JPH0113373Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an electromagnetic device, more specifically, an armature is attracted and held on the attraction surface of a yoke by the magnetic force of a permanent magnet, and the armature is held on the attraction surface by energizing an excitation coil. The present invention relates to a so-called release type electromagnetic device in which the armature's attraction force is canceled and the armature moves away from the attraction surface.

Generally, a release type electromagnet device is constructed as shown in FIG. That is, a pair of yokes 1 and 2
A permanent magnet 3 is sandwiched between the yokes 1 and 2 near their rear ends, and a bypass member 4 made of a ferromagnetic material such as an iron plate is in contact with the rear end surfaces of the yokes 1 and 2 and the permanent magnet 3. A coil 5 is fitted in one yoke 1 so as to be excited so as to cancel out the magnetic flux generated by the permanent magnet 3 when energized. The tip surfaces 1a and 2a of the pair of yokes 1 and 2 serve as suction surfaces for suctioning the armature 6,
The suction surfaces 1a and 2a are machined with high surface precision in order to obtain high suction force.

On the other hand, an armature 6 is disposed at a position facing the suction surfaces 1a and 2a of the yokes 1 and 2, and the armature 6 is fixed to one end of the armature support lever 7 by caulking or the like. It is rotatably disposed on the armature support shaft 8 by fitting the support hole 6a of the armature 6 into the armature support shaft 8. A circumferential groove 8a is formed in the upper part of the armature support shaft 8.
By fitting the E-ring into the armature 6, the armature 6 is prevented from falling off. Further, stopper portions 7a and 7b for regulating the rotational position of the armature 6 are formed near the support shaft 8 of the armature support lever 7. At the center of rotation of the armature support lever 7, a cylindrical bearing portion 1 is formed to be relatively long in a direction perpendicular to the surface of the armature support lever 7 in order to prevent tilting and backlash.
A fixed shaft (not shown) is fitted into the bearing portion 10, so that the armature support lever 7 is rotatable about the fixed shaft. Furthermore, a spring 11 is stretched between the armature support lever 7 and an immovable member, and the biasing force of the spring 11 gives it the ability to rotate clockwise. In the electromagnet device constructed in this way, the armature support lever 7 is rotated counterclockwise by a reset member (not shown) against the rotational behavior of the spring 11, so that the armature 6 is rotated so that the yoke 1, 2 suction surface 1
When it comes into contact with a, 2a, the armature 6 is attracted to the attraction surfaces 1a, 2a by the magnetic force of the permanent magnet 3,
Since the suction force is larger than the biasing force of the spring 11, the suction state will be maintained for a lifetime. In this attracted state, when the excitation coil 5 is energized, the armature 6 is caused by the magnetic flux generated by the energization of the coil 5.
The magnetic flux in the yokes 1 and 2 for attracting the yokes 1 and 2 decreases, and as a result, the armature support lever 7 rotates clockwise due to the biasing force of the spring 11, and the armature 6 moves onto the attracting surfaces of the yokes 1 and 2. 1a, 2a
be further apart.

In the release type electromagnet device described above, the change in the magnetic flux passing through the yokes 1 and 2 between when the coil 5 is not energized and when it is energized is explained using FIGS. 2A and B. The magnetic flux passing through the magnet 3 and yokes 1 and 2 is divided into two parts, and a magnetic circuit 12 is formed by the magnetic flux passing through the N pole of permanent magnet 3 > yoke 1 → armature 6 → yoke 2 → S pole of permanent magnet 3. , N of permanent magnet 3
A magnetic circuit 13 is formed by magnetic flux passing through the S pole of the pole → yoke 1 → bypass member 4 → yoke 2 → permanent magnet 3. The yokes 1 and 2 and the armature 6 are made of a high magnetic permeability material such as permalloy, and the bypass member 4 is made of a ferromagnetic material such as an iron plate that has higher magnetic resistance than the material of the yokes 1 and 2 and the armature 6. Therefore, before the coil 5 is energized, the magnetic resistance of the magnetic circuit 12 is lower than that of the magnetic circuit 13, and therefore, the magnetic flux emitted from the permanent magnet 3 is as shown by the solid line and broken line in FIG. 2A. ,
The magnetic circuit 12 passes through the magnetic circuit 13 more than the magnetic circuit 13, and therefore the armature 6 is attracted and held by the attraction surfaces 1a and 2a of the yokes 1 and 2 with a high attraction force. When the coil 5 is energized, a magnetic flux in the opposite direction to the magnetic flux generated by the permanent magnet 3 is generated in the coil 5, so that the magnetic resistance of the magnetic circuit 12 is greater than that of the magnetic circuit 13 at this time. Therefore, as shown in FIG. 2B, the magnetic flux of the magnetic circuit 12 passing through the armature 6 decreases, and the magnetic flux of the magnetic circuit 13 passing through the bypass member 4 increases. The adsorption force of the armature 6 decreases, and the adsorption state of the armature 6 is released.

In particular, in a release-type electromagnet device for a camera, the armature 6 is held with a high attraction force, and when the coil 5 is energized, the above-mentioned attraction force is greatly reduced with as little power consumption as possible, and at the same time, the electromagnet device is Miniaturizing the entire device is important for achieving high reliability. coil 5
The bypass member 4 plays a large role in greatly reducing the adsorption force when energized.
Formula for magnetic flux in electromagnetism, Φ＝μo×μe×F×
From A/(Φ: magnetic flux, μe: relative magnetic permeability, μo: magnetic permeability in vacuum, F: magnetomotive force, A: cross-sectional area, ; length of magnetic circuit), the magnetic flux generated in the coil 5 is bypassed. It is clear that it is proportional to the magnetic permeability of the magnetic circuit 13 containing the member 4. That is, in order to greatly reduce the attraction force of the yoke when the coil 5 is energized, it is sufficient to reduce the magnetic resistance of the magnetic circuit 13 (hereinafter referred to as the side magnetic path), but on the other hand, if you try to obtain a high attraction force, As shown in FIG. 2A, since sufficient magnetic flux must flow through the magnetic circuit 12 passing through the armature 6, the magnetic resistance cannot be reduced inadvertently. Moreover, when the coil 5 is energized, the magnetic flux passing through the bypass member 4 increases as described above, so that the side magnetic path must have enough margin to prevent magnetic saturation with this increased magnetic flux.

For the above reasons, in order to obtain a high attraction force and to greatly reduce the attraction force when the coil 5 is energized, a strong permanent magnet must be used and the bypass member 4 must be made large, but the volume occupied by the bypass member 4 is Since this cannot be ignored due to the space inside the camera, it is desirable that the bypass member 4 for forming this side magnetic path is as small as possible. Therefore, conventionally, as shown in Figs. 3 and 4, bypass members 14a, 14b, 14c made of a ferromagnetic material such as an iron plate with a thickness of about 1 mm to 0.4 mm, which is easy to press, are made of a material that does not become magnetically saturated. A permanent magnet 3 and a yoke 1 sandwiching the magnet are stacked as many as necessary to obtain the cross-sectional area.
It was bonded so that a side magnetic path was formed when it was brought into contact with the upper or lower surface of 2. but,
In this way, the bypass members 14a, 14b, 14c
For example, as shown in an enlarged view in FIG. 5, air gaps 15a and 15b are formed due to deviations in the dimensional accuracy and adhesion of the yokes 1 and 2 and the permanent magnet 3, and the bypass member is The close contact between 14a and 14b becomes incomplete, and the magnetic resistance as a side magnetic path not only increases extremely, but also
The disadvantage is that the variation becomes large.
Further, the relative magnetic permeability of the bypass member 14b is reduced by the magnetic resistance created by the air gap 15b, and when a slight air gap 15c exists between the bypass members 14b and 14c, the relative magnetic permeability of the bypass member 14c is further reduced. This will reduce magnetic permeability. In this way, if the bypass member 14c no longer plays a role as a side magnetic path, it becomes completely meaningless to further provide the bypass member 14d.

In view of the above circumstances, the purpose of the present invention is to fit a frame-shaped bypass member into the part of the yoke that holds the permanent magnet, so that it can be driven with low power and can obtain a large attraction force with a small size. It is an object of the present invention to provide an electromagnet device that can increase productivity and reduce costs.

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 6 is an assembled perspective view of an electromagnet device showing an embodiment of the present invention. This electromagnet device has a box-shaped frame body bypass member integrally formed with a ferromagnetic material in place of the conventional bypass member 4 at the rear end portion 20 of the yokes 1 and 2 that sandwich the permanent magnet 3. 21 is attached. The other structures, such as the armature support lever that rotatably supports the armature 6, are the same as those shown in FIG. 1, and are therefore not shown. That is, the bypass member 21 is a box-shaped frame body formed in the shape of a rectangular parallelepiped.
has a rectangular parallelepiped-shaped space 22 inside,
The front opening 22a is larger than the rear end surface 20a of the yokes 1, 2 that sandwich the permanent magnet 3 so that the rear end 20 of the yokes 1, 2 can be inserted into the space 22 relatively easily. It is slightly wider.

On the other hand, in the rear end portions 20 of the yokes 1 and 2 to which the bypass member 21 is attached, the yokes 1 and 2 and the permanent magnet 3 are fixed with an adhesive. ，
The lower surfaces 20b of the yokes 1, 2 and the permanent magnets 3 are fixed by pressing them against a reference surface with high surface accuracy, or by polishing the lower surfaces 20b after the fixing. 20
b is finished to a flat surface with high precision.

After this, the rear end portions 20 of the yokes 1 and 2 are
As shown in FIG. 7, the bypass member 21 is fitted and inserted into the space through the opening 22a until the rear end surface 20a abuts the inner rear end surface 21a of the bypass member 21, and in the same state, the rear end surface 20a abuts the inner rear end surface 21a of the bypass member 21. The end portion 20 and the bypass member 21 are fixed with adhesive or the like. Therefore, since the yokes 1, 2 and the permanent magnet 3 have high flatness at least on their lower surfaces, they come into close contact with the inner lower surface 21b of the bypass member 21 with an extremely small air gap or adhesive layer interposed therebetween. Further, the rear end surface 20 of the yokes 1 and 2
If a is also polished with high precision, this rear end surface 20a will also have the internal rear end surface 21a of the bypass member 21.
It will be closely followed. In this way, when the rear end portions 20 of the yokes 1 and 2 are closely integrated with the bypass member 21, the entire portion of the bypass member 21 that is in close contact with the rear end portion 20 serves as a side magnetic path. will play the role of Therefore, this box-shaped frame bypass member 21 is attached to surround the permanent magnet 3 and the rear end portions 20 of the yokes 1 and 2, so that it has better adhesion than a conventional plate-shaped bypass member. It is high and uniform, and is not easily affected by variations in component accuracy, etc., and the side magnetic path can be formed efficiently in a small size.

FIG. 8 is an assembled perspective view showing another embodiment of this invention. In other words, the bypass member 23 is made of a ferromagnetic material formed into a box shape by drawing or the like.
has a rectangular parallelepiped-shaped space 24 inside, and an opening 24a formed in the front surface. Then, the yoke 2 is inserted into the space 24 from this opening 24a.
5 and 26 and the permanent magnet 27 are each inserted individually, with the permanent magnet 27 sandwiched between the yokes 25 and 26. Thereafter, as shown by arrows in the assembled perspective view and cross-sectional view of FIGS. 9A and 9B,
Opening 24a for box-shaped bypass member 23
By mechanically applying a high compressive force from the direction of the other five surfaces other than the surface having , the box-shaped bypass member 23 is
It is caulked and fixed according to the surface shape of 7.

The yokes 25, 26 and the permanent magnet 27 fixed in this manner are in substantially complete contact with the bypass member 23 on each compression surface.
Therefore, compared to the conventional plate-shaped bypass member, the adhesion is higher and more uniform, and a smaller and more efficient side magnetic path is formed. Furthermore, in the case of this embodiment, the gluing, welding, etc. of the yoke, permanent magnet, and bypass member, which were required in the previous embodiment, can be omitted, and the precision of the parts of the yoke, permanent magnet, and bypass member can be increased accordingly. never need it. Further, it is also possible to automatically assemble the device mechanically, which previously required manual assembly, and it is possible to reduce variations in the device and reduce costs.

In the case of the above two embodiments, as shown in FIG. 10A, a box-shaped bypass member having an opening 28a on one side and a rear end surface 28b on the other side is used as the frame-shaped bypass member. As shown in Figure 10B
As shown in FIG. 2, it is of course possible to use a cylindrical shape having a rectangular parallelepiped-shaped through hole 29 with both ends open.

As described above, according to the present invention, by fitting the frame-shaped bypass member into the part of the yoke that holds the permanent magnet, the bypass member and
It is possible to provide an electromagnet device in which the adhesion between the yoke and the permanent magnet is improved, the bypass efficiency is improved, and a large attraction force is obtained with a small size, and productivity can be increased and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an assembled perspective view showing an example of a conventional electromagnet device, and FIGS. 2A and 2B are plan views respectively illustrating the non-energized state and the energized state of the excitation coil of the electromagnet device shown in FIG. 1. Figure 3 is the above-mentioned figure 1.
4 is a rear view of the electromagnet device shown in FIG. 3 taken along the - line, and FIG. 5 is an enlarged view of FIG. 4 above. 6 is an assembled perspective view of an electromagnet device showing an embodiment of the present invention, and FIG. 7 is a cross-sectional view of the main part of the electromagnet device shown in FIG. 6 above. Figure, 8th
Figure 9 is an assembled perspective view showing another embodiment of the present invention.
Figure A is a perspective view of the assembly example of the embodiment shown in Figure 8 after assembly, Figure 9B is a sectional view of the portion surrounded by the bypass member in Figure 9A, and Figures 10A and B are views of the present invention. FIG. 3 is a cross-sectional view for explaining the shape of a bypass member. 1, 2, 25, 26... York, 3, 27...
Permanent magnet, 4, 21, 23... Bypass member, 5
... Excitation coil, 6... Armature.

Claims (1)

[Claims for Utility Model Registration] A permanent magnet, a first yoke whose rear end is connected to one pole of the permanent magnet, and a second yoke whose rear end is connected to the other pole of the permanent magnet. an armature that is attracted to the front end surfaces of the first and second yokes by the magnetic force of the permanent magnet; and an armature that is wound around at least one of the first and second yokes and is energized. By reducing the attraction force due to the magnetic force of the permanent magnet, the first and second
and an excitation coil that separates the armature from the distal end surface of the yoke, the electromagnetic device comprising: an excitation coil that separates the armature from the distal end surface of the yoke; An electromagnet device characterized in that a bypass member made of a ferromagnetic material molded into a frame shape is fitted onto the outside by caulking.