JPH05103442A - Hysteresis brake and electric motor with brake - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a hysteresis brake that can obtain a stable braking action, and an electric motor with a brake that is easy to install the hysteresis brake. [Structure] A permanent magnet 19 is attached to a rotary shaft 16 of an electric motor 15.
The yoke 20 to which is fixed is supported via the bearing 18, and the yoke 20 is fixed to the bracket 5. Further, a hub 22 whose end surface abuts on the inner ring side end surface of the bearing 18 is fitted and fixed to the rotary shaft 16. The hysteresis plate 21 and the permanent magnet 19 are opposed to each other with the space S therebetween. Even if the electric motor 15 is stopped, the rotary shaft 16 rotates inertially, but the rotary shaft 16 is braked by the hysteresis brake 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a general-purpose electric motor which is a drive source for industrial and consumer machines, and more particularly to an electric motor with a brake equipped with a brake for braking a rotating shaft to hold it stationary.

As a conventional brake-equipped electric motor, a brake-equipped electric motor having a structure shown in a sectional view in FIG. 7 has been proposed (see Japanese Utility Model Publication No. 49-39044). To briefly describe with reference to the drawings, in this electric motor with brake 1, a stator core 3 around which a primary winding 2 is wound is provided between a front bracket 4 and a rear bracket 5 (not shown).
It is fixed together with bolts. A rotor core 7 in which cage-shaped conductors short-circuited to each other by an end ring 6 are embedded is arranged in a field space inside the center hole of the stator core 3, and the rotor core 7 is a bearing. It is integrally fixed on a rotary shaft 10 rotatably supported by brackets 4 and 5 by 8 and 9.

In the brake-equipped electric motor 1 having such a schematic structure, an annular brake shoe 11 is fitted and fixed in an annular groove formed in the annular protruding portion 5a of the rear side bracket 5, and the brake shoe is formed. A disk-shaped disk 12 that is in frictional sliding contact with a flat surface protruding from the protruding portion 5 a of 11 is fitted and fixed to the rotating shaft 10. A disc spring 13 having a non-linear spring characteristic is provided between the bottom surface of the recess of the front bracket 4 and the outer ring end surface of the bearing 8. Therefore, the disk 12 includes the bearing 8 and the rotary shaft 10.
A constant load of the disc spring 13 is applied via the
0 is braked by the frictional sliding resistance force of the disc 12 and the brake shoe 11.

In such a motor 1 with a brake, a disc spring 12 having a non-linear spring characteristic is provided, and a braking force of the rotary shaft 10 is obtained within a constant load region of the non-linear spring characteristic of the disc spring 13. As a result, it is possible to reduce the processing labor for increasing the dimensional accuracy of each component, and to suppress the variation in the braking force due to the variation in the dimensional accuracy. However, it suffices if the preload is such that rattling of the bearing 8 is eliminated, but in order to increase the braking force of the rotating shaft 10 by design, the constant load of the disc spring 13 must be increased, and the durability of the bearing 8 is improved. There may be a case where the structure of the disc spring 13 must be redesigned in a place where it is not damaged.

Further, since the electric motor with brake 1 constitutes a mechanical brake consisting of the brake shoe 11, the disc 12, and the disc spring 13, the kinetic energy of the inertial load acting on the rotary shaft 10 of the electric motor with brake 1 is provided. Must be absorbed by frictional engagement between the brake shoe 11 and the disk 12, and the amount of displacement of the disc spring 13 also decreases due to the wear of the brake shoe 11 over time. The electric motor 1 having such a mechanical brake requires troublesome maintenance and inspection.

In view of these problems, there has been proposed an electric motor having a gap type brake composed of a pair of permanent magnets (see Japanese Patent Laid-Open No. 61-154475). The air gap brake is composed of a pair of disk-shaped permanent magnets magnetized alternately in the circumferential direction N and S. One permanent magnet is fixed to the bracket of the electric motor, and the other permanent magnet is mounted to the rotating shaft. .. Therefore, the braking force of the air gap brake can be set by the magnetic force of the permanent magnets and the size of the air gap between the pair of permanent magnets. No maintenance is required.

[0007]

However, in an electric motor with a brake having a gap type brake composed of a pair of permanent magnets, when the permanent magnets face each other with different polarities, a braking torque for braking or holding the rotating shaft stationary. But get
When the permanent magnets face each other with the same pole, the repulsive force acts and the braking torque pulsates. Therefore, not only a stable braking action cannot be obtained, but also when such an action is repeated, there is a problem that the durability of the driven device is impaired.

In general, in an electric motor, in order to absorb a machining error of a component, to absorb a displacement of a rotary shaft due to thermal expansion, and further to prevent creep on the bearing outer ring side, FIG. A wave washer or the like is incorporated between the bracket and the end surface of the bearing outer ring at the position where the disc spring 13 is formed. Therefore, the size of the air gap between the pair of assembled permanent magnets is likely to vary, and this size must be finely adjusted to make the braking torque of the air gap brake constant, which causes a problem of poor assembly time and poor productivity. is there. An object of the present invention is to provide an air gap type brake that can eliminate such problems and obtain a stable braking action, and an electric motor with a brake that can easily install the air gap type brake and can improve productivity. To do.

[0009]

In order to achieve such an object, the hysteresis brake of the present invention has a multi-polar permanent magnet in which an even number of N and S poles are alternately arranged in the circumferential direction and have different polarities. And a yoke forming a magnetic circuit of the permanent magnet while the permanent magnet is fixed, and a hysteresis plate facing the permanent magnet with a predetermined gap,
In a hysteresis brake including a non-magnetic material hub to which the hysteresis plate is fixed, the yoke is supported on a rotating shaft via a bearing and fixed to a fixing member, and the yoke is mounted on the rotating shaft. By adopting a structure in which the boss end surface of the hub abuts on the inner ring side end surface of the bearing,
The gap was formed between the permanent magnet and the hysteresis plate.

Further, in such a hysteresis brake, when the rotary shaft is displaced in the axial direction due to thermal expansion or the like, the hysteresis plate is separated from the permanent magnet and the gap is increased to reduce the braking torque. The hub may be integrally connected to the rotary shaft only in the rotational direction by making the center hole non-circular and the outer peripheral surface of the fitting portion of the hub of the rotary shaft non-circular.

Furthermore, in order to inexpensively provide such a hysteresis brake that can obtain such stable braking torque, the magnitude of the braking torque and the design conditions required for equipment to which this type of hysteresis brake is mounted are set. The hysteresis plate may be manufactured by subjecting a medium / high carbon steel material to a heat treatment.

On the other hand, when such a hysteresis brake is mounted on an electric motor, if the end face of the hub boss is brought into contact with the end face of the bearing for supporting the rotation shaft on the bracket, the end face of the bearing becomes the hysteresis plate. Since the space between the permanent magnet and the permanent magnet is formed, the electric motor with a brake that can obtain a stable braking torque can be easily assembled.

[0013]

In the hysteresis brake, since the hysteresis plate rotates in the magnetic field of the permanent magnet, the kinetic energy due to the inertial load on the rotating shaft is absorbed by the hysteresis energy, and stable braking torque characteristics without pulsation can be obtained. Further, in the electric motor with a brake provided with such a hysteresis brake, when the electric motor is stopped, the rotating shaft supported by the bracket via the bearing inertially rotates, but the rotating shaft is braked without pulsating by the hysteresis brake.

[0014]

1 to 4 show a hysteresis brake and an electric motor with a brake according to an embodiment of the present invention.
Is a cross-sectional view of the rear side of the motor with a brake equipped with a hysteresis brake, FIG. 2 is a front view of the hysteresis brake corresponding to the side view taken along the line II-II of FIG. 1, and FIG. 3 is III of FIG.
FIG. 4 is a plan view of the hysteresis brake corresponding to a side view taken along line III-III, and FIG.

The brake-equipped electric motor 14 is composed of an electric motor 15 and a hysteresis brake 17 mounted on a rotary shaft 16 protruding from the rear bracket 5 of the electric motor 15. Since the electric motor 15 has substantially the same configuration as the electric motor 1 of FIG. 7, the detailed description will be omitted by using the reference numerals used in FIG. 7. Rotating shaft 16 of electric motor 15
Protrudes from the shaft hole of the rear bracket 5, and the hysteresis brake 17 is attached to the outside of the protruding extension 16a.

The hysteresis brake 17 has a rotary shaft 16
An inductor is fitted on the extended portion 16a of the disk through a bearing 18, and the inductor has a disk-shaped multipolar permanent magnet 19 made of a rare earth magnet having N and S poles alternately arranged in the circumferential direction, The permanent magnet 19 is fixed to the permanent magnet 19 and a disk-shaped yoke 20 that constitutes a magnetic circuit of the permanent magnet 19 is provided.
Are screwed to the bracket 5. Reference numeral 20a is
It is a screw hole into which a mounting screw (not shown) is inserted.

The inductor of the hysteresis brake 17 is a hysteresis plate 21 made of a semi-hard magnet facing the magnetic pole surface of the permanent magnet 19 with a predetermined space S (size of about 1 mm), and the hysteresis plate 21. A hub 22 made of a non-magnetic material made of an aluminum material or a synthetic resin material to which 21 is fixed is provided. And is fixed to the extension 16a of the rotary shaft 16 with the screw 23.

In the brake-equipped electric motor 14 having such a structure, since the hysteresis plate 21 is rotating within the magnetic field of the permanent magnet 19, when the electric motor 15 is stopped, the rotating shaft 16 is rotated.
Inertially rotates, but this kinetic energy is absorbed by hysteresis energy, and the rotating shaft 16 is quickly braked and stopped. Further, even if a light load acts on a driven device (not shown) mounted on the electric motor 15 and the rotating shaft 16 tries to rotate, the rotating shaft 16 does not have the hysteresis brake 17.
It is held stationary by.

FIG. 5 shows a second embodiment of the present invention and is a rear side view of an electric motor with a brake equipped with a hysteresis brake. The same components as those of the brake-equipped electric motor 14 described above are designated by the same reference numerals, and detailed description thereof will be omitted. The brake-equipped electric motor 24 shown in this drawing corresponds to the rear bracket 2 of the electric motor 25.
A bearing 9 is fitted to the outside of 6 so as to project. Then, by fitting a central hole side concave portion as a spigot portion formed on the yoke 28 of the hysteresis brake 27 into the protruding portion of the bearing 9 and fixing the yoke 28 to the bracket 26, the outer ring of the bearing 9 is fixed to these brackets. 26 and 28
It is fixed at.

Further, after the end surface of the boss portion 22a of the hub 22 is brought into contact with the end surface of the bearing 9 on the inner ring side, the hub 22 is fixed to the extension portion 16a of the rotary shaft 16 by the screw 23, whereby the permanent magnet 19 and A space S with the hysteresis plate 21 is formed. Such a motor with a brake 25 has the same effect as that of the motor with a brake 14, and the bearing 18 shown in FIG. 1 is not required, so that the motor with a brake 25 can be provided at a low cost.

FIG. 6 shows a third embodiment of the present invention and is a rear side sectional view of a brake-equipped electric motor equipped with a hysteresis brake. The same components as those of the brake-equipped electric motor 14 described above are designated by the same reference numerals, and detailed description thereof will be omitted. In the electric motor 29 with a brake shown in this drawing, the tip of an extension 31a of a rotary shaft 31 protruding from the bracket 5 of the electric motor 30 is formed into a non-circular D-shaped portion 31b having a D-shape. Then, the shaft hole 33a of the hub 33 of the hysteresis brake 32 is inserted into the rotary shaft 31
The D-shaped portion 31b has the same shape as the D-shaped portion 31b.

The end wall surface 34 of the D-shaped portion 31b formed on the extension 31a of the rotary shaft 31 and the shaft hole 3 of the hub 33 are formed.
Between the side surface 35 of 3a (exaggeratedly shown)
A gap L is formed, and the hub 33 is integrally connected to the rotation shaft 31 in the rotation direction. Reference numeral 36 is a snap ring for preventing the hub 33 from coming off, and is engaged with the extension portion 31 a of the rotary shaft 31. In addition, the hysteresis plate 21 of the hysteresis brake 32 is formed of a disk obtained by heat-treating a medium / high carbon steel material such as S45C.
This hysteresis plate 21 is obtained by, for example, quenching an S45C steel plate at a quenching temperature of about 850 degrees for about 1 hour, then tempering it at a tempering temperature of about 180 degrees for about 2 hours, and performing surface treatment after tempering. It is manufactured.

In such a carbon steel material hysteresis plate, unlike the hysteresis plate made of a semi-hard magnet, the eddy current is large and the braking torque also increases in proportion to the increase in the slip rotation speed, but the internal structure of the hysteresis plate itself. However, since the magnetic resistance is smaller than that of the semi-hard magnet, the magnetic attraction force of the hysteresis plate by the permanent magnet is increased. Therefore, even if the axial displacement acting on the rotating shaft of the electric motor is large, the air gap can be kept constant by the magnetic attraction force.

In this embodiment, the hub 33 is retained on the rotary shaft 31 by the bearing 18 and the snap ring 36, but a minute gap is formed between the hub 33 and the snap ring 36. The hub 33 may be integrally connected to the rotary shaft 31 only in the rotation direction. With this structure,
Since the magnetic attraction force of the permanent magnet 19 does not act on the rotary shaft 31, the rotary shaft 31 of the electric motor 30 is displaceable in the axial direction. Further, although the D-shaped hole 31b formed in the extension 31a of the rotating shaft 31 and the shaft hole 33a of the hub 33 having the D-shape are fitted, a spline groove is formed in the extending portion 31a of the rotating shaft 31. The design can be changed by spline-fitting the shaft hole 33a of the hub 33 into the groove.

The brake-equipped electric motor 29 having such a structure has the same effect as that of the brake-equipped electric motor 14, but has a D-shaped portion 31b of the rotary shaft 31 and a D-shaped shaft hole 33a of the hub 33. The hysteresis plate 21 fixed to the hub 33 is not separated from the permanent magnet 19 due to the displacement of the rotating shaft 31. Although the hysteresis brake is externally attached to the extension 31a of the rotary shaft 31 in this embodiment, the hysteresis brake may be incorporated in the electric motor.

[0026]

As described above, in the hysteresis brake and the electric motor with brake of the present invention, the hysteresis brake is a multi-polar permanent magnet in which the polarities are alternately arranged in the circumferential direction and the N and S poles are arranged in an even number. A yoke which is fixed to the permanent magnet and constitutes a magnetic circuit of the permanent magnet, a hysteresis plate facing the permanent magnet with a predetermined gap, and a hub made of a non-magnetic material to which the hysteresis plate is fixed. In the hysteresis brake provided with, the yoke is supported on a rotating shaft via a bearing and fixed to a fixed member, and the boss end surface of the hub mounted on the rotating shaft is on the inner ring side end surface of the bearing. Since the abutting structure is employed, unlike the air gap brake composed of a pair of permanent magnet pieces, a stable braking action can be obtained without pulsation of braking torque being observed. In addition, since the predetermined gap between the permanent magnet and the hysteresis plate is formed by abutting the end face of the hub boss against the end face of the bearing on the inner ring side, gap adjustment is easy.

Further, by making the center hole of the hub non-circular and the outer peripheral surface of the fitting portion of the hub of the rotary shaft non-circular, the hub is integrally connected to the rotary shaft only in the rotational direction. Therefore, even if the rotating shaft is displaced, the hub will not be displaced in the axial direction. Therefore, since the gap between the permanent magnet and the hysteresis plate does not change, a stable braking action can be obtained at all times.

Furthermore, since the hysteresis plate manufactured by quenching the medium / high carbon steel is used, the hysteresis brake can be provided at low cost, and the magnetic attraction force of the hysteresis plate by the permanent magnet is increased. The axial displacement of the rotary shaft, which is the direction opposite to the direction in which the force acts, can be prevented by the magnetic attraction force of the permanent magnet that magnetically attracts the hysteresis plate fixed to the hub. Therefore, the gap between the permanent magnet and the hysteresis plate does not change due to the displacement of the rotating shaft, so that a stable braking action can always be obtained.

On the other hand, the motor with a brake has a stator core fixed to a bracket, a rotor core arranged in a field space of the stator core, and the rotor core fixed to the bracket. , A non-magnetic material hub fixed to the rotary shaft with a hysteresis plate fixed thereto, and facing the hysteresis plate with a predetermined gap, and the polarities are alternately different in the circumferential direction. Each NS
A multi-polar permanent magnet having an even number of poles arranged, and a yoke fixed to the permanent magnet and constituting a magnetic circuit of the permanent magnet and fixed to the bracket, the boss end surface of the hub is Since the bearing is in contact with the inner ring side end surface of the bearing, unlike the electric motor with a brake including the air gap brake composed of a pair of permanent magnet pieces, stable braking action can be obtained without pulsation of braking torque. Be done.

Further, by making the center hole of the hub non-circular and the outer peripheral surface of the fitting portion of the hub of the rotary shaft non-circular, the hub is integrally connected to the rotary shaft only in the rotational direction.
The hub is not displaced in the axial direction due to the displacement of the rotating shaft. Therefore, since the gap between the permanent magnet and the hysteresis plate does not change, a stable braking action can always be obtained. Further, the hysteresis brake can be easily attached to the electric motor, and the productivity of the electric motor with a brake can be improved.

[Brief description of drawings]

FIG. 1 is a rear side sectional view of a brake-equipped electric motor equipped with a hysteresis brake, which is a first embodiment of the present invention.

FIG. 2 is a front view of the hysteresis brake corresponding to the side view taken along the line II-II in FIG.

FIG. 3 is a plan view of the hysteresis brake corresponding to the side view taken along the line III-III in FIG.

FIG. 4 is a cross-sectional view of a main part of a hysteresis brake.

FIG. 5 is a rear side sectional view of a brake-equipped electric motor equipped with a hysteresis brake, which is a second embodiment of the present invention.

FIG. 6 is a rear side sectional view of a brake-equipped electric motor equipped with a hysteresis brake, which is a third embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a conventional electric motor with a brake.

[Explanation of symbols]

 5 Bracket (on the rear side) 16 Rotating shaft 19 Permanent magnet 20 Yoke 21 Hysteresis plate 22 Hub 22a Boss

Claims (5)

[Claims] 1. A multi-polar permanent magnet in which the N and S poles are arranged in an even number in the circumferential direction and the polarities are alternately different, and a yoke which is fixed to the permanent magnet and constitutes a magnetic circuit of the permanent magnet. In a hysteresis brake including a hysteresis plate facing the permanent magnet with a predetermined gap, and a hub made of a non-magnetic material to which the hysteresis plate is fixed, the yoke has a bearing on a rotating shaft. A hysteresis brake having a structure in which an end surface of a boss portion of the hub mounted on the rotating shaft is supported and fixed to a fixing member and abuts on an end surface of the bearing on the inner ring side. 2. The hub is integrally formed with the rotary shaft only in the rotational direction by making the shaft hole of the hub non-circular and the outer peripheral surface of the fitting portion of the hub of the rotary shaft non-circular. The hysteresis brake according to claim 1, wherein the hysteresis brake is connected. 3. The hysteresis brake according to claim 1, wherein the hysteresis plate is manufactured by heat-treating a medium / high carbon steel material. 4. A stator core fixed to a bracket,
A rotor core arranged in the field space of the stator core, a rotary shaft to which the rotor core is fixed and which is supported by the bracket through a bearing, and a hysteresis plate which is fixed to the rotary shaft. A non-magnetic hub, a multi-polar permanent magnet that is opposed to the hysteresis plate with a predetermined gap, and has an even number of N and S poles alternately arranged in the circumferential direction, and the permanent magnet. A brake having a structure in which a magnet is fixed and a yoke that constitutes a magnetic circuit of this permanent magnet and is fixed to the bracket is provided, and an end surface of the hub boss portion is in contact with an end surface of the bearing on the inner ring side. With electric motor. 5. The hub is integrally formed with the rotary shaft only in the rotational direction by making the shaft hole of the hub non-circular and the outer peripheral surface of the fitting portion of the hub of the rotary shaft non-circular. The electric motor with a brake according to claim 4, wherein the electric motor with a brake is connected.