JPH04289761A - Eddy current type deceleration gear - Google Patents

Abstract

PURPOSE:To enhance brake capacity by suppressing flux leakage between poles on the side edge part of a magnet opposing to a rotary brake body. CONSTITUTION:A nonmagnetic magnet guide frame 18 is disposed on the open end side of a rotary brake body 23 comprising a conductor and having a U-shaped cross-section. A magnet supporting ring 19 is supported on the magnet guide frame 18 so that it can protrude or retract into/from the interior of the rotary brake body 23. A large number of permanent magnets 20a, 20b are supported on the magnet supporting ring 19 at same intervals in the peripheral direction and with alternating polarities thus opposing the poles at the opposite ends of the permanent magnets 20a, 20b to a pair of parallel brake faces of the rotary brake body 23.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current speed reduction device mounted on a large vehicle to assist a friction brake, and more particularly to an eddy current speed reduction device that suppresses magnetic flux leakage from magnets to improve braking ability.

0002

2. Description of the Related Art An eddy current speed reduction device for a vehicle using permanent magnets is disclosed in Japanese Patent Laid-Open No. 1-298948. FIG. 6 is a side cross-sectional view of a vehicle eddy current type speed reduction device which differs in braking/non-braking switching operation from that of the above-mentioned publication. A mounting flange 5 is spline-fitted to an output rotating shaft 4 supported by a bearing 3 on an end wall of a gear box 2 of the transmission and protruding from the end wall, and fastened with a nut 6 so as not to come off. An end wall of a brake drum 7 of a parking brake and a flange portion 9a integral with a boss portion 9 of a brake drum 13 of a speed reducer are superimposed on the mounting flange 5, and fastened with a plurality of bolts 10 and nuts 10a.

The brake drum 13 is supported by a number of spokes 12 extending radially from the boss portion 9 . Therefore, the tips of the spokes 12 are joined to the base end of the brake drum 13 by welding. A large number of fins 13a are provided on the outer peripheral wall of the brake drum 13 at equal intervals in the circumferential direction.

Brake drum 13 made of an electrical conductor such as iron
A cylindrical magnet guide frame 18 having an inner cavity with a box-shaped cross section is disposed inside the magnet guide frame 18 . The magnet guide frame 18 is connected to the projecting wall 2 of the gear box 2.
It is fixed by bolts 32 and 33 to a frame plate 31 which is externally fitted and fixed to a. The magnet guide frame 18 may be constructed by connecting annular end wall plates to both ends of the outer cylinder and the inner cylinder, but the illustrated magnet guide frame 18 is made of ordinary iron or the like and has a U-shaped cross section on the left half. a cylindrical frame portion 18a made of a non-magnetic material such as aluminum; and a cylindrical frame portion 18 whose right half has an inverted L-shape cross section and is made of a non-magnetic material such as aluminum.
b are connected by a large number of bolts 14.

A large number of openings are provided at equal intervals in the circumferential direction on the peripheral wall of the outer cylindrical portion or frame portion 18b of the magnet guide frame 18 facing the inner surface or braking surface of the brake drum 13, and each opening is provided with a ferromagnetic plate (pole). piece) 21 is fitted and fixed. In practice, the ferromagnetic plate 21 is cast into the frame part 18b when it is cast from aluminum.

A plurality of actuators (not shown) are supported at equal intervals in the circumferential direction on the frame plate 31 having reinforcing ribs 31a. In the actuator, a magnet support ring 19 is coupled to the end of a rod 17 that projects from a piston fitted into a cylinder into the inner cavity of a magnet guide frame 18. The magnet support ring 19 is supported in the inner space of the magnet guide frame 18 so as to be movable in the axial direction. Permanent magnets 20 facing each ferromagnetic plate 21 are coupled to the outer circumferential wall of the magnet support ring 19 with alternating polarities in the circumferential direction.

During a braking operation, the magnet support ring 19 is projected into the interior of the brake drum 13 via the rod 17 by an actuator, as shown. The rotating brake drum 13 passes through the ferromagnetic plate 21 from the permanent magnet 20 to the brake drum 1.
When crossing the magnetic field extending to the braking surface of 3, eddy currents are generated in the braking drum 13 and the braking drum 13 is subjected to a braking torque. The brake drum 13 generates heat due to eddy currents and is cooled by air directly or by means of fins 13a.

During braking, the permanent magnet 20 and the braking drum 1
3, a magnetic circuit as shown in FIG. 8 is formed. However, as shown in FIG. 7, short-circuit magnetic leakage occurs at both side edges of the permanent magnet 20, which does not apply a magnetic field to the brake drum 13.

[0009]

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to suppress magnetic leakage between magnetic poles at both side edges of a permanent magnet facing a rotating braking body, thereby increasing braking ability.
An object of the present invention is to provide an eddy current speed reduction device.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention has a structure in which a magnet guide frame made of a non-magnetic material is disposed on the open end side of a rotating brake body made of a conductor and having a U-shaped cross section, Protrude the magnet support ring into the inside of the rotating brake body on the magnet guide frame.
A large number of magnets are supported in a retractable manner on a magnet support ring at equal intervals in the circumferential direction and their polarities are alternately reversed. They are facing each other.

[0011]

[Operation] In the present invention, the rotary brake body has a U-shaped cross section, and a large number of magnets supported by an annular magnet guide frame and lined up at equal intervals in the circumferential direction protrude into the inner space of the rotary brake body during braking. The magnet forms a magnetic circuit perpendicular to the pair of braking surfaces of the rotary brake body, and at the same time one edge of the magnet also forms a magnetic circuit through the closed end wall of the rotary brake body. Therefore, magnetic leakage is halved compared to conventional eddy current type reduction gears, and braking capacity is increased.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side cross-sectional view of an eddy current speed reduction device in which the present invention is applied to a drum-shaped rotary braking body, and FIG.
FIG. 2 is a front sectional view taken along line 2A-2A of FIG. The eddy current speed reduction device includes a rotary brake body 23 having a U-shaped cross section as a rotary brake body. That is, a pair of inner and outer brake drums 23a and 23b protruding in the axial direction from the closed end wall 23c are integrally formed with the annular closed end wall 23c connected to the spoke or flange 12a extending from the boss portion of the rotating shaft. An annular magnet guide frame 18 is disposed on the open end side of the brake drums 23a, 23b, and a magnet support ring 19 made of a non-magnetic material.
However, due to the actuator rod 17 (not shown),
It is supported by the magnet guide frame 18 so as to be slidable in the axial direction. A cylindrical body 24 made of a ferromagnetic material is coupled to the plate-shaped magnet support ring 19, and a large number of permanent magnets 20a, 20b are coupled to both the inner and outer surfaces of the cylindrical body 24 at equal intervals in the circumferential direction.

Preferably, each permanent magnet 20a has a ferromagnetic plate 21a coupled to the inner surface of the brake drum 23a or the end surface facing the brake surface, and each permanent magnet 20b
A ferromagnetic plate 21b is coupled to the end face facing the braking surface of b. Further, both side edges of each permanent magnet 20a, 20b are connected to each other by annular frame plates 25, 26 made of a non-magnetic material. In this way, the large number of permanent magnets 20a, 20b are arranged so that their polarities alternate in the circumferential direction.

During a braking operation, as shown in FIG. 1, when the magnet support ring 19 is moved into the inner space of the rotary brake body 23 having a U-shaped cross section, the ferromagnetic plate 2 is moved by the rod 17 of the actuator.
1a, the permanent magnet 20a, the cylindrical body 24, the permanent magnet 20b, and the ferromagnetic plate 21b are one permanent magnet, and the brake drum 23
a, 23b show opposite polarity. As shown in FIG. 2, a pair of adjacent permanent magnets 20a and 20b are attached to the brake drum 23.
a, 23b to form a magnetic circuit between each brake drum 2.
Eddy currents are generated in 3a and 23b. At the same time, as shown in FIG. 1, one side edge of each permanent magnet 20a, 20b forms a magnetic circuit with the closed end wall 23c of the rotary brake body 23, generating an eddy current in the closed end wall 23c. Therefore, the braking force of the rotary braking body 23 is increased.

When the actuator rod 17 pulls out the magnet support ring 19 from the inner space of the rotary brake body 23, which has a U-shaped cross section, when the brake is not applied, the permanent magnets 20a and 20b no longer exert a magnetic field on the rotary brake body 23. The rotary brake body 23 does not receive any braking force.

FIG. 3 is a side cross-sectional view of an eddy current reduction gear in which the present invention is applied to a disc-shaped rotary braking body, and FIG. 4 is a cross-sectional view taken along line 4 in FIG.
It is a front sectional view taken along A-4A. The rotary brake body 43 includes a pair of left and right annular brake discs 43 having braking surfaces parallel to each other.
a, 43b and a cylindrical closed end wall 4 connecting the outer peripheral edges of both.
3c, the braking disk 43b is connected to the boss portion 9 of the rotating shaft via the spokes 12. On the outer surface of each brake disc 43a, 43b and closed end wall 43c,
A large number of fins 46 are formed at equal intervals in the circumferential direction. The magnet guide frame 18 is a cylindrical body coaxial with the boss portion 9, and has a rotary brake body 43.
It is integrally provided with a thick circular frame plate 47 that protrudes into the inner cavity. A large number of radial guide grooves 49 are formed inside the frame plate 47 at equal intervals in the circumferential direction, and a permanent magnet 20 having a substantially rectangular parallelepiped shape is slidably supported inside the guide grooves 49.

The magnet guide frame 18 is provided with openings 47a and 47b communicating with the guide groove 49 on the plate surface of the peripheral edge projecting into the inner space of the rotary brake body 43. Ferromagnetic plates 21a and 21b covering the surface are combined. The permanent magnet 20 is made slidable by suitable means between the position shown in FIG. 3 and the position shown in chain lines in FIG.

FIG. 5 is a front view showing a schematic structure of a magnet support ring 55 that causes the permanent magnet 20 to protrude into or retire from the inner space of the rotary brake body 43 along the guide groove 49 of the frame plate 47. It is. A magnet support ring 5 is attached to the boss portion of the magnet guide frame 18.
5 is rotatably supported, and a link 53 is connected between each permanent magnet 20 and a magnet support ring 55 by pins 52 and 54. When the magnet support ring 55 is rotated in the direction of arrow x when braking is not applied, the permanent magnet 20 is pulled by the link 53 and moves into the guide groove 4.
9 to the position shown by the chain line, and no longer exerts a magnetic field on the rotary brake body 43. A groove extending from the guide groove 49 to the magnet support ring 55 is provided in the frame plate 47 so as not to hinder the operation of the link 53.

During a braking operation, as shown in FIG. 3, when the permanent magnet 20 is projected into the inner space of the rotary brake body 43, a magnetic circuit shown by the arrow is formed, and the brake disk 4 of the rotary brake body 43 is
Eddy currents are generated in 3a, 43b and the closed end wall 43c, and the rotary brake body 43 receives braking torque. At this time, permanent magnet 2
Since a magnetic circuit is formed between the outer circumferential edge of 0 and the closed end wall 43c, magnetic leakage is halved compared to the conventional example, and braking ability is increased.

The present invention is not limited to permanent magnets, but also electromagnets, by arranging both ends of the iron core in the inner space of a braking drum or braking disc having a U-shaped cross section, thereby preventing short-circuit magnetism at one edge of the electromagnet. Leakage is eliminated and braking ability can be increased.

[0021]

Effects of the Invention As described above, the present invention includes a magnet guide frame made of a non-magnetic material arranged on the open end side of a rotation braking body having a U-shaped cross section made of a conductor, and rotating a magnet support ring on the magnet guide frame. A large number of magnets are supported in a magnet support ring at equal intervals in the circumferential direction and their polarities are alternately reversed. It is placed opposite the parallel braking surfaces, and one side edge of the magnet also forms a magnetic circuit effective for braking between the closed end wall of the rotary braking body, so magnetic leakage is halved and the braking Capacity can be increased.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view showing essential parts of an eddy current reduction gear according to the present invention.

FIG. 2 is a front cross-sectional view taken along line 2A-2A in FIG. 1;

FIG. 3 is a side cross-sectional view showing a main part of an eddy current reduction gear according to a second embodiment of the present invention.

FIG. 4 is a front cross-sectional view taken along line 4A-4A of FIG. 3;

FIG. 5 is a schematic configuration diagram of a magnet support ring in the eddy current speed reduction device of FIG. 3;

FIG. 6 is a side sectional view of a conventional eddy current speed reduction device.

FIG. 7 is a side sectional view showing an enlarged main part of the eddy current speed reduction device.

FIG. 8 is a front sectional view of the same.

[Explanation of symbols]

Claims (1)

[Claims] Claim 1: A magnet guide frame made of a non-magnetic material is arranged on the open end side of a rotary brake body having a U-shaped cross section made of a conductor, and a magnet support ring can be protruded and retracted from the magnet guide frame into the interior of the rotary brake body. A large number of magnets are supported on a magnet support ring at equal intervals in the circumferential direction and with their polarities alternately reversed, and the magnetic poles at both ends of each magnet are opposed to the mutually parallel braking surfaces of the rotating braking body. An eddy current reduction device characterized by: