JP2023010011A - electromagnetic brake - Google Patents

Abstract

To compactly configure an electromagnetic brake having an overexcitation circuit while taking heat radiation into consideration.SOLUTION: In adopting a configuration for energizing a coil 2 through an overexcitation circuit 7 to excite a yoke 1, a substrate 7x, on which the overexcitation circuit 7 is mounted, is resin-molded on the yoke 1 together with the coil 2, so that the overexcitation circuit 7 is integrally formed with the yoke 1 to compactify the electromagnetic brake MB. By resin-molding the overexcitation circuit 7 on the yoke 1 together with the coil 2, a heat load received by the overexcitation circuit 7 can be reduced by heat radiation through a resin mold layer 8.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electromagnetic brake that supplies power through an overexcitation circuit.

The electromagnetic brake has a yoke, a coil that excites the yoke by receiving power from the outside through a power supply path, and braking means. There is known a brake that is provided with an overexcitation circuit that brings the brake into an overexcitation state, and that is configured to switch the ON/OFF state of the brake by the braking force of the braking means and the excitation force through the power supply path (for example, Patent document 1).

FIG. 8 shows an electromagnetic brake MB that performs substantially the same basic operation as that of Patent Document 1 described above.

This electromagnetic brake MB includes a yoke 1, a coil 2 provided on the yoke 1, and a coil spring 3 as a braking means. When de-energized, the armature 4 is moved by the coil spring 3 and the disk 6 is sandwiched between the side plate 5 and the braking force of the disk 6 is transmitted to the motor shaft 10, and when excited, the electromagnetic force is generated. By separating the armature 4 from the side plate 5 side and attracting it to the attracting surface 1a of the yoke 1, the braking state of the motor shaft 10 by the disk 6 is released.

At this time, an overexcitation circuit 7 as shown in FIG. 8 is externally attached in the middle of the energization path L to temporarily set the excitation of the yoke 1 to an overexcitation state, thereby increasing the excitation force at the time of initial movement when the brake is released. is increased to effectively drive the armature 4, and after the armature 4 is attracted to the yoke attraction surface 1a, the excitation is switched to normal excitation to appropriately maintain the attraction state.

Although Patent Document 1 uses a permanent magnet instead of a coil spring as a braking means, the basic operation is the same as that shown in FIG.

JP-A-9-273577

Conventionally, however, this type of overexcitation circuit 7 is externally attached to the yoke 1 as an overexcitation circuit component 70, as shown in FIGS. For this reason, when an electromagnetic brake as shown in FIG. Therefore, the electromagnetic brake MB cannot be made compact, and there are many restrictions on its assembly to a motor or the like.

Therefore, it can be considered as an effective means to integrally assemble the overexcitation circuit 7 in the electromagnetic brake MB. However, in this case, since this type of overexcitation circuit 7 is composed of electronic components, it is necessary to take appropriate measures in addition to the fact that it is susceptible to thermal and electromagnetic influences.

An object of the present invention is to realize a new electromagnetic brake based on such a point of view.

In order to achieve the above objects, the present invention takes the following measures.

That is, the electromagnetic brake of the present invention has a yoke, a coil that excites the yoke by receiving power from the outside through a power supply path, and braking means. An overexcitation circuit that temporarily overexcites the excitation, and is configured to switch the ON/OFF state of the brake by the braking force of the braking means and the excitation force through the power supply path, A substrate on which the overexcitation circuit is mounted is integrated with the yoke together with the coil by resin molding.

With this configuration, the overexcitation circuit can be integrally formed with the yoke, so that the electromagnetic brake can be made compact. Moreover, since the overexcitation circuit is equipped with electronic components, it is easily affected by heat. By resin-molding the yoke together with the coil, heat is released through the resin mold layer, thereby reducing the heat load on the overexcitation circuit. can be done.

It is preferable that the substrate is brought into close contact with the yoke via a heat dissipation sheet.

When continuous energization is performed to release the brake, heat dissipation from the resin mold layer alone is considered to be insufficient, so heat dissipation to the yoke is possible by attaching the substrate to the yoke via a heat dissipation sheet. As a result, in addition to the heat radiation from the resin mold layer, another heat radiation path with a higher heat radiation effect is secured, so that even if the substrate is integrated with the yoke, the influence of the heat load can be reduced more effectively.

In this case, it is preferable that the base is fixed to the yoke via a highly heat-conductive fastener.

The resin mold tends to lose its close contact with the yoke due to shrinkage of the resin during cooling. On the other hand, if a fastener with high heat conductivity as described above is used, it is possible to secure an appropriate tight contact state after resin molding and to newly form a heat radiation route through the fastener.

It is also preferable that the yoke is provided with a recess at the outer periphery of the coil, and the substrate is arranged in the recess.

When the overexcitation circuit is exposed to electromagnetic waves, the circuit functions as an antenna and receives the electromagnetic waves, which tends to adversely affect the function of the overexcitation circuit. On the other hand, by arranging the substrate with a concave portion provided on the outer circumference of the coil, it is possible to ensure a state in which the electromagnetic wave does not easily reach the substrate.

It is also preferable that an electromagnetic shielding wall is arranged between the coil and the substrate.

By arranging such an electromagnetic shielding wall, electromagnetic waves emitted from the coil winding portion (core portion) of the yoke can be shielded, and the influence of the electromagnetic waves on the overexcitation circuit can be reduced more effectively.

The present invention is particularly effective when the overexcitation circuit is configured to produce the normal excitation state by PWM control.

If a digital part is used in such an overexcitation circuit, it is particularly susceptible to electromagnetic waves, so countermeasures against electromagnetic waves are particularly effective.

According to the present invention described above, it is possible to provide a new electromagnetic brake which can be made compact by integrally assembling the overexcitation circuit to the yoke, and which is well adapted to the heat load.

1 is a perspective view showing a yoke portion of an electromagnetic brake according to one embodiment of the invention; FIG. FIG. 2 is a partial longitudinal sectional view of FIG. 1; Explanatory drawing of the overexcitation circuit which comprises the same embodiment. FIG. 3 is a partial cross-sectional view corresponding to FIG. 2 showing a modification of the present invention; FIG. 3 is a partial cross-sectional view corresponding to FIG. 2 showing a modification of the present invention; Explanatory drawing including the partial sectional view and top view corresponding to FIG. 2 which shows the modification of this invention. Explanatory drawing including the perspective view of the partial sectional drawing corresponding to FIG. 2 which shows the modification of this invention, and a coil bobbin. The figure which shows the structure of the conventional electromagnetic brake. The figure which shows the state which externally attached the overexcitation circuit to the conventional electromagnetic brake. The figure which shows the state which externally attached the overexcitation circuit to the conventional electromagnetic brake.

An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show the yoke 1 portion of the configuration of the electromagnetic brake shown in FIG. In describing the present embodiment, FIG. 8 is used as appropriate because it is a prerequisite configuration of the electromagnetic brake.

The yoke 1 is cylindrical with a bottom, has an annular gap 13 between an inner peripheral wall 11 and an outer peripheral wall 12, and has a through hole 14 inside the inner peripheral wall 11 for inserting a shaft. . A coil bobbin 20 wound with a coil 2 made of copper wire is accommodated in the annular gap 13 , and a rotating shaft is inserted through the through hole 14 . The coil bobbin 20 has an annular shape with a U-shaped opening on the outer peripheral side, and is made of a resin material.

The inner peripheral wall 11 and the outer peripheral wall 12 of the yoke 1, including the bottom wall 15, are composed of a core material and form a magnetic path through which magnetic flux passes. A magnetic path is connected through the armature 4 so that the armature 4 is attracted to the attraction surface 1a.

In order to supply power to the coil 2 from the outside, the outer wall 12 of the yoke 1 is provided with a lead-in portion 12a of the power supply path L, from which the wire 2a for power supply is led. The illustrated lead-in portion 12a uses a groove provided to avoid interference with other parts, but when such grooves are provided at a plurality of locations, an appropriate groove may be used. Alternatively, the outer wall 12 may be provided with only a hole without such a groove as a wiring lead-in portion.

An overexcitation circuit 7 shown in FIG. 3 is provided in the middle of the power supply path L. The overexcitation circuit 7 temporarily changes the excitation of the yoke 1 into an overexcitation state, thereby enabling appropriate initial movement of the armature 4 when the brake is released. and a switching timing control section 7b.

The voltage conversion unit 7a converts the input voltage into a lower output voltage and energizes the coil, and includes a PWM control circuit using an operational amplifier or the like. It creates a pseudo output voltage that is lower than the input voltage. Although 24V is converted to 5V in the illustrated example, the input voltage may be other than 24V, and the output voltage may be, for example, 5-12V. The voltage switching timing control unit 7b outputs the input voltage (for example, 24V) for a predetermined overexcitation period after the voltage is applied, and changes the voltage (for example, 5V) converted by the voltage conversion unit 7a after the overexcitation period. It performs a switching operation for switching to a voltage and outputting it, and is configured using the time constant of an RC circuit or the like.

Conventionally, the overexcitation circuit 7 was attached externally to the electromagnetic brake MB as shown in FIGS. 2, the substrate 7x on which the overexcitation circuit 7 is mounted is integrally incorporated into the yoke 1. As shown in FIG. At that time, since the overexcitation circuit 7 is susceptible to thermal influences and electromagnetic influences, it is devised to incorporate it into the yoke 1 .

Specifically, a portion of the outer peripheral wall 12 of the yoke 1 is recessed from the attraction surface 1a toward the bottom wall 15 to form a notch-shaped recess 16, and the bottom surface 16a of the recess 16 is provided with a heat dissipating material. A substrate 7x on which an overexcitation circuit 7 is mounted is mounted flatly on the yoke 1 so as to be in close contact with the yoke 1 through a heat dissipation sheet 17 using a general heat dissipation sheet.

In this state, the pair of input terminals of the overexcitation circuit 7 shown in FIG. A wiring 2a of 24∨ is connected, and a coil 2 accommodated in a coil bobbin 20 is connected to a pair of output terminals.

Then, in this state, a resin made of a general material used for molding is poured into the annular gap 13 and the concave portion 16, and the resin mold layer 8 (see FIG. 1(b)) formed by this is poured into the substrate 7x. is integrated with the yoke 1 together with the coil 2.

The electromagnetic brake MB assembled with the yoke 1 configured as described above urges the armature 4 shown in FIG. is operated to apply a voltage to the coil 2 to release the brake, the initial excitation force at the time of brake release is increased to effect the initial movement of the armature 4, and after the armature 4 is attracted to the attraction surface 1a, normal It operates as a non-excitation type electromagnetic brake that switches to excitation and appropriately maintains the attracting state of the armature 4 . Such switching of the operating state is repeated each time the 24V brake release command is turned ON/OFF.

As described above, in the electromagnetic brake of this embodiment, in adopting the configuration in which the yoke 1 is excited by energizing the coil 2 through the overexcitation circuit 7, the substrate 7x on which the overexcitation circuit 7 is mounted is mounted on the yoke 1 together with the coil 2. is resin molded. By integrally forming the overexcitation circuit 7 with the yoke 1 in this manner, the electromagnetic brake MB can be made compact. Moreover, since the overexcitation circuit 7 includes electronic components, it is easily affected by heat. The heat load that the overexcitation circuit 7 receives can be reduced.

Moreover, in the present embodiment, when continuous energization is performed for releasing the brake, the heat radiation effect may be weak only by the heat radiation from the resin mold layer 8. Therefore, the substrate 7x is connected to the yoke 1 ( Specifically, heat is dissipated to the yoke 1 by being brought into close contact with the bottom surface 16a) of the recess 16 provided in the yoke 1. In addition to the heat dissipating from the resin mold layer 8, there is another heat dissipating path with a higher heat dissipating effect. Therefore, even if the substrate 7x is provided integrally with the yoke 1, the influence of the heat load can be reduced more effectively.

In this embodiment, when the overexcitation circuit 7 is exposed to electromagnetic waves, the circuit functions as an antenna and receives the electromagnetic waves, which tends to adversely affect the function of the overexcitation circuit. Since the recess 16 is provided in the outer wall 12 and the substrate 7x is arranged in the recess 16, it is possible to ensure a state in which the electromagnetic wave does not easily reach the substrate 7x.

In particular, the overexcitation circuit 7 of the present embodiment creates a normal excitation state by PWM control and is easily affected by electromagnetic waves due to the use of digital components, so the above measures against electromagnetic waves are particularly effective.

Although one embodiment of the present invention has been described above, the specific configuration of each part is not limited to the above-described embodiment. Modifications of the present invention will be described below.

In the above embodiment, the recess 16 is provided in the outer peripheral wall 12 of the yoke 1 positioned on the outer circumference of the coil 2 and the base 7x is laid flat. A vertical hole-shaped concave portion 116 may be provided on the outer periphery 12 of the yoke 1 , and the substrate 7 x may be vertically inserted together with the heat radiation sheet 17 to be brought into close contact with the outer peripheral wall 12 of the yoke 1 .

Alternatively, as shown in FIG. 4(b), a recess 216 is provided in the bottom wall 15 of the yoke 1 below the coil 2 (coil bobbin 20), and the base 7x is placed in this recess 216 together with the heat radiation sheet 17 in a flat state. It may be installed in close contact with the

Alternatively, as shown in FIG. 4(c), a vertical hole-shaped concave portion 316 is provided in the inner peripheral wall 11 of the yoke 1 located on the inner periphery of the coil 2, and the substrate 7x is vertically inserted together with the heat radiation sheet 17. It may be brought into close contact with the inner peripheral wall 11 of the yoke 1 .

In either case, in addition to the effect of heat dissipation by the resin molding performed thereafter, the effect of heat dissipation to the yoke 1 from the portion in close contact with the yoke 1 can be expected.

Alternatively, as shown in FIG. 5(a), the base 7x may be fixed to the yoke 1 via a highly heat-conductive fastener 71 made of metal or the like. Specifically, a concave portion 16 is provided in the upper surface of the yoke 1 and the fastener 71 is press-fitted into the yoke 1, while a daruma hole 72 is provided in the base 7x and the large diameter portion of the daruma hole 72 is fitted to the head of the fastener 71. By passing it, it is laid flat on the yoke 1 together with the heat dissipation sheet 17, and then the base 7x is slid to move the fastener 71 relatively to the small diameter side, thereby preventing the base 7x from coming off.

In the case of resin molding, the shrinkage of the resin during cooling tends to impair the close contact of the substrate 7x with the yoke 1 via the heat dissipation sheet 17. It is possible to secure the close contact state of the substrate 7x to the yoke 1 and newly form a heat radiation route to the yoke 1 through the fastener 71.

In this case, one end of the substrate 7x may be brought into contact with and fixed to the side wall 16a of the recess 16, and the other end of the substrate 7x may be fixed at one point with a fastener. Further, as shown in FIG. 5(b), two or more points of the base 7x may be fixed to the yoke 1 with fasteners 71 in the form of screws. Alternatively, the fastener 71 of FIG. 5(a) and the fastener 71 of FIG. 6(a) may be combined.

Also, as shown in FIG. 6, it is effective to dispose an electromagnetic shielding wall 9 made of a material that shields electromagnetic waves between the coil 2 and the substrate 7x.

By arranging such an electromagnetic shielding wall 9, the electromagnetic wave shielding wall 9 shields the electromagnetic wave emitted from the winding portion (core portion) of the yoke 1 and the coil 2, and the electromagnetic wave to the overexcitation circuit 7 mounted on the substrate 7x. The influence can be effectively reduced. In this case, the base 7x may be laid flat in a recess 16 provided in the outer peripheral wall 12 of the yoke 1 as shown in FIG. 9 may be used to attach to its outer peripheral surface. In either case, it is effective to set the upper end of the electromagnetic shielding wall 9 at a position higher than the base 7x.

Alternatively, as shown in FIG. 6(c), when the base 7x is placed in close contact with the bottom wall 15 of the yoke 1 via the heat dissipation sheet 17, the base 7x is attached to the base 7x with a highly heat-conductive fastener 71 made of metal or the like. By fixing it to the bottom wall 15 of the yoke 1 through the yoke 1, the heat dissipation effect can be enhanced, and an electromagnetic wave blocking wall 9 wider than the base 7x is provided under the coil bobbin 20 to block electromagnetic waves, thereby taking measures against electromagnetic waves. be able to.

Alternatively, in the above-described embodiment, the substrate 7x is brought into close contact with the yoke 1 via the heat dissipation sheet 17. However, for example, when ON/OFF switching of the electromagnetic brake is infrequent and high heat dissipation is not required, the configuration shown in FIG. As shown in a) and (b), the coil bobbin 20 is provided with a collar portion 20a, and the collar portion 20a is placed in the recess 16 of the yoke 1. may be attached. Even in this case, heat dissipation from the resin mold layer 8 can be expected by resin molding after this.

However, if this is done, the coil bobbin 20 becomes deformed, which increases the amount of resin used during molding and the associated costs. It is preferable to mount the base 7x without changing the shape of the coil bobbin 20, such as the form. If there is a protrusion such as the flange 20a at the substrate bonding portion, it may cause winding defects (damage or disconnection) of the coil 2 .

Other configurations can also be modified in various ways without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1... Yoke 2... Coil 3... Braking means (coil spring)
DESCRIPTION OF SYMBOLS 7... Overexcitation circuit 8... Resin mold layer 9... Electromagnetic shielding wall 16... Recessed part 17... Heat radiation sheet 71... Fastener L... Power supply path

Claims (5)

a yoke; a coil that excites the yoke by receiving power from the outside through a power supply path; and braking means. and an overexcitation circuit configured to switch the ON/OFF state of the brake by the braking force of the braking means and the excitation force through the power supply path,
An electromagnetic brake, wherein a substrate on which said overexcitation circuit is mounted is integrated with said yoke together with said coil by resin molding. 2. The electromagnetic brake according to claim 1, wherein said base is brought into close contact with said yoke via a heat dissipation sheet. 3. The electromagnetic brake according to claim 2, wherein said base is fixed to said yoke via fasteners with high thermal conductivity. 4. The electromagnetic brake according to any one of claims 1 to 3, wherein said yoke is provided with a recess at an outer peripheral position of said coil, and said base is arranged in said recess. 5. The electromagnetic brake according to any one of claims 1 to 4, wherein an electromagnetic shielding wall is arranged between said coil and said substrate.

Images