alloy layer 6 may be used.

[0017]

As described above, the present invention is
40 to 8 on the copper layer formed on the inner peripheral surface of the cylindrical portion of the rotating body
5% by weight nickel-15 to 60% by weight chromium alloy layer is formed as the outermost layer. Therefore, the state of the nickel-chromium alloy layer is unlikely to change even at high temperatures during braking, and the copper layer is stably protected for a long period of time. Therefore, according to the present invention, it is possible to obtain the effect of obtaining the eddy current brake in which a stable braking force is secured for a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional technique.

FIG. 4 is a cross-sectional view showing a conventional technique.

FIG. 5 is a diagram showing a braking torque characteristic of a simulator tester that is supposed to be mounted on an actual vehicle.

[Explanation of symbols]

 1 Rotating Body 2 Nickel Layer 3 Copper Layer 6 Nickel-Chromium Alloy Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Kikuchi 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Corporation

Claims (1)

[Claims] 1. A rotating body formed of a ferromagnetic body and connected to a rotating shaft, and a magnet that generates a magnetic flux and does not rotate are arranged so that the rotating body cuts the magnetic flux. In an eddy current type brake that gives a braking force to the rotating body by an eddy current generated in the rotating body, 40 to 85% by weight on a copper layer formed on an inner peripheral surface of a cylindrical portion of the rotating body facing the magnet. A rotating body for an eddy current brake, characterized in that a nickel-15-60 wt% chromium alloy layer is formed as an outermost layer.