JPH0128645Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a rotating transformer that transmits and receives electrical signals while being driven in relative rotation. Regarding trance.

《Background of the idea》 A rotary transformer has a groove formed on the opposing surface of the transformer core, and a disk-shaped coil coated with an insulator such as enamel is fixed with adhesive in the groove. It is designed to send and receive minute electrical signals while rotating the cores relative to each other.

In such a rotating transformer, electrical signals are exchanged through electromagnetic coupling between opposing coils, so it is better to have these coils as close as possible and to minimize the distance between the coil and the transformer core for better electromagnetic coupling. Desirable as it increases strength. However, in the above-mentioned conventional rotary transformer, the coil is housed in the groove, so the groove needs to be formed with a margin larger than the width and height of the coil in consideration of the work of inserting the coil. Furthermore, since the coil is fixed in the groove of the transformer core using a non-magnetic adhesive such as epoxy, a non-magnetic material is interposed between the coil and the transformer core, which prevents electromagnetic coupling between the two. There was a problem in that the number of turns in the coil had to be increased to obtain a predetermined inductance, and as a result, the diameter of the rotating transformer became large.

In order to solve this problem, in the armature of a motor as disclosed in Utility Model Application No. 54-137101, although the technical field is different from that of the present invention, when placing the coil in the slit, a resin containing iron powder is used. It is conceivable to apply the technology using this to rotating coils.

However, in this case, since the iron powder-containing resin is exposed on the surface, there is a risk that the mixed iron powder may fall off from the resin. Then, there is a problem in that the fallen iron powder is scattered inside the transformer and motor, making it unusable.

In particular, the above problem becomes noticeable in the case of a rotary transformer that rotates at high speed during use (operation) and is likely to be subject to centrifugal force on the iron powder.

This idea was devised in view of the above-mentioned problems, and its purpose is to improve the electromagnetic coupling between the coil and the rotating transformer core, thereby reducing the number of turns in the coil and making it more compact. An object of the present invention is to provide a rotary transformer that can prevent mixed magnetic powder from falling out to the outside.

<<Example>> Hereinafter, a preferred example of the rotary transformer according to the invention will be described based on the drawings.

FIGS. 1 and 2 show an embodiment of the rotary transformer of this invention.

As shown in the figure, the rotary transformer is made of a material with high magnetic permeability such as ferrite, and has a plurality of ring-shaped grooves 14 concentrically formed on the flat surface of a transformer core 10 formed in a substantially disk shape. However, a through hole 12 is formed in the center of the transformer core 10.

The dimensions of this groove 14 are formed to be larger than the width and height of the disk-shaped coil 16 housed in the groove 14, and the coil 16 housed in the groove 14 is attached to the adhesive 18. It is twisted and fixed.

Here, in the present invention, the lower layer adhesive 18 is divided into the lower layer adhesive 18 interposed between the coil 16 and the bottom of the groove 12, and the upper layer flowing into the upper side of the coil 16 and disposed so as to cover the lower layer adhesive 18. Adhesive 22-2
It has a layered structure.

The lower layer adhesive 18 is a non-magnetic adhesive such as epoxy or acrylic adhesive mixed with magnetic powder 20 having high magnetic permeability such as iron powder or ferrite. In view of the strength and magnetic permeability, it is preferable to use an adhesive that is made magnetic by mixing 50 to 90% by weight of magnetic powder 20.

In this way, by using an acrylic adhesive, an epoxy adhesive, or the like as the adhesive, it is possible to improve the dispersion of the magnetic powder.

At this time, the lower layer adhesive 18 may be mixed with magnetic powder 20 in advance, or a predetermined amount of the magnetic powder 20 is put into the groove 12, and then the lower layer adhesive 18 is poured. But it doesn't matter.

On the other hand, the upper layer adhesive 22 is a non-magnetic adhesive that does not contain magnetic powder. This suppresses exposure of not only the coil 16 but also the magnetic powder 20 in the lower layer adhesive 18 to the surface.

Note that the transformer core 10 configured as described above is
It can be used for both rotating and stationary transformer cores.

<<Effects of the invention>> As described above, the rotary transformer according to this invention uses a magnetic adhesive mixed with magnetic powder when fixing the coil in the groove. Compared to the conventional method, the dimensions are made to be larger than the width and height of the coil, but since there is an adhesive mixed with magnetic powder between the transformer core and the coil, the electromagnetic coupling is tighter. be able to. As a result, the number of turns in the coil can be reduced to obtain a predetermined inductance, which lowers the direct current resistance of the coil and increases the Q of the coil. In addition, reducing the number of turns reduces stray capacitance and increases the self-resonant frequency, etc.
The electrical characteristics of the rotating transformer can be improved. Furthermore, since the number of turns in the coil is small, the rotating transformer core can be made smaller while maintaining or improving conventional characteristics.

Furthermore, in this invention, the adhesive has a two-layer structure, and the upper layer adhesive is a non-magnetic adhesive that does not contain magnetic powder, so the magnetic powder in the lower layer adhesive is removed due to centrifugal force generated during use of the rotary transformer. Even if the magnetic powder moves toward the magnetic powder and tries to fall off from the adhesive, the upper layer adhesive located above can prevent the magnetic powder from falling off.

This allows stable use of the rotary transformer over a long period of time.

Further, this upper layer adhesive can provide the effect of increasing the adhesive strength between the coil and the rotating transformer core.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a rotary transformer according to the present invention, and FIG. 2 is an enlarged sectional view of a main part in FIG. 10...Transformer core, 14...Concave groove, 16...
... Coil, 18 ... Lower layer adhesive, 20 ... Magnetic powder, 22 ... Upper layer adhesive.

Claims (1)

[Scope of utility model registration request] A ring-shaped groove is provided on the opposing surfaces of a pair of transformer cores made of a ring-shaped material with high magnetic permeability such as ferrite, and electrical signals are transmitted and received in a non-contact manner while rotating relatively within the groove. In a rotating transformer in which a coil is fixed with an adhesive, the adhesive includes a lower adhesive layer interposed between the coil and the bottom of the groove, and an upper layer disposed to cover the lower adhesive layer. The lower layer adhesive is an adhesive into which magnetic powder with high magnetic permeability such as ferrite or iron powder is injected, and the upper layer adhesive is an adhesive in which no magnetic powder is mixed. A rotating transformer featuring