JPS6219098Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voice coil for a motor, particularly a linear motor.

A linear motor 1 as shown in FIGS. 1 and 2 is used in a drive section of a magnetic disk memory device of a computer. This linear motor 1 has advantages such as accurate positioning, fast response speed, and miniaturization because no mechanical device is involved in reciprocating motion. Next, the components of the linear motor 1 will be explained with reference to FIGS. 1 and 2.

1 shows the overall configuration of a linear motor. 2 is a permanent magnet, 3A and 3B are yokes made of a material with high magnetic permeability, and 4 is a flow of magnetic flux, which flows as shown by the arrow. Reference numeral 5 denotes a gap in the magnetic circuit, and 6 a voice coil passing through the gap 5, which is comprised of a support fitting 7, a bobbin 8, and a coil 9. When a current flows through the coil 9, a force is generated in the axial direction according to Fleming's left-hand rule, and the voice coil 6 moves. The direction of movement is inside or outside depending on the direction of current flow.
At this time, the voice coil 6 moves inward or outward at high speed with a load of several kilograms, so it requires strength in the axial direction. Therefore, the support fitting 7, bobbin 8, and coil 9 that constitute the voice coil 6 must be able to sufficiently withstand this load and must not cause separation. For this purpose, a sufficient bonding area is required at the joint of the voice coil 6, particularly at the joint between the bobbin 8 and the coil 9.
On the other hand, in order to efficiently obtain high thrust, the gap 5 must be made as small as possible and the magnetic resistance must be reduced. The magnetic resistance is R, the radial length of the air gap 5 is l,
If the cross-sectional area of the magnetic flux path is S, and the magnetic permeability of the magnetic circuit is μ, then from the formula R=l/μS, if l is made smaller, R will also be smaller. In this way, in order to obtain a sufficient adhesive cross-sectional area between the constituent members of the voice coil 6, the thickness of the coil is increased, and the length of the gap 5 in the radial direction is increased.On the other hand, in order to obtain a high thrust, On the other hand, there are conflicting factors such as the need to reduce the radial length of the air gap 5 and the need to reduce the thickness of the voice coil 6. In addition, as a factor that determines the dimensions of the gap 5, a space for the parallelism of the linear motor 1 and the voice coil 6 is required in order for the voice coil 6 to move in and out of the gap. However, at present, the dimensions of the air gap 5 are kept close to the limit using the best processing technology, and efforts are being made to reduce the thickness of the voice coil 6.

By the way, in order to reduce the thickness of a conventional voice coil for a linear motor, as shown in FIG. 3, a bobbin 8 made of an insulating material that joins the coil 9 and the support fitting 7 is butt-bonded at the end face 10. However, with this structure, the adhesion area of the end face 10 was small and sufficient strength could not be obtained. Further, in order to improve this point, as shown in FIG. 4, the abutting surfaces 11 of the bobbin 8 and the coil 9 are bonded to each other in an uneven manner. However, even with this structure, the mechanical strength of the abutting surfaces 11 was insufficient, and there was a risk of breakage when the load increased.

This invention increases the adhesive strength between the coil and the bobbin made of insulating material without increasing the thickness of the voice coil.
The purpose of the present invention is to provide a voice coil in which there is some space in the air gap between the coil's entrance and exit.

The present invention will be described below with reference to embodiments shown in the drawings.

Figure 5 shows the main part of one embodiment of the present invention, that is, Figure 4A.
This is a sectional view of a portion corresponding to the section, in which the same parts as in FIGS. 3 and 4 are given the same reference numerals. The bobbin 8 made of an insulating material has a butting surface 11 with the coil 9.
The outer circumferential side is concave and the inner circumferential side is convex. On the other hand, the coil 9 is made of a plurality of spirally wound flat electric wires having an insulating coating such as enamel paint on the outer periphery and fixed with adhesive. has a cross section of The bobbin 8 and the coil 9 are formed so that their end faces fit neatly together when abutted against each other.

Therefore, the bobbin tip surface 1 at the abutting surface
A reinforcing film 13 is placed between the layers at the end of the coil that spans the
is interposed and fixed to the coil with adhesive.

The reinforcing film 13 is made of a plastic tape made of polyester, polyimide, etc., which has a breaking strength of 2 kg/mm ² or more, has good adhesion to adhesives, and has a thickness in the range of 10 to 200 microns. If the film 13 has a wall thickness of less than 10 microns, the breaking strength is insufficient, and if it exceeds 200 microns, it is too thick and the outer diameter of the coil increases. Preferably, the wall thickness is in the range of 30 to 100 microns, and the width is at least as large as the wall thickness of the butt surface 11.
Preferably 1.5 times as long.

The reinforcing film 13 may be disposed so as to straddle the bobbin tip end surface 12 at the abutting surface, and therefore, a portion thereof may be arranged along the end of the bobbin 8 as shown in FIG.

As described above, the motor voice coil according to the present invention is
By bonding the abutting surfaces of the bobbin and coil with irregularities and interposing a reinforcing film between the layers of the coil end that spans the bobbin tip surface on the abutting surface, the outer diameter of the coil hardly increases. , the breaking strength of the abutting surface is extremely high. For this reason, as shown in FIG.
When incorporated into B, the air gap 5 can be minimized and the thrust force can also be increased. In particular, since the thrust increases with the square of the length of the air gap 5, this effect is significant.

In addition, in this invention, since the coil is made of flat electric wires, the contact area between the wires in the coil is larger than that of a coil made of round electric wires, and the bonding density is high. Therefore, there is no need to interpose a reinforcing film in the coil. Therefore, the present invention maintains the desired mechanical strength by interposing a reinforcing film made of plastic with good adhesive properties such as polyester or polyimide only at the butt part between the coil and the bobbin, and also makes it possible to maintain the desired mechanical strength during processing. This has the effect that the time-consuming work of interposing a reinforcing film can be largely omitted.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a linear motor, Fig. 2 is a front view of Fig. 1, Figs. 3 and 4 are sectional views showing conventional voice coils, and Fig. 5 is an embodiment of the present invention. FIG. 6 is a sectional view showing another embodiment of the present invention. 7... Support metal fittings, 8... Bobbin, 9... Coil, 11... Butt surface, 13... Reinforcement film.

Claims (1)

[Scope of utility model registration request] A coil formed by spirally winding a flat electric wire with an insulating coating on the outer periphery into multiple layers and fixing each layer with adhesive, and a bobbin made of an insulating material, and a bobbin made of an insulating material. Between the layers at the end of the coil that straddles, there is a wall thickness of 10~
A voice coil for motors characterized by interposing a reinforcing film made of 200 micron plastic tape that has good adhesion to adhesives such as polyester and polyimide.