JPS58214216A - Litz wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a litz wire used for high-speed drive coils, low-loss coils, etc., and particularly to a litz wire suitable for obtaining high axiality and high performance.

A conventional litz wire consists of a strand 3 consisting of a conductor 1 and an insulator M2 covering the conductor 1 as shown in FIG.
), after twisting a plurality of strands together, an adhesive layer 4 is provided on the outer periphery of the strands, and the finished outer shape 5 is circular.

The materials used for the insulating layer 2 of the wire 3 are mainly polyester (PEW) and polyurethane (UEW), but these materials have the disadvantage that they cannot sufficiently satisfy moisture resistance and heat resistance at the same time. That is, since polyester undergoes hydrolysis, there is a problem in terms of reliability and moisture resistance.

On the other hand, polyurethane has problems with heat resistance and pressure resistance during post-process molding, and may cause problems such as seams.

In addition, using a Litz wire as shown in Figure 1),
When a two-layer winding drive coil as shown in Figure (a) is assembled, there are problems with high frequency loss and insulation. That is, a sectional view taken along the line A-A in FIG. 2(a) is shown in FIG. 2(b), and a partially enlarged sectional view thereof is shown in FIG. Figure 1 (a) Conductor 1 as shown in K
If the diameter of is de and the finished diameter of the strand 3 is d, it is expressed by the following formula, △d=d-de...
- (1) Δd is determined by the film thickness of the insulating layer 2 of the wire 3.

By the way, in order to increase the speed of the drive coil, it is necessary to reduce the diameter de of the strand conductor of the litz wire in order to reduce high frequency loss due to the skin effect or the like. Finished diameter d of strand 3
Using the film ratio A C>1), d=Ade...4...(2)
From equations (1) and (2),

△d = (A-1) de -=・-=-= (5
)) becomes. The wire used has a strand conductor diameter d
As the film ratio A remains almost constant as e decreases, △d
decreases. As a result, in the drive coil shown in FIG. 2(a), there are problems in that high frequency loss increases and insulation deteriorates due to increased stray capacitance between windings and between layers.

Conversely, if the film thickness of the insulating layer 2 of the wire 3 is increased in order to increase the gap length Δd between windings and between layers, there is a problem that the space factor decreases and the DC resistance increases.

From the above, the various characteristics of drive coils using conventional glue wires structurally depend on the film thickness of the wire insulation layer, and have contradictory tendencies with respect to the film thickness. The situation was such that it was not possible to take sufficient measures to prevent this.

The present invention was invented in view of this situation, and includes (1)
) Improvement in moisture resistance and heat resistance, (2) Increase in space factor, (3)
Reduction of stray capacitance between coil windings and layers.

(4) It is an object of the present invention to provide a litz wire that simultaneously achieves improved insulation between coil windings and between layers.

The present invention focuses on the problem of trying to satisfy all of the various characteristics required of conventional litz wires with the insulating layer of the strand wire. The present invention is characterized in that the above four objects are simultaneously solved by forming two layers: the insulating layer at the stage and the insulating layer newly provided on the outer periphery after the wires are twisted together.

The present invention will be explained below in relation to the above four objectives.

(1) Improving moisture resistance and heat resistance When there is no material that satisfies moisture resistance and heat resistance at the same time as the insulating layer, by using a combination of materials that satisfy each characteristic, that is, using the present invention, it is possible to By using two insulating layers, such as the insulating layer of 1 and the insulating layer of the outer periphery of the litz wire finish, moisture resistance and heat resistance can be improved at the same time.

(2) Increased space factor, reduced stray capacitance between coil windings and layers, and improved insulation By providing two insulating layers as in the present invention, the space factor of Litz wire can be significantly increased compared to conventional technology. This shows that it is possible to increase

FIGS. 4(a) and Φ) are cross-sectional views of the present invention and the prior art Nyorori shoe wire structure, respectively. As a condition, the outer diameter of both Litz wires is D, and the conductor diameter of the strand is 2.

Considering the case where the film thicknesses of the insulating layers: Δa0 are the same, the outer diameter D0 and the conductor diameter deo, which determine the characteristics of the coil, are important parameters given at the time of coil design. Also,
The film thickness Δao of the insulating layer 7 according to the present invention shown in FIG. Think about it by moving from the level to the level of the entire Rikutsu line.

First, the outer diameter of the litz wire. , the conductor diameter de of the wire.

are the same in the present invention and the prior art, so the ratio of each space factor is determined by the number of strands Ma and Mb, and is expressed by the following formula % formula % However, space factor Ma in η1:1 layer light: present invention Number of wires ηb in conventional technology: Space factor Mb in conventional technology There is a relationship between the conductor diameter de of the strand and the following relationship: 2 D=-1g1Ade--(4)β. However, when the number M of strands is 6 or more, the twisting method of the strands is concentric twisting.

The number Ma of strands of the litz wire in the present invention is shown in FIG. 4(a).
Using...=21ゝ・・・・・・・・・・・・・・・(
5) Da=do■kB cieo ・・・・・・・・・
...From (6), we can find.

Similarly, in the case of the prior art shown in Fig. 4 Φ), d-de.

t'aO=2 1'-(Ab-1) ae. −・−・・= (8) Do
= , 1g Abdeo --- From (9), it can be found.

Therefore, the ratio of the space factor η1/ηb is -=(1-1b)2 (1+Silence)2・Soil ηb ・・・・・・・・・・・・・・・・・・(11) Express.

When the space factor ratio ηa/qb shown in equation (11) takes a value of 1 or more, the object of the present invention can be achieved.

From equation (11), the given △a6 @ D6 s d
The coating ratio Aa that makes the ratio η1/ηb of the space factor to eo 1 or more is K as follows.

1 (Aa≦AarnaX ・・・・・・・・・
・・・・・・・・・・・・(12) However, ・・・・・・・・・・・・・・・(16) As an example of the Litz wire used in (Equivalent to J I 8 standard 2nd layer film thickness) deo = 0.0
9 m Do=o, yo' Cao・・・・・・・・・・・・・ Taking up (14), from equation (13), Aamax=1.15 ・・−・・・・・
...(15) is obtained.

Film ratio A is 1.18 for JIS standard type 2 and type 5 cages, respectively.
, 1.13. Therefore, in the present invention, if the coating ratio of the wire insulating layer 2 is t13 (6th type) and the coating ratio of the litz wire finished insulating layer 7 is 1.18 (2nd type), the space factor is The ratio?
The value of a/Wb is 104, and the space factor can be increased.

By the way, in the case of the prior art, the film thickness of the strand insulating layer 2 constituting the litz wire needs to be constant even when the space factor decreases in terms of reliability and characteristics. However, in the case of a structure in which two insulating layers are combined as in the present invention, the coating thickness of the insulating layer 2 of the strands is limited as long as it can ensure the insulation between the strands (between coil windings and between layers). The insulation layer 7 can be satisfied by reducing stray capacitance and improving insulation properties.

On the other hand, since the potential difference between the strands is almost zero due to the characteristics of the litz wire, the coating thickness of the insulating layer 2 of the cable wire may be sufficiently small.

From the above, in the case of a structure in which two insulating layers are combined as in the present invention, it is possible to significantly reduce the film thickness of the insulating layer 2 of the strand, which was impossible in terms of reliability and characteristics with the conventional technology. can.

Therefore, for the condition of formula (14) described above, the value of the coating ratio Aa of the insulating layer 2 of the wire is set in the vicinity of 1.13 to 1 (third
From equation (11), the space factor ratio q*/
'tb can be t3. In other words, it is possible to significantly increase the space factor while improving the reliability and characteristics required of the Litz wire.

The present invention will be explained in detail below.

FIG. 5 shows a first embodiment of the present invention, in which a plurality of strands 3 each having a copper conductor 1 covered with a polyurethane insulating layer 2 are twisted together, a high bond adhesive layer 4 is provided around the outer periphery of the wire, and FIG. 2 is a cross-sectional view of a litz wire having a finished outer shape 5 and whose outer periphery is coated with a polyester insulating layer 7. FIG.

By providing two insulating layers as in this example, the structural degree of freedom is increased by one compared to the conventional technology, so the stray capacitance and insulation between windings and layers are improved by increasing the outer periphery of the litz wire. The number of coating rings of the polyester insulating layer 7 provided is increased, while the space factor is increased by decreasing the number of coating rings of the polyurethane insulation layer 2 of the wire 3, thereby solving the essential problems of the prior art. be able to.

In addition, improvements in moisture resistance and heat resistance include a polyurethane insulation layer 2 with excellent moisture resistance and a polyester insulation layer 7 with excellent heat resistance.
Improved by the 02 layer structure.

FIG. 6 shows a second embodiment of the present invention, and in the embodiment shown in FIG. 5, the film ring of the polyurethane insulating layer 2 is
FIG. 2 is a cross-sectional view of a litz wire having a polyurethane insulating layer 8 having a polyurethane insulating layer 8 of less than Class 3 of the IS standard. By providing two insulating layers and making the film ring of the insulating layer of the wire 3 smaller as in this embodiment, the space factor is significantly increased compared to the embodiment shown in FIG. 4.

FIG. 7 shows a sixth embodiment of the present invention, in which a copper conductor 1 is coated with a polyurethane insulating layer 8, and a bare wire 3 is coated with a thermoplastic resin adhesive layer 9 on the outer periphery. A cross-sectional view of a Litz wire in which a plurality of wires are twisted together, each strand is softened and fused by heating and fixed, a No. It is. As in this embodiment, by providing two insulating layers, reducing the size of the coating ring of the insulating layer of the wire 3, and fixing the wires together, a structure as shown in FIG. 2(a) can be obtained. It has the effect of preventing deformation, especially at the corners, during coil forming.

Note that the polyurethane insulating layer 8 described in FIGS. 6 and 7. The film ring will be explained.

As shown in FIG. 1(a), the diameter of the conductor 1 is de.

The finished outer diameter of the strand 3 made by applying the insulating layer 2 to the conductor 1 is d
Then, the finished outer diameter d is a constant B related to the coating ratio A,
Using m, it is expressed as d=Badem, and in the case of a wire provided with a third insulating layer.

0.93de (d(0,90de [indicated by L88; that is, this region is indicated by U in FIG. 8).

In FIG. 8, the horizontal axis is the conductor diameter de(+a+), and the vertical axis is the finished outer diameter d(,).

The coating ring of less than JI8 standard type 3 shown in FIGS. 6 and 7 is indicated by region ■ in FIG. 8, and the finished outer diameter d in this case is de< d≦0. 93 de
It is expressed as 1lL95.

According to the present invention, (1) improved moisture resistance and heat resistance; (2)
We provide high-performance, high-reliability Litz wires that can simultaneously increase space factor, (6) reduce stray capacitance between coil windings and between layers, and (4) improve insulation between coil windings and between layers. This makes it possible to solve the problem of increasing the speed of the drive coil, which has been considered difficult in the prior art.

[Brief explanation of drawings]

FIG. 1(a) and FIG. 1Φ) are cross-sectional views of a strand and a litz wire that constitute a conventional litz wire. FIG. 2(a) is a perspective view of a driving coil formed using a Litz wire, FIG. 2(b) is a sectional view taken along the line A-A in FIG. 2(a), and FIG. FIG. 2 is an enlarged cross-sectional view of a part of FIG. FIGS. 4(a) and 4(b) are partially enlarged sectional views of the present invention and the conventional litz wire, respectively. 5, 6 and 7 are cross-sectional views of six embodiments of the litz wire according to the invention. FIG. 8 is a diagram showing the relationship between the conductor diameter and the finished outer diameter of the wire. 1... Conductor 2... Element wire insulating layer 3... Element wire 4... Litz wire adhesive layer 7... Litz wire insulating layer 9... Element wire adhesive layer O 1 Figure 2; t 3m Dabutsuo 4 Figure (0-](b)

Claims (1)

[Claims] t. A Litz wire consisting of a plurality of wires provided with an insulating layer, characterized in that a layer of an insulating film is provided on the finished outer periphery after the wires are twisted. Ritz wire. 2. The coating thickness of the insulating layer of the above wire is de(d≦0.93 de O5'5, where de: conductor diameter of the wire, d: thickness that satisfies the finished outer diameter of the wire including the insulating layer) A glue wire according to claim 1, characterized in that: