JPH07118902B2 - Eddy current type speed reducer - Google Patents

Description

The present invention mainly relates to an eddy current type speed reducer mainly assisting a friction brake of a large vehicle, and particularly effectively avoids dragging of a braking disc due to magnetic leakage during non-braking. The present invention relates to an eddy current type speed reducer.

[Prior Art] In the eddy current type speed reducer disclosed in JP-A-1-298947, a pair of magnetic braking plates are rotatably disposed between a pair of braking disks coupled to a rotating shaft. A magnet support plate is fixed between a pair of magnetic control plates, and a large number of permanent magnets are connected to each other so that the polarities with respect to the braking discs are circumferentially equidistant and are alternately different. As a pair of magnetic control plates, a non-magnetic plate made of aluminum or the like and ferromagnetic plates having substantially the same area as the permanent magnets are arranged at equal intervals in the circumferential direction.

When the magnetic braking plate is held at the position where the ferromagnetic plate faces the permanent magnet during braking, the magnetic field from the permanent magnet penetrates the ferromagnetic plate and acts perpendicularly on the braking disc, and the braking disc crosses the magnetic field. At this time, an eddy current is generated in the braking disc, and the braking disc receives the braking torque.

During non-braking, when the ferromagnetic plate is displaced by the arrangement pitch of the permanent magnets or the magnetic control plate is held at the rotating position, two permanent magnets adjacent to each other in the circumferential direction are provided between the pair of ferromagnetic plates when viewed from the outer peripheral side. A short-circuited magnetic closed circuit is formed between two adjacent permanent magnets and a pair of left and right ferromagnetic plates that are partially sandwiched, and the magnetic field exerted on the braking disc becomes extremely weak, and the braking torque received by the braking disc is Very small

[Problems to be Solved by the Invention] However, since the magnetic flux leaking from the circumferential center portion of the permanent magnet that is not sandwiched between the pair of ferromagnetic plates acts on the braking disc, the braking disc receives drag torque. There is a problem. If the magnetic control plate is thickened in order to reduce the magnetic flux leaking from the permanent magnet to the braking disc, the entire device becomes heavier, and the gap between the permanent magnet and the braking disc becomes wider, so that the ferromagnetic plate is changed from the permanent magnet during braking. The magnetic flux that passes through and reaches the braking disc is reduced,
The control torque decreases.

In view of the above problems, it is an object of the present invention to provide an eddy current type speed reducer that effectively eliminates leakage flux during non-braking without increasing weight.

[Means for Solving the Problem] In order to achieve the above object, the structure of the present invention has a pair of left and right braking discs connected to a rotating shaft, and has an inner space made of a non-magnetic material and having a rectangular cross section. With a cylindrical fixed frame,
A large number of ferromagnetic plates are connected to both side walls of the fixed frame at equal intervals in the circumferential direction, and a pair of left and right magnet support wheels are supported in the inner space of the fixed frame so that they can rotate relative to each other. The same number of permanent magnets as the plates are arranged so as to face the ferromagnetic plate and the polarities of the ferromagnetic plates are alternately different in the circumferential direction, and one magnet supporting wheel faces the other magnet supporting wheel. There is provided means for rotating the non-braking position where the permanent magnets have the same pole and the braking position where the permanent magnets facing each other have different polarities.

[Operation] During braking, if the polarities of the opposing permanent magnets of the pair of left and right magnet support wheels are reversed, the directions of the magnetic fields of both permanent magnets will match, and they will pass through the ferromagnetic plate and become perpendicular to the braking disc. A strong magnetic field. When the rotating braking disc crosses the magnetic field, an eddy current is generated in the braking disc, and the braking disc receives the braking torque.

When one magnet supporting wheel is rotated by the arrangement pitch of the permanent magnets during non-braking, the polarities of the facing permanent magnets of the pair of left and right magnet supporting wheels become the same, and the magnetic closed circuit formed by each permanent magnet. Cancel each other out and do not exert a magnetic field on the braking disc.

Embodiment of the Invention FIG. 1 is a front sectional view of an eddy current type speed reducer according to the present invention,
FIG. 2 is a side view of the same. The eddy current type speed reducer according to the present invention includes, for example, a braking disc 3 composed of a pair of left and right conductors coupled to an output rotary shaft 2 of a vehicle transmission, and a non-magnetic disc disposed between the braking discs 3. A fixed frame 5 composed of a body, and a pair of left and right magnet support wheels rotatably supported in an inner space of the fixed frame 5.
It is equipped with 8,8a. The braking disc 3 is fixed by spline-fitting the boss 3a to the rotary shaft 2. The boss 3a, the spokes 3b extending radially from the boss 3a, and the braking disc 3 having the ventilation passage 3c are integrally formed by, for example, casting.

The fixed frame 5 has a tubular shape with an inner space having a rectangular cross section, and is specifically configured by connecting an annular lid plate 5c to a tubular body having a U-shaped cross section. The fixed frame 5 is formed integrally with the spokes 5b extending from the boss 5a in the radial direction, and the boss 5a is supported by the rotating shaft 2 by the bearing 4. The fixed frame 5 is fixed to the gear box of the transmission by any suitable means. A large number of ferromagnetic plates (pole pieces) 6 are coupled to both side walls of the fixed frame 5 at equal intervals in the circumferential direction. Preferably, the ferromagnetic plate 6 is cast during molding of the fixed frame 5.

A pair of left and right magnet support wheels that support a large number of permanent magnets 12, 12a
The bearings 8 and 8a are rotatably supported in the inner space of the fixed frame 5 by bearings 7 and 7a. Lubricating oil-impregnated thin slide plates 14 are joined to the outer surfaces of the magnet support wheels 8 and 8a and slidably contact the ferromagnetic plate 6.

As shown in FIG. 2, the magnet support ring 8a on the right side is made of a non-magnetic material such as aluminum, and the same number of fan-shaped permanent magnets 12a as the ferromagnetic plates 6 are opposed to the ferromagnetic plate 6 and the ferromagnetic plate. The polarities for 6 are arranged so as to be alternately different in the circumferential direction. Preferably, the permanent magnet 12a is cast around the magnet support wheel 8a. Similarly, in the left magnet support wheel 8, the same number of permanent magnets 12 as the ferromagnetic plates 6 are arranged so as to face the ferromagnetic plates 6. The fixed frame 5 is attached to the partial gear 18 formed on the outer peripheral wall of the magnet supporting wheel 8a.
The pinion 15 of the electric motor 16 fixed to is engaged with the magnet support wheel 8a so that the magnet support wheel 8a can be rotated forward and backward by the arrangement pitch p of the permanent magnets 12a. Although not shown, each ferromagnetic plate 6 has substantially the same shape as the permanent magnets 12 and 12a.

Next, the operation of the eddy current type speed reducer according to the present invention will be described. While the pair of braking discs 3 are rotated together with the rotating shaft 2, as shown in FIGS. 1 and 3, during braking, the pair of magnet support wheels 8 and 8a are opposed to each other on the left and right permanent wheels. The magnets 12 and 12a are held in positions where the polarities are reversed. Therefore, the left and right permanent magnets 12, 12a integrally exert a magnetic field perpendicular to the braking disc 3 via the ferromagnetic plate 6. When the rotating braking disc 3 crosses the magnetic field, an eddy current is generated in the braking disc 3 and the braking disc 3 receives the braking torque. At this time, as shown in FIG.
From the permanent magnets 12 and 12a to the ferromagnetic plate 6, the braking disc 3, the adjacent ferromagnetic plate 6, the adjacent permanent magnets 12a and 12, the opposite ferromagnetic plate 6, the opposite braking disc 3, and the adjacent strong plate. A magnetic closed circuit is generated in the magnetic plate 6.

When the left magnet supporting wheel 8 is fixed and the right magnet supporting wheel 8a is rotated by the electric motor 16 by the arrangement pitch p during non-braking, as shown in FIG. Since the polarities are the same and the magnetic closed circuits are offset, no magnetic field is applied to the braking disc 3.

In the embodiment described above, the left magnet supporting wheel 8 is fixed, and the right magnet supporting wheel 8a is fixed by the electric motor 16 to the permanent magnet 12a.
Although it is configured to rotate in the normal and reverse directions by the arrangement pitch, the fluid rolling actuator may rotate, and the left magnet supporting wheel 8 may rotate instead of the right magnet supporting wheel 8a.

EFFECTS OF THE INVENTION As described above, according to the present invention, a cylindrical fixed frame made of a non-magnetic material and having a rectangular cross section is provided between a pair of left and right braking discs coupled to a rotary shaft. , A large number of ferromagnetic plates are connected to both side walls of the fixed frame at equal intervals in the circumferential direction, and a pair of left and right magnet support wheels are supported in the inner space of the fixed frame so as to be rotatable relative to each other. The same number of permanent magnets as the magnetic plate are placed facing the ferromagnetic plate, and the polarities of the ferromagnetic plates are arranged so as to alternate in the circumferential direction, and one magnet supporting wheel faces the other magnet supporting wheel. Since the permanent magnet is rotated to a non-braking position where the permanent magnets have the same pole and a braking position where the permanent magnets have opposite polarities, the pair of magnet supporting wheels face each other during braking. When the polarities of the permanent magnets are held in reverse, the magnetic field directions of both permanent magnets match and they penetrate the ferromagnetic plate to dampen A magnetic field perpendicular to the disk is exerted, but if the polarities of the opposing permanent magnets of the pair of magnet support wheels are kept the same during non-braking,
The magnetic closed circuit of each permanent magnet is canceled out, and no magnetic field is applied to the braking disc.

The fixed frame has almost the same dimensions as the conventional example, that is, the braking force equivalent to that of the conventional example is generated during braking without increasing the weight.
Eliminates the leakage magnetic flux during non-braking and eliminates the drag torque of the braking disc.

[Brief description of drawings]

FIG. 1 is a front sectional view of an eddy current type speed reducer according to the present invention,
FIG. 2 is a side view of the same magnet support wheel, FIG. 3 is a circumferential sectional plan view showing a state of the eddy current type speed reducer during braking, and FIG.
The figure is a circumferentially developed plan sectional view showing a state of the eddy current type speed reducer during non-braking. 2: Rotation axis, 3: Braking disc, 5: Fixed frame, 6: Ferromagnetic plate, 8, 8a:
Magnet support wheel, 12, 12a: Permanent magnet

Claims (1)

[Claims] 1. A tubular fixed frame made of a non-magnetic material and having an inner space with a rectangular cross section is disposed between a pair of left and right braking discs connected to a rotary shaft, and both sides of the fixed frame are surrounded. A large number of ferromagnetic plates are connected at equal intervals in the direction, and a pair of left and right magnet support wheels are supported in the inner space of the fixed frame so that they can rotate relative to each other. , Facing the ferromagnetic plate and arranging so that the polarities with respect to the ferromagnetic plate are alternately different in the circumferential direction, and the permanent magnets facing each other have the same polarity with respect to the other magnet supporting ring. An eddy current type speed reducer comprising means for rotating to a non-braking position and a braking position where the opposing permanent magnets have different polarities.