JPS59172967A - Eddy current brake device - Google Patents

Abstract

PURPOSE:To reduce the degree of decrease of a brake force upon decreasing of an automotive speed by radially providing conductors having small electric intrinsic resistances in a brake disk, thereby reducing the apparent resistance in the disk. CONSTITUTION:A brake disk 12 made of ferromagnetic material secured to an axle 1 at a boss 13 is constructed so that a plurality of rod-shaped conductors 14 having small electric intrinsic resistance are radially buried therein. Pole cores 5, on which exciting coils 4 are wound, are disposed at both sides of the disk 12. The apparent resistance of the disk decreased by the conductors 14, and sufficient brake force can be obtained over the wide speed range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a disc-shaped eddy current brake device used in a railway vehicle.

[Technical background of the invention]

Disk-shaped eddy current brake devices used in railway vehicles generate eddy current in a magnetic braking disc (disc) that is fixed to the axle and rotates integrally with the axle, and the action of this eddy current causes braking. This is a device that brakes the rotation of the axle by generating a brake torque in the opposite direction to the rotational direction of the axle on the disc.

FIGS. 1 and 2 show a conventional disc-type eddy current brake device, in which a braking disk 20 made of a ferromagnetic material 3 is fixed to an axle 1, and A magnetic pole core 5 around which an excitation coil 4 is wound is arranged opposite to both sides of the braking disc 2, and the magnetic pole core 5 is supported by a bogie frame 7 via a fixed frame 6. When the excitation coil 4 is excited while the vehicle is running, the magnetic braking disc 2 becomes a magnetic circuit, and the braking disc 2 is activated by the action of the eddy current generated in the rotating braking disc 2. It is designed to generate brake torque in the opposite direction to the rotational direction of the axle. Note that 1a is a wheel.

[Problems with background technology]

However, in the conventional eddy current brake device described above, the braking disc 2 has a single-plate structure made of ferromagnetic material, so the specific resistance of the braking disc itself is high, and as a result, the speed of the vehicle increases. There was a problem in that the braking force decreased significantly as the brake force was lowered, making it impossible to obtain sufficient braking force.

That is, FIG. 3 shows the braking force characteristics of the conventional eddy current braking device, and when the vehicle speed is the same, the braking force increases as the excitation current increases.

Normally, this excitation current gradually increases from the vehicle speed point max shown in FIG. 3, and finally increases to If max at which the excitation current becomes maximum. Then, when the excitation current reaches a maximum and becomes constant at this point, the braking force decreases as the vehicle speed decreases.However, in the conventional eddy current brake system described above, when the excitation current becomes constant, the braking force decreases as the vehicle speed decreases. Since the braking force decreases significantly as the vehicle speed decreases, the lower the vehicle speed, the less the necessary braking force can be obtained.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to minimize the degree of decrease in braking force as the vehicle speed decreases.
To provide an eddy current brake device capable of obtaining sufficient braking force even when the vehicle speed decreases.

[Summary of the invention]

That is, the present invention lowers the apparent resistivity inside the brake disc by radially providing conductors with low electrical resistivity inside the brake disc, thereby reducing the speed of the vehicle. This reduces the degree of decrease in braking force.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

4 and 5 show the first embodiment of the present invention, and 12 in the figure shows the first embodiment of the present invention. A braking disc made of a ferromagnetic material is fixed to the axle 1 at the base portion 13, and this braking disc 1
2 has a structure in which a plurality of rod-shaped conductors 14 having low electrical resistivity are embedded radially. On both sides of this braking disk 12, magnetic pole cores 5 around which excitation coils 4 are wound are arranged facing the side surfaces of the braking disk 12, similar to conventional eddy current brake devices. The iron core 5 is a fixed frame 6 attached to a bogie frame (not shown).
is supported by

Next, the operation of the eddy current brake device will be explained.

When the excitation coil 4 is excited while the vehicle is running, that is, in a state where the brake disc 12 is rotating together with the axle 1, magnetic flux is generated in the magnetic pole core 5, and 5- the brake circle facing the magnetic pole core 5 is generated. Eddy currents are generated in the plate 12. Therefore, when the vehicle speed is low, that is, when the rotational speed of the brake disc 12 is low, the magnetic flux generated from the magnetic pole core 5 penetrates relatively deeply into the brake disc 12. In the above-mentioned eddy current brake device, conductors 14 with low electrical resistivity are provided radially inside the brake disc 12, so the magnetic flux penetrating into the interior of the brake disc 12 is absorbed by the conductors 14 with low resistivity. Since it interlinks with the conductor 14 and a large eddy current flows through the conductor 14, sufficient braking force can be obtained even when the vehicle speed is low. On the other hand, when the vehicle is running at a high speed, that is, when the brake disc 12 is rotating at a high speed, the magnetic flux does not penetrate much into the brake disc 12 due to the skin effect of the magnetic flux, so the eddy current does not This occurs on the surface of the brake disc 120.

In this case, the braking disc 12 has a conductor 14 with a low specific resistance buried therein, but the surface is made of a ferromagnetic material with a high specific resistance. The eddy current generated in the brake disc 12 is almost the same as the eddy current generated in a conventional brake disk made only of ferromagnetic material, and therefore sufficient braking force can be obtained even when the vehicle speed is high. That is,
If the braking disk is made only of materials with high specific resistance, the braking force at high speeds will be large, but the braking force at low speeds will be small; if the braking disk is made only of materials with small specific resistance, The braking force at low speeds is strong, but the braking force at high speeds is small. However, in the above-mentioned eddy current brake device, an electric resistor is installed inside the braking disk 2, which is made of a ferromagnetic material and has a high resistivity. small conductor 1
Since the 4F radial arrangement lowers the apparent specific resistance inside the braking disc, the braking force characteristics of the eddy current brake device described above are as shown in Figure 6, and therefore sufficient braking is achieved over a wide range of speeds. You can gain power.

FIG. 7 and FIG. 8 show a second embodiment of the present invention, in which conductors 140 embedded radially in the brake disc 12 are connected to each other at the center end of the disc. A ring 1 made of a conductor with low specific resistance is connected to the outer edge of the plate.
5.16, they are electrically connected to each other to lower the conductivity of the eddy current circuit, thereby generating a larger eddy current at low speeds and obtaining a larger braking force.

9 and 10 show a third embodiment of the present invention, in which the conductor 14 buried radially within the brake disc 12 is a hollow pipe-shaped conductor, and this A ? Both ends of the tube-shaped conductor 14 are communicated with the outer surface of the brake disc 12, and air 19 is supplied to the conductor 14 (12) from the openings iy, is.
By circulating the brake fluid, the cooling effect of the brake disc 12 is enhanced.

〔Effect of the invention〕

Since the present invention is as described above, it is possible to suppress the degree of decrease in braking force as the vehicle speed decreases, and therefore, it is possible to obtain sufficient braking force even when the vehicle speed decreases.

[Brief explanation of the drawing]

Fig. 1 is a side view of a conventional eddy current brake device, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a brake force characteristic diagram of a conventional eddy current brake device, and Fig. 4 and fifth
FIG. 6 is a longitudinal sectional front view of an eddy current brake device showing a first embodiment of the present invention and a side view of its braking disk; FIG. 6 is a braking force characteristic diagram of the eddy current brake device shown in FIG. 4; 7 and 8 are longitudinal sectional front views and side views of a braking disk of an eddy current brake device showing a second embodiment of the present invention, and FIGS. 9 and 10 are a third embodiment of the present invention. FIG. 3 is a longitudinal sectional front view and a side view of a braking disk of an eddy current brake device showing an example. DESCRIPTION OF SYMBOLS 1... Axle, 4... Excitation coil, 5... Magnetic pole iron core, 12... Braking disk, 14... Conductor. Applicant's agent Patent attorney Takehiko Suzue 9- Figure 1 Figure 2 24 3 Figure 3 Vehicle crossing Vmax Figure 4 Figure 5 Figure 6 Vehicle speed Vmax Near figure Figure 8 Figure 9 Figure 10 Figure 7 - 19 na 2

Claims (2)

[Claims] (1) A magnetic pole core around which an excitation coil is wound is placed opposite the side surface of a brake disc made of a ferromagnetic material fixed to the axle, and eddy current is generated in the rotating brake disc by excitation of the excitation coil. In a disc-shaped eddy current brake device that brakes the axle by generating a brake torque in the direction opposite to the rotational direction of the axle on the brake disc by the action of this eddy current, an electric current is installed inside the brake disc. An eddy current brake device characterized by a radial arrangement of conductors with low specific resistance. (2) The eddy current brake device according to claim (1), wherein the radially arranged conductors are electrically connected to each other.