JPS5938007Y2 - Molded electromagnetic coil - Google Patents

Description

[Detailed description of the invention] The present invention improves the moldability of electromagnetic coils used in electromagnets, more specifically, molded electromagnetic coils in which the outside of the coil is coated with resin. .

FIG. 1 is a front view of a conventional molded coil.

FIG. 2 is a sectional view taken along the line AA' in FIG. 1, or more precisely, a sectional view along the line AA' showing the state during molding.

1 is a bobbin molded in advance from resin, and a coil 2 is wound around the outer periphery of the bobbin.

The outside of the coil 2 is covered with an exterior resin 3 formed by molding.

Terminals 4 and 4' are inserted and fixed at the ends of the bobbin and are filled with the resin 3 and molded while being connected to the coil terminals.

When molding the exterior resin 3, the bobbin 1 on which the coil 2 is wound and the terminals 4, 4' are attached is set in a cylindrical space formed by the molds 5, 5', and the space is filled with resin. By doing so, the outer cover 3 is molded.

However, during this filling operation, the resin was mixed into bobbin 1, mold 5,
It enters the gap between 5' and wraps around the bobbin inner wall 1 from the end of the bobbin 1. 731, 32, 31', 32', etc. may occur.

These pads cause dimensional changes in the finished product, so they must be removed for finishing.

Normally, resin is measured and filled in order to prevent such particles from occurring, but the volume of the coil section 20 may fluctuate due to variations in the wire diameter of the coil being wound or differences in the winding state of the coil. However, because of this, the volume of the space to be filled with resin changes, so if the amount of resin is too large for the space, it will enter the gap and cause damage as described above.

If the amount of resin filled in the space is small, the filling will be insufficient.

Normally, it is filled in winter to avoid insufficient filling, but in this case, there is an unavoidable gap between bobbin 1 and molds 5 and 5' due to the convenience of cutting the mold after molding, and bobbin 1 Due to deformation such as warping of the material itself, dimensional errors, gas vent holes in the mold, etc., it is impossible to prevent the resin from being squeezed into the bobbin as described above.

However, in the pushinger type electromagnetic coil, a thin plunger guide sleeve is inserted into the bobbin hole 1', so the debris inside the bobbin hole must be removed. It is desirable to prevent the occurrence of Paris in advance.

The present invention solves these conventional problems by devising a bobbin, and realizes an electromagnetic coil that is free from the risk of generation of cracks.

Next, details of the electromagnetic coil according to the present invention will be explained based on illustrated embodiments.

3 and 4 show the electromagnetic coil according to the present invention as shown in FIG.
FIG. 2 is a diagram corresponding to FIG. 2;

In the case of the present invention, ring-shaped grooves 11 and 12 are formed in advance on both left and right end surfaces of the bobbin 1.

First, grooves 11 and 12 are formed on both end faces of the bobbin so as to surround the bobbin hole 1.

The molds 5 and 5' for molding are exactly the same as the conventional ones, and when filling, taking into account variations in the space to be filled with resin, we use a casing that matches the minimum volume or a resin that is slightly older than that. Weigh and fill.

Then, since there are grooves 11 and 12 between the exterior resin 3 and the bobbin hole inner wall 1' on both end faces of the bobbin,
Excess resin that exceeds the space to be filled with resin flows into the grooves 11 and 12 through the gap between the end face of the bobbin and the mold 5 and is collected therein.

Then, excess resin overflows from the grooves 11 and 12,
The concave groove 11,
12, the flow of excess resin is stopped by the grooves 11 and 12, and does not go around the bobbin hole inner wall 1' side 1.

As described above, according to the present invention, since the annular grooves 11.12 surrounding the bobbin hole 1' are provided in advance on both end faces of the coil bobbin 1, excess resin is absorbed into the grooves 11.12.

Therefore, there is no risk that the resin will wrap around the inner wall 1'1 of the bobbin hole and cause a change in the dimensions of the bobbin hole 1, and there is no need to remove the resin.

The excess resin is absorbed by the concave grooves 11 and 12, and there is no risk of causing cracks, so it is possible to accommodate volume variations in the coil part 2 with a margin, which makes the design easier and improves product yield. improves.

Note that, as shown in the illustrated example, it is preferable that the groove is continuous and annular, but even if it is intermittent, the effect of Kanashi can be obtained as long as the excess resin can be absorbed.

In some cases, it is sufficient to have a groove on only one side of the bobbin.

Further, if a plurality of concave grooves are provided in a concentric manner, the layer is effective.

[Brief explanation of drawings]

FIG. 1 is a front view of a conventional electromagnetic coil, and FIG. 2 is a sectional view taken along the line A--A in FIG. 1, showing a state during molding. FIG. 3 is a front view of the electromagnetic coil according to the present invention, and FIG. 4 is a sectional view taken along the line A--A in FIG. 3, showing the state during molding. In the figure, 1 is the coil bobbin, 1 is the bobbin hole (inner wall)
, 11.12 is a groove for absorbing excess resin, 2 is a coil, 3 is an exterior resin, 31.32.31. 32' is a mold, and 5 and 5' are molds for molding.

Claims (1)

[Scope of utility model registration request] The outer side of the coil wound around the bobbin is coated with resin in an electromagnetic coil, and at least one side of the coil bobbin is provided with a recess for absorbing excess resin when filling and molding the coil's exterior resin. A molded electromagnetic coil characterized by being formed in advance so as to surround a hole.