JP2002025837A - Rotary joint for transmitting electric power - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily make the paired ferrite cores of a rotary joint for transmitting electric power to face each other. SOLUTION: Ferrite cores (15 and 16) of rotation- and stationary-side ferrite core units are made to face each other, so as to form an annular empty room (17) between the cores (15 and 16) and coils (18 and 19) of both ferrite core units are housed in the empty room in a facing state, so as to generate an induced electromotive force on the rotary ferrite core unit side by the electromagnetic induction between both ferrite core units. By combining two cylindrical core sections (20a and 20b) doubly surrounding a rotating shaft (10) with two discoid core sections (21a and 21b), both ferrite cores (15 and 16) and the annular empty room are formed and gaps (22a and 22b) for rotation are formed among the end faces (A, B, C, and D) or among peripheral surfaces (E, F, G, H, I, and J) of prescribed rotation- and stationary-side core sections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rotary joint for power transmission.

[0002]

2. Description of the Related Art Conventionally, in order to transmit power without contact between a stationary body and a rotating body, a rotary joint for power transmission utilizing electromagnetic induction (mutual induction) is used.

As shown in FIG. 9, a rotary joint for power transmission includes a rotating core unit fixed to a rotating body 2 including a rotating shaft 1, and a stationary body 3 stationary with respect to the rotating shaft 1.
And a stationary-side core unit fixed to the main body. The cores 4 and 5 of both core units are arranged to face each other so as to form an annular space between the cores, and the coils 6 and 7 of both core units are housed in the annular space so as to face each other. Due to the electromagnetic induction between the two core units, an induced electromotive force is generated in the rotation side core unit. That is, the stationary side coil 7
When a high-frequency pulse is applied to the, the magnetic flux goes around from the stationary side core 5 to the rotating side core 4, and a current is generated in the rotating side coil 6. Thus, for example, power is supplied to the electronic device on the rotating body 2 side, and the electronic device on the rotating body 2 side transmits information on the rotating body 2 from the transmission antenna 8 to the receiving antenna 9 on the stationary body 3 side.

Further, by using ferrite cores as the conventional cores 4 and 5, the effect of concentrating magnetic flux is enhanced, and efficient transmission is performed. The use of pot-type ferrite cores as shown in FIGS. 9 and 10 as the cores 4 and 5 prevents leakage of magnetic flux, facilitates passage of magnetic flux, and enhances transmission efficiency. The pot type ferrite core has a shaft hole through which the rotating shaft 1 passes, and has an annular groove around the shaft hole for accommodating the coils 6 and 7. The end faces 4a, 4b, 5a, 5b of the two annular walls serving as the banks of the annular groove face each other between a pair of pot-type ferrite cores, and allow a magnetic flux of electromagnetic induction to pass therethrough.

[0005]

A pot-type ferrite core having good dimensional accuracy can be obtained even if it undergoes a forming step and a firing step, if the outer diameter is about several tens of mm.

However, when the transmission power is increased or when it is necessary to increase the inner diameter of the hollow portion, the outer diameter of the pot type ferrite core must be increased. In this case, the ferrite core may be deformed in the firing process or the like,
Because of shrinkage, dimensional accuracy decreases. For this reason, the dimensional accuracy is increased by forming, sintering, and cutting and polishing in the post-processing so as to be larger than the target size in advance.

[0007] However, cutting and polishing cannot be performed unless the thickness is reduced by a small thickness. In addition, in the pot type shape, cutting of the outer diameter, inner diameter, height part,
Polishing is possible, but it is difficult to cut and polish the inner periphery of the annular groove.

For this reason, a large pot type ferrite core has a poor product yield and is very expensive.
When such a pot-type ferrite core is used as a pair to be used for transmission of a power supply or the like, the end faces 4 of the two annular walls are used to prevent leakage of magnetic flux and increase transmission efficiency.
a, 4b, 5a, and 5b must be precisely aligned, further reducing the yield.

An object of the present invention is to provide means for solving the above problems.

[0010]

In order to solve the above problems, the invention according to claim 1 is fixed to a rotating body (13) including a rotating shaft (10) as shown in FIGS. Rotating ferrite core unit (11) and rotating body (1
3) a stationary ferrite core unit (12) fixed to a stationary body (14) that is stationary with respect to the ferrite core (1) of both ferrite core units (11, 12).
5, 16) are opposed to each other so as to form an annular space (17) between both ferrite cores (15, 16), and both ferrite core units (11, 1) are provided in the annular space (17).
2) The coils (18, 19) are housed so as to face each other, and the ferrite core unit (11) on the rotating side is rotated by electromagnetic induction between the ferrite core units (11, 12).
In a rotary joint for power transmission in which an induced electromotive force is generated on the side, two different-diameter cylindrical core portions (20a, 20b) surrounding the rotating shaft (10) doubly and two disks of the same shape The ferrite cores (15, 16) and the annular space (17) are formed by combination with the cores (21a, 21b), and a predetermined core fixed to the rotating body (13) and the stationary body A rotation gap (22a) between end faces (A, B, C, D) with a predetermined core portion fixed to (14) or between peripheral faces (E, F, G, H, I, J). , 22b) are formed.

According to a second aspect of the invention, as shown in FIG. 2 or FIG.
Are the disk core part (21b) and this disk core part (21b)
And the other ferrite core (15) is formed of a small-diameter cylindrical core portion (20b) joined to the disk core portion (21a).
And a large-diameter cylindrical core portion (20a) joined to the disc core portion (21a), and one disc core portion (21a) is formed.
Between the end surface (A) of the first cylindrical member and the end surface (D) of the small-diameter cylindrical core portion 20b, and the end surface (C) of the other disk core portion (21b) and the end surface (B) of the large-diameter cylindrical core portion (20a). The rotary joint for power transmission according to claim 1, wherein the gaps (22a, 22b) are formed between the gaps.

According to a third aspect of the present invention, as shown in FIG. 4, the one ferrite core (16) is formed only of the disk core portion (21b) and the other ferrite core (15) is formed of the disk. The core portion (21a) and the large-diameter cylindrical core portion (20a) and the small-diameter cylindrical core portion (20b) joined to the disc core portion (21a) are formed, and the disc core portion (16) which is one ferrite core (16) is formed. 21b) and the gaps (22a, 22b) between the end surfaces (B, A) of the large-diameter cylindrical core portion (20a) and the small-diameter cylindrical core portion (20b) of the other ferrite core (15). ) Is formed, and the rotary joint for power transmission according to claim 1 is adopted.

According to a fourth aspect of the present invention, as shown in FIG. 5 or FIG. 6, the one ferrite core (15) is formed only of a large-diameter or small-diameter cylindrical core portion (20a or 20b), and the other is formed. Ferrite core (16) is formed of a small or large diameter cylindrical core portion (20b or 20a) and two disk core portions (21a, 21b) coupled to the small or large diameter cylindrical core portion (20b or 20a). The outer peripheral surface (E or H) of the large-diameter or small-diameter cylindrical core portion (20a or 20b) of one ferrite core (15) and the two disk core portions (21a, 21b) of the other ferrite core (16). The clearance (22) between each peripheral surface (E, F, G, H, I, J)
The rotary joint for power transmission according to claim 1, wherein a, 22b) is formed.

According to a fifth aspect of the present invention, as shown in FIG. 2 or FIG. 4, a coil (18) of the rotating ferrite core unit (11) and a coil (18) of the stationary ferrite core unit (12) are provided. The rotary joint for power transmission according to any one of claims 1 to 4, wherein the end faces (18a, 19a) face each other.

Further, the invention according to claim 6 is the same as that shown in FIGS.
Alternatively, as shown in FIG. 6, the coil (18) of the rotating-side ferrite core unit (11) and the coil (19) of the stationary-side ferrite core unit (12) have their circumferential surfaces (18b, 19b) connected to each other. The power transmission rotary joint according to any one of claims 1 to 4 provided so as to face each other.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> As shown in FIG. 1 and FIG. 2, this power transmission rotary joint
And a stationary ferrite core unit 11 fixed to a stationary body that is stationary with respect to the rotating body.

The rotating shaft 10 is a shaft such as a rotor or a roller. The rotating body and the stationary body are respectively composed of a rotating supporting plate 13 and a stationary supporting plate 14 made of metal. The rotation support plate 13 is fixed to a rotor, a roller, or the like, and the stationary support plate 14 is fixed to a housing, a frame, or the like. Both support plates 13, 1
Numeral 4 is preferably a non-magnetic material such as aluminum, brass, stainless steel or the like, and is formed in a disk shape. Since the support plates 13 and 14 are made of a non-magnetic material, heat is less likely to be generated due to magnetic flux leakage, and the ferrite core units 11 and 12 are connected to the support plate 1.
The adhesive for fixing to 3 and 14 is not deteriorated.

The ferrite core units 11 and 12 on the rotating side and the stationary side have ferrite cores 15 and 16, respectively.
One ferrite core 15 is fixed to the rotating support plate 13, and the other ferrite core 16 is fixed to the stationary support plate 14. An annular space 1 is provided between the ferrite cores 15 and 16.
7 are formed, and coils 18 and 19 are formed in the annular space 17.
Are arranged facing each other, one coil 18 is fixed to the rotating ferrite core 15, and the other coil 19 is fixed to the stationary ferrite core 16.

The two ferrite cores 15 and 16 and the annular space 17 are formed of two cylindrical cores 20 a and 20 b having different diameters and surrounding the rotating shaft 10, and two disk cores 21 of the same shape.
a, 21b. In particular,
The rotating ferrite core 15 is formed of a disc core 21a and a large-diameter cylindrical core 20a coupled to the disc core 21a, and the stationary ferrite core 16 is formed of the disc core 2
1b and a small-diameter cylindrical core portion 20b connected to the disk core portion 21b. In the rotation-side ferrite core 15, one end surface of the disk core portion 21a is fixed on the rotation support plate 13 with an adhesive or the like, and the disk core portion 2a is fixed.
One end surface of the large-diameter cylindrical core portion 20a is fixed to the other end surface of 1a with an adhesive or the like. Similarly, the stationary side ferrite core 1
6, one end surface of the disk core portion 21b is fixed on the stationary support plate 14 with an adhesive or the like.
One end surface of the small-diameter cylindrical core portion 20b is fixed to the other end surface of the core member b with an adhesive or the like.

Of course, the large-diameter cylindrical core portion 20a and the small-diameter cylindrical core portion 20b can be exchanged between the rotary support plate 13 and the stationary support plate 14. In the illustrated example, the rotating side ferrite core 15 is formed separately from the disk core 21.
a and the large-diameter cylindrical core portion 20a, and the stationary ferrite core 16 is also formed by bonding the separately formed disk core portion 21b and the small-diameter cylindrical core portion 20b separately. The disk core portion 21a and the large-diameter cylindrical core portion 20a of the rotating ferrite core 15 are integrally formed in a state of being joined together from the beginning, and the stationary ferrite core 1 is formed.
6 may be formed integrally with the disc core portion 21b and the small-diameter cylindrical core portion 20b joined together from the beginning.

Small gaps 22a and 22b are formed between the ferrite cores 15 and 16 to allow the rotation of the rotary support plate 13 with respect to the stationary support plate 14. That is, the end faces A and B of the disk core portion 21a and the large-diameter cylindrical core portion 20a fixed to the rotation support plate 13 and the stationary support plate 14a.
Core portion 21b and small-diameter cylindrical core portion 20 fixed to
b are opposed to each end face C, D via gaps 22a, 22b. The end faces A, B, C, and D that face each other through the gaps 22a and 22b face each other without deviation, and therefore, no leakage occurs in the magnetic flux passing through the path indicated by the broken line. In order to obtain desired electromagnetic induction characteristics in power transmission, the size of the gaps 22a and 22b needs to be uniform over the entire circumference of the ferrite cores 15 and 16. However, the end faces of the cylindrical core portions 20a and 20b are required. The purpose can be achieved by polishing B and D. This polishing can be performed simultaneously on a plurality of cylindrical core portions.

As described above, the two ferrite cores 15, 16 and the annular space 17 are formed of two cylindrical cores 20a, 20b having different diameters and surrounding the rotary shaft 10, and two identical disk cores 21a, 21b. The molding and firing of the cylindrical core portions 20a, 20b and the disc core portions 21a, 21b are easier and easier to manufacture than conventional pot type ferrite cores. Further, the core parts 20a, 20b,
In order to match the end faces A, B, C, D of 21a, 21b to each other, the cylindrical core portions 20a, 20b and the disc core portions 21a, 2
It is sufficient to cut or polish the inner or outer peripheral surface of 1b. Therefore, the yield of the ferrite cores 15 and 16 is improved.

Annular vacancy 1 of both ferrite cores 15, 16
7, a coil 18 of the rotating ferrite core unit 11 and a coil 19 of the stationary ferrite core unit 12 are provided.
And are stored. Each of the coils 18 and 19 is wound in a disk shape and is fixed with a synthetic resin.
a and 19a are fixed to the rotating ferrite core 15 and the stationary ferrite core 16, respectively, such that they face each other. As shown in FIG. 1, cutouts 23 are provided in the ferrite cores 15 and 16, and coils 18,
19 leads are pulled out. Lead wire is for each support plate 1
3 and 14 are connected to power supply connectors 24 and 24 respectively.

In addition, as shown in FIG.
A transmission antenna 25 is attached to the ring 3 so as to surround the rotating shaft 10, and a reception antenna 26 is attached to the stationary support plate 14 so as to face the transmission antenna 25. Signal connectors 27, 27 are attached to the rotating support plate 13 and the stationary support plate 14. Although not shown, for example, a temperature sensor and a processing circuit for detecting the temperature of the roller surface are attached to the rotating shaft 10 side.

Next, the operation of the power transmission rotary joint having the above configuration will be described.

When the rotation shaft 10 rotates, the rotation support plate 13 rotates with respect to the stationary support plate 14. The rotation support plate 13 includes the rotation side ferrite core unit 11 and the transmission antenna 25.
, And the stationary support plate 14 stops at a fixed position while holding the stationary ferrite core unit 12 and the receiving antenna 26.

When a high-frequency pulse is applied to the coil 19 of the stationary-side ferrite core unit 12, the magnetic flux flows from the stationary-side ferrite core 16 to the ferrite core 15 of the rotating-side ferrite core unit 11, and a magnetic flux path indicated by a broken line in FIG. Is secured. A current flows through the coil 18 of the rotation-side ferrite core unit 11 by the electromagnetic induction of the magnetic flux.

Thus, for example, power is supplied to the processing circuit on the rotation side, and the processing circuit becomes operable. The processing circuit transmits the temperature information generated by the rotation-side temperature sensor from the transmission antenna 25. On the stationary side, the receiving antenna 26 receives the temperature information and sends it to a predetermined control unit.

<Embodiment 2> As shown in FIG. 3, the rotary joint for power transmission according to Embodiment 2 differs from Embodiment 1 in that the coil 18 of the rotating ferrite core unit 11 and the stationary side The coil 19 of the ferrite core unit 12 is configured such that their peripheral surfaces 18b, 19b face each other. That is, each coil 1
8 and 19 are wound into a large cylindrical shape and a small cylindrical shape, respectively, are fixed with a synthetic resin, and are nested so that their peripheral surfaces 18b and 19b face each other. It is fixed to the side ferrite core 16.

Third Embodiment As shown in FIG. 4, in the rotary joint for power transmission according to the third embodiment, as in the first embodiment, both ferrite cores 15 and 1 are connected.
6 and the annular space 17 are formed by a combination of two cylindrical cores 20a, 20b of different diameters surrounding the rotating shaft 10 doubly and two disk cores 21a, 21b of the same shape. The combination is different.

That is, the rotation side ferrite core 15
The disk-shaped core portion 21a is formed by a large-diameter cylindrical core portion 20a and a small-diameter cylindrical core portion 20b connected to the disk core portion 21a, and the stationary ferrite core 16 is formed only by the disk core portion 21b. In the rotation-side ferrite core 15, one end surface of the disk core portion 21a is fixed on the rotation support plate 13 with an adhesive or the like, and the other end surface of the disk core portion 21a has a large-diameter cylindrical core portion 20a and a small-diameter cylindrical core 20a. Part 20
One end surface of b is fixed to an adhesive or the like. In the stationary ferrite core 16, one end surface of the disk core portion 21b is fixed on the stationary support plate 14 with an adhesive or the like. Of course, the ferrite cores 15 and 16 may be switched between the stationary side and the rotating side. Further, the disk core portion 21a, the large-diameter cylindrical core portion 20a, and the small-diameter cylindrical core portion 20b of the rotating ferrite core 15 may be integrally formed from the beginning.

Small gaps 22a and 22b are formed between the ferrite cores 15 and 16 to allow rotation of the rotating body with respect to the stationary body. That is, gaps 22b, 22a are formed between the end surface C of the disk core portion 21b, which is the stationary ferrite core 16, and the end surfaces B, A of the large-diameter cylindrical core portion 20a and the small-diameter cylindrical core portion 20b of the rotating ferrite core 15.
Are opposed to each other. The end faces 22b and 22a facing each other via these gaps face each other without displacement, so that no leakage occurs in the magnetic flux on the magnetic flux path shown by the broken line. In order to obtain desired electromagnetic induction characteristics in power transmission, the size of the gaps 22b, 22a needs to be uniform over the entire circumference of the ferrite core, but the end faces A, B of the cylindrical core portions 20a, 20b or the disk Core part 21b
The purpose can be achieved by polishing the end face C of the first embodiment. Further, the end faces A of the core portions 20a, 20b, 21b,
To match B and C with each other, cylindrical core portions 20a and 20b
It is sufficient to cut or polish the end faces A, B, and C of the disk core portion 21b. Therefore, the yield of the ferrite cores 15 and 16 is improved.

The coil 18 of the rotating ferrite core unit 11 and the stationary ferrite core unit 12 are accommodated in an annular space 17 formed in the ferrite cores 15 and 16.
Coil 19 is housed. Both coils 18, 19
The rotating ferrite core 15 and the stationary ferrite core 16 are arranged such that their end faces 18a and 19a face each other.
Are fixed respectively.

<Fourth Embodiment> As shown in FIG. 5, in the rotary joint for power transmission according to the fourth embodiment, as in the first embodiment, both ferrite cores 15, 1 are connected.
6 and the annular space 17 are formed by a combination of two cylindrical cores 20a, 20b of different diameters surrounding the rotating shaft 10 doubly and two disk cores 21a, 21b of the same shape. The combination is different.

That is, the rotating ferrite core 15
Formed by a small-diameter cylindrical core portion 20b and two disk core portions 21a and 21b coupled to the small-diameter cylindrical core portion 20b;
The stationary ferrite core 16 is formed only of the large-diameter cylindrical core portion 20a. In the rotation-side ferrite core 15, one end surface of the disk core portion 21a is fixed on the rotation support plate 13 with an adhesive or the like, and one end surface of the small-diameter cylindrical core portion 20b is bonded to the other end surface of the disk core portion 21a. One end surface of another disk core portion 21b is fixed to the other end surface of the small-diameter cylindrical core portion 20b by an adhesive or the like. In the stationary ferrite core 16, one end surface of the large-diameter cylindrical core portion 20a is fixed on the stationary supporting plate 14 with an adhesive or the like. Of course, both ferrite cores 15,
16 may be switched between the stationary side and the rotating side. Further, the disk core portion 21a, the small-diameter cylindrical core portion 20b, and the disk core portion 21b of the rotation-side ferrite core 15 may be integrally formed from the beginning.

A small gap is formed between the ferrite cores 15 and 16 to allow the rotation of the rotating body with respect to the stationary body. That is, the inner peripheral surface E of the large-diameter cylindrical core portion 20a of the stationary ferrite core 16 and the outer peripheral surfaces F of the two disk core portions 21a and 21b of the rotating ferrite core 15
G are opposed to each other via gaps 22a and 22b. The peripheral surfaces E, F, and G facing each other via the gaps 22a and 22b face each other, and therefore, no leakage occurs in the magnetic flux on the magnetic flux path indicated by the broken line. In order to obtain desired electromagnetic induction characteristics in power transmission, the gaps 22a and 22
It is necessary to make the size of b uniform over the entire circumference of the ferrite cores 15 and 16, but by polishing the inner peripheral surface E of the cylindrical core portion 20a or the outer peripheral surfaces F and G of the disk core portions 21a and 21b. That goal can be achieved. In order to make the peripheral surfaces E, F, and G of the core portions 20a, 21a, and 21b face each other, the cylindrical core portion 20a and the disk core portions 21a, 21
It is sufficient to cut or polish the peripheral surfaces E, F, and G of 1b. Therefore, the yield of the ferrite cores 15 and 16 is improved.

The coil 18 of the rotating ferrite core unit 11 and the stationary ferrite core unit 12 are accommodated in an annular space 17 formed in the ferrite cores 15 and 16.
Coil 19 is housed. Both coils 18, 19
The rotating ferrite core 15 and the stationary ferrite core 16 are arranged such that their circumferential surfaces 18b and 19b face each other.
Are fixed respectively.

Fifth Embodiment As shown in FIG. 6, the rotary joint for power transmission according to the fifth embodiment differs from the fourth embodiment in that the rotary ferrite core 15
Is a large-diameter cylindrical core portion 20a and the large-diameter cylindrical core portion 20a.
The stationary ferrite core 16 is formed by two disk core portions 21a and 21b joined to the small-diameter cylindrical core portion 20b.
Only formed. In the rotation-side ferrite core 15, the outer peripheral surfaces of the disk cores 21a and 21b are fixed to the upper and lower ends of the inner peripheral surface of the large-diameter cylindrical core portion 20a by an adhesive or the like, respectively, so that the large-diameter cylindrical core portion 20a and the disk core portion 21a. ,
One end surface of 21b is fixed on the rotation support plate 13 with an adhesive or the like. In the stationary ferrite core 16,
One end surface of the small-diameter cylindrical core portion 20b is fixed on the stationary-side support plate 14 with an adhesive or the like. Of course, the ferrite cores 15 and 16 may be switched between the stationary side and the rotating side. Further, the large-diameter cylindrical core portion 20a and the disk cores 21a and 21b in the rotation-side ferrite core 15 may be integrally formed from the beginning.

Small gaps 22a and 22b are formed between the ferrite cores 15 and 16 to allow rotation of the rotating body with respect to the stationary body. That is, the outer peripheral surface H of the small-diameter cylindrical core portion 20b of the stationary ferrite core 16 and the two disk core portions 21a, 21 of the rotating ferrite core 15
b are opposed to the inner peripheral surfaces I and J via gaps 22a and 22b. The circumferential surfaces H, I, and J facing each other via these gaps 22a and 22b face each other, and therefore, no leakage occurs in the magnetic flux on the magnetic flux path indicated by the broken line. In order to obtain desired electromagnetic induction characteristics in power transmission, the size of the gap needs to be uniform over the entire circumference of the ferrite core, but the outer peripheral surface H of the small-diameter cylindrical core portion 20b or the disk core portions 21a, 21b. The purpose can be achieved by polishing the inner peripheral surfaces I and J of the above. The core 20
In order to make the peripheral surfaces H, I, J of b, 21a, 21b face each other, it is sufficient to cut or polish the peripheral surfaces H, I, J of the cylindrical core portion 20b and the disk core portions 21a, 21b. Therefore, the yield of the ferrite cores 15 and 16 is improved.

The coil 18 of the rotating ferrite core unit 11 and the stationary ferrite core unit 12 are accommodated in an annular space 17 formed in the ferrite cores 15 and 16.
Coil 19 is housed. Both coils 18, 19
The rotating ferrite core 15 and the stationary ferrite core 16 are arranged such that their circumferential surfaces 18b and 19b face each other.
Are fixed respectively.

Sixth Embodiment As shown in FIGS. 7 and 8, in the rotary joint for power transmission according to the sixth embodiment, the stationary ferrite core 16 of the first to fifth embodiments is held. The stationary support plate 14 is supported on the rotating shaft 10 via a ball bearing 28. Also,
Rotation support plate 13 holding rotation-side ferrite core 15
Is in contact with an inner peripheral surface of a cylindrical housing 29 provided so as to surround the rotating shaft 10 via a roller 30. The housing 29 is made of a non-magnetic material such as stainless steel, and holds the stationary ferrite core 16 and stops at a fixed position.

In addition, the rotating support plate 13 and the stationary support plate 14
, A transmission antenna 25, a reception antenna 26, and various electrical components are respectively attached. A signal connector 27 electrically connected to the receiving antenna 26 and a power connector 24 electrically connected to the stationary coil 19 are attached to the end plate 29 a of the housing 29.

According to the power transmission rotary joint, when the rotary shaft 10 rotates, the rotary support plate 13 rotates with respect to the stationary support plate 14. The rotation support plate 13 rotates with the rotation side ferrite core unit 11 and the transmission antenna 25, and the stationary support plate 14 stops at a fixed position while holding the stationary side ferrite core unit 12 and the reception antenna 26.

When a high-frequency pulse is applied to the coil 19 of the stationary ferrite core unit 12, the magnetic flux flows from the stationary ferrite core 16 to the rotating ferrite core 15, and a path for the magnetic flux is secured. Due to the electromagnetic induction effect of the magnetic flux, the coil 18 of the rotation side ferrite core unit 11
Current is generated.

As a result, power is supplied to, for example, various electrical components on the rotating side, and the electrical components become operable. In addition, various electrical components transmit various information output by a predetermined sensor on the rotation side from the transmission antenna 25. On the stationary side, the receiving antenna 26
Receives various information and sends it to a predetermined control unit.

[0047]

According to the present invention, a ferrite core for power transmission is constituted by a combination of two cylindrical cores of different diameters surrounding a rotating shaft and two disk cores of the same shape. Therefore, the end faces or the peripheral faces of the core portion can be properly and easily opposed to each other through a gap required for rotation of the rotating body with respect to the stationary body, so that leakage of magnetic flux is reduced and power transmission efficiency is reduced. Can be enhanced. In addition, the dimensional accuracy can be relaxed in the forming and firing steps of the ferrite core, and the processing such as cutting and polishing after the forming of the ferrite core can be reduced, and the yield of the ferrite core can be increased. In addition, the ferrite core can be made larger or have a larger hollow diameter, and large power transmission becomes possible.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing a power transmission rotary joint according to the present invention.

FIG. 2 is a vertical sectional view of a power transmission rotary joint according to the present invention.

FIG. 3 is a vertical sectional view showing a second embodiment of the present invention.

FIG. 4 is a vertical sectional view showing a third embodiment of the present invention.

FIG. 5 is a vertical sectional view showing a fourth embodiment of the present invention.

FIG. 6 is a vertical sectional view showing a fifth embodiment of the present invention.

FIG. 7 is a plan view of a power transmission rotary joint according to a sixth embodiment of the present invention.

8 is a half sectional view of the power transmission rotary joint shown in FIG. 7;

FIG. 9 is a vertical sectional view of a conventional power transmission rotary joint.

FIG. 10 is an exploded perspective view of a pot-type ferrite core of the power transmission rotary joint shown in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Rotation axis 11 ... Rotation side ferrite core unit 12 ... Stationary side ferrite core unit 13 ... Rotation support plate 14 ... Stationary support plate 15 ... Rotation side ferrite core 16 ... Stationary side ferrite core 17 ... Annular empty room 18 ... Rotation side coil 19: stationary side coil 18a, 19a: coil end surface 18b, 19b: coil peripheral surface 20a: large-diameter cylindrical core portion 20b ... small-diameter cylindrical core portion 21a, 21b: disk core portion 22a, 22b: gap for rotation A, B, C, D: End surface of core portion E, F, G, H, I, J: Peripheral surface of core portion

Claims (6)

[Claims] 1. A ferrite core unit comprising: a rotating ferrite core unit fixed to a rotating body including a rotating shaft; and a stationary ferrite core unit fixed to a stationary body stationary with respect to the rotating body. Are arranged so as to form an annular space between the two ferrite cores, and the coils of the two ferrite core units are housed in the annular space so as to face each other. In the rotary joint for power transmission, which is configured to generate an induced electromotive force on the core unit side, a combination of two different-diameter cylindrical core portions and two identical disk core portions surrounding the rotation axis doubly. The two ferrite cores and the annular cavity are formed, and are fixed to the predetermined core portion fixed to the rotating body and the stationary body. A rotary joint for power transmission, characterized in that a gap for rotation is formed between end surfaces with respect to a predetermined core portion or between peripheral surfaces. 2. The ferrite core according to claim 1, wherein the one ferrite core is formed of a disc core and a small-diameter cylindrical core connected to the disc core, and the other ferrite core is formed of a disc core and a large core connected to the disc core. Formed between the end surface of one disk core portion and the end surface of the small-diameter cylindrical core portion, and between the end surface of the other disk core portion and the end surface of the large-diameter cylindrical core portion, respectively. 2. A gap is formed.
The rotary joint for power transmission according to 1. 3. The ferrite core of claim 1, wherein the one ferrite core is formed of only a disc core, and the other ferrite core is formed of a disc core, and a large-diameter cylindrical core and a small-diameter cylindrical core connected to the disc core. 2. The gap according to claim 1, wherein the gap is formed between an end surface of the disk core portion as one ferrite core and each end surface of the large-diameter cylindrical core portion and the small-diameter cylindrical core portion of the other ferrite core. The rotary joint for power transmission described. 4. The ferrite core according to claim 1, wherein the one ferrite core is formed of only a large-diameter or small-diameter cylindrical core, and the other ferrite core is formed of a small-diameter or large-diameter cylindrical core and the small-diameter or large-diameter cylindrical core. The gap is formed between the peripheral surface of the large-diameter or small-diameter cylindrical core portion, which is one ferrite core, and each of the two disk core portions of the other ferrite core. The rotary joint for power transmission according to claim 1, characterized in that: 5. The coil of the rotating ferrite core unit and the coil of the stationary ferrite core unit are provided such that their end faces face each other. The rotary joint for power transmission according to any one of the above. 6. The coil of the rotating-side ferrite core unit and the coil of the stationary-side ferrite core unit are provided such that their peripheral surfaces face each other. The rotary joint for power transmission according to any one of the above.