JPH024258Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is often used as a safety brake as an emergency measure in the event of a power outage for elevators, crane hoisting machines, etc., and uses the attractive force of a permanent magnet to apply braking to the braked object and release the brake. is performed by excitation using an electromagnetic coil. This invention relates to a so-called non-excitation actuated electromagnetic brake, and is intended to provide this type of brake that allows easy setting of excitation current for brake release and has stable brake release characteristics.

First, a conventional electromagnetic brake of this type will be explained with reference to FIGS. 1 and 2. In FIG. 1, 1 and 2 are annular yokes with a substantially L-shaped cross section, and are arranged concentrically with their disc-shaped parts facing each other in the axial direction. The permanent magnet 4 is inserted between the two disc-shaped parts. The part of the permanent magnet 4 that is adhered to the disc-shaped portion of the yoke serves as a magnetic pole.

Note that the disc-shaped part of the inner yoke is the excitation coil 3.
At the same time, it serves as a main magnetic path for the magnetic flux generated by the permanent magnet 4, and a bypass magnetic path 5 for the magnetic flux generated by the permanent magnet 4, and the outer periphery of this portion has a gap between it and the inner peripheral surface of the outer yoke 1. They are separated from each other. Reference numeral 6 denotes a friction plate provided between the opposing surfaces at the open ends, which are the magnetic pole parts of both yokes 1 and 2, and 7 an armature that opposes the magnetic pole surfaces of both yokes 1 and 2 and the outer surface of the friction plate 6. It is meshed with the hub 8 by a spline so that it can slide on the hub in the axial direction. 9 is a leaf spring for releasing the armature 7, one end of which is fixed to the armature 7, and the other end of which is fixed to the hub 8.
It is fixed in a recess provided on the outer periphery using a retaining ring 10. 11 is a braked shaft connected to the hub 8; 12 is a connecting arm attached to one end of the yoke 1; the yokes 1, 2, the coil 3, and the permanent magnet 4;
It is used to fix the magnet part consisting of the electromagnetic brake in a proper place on the machine (not shown) etc. in which the electromagnetic brake is used so that it does not rotate.

In the above configuration, when no current is supplied to the excitation coil 3, the magnetic flux Ф ₁ due to the permanent magnet 4
flows in the path shown by the dotted line, and the armature is attracted toward the magnetic poles generated on the end faces of the yokes 1 and 2 by the electromagnetic attractive force F ₀ (in FIG. 2) based on this magnetic flux, and is pressed against the friction plate 6. , a brake is applied to the braked shaft 11 via the hub 8.

Further, a current is supplied to the excitation coil 3, and the direction of the current is determined so that the magnetic flux Τ ₂ generated by this current is in the direction that cancels the magnetic flux Τ ₁ due to the permanent magnet 4, as shown by the solid line in FIG. By gradually increasing the magnitude of this current, armature 7
The electromagnetic attractive force on the spring 9 decreases as shown by curve a in FIG.
When the reaction force f _k becomes smaller, the armature is released from the magnetic pole by the force of this spring, and the braked shaft 1
The brake for 1 is released.

Furthermore, as the current in the excitation coil 3 is further increased, the magnetic flux Ф ₂ due to this current increases, and the attractive force to the armature 7 increases as shown by curve b in FIG. 2, and in this process, the excitation coil When the attractive force based on the magnetic flux Τ ₂ caused by 3 becomes larger than the reaction force f _k of the spring 9, the armature 7 is attracted again and the brake is applied to the braked shaft 11.

Such an action takes place, and in the above process of increasing the excitation current by the excitation coil 3, the range between when the armature 7 is released and when it is attracted again is called the release range, and the middle of this release range is called the release range. The excitation current value I _s corresponding to the point becomes the release setting current, and this type of electromagnetic brake normally brakes by supplying the release setting current value I _s to the excitation coil or cutting off this current. is released or the brake is applied.

However, this release setting current I _s changes due to variations in permanent magnet characteristics, ambient temperature, coil temperature rise, seasonal temperature changes, power supply voltage fluctuations, etc.
In order to always expect stable braking characteristics, it is necessary to widen the above-mentioned release range, and even if only this release range is expanded, if the value of the release setting current I _s changes, for example, the application to the excitation coil 3 will change. In an electromagnetic brake used under a constant voltage, if the above conditions change, appropriate braking operation will not be performed.

Therefore, this type of electromagnetic brake is required to expand the release range and at the same time not to change the release setting current value.

The present invention satisfies both of these requirements, and the present invention will be specifically explained below with reference to FIGS. 3 to 6. In FIG. 3, reference numeral 13 denotes a slit according to the present invention, which is placed in the center of the bypass magnetic path 5, which is also a disk-shaped portion of the inner yoke 2, over the entire circumference in parallel with the direction of the magnetic flux generated by the excitation coil 3 passing through this portion. The bypass magnetic path is divided into two paths, one for the magnetic flux on the coil side and the other for the magnetic flux on the permanent magnet side, both with the same magnetic resistance. Naokaru Slit 1
3 may be a magnetic slit, and does not necessarily have to be an air gap. As shown in another embodiment shown in FIG. It may be divided into slits 1 and 1.
If the length of 3 is set over the range in which the magnetic flux Ф ₂ generated by the excitation coil 3 flows as shown in Fig. 3, the effect described later will be performed and the purpose of the present invention will be achieved, but as shown in Fig. 4. Core 1 for permanent magnet 4 as
It is advantageous to form the slits by dividing the parts including the 4 parts from the viewpoint of ease of manufacture. Furthermore, as shown in Fig. 5, the two parts may be simply joined together with an adhesive without intervening an insulator as shown in Fig. 4, and in this case, the microscopic voids on the joint surface This becomes a magnetic slit, and the bypass magnetic path is magnetically separated into left and right sides. In FIG. 3, the configuration of other parts is the same as that of the conventional device shown in FIG. 1, so the same parts will be given the same reference numerals and their explanation will be omitted.

The embodiment of the present invention is constructed as described above, and considering the process of increasing the excitation current, at the stage when the magnetic flux due to the excitation coil is relatively small compared to the magnetic flux due to the permanent magnet when the armature 7 is released, the slit 13 is Because of this existence, the flow of magnetic flux caused by the excitation coil 3 flowing through this bypass magnetic path 5 is not obstructed by the magnetic flux that becomes the permanent magnet 4, so the magnetic flux caused by the excitation coil in that part flows easily, and as a result, the slit The armature is released with a smaller excitation current compared to the case without the armature, and when the armature is attracted again due to an increase in the excitation current after the armature is released, in other words, compared to the magnetic flux by the permanent magnet, the excitation coil When the magnetic flux is relatively large, slit 1
3, the magnetic flux from the excitation coil cannot flow through the bypass magnetic path area on the permanent magnet side, and the magnetic flux path is narrowed, causing the armature to fail unless a larger current is passed than in the case without the slit. It will not be attracted. Therefore, the release range of the armature has expanded to both sides around the release setting current value.

Figure 6 shows an actual measurement example showing the operation characteristics of the armature's suction and release when there is no slit 13 and when there is a slit 13. Curves a and a' shown by solid lines are the characteristic curves when there is no slit, and broken line b , b' are characteristic curves when a slit is provided and the slit width is set to 0.5 mm. In the figure, the attraction force on the vertical axis shows the change in attraction force when a slit is added, assuming that there is no slit 13 and the attraction force when the armature is attracted by a permanent magnet in a non-excited state is 1.0. .

As is clear from this experimental example, according to the present invention, the width of the excitation current for releasing the armature, and therefore the release range, becomes wider, so as mentioned above, changes in various conditions in the usage environment such as changes in ambient temperature etc. Alternatively, it is possible to always perform brake operation reliably under a constant excitation current regardless of manufacturing errors, and to provide a brake with stable operating characteristics. Brakes used under conditions where the release current value of the armature cannot be set by adjusting the voltage applied to the excitation coil because the range is expanded, i.e. brakes used under constant power supply voltage. Even when applied to the above, stable brake release characteristics can always be expected regardless of changes in the above conditions.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of the upper half of a conventional electromagnetic brake, Figure 2 is a diagram showing the general excitation current versus attraction force characteristics of a conventional electromagnetic brake, and Figure 3 is an example of the present invention. A longitudinal sectional view of the upper half of the electromagnetic brake, FIGS. 4 and 5 are partial sectional views showing other embodiments of the present invention, and FIG. 6 is an excitation diagram for comparing the conventional one and the proposed one. FIG. 2 is a diagram showing current versus attractive force characteristics. 3... Excitation coil, 14... Permanent magnet, 5...
Bypass magnetic path, 13...magnetic slit.

Claims (1)

[Claims for Utility Model Registration] 1. Provides a bypass magnetic path that serves as the main magnetic path for the magnetic flux generated by the excitation coil and at the same time allows a portion of the magnetic flux generated by the permanent magnet to flow, and excite braking based on the attractive force of the permanent magnet. An electromagnetic brake that is released by excitation of a coil, and in the bypass magnetic path,
A non-excitation operated electromagnetic brake characterized in that a magnetic slit is provided to divide this magnetic path into two paths, one for the magnetic flux caused by the excitation coil and the other for the magnetic flux caused by the permanent magnet, both with substantially the same magnetic resistance. 2. The invention according to claim 1, wherein the magnetic slit is formed in a deep groove shape over the entire circumference in the center of the bypass magnetic path, which is a disc-shaped portion of the inner yoke. Excitation actuated electromagnetic brake. 3 The magnetic slits are located at the center of the bypass magnetic path, which is a disc-shaped portion of the inner yoke, and are located on the left and right sides.
The non-excitation operated electromagnetic brake as claimed in claim 1, which is characterized in that the electromagnetic brake is formed by separating the two parts and joining them together.