JPH08238326A - Primary side core of transformer for contactless energy transmissoin system - Google Patents

Abstract

PURPOSE: To make it possible to suppress raising in the temp. of a transformer to be used for percutaneous charging system for a pace maker and to improve the efficiency of a charging system by preventing the overcurrent of a primary side core of this transformer. CONSTITUTION: The surface facing the secondary core of a circumferential outer leg 14 of the primary side core 16 is provided with an expanded width part 15 expanded in an inner circumferential direction. This expanded width part 15 is radially provided with many slits 21 from its center. The eddy current of the expanded width part 15 is prevented by these slits 21, by which the efficiency of the system is improved and heat generation is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the shape of a transformer used in a charger such as an implantable cardiac pacemaker which transmits electric power with a large gap between the primary side and the secondary side of the transformer. , Especially the shape of the primary core of the transformer.

[0002]

2. Description of the Related Art FIG. 3 shows an outline of a transcutaneous charging system for a cardiac pacemaker. In the same figure, the part surrounded by the chain line shows the pacemaker (A) and is embedded in the body.
A pulse generator 1 that generates pulses, a secondary battery 2 that is a power source thereof, and the like are housed therein.

The pulse signal generated by the pulse generator 1 is transmitted to the heart 4 through the electrode lead 3 and causes the heart 4 to pulsate regularly.

Further, a high frequency inverter 5 is installed outside the body to excite the primary coil 6 of the transformer, and power is transmitted to the secondary coil 7 of the transformer housed inside the pacemaker (A) in the body. To do.

The voltage generated in the secondary coil 7 is exchanged for direct current by the rectifier circuit 8 to charge the battery 2. Between the primary side coil 6 and the secondary side coil 7, there is skin 9, fat or the like. Therefore, the primary coil 6 and the secondary coil 7 are 10 m
Energy must be transmitted over large intervals of m or more.

As described above, when there is a large gap between the primary side coil and the secondary side coil, the coil is made as large as possible to increase the area where the primary side coil and the secondary side coil face each other. If not, the coupling ratio between the primary side and the secondary side cannot be increased.

However, since the secondary coil is housed inside the pacemaker, it is necessary to make the volume as small as possible, and as shown in FIGS. 4A and 4B, the secondary core 11 is The secondary coil 7 is made of a disk-shaped thin amorphous material, and is made into a very thin shape by winding a thin wire rod of about 0.1 mm in a spiral shape.

On the other hand, in the conventional primary side coil 6, as shown in FIG. 5, the central middle foot 13 and the surrounding outer foot 14 are provided on one surface side of the disk-shaped portion 12, and the outer foot 14 is A primary side core 16 is formed by forming a disk-shaped widened portion 15 in which the surface facing the secondary side core is expanded inward to form the primary side core 1.
6 has a structure in which the primary coil 6 is arranged in a space surrounded by the outer legs 14 of 6 and the widened portion 15.

The primary coil 6 and the secondary coil 7 are
As shown in FIG. 5, they are arranged so as to face each other with their central axes aligned. By arranging in this way, the primary coil 6 is excited by passing a current through the primary coil 6, and the secondary coil 7 is excited.
Transfer magnetic flux to.

FIG. 6 shows the directions of magnetic flux. Primary coil 6
The magnetic flux generated in the middle leg 13 of the core 16 is transmitted to the vicinity of the center of the core 11 in the secondary coil 7, and is expanded from the peripheral portion of the secondary core 11 to the outer leg 14 of the primary core 16. Proceed to. Then, the primary side core 16 returns to the middle leg 13 via the outer leg 14 and the bottom disk-shaped portion 12.

[0011]

As described above, even in the conventional transformer, the magnetic flux can be transmitted from the primary side coil 6 outside the body to the secondary side coil 7 disposed inside the body, and the secondary side coil 7 can be transmitted to the secondary side coil 7. Power can be transmitted.

However, in the structure in which the core 16 of the primary coil 6 is provided with the widened portion 15 on the outer leg 14, a large eddy current flows in the widened portion 15 in the direction shown by the arrow as shown in FIG. The heat generated by this eddy current causes a temperature rise in the widened portion 15, and sometimes causes low-temperature burns to the human body.

In addition, the power loss due to the eddy current causes a decrease in efficiency of the transdermal charger.

Therefore, an object of the present invention is to prevent the eddy current from flowing in the widened portion of the primary side core, to prevent the temperature rise and to increase the coupling rate between the primary side coil and the secondary side coil. It is to provide a primary side core of a transformer for a non-contact energy transmission system that can be used.

[0015]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a secondary outer peripheral foot portion of a primary core.
The surface facing the next core is formed in a disk-shaped widening portion that is expanded inward or outward, and slits are provided in the widening portion in a radial arrangement from the center.

[0016]

Since slits are provided radially from the center in the widened portion of the primary side core, the slits cut off the path of the eddy current that tends to occur in the widened portion, and the eddy current can be greatly reduced. It is possible to suppress the temperature rise of the part. Further, the slit does not obstruct the flow of the magnetic flux, and the efficiency of the percutaneous charger can be improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 of the accompanying drawings.

In the first embodiment shown in FIG. 1, the primary side core 16 has a center midfoot 13 and an outer foot 14 around the central foot 13 on one side of a disk-shaped portion 12 made of ferrite.
A disk-shaped widening portion 15 that is expanded inward is provided on the surface facing the secondary side core, and a large number of slits 21 are provided in the widening portion 15 radially from the center. The primary side coil 6 is wound around the center midfoot 13 of the primary side core 16.

The arrow shown in FIG. 1B indicates the direction of the magnetic flux flowing in the widened portion 15. The slit 21 interrupts the path of the eddy current, and the magnetic flux is radiated from the center of the widened portion 15. Flowing. Therefore, even if the slit 21 is formed in the widened portion 15 as described above, the flow of the magnetic flux is not prevented, and the energy can be smoothly transferred to the secondary side core by the magnet. In this way, slit 2
When 1 is entered, the flow of magnetic flux is not hindered and the eddy current can be greatly reduced.

2A and 2B show a second embodiment, in which the widened portion 15 is expanded inward in the first embodiment, whereas the widened portion 15 is expanded in this second embodiment. 15 is expanded outward from the outer foot 14, and a large number of slits 21 are radially provided in the widened portion 15 from the center to the outside.

Also in the second embodiment, as in the first embodiment, the eddy current can be greatly suppressed without obstructing the flow of the magnetic flux, and the improvement of efficiency and the suppression of heat generation can be realized. it can.

Next, the experimental results of the effect of the slit in the shape of the second embodiment shown in FIG. 2 are shown in the table.

In FIG. 2, the diameter (D) of the disk-shaped portion 12 is 36 mm, and the dimension (a) of the widened portion 15 is 7 mm.
The core iron loss was measured in two cases of mm and 17 mm.

When the size (a) of the widened portion 15 was 7 mm and the transformer was excited so that the iron loss was 100 mW without the slit, the iron loss was reduced to 84 mW when the slit was inserted.

The dimension (a) of the widened portion 15 is 17 m.
In the case of m, when the transformer was excited so that the core loss was 100 mW without the slit, the core loss was reduced to 76 mW when the slit was inserted.

[0026]

[Table 1]

As described above, when the slit is provided in the widened portion, the loss can be reduced by about 20%.

The present invention can be applied not only to the above-mentioned percutaneous charging system for pacemakers, but also to general systems such as artificial hearts that transmit electric power from outside the body to the body via magnetic flux. it can. Furthermore, for example, it can be used for all systems that transmit power in a non-contact state such as charging of a secondary battery of a portable device.

[0029]

As described above, according to the present invention, it is possible to effectively prevent eddy currents without obstructing the flow of magnetic flux from the primary side core to the secondary side core. It is possible to improve the efficiency and suppress heat generation of the contactless energy transmission system.

[Brief description of drawings]

1A is a vertical sectional front view showing a first embodiment of a primary core according to the present invention, and FIG. 1B is a bottom view of the same.

FIG. 2A is a vertical sectional front view showing a second example of the primary core, and FIG. 2B is a bottom view of the same.

FIG. 3 is a circuit diagram showing an outline of a transcutaneous energy transfer system for a cardiac pacemaker.

FIG. 4A is a side view showing a conventional secondary coil,
(B) is a bottom view of the same.

FIG. 5 is a vertical sectional side view showing a conventional primary coil and secondary coil.

FIG. 6 is a vertical cross-sectional side view showing the flow of magnetic flux of the primary side core and the secondary side coil.

FIG. 7 shows a conventional primary core, (A) is a vertical side view, and (B) is a bottom view showing the eddy current of the same.

[Explanation of symbols]

 6 Primary coil 7 Secondary coil 12 Disc-shaped part 13 Center middle foot 14 Outer foot 15 Widened part 16 Primary core 21 Slit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuya Hirachi 1500 Inoguchi, Nakai-cho, Ashigarashami-gun, Kanagawa Inside the Cardio Pacing Research Laboratory Co., Ltd. (72) Yasushi Maejima 5 Techno Park, Mita City, Hyogo Prefecture 4 Tabuchi Denki Within the corporation

Claims (1)

[Claims] 1. A primary side coil in which a primary side coil is wound around a center midfoot and a secondary side core in which a secondary side coil is wound in a flat plate shape are arranged in a non-contact manner. The primary side of the transformer for the non-contact energy transfer system that transmits the magnetic flux induced in the secondary side core to the secondary side core from the center midfoot of the primary side core through the surrounding outer foot part. In the core, a surface of the outer peripheral portion of the primary side core facing the secondary side core is formed in a disk-shaped widening portion that is expanded inward or outward, and slits are radially arranged from the center in the widening portion. The primary core of the transformer for the non-contact energy transmission system, which is characterized by being provided.