Coil unit

Abstract

To obtain a coil unit used for a non-contact charging system capable of improving the strength of a device case and of reducing the height of the coil unit.SOLUTION: A coil unit 1 in a non-contact charging system, the coil unit being arranged on the ground or electric automobiles, comprises: a flat plate-like coil case 80; a coil 2 arranged in a spiral shape on a surface of the coil case 80; a second cover member 60 that covers the coil 2 while being arranged so as to be opposed to a partner side coil unit; and a columnar reinforcement member arranged between the second cover member 60 and the coil case 80.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a coil unit that is installed on the ground or in an electric vehicle in a contactless charging system that charges a battery mounted on the electric vehicle. [Background technology]

[0002] In recent years, contactless charging systems have been attracting attention as a method for charging the onboard batteries of electric vehicles. In contactless charging systems, power is transmitted between a power-transmitting coil unit installed on the ground and a power-receiving coil unit installed in the electric vehicle, thereby charging the battery installed in the electric vehicle.

[0003] Coil units used in contactless charging systems must be strong enough to withstand vehicle run-overs when placed on the ground, and strong enough to withstand collisions with obstacles protruding from the road surface and flying stones when placed underneath the vehicle. Furthermore, reducing the height of the coil unit is desirable to reduce contact with these obstacles. Meanwhile, in order to avoid interfering with the magnetic field generated between the coils, the coil unit case cannot be made of materials that are easy to ensure strength, such as metal, for the parts that cover the coils.

[0004] For example, in the coil unit (transmission device) described in Patent Document 1, a plate-shaped coil case (bobbin) is placed above a base plate placed on the ground, and a power transmission coil is fitted into the coil groove of the coil case. A resin cover member that covers the surface of the power transmission coil is placed above the coil case. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-126596 Summary of the Invention [Problem to be solved by the invention]

[0006] When the coil surface is covered with a resin cover member, as in the technology described in Patent Document 1, the thickness of the cover member increases to ensure strength, which poses a problem in that it is difficult to reduce the height of the device.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a coil unit for use in a contactless charging system that can improve the strength of the device case and achieve a low profile. [Means for solving the problem]

[0008] The coil unit of the present invention is a coil unit that is placed on the ground or on an electric vehicle in a contactless charging system that transmits power between a power transmitting coil unit placed on the ground and a power receiving coil unit placed on an electric vehicle, and charges a battery installed in the electric vehicle, and is provided with a flat coil case, a coil that is arranged in a spiral shape on the surface of the coil case, a cover member that covers the coil and is arranged to face the opposing coil unit, and a columnar reinforcing member that is placed between the cover member and the coil case. [Effects of the Invention]

[0009] The coil unit according to the present invention includes a flat coil case and a spiral coil disposed on the surface of the coil case, the coil being covered by a cover member disposed opposite the mating coil unit. A columnar reinforcing member is disposed between the coil case and the cover member, and a load applied to the cover member is transmitted through the reinforcing member and dispersed to the coil case. This allows the necessary strength to be maintained even if the cover member is made thin, thereby improving the strength of the device case and reducing its height. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a planar perspective view of the coil unit according to the embodiment. [Figure 2] FIG. 2 is a bottom perspective view of the coil unit according to the embodiment. [Figure 3] FIG. 2 is an exploded perspective view of the coil unit according to the embodiment. [Figure 4] (A) shows a perspective view of the top side of the case body, and (B) shows a perspective view of the bottom side of the case body. [Figure 5] FIG. 2 is a bottom view of the case body according to the embodiment. [Figure 6] 5A and 5B are partial cross-sectional views of the case body according to this embodiment, where (A) shows a cross-section taken along line VIA-VIA in FIG. 5, and (B) shows a cross-section taken along line VIB-VIB in FIG. 5. [Figure 7] 1A and 1B are perspective views showing a second cover member according to the present embodiment, in which (A) shows a top perspective view and (B) shows a bottom perspective view. [Figure 8] 10A and 10B are perspective views showing a third cover member according to the present embodiment, in which (A) is a perspective view from above and (B) is a perspective view from below. [Figure 9] 1A and 1B are perspective views showing a coil case according to this embodiment, in which (A) shows an exploded perspective view of the coil case as seen from the top side, and (B) shows a partially exploded perspective view of the coil case as seen from the bottom side. [Figure 10] 9A shows an exploded perspective view of the reinforcing plate and the sensor substrate housed in the second housing space, and FIG. 9B shows an enlarged view of an area P shown in FIG. 9A. [Figure 11] 1. FIG. 4 is a partial cross-sectional view showing a part of the second housing space according to the present embodiment, taken along line XI-XI in FIG. [Figure 12] 1 is a schematic diagram of a contactless charging system according to an embodiment of the present invention. [Figure 13] FIG. 2 is a block diagram showing a coil unit according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] A contactless charging system 100 according to an embodiment of the present invention and a coil unit 1 used in the contactless charging system 100 will be described below with reference to Figs. 1 to 13. In this embodiment, for convenience of explanation, the directions indicated by up-down, left-right, and front-rear arrows appropriately shown in each figure will be defined as the up-down direction, left-right direction, and front-rear direction, respectively. Also, in each figure, some reference numerals may be omitted to make the drawings easier to understand.

[0012] As shown in FIG. 12 , a contactless charging system 100 is a system for charging an electric vehicle 200, such as an electric vehicle or a plug-in hybrid vehicle. In the contactless charging system 100, power is transmitted between a power transmitting coil unit 1A disposed on the ground and a power receiving coil unit 1B disposed in the electric vehicle 200, thereby charging a battery 300 mounted on the electric vehicle 200. The power is transmitted by arranging a primary coil 2 housed in the power transmitting coil unit 1A and a secondary coil 2 housed in the power receiving coil unit 1B opposite each other, and transmitting power by utilizing electromagnetic induction between the coils. Specifically, AC power is supplied from a commercial power source 400 to the power transmitting coil unit 1A, causing an induced current to flow in the primary coil 2, generating a magnetic field. The generated magnetic field reaches the secondary coil 2, and an induced current flows in the secondary coil 2, thereby transmitting power.

[0013] In the following, the configuration will be described focusing on the power transmission coil unit 1A placed on the ground. When there is no need to distinguish between the power transmission coil unit 1A and the power receiving coil unit 1B, they will be simply referred to as coil unit 1.

[0014] 13 is a block diagram showing the main components of the power transmission coil unit 1A. As shown in this figure, the coil unit 1A has a coil 2, a power supply circuit unit 3, a power conversion unit 4, a control unit 5, and a sensor coil unit 6. The power supply circuit unit 3 generates control power to be supplied to the control unit 5 using AC power supplied from a commercial power source 400.

[0015] The power conversion unit 4 converts AC power supplied from the commercial power supply 400 into predetermined high-frequency AC power and supplies it to the power transmission coil 2. Specifically, the power conversion unit 4 has a PFC unit 4A and an inverter unit 4B. As an example, the PFC unit 4A is made up of a single-stage PFC (Power Factor Correction) circuit equipped with one converter, and converts AC power into DC power and improves the power factor of the power supply by shaping the output waveform. The inverter unit 4B is made up of an inverter circuit and converts the DC power supplied from the PFC unit 4A into high-frequency AC power and supplies it to the coil 2.

[0016] The control unit 5 has a function of generating various control signals for the coil unit 1A. Specifically, the control unit 5 has an impedance control unit 5A, a sensor control unit 5B, and a system monitoring control unit 5C. The impedance control unit 5A is composed of an IMN (Impedance Matching Network) circuit including multiple resonant chokes 41 (see FIG. 5) and multiple capacitors (not shown). The impedance control unit 5A matches the output impedance of the power transmitting side with the load impedance of the power receiving side based on the L value of the resonant chokes 41 and the C value of the capacitors, and controls the frequency of the high-frequency AC power output from the inverter unit 4B. This improves the power transmission efficiency between the coil units 1A and 1B. The sensor control unit 5B has a function of detecting foreign objects around the coil unit 1A. In this embodiment, the sensor control unit 5B controls the supply of current to the sensor coil unit 6 and is configured to be able to detect metallic foreign objects around the coil unit 1A based on a signal from the sensor coil unit 6. The system monitoring control unit 5C has a function of controlling monitoring within the wireless charging system 100.

[0017] In the coil unit 1A, the above-mentioned coil 2, power supply circuit section 3, power conversion section 4, control section 5, and sensor coil section 6 are housed in a device case 10. As shown in Figs. 1 to 3, the device case 10 has a case body 20 forming a housing, a first cover member 50 that closes the opening of the case body 20, and a second cover member 60 and a third cover member 70 that cover the surface of the case body 20.

[0018] (Case body) As shown in FIG. 4(A), the case body 20 forms a housing that is open on the installation surface side (the lower side in FIG. 4(A)), and has a front wall 20A, a rear wall 20B, a left wall 20C, a right wall 20D, and an upper wall 20E. The case body 20 has a predetermined width in the front-to-rear and left-to-right directions, and is formed flat in the up-to-down direction to have a low profile, allowing it to be installed with only a slight protrusion from the installation surface. As an example, the case body 20 is a die-cast member formed of a non-magnetic material such as aluminum.

[0019] The surface of the upper wall 20E of the case body 20 facing the mating coil unit 1 (1B) (the upper surface in FIG. 4(A)) has a flat front area FA and a rear area RA on which a plurality of heat dissipation fins 22 are integrally provided. The front area FA is an area covered by the second cover member 60 described later, and has an annular groove 24 provided on the joint surface with the second cover member 60, and a plurality of screw holes 26 provided along the groove 24. The rear area RA is an area covered by the third cover member 70 described later, and the plurality of heat dissipation fins 22 formed on the surface of the rear area RA are formed across the rear area RA, the rear wall 20B, the rear portion of the left wall 20C, and the rear portion of the right wall 20D.

[0020] As shown in FIG. 4(B), the inner surface of the upper wall portion 20E is formed with a plurality of cylindrical bosses 28 protruding toward the installation surface, and a plurality of circuit boards 40 (see FIG. 5) and a plurality of circuit components are fixed to the inner surface of the upper wall portion 20E via the plurality of bosses 28. Furthermore, a first partition wall portion 30 and a second partition wall portion 32 are erected on the inner surface of the upper wall portion 20E. The first partition wall portion 30 is composed of a first rib 301 extending in the front-rear direction through the center of the front of the upper wall portion 20E, and a second rib 302 extending in the left-right direction so as to intersect with the first rib 301. The second partition wall portion 32 is composed of a third rib 321 extending in the front-rear direction through the center of the rear of the upper wall portion 20E. These first and second partition wall portions 30, 32 divide the internal space of the case body 20 into multiple compartments and serve as jigs for positioning multiple circuit boards 40 (described later), as well as reinforcing members for increasing the rigidity of the case body 20.

[0021] FIG. 5 shows a bottom view of the case body 20. As shown in this figure, a plurality of bosses 34, 36 are integrally formed on the front wall 20A, rear wall 20B, left wall 20C, and right wall 20D that constitute the side walls of the case body 20. Screw members 98 (see FIG. 6) for fixing a first cover member 50 (described later) to the case body 20 are threadedly engaged with these bosses 34, 36. Specifically, the bosses 34 arranged on the front wall 20A, rear wall 20B, and rear portions of the left wall 20C and right wall 20D are integrally formed with the heat dissipation fins 22 protruding from the surface of the case body 20. Meanwhile, the bosses 36 arranged on the front portion of the left wall 20C and the right wall 20D are integrally formed between the outer and inner walls of the double-wall structure of the left wall 20C and right wall 20D.

[0022] In the case body 20 configured as described above, the internal space formed by the front wall 20A, rear wall 20B, left wall 20C, right wall 20D, and top wall 20E is a first housing space S1. Six circuit boards 40 (A to F) that constitute the power supply circuit section 3, power conversion section 4, and control section 5 of the coil unit 1A are housed in this first housing space S1.

[0023] The rear space of the first housing space S1 accommodates circuit boards 40A to 40C. The circuit boards 40A to 40C are circuit boards that constitute the power supply circuit unit 3 and the power conversion unit 4. Specifically, the power supply circuit that constitutes the power supply circuit unit 3 is mounted on the circuit board 40A, the PFC circuit that constitutes the PFC unit 4A of the power conversion unit 4 is mounted on the circuit board 40B, and the inverter circuit that constitutes the inverter unit 4B of the power conversion unit 4 is mounted on the circuit board 40C. These circuit boards 40 are portions through which a large current flows when the coil unit 1A is operating, and are circuit boards that generate a large amount of heat. In particular, the PFC circuit and the inverter circuit that constitute the power conversion unit 4 have multiple switching elements 42 (see FIG. 6(B)), and therefore the amount of heat generated by the switching elements 42 when current is applied increases the amount of heat generated by the circuit boards. Therefore, these circuit boards 40A to 40C that generate a large amount of heat are accommodated in the rear part of the first accommodation space S1 and are arranged opposite the inner surface of the part of the upper wall part 20E where the heat dissipation fins 22 are formed. This allows the heat generated by the circuit boards 40A to 40C to be dissipated to the outside of the case body 20 efficiently.

[0024] Meanwhile, the front space of the first housing space S1 accommodates circuit boards 40D to 40F. The circuit boards 40D to 40F are circuit boards that constitute the control unit 5. Specifically, an IMN circuit that constitutes the impedance control unit 5A is mounted on the circuit board 40D, a control circuit that constitutes the sensor control unit 5B is mounted on the circuit board 40E, and a control circuit that constitutes the system monitoring control unit 5C is mounted on the circuit board 40F.

[0025] As described above, the upper wall portion 20E has a plurality of bosses 28 on its inner surface, and the plurality of circuit boards 40A-40F are supported on the inner surface via the bosses 28. As an example, FIG. 6A shows a cross section of a circuit board 40C that constitutes the inverter unit 4B. As shown in this figure, the circuit boards 40A-40F are fixed by inserting screw members 98 into through holes formed in the boards and threading the male threads of the screw members 98 into the female threads formed on the inner surface of the bosses 28. This positions the circuit boards 40A-40F closely facing the upper wall portion 20E.

[0026] Here, the circuit boards 40B and 40C further have heat transfer paths for directly dissipating heat generated by the switching elements 42 toward the case body 20. FIG. 6B shows a cross section of the circuit board 40C constituting the inverter unit 4B as an example. As shown in this figure, the switching elements 42 mounted on the circuit board 40C are disposed between the upper wall portion 20E of the case body 20 and the circuit board 40C. The switching elements 42 have a main body portion 421 molded with insulating resin and lead portions 422 extending from the main body portion 421, with the tips of the lead portions 422 electrically connected to a wiring pattern formed on the board. In this switching element 42, the resin-molded main body portion 421 is disposed so as to abut against the inner surface of the upper wall portion 20E via the insulating sheet 43. This provides a heat dissipation path for directly transferring heat generated in the main body portion 421 to the upper wall portion 20E. Furthermore, one end of a bracket-shaped heat dissipation member 44 extending from the upper wall portion 20E toward the switching element 42 is fixed to the inner surface of the upper wall portion 20E, providing a heat dissipation path for transferring heat generated in the main body 421 of the switching element 42 to the upper wall portion 20E via the heat dissipation member 44. The heat dissipation member 44 is made of, for example, a metal plate with excellent thermal conductivity, and one end of the heat dissipation member 44 in the extending direction is fixed to the upper wall portion 20E with a screw member 98. The screw member 98 is threadedly engaged with a boss portion 46 provided on the upper wall portion 20E. The boss portion 46 protrudes upward from the upper wall portion 20E and is formed integrally with the heat dissipation fins 22. This allows heat transferred to the heat dissipation member 44 to be efficiently transferred to the heat dissipation fins 22 and dissipated to the outside of the case body 20.

[0027] Furthermore, the six circuit boards 40A-40F are housed inside a housing formed by the case body 20 made of a non-magnetic material and the first cover member 50 (described later), thereby protecting them from heat generation due to electromagnetic induction by the coil 2. That is, the non-magnetic material that forms the case body 20 and the first cover member 50 is hardly magnetized by an external magnetic field. Therefore, compared to a housing made of a ferromagnetic material such as steel, induction heating due to electromagnetic induction by the coil 2 can be suppressed, and the circuit boards 40A-40F housed in the first housing space S1 can be protected from heat generation by the case body 20.

[0028] (First cover member) 3, a rectangular plate-shaped first cover member 50 is disposed on the installation surface side (the lower side in FIG. 3) of the case body 20, and the opening of the case body 20 is closed by the first cover member 50. The first cover member 50 is a rectangular plate-shaped member made of a non-magnetic material such as aluminum, just like the case body 20.

[0029] 2 and 6(A), a plurality of through holes 52 that penetrate the first cover member 50 in the up-down direction are formed on the outer periphery of the first cover member 50. The first cover member 50 is fixed to the case body 20 by inserting screw members 98 into the through holes 52 and threading the male threads of the screw members 98 into the female threads of bosses 34, 36 provided on the side walls (front wall 20A, rear wall 20B, left wall 20C, and right wall 20D) of the case body 20. The screw members 98 that join the case body 20 and the first cover member 50 are arranged facing the installation surface when the coil unit 1A is installed, and are therefore not exposed to the outside.

[0030] (Second cover member) As shown in FIGS. 1 and 3, a flat front area FA of the upper wall portion 20E of the case body 20 is covered with a second cover member 60. The second cover member 60 is formed of a resin material, for example. As shown in FIGS. 7(A) and 7(B), the second cover member 60 forms a housing that opens toward the case body 20 (the downward side in FIG. 7), and forms a second housing space S2 between the second cover member 60 and the upper wall portion 20E of the case body 20 to house the coil 2 and the like. Specifically, the second cover member 60 has a ceiling wall portion 62 facing the upper wall portion 20E of the case body 20, a side wall portion 64 hanging down from the outer peripheral edge of the ceiling wall portion 62, and a brim-shaped flange portion 66 provided at the end of the side wall portion 64. The second cover member 60 is fixed to the case body 20 by screwing the flange portion 66 to the upper wall portion 20E of the case body 20.

[0031] 7(B), a sealant 69 is interposed between the flange portion 66 of the second cover member 60 and the upper wall portion 20E of the case body 20. The sealant 69 is, for example, a silicone-based wet sealant that is filled in a liquid state into the recessed groove 24 of the case body 20 and becomes an elastic rubber-like material when hardened.

[0032] The lower surface of the flange 66 (the surface facing the upper wall 20E of the case body 20) is formed with an annular protrusion 67 extending along the outer periphery of the second cover member 60 and a plurality of notches 68 arranged along the protrusion 67. When the second cover member 60 is installed on the upper wall 20E of the case body 20, the protrusion 67 is inserted into the recessed groove 24 formed in the surface of the upper wall 20E. In this state, a predetermined gap is formed between the side surface of the recessed groove 24 and the protrusion 67, and an elastic sealant 69 is filled in the gap, resulting in the sealant 69 being interposed between the side surface of the recessed groove 24 and the protrusion 67. The elastic deformation of the sealant 69 absorbs misalignment of the joining surfaces caused by the difference in linear expansion and contraction between the metal case body 20 and the resin second cover member 60. Furthermore, by inserting the convex portion 67 into the concave groove 24, the bonding area via the sealing material 69 can be set larger compared to bonding between flat surfaces, thereby increasing the bonding strength between the flange portion 66 and the case body 20.

[0033] The second cover member 60 has an inclined surface 64A formed by chamfering the corners on the inner surface of the side wall portion 64. The inclined surface 64A is inclined so that the gap between the surface of the upper wall portion 20E increases toward the inside of the second cover member 60. Therefore, excess sealing material 69 extruded from the recessed groove 24 remains between the inclined surface 64A and the upper wall portion 20E, forming a thick sealing layer and not flowing into the interior of the second cover member 60. This makes it possible to prevent contact between the sealing material 69 and components housed inside the second cover member 60. Furthermore, the thick sealing layer formed by the excess sealing material 69 enhances the airtightness of the interior of the second cover member 60.

[0034] In this way, the flange portion 66 of the second cover member 60 is tightly attached to the upper wall portion 20E of the case body 20 by the wet sealant 69. Thereafter, the screw member 98 is inserted into the notch portion 68 of the flange portion 66, and the male thread portion of the screw member 98 is screwed into the female thread portion of the screw hole 26 formed in the case body 20, thereby fixing the second cover member 60.

[0035] (Third cover member) 1 and 3, the rear area RA of the upper wall portion 20E of the case body 20, where the heat dissipation fins 22 are formed, is covered with a third cover member 70. This third cover member 70 is a protective cover made of a resin material, and is provided to reduce the risk of a user coming into contact with the high-temperature heat dissipation fins 22.

[0036] 8(A) and 8(B), the third cover member 70 forms a housing that opens toward the case body 20 (the lower side in FIG. 8), and is fixed to the case body 20 at multiple locations on its outer periphery with fasteners such as screws (not shown). The third cover member 70 is a mesh-like cover member with multiple elongated through-holes 71 formed across its entire surface. Therefore, the third cover member 70 has excellent ventilation between the inside and outside, and can efficiently release heat emitted from the heat dissipation fins 22 into the outside air, so heat dissipation performance is not impaired.

[0037] 8(B), the third cover member 70 has a ceiling wall portion 72 that faces the surface of the case body 20 (the surface facing the mating coil unit 1B), and a cover reinforcing portion 74 is integrally provided on the inner surface of the ceiling wall portion 72. The cover reinforcing portion 74 has a plurality of protrusions 741 that protrude from the inner surface of the ceiling wall portion 72 toward the case body 20, and when the third cover member 70 is fixed to the case body 20, each of the protrusions 741 is positioned between the heat dissipation fins 22. As a result, the third cover member 70 is supported and reinforced by the case body 20 from the inside via the protrusions 741.

[0038] As shown in Figure 3, the second storage space S2 formed between the case body 20 and the second cover member 60 accommodates an auxiliary shielding plate 76, a ferrite plate 78, a coil case 80, a coil 2, a reinforcing plate 88, and a sensor board 94.

[0039] The auxiliary shielding plate 76 is a rectangular plate-like member having a predetermined width in the front-rear and left-right directions and a predetermined thickness in the up-down direction, and is arranged to cover the front area FA of the case main body 20. The auxiliary shielding plate 76 is made of a non-magnetic material such as aluminum, just like the case main body 20, and is arranged to shield the case main body 20 from the magnetism generated by the coil 2.

[0040] A flat coil case 80 is disposed above the auxiliary shielding plate 76. As shown in FIG. 9, the coil case 80 is a rectangular, resin-made, plate-like member having a predetermined width in the front-rear and left-right directions and a predetermined thickness in the up-down direction. A spiral-shaped coil groove 82 is formed on one surface (the upper surface in FIG. 9) of the coil case 80, and a coil 2 formed in a spiral shape is disposed inside the coil groove 82. The linear conductor constituting the coil 2 is, for example, a Litz wire. A Litz wire is formed by twisting together a plurality of wires (thin wires) with an insulating coating, and is excellent in suppressing winding resistance due to the skin effect. Lead wires 2A and 2B (see FIG. 9(A)) drawn from both ends of the coil 2 pass through coil insertion portions 84A and 84B formed by penetrating the center and ends of the coil case 80, and are electrically connected to a plurality of circuit boards 40A to 40F inside the case main body 20.

[0041] As shown in Fig. 9(B), the other surface of the coil case 80 (the lower surface in Fig. 9) has a plurality of compartments separated in a grid pattern by a plurality of partition walls 86. A plurality of rectangular ferrite plates 78 are fixed to each of the compartments.

[0042] A reinforcing plate 88 is disposed above the coil case 80, and two sensor boards 94 are disposed side by side in the left-right direction above the reinforcing plate 88. The reinforcing plate 88 is a rectangular plate-shaped member made of resin, having a predetermined width in the front-rear and left-right directions and a predetermined thickness in the up-down direction. The reinforcing plate 88 has a plurality of reinforcing members 90 integrally formed therewith. Each of the reinforcing members 90 has a cylindrical outer wall 901 and a lattice-shaped lattice rib 902 integrally formed on the inside thereof, forming a columnar shape. The reinforcing members 90 are regularly arranged on the upper surface of the reinforcing plate 88 and are inserted into a plurality of through holes 96 formed through the sensor board 94. Therefore, as shown in FIG. 11 , the reinforcing members 90 are disposed between the coil case 80 and the second cover member 60, and the upper wall portion 20E of the second cover member 60 is supported from below by the reinforcing members 90.

[0043] The reinforcing plate 88 also has a plurality of board support portions 92 that protrude from the upper surface of the reinforcing plate 88 toward the second cover member 60. Each of the plurality of board support portions 92 is formed in a cylindrical shape with a smaller diameter than the reinforcing member 90, and is regularly arranged on the upper surface of the reinforcing plate 88. The plurality of board support portions 92 support two sensor boards 94 from below at positions spaced apart from the reinforcing plate 88. The two sensor boards 94 and the board support portions 92 are fixed to each other using resin clips (not shown).

[0044] The two sensor substrates 94 are, for example, configured by wiring substrates having a plurality of sensor coil units 6 for metal detection. The plurality of through holes 96 formed in the two sensor substrates 94 are provided so as to penetrate the center of each sensor coil unit 6.

[0045] FIG. 10B is an enlarged view of region P in FIG. 10A. As shown in this figure, the sensor coil unit 6 is composed of a pair of coils 61 and 62 formed on the upper and lower surfaces of the sensor substrate 94. As described above, the sensor coil unit 6 is electrically connected to the sensor control unit 5B mounted on the circuit board 40E. The sensor control unit 5B controls AC power to supply AC power to the primary coil 6A formed on the lower surface of the sensor substrate 94. When AC power is supplied to the primary coil 6A, an induced electromotive force is generated in the secondary coil 6B disposed on the upper surface of the sensor substrate 94 due to a magnetic field formed around the primary coil 6A. If a metallic foreign object is present around the sensor coil unit 6, the magnetic flux of the primary coil 6A flows through the metallic foreign object, causing an overcurrent to flow through the metallic foreign object. This increases the effective resistance of the secondary coil 6B, and the induced electromotive force of the secondary coil 6B fluctuates relative to the set value. Therefore, the presence or absence of metallic foreign matter can be determined by detecting the voltage across secondary coil 6B with sensor control unit 5B. This method of detecting metallic foreign matter using a pair of coils 61, 62 is publicly known, as disclosed in JP 2017-126596 A, and therefore a detailed description thereof will be omitted.

[0046] Before transmitting power from the coil 2, the sensor control unit 5B energizes the multiple sensor coil units 6 to determine whether or not a metallic foreign object is present on the second cover member 60. If a metallic foreign object is present on the second cover member 60, the supply of power to the coil 2 is stopped because there is a risk that the metallic foreign object will become hot due to the magnetic flux around the coil 2.

[0047] (Action and effect) As described above, in the coil unit 1 of this embodiment, the coil 2 formed in a spiral shape and multiple circuit boards 40 (A to F) electrically connected to the coil 2 are housed in the device case 10. This device case 10 has a case main body 20 forming a housing with an opening on the installation surface side, and the multiple circuit boards 40 are housed in a first housing space S1 of the case main body 20, and the opening on the installation surface side is closed by a first cover member 50. In addition, the case main body 20 forms a second housing space S2 between a surface facing the mating coil unit 1 and a second cover member 60 covering this surface, and the coil 2 is housed in the second housing space S2. Therefore, since an opening of the case main body 20 is not formed on the surface facing the mating coil unit 1, the strength of the case main body 20, and therefore the strength of the device case 10, can be improved.

[0048] Furthermore, the second cover member 60 is configured to cover a portion of the surface of the case body 20, and the accommodation surface of the first accommodation space S1 is set larger than the accommodation surface of the second accommodation space S2. This allows the case body 20 to be made smaller in the height direction while ensuring accommodation space for multiple circuit boards 40, thereby enabling the device case 10 to be made thinner.

[0049] Furthermore, in this embodiment, a plurality of heat dissipation fins 22 are integrally formed on the surface of the case body 20 in a portion where the second cover member 60 is not disposed. This improves the heat dissipation performance of the case body 20, which dissipates heat generated inside the case body 20 to the outside, and can protect the plurality of circuit boards 40 disposed in the first housing space S1 from heat generation when current is applied.

[0050] Furthermore, in this embodiment, of the multiple circuit boards 40A to 40F housed in the case body 20, the circuit boards 40A to 40C that generate a large amount of heat are supported on the inner surface of the portion of the case body 20 where the multiple heat dissipation fins 22 are formed. This allows the heat generated by the circuit boards 40A to 40C that generate a large amount of heat to be efficiently transferred to the heat dissipation fins 22, thereby improving the heat dissipation efficiency of the case body 20.

[0051] Furthermore, the multiple circuit boards 40A to 40F are covered with a case body 20 and a first cover member 50 made of a non-magnetic material. Therefore, when power is transmitted between the coil unit 1, the case body 20 and the first cover member 50 are hardly magnetized by the magnetic field of the coil 2. Therefore, compared to a housing made of a ferromagnetic material such as steel, induction heating of the case body 20 and the first cover member 50 due to the electromagnetic induction action of the coil 2 can be suppressed, and the circuit boards 40A to 40F housed in the first housing space S1 can be protected from heat generated by the case body 20 and the like.

[0052] Furthermore, in this embodiment, the coil 2 constituting the coil unit 1 is formed in a spiral shape and arranged on the surface of a flat coil case 80. The coil 2 is covered by a second cover member 60 arranged to face the mating coil unit 1. Here, a columnar reinforcing member 90 is arranged between the coil case 80 and the second cover member 60, so that the load input to the second cover member 60 is dispersed to the coil case 80 side via the reinforcing member 90. This ensures that the necessary strength can be ensured even if the plate thickness of the second cover member is thin, and therefore the strength of the device case 10 can be improved and the height can be reduced.

[0053] Here, the reinforcing member 90 is provided integrally with a reinforcing plate 88 disposed between the coil case 80 and the second cover member 60 so as to protrude toward the second cover member 60. As a result, the load input to the second cover member 60 is distributed to the plate-shaped reinforcing plate 88 via the columnar reinforcing member 90, so that even if the contact area between the second cover member 60 and an obstacle is small, localized concentration of the load is suppressed. In this way, the efficiency of distribution of the load transmitted to the reinforcing member 90 can be increased, and the strength of the device case 10 can be effectively improved.

[0054] Furthermore, in this embodiment, a sensor board 94 is provided between the coil case 80 and the second cover member 60, and the reinforcing member 90 is disposed between the coil case 80 and the second cover member 60 while being inserted into a through hole 96 formed in the sensor board 94. This increases the strength of the device case, and makes it possible to accommodate the sensor board 94 by utilizing the space formed between the coil case 80 and the second cover member 60.

[0055] Furthermore, in this embodiment, the sensor substrate 94 has a plurality of sensor coil units 6 formed on one plane of the sensor substrate 94, and the plurality of through holes 96 are formed so as to penetrate the central parts of the sensor coil units 6. As a result, in the sensor substrate 94 having the sensor coil units 6, the central parts of the sensor coil units 6, which would otherwise be dead space, can be used to place the reinforcing member 90, minimizing restrictions on the board design of the sensor substrate 94 and increasing the strength of the device case 10.

[0056] Furthermore, the sensor board 94 is disposed between the reinforcing plate 88 and the second cover member 60, and is supported by a plurality of board support portions 92 that protrude from the reinforcing plate 88 toward the sensor board 94. This allows the sensor board 94 to be disposed at a position separated from the reinforcing plate 88, allowing a large distance to be set between the coil 2 disposed in the coil case 80 and the sensor board 94. This reduces the magnetic effect that the magnetic field of the coil 2 has on the sensor board 94 during power reception or power transmission, and prevents fluctuations in sensing accuracy.

[0057] [supplementary explanation] In the above embodiment, the explanation has been centered on the power transmission coil unit 1A that is placed on the ground, but the configuration of the present invention can also be applied to the power reception coil unit 1B that is placed on the vehicle side.

[0058] Furthermore, in the above embodiment, the columnar reinforcing member 90 disposed between the coil case 80 and the second cover member 60 is configured to be integrally formed with the reinforcing plate 88, but the present invention is not limited to this. For example, the reinforcing member 90 may be configured to be integrally formed with the second cover member 60 so as to protrude from the second cover member 60 toward the coil case 80. By providing the reinforcing member 90 integrally with the cover member 60, the number of parts required during assembly can be reduced, and the manufacturing process can be simplified.

[0059] In the above embodiment, the sensor coil unit 6 is formed on the surface (top and bottom surfaces) of the sensor substrate 94 as the "sensor coil unit formed on one plane of the sensor substrate," but "on one plane of the sensor substrate" is a broad concept that includes an internal plane of the sensor substrate and is not limited to the configuration of the above embodiment. That is, the sensor coil unit 6 may be formed on one internal plane of the sensor substrate 94. [Explanation of symbols]

[0060] 1 coil unit (1A, 1B) 2 coils 6 Sensor coil section 60 second cover member (cover member) 80 coil case 88 Reinforcement plate 90 Reinforcement member 92 Substrate support 94 Sensor board 96 through holes 100 Wireless charging system 200 electric vehicles 300 Battery

Claims

1. A coil unit disposed on the ground or on an electric vehicle in a contactless charging system that transmits power between a power transmission side coil unit disposed on the ground and a power receiving side coil unit disposed on an electric vehicle and charges a battery mounted on the electric vehicle, A flat coil case, a coil arranged in a spiral shape in a coil groove formed on a surface of the coil case; a cover member that covers the coil and is arranged to face the other coil unit; a columnar reinforcing member disposed between the cover member and the coil case; a reinforcing plate disposed between the coil case and the cover member, The reinforcing member is integrally provided on the reinforcing plate so as to protrude from the reinforcing plate toward the cover member.

2. A plurality of the reinforcing members are provided, 2. The coil unit according to claim 1, wherein each of the plurality of reinforcing members has a cylindrical outer wall and a lattice-shaped lattice rib integrally formed on the inside of the wall, forming a columnar shape.

3. The coil unit according to claim 1 , wherein the reinforcing member is integrally provided with the cover member so as to protrude from the cover member toward the coil case.

4. a sensor substrate disposed between the coil case and the cover member, 4. The coil unit according to claim 1, wherein the reinforcing member is disposed in a state where it is inserted into a through hole formed in the sensor substrate.

5. the sensor substrate has a plurality of sensor coil units formed on one plane of the sensor substrate, The coil unit according to claim 4 , wherein the through hole penetrates a central portion of the sensor coil unit.

6. a reinforcing plate disposed between the coil case and the cover member; a sensor substrate disposed between the reinforcing plate and the cover member, The coil unit according to any one of claims 1 to 5, wherein the reinforcing plate has a substrate support portion that protrudes toward the sensor substrate and supports the sensor substrate at a position spaced apart from the reinforcing plate.

Images