Power transmission device

Abstract

A power transmission device for contactlessly transmitting power to another power transmission device is provided with: annular coils (22, 44) for contactlessly transmitting or receiving power; and a ring-shaped shield member (51) disposed on the opposite side to the other power transmission device side with respect to the coil in the power transmission direction. The shielding member is disposed so as to at least partially overlap with the coil when viewed in the power transmission direction, and so that, when viewed in the power transmission direction, an inner circumference of the shielding member is located outside of a position that is inside four times the length of a gap between the coil and the shielding member from the inner circumference of the coil.

Description

Technical Field

[0001] The present disclosure relates to a power transmission device. Background Art

[0002] According to the prior art, a ground power supply device that transmits power to a moving vehicle is known (for example, Japanese Patent Publication No. 2020-150754). In particular, the ground power supply device described in Japanese Patent Publication No. 2020-150754 has a power transmission coil and a shielding member that shields the electromagnetic field of the power transmission coil, and when viewed from the surface side of the road, the power transmission coil is arranged on the inner side of the shielding member. Furthermore, Japanese Patent Publication No. 2020-150754 discloses that a sub-shielding member is provided on the inner side of the shielding member. Summary of the invention

[0003] In a power transmission device such as the ground power supply device described in Japanese Patent Application Laid-Open No. 2020-150754, there is room for improvement in the structure and arrangement of the shielding member in order to efficiently reduce the loss due to the leakage magnetic field.

[0004] In view of the above problems, an object of the present disclosure is to provide a power transmission device having a shield member capable of efficiently reducing a loss due to a leakage magnetic field.

[0005] The gist of the present disclosure is as follows.

[0006] (1) A power transmission device for transmitting power to another power transmission device in a non-contact manner, The power transmission device comprises: A toroidal coil that sends or receives power contactlessly; and The annular shielding member is arranged on the side of the coil opposite to the other power transmission device in the power transmission direction. The shielding member is configured to at least partially overlap with the coil when viewed along the direction of power transmission, and when viewed along the direction of power transmission, the inner periphery of the shielding member is located outside compared to a position inside of a length of 4 times the gap between the coil and the shielding member from the inner periphery of the coil. (2) According to the power transmission device described in (1) above, the shield member is configured so that, when viewed along the power transmission direction, the outer periphery of the shield member is located inside a position outside the outer periphery of the coil that is four times the length of the gap. (3) According to the power transmission device described in (1) or (2) above, the shielding member is configured so that, when viewed along the power transmission direction, the outer periphery of the shielding member is located outside compared to a position outside the outer periphery of the coil that is twice the length of the gap, and / or the inner periphery of the shielding member is located inside compared to a position inside the inner periphery of the coil that is twice the length of the gap. (4) A power transmission device for transmitting power to another power transmission device in a non-contact manner, The power transmission device comprises: A ring-shaped coil that sends or receives power contactlessly; a shielding member disposed on a side of the coil opposite to the other power transmission device side in the power transmission direction; and An annular magnetic member is disposed between the coil and the shielding member. The shielding member is configured to at least partially overlap with the coil when viewed along the direction of transmission of the electric power, and when viewed along the direction of transmission of the electric power, an inner periphery of the shielding member is located outside compared to a position inside of the inner periphery of the coil and the inner periphery of the magnetic member that is 4 times the length of the gap between the coil and the shielding member. (5) According to the power transmission device described in (4) above, the shielding member is configured so that, when viewed along the transmission direction of the power, the outer periphery of the shielding member is located on the inner side compared to a position on the outer side that is 4 times the length of the gap from one of the outer peripheries of the coil and the outer periphery of the magnetic member that is located on the outer side. (6) According to the power transmission device described in (4) or (5) above, the shielding member is configured so that, when viewed along the transmission direction of the power, the outer periphery of the shielding member is located outside compared to a position that is twice the length of the gap outside of the outer periphery of the coil and the outer periphery of the magnetic member, and / or the inner periphery of the shielding member is located inside compared to a position that is twice the length of the gap inside of the outer periphery of the coil and the outer periphery of the magnetic member. (7) In the power transmission device according to any one of (1) to (6) above, the coil is configured so that its entirety extends on a plane parallel to a road surface, and the shielding member is configured so that its entirety extends on a plane parallel to the road surface. (8) The power transmission device according to any one of (1) to (6) above, wherein the shield member is arranged to extend in a direction having at least a portion of a component in a transmission direction of the power. (9) In the power transmission device described in (8) above, an outer periphery of the shield member extends in a transmission direction of the power. (10) The power transmission device according to any one of (1) to (9) above, which is a ground power supply device for transmitting electric power to a vehicle in a contactless manner, wherein the coil is arranged in a road in which steel bars are buried. (11) The power transmission device according to (10) above is characterized in that the metal embedded object is configured so that the distance between it and the coil is less than 400 mm, or the distance between it and the coil is less than twice the distance between the power receiving coil of a vehicle that receives power in a non-contact manner and the coil. (12) The power transmission device according to any one of (1) to (11) above, further comprising a converter circuit that supplies power to the coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a diagram schematically showing the configuration of a contactless power supply system including a ground power supply device. Figure 2 This is a diagram schematically showing a cross section of an underground section of a road in which a power transmission coil is buried. Figure 3 It is a diagram schematically showing the configuration of a power transmission coil and a shield member. Figure 4 This is a diagram showing the relationship between the amount of one-side protrusion of the shield member from the power transmission coil and the loss generated in the reinforcing steel bar. Figure 5 It is a diagram schematically showing the configuration of a power transmission coil and a shield member. Figure 6 The figure schematically shows the configuration of the power transmission coil, the core, and the shield member according to the second embodiment. Figure 3 Same picture. Figure 7 The relationship between the one-side protrusion amount of the shield member 51 from the iron core 52 and the loss generated in the reinforcing steel bar is shown. Figure 8 The figure schematically shows the configuration of the power transmission coil and the shield member according to the third embodiment. Figure 3 Same picture. Fig. 9 It represents the relationship between the protruding length of the second portion of the shielding member from the first portion and the loss generated in the reinforcing steel bar. DETAILED DESCRIPTION

[0008] Hereinafter, the embodiment will be described in detail with reference to the drawings. In the following description, the same reference numerals are given to the same components.

[0009] First embodiment <Overview of the contactless power supply system> Figure 1 1 is a diagram schematically showing the structure of a contactless power supply system 100 including a ground power supply device 1 according to the first embodiment. The contactless power supply system 100 includes a ground power supply device 1 installed on a road R and a vehicle 5 capable of receiving power from the ground power supply device 1. In the contactless power supply system 100, contactless power transmission using magnetic field resonance coupling (magnetic field resonance) is performed from the ground power supply device 1 to the vehicle 5. The ground power supply device 1 functions as a power transmission device for transmitting power to the vehicle 5 in a contactless manner. In addition, the vehicle 5 functions as a power transmission device for transmitting power to the ground power supply device 1 in a contactless manner. In this embodiment, contactless power transmission is performed not only when the vehicle 5 is parked, but also when the vehicle 5 is driving.

[0010] The ground power supply device 1 includes a power transmission unit 32 configured to transmit power to the vehicle 5 in a non-contact manner, and the vehicle 5 includes a power receiving unit 14 configured to receive power in a non-contact manner. When power is supplied to the power transmission unit 32 of the ground power supply device 1, a magnetic field is generated by the power transmission coil 44 of the power transmission unit 32. If the power receiving coil 22 of the power receiving unit 14 of the vehicle 5 is located on the power transmission coil 44, current flows through the power receiving coil 22 due to the magnetic field generated by the power transmission coil 44, thereby receiving power through the power receiving unit 14.

[0011] <Vehicle Configuration> Next, refer to Figure 1 The structure of the vehicle 5 will be described. Figure 1 As shown, the vehicle 5 has a motor 11, a battery 12, a power control unit (PCU) 13, a power receiving unit 14, and an electronic control unit (ECU) 15. The vehicle 5 is an electric vehicle (BEV) in which the motor 11 drives the vehicle 5, or a hybrid vehicle (HEV) in which the motor 11 and an internal combustion engine drive the vehicle 5.

[0012] The motor 11 is, for example, an AC synchronous motor, and functions as a motor and a generator. When the motor 11 functions as a motor, it is driven using the electric power stored in the battery 12 as a power source. The output of the motor 11 is transmitted to the wheels via a speed reducer and an axle.

[0013] The battery 12 is composed of a rechargeable secondary battery, such as a lithium-ion battery, a nickel-metal hydride battery, etc. The battery 12 stores the power required for the vehicle 5 to travel (for example, the driving power of the motor 11). If the power received by the power receiving unit 14 is supplied to the battery 12, the battery 12 is charged. If the battery 12 is charged, the state of charge (SOC: State Of Charge) of the battery 12 is restored. In addition, the battery 12 can also be charged by an external power source other than the ground power supply device 1 via a charging port provided in the vehicle 5.

[0014] The PCU 13 is electrically connected to the motor 11 and the battery 12. The PCU 13 includes a converter, a boost converter, and a DC / DC converter. The converter converts the DC power supplied from the battery 12 into AC power, and supplies the AC power to the motor 11. When the power stored in the battery 12 is supplied to the motor 11, the boost converter boosts the voltage of the battery 12 as needed. When the power stored in the battery 12 is supplied to electronic devices such as headlights, the DC / DC converter steps down the voltage of the battery 12.

[0015] The power receiving unit 14 receives electric power from the power transmitting unit 32 and supplies the received electric power to the battery 12. The power receiving unit 14 includes a power receiving side resonance circuit 21, a power receiving side rectification circuit 24, and a charging circuit 25.

[0016] The receiving-side resonant circuit 21 is arranged at the bottom of the vehicle 5 so that the distance from the road surface is small. The receiving-side resonant circuit 21 includes a receiving coil 22 and a receiving-side resonant capacitor 23. In the present embodiment, the receiving coil 22 is arranged so that the distance from the road surface becomes a predetermined distance. The receiving coil 22 is arranged so that a current flows through the receiving coil 22 after a magnetic field is generated around it. The receiving coil 22 and the receiving-side resonant capacitor 23 constitute a resonator. Various parameters of the receiving coil 22 and the receiving-side resonant capacitor 23 (the outer diameter and inner diameter of the receiving coil 22, the number of turns of the receiving coil 22, the capacitance of the receiving-side resonant capacitor 23, etc.) are determined so that the resonant frequency of the receiving-side resonant circuit 21 coincides with the resonant frequency of the transmitting-side resonant circuit 43. In addition, if the deviation between the resonant frequency of the receiving-side resonant circuit 21 and the resonant frequency of the transmitting-side resonant circuit 43 is small, for example, the resonant frequency of the receiving-side resonant circuit 21 is within the range of ±10% of the resonant frequency of the transmitting-side resonant circuit 43, the resonant frequency of the receiving-side resonant circuit 21 does not necessarily have to be consistent with the resonant frequency of the transmitting-side resonant circuit 43.

[0017] The receiving-side rectifier circuit 24 is electrically connected to the receiving-side resonance circuit 21 and the charging circuit 25. The receiving-side rectifier circuit 24 rectifies the AC power supplied from the receiving-side resonance circuit 21 and converts it into DC power, and supplies the DC power to the charging circuit 25. The receiving-side rectifier circuit 24 is, for example, an AC / DC converter.

[0018] The charging circuit 25 is electrically connected to the power receiving side rectifier circuit 24 and the battery 12. The charging circuit 25 converts the DC power supplied from the power receiving side rectifier circuit 24 into the voltage level of the battery 12 and supplies it to the battery 12. When the power transmitted from the power transmission unit 32 is supplied to the battery 12 via the power receiving unit 14, the battery 12 is charged. The charging circuit 25 is, for example, a DC / DC converter.

[0019] The ECU 15 performs various controls on the vehicle 5. For example, the ECU 15 is electrically connected to the charging circuit 25 of the power receiving unit 14, and controls the charging circuit 25 to control charging of the battery 12 by the power transmitted from the power transmitting unit 32. In addition, the ECU 15 is electrically connected to the PCU 13, and controls the PCU 13 to control reception / transmission of power between the battery 12 and the motor 11.

[0020] <Configuration of ground power supply equipment> Next, refer to Figure 1 The structure of the ground power supply device 1 is briefly described. Figure 1 As shown, the ground power supply device 1 includes a power source 31 , a power transmission unit 32 , and a controller 33 .

[0021] The power supply 31 supplies power to the power transmission unit 32. The power supply 31 is, for example, a commercial AC power supply that supplies single-phase AC power. Alternatively, the power supply 31 may be another AC power supply that supplies three-phase AC power, or a DC power supply such as a fuel cell.

[0022] The power transmission unit 32 transmits the power supplied from the power source 31 to the vehicle 5 in a contactless manner. The power transmission unit 32 includes a power transmission side rectifier circuit 41, a converter circuit 42, and a power transmission side resonant circuit 43. Figure 1 As shown, the power transmission side resonance circuit 43 of the power transmission unit 32, in particular, the power transmission coil 44 of the power transmission side resonance circuit 43 is buried in a row in the road R (underground) on which the vehicle 5 travels, for example, in the center of the lane on which the vehicle 5 travels. In addition, the power transmission side rectifier circuit 41 and the converter circuit 42 of the power transmission unit 32 may be buried underground or may be arranged above ground.

[0023] The power transmission side rectifier circuit 41 is electrically connected to the power supply 31 and the converter circuit 42. The power transmission side rectifier circuit 41 rectifies the AC power supplied from the power supply 31 and converts it into DC power, and supplies the DC power to the converter circuit 42. The power transmission side rectifier circuit 41 is, for example, an AC / DC converter. In the present embodiment, one power transmission side rectifier circuit 41 is provided in one power transmission unit 32. In addition, when the power supply 31 is a DC power supply, the power transmission side rectifier circuit 41 may be omitted.

[0024] The converter circuit 42 is electrically connected to the power transmission side rectification circuit 41 and the power transmission side resonance circuit 43. The converter circuit 42 converts the DC power supplied from the power transmission side rectification circuit 41 into AC power (high-frequency AC power) having a higher frequency than the AC power of the power source 31, and supplies the high-frequency AC power to the power transmission side resonance circuit 43. In the present embodiment, the power transmission unit 32 has the converter circuits 42 corresponding to the number of the power transmission side resonance circuits 43. Each converter circuit 42 is connected to a corresponding one of the different power transmission side resonance circuits 43.

[0025] The power transmission side resonant circuit 43 has a power transmission coil 44 and a power transmission side resonant capacitor 45. The power transmission coil 44 is formed in a ring shape, and generates a magnetic field for contactlessly transmitting power when current flows. The power transmission coil 44 and the power transmission side resonant capacitor 45 constitute a resonator. Various parameters of the power transmission coil 44 and the power transmission side resonant capacitor 45 (the outer diameter and inner diameter of the power transmission coil 44, the number of turns of the power transmission coil 44, the capacitance of the power transmission side resonant capacitor 45, etc.) are determined in such a way that the resonant frequency of the power transmission unit 32 becomes a prescribed set value. The prescribed set value is, for example, 10 kHz to 100 GHz, and preferably 85 kHz determined in accordance with the SAE TIR J2954 standard as a frequency band for contactless power transmission.

[0026] The controller 33 is, for example, a general-purpose computer, and performs various controls of the ground power supply device 1. In particular, the controller 33 is electrically connected to the converter circuit 42 of the power transmission unit 32, and controls the converter circuit 42 in order to control the power transmission performed by the power transmission unit 32. Specifically, for example, the controller 33 determines the power transmission coil 44 on which the vehicle 5 is located based on the output from an arbitrary sensor (not shown), and controls the converter circuit 42 in a manner that supplies power to the determined power transmission coil 44. The controller 33 has a processor that executes various processes, and a memory that stores programs for causing the processor to execute various processes and various data used by the processor when executing various processes.

[0027] In the contactless power supply system 100 configured as described above, Figure 1 When the power receiving coil 22 of the vehicle 5 is facing the power transmission coil 44 of the ground power supply device 1, AC power is supplied to the power transmission side resonance circuit 43, and an alternating magnetic field is generated by the power transmission coil 44. After the alternating magnetic field is generated in this way, the vibration of the alternating magnetic field is transmitted to the power receiving coil 22. As a result, an induced current flows in the power receiving coil 22 due to electromagnetic induction, and an induced electromotive force is generated in the power receiving side resonance circuit 21 by the induced current. That is, electric power is transmitted from the power transmission unit 32 including the power transmission side resonance circuit 43 to the power receiving unit 14 including the power receiving side resonance circuit 21.

[0028] <Structure around the power transmission coil> Next, refer to Figure 2 and Figure 3 , the structure around the power transmission coil 44 buried in the road R will be described. Figure 2 It is a diagram schematically showing a cross section of the underground of the road R in which the power transmission coil 44 is buried.

[0029] like Figure 2 As shown, the road R is formed in a multi-layered shape, and a surface layer R1, an intermediate layer R2, a base layer R3, and a roadbed R4 are sequentially arranged from the surface. The surface layer R1 is a layer exposed on the road surface, and is formed of a material having appropriate anti-skid properties, such as an asphalt mixture such as high-performance asphalt, in a manner that allows the vehicle 5 traveling on the surface layer R1 to travel safely. The intermediate layer R2 is a layer in which the power transmission coil 44 arranged below the surface layer R1 is buried, and is formed of an asphalt mixture such as functional asphalt (Asmatic Asphalt). The base layer R3 is a layer arranged between the intermediate layer R2 and the roadbed R4 to disperse the traffic load, and is composed of, for example, reinforced concrete. Therefore, in the base layer R3, steel bars S are buried in a plane parallel to the road surface of the road R. In particular, in the present embodiment, the steel bars S are buried in the base layer R3 in a grid shape, but as long as they are buried in a plane parallel to the road surface of the road R, they can be buried in any manner. The roadbed R4 is arranged between the base layer R3 and the roadbed (not shown), and is composed of, for example, a cement stabilized mixture. In this embodiment, since the intermediate layer R2 in which the power transmission coil 44 is buried is located closer to the road surface than the base layer R3 in which the reinforcing steel bars S are buried, the power transmission coil 44 is provided between the road surface and the reinforcing steel bars S. In other words, the power transmission coil 44 is arranged closer to the road surface than the reinforcing steel bars S.

[0030] Specifically, in the present embodiment, the thickness of the surface layer R1 is, for example, 20 mm to 60 mm, 30 mm to 50 mm, or about 40 mm. In addition, the thickness of the intermediate layer R2 is, for example, 20 mm to 60 mm, 30 mm to 50 mm, or about 40 mm. Further, the thickness of the base layer R3 is, for example, 110 mm to 310 mm, 160 mm to 260 mm, or about 210 mm. In addition, the thickness of the roadbed R4 is 100 mm to 300 mm, 150 mm to 250 mm, or about 200 mm.

[0031] In addition, in the present embodiment, the steel bars S are arranged, for example, 30 mm to 110 mm, 50 mm to 90 mm, or about 70 mm below the upper surface of the base layer R3 (the boundary surface between the base layer R3 and the intermediate layer R2). In other words, the steel bars S are arranged below 1 / 2 to 1 / 4, or about 1 / 3 of the thickness of the base layer R3 from the upper surface of the base layer R3. Furthermore, the steel bars S are arranged to extend in a direction parallel to the driving direction of the vehicle 5 (longitudinal direction) and in a direction perpendicular to the driving direction of the vehicle 5 (lateral direction). The steel bars S extending in a direction parallel to the driving direction of the vehicle 5 are arranged at intervals of 75 mm to 300 mm, 100 mm to 200 mm, or about 150 mm in a direction perpendicular to the driving direction of the vehicle 5. On the other hand, the reinforcement S extending in the direction perpendicular to the traveling direction of the vehicle 5 is arranged in a direction parallel to the traveling direction of the vehicle 5 at intervals of 150 mm to 450 mm, 200 mm to 400 mm, or approximately 300 mm.

[0032] However, after the steel bar is arranged below the power transmission coil 44, when the alternating magnetic field is generated by the power transmission coil 44, the magnetic flux passes through the steel bar and generates eddy current in the steel bar, and the magnetic loss caused by transmission increases. Figure 2 As shown in FIG. 1 , an annular shield member 51 is provided between the power transmission coil 44 and the reinforcing steel bar S. As shown in FIG.

[0033] Figure 3 It is a diagram schematically showing the configuration of the power transmission coil 44 and the shield member 51 . Figure 3 One power transmission coil 44 and one shield member 51 corresponding to the power transmission coil 44 are shown. Figure 3 (A) is a top view of the power transmission coil 44 and the shield member 51. Figure 3 (B) is a cross-sectional side view of the power transmission coil 44 and the shield member 51 .

[0034] like Figure 3 As shown in FIG. 1 , the power transmission coil 44 is formed into a quadrilateral ring shape with rounded apex angles. Figure 2 As shown in FIG. 4 , the power transmission coil 44 is arranged so that its entirety extends on a plane parallel to the road surface of the road R. Figure 1As shown, when the power receiving coil 22 of the vehicle 5 is located on the power transmitting coil 44, power is transmitted from the power transmitting coil 44 to the power receiving coil 22. Therefore, in the present embodiment, the transmission direction D of the power from the power transmitting coil 44 to the power receiving coil 22 (hereinafter referred to as "power transmission direction D") is a direction perpendicular to the road surface of the road R. In addition, the power transmitting coil 44 does not necessarily have to be formed into a quadrilateral ring with rounded apex angles, and may be formed into a circular ring, for example. The power transmitting coil 44 does not necessarily extend on a plane parallel to the road surface of the road R, and may extend on a plane inclined relative to the road surface, for example.

[0035] The shield member 51 is used to shield the leakage magnetic field from the power transmission coil 44. The shield member 51 is formed of a material having a relative magnetic permeability of less than 1 in the frequency band for contactless power transmission. Specifically, the shield member 51 is formed of a conductive non-magnetic material such as aluminum, nickel, or copper.

[0036] like Figure 3 As shown, the shielding member 51 is formed in a flat plate shape (see Figure 3 (B)), and form a quadrilateral ring with rounded apex (refer to Figure 3 (A)). In addition, the width Ws of the annular portion of the shielding member 51 (the length in a plane horizontal to the road surface of the road R and in a direction perpendicular to the circumference of the annular portion of the shielding member 51) is greater than the width Wc of the annular portion of the power transmission coil 44 (the length in a plane horizontal to the road surface of the road R and in a direction perpendicular to the circumference of the annular portion of the power transmission coil 44). In addition, the shielding member 51 only needs to have the same shape as the power transmission coil 44, and does not necessarily have to be formed into a quadrilateral ring with rounded vertices. For example, it can be formed into a quadrilateral ring with unrounded vertices, a polygonal ring other than a quadrilateral, or a circular ring.

[0037] In addition, if Figure 3 As shown, the entire shielding member 51 is arranged on a plane parallel to the plane on which the power transmission coil 44 is provided. Thus, the shielding member 51 is arranged so that the entire shielding member 51 extends on a plane parallel to the road surface of the road R. In addition, the shielding member 51 is not necessarily arranged in a plane parallel to the plane on which the power transmission coil 44 is provided, and for example, it may extend on a plane inclined relative to the plane on which the power transmission coil 44 is provided.

[0038] The shield member 51 is disposed on the opposite side of the power transmission coil 44 from the road surface in the power transmission direction D. Thus, when the vehicle 5 is located on the power transmission coil 44, the shield member 51 is disposed on the opposite side of the power transmission coil 44 from the vehicle 5 in the power transmission direction D.

[0039] In addition, if Figure 3As shown, the shield member 51 is arranged so as to overlap the power transmission coil 44 when viewed in the power transmission direction D. In particular, in the present embodiment, the shield member 51 is arranged so as to overlap the entire power transmission coil 44 when viewed in the power transmission direction D.

[0040] In addition, in the present embodiment, the shield member 51 extends in a manner that protrudes inward from the inner periphery of the power transmission coil 44 when viewed in the power transmission direction D. In particular, in the present embodiment, when the size of the gap between the power transmission coil 44 and the shield member 51 in the power transmission direction D is G, the shield member 51 is arranged so that when viewed in the power transmission direction D, the inner periphery of the shield member 51 is located outside compared to a position inside the inner periphery of the power transmission coil 44 that is four times the length of the gap G. Further, the shield member 51 is arranged so that when viewed in the power transmission direction D, the inner periphery of the shield member 51 is located inside compared to a position inside the inner periphery of the power transmission coil 44 that is two times the length of the gap G. That is, the distance Lin between the inner periphery of the shield member 51 and the inner periphery of the power transmission coil 44 (the protrusion amount of the shield member 51 from the inner periphery of the power transmission coil 44) is a length of two to four times the gap G (2G≤Lin≤4G).

[0041] In addition, in the present embodiment, the shield member 51 extends in a manner that protrudes outward from the outer periphery of the power transmission coil 44 when viewed in the power transmission direction D. In particular, in the present embodiment, the shield member 51 is configured so that when viewed in the power transmission direction D, the outer periphery of the shield member 51 is located inside compared to a position outside of the outer periphery of the power transmission coil 44 that is 4 times the length of the gap G. Further, the shield member 51 is configured so that when viewed in the power transmission direction D, the outer periphery of the shield member 51 is located outside compared to a position outside of the outer periphery of the power transmission coil 44 that is 2 times the length of the gap G. That is, the distance Lout between the outer periphery of the shield member 51 and the outer periphery of the power transmission coil 44 (the protrusion amount of the shield member 51 from the outer periphery of the power transmission coil 44) is set to a length of 2 to 4 times the gap G (2G≤Lout≤4G).

[0042] Figure 4 : is a graph showing the relationship between the one-side protrusion amount L of the shield member 51 from the power transmission coil 44 and the loss generated in the steel bar. In particular, Figure 4 The thickness of the surface layer R1, the intermediate layer R2, the base layer R3 and the roadbed R4 are respectively set to 40 mm, 40 mm, 210 mm and 200 mm, and the steel bars S are arranged at intervals of 70 mm from the upper surface of the base layer R3, 150 mm in the horizontal direction and 300 mm in the vertical direction. Figure 4 The case where the gap between the shield member 51 and the power transmission coil 44 is 6 mm and the case where the gap is 12 mm are shown.

[0043] like Figure 4 As shown, when the gap is 6 mm, the loss generated in the steel bar becomes sufficiently small when the protrusion is 12.5 mm, and hardly changes after the protrusion exceeds 25 mm. Similarly, when the gap is 12 mm, the loss generated in the steel bar becomes sufficiently small when the protrusion is 25 mm, and hardly changes after the protrusion exceeds 50 mm. Therefore, as in the present embodiment, by configuring the shielding member 51 so that the protrusion L becomes 2 to 4 times the length of the gap G, it is possible to sufficiently reduce the loss generated in the steel bar while minimizing the material used as the shielding member 51.

[0044] <Modification>

[0045] In the above embodiment, the shield member 51 is formed so as to protrude inward from the inner periphery of the power transmission coil 44 and protrude outward from the outer periphery of the power transmission coil 44 when viewed in the power transmission direction D. Figure 5 As shown in (A) of FIG. 1 , the shield member 51 is formed so as not to protrude from the power transmission coil 44 when viewed in the power transmission direction D, and the entire shield member 51 overlaps the entire power transmission coil 44. Figure 4 As shown, even when the protrusion amount L is 0, the loss generated in the steel bar is relatively small, so when the entire shielding member 51 overlaps the entire power transmission coil 44, the loss can be suppressed to a relatively small level. In addition, the shielding member 51 can also be formed so that when viewed along the power transmission direction D, only one of the outer periphery and the inner periphery of the shielding member 51 is coplanar with the outer periphery or the inner periphery of the power transmission coil 44.

[0046] Or, if Figure 5 As shown in (B), the shielding member 51 may be formed so that, when viewed along the power transmission direction D, its inner periphery is retracted outward from the inner periphery of the power transmission coil 44, and its outer periphery is retracted inward from the outer periphery of the power transmission coil 44. In addition, the shielding member 51 may be formed so that, when viewed along the power transmission direction D, only one of the outer periphery and the inner periphery of the shielding member 51 is retracted from the outer periphery or the inner periphery of the power transmission coil 44. In either case, the shielding member 51 is formed so as to at least partially overlap with the power transmission coil 44 when viewed along the power transmission direction D. Figure 5 (A) and Figure 5 In any case of (B), the shielding member 51 is configured so that its outer periphery is located inside compared to a position on the outside that is four times the length of the gap G from the outer periphery of the power transmission coil 44, and its inner periphery is located outside compared to a position on the inside that is four times the length of the gap G from the inner periphery of the power transmission coil 44.

[0047] In addition, in the above-mentioned embodiment, as a component causing magnetic loss, the case where steel bars S are buried in the road is used as an example for explanation. However, magnetic loss is also generated for metal buried objects other than steel bars S, such as metal gas pipes, water pipes, wires for system power distribution, and buried pipes for wires. Therefore, even in the case where metal buried objects other than steel bars S are buried, the power transmission device involved in this embodiment can be used in the same way. In particular, when the distance between the metal buried object and the power transmission coil 44 is short, the shielding member 51 becomes necessary, and when the distance between the metal buried object and the power transmission coil 44 is less than 400 mm, or less than twice the power transmission distance, the effect obtained by providing the shielding member 51 becomes greater. In addition, the power transmission distance is the distance between the power receiving coil 22 and the power transmission coil 44 set at a specified height of the vehicle 5.

[0048] Second embodiment Next, refer to Figure 6 and Figure 7 , a ground power supply device 1 according to a second embodiment is described. The configuration of the ground power supply device 1 according to the second embodiment is basically the same as that of the ground power supply device 1 according to the first embodiment. The following description will focus on the parts different from the ground power supply device 1 according to the first embodiment.

[0049] Figure 6 The figure schematically shows the configuration of the power transmission coil 44, the iron core 52, and the shield member 51 according to the second embodiment. Figure 3 Same picture. Figure 6 (A) is a top view of the power transmission coil 44, the iron core 52 and the shield member 51. Figure 6 (B) is a cross-sectional side view of the power transmission coil 44 , the core 52 , and the shield member 51 .

[0050] like Figure 6 As shown, in this embodiment, in the power transmission direction D, an iron core 52 is provided between the power transmission coil 44 and the shielding member 51. The iron core 52 is an example of a magnetic material formed of a magnet with high magnetic permeability. The iron core is formed of a soft magnetic material such as ferrite, powder core, iron powder core, etc. By providing the iron core 52, a passage for the magnetic flux is generated, and as a result, the inductance of the power transmission coil 44 can be increased.

[0051] like Figure 6 As shown, the core 52 is formed into a flat plate shape (see Figure 6 (B)), and formed into a quadrilateral ring with rounded apex angles (refer to Figure 6(A)). In addition, the width Wr of the annular portion of the iron core 52 (the length in a plane horizontal to the road surface of the road R and in a direction perpendicular to the circumferential direction of the annular portion of the iron core 52) is greater than the width Wc of the annular portion of the power transmission coil 44 and is smaller than the width Ws of the shielding member 51. In addition, the iron core 52 only needs to have the same shape as the power transmission coil 44, and does not necessarily have to be formed into a quadrilateral ring with rounded apex angles. For example, it can be formed into a quadrilateral ring with unrounded apex angles, a polygonal ring other than a quadrilateral, or a circular ring.

[0052] In addition, if Figure 6 As shown, the entire iron core 52 is arranged on a plane parallel to the plane where the power transmission coil 44 is provided. Thus, the iron core 52 is arranged so that its entirety extends on a plane parallel to the road surface of the road R. In addition, the iron core 52 is not necessarily arranged in a plane parallel to the plane where the power transmission coil 44 is provided, and for example, it may extend on a plane inclined relative to the plane where the power transmission coil 44 is provided.

[0053] In addition, if Figure 6 As shown, the iron core 52 is configured so as to overlap with the power transmission coil 44 when viewed along the power transmission direction D. In particular, in the present embodiment, the iron core 52 is configured so as to overlap with the entire power transmission coil 44 when viewed along the power transmission direction D. In addition, in the present embodiment, the iron core 52 is formed so as to protrude inwardly from the inner periphery of the power transmission coil 44 when viewed along the power transmission direction D. Further, in the present embodiment, the iron core 52 is formed so as to protrude outwardly from the outer periphery of the power transmission coil 44 when viewed along the power transmission direction D. In addition, the iron core 52 may also be formed so as to protrude from only one of the inner periphery and the outer periphery of the power transmission coil 44.

[0054] In addition, in the present embodiment, the shield member 51 extends in a manner that protrudes inward from the inner periphery of the iron core 52 when viewed in the power transmission direction D. In particular, in the present embodiment, when the size of the gap between the power transmission coil 44 and the shield member 51 in the power transmission direction D is G, the shield member 51 is arranged so that when viewed in the power transmission direction D, the inner periphery of the shield member 51 is located outside compared to a position inside the inner periphery of the iron core 52 that is four times the length of the gap G. Further, the shield member 51 is arranged so that when viewed in the power transmission direction D, the inner periphery of the shield member 51 is located inside compared to a position inside the inner periphery of the iron core 52 that is two times the length of the gap G. That is, the distance L'in between the inner periphery of the shield member 51 and the inner periphery of the iron core 52 (the protrusion amount of the shield member 51 from the inner periphery of the iron core 52) is a length of two to four times the gap G (2G≤L'in≤4G).

[0055] In addition, in the present embodiment, the shielding member 51 extends in a manner protruding outward from the outer periphery of the core 52 when viewed in the power transmission direction D. In particular, in the present embodiment, the shielding member 51 is configured so that when viewed in the power transmission direction D, the outer periphery of the shielding member 51 is located inside compared to a position outside of the outer periphery of the core 52 that is 4 times the length of the gap G. Further, the shielding member 51 is configured so that when viewed in the power transmission direction D, the outer periphery of the shielding member 51 is located outside compared to a position outside of the outer periphery of the core 52 that is 2 times the length of the gap G. That is, the distance L'out between the outer periphery of the shielding member 51 and the outer periphery of the core 52 (the protrusion amount of the shielding member 51 from the outer periphery of the core 52) is 2 to 4 times the length of the gap G (2G≤L'out≤4G).

[0056] Figure 7 The relationship between the one-side protrusion amount L' of the shield member 51 from the iron core 52 and the loss generated in the steel bar is shown. In particular, Figure 7 Set the road R and reinforcement S to Figure 4 The same conditions as in are shown when the interval between the power transmission coil 44 and the iron core 52 is 5 mm, and the interval between the iron core 52 and the shielding member 51 is 5 mm. In particular, Figure 7 The case where the protrusion amount of the iron core 52 from the power transmission coil 44 when viewed in the power transmission direction D is 0 mm and the case where it is 12.5 mm are shown.

[0057] like Figure 7 As shown, regardless of whether the iron core 52 protrudes from the power transmission coil 44, as long as the protrusion amount L' of the shielding member 51 from the iron core 52 is the same, the loss generated in the steel bar is of the same degree. On the other hand, even if the protrusion amount L' of the shielding member 51 from the power transmission coil 44 is the same, if the protrusion amount L' of the shielding member 51 from the iron core 52 is different, the loss generated in the steel bar changes. For example, the case where the protrusion amount L' of the iron core 52 from the power transmission coil 44 is 12.5 mm and the protrusion amount L' of the shielding member 51 from the iron core 52 is 0 mm is compared with the case where the protrusion amount L' of the iron core 52 from the power transmission coil 44 is 0 mm and the protrusion amount L' of the shielding member 51 from the iron core 52 is 12.5 mm. In either case, the protrusion amount L' of the shielding member 51 from the power transmission coil 44 is the same as 12.5 mm, but there is a large difference in the loss generated in the steel bar. In this embodiment, when the iron core 52 is provided between the power transmission coil 44 and the shield member 51 , the protrusion amount L′ of the shield member 51 from the iron core 52 is set based on the gap G. Therefore, the loss generated in the reinforcing steel bars can be appropriately reduced.

[0058] In addition, in the present embodiment, the iron core 52 protrudes inwardly compared to the inner circumference of the power transmission coil 44, and the inner circumference of the iron core 52 is located on the inner side of the inner circumference of the power transmission coil 44. However, the inner circumference of the iron core 52 may be located on the outer side of the inner circumference of the power transmission coil 44. In this case, the shielding member 51 is formed such that the distance between its inner circumference and the inner circumference of the power transmission coil 44 is 2 to 4 times the length of the gap G, as in the first embodiment described above. Thus, the shielding member 51 is configured such that, when viewed along the power transmission direction D, the inner circumference of the shielding member 51 is located on the inner side of the inner circumference of the power transmission coil 44 and the inner circumference of the iron core 52, whichever is located on the inner side, by a length of 2 to 4 times the length of the gap G.

[0059] Similarly, in the present embodiment, the iron core 52 protrudes outward compared to the outer periphery of the power transmission coil 44, and the outer periphery of the iron core 52 is located outside the outer periphery of the power transmission coil 44. However, the outer periphery of the iron core 52 may also be located outside the outer periphery of the power transmission coil 44. In this case, the shielding member 51 is formed so that the distance between its outer periphery and the outer periphery of the power transmission coil 44 is 2 to 4 times the length of the gap G, as in the first embodiment described above. Thus, the shielding member 51 is configured so that when viewed along the power transmission direction D, the outer periphery of the shielding member 51 is located outside from the outer periphery of the power transmission coil 44 and the outer periphery of the iron core 52, whichever is located outside, by a length of 2 to 4 times the gap G.

[0060] Third embodiment Next, refer to Figure 8 and Fig. 9 , a ground power supply device 1 according to a third embodiment is described. The structure of the ground power supply device 1 according to the third embodiment is basically the same as that of the ground power supply device 1 according to the first embodiment or the second embodiment. The following description will focus on the parts that are different from the ground power supply device 1 according to the first embodiment and the second embodiment.

[0061] Figure 8 The figure schematically shows the configuration of the power transmission coil 44 and the shield member 51 according to the third embodiment. Figure 3 In the first and second embodiments, the shielding member 51 is a flat plate and is formed in a ring shape. Figure 8 As shown in FIG. 1 , in the present embodiment, the shield member 51 is configured to include a flat plate-shaped and annular first portion 51 a and a cylindrical second portion 51 b .

[0062] The first portion 51a is configured in the same manner as the shielding member in the first embodiment. In addition, the first portion 51a is entirely disposed on a plane parallel to the plane on which the power transmission coil 44 is disposed. On the other hand, the second portion 51b is configured such that its inner surface is connected to the outer periphery of the first portion 51a. Figure 8As shown, the second portion 51b extends in the power transmission direction D. In particular, the second portion 51b extends from the joint portion with the first portion 51a toward the road surface of the road R, that is, toward the vehicle 5 side when the vehicle 5 is located on the power transmission coil 44. Therefore, in the present embodiment, the shielding member 51 is formed in such a way that its outer periphery extends along the power transmission direction D. In addition, the first portion 51a and the second portion 51b of the shielding member 51 may be formed as different monomers and then combined, or may be formed integrally.

[0063] In the present embodiment, the first portion 51a is configured so that the outer periphery of the shielding member 51 is located outside the outer periphery of the power transmission coil 44 by 1 to 4 times the gap G when viewed in the power transmission direction D. In addition, in the present embodiment, the first portion 51a is configured so that the inner periphery of the shielding member 51 is located inside the outer periphery of the power transmission coil 44 by 1 to 4 times the gap G when viewed in the power transmission direction D. Further, in the present embodiment, the second portion 51b is configured so as to extend in the power transmission direction D by a length of 1 to 4 times the gap G.

[0064] Fig. 9 The relationship between the protruding length of the second portion 51b of the shield member 51 from the first portion 51a and the loss generated in the reinforcing steel bar is shown. Fig. 9 The case where the gap G between the first portion 51a of the shield member 51 and the power transmission coil 44 is 6 mm is shown. Fig. 9 The inner periphery of the first portion 51 a is located 12.5 mm from the inner periphery of the power transmission coil 44 and the outer periphery of the first portion 51 a is located 12.5 mm from the outer periphery of the power transmission coil 44 when viewed in the power transmission direction D.

[0065] Fig. 9 The solid line in represents the relationship when the second portion 51b extending in the power transmission direction D is arranged on the outer periphery of the first portion 51a as shown in this embodiment. Fig. 9 The single-dot chain line in represents the relationship when the second portion extending in the power transmission direction D is arranged on the inner periphery of the first portion 51a. Fig. 9 The double-dashed lines in show the relationship when the second portion extending in the power transmission direction D is arranged on the outer periphery and inner periphery of the first portion 51a, respectively. The excess length in these solid lines, single-dashed lines, and double-dashed lines represents the length of the second portion in the power transmission direction D from the junction with the first portion. Further, Fig. 9The dashed line in shows the case where the shield member is extended outward from the first portion 51a (without the second portion extending in the power transmission direction D). The excess length in the dashed line indicates the length between the outer periphery of the portion extended outward from the first portion 51a and the outer periphery of the first portion 51a.

[0066] according to Fig. 9 As can be seen from the solid line and the double-dashed line, by forming the second portion of the shielding member 51 in a manner extending from the outer periphery of the first portion 51a in the power transmission direction D as in the present embodiment, the shielding member 51 is only extended toward the outside ( Fig. 9 Compared with the dotted line in the figure, it can reduce the loss in the steel bar.

[0067] Furthermore, in the above-described embodiment, the second portion 51b is formed so as to extend in the power transmission direction D. However, the second portion 51b only needs to extend so as to have a component in the power transmission direction D, and does not necessarily need to extend in the power transmission direction D. Thus, the second portion 51b may be formed so as to extend obliquely from the outer periphery of the first portion 51a toward the outside and toward the road surface direction of the road R, for example.

[0068] In addition, in the first to third embodiments described above, the shielding member 51 is provided around the power transmission coil 44 of the ground power supply device 1. However, a shielding member may be provided around the power receiving coil 22 of the vehicle 5. In this case, the shielding member is arranged between the power receiving coil 22 and the metal member constituting the body of the vehicle 5, and the loss in the metal member can be reduced by the shielding member.

[0069] As mentioned above, although the preferred embodiment concerning this invention was described, this invention is not limited to these embodiments, Various corrections and changes can be implemented within the description of the scope of claims.

Claims

1. A power transmission device for transmitting power to another power transmission device in a non-contact manner, The power transmission device comprises: A toroidal coil that sends or receives power contactlessly; and The annular shielding member is arranged on the side of the coil opposite to the other power transmission device in the power transmission direction. The shielding member is configured to at least partially overlap with the coil when viewed along the direction of power transmission, and when viewed along the direction of power transmission, the inner periphery of the shielding member is located outside compared to a position inside of a length of 4 times the gap between the coil and the shielding member from the inner periphery of the coil.

2. The power transmission device according to claim 1, wherein: The shield member is arranged such that, when viewed in the power transmission direction, the outer periphery of the shield member is located inside a position outside the outer periphery of the coil that is four times the length of the gap.

3. The power transmission device according to claim 1 or 2, wherein: The shielding member is configured such that, when observed along the direction of electric power transmission, an outer periphery of the shielding member is located outside compared to a position outside the outer periphery of the coil that is twice the length of the gap, and / or an inner periphery of the shielding member is located inside compared to a position inside the inner periphery of the coil that is twice the length of the gap.

4. A power transmission device for transmitting power to another power transmission device in a non-contact manner, The power transmission device comprises: A ring-shaped coil that sends or receives power contactlessly; a shielding member disposed on a side of the coil opposite to the other power transmission device side in the power transmission direction; as well as An annular magnetic member is disposed between the coil and the shielding member. The shielding member is configured to at least partially overlap with the coil when viewed along the direction of transmission of the electric power, and when viewed along the direction of transmission of the electric power, an inner periphery of the shielding member is located outside compared to a position inside of the inner periphery of the coil and the inner periphery of the magnetic member that is 4 times the length of the gap between the coil and the shielding member.

5. The power transmission device according to claim 4, wherein: The shielding member is configured such that, when viewed along the transmission direction of the electric power, the outer periphery of the shielding member is located inside compared to a position outside of one of the outer peripheries of the coil and the outer periphery of the magnetic member that is located outside by 4 times the length of the gap.

6. The power transmission device according to claim 4 or 5, wherein: The shielding member is configured such that, when observed along the transmission direction of the electric power, the outer periphery of the shielding member is located outside compared to a position that is twice the length of the gap outside of the outer periphery of the coil and the outer periphery of the magnetic member, and / or the inner periphery of the shielding member is located inside compared to a position that is twice the length of the gap inside of the outer periphery of the coil and the outer periphery of the magnetic member.

7. The power transmission device according to any one of claims 1 to 6, wherein: The coil is arranged so that its entirety extends in a plane parallel to the road surface. The shielding member is configured so that its entirety extends on a plane parallel to the road surface.

8. The power transmission device according to any one of claims 1 to 7, wherein: The shielding member is configured to extend in a direction having at least a portion of a component of a transmission direction of the electric power.

9. The power transmission device according to claim 8, wherein: An outer periphery of the shield member extends along a transmission direction of the electric power.

10. The power transmission device according to any one of claims 1 to 9, wherein: The power transmission device is a ground power supply device for transmitting electric power to a vehicle in a contactless manner, and the coil is arranged in a road in which a metal embedded object is buried and is located on the road surface side relative to the metal embedded object.

11. The power transmission device according to claim 10, characterized in that: The embedded metal object is arranged so that the distance between the embedded metal object and the coil is 400 mm or less, or the distance between the embedded metal object and the coil is twice or less the distance between the coil and a power receiving coil of a vehicle that receives power in a contactless manner.

12. The power transmission device according to any one of claims 1 to 11, wherein: The power transmission device includes a converter circuit that supplies power to the coil.

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