JPS5947442B2 - electromagnet device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electromagnetic device having a permanent magnet core.

There are two types of electromagnetic devices that perform certain operations by attracting the armature by energizing a coil, and another type in which the armature is attracted to a permanent magnet core in advance and the magnetic force of the permanent magnet of the core is struck by the coil current. Some types perform certain operations by releasing the armature by extinguishing it.

The latter type requires only a coil current to flow at the moment of operation and consumes little current, so it is often used in camera shutter mechanisms and the like that are operated by small-capacity batteries.
The present invention is directed to this type of electromagnetic device. FIG. 6 shows a known example of the electromagnet device described above, in which 21 and 22 are yokes, and 28 is a permanent magnet.

The yokes 21 and 22 are separate bodies, and are fixed with a permanent magnet 28 in between, forming a U-shaped permanent magnet as a whole.
21a and 28a are magnetic pole end faces. 24 is a coil wound around one yoke, and 25 is a movable iron piece.

The iron piece 25 is pulled in the direction of being pulled away from the magnetic poles 21a and 28a by a spring 26, and is pulled away from the magnetic pole faces 21a and 28a by appropriate means.
When brought into contact with the magnetic pole 28a, it overcomes the force of the spring 26 and remains attracted to the magnetic pole surface. Now, when a current is passed through the coil 24 in a direction that weakens the magnetization of the yokes 21 and 22, the iron piece 2
5 is separated from the magnetic pole surface by the action of the spring 26. In such a structure, the magnetic pole end faces 21a and 28a are separate yokes 21 and 2.
2, the parallelism of the contact surfaces of the permanent magnet 28 and the yokes 21 and 22 must be properly machined in order to align them on one plane, otherwise the inclinations of both sides of the yokes 21a and 28a will be unequal. Further, during assembly, it is necessary to connect the yokes 21, 22 and the permanent magnet 28 so that both surfaces of the yokes 21a, 28a are aligned in a line. In this way, in conventionally known electromagnet devices, the magnetic core has a composite structure of a permanent magnet part and a magnetically soft ferromagnetic part, which is cumbersome to work and assemble. It is important for the armature to be machined so that there are no gaps in the contact state in order to increase the armature holding force, but it is difficult to finish the contact surface to be flat. The main object of the present invention is to provide an electromagnet device that solves the above-mentioned problems.

The present invention has a configuration including an armature that is urged in a direction to be pulled apart by an external force, and a magnetic circuit in which a permanent magnet is partially inserted and a coil is wound around a magnetic core that constitutes the magnetic circuit. A high-magnetic-resistance portion is provided, and one pole face of a permanent magnet is brought into contact with the high-resistance part, and a high conductivity is created between the other pole face of the permanent magnet and the magnetic core by straddling the high-resistance part. The present invention provides an electromagnet device including a permanent magnet holding member made of a magnetic material. The present invention will be explained below with reference to Examples. In Fig. 1, 1 is a U-shaped yoke made of a high magnetic permeability material, 1 is a coil, and 8 is an armature, which is biased by a spring 9 in the direction of being separated from the yoke 1. It is something that

A through hole a is bored in the yoke 1, and portions 3 and 4 with narrow cross-sectional areas of the yoke are formed on both sides of the hole a. A rare earth metal permanent magnet 5 is placed near the through hole 2 and fixed by a holding plate 6 provided so as to straddle the through hole 2. The holding plate 6 is also made of a high magnetic permeability material and is fixed to the yoke 1 by spot welding or the like. With such a configuration, the magnetic flux generated by the permanent magnet 5 becomes as shown in FIG. This circuit has an air gap 2 and narrow sections 3 and 4, and the sections 3 and 4 are magnetically saturated, so the magnetic resistance of this circuit is high, and most of the magnetic flux from the magnet 5 is flows in a circuit passing through the yoke 1 and the armature 8 and holds the armature 8 in the yoke section against the force of the spring 9. In this state, coil 1
When a current is instantaneously passed in a direction to eliminate the magnetic flux generated by the permanent magnet 5, the armature 8 is separated from the magnetic pole face of the yoke by the action of the spring 9, and a certain operation is performed by this movement of the armature. A movable piece 10 made of a high magnetic permeability material is provided outside the portion of the yoke 1 in which the through hole 2 is bored, and can be moved toward and away from the yoke 1 by a mechanism not shown.

Usually, this movable piece is separated from the yoke 1 and has almost no magnetic effect. Now, when the moving piece 10 is brought into contact with the yoke 1 in the down position where the armature 8 is attracted to the magnetic pole surface of the yoke 1, a part of the magnetic flux created by the permanent magnet 5 will pass through the moving piece 10. become. That is, the movable piece 10 is a permanent magnet 5
On the other hand, a magnetic circuit that does not pass through the armature is formed in parallel with the magnetic circuit that passes through the yoke and armature.
If the magnetic resistance of this newly created magnetic circuit is equal to the resistance of the magnetic circuit passing through the armature, the magnetic flux passing through the armature will be halved. The force with which the yoke 1 attracts the armature 8 is proportional to the square of the magnetic flux passing through the magnetic pole surface, so when the magnetic flux is halved, the attraction force drops to 1/4. Therefore, if the tensile force of the spring 9 is set to approximately half the maximum force with which the yoke 1 is adsorbing the armature, the armature can be detached from the yoke by bringing the movable piece 10 into contact with the yoke 1. can be done. The structure for attaching the permanent magnet 5 to the yoke 1 may be as shown in FIG. 3, for example, in addition to the structure shown in FIGS. 1 and 2.

That is, the holding plate 6 is a straight plate, and has a structure in which a base metal 6c made of a high magnetic permeability material and having the same thickness as the permanent magnet 5 is placed on the opposite side of the permanent magnet 5, and is bridged by the holding plate 6. Furthermore, instead of drilling the through hole 2, a cut 2 may be made in the yoke 1 to create a portion with a small cross-sectional area as shown in Fig. 4a, and a portion with a small cross-sectional area may be made as shown in Fig. 4b.
A small cross-sectional area of the yoke (near which a permanent magnet is attached) may be provided on one arm of the yoke, as shown in FIG.

It is easier to make a cut on the machined surface, and from the viewpoint of the mechanical strength of the magnetic core, it is better to make a through hole. Furthermore, the fourth
A configuration as shown in FIG. c is also possible. In the configuration shown in FIG. 4c, permanent magnets 5, 5 are arranged before and after a portion of the yoke 1 with high magnetic resistance. Here, "front and rear" means a direction along the direction of flow of magnetic flux in the yoke 1. These two permanent magnets 5, 5 are attached to the back surface of the yoke 1 by pressing a high magnetic permeability holding member 6 which is brought into contact with both permanent magnets so as to connect both permanent magnets 5, 5 across the high magnetic resistance portion. The washer 13 made of a non-magnetic material which is brought into contact with the yoke 1 (-) is fixed by being tightened to the yoke 1 by a screw 14 made of a non-magnetic material passed through the high magnetic resistance part 2. When the magnetic poles of the permanent magnets 5, 5 are in the relationship as shown in the figure, the magnetic flux is from the left side of the yoke 1 in the figure to the left permanent magnet 5,
Needless to say, it flows to the right side of the yoke 1 through the high magnetic permeability holding member 6 and the right permanent magnet 5. In this way, by connecting the yoke at the narrow cross-sectional area instead of dividing it into two parts, the entire yoke can be treated as a single component, making it easier to finish so that both magnetic pole end faces are accurately positioned on the same plane. , the armature is better held. Moreover, as shown in FIG. 5 above,
In other words, even if a movable piece is provided on the tail end side of the yoke 1, for the same reason, the contact with the yoke is good and the function of forming a magnetic flux bypass for the armature is stable (without variations from product to product). )can get. FIG. 5 shows an example in which the electromagnetic device described above is used to operate the shutter of a camera.

In the figure, 11 is a photometry circuit, 12 is a timer and switching circuit for setting the exposure time, and Mg is the above-mentioned electromagnetic device, and when the armature moves away from the yoke, the shutter closing member is activated. Switch S is usually on the contact a side, in this case transistor Q
is in a cut-off state, and capacitor C is being charged by power supply E. When the shutter button is pressed, the switch S is switched to the contact b side, and the photometry circuit and timer switching circuit start operating. When a predetermined period of time has elapsed after the shutter is opened, the transistor Q is made conductive by the timer switching circuit 12, and the charge in the capacitor C is instantly discharged through the electromagnetic device Mg, and the armature is separated from the Mg yoke and the shutter closes. start. If the movable piece 10 is provided as shown in FIG. 5, it is possible to separate the armature 8 and close the shutter without consuming power. That is, when the movable piece 10 is brought into contact with the yoke 1, the force with which the yoke 1 attracts the armature 8 is reduced to 1/4 as described above.
The armature 8 automatically separates from the yoke 1 because the tensile force of the spring 9 overcomes this attraction force. Therefore, by using this movable piece 10, mechanical shutter control as described below is also possible. For example, in order to enable so-called bulb photography in which the shutter is kept open while the shutter button is pressed, the movable piece 10 is moved to the yoke 1 in conjunction with the movement of the shutter button to return from the pressed position. What is necessary is to provide an interlocking mechanism that brings it into contact with.

In this case, a switching member is provided on the camera body that can be set to a position for bulb photography and a position for normal photography, and when this switching member is set to the position for normal photography, In this case, only when the interlocking mechanism between the shutter button and the movable piece is broken and the switching member is set to the bulb exposure position, the interlocking mechanism moves the shutter button and the movable piece as described above. Configure them so that they work together. Since the timer switching circuit is normally turned off when the valve is operating, conventional cameras using this type of degaussing electromagnet require some kind of mechanical shutter closure mechanism in addition to the electrical shutter closing mechanism that includes the electromagnet. The valve could not operate without a single-closing mechanism, but if a movable piece like the one shown in the above embodiment is provided, the valve can be easily operated by doubling most of the electrical shutter-closing mechanism. The shooting function can be achieved. Furthermore, by adding a mechanism that can arbitrarily change the timing from when the shutter button is pressed until the movable piece 10 comes into contact with the yoke 1, an electric shutter that can also be mechanically controlled. The camera can be implemented with an extremely simple configuration.

According to the electromagnet device of the present invention, the magnetic core portion of the magnetic circuit is divided into two
Since it is configured so that it is not divided into parts but connected at a narrow cross-sectional area, the magnetic core part can be handled as a single component when processing the magnetic pole end face, for example, when polishing the magnetic pole end face.

Therefore, according to the present invention, there is no fear that the portions on which the pole end faces are formed will be misaligned during processing, and both pole end faces can be formed so that they are precisely located on one plane. This makes it possible to increase armature retention as much as possible.

[Brief explanation of drawings]

FIG. 1 is a partially exploded perspective view of one embodiment of the present invention, FIG. 2 is a rear view of the above, FIG. 3 is a rear view of another embodiment, and FIG. 4 is a plan view of another embodiment. FIG. 5 shows a shutter control circuit of a camera to which the electromagnet device of the present invention is applied, and FIG. 6 shows a conventional example, with FIG. 5A being a front view and FIG. 6B being a side view. 1...Yoke (magnetic core), 5...Permanent magnet, 6...
- Permanent magnet holding member, 1... Coil, 8... Armature, 9... Spring that separates the armature from the yoke, 10... Movable piece made of high magnetic permeability material.

Claims (1)

[Claims] 1. An armature that is biased in the direction of being pulled apart;
It has a structure in which a magnetic circuit is formed with a magnetic core to which a permanent magnet is attached and a coil is wound, and the magnetic core has a part with a large magnetic resistance by providing a through hole or notch in a part of the magnetic core. The permanent magnet is brought into contact with the part with high magnetic resistance, and the permanent magnet with high magnetic permeability is placed between the permanent magnet and the magnetic core so as to straddle the part with high magnetic resistance. An electromagnet device equipped with a permanent magnet holding member made of material. 2. The electromagnet device according to claim 1, wherein the magnetic core is a flat, substantially U-shaped member. 3. Permanent magnets are arranged one each before and after the high magnetic resistance part along the direction of magnetic flux flow, and the permanent magnet holding member is made of a high magnetic permeability material that is in contact with these permanent magnets. The electromagnet device according to claim 1 or 2, which is a flat plate. 4. A base metal made of a high magnetic permeability material having the same thickness as the permanent magnet is placed in a position facing the permanent magnet with a high magnetic resistance part in between, and the base metal and the permanent magnet are made of a high magnetic permeability material. The electromagnet device according to claim 1 or 2, wherein the electromagnet device is made of a flat permanent magnet holding member. 5. The electromagnet device according to any one of claims 1 to 4, wherein the permanent magnet holding member is fixed to the magnetic core.