JPS5917214A - Coil bobbin for electromagnetic part - Google Patents

Abstract

PURPOSE:To reduce the generation of heat in a coil section, and to minimize a temperature rise by bringing the conductor of an inner-most central section of a coil, on which a wire is wound, into contact with a core in a thermal conduction manner. CONSTITUTION:A plurality of the cores 1 of a trapezoid section shape are arranged approximately circularly, the oblique sides of adjacent two cores 1 are mutually in parallel, and the larger the space is, the larger space given to the coils becomes. That is, half the space C represents the maximum value of the thickness of one coil, and a large space can be given to the coil. Thermal resistance between the coil and the core can be made extremely small because the conductor 13 of the coil most central section can be in contact directly with the core 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention The present invention relates to a coil bobbin for electromagnetic components, and is particularly suitable for coils that generate a lot of heat and have a large temperature rise, such as electromagnetic solenoids or wire dot matrix print heads. This relates to coil bobbins.

(2) Prior Art FIG. 1 shows a coil in a conventional wire dot matrix print head.

A plurality of cores 1 are arranged in a substantially circular shape. The bobbin 2 is usually made of a resin that has good heat resistance and good thermal conductivity.A coil 6 is wound around the bobbin 2, and the center of the bobbin 2 is inserted into the core 1 to generate an electromagnetic force. is formed.

In the known wire dot matrix print head, the magnetic force generated in the electromagnetic force generating section is transferred to the armature (
(not shown). When this armature is operated, a print wire (not shown) engaged with it is driven, jumps out from the tip of the lid, and performs impact printing on the printing paper. In this case, the larger the magnetic force acting on the armature, the faster the printing operation can be. It is well known that if you increase the current value flowing through coil B, the magnetic force will also increase.
Coil 30 by passing a large current through coil 3
The temperature increase due to heat generation poses a major problem to print head performance and lifespan.

Normally, the heat generated by the coil 3 is transmitted from the outer surface of the coil B to surrounding members or into the air, and is also transmitted to the core 1 through the bobbin 2, which is a core of 60 coils, and is dissipated. In this case, it is well known that the core 1, which is an iron core, has relatively good thermal conductivity and thus becomes an effective member for transmitting the heat of the coil 5 to the outside.

Next, using FIG. 2, we will further discuss the problem of problems with heat transfer from the coil 6 to the core 1 and the heat generation of the coil 3 itself. Second
Figure (a) shows Bobi/2 which is normally used for these 30-turn coil cores. The bobbin 2 includes a trapezoidal cylindrical portion 4 and flanges 5 disposed at both ends thereof to maintain the shape of the wound coil 3. A coil 6 is wound around the outer periphery of the cylindrical portion 4, and the inner wall portion of the cylindrical portion 4 is inserted into the core 1 as shown in FIG. 2(b).

For wire dot matrix print heads, core 1
As mentioned above, a plurality of cores are generally arranged in a substantially circular shape, and in order to ensure a large magnetic force generated in the core 1, the cross-sectional area of the core 1 is increased. Therefore, the interval between the plurality of cores 10 inevitably becomes narrower. In such a situation, two major problems arise regarding heat generation from the coil 60. The first problem is the resistance value of the coil 6. It is known that the resistance value of the wound coil 6 increases approximately in proportion to the number of windings and decreases approximately in proportion to the cross-sectional area of the conductor. It is also known that when the coil 3 is energized, Joule loss occurs in proportion to this resistance value and heat is generated. That is, in order to reduce heat generation, it is a good idea to use a conductor with a large cross-sectional area, that is, a large diameter, for the coil 3. However, in the arrangement of a plurality of cores 1 as described above, the spacing between the cores 1 cannot be made larger than a certain value due to overall size constraints, and therefore the diameter of the conductor of the coil to be wound also depends. As a result, the resistance value is also determined by the value. In short, the first problem is that the diameter of the conductor wire of the coil 3 is inevitably limited due to the shape and dimensions of the core 1, so there is a limit to reducing the resistance value of the coil 3, and the heat generation is reduced below a certain value. This means that it is not possible.

The second problem is the problem of heat conduction from the coil 6 to the core 1. As mentioned above, the core 1 is made of iron-based material, and the coil 6
It is used as a member that relatively effectively transmits and dissipates the heat generated by the outside. However, since the coil 3 is wound around the bobbin 2 having a cylindrical part 4 as shown in FIG. 2(a), even though the bobbin 2 is made of a material with relatively good thermal conductivity, Naturally, the thermal conductivity of the bobbin 2, which is made of resin, is lower than that of iron, copper as the coil conductor, or other metal materials. Since such a bobbin 2 is interposed between the coil 3 and the core 1, the thermal resistance from the coil 6 to the core 1 cannot be reduced. Therefore, the heat generated by the coil 60 is prevented from being effectively transmitted and dissipated to the outside by the core 1, and the temperature rise in the coil 6 becomes even larger.

As for the above two problems, it is understood that in electromagnetic components that require a specific core shape and dimensions, a coil using a conventional bobbin having a cylindrical portion has a big problem in terms of coil heat generation. In order to solve this problem, a bobbinless coil as shown in FIG. 2(C) has conventionally been used. This method is as described below.

The coil 3 has almost the same shape as the core 1, and is once wound around an arc 6 which is slightly thicker than the core 1. The arc μ used for this winding
6, the conductors 7 of the coil B are bonded to each other with an adhesive or the like, and the coil 3 maintains its wound shape even after the A μ6 is removed. Alternatively, the conductor 7 may be one in which the outer periphery of the insulating coating is further coated with a heat-welding material. A method is used in which the conductors 7 of the coil 3 are joined to each other by melting a heat-fusible material by heating the coil 6 or the like. By using such a bobbinless coil, the bobbin 2 as described above can be made unnecessary.

Therefore, the dimensions of the coil portion can be made larger with respect to the interval between the cores 10 than when the bobbin 2 is used, and the conductor diameter of the coil 3 can be made larger. Therefore, the coil resistance value can be reduced and heat generation can be reduced. or,
Since bobbin 2 does not exist between coil 3 and core 1,
The coil 3 can be brought into direct contact with the core 1, making it possible to reduce the thermal resistance of the coil 3 to the core 1 and to reduce the temperature rise value. However, this bobbinless coil also has the following problems.

The first problem is a work problem. As mentioned above, after winding the conductor of the coil 3, it is necessary to bond it.
Manufacturing costs increase. Needless to say, when a so-called self-welding wire coated with a heat-fusible material is used, the cost is higher than that of an ordinary conducting wire. Furthermore, as mentioned above, this self-welding wire has an insulating coating on the conductor.
Furthermore, because the upper layer button is coated with heat-welding material,
The overall thickness of the coating layer is large, and even if the diameter of the conductor itself is the same, the outer diameter is larger than that of a normal conductor with only an insulation coating. For this reason, even though the size of the coil winding portion is secured by eliminating the bobbin, there is a disadvantage that the size cannot be effectively allocated solely to increasing the conductor diameter, and the effect cannot be effectively utilized.

(6) Summary of the Invention An object of the present invention is to provide a coil bobbin for reducing heat generation and temperature rise in the coil portion of an electromagnetic component. In other words, by using a coil bobbin and winding the coil on it, an increase in the manufacturing cost of the coil can be prevented, and the thermal resistance between the coil and the core can be maintained, which is the same as that of the conventionally implemented ear, 1 bobbinless coil. The space given to the coil winding can be effectively reduced to the diameter of the conductor by using a conductor with only a normal insulation coating layer, which is not coated with the heat-fusible material normally used in bobbinless coils. The objective is to provide a coil using a large conductor wire diameter, to reduce the resistance value of the coil, and to reduce the heat generation of the coil. By using such a coil, it is possible to ensure the magnetic force determined by the core shape and dimensions, and to provide an electromagnetic component that generates less heat and has less temperature than conventional techniques. Particularly in recent years, wire dot matrix printheads have been required to be smaller and faster, and problems related to heat generation and temperature rise in the coil portion are increasing. The present invention is suitable for solving such technical problems.

(4) Embodiment of the invention FIG. 6 shows an embodiment of the coil bobbin of the invention. In this embodiment, the core into which the coil bobbin is inserted is a trapezoidal column.

The bobbin consists of two pillars 81 and 82 extending along two parallel sides of the trapezoid of the core, and a collar 91 provided parallel to both ends of the pillars.
．． Consists of 92. Two metal pins 10 are embedded in one collar 92, and constitute a coil terminal for power supply. The widths of the two pillars 81 and 820 are approximately equal to the widths of two parallel sides of the trapezoid of the inserted core. When winding a coil on a bobbin with this configuration,
By using the arbor 11, it is possible to prevent the two pillars from being deformed by the tightening force during winding.

FIG. 4 is a diagram showing a state in which a coil is wound around the coil bobbin of the present invention. The coil 12 is wound in a trapezoidal shape along the two bobbin supports 81 and 82 and Arno (11).
Even after the winding is finished and the AHA 11 is removed, it is held down by the buckwheat noodles 91 and 92, so that it can be handled without losing its shape. In other words, there is no need to use expensive wires such as self-welding wires for coil winding, and wires with only insulation coating can be used, and the coil space factor (conductor area per unit volume) be able to improve the ratio of The starting and ending ends of the coil 12 are joined to the pin 10 by conventional winding and soldering to complete the coil assembly.

In this example, the coil is wound on the coil bobbin (and the bobbin of the winding part has only two supports, and the other two sides have the core conductor 16 at the center when the coil is inserted). An example of this is shown below.
The diagram shows a wire dot matrix print head.
This shows an arrangement of electromagnetic components that requires a very dense arrangement of multiple cores and coils. A plurality of cores 1 having a trapezoidal cross section are arranged in a substantially circular shape. In this case, the diagonal sides of two adjacent cores 1 are parallel to each other, and the larger the distance between them, the larger the space given to the coil. That is, half of the interval C is the maximum value of the thickness of one coil1. In the prior art described with reference to FIG. The half dimension obtained by subtracting 2 times is the maximum value of the coil thickness. That is, in the case of this embodiment, it is possible to provide a larger space to the coil. These differences are summarized in Table 1 using symbols. In this case, a comparison with the case of the bobbinless coil described in the prior art will be described at the same time.

C: Core spacing N: Number of winding layers of the coil f: Coating thickness of thermal welding material on the self-welding wire feathers d: Coil conductor core wire diameter t: Wall thickness of the cylindrical part of the coil bobbin e: Thickness of the insulation coating layer of the wire )v Table 1> As shown in Table 1 above, by using the first embodiment of the present invention, it is possible to wind a coil of a conductor with a larger diameter than in the conventional method, making it possible to create a coil with a small resistance value. becomes possible.

Therefore, there is a great advantage that the amount of heat generated during use can be reduced. Table 2 shows a comparison of resistance values when this embodiment is applied to a wire dot matrix print head having 24 wires.

C=2mm t=o2mm N=4 layers e-0
, f) 12mm f = 0.0055 Core circumference 215
．． 5B1mn: Total number of coil turns = 220 (Table 2) The above has described the effect of reducing the resistance value of the coil, but the even greater characteristic effect of the embodiments of the present invention is the improvement of heat conduction. be. That is, in FIG. 4, since the conductor 13 at the top of the coil can directly contact the core 1, the thermal resistance between the coil and the core can be extremely reduced. It is similar to a conventional bobbinless coil, and the heat of the coil section can be effectively transferred to the core and dissipated through it, so the temperature rise in the coil can be kept small. In such a case,
Heat conduction can be further improved by using a method such as filling grease or resin with good thermal conductivity between the coil and the core. Even if the core is not electrically insulated, the risk of the core breaking the insulating coating of the conductor at the top of the coil and causing a short circuit can be avoided. Furthermore, in order to enhance the effect of this embodiment, the coil bobbin is preferably made of a metal material with good heat conductivity, such as copper or aluminum. In this case, it is possible to form a terminal vial as shown in FIG. 4 by insulating it and embedding it.

Next, the second and third embodiments will be described with reference to FIGS. 6-7.

FIG. 6 shows a coil bobbin according to another embodiment of the present invention. This is a thin sheet of metal, such as a copper plate,
This is an example in which a coil bobbin was made by bending an aluminum plate, a nickel silver plate, a stainless steel plate, etc. That is, two pillars 1
It consists of 41.142 and brim 151.152.153. A notch 16 is provided in a part of the collar 151 to prevent eddy current from flowing. The coil bobbin shown in FIG. 7 is also an example in which a coil bobbin is made by bending a single thin metal plate. In this case, the bobbin is inserted into a trapezoidal or rectangular core, and one bobbin wall has an opening with respect to the adjacent core. In this case, if the thickness of the bobbin is c-1, then -d = -2e, and the diameter of the conductor core wire that can be wound is slightly smaller than in the first embodiment, but the bending shape of the bobbin If emphasis is placed on the effect of simple construction and good thermal conductivity since it is made of metallic material, it will bring greater effects than conventional technology.As shown in Figures 6 and 7. For example,
When constructing a coil bobbin with a metallic material, care must be taken to ensure the insulation of the conductor at the top of the coil, but if the performance is impaired only by insulation coating on the wire, insulation coating should be applied to the bottom of the bobbin. is used as an effective means. Furthermore, in any case, when winding the coil, the first
It is better to wind the wire using an arbor (not shown) as in the embodiment described above.

Next, the fourth embodiment will be explained with reference to FIG.

The fourth embodiment is a method of dividing the bobbin into two parts. The material of the bobbin may be either resin or metal. A bobbin is composed of two supports 20 and 21 having flanges at both ends. In this case, when winding the wire,
The bobbin is mounted on the arbor 11 and wound to form the coil 12. After winding, before removing the arbor 11, remove the bobbin 20.
．． 21 and coil 12 with adhesive.

Coil assemblies can be made by joining them with etc. The operation of this example is similar to that of the first, second, and sixth embodiments described above, so a detailed explanation will be omitted.

In the embodiments described above, the cores are arranged in a substantially circular shape, but according to the gist of the present invention, the cores may be arranged in any direction; for example, as in a line printer, the cores may be arranged in one horizontal direction. The present invention also exhibits effective effects on the core.

5) Effects of the Invention As described above, according to the present invention, since the bobbin that serves as the mandrel of the coil winding inserted into the core is provided with an opening in part or between it and the adjacent core, The conductor at the top of the coil can be brought into direct contact with the core, and the heat generated by the coil can be effectively transmitted to the core, making it possible to reduce the temperature rise of the coil by 1°. However, since the coil bobbin does not have a wall around the entire circumference of its winding section, even if the distance between the cores is narrow, the space of the coil winding section will not be reduced due to the thickness of the bobbin, and therefore the wire diameter will be reduced. A thick conductor can be wound as a coil, resulting in a coil with low resistance and low heat generation. Furthermore, by constructing the coil bobbin from a metallic material, thermal conductivity is improved, and the heat dissipation effect of the coil portion is significantly improved. When the present invention is applied to a coil for an electromagnetic component that operates at high speed, especially in a wire dot type print head having a large number of wires, the present invention generates little heat and temperature rise, and is economical.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing electromagnetic components in a wire dot matrix print head. FIG. 2 is a diagram showing the arrangement and configuration of coils in the prior art. FIG. 3 is a perspective view showing a coil bobbin according to an embodiment of the present invention. FIG. 4 is a perspective view showing a coil according to an embodiment of the present invention. FIG. 5 is a sectional view showing a coil arrangement according to an embodiment of the present invention. FIGS. 6 and 7 are perspective views showing coil bobbins according to other embodiments of the present invention. FIG. 8 is a perspective view showing a coil and a coil bobbin according to an embodiment of the present invention. 1...core, 2...bobbin, 6...
Coil, 4... Cylindrical part, 5... Collar,
8... Support, 11... Arbor,
13...Centermost Ω conductor. W, All′i″161′ Tatami Go Rōsai ° 2 years old 4 years old S Figure Sai b Figure 1 3 f 8 Figure

Claims (4)

[Claims] (1) A winding core member of a coil that is wound around a core, and is composed of a wall-like member that is partially arranged along the outer circumference of the core, and the conductor at the centermost part of the wound coil is connected to the core. A coil bobbin for electromagnetic parts characterized by being configured so that it can be contacted in a thermally conductive manner. (2) The coil bobbin for electromagnetic components according to item 1, wherein an opening is provided in a part of the wall of the cylindrical part on which the winding is performed in the core of the coil wound around the core. (3) An opening is provided in the wall of the cylindrical part at the position where the interval between each core is the shortest in the winding core for multiple coils that are wound around a plurality of adjacent cores. 2. The coil bobbin for electromagnetic components according to item 2 above. (4) A coil bobbin for electromagnetic components, characterized in that the surface in contact with the conductor to be wound is a winding core member made of a metal material with good heat conductivity and subjected to conductive insulation treatment.