JPS591417Y2 - Eddy current clutch/brake - Google Patents

Description

[Detailed description of the invention] This invention relates to an eddy current clutch/brake using a permanent magnet.

For example, in an electric point machine, it is necessary to use a clutch in order to prevent an adverse effect on the reduction gear mechanism when starting and stopping the motor, and to prevent burnout of the motor when operation is interrupted.

Conventionally, friction type clutches and thin current type electromagnetic clutches are known as clutches.

Friction type clutches have the disadvantage that the transmitted torque changes due to changes in temperature, wear of the friction plates, etc., so periodic adjustments are required and maintenance is extremely troublesome.

Although the eddy current clutch eliminates the above drawbacks, it uses an electromagnet, so it requires a power supply and the coil wiring is complicated.

This is troublesome, and there is a risk that power transmission will not occur due to a failure such as coil breakage or, in particular, a power outage.

In view of the above points, one of the inventors of this invention previously proposed a device that solved the drawbacks of the conventional eddy current type clutch by using a permanent magnet instead of an electromagnet.

However, as illustrated in FIG. 1, the proposed eddy current clutch includes a disc 3 fixed to the rotating shaft 2 of the motor 1, a cylindrical portion 4 connected to the disc, and a bearing mounted on the clutch case 5. Another disk 7 is rotatably supported via a magnet 6, and cylindrical permanent magnets 8a and 8b are respectively attached to the disk 7.
are arranged so that different poles face each other on opposite sides of a rotating disk 10 fixed to an output shaft 9. Therefore, the structure is complex and the number of parts is large. The disadvantages are that it is time consuming and expensive.

This idea simplifies the structure of eddy current clutches and brakes using permanent magnets by integrating opposing permanent magnets on opposite sides of the rotating disk.
Moreover, the purpose is to apply magnetic force with high efficiency.

Although this invention can be applied to both clutches and brakes, next, an embodiment in which it is applied to a clutch will be described with reference to FIGS. 2 and 3.

In this invention, a plurality of horseshoe-shaped permanent magnets 14 are arranged on a disc 13 fixed to a rotating shaft 12 of a motor 11 in the circumferential direction of the disc.

The permanent magnets 14 have respective opposing magnetic poles 14 a
, 14b so that the envelope line connecting the gap 14C between them in the circumferential direction of the disk 13 forms a circle centered on the rotation axis 12.
It is fixed to the side surface of the disc 13 on the output shaft 15 side.

The conductive rotating plate 1 is fixed to one end of the output shaft 15.
6 has a bottomed cylindrical shape that opens toward the motor side, and its end edge is fitted into the gap 14C between each permanent magnet with a slight gap between it and the opposing magnetic pole.

Further, each permanent magnet is connected to a rotary plate 1 as shown in FIG. 2a.
The magnetic poles existing on the same side with respect to 6 are arranged so that the polarity changes alternately along the circumferential direction of the rotating plate.

17 is a motor case, and 18 is a clutch case.

In this way, when a current is applied to the motor 11 to rotate it, the rotating shaft 12, disk 13, and permanent magnet 14 rotate.
The magnetic flux of each permanent magnet is cut by the rotating plate 16, and eddy current is generated in the rotating plate.

A magnetic field is generated by this eddy current, and a force acts on the rotary plate 16, causing it to rotate in the same direction as the magnet.

That is, the rotation of the motor is transmitted to the rotating plate 16, and the output shaft 15 rotates to supply output to the outside.

If an overload is applied to the rotating output shaft 15 due to interference or the like, slippage occurs between the rotating plate 16 and the permanent magnet 14, and the rotating shaft 12 of the motor to which the permanent magnet is fixed will rotate. Since the motor can continue to operate, burnout of the motor can be prevented.

When electromagnets are used as magnets for generating eddy currents, the polarities are aligned, so the transmission force is weak, and to increase this, a strong electromagnetic force is required.

Furthermore, the rotary plate serving as the inductor also requires processing to be divided in the circumferential direction.

In contrast, in the present invention, since a horseshoe-shaped permanent magnet is used, adjacent polarities can be easily made to differ in the direction of rotation, and there is no need to divide the rotating plate. , Torque is efficiently transmitted even with weak electromagnetic force.

In the embodiment shown in FIG. 2, the permanent magnets are arranged so that the lines of magnetic force between their magnetic poles are perpendicular to the axis of rotation of the motor, so the rotating plate 16 needs to be formed into a cylindrical shape.
Therefore, the number of manufacturing steps increases, and the distance from the disc 13 to the rotary plate 16, that is, the axial length of the clutch must increase.

On the other hand, as shown in FIG. 3, if the permanent magnet 14 is arranged so that the lines of magnetic force between its magnetic poles are parallel to the axis of rotation, a simple flat plate can be used as the rotating plate 16'.
Manufacturing costs are also reduced, and the axial length of the clutch can also be reduced.

It goes without saying that in order to apply this invention to a brake, the disk 13 in the above embodiment may be fixed so as not to rotate, and the output shaft 15 may be used as a load shaft.

As mentioned above, since this invention uses a horseshoe-shaped permanent magnet, the permanent magnet can be attached by simply fixing it to a flat plate, and the rotary plate directly connected to the output shaft or load shaft can be attached to the gap between the magnetic poles. Adjacent permanent magnets are arranged so that they have different polarities, so the rotating plate (
Since the inductor (inductor) can be made continuous without being divided, the structure is simple and manufacturing and assembly are easy.
It is possible to provide latch brakes at low cost.

In addition, the permanent magnets are horseshoe-shaped and are arranged so that the magnetic poles are opposite to each other with the rotating plate in between, and adjacent permanent magnets have different magnetic poles, so if the rotating plate is made continuous. In this case, the magnetic force acts more efficiently and a larger transmission torque or braking torque can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the eddy current clutch before improvement according to this invention, FIG. 2 is a cross-sectional view showing the first embodiment of this invention, and FIG. 2a is a cross-sectional view showing the polar arrangement of the permanent magnets. FIG. 3 is a sectional view of a main part of the second embodiment. 11... Motor, 12... Rotating shaft, 1
3...Disk, 14...Permanent magnet, 15
...Output shaft, 16... Rotating plate, 17.
...Motor case, 18...Clutch case.

Claims (3)

[Scope of utility model registration request] (1) An even number of horseshoe-shaped permanent magnets are placed on the circumference of the motor's rotating shaft, with the magnetic poles of each permanent magnet facing each other on a circle centered on the rotating shaft, and the polarity of adjacent permanent magnets are arranged so as to be alternately different in the circumferential direction of the rotating shaft,
An eddy current clutch/brake in which a conductive rotary plate fixed to an output shaft or a load shaft is fitted between opposing magnetic poles of the permanent magnet with a slight gap between the magnetic poles and the magnetic poles. (2) Eddy current clutch and brake according to claim 1 of the utility model registration claim, characterized in that permanent magnets are arranged so that the lines of magnetic force generated between the magnetic poles are perpendicular to the rotational axis of the motor. . (3) The eddy current clutch/brake according to claim 1, which is a registered utility model, characterized in that the permanent magnets are arranged so that the lines of magnetic force generated between the magnetic poles are parallel to the rotational axis of the motor.