JP7236870B2 - Excitation actuated brake - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation brake that brakes a rotating member or a moving member or maintains the braked state.

2. Description of the Related Art Conventionally, an electromagnetically actuated brake (hereinafter simply referred to as an electromagnetic brake) constitutes a braking device and a brake holding device, and is used as a safety device in various fields. Conventional electromagnetic brakes of this type often have a field core having an exciting coil fixed to a support so as not to move, and an armature provided on a braking shaft to be braked. In this electromagnetic brake, the excitation coil is energized and the armature is magnetically attracted to the field core, thereby braking the rotation of the braking shaft.

The friction torque T generated in this type of electromagnetic brake is obtained by a formula of friction coefficient μ×total axial pressure P×effective radius R of friction surfaces×number N of friction surfaces. This torque value corresponds to the B (magnetic flux density)-H (magnetic field strength) characteristic of the iron core. Therefore, the braking torque of the electromagnetic brake increases as the voltage applied to the exciting coil increases, as indicated by the dashed line and the two-dot chain line in FIG.

In FIG. 12, the dashed line indicates the operating characteristics of an electromagnetic brake configured so that the braking torque is relatively low (hereinafter simply referred to as a low-torque electromagnetic brake), and the two-dot chain line in FIG. 1 shows the operating characteristics of an electromagnetic brake (hereinafter simply referred to as a high-torque electromagnetic brake) configured to increase the torque.
Since the high-torque electromagnetic brake can have a larger magnetic attraction force than the low-torque electromagnetic brake, high braking torque can be obtained. Also, as can be seen from FIG. 12, the minimum braking torque of the high-torque electromagnetic brake is greater than the minimum braking torque of the low-torque electromagnetic brake.

On the other hand, as a conventional electromagnetic brake, there is one described in Patent Document 1, for example. The electromagnetic brake disclosed in Patent Document 1 has first and second armatures magnetically attracted to a field core. Among these armatures, the first armature is supported by the braking shaft via a plurality of leaf springs with relatively weak spring force, and the second armature has a plurality of leaf springs with relatively strong spring force. It is supported by the braking shaft through

According to this conventional electromagnetic brake, when the current flowing through the exciting coil is relatively small, the first armature is magnetically attracted to the field core and a relatively small braking force is generated. When the current flowing through the excitation coil is relatively large, the first armature and the second armature are magnetically attracted to the field core, increasing the braking force. Therefore, it is possible to increase the difference between the minimum braking torque and the maximum braking torque.

Japanese Patent Application Laid-Open No. 2005-28510

Conventional electromagnetic brakes are required to have the ability to rotate the braking shaft when the minimum braking torque is generated, and to stop the braking shaft completely with a large maximum braking torque. there is something In order to meet this demand, it is necessary to use a high-torque electromagnetic brake in order to obtain a large maximum braking torque. However, with conventional high-torque electromagnetic brakes, the minimum braking torque is greater than the minimum braking torque of the low-torque electromagnetic brakes, making it difficult for the braking shaft to rotate when the minimum braking torque is generated. We were unable to comply with the above request.

Such a problem can be solved to some extent by using an electromagnetic brake capable of increasing the difference between the minimum braking torque and the maximum braking torque, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-200012. However, the electromagnetic brake disclosed in Patent Document 1 requires a plurality of leaf springs with different spring forces in order to individually support the two armatures. A problem arises.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an excitation operated brake which is capable of increasing the difference between minimum braking torque and maximum braking torque and which has a simple structure.

In order to achieve this object, an electromagnetically actuated brake according to the present invention includes a braking shaft as a member to be braked, a hollow portion formed in an annular shape, the braking shaft passing through a hollow portion in a loosely fitted state, and a shaft of the braking shaft. a field core having a magnetic pole surface formed at one end in a direction; an exciting coil provided in the field core; and a plurality of armatures mounted so as to be movable in the axial direction and to rotate integrally with the braking shaft, wherein the number of armatures magnetically attracted to the field core is determined by the power supplied to the excitation coil. It varies according to size.

In the present invention, the excitation-operated brake may further include a spring member that biases the plurality of armatures toward the field core.

In the electromagnetically actuated brake according to the present invention, the plurality of armatures may be made of the same material and have the same shape.

In the present invention, when the power supplied to the exciting coil (for example, the current flowing through the exciting coil) is relatively small, the inner armature closest to the field core among the plurality of armatures is magnetically attracted. An armature is magnetically attracted to the magnetic pole faces of the field core. The braking shaft is braked by the armature being attracted to the magnetic pole face in this way. In this case, it functions substantially as a low-torque electromagnetic brake, and a relatively small minimum braking torque is obtained.

As the current supplied to the excitation coil increases, the armature positioned outside (opposite to the field core) from the inner armature also becomes magnetically attracted to the field core. This outer armature is sucked into the field core, thereby pushing the inner armature towards the field core. As a result, the inner armature is urged by the outer armature and strongly pressed against the magnetic pole face, increasing the braking force.

In this case, it functions substantially as a high-torque electromagnetic brake, and a maximum braking torque equivalent to that of the high-torque electromagnetic brake can be obtained.
Since the member that axially movably supports the plurality of armatures is the braking shaft, no dedicated parts are required to support the plurality of armatures.
Therefore, according to the present invention, it is possible to provide an excitation actuated brake which is capable of increasing the difference between the minimum braking torque and the maximum braking torque and which has a simple structure.

1 is a front view of an excitation actuated brake according to the present invention; FIG. FIG. 4 is a rear view of an excitation-operated brake according to the present invention; 3 is a cross-sectional view taken along line III-III in FIG. 2; FIG. It is a front view of a field core. It is a rear view of a field core. FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5; It is a sectional view of a braking shaft and an armature. FIG. 4 is a cross-sectional view of a main part showing the state of magnetic flux when a low current is supplied; FIG. 4 is a cross-sectional view of a main part showing the state of magnetic flux when a high current is supplied; FIG. 11 is a cross-sectional view showing a modification of a plurality of armatures; FIG. 11 is a cross-sectional view showing a modification of a plurality of armatures; 4 is a graph showing the relationship between braking torque and voltage of an excitation-operated brake;

An embodiment of an excitation actuated brake according to the present invention will be described in detail below with reference to FIGS. 1 to 9. FIG.
An electromagnetically actuated brake 1 (hereinafter simply referred to as an electromagnetic brake) 1 shown in FIG. system electromagnetic brake. The electromagnetic brake 1 includes a braking shaft 2, a field core assembly 3 through which the braking shaft 2 passes, a plurality of armatures 4, 4 arranged at one end of the field core assembly 3, and the plurality of armatures. A spring member 5 (see FIG. 3) for biasing the field core assembly 3 is provided. In the following description of the configuration of the electromagnetic brake 1, one end side where the plurality of armatures 4, 4 are located will be referred to as the front side for the sake of convenience.

The field core assembly 3, as shown in FIG. 3, is formed by assembling various parts to a bottomed cylindrical field core 11 located on the outermost side in FIG. The field core 11 is formed in an annular shape and has a hollow portion through which the braking shaft 2 is loosely fitted. More specifically, as shown in FIGS. 3 to 6, the field core 11 includes a cylindrical inner cylindrical portion 12 positioned radially inward and an inner cylindrical portion 12 positioned on the same axis as the inner cylindrical portion 12. It has a cylindrical outer cylindrical portion 13 located radially outside of the portion 12 and an annular disk portion 14 connecting the front ends of the inner cylindrical portion 12 and the outer cylindrical portion 13 .

First and second sliding bearings 15 and 16 are provided on the inner peripheral portion of the inner cylindrical portion 12, as shown in FIG. The inner cylindrical portion 12 supports the brake shaft 2 rotatably and axially movably via the first and second sliding bearings 15 and 16 . The first and second plain bearings 15 and 16 are made of a non-magnetic material in order to prevent magnetic flux Φ passing through field core 11 from leaking to braking shaft 2 .
Of the first and second slide bearings 15 and 16, the first slide bearing 15 located on the rear side comes into contact with the retainer ring 17 attached to the brake shaft 2, causing the brake shaft 2 to move forward. is regulated.

An annular core plate 18 is fitted and fixed to the rear end portion of the outer peripheral surface of the inner cylindrical portion 12 . A gap S for magnetic isolation is formed between the outer peripheral surface of the core plate 18 and the inner peripheral surface of the outer cylindrical portion 13 .
The outer cylindrical portion 13 is formed to protrude rearward from the inner cylindrical portion 12 . A mounting flange 19 extending radially outward is integrally formed at the rear end of the outer cylindrical portion 13 .

The disc portion 14 is positioned at one end (front end) of the field core 11 in the axial direction of the braking shaft 2 . The front surface of the disk portion 14 is the magnetic pole surface 21 of the field core 11 . Of the plurality of armatures 4 , 4 to be described later, the inner armature 4 A adjacent to the field core 11 is pressed against the magnetic pole face 21 by the spring force of the spring member 5 . The disc portion 14 cooperates with the inner cylindrical portion 12 and the outer cylindrical portion 13 to form an annular groove 22 . An exciting coil 23 and a bobbin 24 are accommodated in the annular groove 22 .
The excitation coil 23 is connected to a power supply (not shown) via a power supply cable 25 (see FIGS. 1 and 2), and is excited by power supply from the power supply to generate a magnetic flux Φ. The power supply cable 25 is led out of the field core 11 through a through hole 26 (see FIG. 6) of the outer cylindrical portion 13 .

The disc portion 14 of the field core 11 has a magnetic isolation portion 31 that makes it difficult for the magnetic flux Φ to pass through the plurality of armatures 4, 4 so that the magnetic flux Φ generated by the excitation coil 23 being energized detours. are doing.
As shown in FIG. 3, the magnetic isolation section 31 includes a groove 32 that opens to the front surface of the disk section 14 . As shown in FIG. 4, the groove 32 is formed in an annular shape when viewed from the front side, and divides the front surface (magnetic pole surface 21) of the disk portion 14 into an inner side and an outer side in the radial direction. A flat first magnetic pole surface 21A is formed on the front surface of the disc portion 14 and radially inside the groove 32 . A flat second magnetic pole surface 21B is formed on the front surface of the disc portion 14 and radially outside the groove 32 . The first magnetic pole surface 21A and the second magnetic pole surface 21B are formed at the same position in the axial direction of the braking shaft 2 .

A friction plate 33 is provided in the groove 32 as shown in FIG. The friction plate 33 is formed in an annular shape and fixedly fitted in the groove 32 . Further, the friction plate 33 is configured to slightly protrude from the first and second magnetic pole faces 21A and 21B when attached to the groove 32. As shown in FIG.
A plurality of slits 34 are formed in the groove bottom 32a of the groove 32 (see FIG. 6). In this embodiment, three slits 34 are formed in groove 32 . The opening shape of the slit 34 is an arcuate ellipse around the axis of the braking shaft 2 . The three slits 34 are formed at positions dividing the disk portion 14 into three equal parts in the circumferential direction, and penetrate the groove bottom 32a in the front-rear direction. By forming the three slits 34 in the groove 32 , a bridge portion 35 is formed between the slits 34 at the groove bottom 32 a of the groove 32 .

As shown in FIG. 7, the plurality of armatures 4, 4 are each formed in a disc shape, and extend toward the first and second magnetic pole faces 21A, 21B of the field core 11 in the axial direction of the braking shaft 2. They are arranged side by side. The broken position in FIG. 7 is the position indicated by the VII--VII line in FIG. The plurality of armatures 4, 4 according to this embodiment are made of the same magnetic material and have the same shape. The same shape here means that the thickness and outer diameter are the same, and the outer shape is also the same. In this embodiment, two armatures 4 are used in an overlapping state. Hereinafter, for convenience, one of the two armatures 4, 4 near the field core 11 will be referred to as the inner armature 4A, and the other armature 4 will be referred to as the outer armature 4B.
The inner armature 4A and the outer armature 4B according to this embodiment are hardened after being formed to their final shape.

As shown in FIG. 7, the axial center portions of the inner and outer armatures 4A and 4B are fitted to the coupling portion 2a having the pair of cut surfaces 36 of the braking shaft 2 so as to be movable in the axial direction of the braking shaft 2. there is Therefore, the inner and outer armatures 4A and 4B are attached to the brake shaft 2 so as to be axially movable and to rotate together with the brake shaft 2. As shown in FIG.
The outer armature 4B is urged rearward with respect to the braking shaft 2 by a spring member 5 provided between it and a spring seat 41 on the front end side of the braking shaft 2, as shown in FIG.

The outer armature 4B pushed rearward by the spring member 5 in this way contacts the front surface of the inner armature 4A and pushes the inner armature 4A toward the field core 11 . In this embodiment, the inner armature 4A corresponds to the "other armature" in the present invention, and the outer armature 4B corresponds to the "armature having another armature between the field core" in the present invention. Equivalent to.
The spring member 5 according to this embodiment is composed of a compression coil spring. The spring seat 41 is formed of a ring through which the braking shaft 2 penetrates, and overlaps the snap ring 42 engaged with the braking shaft 2 from the rear side.

In the electromagnetic brake 1 constructed as described above, the inner armature 4A rotates in contact with the friction plate 33 of the field core 11, thereby applying frictional resistance to the braking shaft 2 and braking the braking shaft 2. be. When the excitation coil 23 is not energized, the inner armature 4A is pressed against the friction plate 33 only by the spring force of the spring member 5. As shown in FIG. In this electromagnetic brake 1, the inner armature 4A is thus pressed against the friction plate 33 only by the spring force of the spring member 5, thereby obtaining the minimum braking torque. Therefore, the minimum braking torque of the electromagnetic brake 1 is smaller than the minimum braking torque obtained by energizing the exciting coil 23 .

When the excitation coil 23 is energized to generate a magnetic flux Φ, and this magnetic flux Φ passes through the inner armature 4A, a magnetic attractive force acts on the inner armature 4A, and the inner armature 4A is assisted by the magnetic attractive force. It comes to be pressed against the friction plate 33 . Therefore, the frictional resistance generated at the contact portion between the inner armature 4A and the friction plate 33 increases. At this time, the force that presses the inner armature 4A against the friction plate 33 changes according to the magnitude of the current (voltage) supplied to the excitation coil 23. FIG.

When the electric power supplied to the exciting coil 23 is relatively small (when a low current is supplied), the magnetic flux Φ avoids the demagnetizing portion 31 of the disk portion 14 and reaches the first and second It detours through the second pole faces 21A, 21B to the inner armature 4A. When the supplied power is small in this way, the magnetic flux Φ does not detour from the inner armature 4A to the outer armature 4B, or if it does, the detour is extremely small. Therefore, in this case, the electromagnetic brake 1 substantially functions as a low-torque electromagnetic brake.

When the power supplied to the excitation coil 23 is relatively large (when a high current is supplied), as shown in FIG. 9, the magnetic flux Φa that passes through the inner armature 4A and the outer armature 4B increases. . Then, the outer armature 4B is also attracted to the disc portion 14 by the magnetic attraction force, and the outer armature 4B pushes the inner armature 4A toward the field core 11. - 特許庁That is, the number of armatures 4 magnetically attracted to field core 11 varies according to the magnitude of power supplied to exciting coil 23 .

Therefore, the inner armature 4A is pushed by the outer armature 4B and strongly pressed against the magnetic pole surface 21 (friction plate 33), increasing the braking force. In this case, it functions substantially as a high-torque electromagnetic brake, and a maximum braking torque equivalent to that of the high-torque electromagnetic brake can be obtained.
In this electromagnetic brake 1, the member that axially movably supports the plurality of armatures 4, 4 is the braking shaft 2, so that no dedicated parts are required to support the plurality of armatures 4, 4. FIG.
Therefore, according to this embodiment, it is possible to provide an electromagnetic brake (excitation actuated brake) which can make a large difference between the minimum braking torque and the maximum braking torque and which has a simple structure.

The braking torque of the electromagnetic brake 1 changes as indicated by the solid line in FIG. 12 as the voltage applied to the excitation coil 23 changes. As shown in FIG. 12, in the electromagnetic brake 1 of this embodiment, when the current (voltage) value is low, it is possible to obtain a braking torque close to the minimum value of the braking torque of the low-torque electromagnetic brake. When the current (voltage) value increases, it is possible to obtain a braking torque that approximates the maximum value of the braking torque of the high-torque electromagnetic brake. Further, by adopting this embodiment, in the process of shifting from a low voltage state to a high voltage state, an operating characteristic is obtained in which the rate of increase in braking torque is higher than that of conventional low-torque electromagnetic brakes and high-torque electromagnetic brakes. I found out that I can. It should be noted that design values such as the number of turns of the excitation coil 23 of the electromagnetic brake 1 are different from those of the high-torque electromagnetic brake.

An electromagnetic brake 1 according to this embodiment includes a spring member 5 that biases a plurality of armatures 4, 4 toward a field core 11. As shown in FIG. Therefore, by changing the spring force of the spring member 5, it is possible to change the magnitude of the braking torque obtained when the exciting coil 23 is not excited. Therefore, it is possible to provide an electromagnetic brake with a wide adjustment range of the minimum braking torque.

The plurality of armatures 4, 4 of the electromagnetic brake 1 according to this embodiment are made of the same material and have the same shape. Therefore, parts can be shared, and the manufacturing cost can be reduced.

(Modified example of multiple armatures)
Multiple armatures may be configured as shown in FIGS.
The electromagnetic brake 1 shown in FIG. 10 includes an inner armature 4A, an outer armature 4B, and a central armature 4C sandwiched between the inner armature 4A and the outer armature 4B. Thus, when a plurality of armatures 4 are provided, the number of armatures 4 arranged in the axial direction of the braking shaft 2 is not limited to two, and may be three or more.

The inner armature 4A shown in FIG. 11 is formed thicker than the outer armature 4B. These inner armature 4A and outer armature 4B are formed so as to have the same configuration except that they differ in thickness.
By changing the number of armatures 4 or the thickness of some of the armatures 4 in this manner, the voltage and braking torque when the characteristics of the low-torque electromagnetic brake are changed to those of the high-torque electromagnetic brake during braking can be reduced. Since the rate of increase can be changed, it is possible to easily manufacture an electromagnetic brake having desired characteristics.

DESCRIPTION OF SYMBOLS 1... Electromagnetic brake (excitation operated brake), 2... Braking shaft, 3... Field core assembly, 4... Armature, 4A... Inner armature, 4B... Outer armature, 5... Spring member, 11... Field core, 21A... First magnetic pole face 21B... Second magnetic pole face 23... Exciting coil Φ, Φa... Magnetic flux.

Claims (4)

a braking shaft as a member to be braked;
a field core formed in an annular shape, the braking shaft passing through a hollow portion in a loose fit state, and a magnetic pole surface formed at one end portion in the axial direction of the braking shaft;
an exciting coil provided on the field core;
A plurality of field cores are arranged in the axial direction toward the magnetic pole surface of the field core and are arranged in an overlapping state , and are attached to the braking shaft so as to be movable in the axial direction and to rotate integrally with the braking shaft. an armature ;
a spring member that biases the plurality of armatures toward the field core;
The spring member is composed of a compression coil spring and configured to urge the plurality of armatures toward the field core with the braking shaft passed therethrough,
The number of armatures magnetically attracted to the field core varies according to the magnitude of power supplied to the excitation coil,
When the exciting coil is not excited, the armature near the field core among the plurality of armatures is brought into contact with the field core only by the spring force of the spring member to generate frictional resistance and obtain the minimum braking torque. An excitation actuated brake characterized by: The excitation actuated brake according to claim 1,
An excitation actuated brake, wherein the axial center portions of the plurality of armatures are fitted to the coupling portion having the cut surface of the braking shaft so as to be movable in the axial direction of the braking shaft. In the electromagnetically actuated brake according to claim 1 or claim 2,
The plurality of armatures include an inner armature that is close to the field core and produces frictional resistance at a contact portion with the field core, and an outer armature that is positioned between the inner armature and the field core. including
When the power supplied to the excitation coil is relatively small, the magnetic attraction force acts mainly on the inner armature,
When the power supplied to the excitation coil is relatively large, the magnetic attraction force also acts on the outer armature, and the inner armature is pushed by the outer armature to be strongly pressed against the magnetic pole surface, An excitation-operated brake characterized by increasing braking force . In the excitation actuated brake according to any one of claims 1 to 3 ,
An excitation-operated brake, wherein the plurality of armatures are made of the same material and have the same shape.

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