JP2000350432A - Eddy current reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an eddy current reducer which is small as a whole and superior in heat radiating property and has high braking capability. SOLUTION: This reducer is provided with a braking disk 2, coupled with a rotating shaft 3, a guide cylinder 4 composed of nonmagnetic material, which has an inner end wall 4d facing the side surface of the braking disk 2 and is retained by a non-rotating part like the body of a car, a magnet retaining wheel 9 composed of nonmagnetic material which is retained pivotally in the normal and the reverse directions inside the guide cylinder 4, many magnets 8 coupled with the wheel 9 at equal intervals in the peripheral direction, a pair of ferromagnetic members 6 arranged in the guide cylinder 4, in such a manner that base ends face the radial outer end portion and the radial inner end portion of each of the magnets 8 and tips face the side surface of the braking disk 2, a short ring 7 composed of magnetic material which is fixed on the outer end wall 4c of the guide cylinder 4 and has a protruding wall 7a facing each of the magnets 8, and a means for pivoting the magnet retaining wheel 9 at a non-braking position, where the magnets 8 face the protruding wall 7a of the short ring 7 and at a braking position, where the magnets 8 face the ferromagnetic members 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk type eddy current reduction device for assisting friction braking of a large vehicle, and more particularly to a small eddy current reduction device having excellent heat dissipation.

[0002]

2. Description of the Related Art In an eddy current reduction device disclosed in, for example, Japanese Patent Application No. 10-106963, a guide cylinder accommodating a magnet support cylinder is accommodated inside a brake drum. There is a problem in that the generated heat is not sufficiently dissipated and the braking capacity is significantly reduced when the braking drum is overheated.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an eddy current reduction device which is small in size, has excellent heat dissipation, and has a high braking ability in view of the above-mentioned problems.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a construction of the present invention comprises a braking disk coupled to a rotating shaft, and an inner end wall opposed to a side surface of the braking disk. A guide tube made of a non-magnetic material supported by a non-rotating portion, a magnet support wheel made of a non-magnetic material supported in the guide tube so as to be able to rotate forward and backward, A plurality of magnets connected to each other, and a pair of magnets disposed on the guide cylinder such that a base end is opposed to a radially outer end and a radially inner end of each magnet, and a distal end is opposed to a side surface of the braking disk. A short-circuit ring made of a magnetic body having an outer end wall of the guide cylinder fixed and a protruding wall facing each of the magnets; and a non-braking member in which the magnet opposes the protruding wall of the short-circuit ring. Means for rotating the magnet support wheel between a position and a braking position in which the magnet faces the ferromagnetic member. That.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a magnet support wheel made of a non-magnetic material is rotatably supported on an inner end wall of a guide cylinder made of a non-magnetic material having a rectangular cross section close to a braking disk. A short-circuit ring made of a magnetic material having projecting walls at equal circumferential intervals is arranged on the outer end wall of the cylinder. A number of magnets are connected to the magnet support wheel at equal intervals in the circumferential direction so that the magnetic pole faces are in the radial direction, and the tip of the ferromagnetic member whose base end faces the radially outer end of each magnet is placed inside the guide cylinder. It is connected to the end wall and faces the side surface of the braking disk. Similarly, the distal end of the ferromagnetic member whose base end faces the radially inner end of the magnet is connected to the inner end wall of the guide cylinder and is opposed to the side surface of the braking disk. The ferromagnetic member and the protruding wall of the short-circuit ring are provided with a rotation phase different by a half pitch of the magnet.

Accordingly, when each magnet is sandwiched between a pair of ferromagnetic members, a magnetic field is applied to the braking disk to generate a braking torque. On the other hand, when the magnet support wheel is rotated by a half pitch of the magnet, the magnet faces the protruding wall of the short-circuit ring, forms a short-circuit magnetic circuit with the short-circuit ring, and does not exert a magnetic field on the braking disk. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an eddy current reduction device according to the present invention includes a braking disk 2 composed of a conductor connected to a rotating shaft 3;
A guide cylinder 4 made of a non-magnetic material and supported on a non-rotating portion such as a vehicle body is provided opposite to the side surface of the braking disk 2. The guide tube 4 includes an outer tube portion 4a, an inner tube portion 4b, an outer end wall 4c, and an inner end wall 4d facing the braking disk 2. A magnet support wheel 9 made of a non-magnetic material is supported by a thrust bearing 10 on the inner end wall 4d of the inner hollow portion 5 having a rectangular cross section of the guide cylinder 4 so as to be able to rotate forward and reverse, while being circumferentially mounted on the outer end wall 4c. Short-circuit rings 7 having a large number of projecting walls 7a at equal intervals are connected. Magnet support wheel 9
A large number of magnets 8 are coupled at equal intervals in the circumferential direction.

The magnet 8 has magnetic pole surfaces at both ends in the radial direction, and the base end surface of the ferromagnetic member 6 is opposed to the radially outer end. On the other hand, the front end 6a of the ferromagnetic member 6 is coupled to the inner end wall 4d of the guide cylinder 4, and forms a flat surface facing the side surface of the braking disk 2. Similarly, a base end surface of the ferromagnetic member 6 is opposed to a radially inner end of the magnet 8. The front end 6a of the ferromagnetic member 6 is coupled to the inner end wall 4d of the guide cylinder 4, and forms a flat surface facing the side surface of the braking disk 2.

As shown in FIG. 2, the protruding wall 7a of the short-circuit ring 7 is out of phase with the ferromagnetic member 6 by a half pitch. Although not shown, the radially outer end and the radially inner end of the protruding wall 7 a are partially opposed to the magnetic pole surface of the magnet 8.
Preferably, it is projected to the right in FIG.

In the braking position shown in FIGS. 1 and 2, the magnet 8 is sandwiched between a pair of inner and outer ferromagnetic members 6, and FIG.
As shown in the figure, the magnet 8 applies a magnetic field to the braking disk 2 via the ferromagnetic member 6, and when the rotating braking disk 2 crosses the magnetic field, an eddy current is generated inside the braking disk 2 and the braking torque is generated. Occurs. At this time, a magnetic circuit z is formed between the magnet 8 and the braking disk 2. When the magnet support wheel 9 is rotated by a half pitch of the magnet 8 when the brake is not applied, as shown in FIG. Oppose. At this time, a short-circuit magnetic circuit w is formed between the magnet 8 and the short-circuit ring 7 and does not exert a magnetic field on the braking drum.

According to the present invention, since the magnetic poles of the magnet 8 are arranged in the radial direction, the axial dimension of the guide cylinder 4 can be reduced, and the magnet 8 can be formed only by increasing the radial dimension of the magnet 8. Capacity can be increased. The guide cylinder 4 has an inner cylinder 4b and an outer cylinder 4
a) Since the outer end wall 4c is exposed to the outside air from three sides, the outside air easily enters the gap between the braking disk 2 and the inner end wall 4d, and the braking disk 2 is excellent in heat dissipation.

[0012]

As described above, the present invention provides a brake disk connected to a rotating shaft and a non-magnetic member having an inner end wall facing the side surface of the brake disk and supported by a non-rotating portion such as a vehicle body. A guide tube made of a body, a magnet support wheel made of a non-magnetic material supported in the guide tube so as to be capable of rotating forward and backward, a large number of magnets coupled to the magnet support wheel at equal intervals in the circumferential direction, A pair of ferromagnetic members disposed on the guide cylinder such that a base end is opposed to a radially outer end and a radially inner end of the magnet, and a tip is opposed to a side surface of the braking disk; A short-circuiting ring made of a magnetic material having a protruding wall fixed to the outer end wall and facing each of the magnets; a non-braking position in which the magnet opposes the protruding wall of the short-circuiting ring; And a means for rotating the magnet support wheel at the braking position facing the outer cylinder portion and the inner cylinder portion of the guide cylinder are exposed to the outside air, Since the outside air is likely to enter into the gap between the moving disk and the guide tube, the heat generated in the brake disc during braking is efficiently released. Therefore, a decrease in the braking ability due to heat during braking is suppressed.

In particular, since it is easy to take in the outside air between the guide cylinder and the braking disk, it is possible to minimize the thermal distortion of the braking disk. Therefore, no structural countermeasure against heat is required, and the structure can be simplified and the manufacturing cost can be reduced.

The structural space of the switching mechanism for performing the switching operation between the non-braking and the braking position is reduced, and the entire apparatus can be downsized.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an eddy current reduction device according to the present invention.

FIG. 2 is a plan sectional view showing a braking state of the eddy current reduction device developed in a circumferential direction.

FIG. 3 is a plan sectional view showing the non-braking state of the eddy current reduction device developed in a circumferential direction.

[Explanation of symbols]

2: braking disk 3: rotating shaft 4: guide cylinder 4a: outer cylinder 4b: inner cylinder 4c: outer end wall 5: inner space 6: ferromagnetic member 6a: tip 7: short-circuit ring 7a: protruding wall 8 : Magnet 9: Magnet support wheel 10: Thrust bearing

Claims (1)

[Claims] A guide cylinder made of a non-magnetic material having an inner end wall opposed to a side surface of the brake disk and supported by a non-rotational part such as a vehicle body; A magnet support wheel made of a non-magnetic material supported in a forward and reverse rotation inside a guide cylinder, a number of magnets coupled to the magnet support wheel at equal intervals in the circumferential direction, and a radially outer end of each magnet. A pair of ferromagnetic members disposed on the guide cylinder such that a base end faces a radially inner end and a tip faces a side surface of the braking disk, and an outer end wall of the guide cylinder is fixed; A short-circuit ring made of a magnetic material having a protruding wall facing each magnet; a non-braking position in which the magnet faces the protruding wall of the short-circuit ring; and a braking position in which the magnet faces the ferromagnetic member. Means for rotating the magnet support wheel.