JPH0317075Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an electromagnetic brake that is attached to the driven shaft of various electrical devices using an electric motor as a drive source. This invention relates to a middle drum type electromagnetic brake, which is also called a non-excitation operating type or an excitation release type, in which braking is performed by an electromagnetic force and released from braking by an electromagnetic force.

(Prior Art) Like hydraulic brakes used in automobiles, electromagnetic brakes can be broadly classified into two types: disc brakes and drum type brakes (or shoe type brakes). In the case of a disc type, it is necessary to brake the armature or both the armature and the disc and slide it in the axial direction when releasing the brake, so torque is transmitted via a spline, and the It is necessary to interpose a bearing between the rotating part that is dynamically connected to the rotary part and the stopping part for imparting braking force, as it is necessary to allow both to rotate relative to each other on the same axis. . In addition, in the case of drum type,
A pair of yokes equipped with brake shoes are arranged along the inner circumference of the drum, and a brake spring arranged between the yokes provides braking, and an electromagnet attached to one of the yokes is activated. I turned around and released the brake.

(Problems to be solved by the invention) In the conventional electromagnetic brakes mentioned above, although the disc type is compact overall, the accuracy of operation decreases due to the effect of backlash due to the provision of splines, while the drum type However, since the brake part and the electromagnet that drives the brake part are connected by a link mechanism or the like, there is a problem in that the overall size becomes large.

The "electromagnetic brake" disclosed in Japanese Patent Application No. 60-58992, which is related to the applicant's earlier application, was developed to solve the above-mentioned problems regarding drum-type electromagnetic brakes, and has achieved some results. However, since the structure was such that a single electromagnet attracted multiple armatures, the following drawbacks were observed.

In order to facilitate understanding, the structure of the invention of the prior application will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a side view of the electromagnetic brake according to the invention, and FIG. 4 is a sectional view taken along line A--A in FIG. 3. Reference numeral 1 in the drawings denotes a brake drum having a U-shaped cross section, the inner circumferential surface of its outer cylindrical portion serving as a braking surface, and the inner cylindrical portion serving as a hub to which a braked shaft is coupled. Reference numeral 2 denotes an annular electromagnet, which is composed of a yoke 3 having an annular groove on its outer periphery and opening outward, and a coil 4 housed in the annular groove. The peripheral surface of the rounded end becomes the magnetic pole surface.

6 is a lead wire, and 7 is an arc-shaped armature divided into four parts, each of which is attached to the fixing member 9 via a support member such as a leaf spring at one end, and is connected to the outer peripheral surface of the yoke 3 on the same circumference. The elasticity of the support member 8 allows it to swing freely in the radial direction in opposition to the magnetic pole surface.

A brake shoe 10 is screwed to the outer circumferential surface of the tip of each armature 7, and its outer circumferential surface is opposed to the inner circumferential surface of the drum 1, and is brought into pressure contact with the inner circumferential surface of the drum 1 to perform a braking action. However, in the case of light loads, the armature may be brought into direct pressure contact with the drum. A braking spring 12 is inserted into a hole formed in the radial direction in the magnetic pole surface, which is the circumferential surface of the yoke 3, and presses each brake shoe against the outer circumferential surface of the drum 1 via each armature.

If no current is supplied to coil 4,
Each of the armatures 7 is pushed open radially outward by the elastic force of the spring 12, and the brake shoe 1
0 is pressed against the inner peripheral surface of the drum 1, and braking is applied to the shaft to be braked via this drum. When current is supplied to the coil 4 in this state, a magnetic flux is formed as shown by the broken line, and the armature 7 is attracted toward the magnetic pole surface of the yoke 3 against the force of the spring 12, and each brake shoe is 10 is separated from the inner peripheral surface of the drum 1, and the braking is released.

The electromagnetic brake described above has considerably improved the deficiencies of the conventional drum type brake, but since it uses a single electromagnet to attract multiple armatures, the following deficiencies were observed.

1 If any one armature is attracted first (for example, such attraction may occur due to manufacturing errors in the spring), the electromagnetic gap in that part becomes smaller, and the magnetic resistance in that part decreases. Magnetic flux will concentrate and flow in that area.

(2) At this time, if we assume that magnetic saturation occurs in the electromagnet and the generation of magnetic flux is restricted, the magnetic flux flowing to other armatures will decrease, making it difficult to uniformly attract multiple armatures.

(3) In order to attract all the armatures reliably and evenly, the area of the yoke must be set so that even if the magnetic flux is concentrated in one armature, it will not cause magnetic saturation in other armatures, and the area of the yoke can be supplied with the necessary magnetic flux. If you try to make it sufficiently large and lower the magnetic flux density, the size and weight of the electromagnet will increase.

(Means for Solving the Problems) In consideration of the above problems, the present invention aims to prevent magnetic concentration on a part of the armature and to reduce the size of the electromagnet section.

A means to solve the problem is to set the saturation magnetic flux density of a portion of each armature near the mounting portion to be smaller than the saturation magnetic flux density of a portion near the brake shoe mounting portion that is distant from the armature mounting portion. This prevents extreme concentration and increase of magnetism, thereby making it possible to attract multiple armatures equally.

(Embodiment) FIGS. 1A to 1F are schematic perspective views showing an embodiment of the present invention, in which reference numeral 7 indicates an armature main body, 18 a mounting hole, and 19 a notch.

Figure 1 A has a short notch extending to the center in the longitudinal direction near the armature mounting hole 8, Figure B has a notch on both left and right sides in the longitudinal direction, and Figure C has a notch on one side. This figure shows an example. In FIG. 1D, the portion near the mounting hole is thin and the wall thickness increases as the portion goes farther away.

In FIG. 1E, the desired effect can be achieved even if the portions near the mounting holes on both left and right sides of the armature in the longitudinal direction are made thinner and have a "necked" shape.

FIGS. 1A to 1E show examples in which the cross-sectional area of the armature is changed. FIG. 1F shows a case where the saturation magnetic flux density is changed by selecting a material for the armature that is easily magnetically saturated, such as cast iron or high carbon steel sintered alloy.

FIG. 2 is a graph showing changes in the saturation magnetic flux density in the armature of the electromagnetic brake according to the present invention, where the horizontal axis represents the longitudinal position of the armature 7 and the vertical axis represents the saturation magnetic flux density.
When a notch is provided near the armature mounting hole 18 as shown in Figure 1B, as is clear from the figure, the saturation magnetic flux density is small at the position of the notch 19 and becomes large in other parts. .

Therefore, immediately after the coil 4 is energized, magnetic saturation occurs immediately at the notch 19, so that the magnetic resistance increases and the magnetic flux does not pass through the armature 7 above the saturation point. The part of the armature 7 where the brake shoe 10 is attached needs to be sufficiently attracted toward the yoke 3 against the brake spring 12, while the part near the part where the armature 7 is attached is fixed to the fixing member 9. There is no need to receive the action of suction force. Therefore, the first
As shown in Figures A to F, according to the present invention, the flow of magnetic flux is restricted in the vicinity of the armature attachment part that does not require suction force, while the flow of magnetic flux is restricted in the vicinity of the attachment part of the brake shoe 10 that requires suction force. Since sufficient magnetic flux flows, it is possible to reliably separate the brake shoe from the inner peripheral surface of the brake drum 1. In addition, Bf in Fig. 2 is brake shoe 10.
It shows the necessary and sufficient saturation magnetic flux density for the separation of .

(Effects) As shown in the embodiments of FIGS. 1A to 1F, by making the cross-sectional area near the armature attachment part smaller than other parts, not only can the object of the present invention be achieved, but also The cantilevered armature 7 can be easily bent, and a relatively small suction force is sufficient to suction the brake shoe mounting portion. Therefore, the attractive force of the electromagnet can be made small, the yoke and coil can be made smaller, and the concentration of magnetism on a part of the armature can be prevented and the electromagnet part can be made smaller. This will greatly contribute to both electromagnetic brake manufacturers and users.

[Brief explanation of the drawing]

1A to 1F are perspective views showing examples of the armature according to the present invention, FIG. 2 is a graph showing the distribution of saturation magnetic flux density when the armature shown in FIG. 1B is used, and FIG. FIG. 4 is a side view of a conventional drum type electromagnetic brake belonging to the same type, and is a side sectional view taken along line A--A in FIG. 3. Symbols in the drawing: 1: brake drum, 2: electromagnet, 3: yoke, 4: coil, 7: armature, 8: support member, 9: fixing member, 10: brake shoe, 12: braking spring, 18: mounting Hole, 1
9: Notch.

Claims (1)

[Claims for Utility Model Registration] (1) A brake drum whose inner circumferential surface of its outer edge defines a cylindrical inner circumferential surface; a single annular electromagnet directed toward the inner circumferential surface of the brake drum; arranged concentrically with the inner circumferential surface of the brake drum to perform braking by frictionally contacting the inner circumferential surface; and separated from the inner circumferential surface; a plurality of brake shoes for releasing braking; a plurality of armatures integrally connected radially inwardly of the brake shoes and arranged along the outer peripheral surface of the electromagnet while maintaining a required magnetic gap; In an excitation release type drum-type electromagnetic brake that has a braking spring that constantly presses the armature toward the brake drum and releases the braking by electromagnetic attraction force: Saturation of the portion of each armature near the mounting part By setting the magnetic flux density to be smaller than the saturation magnetic flux density in the area near the brake shoe attachment part away from the armature attachment part, excessive concentration and increase of magnetism is prevented, and thereby the plurality of armatures are evenly distributed. A drum type electromagnetic brake that is designed to be attracted to the (2) Utility Model Registration In the electromagnetic brake according to claim 1, the means for setting the saturation magnetic flux density is configured such that the cross-sectional area of the armature in a portion close to the armature mounting portion is set close to the brake shoe mounting portion. A drum type electromagnetic brake with a smaller cross-sectional area than the armature. (3) Utility Model Registration In the electromagnetic brake according to claim 1, the means for setting the saturation magnetic flux density is such that the material of the portion near the armature mounting portion is smaller than the material of the brake shoe mounting portion. Drum type electromagnetic brake made of material with low saturation magnetic flux density.