JP2014233113A - Non-contact power transmission system and power receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission system capable of performing power transmission with high efficiency even under a long distance.SOLUTION: The non-contact power transmission system includes: a power transmission coil that generates an alternate magnetic flux; and a power receiving coil that is magnetically coupled with the power transmission coil to induce a current according to the alternate magnetic flux. The power receiving coil includes a cylindrical magnetic member; and a winding surrounding the magnetic member.

Description

  The present invention relates to a power transmission technique capable of performing power transmission in a contactless manner.

  Non-contact power transmission can be used for various devices. For example, the electric toothbrush may be charged by non-contact power transmission. As a result of the non-contact power transmission, the electronic components arranged in the housing of the electric toothbrush are appropriately isolated from water (see Patent Document 1).

  Patent Document 1 discloses an electric toothbrush and a charging device for charging the electric toothbrush. The charging device includes a primary coil that generates an alternating magnetic flux. The electric toothbrush includes a planar coil through which a current induced by an alternating magnetic flux flows. As a result of the current induced in the planar coil being output to the secondary battery, the electric toothbrush is appropriately charged.

JP 2012-29517 A

  The electric toothbrush of patent document 1 needs to be installed appropriately on a charging device. The power transmission principle disclosed in Patent Document 1 does not allow a long distance between the electric toothbrush and the charging device. If the electric toothbrush is separated from the charging device, charging to the electric toothbrush is not achieved.

  If the electric toothbrush can receive power transmission from the charging device while the electric toothbrush is separated from the charging device, the user can place the electric toothbrush in various places. Therefore, there is a demand for a power transmission system that can achieve high power transmission efficiency even when the electric toothbrush is separated from the charging device.

  High power transmission efficiency requires a coil having a high coupling coefficient between coils and a high Q value. A large coil is required to meet these requirements. However, the internal space defined by the housing of the electric toothbrush is finite. Therefore, a large housing is required to use a large coil. An excessively large housing is inconvenient for a user who uses an electric toothbrush. Or if a big coil is arrange | positioned in a housing | casing, inconvenience will arise in accommodation in the housing | casing of various components (for example, a secondary battery, a motor, and a circuit board) for operating an electric toothbrush. In addition, problems such as heat generation of the secondary battery or motor and malfunction of circuit components may occur due to the magnetic flux generated from the coil disposed in the housing.

  The above-mentioned problem is common not only to the electric toothbrush but also to other devices that use a non-contact power transmission system.

  An object of the present invention is to provide a non-contact power transmission technology that enables power transmission with high efficiency even in the presence of a long distance.

  A non-contact power transmission system according to one aspect of the present invention includes a power transmission coil unit that generates an alternating magnetic flux, and a power reception coil that is magnetically coupled to the power transmission coil unit and that induces a current corresponding to the alternating magnetic flux. A section. The power receiving coil portion includes a cylindrical magnetic body and a winding surrounding the magnetic body.

  According to the above configuration, since the power receiving coil portion includes the cylindrical magnetic body and the windings surrounding the magnetic body, high inductance is achieved. Therefore, even if a long distance exists between the power transmission coil unit and the power reception coil unit, very efficient power transmission is achieved.

  In the above-described configuration, the magnetic body includes a cylindrical portion that defines an internal space that houses an operation portion that performs a predetermined operation using electric power acquired by the current, and a first wall portion that at least partially closes the internal space. , May be included. The first wall portion may be disposed between the operating portion and the power transmission coil portion.

  According to the said structure, the 1st wall part arrange | positioned between an operation | movement part and a power transmission coil part can receive an alternating magnetic flux efficiently. Therefore, even if a long distance exists between the power transmission coil unit and the power reception coil unit, very efficient power transmission is achieved. In addition, since the first wall portion reduces the influence of the alternating magnetic flux on the operating portion, the operating portion is less likely to malfunction.

  The said structure WHEREIN: The said cylinder part may contain the 1st end part and the 2nd end part spaced apart from the said power transmission coil part rather than the said 1st end part. The first wall portion may at least partially close a first opening defined by the first end portion.

  According to the said structure, since a 1st wall part obstruct | occludes at least partially the 1st end part near a power transmission coil part rather than a 2nd end part, a 1st wall part receives an alternating magnetic flux efficiently. Can do. Therefore, even if a long distance exists between the power transmission coil unit and the power reception coil unit, very efficient power transmission is achieved.

  The said structure WHEREIN: The said 1st wall part may be formed so that isolation | separation from the said cylinder part is possible.

  According to the said structure, since a 1st wall part is formed so that isolation | separation from a cylinder part is possible, the assembly of an electric power transmission system becomes easy.

  In the above configuration, the power transmission system may further include a housing that houses the power receiving coil unit. The magnetic body may include a cylindrical portion that defines an internal space that houses an operation portion that performs a predetermined operation using electric power acquired by the current, and a second wall portion that at least partially closes the internal space. Good. The second wall portion may confine the operating portion in the internal space in cooperation with the casing.

  According to the above configuration, the second wall portion cooperates with the casing to confine the operating section in the internal space, so that the operating section is appropriately accommodated in the casing.

  The said structure WHEREIN: The said cylinder part may contain the 1st end part which opposes the said housing | casing, and the 2nd end part spaced apart from the said power transmission coil part rather than the said 1st end part. The second wall portion may at least partially close the second end portion.

  According to the above configuration, the first end portion faces the housing, and the second wall portion at least partially closes the second end portion that is further away from the power transmission coil portion than the first end portion. , The internal space becomes wider.

  The said structure WHEREIN: The said cylinder part may also contain the 1st cylinder part and the 2nd cylinder part arrange | positioned in alignment with the said 1st cylinder part.

  According to the above configuration, the cylindrical portion includes the first cylindrical portion and the second cylindrical portion that is arranged in alignment with the first cylindrical portion. Therefore, adjustment to the inductance of the cylindrical portion is facilitated.

  The said structure WHEREIN: The said 2nd cylinder part may be spaced apart and arrange | positioned from the said 1st cylinder part.

  According to the said structure, since a 2nd cylinder part is spaced apart and arrange | positioned from a 1st cylinder part, alternating current resistance becomes small. As a result of the small AC resistance, very efficient power transmission is achieved even if there is a long distance between the power transmission coil section and the power reception coil section.

  The said structure WHEREIN: The said receiving coil part may also contain the spacer which maintains the distance between a said 1st cylinder part and a said 2nd cylinder part.

  According to the above configuration, since the spacer maintains the distance between the first tube portion and the second tube portion, the variation in parameters that affect power transmission is reduced. Moreover, even if an impact is applied to the cylinder part from the outside, the cylinder part is not easily damaged.

  In the above configuration, the spacer may be a non-magnetic material.

  According to the said structure, since a spacer is a nonmagnetic material, alternating current resistance becomes small. As a result of the small AC resistance, very efficient power transmission is achieved even if there is a long distance between the power transmission coil section and the power reception coil section.

  In the above-described configuration, the power transmission system may further include a rectifying unit that rectifies the current flowing through the power receiving coil unit. The power may be acquired by the current that has passed through the rectifying unit.

  According to the above configuration, the operation unit performs a predetermined operation with the electric power acquired by the current that has passed through the rectification unit, so that the design of the operation unit is facilitated.

  In the above configuration, the power transmission system may further include a resonance circuit unit that is magnetically connected to the power receiving coil unit between the power transmitting coil unit and the power receiving coil unit. The resonant circuit unit may resonate according to the alternating magnetic flux and induce the current in the power receiving coil unit that is electrically independent from the resonant circuit unit.

  According to the above configuration, the resonance unit resonates according to the alternating magnetic flux and induces a current in the power receiving coil unit. Therefore, even if a long distance exists between the power transmitting coil unit and the power receiving coil unit, it is very efficient. Power transmission is achieved.

  A power receiving device according to another aspect of the present invention includes a cylindrical magnetic body, a winding through which the current flows, and an operation unit that performs a predetermined operation using electric power acquired by the current. The magnetic body includes a cylinder portion that houses the operating portion. The winding surrounds the cylindrical portion.

  According to the said structure, since an operation | movement part is arrange | positioned at a cylinder part, a power receiving apparatus is designed small. Since the winding surrounds the cylindrical portion, the power used by the operating portion is efficiently generated.

  The power transmission technique according to the present invention can achieve highly efficient power transmission even in the presence of a long distance.

It is a schematic block diagram showing the function structure of the non-contact-type electric power transmission system according to 1st Embodiment. It is a schematic plan view of the power transmission coil part of the electric power transmission system shown by FIG. It is a schematic side view of the power transmission coil unit shown in FIG. 2A. It is a schematic perspective view of the receiving coil part of the electric power transmission system shown by FIG. It is a schematic bottom view of the receiving coil part shown by FIG. 3A. It is a schematic perspective view of the magnetic cylinder of the electric power transmission system shown by FIG. FIG. 4B is a schematic bottom view of the magnetic cylinder shown in FIG. 4A. It is a schematic block diagram showing the function structure of the non-contact-type electric power transmission system according to 2nd Embodiment. FIG. 6 is a schematic plan view of a power transmission coil unit of the power transmission system illustrated in FIG. 5. It is a schematic side view of the power transmission coil unit shown in FIG. 6A. It is a schematic perspective view of the receiving coil part of the electric power transmission system shown by FIG. It is a schematic bottom view of the receiving coil part shown by FIG. 7A. FIG. 6 is a schematic perspective view of a magnetic cylinder of the power transmission system shown in FIG. 5. FIG. 8B is a schematic bottom view of the magnetic cylinder shown in FIG. 8A. It is a schematic circuit diagram of the power transmission apparatus of 3rd Embodiment. It is a schematic perspective view of the power transmission coil part of the power transmission apparatus shown by FIG. It is a schematic circuit diagram of the power receiving apparatus of 3rd Embodiment. It is a schematic circuit diagram of the power receiving apparatus of 4th Embodiment. It is a schematic perspective view of the toothbrush of 5th Embodiment. FIG. 14 is a schematic partial cross-sectional view of the toothbrush shown in FIG. 13. It is a schematic perspective view of the toothbrush of 6th Embodiment. It is a schematic perspective view of the toothbrush of 7th Embodiment. FIG. 17 is a schematic exploded view of the toothbrush shown in FIG. 16. It is a schematic fragmentary sectional view of the toothbrush of 8th Embodiment. It is a schematic fragmentary sectional view of the toothbrush of 9th Embodiment. It is a schematic fragmentary sectional view of the toothbrush of 10th Embodiment. It is a schematic fragmentary sectional view of the toothbrush of 11th Embodiment. It is an expanded sectional view of the toothbrush shown by FIG. It is schematic sectional drawing of the toothbrush shown by FIG. It is a schematic circuit diagram of the power receiving apparatus of 12th Embodiment. It is the schematic showing the positional relationship between a power transmission coil part, a resonance circuit part, and a receiving coil part. It is a schematic circuit diagram of the power receiving apparatus of 13th Embodiment. It is a schematic fragmentary sectional view of the toothbrush of 14th Embodiment.

  Hereinafter, an exemplary contactless power transmission system will be described with reference to the drawings. It should be noted that terms used in the following description, such as “up”, “down”, “left”, and “right”, are merely for the purpose of clarifying the description. Therefore, these terms do not limit the principle of the power transmission system at all.

<First Embodiment>
FIG. 1 is a schematic block diagram showing a functional configuration of a contactless power transmission system 100 according to the first embodiment. A power transmission system 100 will be described with reference to FIG. In FIG. 1, the solid line arrows represent the transmission of electrical energy. Dotted arrows conceptually represent magnetic flux.

  The power transmission system 100 includes a power transmission device 200 and a power reception device 300. The power transmission device 200 receives power from the power source ES. Thereafter, the power transmission device 200 generates alternating magnetic flux using electric power. The alternating magnetic flux generates an induced current in the power receiving device 300. The power receiving device 300 can perform a predetermined operation using the electric power acquired by the induced current corresponding to the alternating magnetic flux.

  The power transmission device 200 includes an input unit 210 and a power transmission coil unit 220. Electric power is input from the power source ES to the input unit 210. Thereafter, the electric power is transmitted from the input unit 210 to the power transmission coil unit 220. The power transmission coil unit 220 generates an alternating magnetic flux according to the supply of electric power.

  The power receiving device 300 includes a power receiving coil unit 310 and an operation unit 320. The power receiving coil unit 310 is magnetically connected to the power transmitting coil unit 220. Therefore, the power reception coil unit 310 generates an induced current in the presence of the magnetic field generated from the power transmission coil unit 220. The operation unit 320 can execute a predetermined operation using the power acquired by the induced current. The operation unit 320 may perform a dynamic operation (for example, displacement or vibration of an object) that accompanies the displacement of the object. Alternatively, the operation unit 320 may perform a static operation (for example, power storage) that does not involve displacement of an object. The principle of this embodiment is not limited at all by the operation of the operation unit 320.

  FIG. 2A is a schematic plan view of the power transmission coil unit 220. FIG. 2B is a schematic side view of the power transmission coil unit 220. With reference to FIG. 1 thru | or FIG. 2B, the power transmission coil part 220 is demonstrated.

  The power transmission coil unit 220 includes a magnetic plate 221 made of a magnetic material, and a winding 222 wound on the magnetic plate 221 in a substantially annular shape. The power transmission coil unit 220 substantially functions as a planar coil.

  The electric power is transmitted to the winding 222 through the input unit 210. Since the current flows through the winding 222 wound in a substantially annular shape on the magnetic plate 221, the power transmission coil unit 220 can generate a strong magnetic field.

  FIG. 3A is a schematic perspective view of the power receiving coil unit 310. FIG. 3B is a schematic bottom view of the power receiving coil unit 310. With reference to FIG. 1, FIG. 3A and FIG. 3B, the receiving coil part 310 is demonstrated.

  The power receiving coil unit 310 includes a substantially cylindrical magnetic tube 330 made of a magnetic material, and a winding 311 wound around the peripheral surface of the magnetic tube 330 in a spiral shape. The winding 311 includes a first end 312 electrically connected to the operating unit 320 and a second end 313 opposite to the first end 312. The first end 312 and the second end 313 may be connected to a circuit board (not shown) used as the operation unit 320. In the present embodiment, the magnetic cylinder 330 is exemplified as a cylindrical magnetic body.

  The winding 311 is wound around the magnetic cylinder 330. As a result, a high induced current flows through the winding 311 even if the magnetic field to which the power receiving coil unit 310 is exposed is weak. Therefore, the power reception coil unit 310 may be separated from the power transmission coil unit 220.

  FIG. 4A is a schematic perspective view of the magnetic cylinder 330. FIG. 4B is a schematic bottom view of the magnetic cylinder 330. The magnetic cylinder 330 will be described with reference to FIGS. 1, 4A and 4B.

  The substantially cylindrical magnetic cylinder 330 defines a substantially cylindrical internal space IS. The operation unit 320 may be accommodated in the internal space IS.

  In the present embodiment, the magnetic cylinder 330 exemplified as a magnetic body has a substantially cylindrical shape. Alternatively, the magnetic body may have other shapes. For example, the magnetic body may be an elliptical cylinder, or another cylindrical member having a peripheral surface formed by a curved surface. The shape and size of the magnetic body may be appropriately determined according to the shape and size of the power transmission coil unit.

Second Embodiment
In the first embodiment, a substantially cylindrical magnetic cylinder is exemplified as the magnetic body. Alternatively, the magnetic body may be a square tube. In the present embodiment, a power transmission system using a rectangular cylindrical magnetic material will be described.

  FIG. 5 is a schematic block diagram showing a functional configuration of a contactless power transmission system 100A according to the second embodiment. The power transmission system 100A will be described with reference to FIG. In FIG. 5, a solid line arrow represents transmission of electric energy. Dotted arrows conceptually represent magnetic flux. The same code | symbol is attached | subjected with respect to the element same as 1st Embodiment. The description related to the first embodiment is applied to elements having the same reference numerals.

  The power transmission system 100A includes a power transmission device 200A and a power reception device 300A. The power transmission device 200A receives power from the power source ES. Thereafter, power transmission device 200A generates magnetic flux using electric power. The magnetic flux generates an induced current in the power receiving device 300A. The power receiving device 300A can perform a predetermined operation using the electric power acquired by the induced current.

  Similarly to the first embodiment, the power transmission device 200 </ b> A includes an input unit 210. The power transmission device 200A further includes a power transmission coil unit 220A. Electric power is input from the power source ES to the input unit 210. Thereafter, the electric power is transmitted from the input unit 210 to the power transmission coil unit 220A. The power transmission coil unit 220A generates a magnetic field according to the supply of electric power.

  Similar to the first embodiment, the power receiving device 300 </ b> A includes an operation unit 320. The power receiving device 300A further includes a power receiving coil unit 310A. The power reception coil unit 310A is magnetically connected to the power transmission coil unit 220A. Therefore, the power receiving coil unit 310A generates an induced current in the presence of the magnetic field generated from the power transmitting coil unit 220A. The operation unit 320 can execute a predetermined operation using the power acquired by the induced current. The operation unit 320 may perform a dynamic operation (for example, displacement or vibration of an object) that accompanies the displacement of the object. Alternatively, the operation unit 320 may perform a static operation (for example, power storage) that does not involve displacement of an object. The principle of this embodiment is not limited at all by the operation of the operation unit 320.

  FIG. 6A is a schematic plan view of power transmission coil unit 220A. FIG. 6B is a schematic side view of power transmission coil unit 220A. With reference to FIG. 5 thru | or FIG. 6B, 220 A of power transmission coil parts are demonstrated.

  Similar to the first embodiment, the power transmission coil unit 220A includes a magnetic plate 221 formed of a magnetic material. The power transmission coil unit 220 </ b> A further includes a winding 222 </ b> A disposed on the magnetic plate 221. Unlike the first embodiment, the winding 222A draws a rectangular ring. The power transmission coil unit 220A substantially functions as a planar coil.

  The electric power is transmitted to the winding 222 </ b> A through the input unit 210. Since the current flows through the winding 222A wound in a substantially square ring shape on the magnetic plate 221, the power transmission coil unit 220A can generate a strong magnetic field.

  FIG. 7A is a schematic perspective view of power receiving coil section 310A. FIG. 7B is a schematic bottom view of the power receiving coil section 310A. The power receiving coil section 310A will be described with reference to FIGS. 5, 7A and 7B.

  Similarly to the first embodiment, the power receiving coil unit 310 </ b> A includes a winding 311. The power receiving coil portion 310A further includes a magnetic cylinder 330A formed of a magnetic material. The magnetic cylinder 330A is a square cylinder. The winding 311 is spirally wound around the peripheral surface of the magnetic cylinder 330A. As a result, even if the magnetic field to which the power receiving coil unit 310A is exposed is weak, a high induced current is generated in the power receiving coil unit 310A. Therefore, the power receiving coil unit 310A may be separated from the power transmitting coil unit 220A. In the present embodiment, the magnetic cylinder 330A is exemplified as a cylindrical magnetic body.

  FIG. 8A is a schematic perspective view of the magnetic cylinder 330A. FIG. 8B is a schematic bottom view of the magnetic cylinder 330A. The magnetic cylinder 330A will be described with reference to FIGS. 5, 8A, and 8B.

  The substantially rectangular cylindrical magnetic cylinder 330A defines an internal space ISA having a substantially quadrangular prism shape. The operation unit 320 may be accommodated in the internal space ISA.

  In the present embodiment, the magnetic cylinder 330A exemplified as a magnetic body is a square cylinder. Alternatively, the magnetic body may have other shapes. For example, the magnetic body may be a triangular cylinder or another polygonal cylinder. The shape and size of the magnetic body may be appropriately determined according to the shape and size of the power transmission coil unit.

  In the present embodiment, the shape of the magnetic cylinder 330A matches the shape of the power transmission coil unit 220A. In this case, if the magnetic cylinder 330A is brought close to the power transmission coil unit 220A, a current is efficiently induced in the power reception coil unit 310A. However, the magnetic cylinder does not have to conform to the shape of the power transmission coil unit. For example, the magnetic cylinder 330A may be exposed to the magnetic field created by the power transmission coil unit 220 described in the context of the first embodiment.

<Third Embodiment>
In the present embodiment, a circuit designed based on the principle of the first embodiment will be described. Note that the circuits described in the present embodiment are illustrative. Thus, other circuits designed based on known electrical technology may be used.

  FIG. 9 is a schematic circuit diagram of the power transmission device 200. The power transmission device 200 will be described with reference to FIG.

  The input unit 210 includes a full bridge circuit 211, a control IC 212, and a resonant capacitor 213. The full bridge circuit 211 includes four field effect transistors (shown using the symbols “FET1”, “FET2”, “FET3”, and “FET4” in FIG. 9). In the present embodiment, the full bridge circuit 211 receives a voltage of 18V. The control IC 212 alternately turns on and off a pair consisting of FET1 and FET4 and a pair consisting of FET2 and FET3. The resonant capacitor 213 cooperates with the winding 222 to form a resonant circuit. As a result of the on / off control by the control IC 212, a high frequency alternating current flows through the resonant capacitor 213 and the winding 222. In the present embodiment, the frequency of the alternating current is 400 kHz. The number of turns of the winding 222 is 10 turns. These design numerical values do not limit the principle of this embodiment at all.

  FIG. 10 is a schematic perspective view of the power transmission coil unit 220 disposed to face the power reception coil unit 310. The power transmission device 200 is further described with reference to FIGS. 1, 9, and 10.

  The magnetic plate 221 includes an upper surface 223. The winding 222 is formed on the upper surface 223. The magnetic plate 221 may be an amorphous magnetic sheet.

  The alternating current flowing through the winding 222 creates a magnetic field that extends around the top surface 223. The magnetic field induces a current in the winding 311 of the power receiving coil unit 310. The electric power acquired by the induction of current is used for the operation of the operation unit 320.

  The capacitance “C” of the resonant capacitor 213 may be determined based on the following mathematical formula.

  The parameter “f” in the above formula is the frequency of the alternating current flowing through the winding 222. The parameter “L” in the above equation is an inductance determined by the characteristics of the magnetic plate 221 and the characteristics of the winding 222.

  The magnetic cylinder 330 is made of ferrite. The outer diameter of the magnetic cylinder 330 is “φ20 mm”. The inner diameter of the magnetic cylinder 330 is “φ18 mm”. The length of the magnetic cylinder 330 is “135 mm”. The winding 311 has 130 turns. These design numerical values do not limit the principle of this embodiment at all.

  FIG. 11 is a schematic circuit diagram of the power receiving device 300. The power receiving apparatus 300 is described with reference to FIGS. 1 and 9 to 11.

  As described with reference to FIG. 1, the power reception device 300 includes a power reception coil unit 310 and an operation unit 320. FIG. 11 shows a motor 321 used as the operation unit 320.

  The power receiving device 300 may include a conversion circuit 340 that converts an alternating current flowing through the winding 311 into a direct current. The conversion circuit 340 includes a resonance capacitor 341, a rectification bridge circuit 342, and a smoothing capacitor 343. The resonance capacitor 341 forms a resonance circuit in cooperation with the winding 311. The resonance frequency of the resonance circuit (resonance capacitor 341, winding 311 and magnetic cylinder 330) in the power receiving device 300 matches the resonance frequency of the resonance circuit (resonance capacitor 213, winding 222 and magnetic plate 221) in the power transmission device 200. Thus, the capacitance of the resonant capacitor 341 is set.

  The rectifier bridge circuit 342 includes four diodes (represented by symbols “D1”, “D2”, “D3”, and “D4” in FIG. 11). The rectifying bridge circuit 342 rectifies the alternating current induced in the power receiving coil unit 310. In the present embodiment, the rectification bridge circuit 342 is exemplified as a rectification unit.

  The smoothing capacitor 343 stores electric charge from the current rectified by the rectifying bridge circuit 342. The smoothing capacitor 343 outputs the electric charge as a direct current to the motor 321. As a result, the motor 321 is driven.

<Fourth embodiment>
In the third embodiment, the motor used as the operating unit directly receives the direct current generated by the conversion circuit. Alternatively, the operating unit may have a power storage function. The motor may operate using the stored power. In the present embodiment, a power receiving device including an operation unit having a power storage function is described.

  FIG. 12 is a schematic circuit diagram of the power receiving device 300B. With reference to FIG. 12, power receiving device 300B is described. The same code | symbol is attached | subjected with respect to the element same as 3rd Embodiment. The description related to the third embodiment is applied to elements having the same reference numerals.

  Similarly to the third embodiment, the power receiving device 300B includes a power receiving coil unit 310 and a conversion circuit 340. The power receiving device 300B further includes an operation unit 320B.

  Similar to the third embodiment, the operation unit 320 </ b> B includes a motor 321. The operation unit 320B further includes a secondary battery 322 electrically connected between the motor 321 and the smoothing capacitor 343. The direct current is output from the smoothing capacitor 343 to the secondary battery 322. As a result, the secondary battery 322 can store electricity. The motor 321 can operate by consuming electric power stored in the secondary battery 322.

<Fifth Embodiment>
In the present embodiment, an electric toothbrush constructed based on the principle described in relation to the fourth embodiment will be described. In the present embodiment, the electric toothbrush functions as a power receiving device.

  FIG. 13 is a schematic perspective view of an electric toothbrush (hereinafter referred to as “toothbrush 400”) of the fifth embodiment. The toothbrush 400 is demonstrated with reference to FIG.12 and FIG.13. The same code | symbol is attached | subjected with respect to the element same as 4th Embodiment. The description related to the fourth embodiment is applied to elements having the same reference numerals.

  The toothbrush 400 includes a lower housing 401, an upper housing 402, and a brush unit 403. The upper housing 402 is thinner than the lower housing 401. The user can hold the lower casing 401 and insert the upper casing 402 into the oral cavity. As a result, the brush part 403 is brought into contact with the user's teeth.

  The winding 311, the motor 321, the magnetic cylinder 330, the secondary battery 322, and the conversion circuit 340 are mainly accommodated in the lower housing 401. A transmission mechanism (not shown) for transmitting from the motor 321 to the brush unit 403 is accommodated in the upper housing 402. As a result of the transmission of the driving force from the motor 321 to the brush unit 403, the brush unit 403 can operate to clean the teeth. In the present embodiment, the lower housing 401 is exemplified as the housing.

  FIG. 14 is a schematic partial cross-sectional view of the toothbrush 400. The toothbrush 400 is further described with reference to FIGS. 12 and 14.

  The lower housing 401 includes a cylindrical peripheral wall 411 and a bottom wall 412 connected to the lower end of the peripheral wall 411. The peripheral wall 411 defines an accommodation space for accommodating the winding 311, the motor 321, the magnetic cylinder 330, the secondary battery 322, and the conversion circuit 340 between the bottom wall 412 and the upper housing 402.

  The magnetic cylinder 330 is inserted into the accommodation space. The winding 311 is disposed between the peripheral wall 411 and the magnetic cylinder 330.

  As described in relation to the first embodiment, the magnetic cylinder 330 forms the internal space IS. The circuit board 350 on which the motor 321, the secondary battery 322, and the conversion circuit 340 are constructed is disposed in the internal space IS. Since the motor 321, the secondary battery 322, and the circuit board 350 are arranged in the magnetic cylinder 330, the design of the lower housing 401 does not become excessively large. In addition, since the magnetic cylinder 330 surrounds the motor 321, the secondary battery 322, and the circuit board 350, the magnetic flux generated due to the alternating current flowing through the winding 311 is generated by the motor 321, the secondary battery 322, and the circuit board 350. It is hard to affect. Therefore, unintended heating and malfunction of the motor 321, the secondary battery 322, and the circuit board 350 are less likely to occur.

<Sixth Embodiment>
The magnetic cylinder may be designed to confine the operating part in the internal space. In the present embodiment, an electric toothbrush provided with a magnetic body capable of confining a motor and a secondary battery in an internal space will be described.

  FIG. 15 is a schematic partial cross-sectional view of the toothbrush 400C. The toothbrush 400C will be further described with reference to FIG. The same code | symbol is attached | subjected with respect to the element same as 5th Embodiment. The description related to the fifth embodiment is applied to elements having the same reference numerals.

  As in the fifth embodiment, the toothbrush 400C includes a lower housing 401, an upper housing 402, a brush unit 403, a winding 311, a motor 321, a secondary battery 322, and a circuit board 350. Prepare. The toothbrush 400C further includes a magnetic cylinder 330C. The magnetic cylinder 330 </ b> C includes a cylinder portion 331 that defines an internal space IS that accommodates the motor 321, the secondary battery 322, and the circuit board 350. The cylindrical portion 331 includes a lower end portion 332 that faces the bottom wall 412 of the lower housing 401, and an upper end portion 333 that is opposite to the lower end portion 332. The magnetic cylinder 330C includes an upper piece 334 that partially closes the upper opening defined by the upper end 333. The motor 321 includes a shaft 323 that protrudes upward beyond the upper piece 334. The shaft 323 is connected to a transmission mechanism (not shown) for transmitting from the motor 321 to the brush unit 403. In the present embodiment, the lower end 332 is exemplified as the first end. The upper piece 334 is exemplified as the second wall portion.

  As shown in FIG. 15, the toothbrush 400 </ b> C is typically arranged so that the bottom wall 412 faces the power transmission coil unit 220. As a result, the upper end 333 is farther from the power transmission coil unit 220 than the lower end 332. In the present embodiment, the upper end portion 333 is exemplified as the second end portion.

  The motor 321, the secondary battery 322, and the circuit board 350 are supported by the bottom wall 412. The upper piece 334 partially closes the upper opening defined by the upper end 333. Therefore, the upper piece 334 can confine the motor 321, the secondary battery 322, and the circuit board 350 in the internal space IS in cooperation with the bottom wall 412. In the present embodiment, the upper opening is exemplified as the second opening.

  In the present embodiment, the upper piece 334 exemplified as the second wall portion partially closes the upper opening. Alternatively, the second wall portion may completely close the opening defined by the cylindrical portion. The shape of the second wall portion may be appropriately determined based on the design of the power receiving device.

<Seventh embodiment>
The magnetic cylinder is preferably designed so as to effectively receive the alternating magnetic flux from the power transmission coil section. In the present embodiment, an electric toothbrush including a magnetic cylinder that can effectively receive an alternating magnetic flux is described.

  FIG. 16 is a schematic partial cross-sectional view of the toothbrush 400D. The toothbrush 400D will be further described with reference to FIG. The same code | symbol is attached | subjected with respect to the element same as 6th Embodiment. The description related to the sixth embodiment is applied to elements having the same reference numerals.

  As in the sixth embodiment, the toothbrush 400D includes a lower housing 401, an upper housing 402, a brush unit 403, a winding 311, a motor 321, a secondary battery 322, and a circuit board 350. Prepare. The toothbrush 400D further includes a magnetic cylinder 330D.

  Similar to the sixth embodiment, the magnetic cylinder 330 </ b> D includes a cylinder part 331 and an upper piece 334. The magnetic cylinder 330 </ b> D further includes a lower piece 335 that closes the lower opening defined by the lower end 332 of the cylinder 331. Unlike the upper piece 334 that partially closes the upper end 333, the lower piece 335 closes the lower end 332 closer to the power transmission coil unit 220 than the upper end 333. Therefore, the lower piece 335 is disposed between the power transmission coil unit 220 and the secondary battery 322. As a result, the lower piece 335 is effectively exposed to the alternating magnetic flux generated from the power transmission coil unit 220. In addition, since the lower piece 335 exists, the alternating magnetic flux generated from the power transmission coil unit 220 is less likely to affect the motor 321, the secondary battery 322, and the circuit board 350. In the present embodiment, the lower piece 335 is exemplified as the first wall portion. The lower opening is exemplified as the first opening.

  In the present embodiment, the lower piece 335 exemplified as the first wall portion closes the lower end portion 332. Alternatively, the first wall portion may partition an internal space defined by the tube portion between the lower end portion and the upper end portion.

  FIG. 17 is a schematic exploded view of the toothbrush 400D. The toothbrush 400D will be further described with reference to FIG.

  The lower piece 335 is separable from the cylindrical portion 331 while being fixed to the bottom wall 412. The bottom wall 412 includes an attachment plate 413 to which the lower piece 335 is attached, and a cylindrical male screw portion 414 protruding from the attachment plate 413 toward the peripheral wall 411. The peripheral wall 411 includes a lower end portion 416 in which a female screw portion 415 is formed. The male screw portion 414 is screwed to the female screw portion 415.

  The user can separate the bottom wall 412 from the peripheral wall 411. As a result, the lower opening 336 of the cylindrical portion 331 is opened. The user can insert the motor 321, the secondary battery 322, and the circuit board 350 into the internal space IS through the lower opening 336.

  In the present embodiment, the lower piece 335 exemplified as the first wall portion can be separated from the cylindrical portion 331. Alternatively, the first wall portion may be formed integrally with the tube portion.

<Eighth Embodiment>
In the seventh embodiment, the lower piece completely closes the lower opening. Alternatively, the lower piece may partially occlude the lower opening. If the lower opening is partially occluded by the lower piece, the winding is electrically connected to the circuit board through the lower piece.

  FIG. 18 is a schematic partial cross-sectional view of the toothbrush 400E. With reference to FIG. 18, the toothbrush 400E is further demonstrated. The same code | symbol is attached | subjected with respect to the element same as 7th Embodiment. The description related to the seventh embodiment is applied to elements having the same reference numerals.

  Similar to the seventh embodiment, the toothbrush 400 </ b> E includes an upper housing 402, a brush unit 403, a winding 311, a motor 321, a secondary battery 322, and a circuit board 350. The toothbrush 400E further includes a lower housing 401E and a magnetic cylinder 330E.

  Similarly to the seventh embodiment, the lower housing 401E includes a peripheral wall 411. Lower housing 401E further includes a bottom wall 412E. Similarly to the seventh embodiment, the bottom wall 412E includes a male screw portion 414 that is screwed into the peripheral wall 411. The bottom wall 412E further includes a mounting plate 413E. The male screw portion 414 protrudes from the mounting plate 413E. Unlike the seventh embodiment, a concave portion 417 is formed in the mounting plate 413E.

  Similar to the seventh embodiment, the magnetic cylinder 330 </ b> E includes a cylinder part 331 and an upper piece 334. The magnetic cylinder 330E further includes a lower piece 335E that partially closes the lower opening defined by the lower end 332 of the cylinder 331. Since the lower piece 335E does not completely close the lower opening, the recess 417 communicates with the internal space IS.

  The motor 321, the secondary battery 322, and the circuit board 350 are disposed in the magnetic cylinder 330E, while the winding 311 is disposed outside the magnetic cylinder 330E. Since the recess 417 communicates with the internal space IS, the wiring from the winding 311 to the circuit board 350 is appropriately formed through the recess 417.

<Ninth Embodiment>
The tube portion may be formed from a plurality of members. If the cylindrical portion is formed of a plurality of members, the power transmission efficiency is improved. In this embodiment, an electric toothbrush provided with the cylinder part formed from the several member is demonstrated.

  FIG. 19 is a schematic partial cross-sectional view of the toothbrush 400F. The toothbrush 400F will be further described with reference to FIG. The same code | symbol is attached | subjected with respect to the element same as 7th Embodiment. The description related to the seventh embodiment is applied to elements having the same reference numerals.

  Similar to the seventh embodiment, the toothbrush 400F includes a lower housing 401, an upper housing 402, a brush unit 403, a winding 311, a motor 321, a secondary battery 322, and a circuit board 350. Prepare. The toothbrush 400F further includes a magnetic cylinder 330F.

  Similar to the seventh embodiment, the magnetic cylinder 330 </ b> F includes an upper piece 334 and a lower piece 335. The magnetic cylinder 330F further includes a cylinder part 331F. The cylinder portion 331F includes an upper cylinder piece 337 to which the upper piece 334 is attached, a lower cylinder piece 338 that is closed by the lower piece 335, and an intermediate cylinder piece that is disposed between the upper cylinder piece 337 and the lower cylinder piece 338 339. The upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339 are aligned along the axis of the lower housing 401. In the present embodiment, one of the upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339 is exemplified as the first cylinder portion. Another one of the upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339 is exemplified as the second cylinder portion.

  The Q value representing the power transmission efficiency is expressed by the following mathematical formula.

  The parameter “Q” in the above formula is a Q value. The parameter “f” in the above equation is given by the above equation 1. The parameter “L” in the above formula is an inductance. The inductance changes depending on the arrangement and design of the upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339. The parameter “r” in the above formula is the AC resistance. The AC resistance varies depending on the arrangement and design of the upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339.

  In the present embodiment, the upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339 are each designed to have a length of “45 mm”. Each of the upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339 is a ferrite cylinder having an outer diameter of “20 mm” and an inner diameter of “18 mm”.

  The following table shows changes in the Q value according to the arrangement of the upper cylinder piece 337, the lower cylinder piece 338, and the middle cylinder piece 339.

  As a result of the gap being formed between the upper cylinder piece 337, the middle cylinder piece 339, and the lower cylinder piece 338 (condition 1), the inductance is reduced while the AC resistance is reduced as compared with the condition 2 in which no gap is formed. . In the above formula, the influence on the Q value of the decrease in the AC resistance value that functions as a denominator is larger than the influence of the inductance value that acts as a numerator. Therefore, Condition 1 can provide a larger Q value than Condition 2.

<Tenth Embodiment>
As described in relation to the ninth embodiment, the Q value varies depending on the gaps between the upper cylinder piece, the middle cylinder piece, and the lower cylinder piece. Therefore, it is preferable that the space | gap dimension between an upper cylinder piece, a middle cylinder piece, and a lower cylinder piece is maintained appropriately. In the present embodiment, a technique for maintaining the gap size between the upper cylinder piece, the middle cylinder piece, and the lower cylinder piece will be described.

  FIG. 20 is a schematic partial cross-sectional view of the toothbrush 400G. With reference to FIG. 20, toothbrush 400G is further demonstrated. The same code | symbol is attached | subjected with respect to the element same as 9th Embodiment. The description related to the ninth embodiment is applied to elements having the same reference numerals.

  Similar to the ninth embodiment, the toothbrush 400G includes a lower housing 401, an upper housing 402, a brush portion 403, a magnetic cylinder 330F, a winding 311, a motor 321, a secondary battery 322, a circuit, and the like. A substrate 350. The toothbrush 400G further includes an upper joint portion 351 that joins the upper cylinder piece 337 and the middle cylinder piece 339, and a lower joint portion 352 that joins the lower cylinder piece 338 and the middle cylinder piece 339. The upper joint portion 351 maintains a gap between the upper cylinder piece 337 and the middle cylinder piece 339. The lower joint portion 352 maintains a gap between the lower cylinder piece 338 and the middle cylinder piece 339. The upper joint portion 351 and the lower joint portion 352 are formed from a nonmagnetic material. As a result, a high Q value is achieved according to the principle of the ninth embodiment. In addition, while an external force is applied to the toothbrush 400G, a collision between the upper cylinder piece 337 and the middle cylinder piece 339 and a collision between the lower cylinder piece 338 and the middle cylinder piece 339 are less likely to occur. Therefore, the mechanical strength of the toothbrush 400G is increased. The upper joint portion 351 and the lower joint portion 352 may be formed from ABS resin. In the present embodiment, the upper joint portion 351 and the lower joint portion 352 are exemplified as spacers.

<Eleventh embodiment>
The upper cylinder piece, the middle cylinder piece, and the lower cylinder piece may be fixed by other techniques. In this embodiment, another technique for fixing the upper cylinder piece, the middle cylinder piece, and the lower cylinder piece will be described.

  FIG. 21 is a schematic partial cross-sectional view of the toothbrush 400H. The toothbrush 400H will be further described with reference to FIG. The same code | symbol is attached | subjected with respect to the element same as 9th Embodiment. The description related to the ninth embodiment is applied to elements having the same reference numerals.

  Similar to the ninth embodiment, the toothbrush 400H includes a lower housing 401, an upper housing 402, a brush unit 403, a winding 311, a motor 321, a secondary battery 322, and a circuit board 350. Prepare. The toothbrush 400H includes a magnetic cylinder 330H and a bobbin 360.

  Similar to the ninth embodiment, the magnetic cylinder 330 </ b> H includes an upper piece 334 and a lower piece 335. The magnetic cylinder 330H further includes an upper cylinder piece 337H partially closed by the upper piece 334 and a lower cylinder piece 338H closed by the lower piece 335. The upper cylinder piece 337H and the lower cylinder piece 338H are aligned in the lower housing 401. The bobbin 360 is disposed between the upper cylinder piece 337H / lower cylinder piece 338H and the winding 311.

  FIG. 22 is an enlarged cross-sectional view of the toothbrush 400H between the upper cylinder piece 337H and the lower cylinder piece 338H. With reference to FIG.21 and FIG.22, the toothbrush 400H is demonstrated.

  The bobbin 360 is a cylindrical body complementary to the upper cylindrical piece 337H and the lower cylindrical piece 338H. The winding 311 is wound around the outer peripheral surface of the bobbin 360.

  FIG. 23 is a schematic cross-sectional view of the toothbrush 400H. In FIG. 23, the upper cylinder piece 337H and the lower cylinder piece 338H are removed from the toothbrush 400H. The toothbrush 400H will be described with reference to FIGS.

  The bobbin 360 includes a projecting ring 361 that protrudes from the inner peripheral surface opposite to the outer peripheral surface around which the winding 311 is wound. The projecting ring 361 is inserted between the upper cylinder piece 337H and the lower cylinder piece 338H. Therefore, the upper cylinder piece 337H is fixed between the projecting ring 361 and the upper piece 334. The lower cylinder piece 338H is fixed between the projecting ring 361 and the lower piece 335.

<Twelfth embodiment>
If a resonance circuit unit that resonates according to the alternating magnetic flux from the power transmission coil unit is used, power transmission from the power transmission device to the power reception device can be performed efficiently even if the distance between the power reception device and the power transmission device is increased. Is called. In the present embodiment, a power receiving device including a resonance circuit unit is described.

  FIG. 24 is a schematic circuit diagram of the power receiving device 300I. The power receiving device 300I is described with reference to FIGS. The same code | symbol is attached | subjected with respect to the element same as 3rd Embodiment. The description related to the third embodiment is applied to elements having the same reference numerals.

  Similarly to the third embodiment, the power receiving device 300I includes a motor 321 and a power receiving coil unit 310. The power receiving device 300I further includes a conversion circuit 340I. Similar to the third embodiment, the conversion circuit 340I includes a rectifying bridge circuit 342 and a smoothing capacitor 343. Unlike the third embodiment, the conversion circuit 340I does not have a resonance capacitor.

  The power receiving device 300I further includes a resonance circuit unit 370. The resonance circuit unit 370 includes a resonance coil 371 surrounding the magnetic cylinder 330 and a resonance capacitor 372 electrically connected to the resonance coil 371. The resonance coil 371 and the resonance capacitor 372 form a closed circuit and are electrically independent from the electric circuit including the motor 321, the power reception coil unit 310, and the conversion circuit 340I (that is, the resonance circuit unit 370 is connected to the motor 321, The coil unit 310 and the conversion circuit 340I have no electrical contact). The resonance circuit unit 370 is designed to resonate with an alternating magnetic flux generated by the power transmission device 200. As a result, a current is efficiently induced in the power receiving coil section 310.

  FIG. 25 is a schematic diagram illustrating a positional relationship among the power transmission coil unit 220, the resonance circuit unit 370, and the power reception coil unit 310. The positional relationship among the power transmission coil unit 220, the resonance circuit unit 370, and the power reception coil unit 310 will be described with reference to FIG.

  The resonance circuit unit 370 is disposed between the power transmission coil unit 220 and the power reception coil unit 310. The resonance circuit unit 370 is magnetically connected to the power transmission coil unit 220 and the power reception coil unit 310, respectively. In the present embodiment, the number of turns of the resonance coil 371 is 80 turns. The number of turns of the winding 311 of the receiving coil unit 310 is 5 turns.

<13th Embodiment>
In the twelfth embodiment, the motor used as the operating unit directly receives the direct current generated by the conversion circuit. Alternatively, the operating unit may have a power storage function. The motor may operate using the stored power. In the present embodiment, a power receiving device including an operation unit having a power storage function is described.

  FIG. 26 is a schematic circuit diagram of the power receiving device 300J. With reference to FIG. 26, power receiving apparatus 300J will be described. The same code | symbol is attached | subjected with respect to the element same as 12th Embodiment. The description related to the twelfth embodiment is applied to elements having the same reference numerals.

  Similarly to the twelfth embodiment, the power receiving device 300J includes a power receiving coil unit 310, a conversion circuit 340I, a resonance circuit unit 370, and a motor 321. The power receiving device 300J further includes a secondary battery 322 electrically connected between the motor 321 and the smoothing capacitor 343. The direct current is output from the smoothing capacitor 343 to the secondary battery 322. As a result, the secondary battery 322 can store electricity. The motor 321 can operate by consuming electric power stored in the secondary battery 322.

<Fourteenth embodiment>
The magnetic cylinder may partially accommodate the operating part. As a result, the power receiving device is reduced in weight. In the present embodiment, an electric toothbrush provided with a magnetic cylinder that partially accommodates the operating portion will be described.

  FIG. 27 is a schematic partial cross-sectional view of the toothbrush 400K. With reference to FIG. 27, toothbrush 400K is further demonstrated. The same code | symbol is attached | subjected with respect to the element same as 5th Embodiment. The description related to the fifth embodiment is applied to elements having the same reference numerals.

  Similar to the fifth embodiment, the toothbrush 400K includes a lower housing 401, an upper housing 402, a brush unit 403, a winding 311, a motor 321, a secondary battery 322, and a circuit board 350. Prepare. The toothbrush 400K further includes a magnetic cylinder 330K.

  The secondary battery 322 is housed inside the magnetic cylinder 330K, while the motor 321 is exposed from the magnetic cylinder 330K. The motor 321 may be fixed to the lower housing 401.

  The principle of this embodiment is suitably used for various devices that require long-distance power transmission. In particular, the principle of this embodiment is suitably used for an electric toothbrush and other small electric devices.

100, 100A ... Power transmission system 220, 220A ... Power transmission coil section 310, 310A ... Power reception coil 311 ... winding 320, 320B ... operating part 330 ... ... Magnetic cylinder 330A ... Magnetic cylinder 330C ... Magnetic cylinder 330D ... .... Magnetic cylinder 330E ... Magnetic cylinder 330F ... Magnetic cylinder 330H ... ······················································································ ...・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ Lower end 333 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Upper end 334 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Upper pieces 335, 335E・ ・ ・ ・ ・ ・ Lower piece 336 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Lower opening 337, 337H ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Upper cylinder piece 338, 338H Lower cylinder piece 339 ... Middle cylinder piece 342 ... Rectifier bridge circuit 351 ... upper joint 352 ... lower joint 361 ... ··································································· Resonant circuit unit 400 400C ... Toothbrush 400D ... ... toothbrush 400E ... toothbrush 400F ... toothbrush 400G ... ... toothbrush 400H ... toothbrush 400K ... toothbrush 401, 401E ... ..... Lower casing

Claims (13)

A power transmission coil section for generating an alternating magnetic flux;
A power receiving coil unit that is magnetically coupled to the power transmission coil unit and in which a current corresponding to the alternating magnetic flux is induced;
The non-contact power transmission system, wherein the power receiving coil unit includes a cylindrical magnetic body and a winding surrounding the magnetic body. The magnetic body includes a cylindrical portion that defines an internal space that accommodates an operation portion that performs a predetermined operation by electric power acquired by the current, and a first wall portion that at least partially closes the internal space,
The power transmission system according to claim 1, wherein the first wall portion is disposed between the operation unit and the power transmission coil unit. The tube portion includes a first end portion, and a second end portion that is further away from the power transmission coil portion than the first end portion,
The power transmission system according to claim 2, wherein the first wall portion at least partially closes a first opening defined by the first end portion.   The power transmission system according to claim 3, wherein the first wall portion is separable from the cylindrical portion. A housing that houses the power receiving coil section;
The magnetic body includes a cylindrical portion that defines an internal space that accommodates an operation portion that performs a predetermined operation by electric power acquired by the current, and a second wall portion that at least partially closes the internal space,
2. The power transmission system according to claim 1, wherein the second wall portion cooperates with the housing to confine the operating portion in the internal space. The cylindrical portion includes a first end facing the housing, and a second end spaced away from the power transmission coil portion than the first end,
The power transmission system according to claim 5, wherein the second wall portion at least partially closes a second opening defined by the second end portion.   The electric power according to any one of claims 2 to 6, wherein the tube portion includes a first tube portion and a second tube portion arranged in alignment with the first tube portion. Transmission system.   The power transmission system according to claim 7, wherein the second cylinder part is disposed apart from the first cylinder part.   The power transmission system according to claim 8, wherein the power receiving coil unit includes a spacer that maintains a distance between the first tube unit and the second tube unit.   The power transmission system according to claim 9, wherein the spacer is a non-magnetic material. A rectifier that rectifies the current flowing through the power receiving coil;
The power transmission system according to claim 2, wherein the power is acquired by the current that has passed through the rectifying unit. Between the power transmission coil unit and the power reception coil unit, further comprising a resonance circuit unit magnetically connected to the power reception coil unit,
The resonance circuit unit resonates according to the alternating magnetic flux, and induces the current in the power receiving coil unit that is electrically independent from the resonance circuit unit. The power transmission system according to item. A power receiving device in which a current according to an alternating magnetic flux is induced,
A cylindrical magnetic body,
A winding through which the current flows;
An operation unit that performs a predetermined operation with the electric power acquired by the current,
The magnetic body includes a cylindrical portion that houses the operating portion,
The power receiving device, wherein the winding surrounds the cylindrical portion.

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