JPS62243307A - Electromgnetic device - Google Patents

Abstract

PURPOSE:To obtain an electromagnetic device in which a plenty of fluxes can be induced with a little driving force and whose winding work can be performed easily and whose coil can be fitted to a core easily by a method wherein the thickness of the frame of a coil bobbin is made to be thin and a copper wire is wound in the state of fitting a magnetic unit into the frame. CONSTITUTION:A yoke 1 and a core 2 are solidly formed continuously. The rear end 7 of a needle 6 actuated by a spring 5 is pressed against the tip of a movable core 4 facing the attracting plane 3 of the core 2. A coil 8 is com posed of a coil bobbin 10 whose frame 9 has the thickness of 0.2mm and is composed of synthetic resin, a square tube-shape magnetic unit 11 which is fitted into the frame 9 and a copper wire wound on the frame 9. Flanges 13 are provided on both ends of the bobbin 10 and terminals 14 are inserted into the one of two flanges 13. The magnetic unit 11 is formed by folding one sheet of steel plate and a gap is formed at a part of its circumference to suppress the creation of eddy current. Conductive patterns 19 which have through-holes 18 into which the terminals 14 are inserted are formed on a circuit board 17 and both of the poles of the coil 8 can be connected to the circuit board 17 by dipping in a solder bath.

Description

[Detailed description of the invention] Industrial applications TECHNICAL FIELD This invention relates to electromagnetic devices.

BACKGROUND ART As shown in FIG. 5, an electromagnet 31 used, for example, in a wire dot printer head includes a yoke 32, an iron core 33, a coil 34, and a movable iron core 35.
By energizing, the movable iron core 35 is attracted to the iron core 33 and the needle 36 is driven. In such an electromagnet 31, it is difficult to form the coil 34 by winding copper wire around a plurality of cores. Although there is a method of winding the copper wire in advance using a jig and hardening it into a predetermined coil shape with an adhesive before attaching it to the iron core 33, the winding work and wiring work are still troublesome. For this reason, generally the coil bobbin 37
A coil 34 is formed by winding a copper wire around the coil 34, and then attached to the iron core 33. 38 is a circuit board.

6 and 7 show the structure of a part of the electromagnet 31,
A terminal 40 to which both ends of the copper wire 39 are connected is provided on the coil bobbin 37 on which the copper wire 39 is wound, and when the coil bobbin 37 is attached to the iron core 33, the terminal 40 is fitted into a through hole of the circuit board 38, and the terminal 40 is inserted into the through hole of the circuit board 38. The fitting part (connection part) is soldered by tapping to improve the wiring work.

Problems to be Solved by the Invention On the other hand, the coil bobbin 37 is made of synthetic resin because it requires insulation, and in order to obtain a large amount of magnetic flux with a small drive power, it is necessary to increase the magnetic path cross-sectional area and increase the wall thickness of the coil bobbin 37. It needs to be made smaller. However, if the wall thickness of the coil bobbin 37 is reduced, the coil bobbin 37 will be deformed by the tightening force of the copper wire 39 during winding, making it difficult to fit into the iron core 33.

Further, losses in the magnetic circuit include losses due to resistance of the copper wire 39, hysteresis loss of the yoke 32, eddy current loss, and the like. Of these, as shown in FIG. 7, when the amount of magnetic flux changes, the eddy current flows in the direction of the arrow that cancels out the change in the amount of magnetic flux, worsens the rise and fall characteristics of the magnetic flux B, and causes the yoke 32 to deteriorate. cause fever. This poses a problem in the wire dot printer head, which hinders high-speed operation and miniaturization of the device.

As shown in FIG. 8, there is a method for reducing eddy currents by stacking a plurality of iron plates to form a yoke 32 and an iron core 33, but this is difficult to manufacture. In particular, as shown in FIG.
3 arranged in a ring shape and formed integrally is extremely difficult to manufacture.

The present invention has been made in view of the above points, and an object of the present invention is to provide an electromagnetic device that can obtain a large amount of magnetic flux with a small driving force, and can easily perform winding work and attach a coil to an iron core. With the goal.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 4. A yoke 1 and an iron core 2 are integrally and continuously formed. A movable iron core 4 facing the suction surface 3 of the iron core 2 is held on the end face of the yoke 1 so as to be able to rise and fall freely. This movable iron core 4
The rear end 7 of the needle 6 is biased by the spring 5.
is in contact.

A coil 8 is then provided. This coil 8 is
A coil bobbin 10 made of synthetic resin and having a wall thickness of 0.2 mm in the cylindrical portion 9, and a rectangular cylindrical magnetic body 11 fitted to the inner periphery of the cylindrical portion 9.
and a copper wire 12 wound around a cylindrical portion 9. The coil bobbin 10 has flanges 13 at both ends, and a terminal 14 is inserted into one flange 13. Magnetic material 11
is formed by bending a single iron plate, and therefore,
A gap 16 is formed in a part of the outer periphery. A conductive pattern 19 having a through hole 18 into which the terminal 14 is inserted is formed on the circuit board 17.

In such a configuration, although the wall thickness of the cylindrical portion 9 of the coil bobbin 1o is thin, by winding the copper wire 12 with the magnetic body 11 fitted into the cylindrical portion 9, the cylindrical portion 9 becomes a copper wire. Deformation due to the tightening force of the wire 12 can be prevented.

Furthermore, when the coil bobbin 10 and the magnetic body 11 are fitted into the iron core 2, the terminals 14 can be inserted into the through holes 18, and both poles of the coil 8 can be connected to the circuit by dipping the back side of the circuit board 17 in a solder bath. It can be connected to the substrate 17. Therefore, the winding work, the assembly work of the coil 8 to the iron core 2, and the wiring work can be easily performed.

Further, when the coil 8 is energized, the movable iron core 4 is attracted to the suction surface 3 of the iron core 2, and the needle 6 is driven. At this time,
Since the wall thickness of the cylindrical portion 9 of the coil bobbin 10 is thin, and the magnetic body 11 reinforcing the coil bobbin 9 increases the magnetic path cross-sectional area, a large amount of magnetic flux can be obtained with small driving power.

Furthermore, since the gap 16 is formed in a part of the outer periphery of the magnetic body 11, the generation of eddy current can be reduced.

It should be noted that the magnetic material is not limited to a cylindrical material6, but may have a U-shaped cross section, for example, as long as it forms part of the core after assembly and reinforces the coil bobbin 10 during winding. It can be anything.

Effects of the Invention Since the present invention is constructed as described above, the magnetic material prevents deformation of the coil bobbin during winding, and the winding work and the assembly work of the coil bobbin to the iron core can be easily performed. This has the effect of increasing the cross-sectional area of the magnetic path and obtaining a large amount of magnetic flux with a small drive power.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the present invention, in which Figure 1 is a vertical side view, Figure 2 is an exploded perspective view, Figure 3 is a perspective view of the coil, and Figure 4 is an assembled state. 5th perspective view showing
The figure is a longitudinal side view showing the structure of an electromagnet used in a conventional wire dot printer head, FIG. 6 is an exploded perspective view showing the conventional electromagnet, and FIG. 7 is a perspective view showing its assembled state.
FIG. 8 is a perspective view showing another conventional yoke and iron core structure. 1...Yoke, 2...Iron core, 4...Movable iron core, 10...
・Coil bobbin, 11...magnetic material

Claims (1)

[Claims] 1. An iron core and a yoke, one end of which faces the movable iron core, are magnetically coupled to each other, and are fitted to the inner periphery of the coil bobbin during winding, and fitted to the iron core after winding. An electromagnetic device characterized by being provided with a magnetic body having a cylindrical shape or a U-shaped cross section. 2. The electromagnetic device according to claim 1, wherein the cylindrical magnetic body is formed by bending an iron plate.