JPS60241746A - Braking device of motor - Google Patents

Abstract

PURPOSE:To simplify the structure and to improve the durability of a motor by interposing magnetic powder between a permanent magnet and a frictional plate, and providing one at a rotor side and the other at a stator side. CONSTITUTION:Magnetic powder interposed between a permanent magnet 18 and a frictional plate 15 made of a magnetic material is presented intermittently therebetween and imparts the prescribed pressure. The magnet 18 is rotated upon rotating of a rotational shaft 14 during the operation of a motor, and the powder 19 rotates one revolution by the magnetic force of the magnet 18. Then, when a power source of the motor is turned OFF to stop the operation, the powder 19 adhered to the magnet 18 applies a brake force to the shaft 14 by the frictional force from the plate 16.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a braking device for an electric motor that has a simple structure and can improve durability.

There are two methods of braking an electric motor: an electrical braking method and a mechanical braking method. Friction brakes that utilize frictional force are known as mechanical braking methods, and electromagnetic brakes are commonly used. Some particularly small electric motors have a purely mechanical and simple braking device built into the casing. The present invention relates to a braking device for this type of electric motor.

b. Prior Art This type of braking device for a small electric motor will be explained with reference to FIG. a brake shoe 7 that is biased via 6;
The brake shoe 7 is brought into pressure contact with the brake plate 3 to apply braking. 8 is a spring holding plate.

However, according to such a braking device, the brake plate 3
When the brake plate 3 and the brake shoe 7 come into contact with each other under pressure, the noise is loud, and as the brake plate 3 and the brake shoe 7 slide, abrasion dust is generated, resulting in a decrease in durability.

C0 Purpose of the Invention The present invention was made in view of the above circumstances, and aims to provide a braking device for an electric motor that has a simple configuration and can improve durability. In this method, a permanent magnet and a friction plate made of a magnetic material are placed facing each other with a gap therebetween, magnetic powder is interposed between them, and one of the permanent magnet and the friction plate is provided on the rotating body side, and the other is provided on the fixed body side.

d1 Structure of the Invention Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

In FIG. 1, 10 is a casing that houses a stator 11 and a rotor 12, and 13 is a bracket that closes the open end of the casing 10. Rotating shaft 1 of the rotor 12
4 is supported by a boss portion 10a provided at the closed end of the casing 10 and a through hole 13a provided at the center of the bracket 13 via bearings 15, respectively. Reference numeral 16 denotes a friction plate attached to the inner wall surface of the bracket 13 via screws 17, which is made of a magnetic material and has a through hole 1 in the center for inserting the rotating shaft 14.
6a, and is screwed through a flange portion 16b provided on the periphery. Reference numeral 18 denotes a disk-shaped permanent magnet that faces the friction plate 16 with a gap therebetween, and is supported by the rotating shaft 14, with magnetic powder 19 interposed in the gap to generate friction under a predetermined pressure. Board 1
It is in sliding contact with 6.

Function of e0 invention Magnetic powder 1 interposed between friction plate 16 and permanent magnet 18
9 are scattered between the two to apply a constant pressure.

While the electric motor is in operation, the permanent magnet 18 rotates as the rotating shaft 14 rotates, and the magnetic force of the permanent magnet 18 causes
The magnetic powder 19 is also rotating together.

Next, when the electric motor is turned off and its operation is stopped, the magnetic powder 19 attached to the permanent magnet 18 applies a braking force to the rotating shaft 14 by the frictional force with the friction plate 16. In this way, the rotating shaft 14 gradually stops its rotation.

f. Other Embodiments FIG. 2 shows another embodiment in which the same parts as in FIG. A permanent magnet 20 is attached to the tip of the rotary shaft 14.

On the other hand, a cap 21 that covers the periphery of the permanent magnet 20 is formed of a magnetic material, and the inner surface of the cap 21 is opposed to the permanent magnet 20 with a predetermined gap therebetween to form a Wi friction plate 2]a. Magnetic powder 22 is interposed between the friction plate 21a and the permanent magnet 20 to apply a constant frictional force between them.

In this case as well, a constant frictional force is applied to the permanent magnet 20, and a braking action is performed during braking.

Further, as shown in FIG. 3, the permanent magnet 20 is attached to the recess 21b formed on the inner surface of the cap 21, the friction plate 23 is attached to the rotating shaft 14, and magnetic powder is inserted between the permanent magnet 20 and the friction plate 23. Even if 22 is interposed, the same effect can be achieved.

It goes without saying that as the permanent magnets 18 and 20, multi-pole magnets as shown in FIG. 4 can be used.

g1 Effects of the Invention As described above, according to the braking device for an electric motor according to the present invention, a permanent magnet and a friction plate made of a magnetic material are opposed to each other with a gap provided, and magnetic powder is interposed between the two,
Since one of the magnetic powder permanent magnet and the friction plate is provided on the rotating body side, and the other is provided on the fixed body side, reliable braking force can be obtained with a simple configuration. Since the magnetic powder is attracted to the permanent magnet, there is no risk of dust generation as in conventional braking devices, and durability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a conceptual sectional view showing one embodiment of a braking device for an electric motor according to the present invention, FIGS. 2 and 3 are conceptual sectional views showing other embodiments of the present invention, and FIG. 4 is a multi-pole permanent FIG. 5 is a plan view showing a magnet, and a conceptual sectional view showing a conventional braking device for an electric motor. 14--rotating shaft, 16.21a, 23-friction plate,
18, 20... Permanent magnet, 19.22... Magnetic powder. Figure 4 Figure 5

Claims (1)

[Claims] +11 A permanent magnet and a friction plate made of a magnetic material are arranged to face each other with a gap therebetween, and magnetic powder is interposed between the two, and one of the permanent magnet and the friction plate is placed on the side of the rotating body. What is claimed is: 1. A braking device for an electric motor, characterized in that the other is provided on a fixed body side. (2) A braking device for an electric motor according to claim 111, characterized in that a multipolar permanent magnet is used. (3) The friction plate is provided on the fixed body side, and the permanent magnet is attached to the rotating shaft.
The braking device for an electric motor according to item 11 or item (2). (4) Claim No. 1, characterized in that the permanent magnet is provided on the fixed body side, and the friction plate is attached to the rotating shaft.
) or (2).