JP7728162B2 - Power transmission device and power supply system - Google Patents

Description

Embodiments of the present invention relate to a power transmission device and a power supply system.

Power supply systems that transmit and receive power contactlessly have been known for some time. In such power supply systems, if a metallic foreign object is present between the power transmission coil of the power transmission device and the power receiving coil of the power receiving device, the metallic foreign object generates heat. If the metallic foreign object is equal to or larger than a predetermined size, it can be detected by detecting changes in the value of the current flowing through the power transmission circuit, etc. However, if the metallic foreign object is smaller than the predetermined size, the change in the current value caused by the metallic foreign object is small, making it difficult to detect the metallic foreign object.

For example, one known technique is to detect heat generated by metallic foreign objects by providing a heat-sensing unit in the power transmission device and detecting the temperature. However, this technique may not be able to accurately detect the temperature unless the heat from the heated metallic foreign object is transferred to the heat-sensing unit.

For example, when a metallic foreign object made of metal foil or metal plate is placed on the winding of a power transmission coil, a large metallic foreign object will raise the temperature of the winding through thermal conduction. This is detected by the heat-sensing part of the temperature sensor, allowing the foreign object to be detected.

On the other hand, with small metal foreign objects, the contact area with the winding or heat-sensing part is small, which can inhibit heat transfer. As a result, even if the temperature of the metal foreign object itself rises, the heat-sensing part cannot detect this temperature increase, and there is a risk that power will be transmitted from the power transmission device while the temperature remains elevated.

Japanese Patent Application Laid-Open No. 2012-182258

The problem that this invention aims to solve is to provide a power transmission device and power supply system that can suppress temperature increases in metallic foreign objects.

The power transmission device of this embodiment includes a power transmission coil, a casing, and a fan. The power transmission coil has gaps formed between adjacent windings. The power transmission coil is provided on the top wall of the casing facing the power receiving device, and an exhaust port is formed in the top wall facing the gap in the power transmission coil. The fan is provided within the casing.

FIG. 1 is a perspective view showing a configuration of a power supply system according to an embodiment. FIG. 1 is a perspective view showing a configuration of a cart used in a power supply system according to an embodiment. FIG. 2 is a block diagram showing the configuration of a control system of the power supply system according to the embodiment. FIG. 2 is a top view showing the configuration of a power transmission device of the power supply system according to the embodiment. 1 is a cross-sectional view schematically illustrating the configuration of a power receiving device and a power transmitting device of a power supply system according to an embodiment. FIG. 2 is a plan view schematically illustrating a configuration of a first example of a power transmission coil and a magnetic body of a power transmission device according to an embodiment. FIG. 2 is a plan view schematically illustrating a configuration of a first example of a power transmitting coil of a power transmitting device according to an embodiment. FIG. 2 is a plan view schematically illustrating a configuration of a first example of a magnetic body of a power transmitting device according to an embodiment. FIG. 10 is a plan view schematically showing a configuration of a second example of a power transmitting coil and a magnetic body of a power transmitting device according to an embodiment.

The power supply system according to the first embodiment will be described below with reference to FIGS. 1 to 9. FIG. 1 is a perspective view showing the configuration of the power supply system according to the first embodiment, and FIG. 2 is a perspective view of a cart for the power supply system. FIG. 3 is a block diagram showing the configuration of the control system of the power supply system. FIG. 4 is a top view showing the configuration of the power transmission device 35 of the power supply system 1, and FIG. 5 is a cross-sectional view schematically showing the configuration of the power receiving device 23 and power transmission device 35 of the power supply system 1. FIGS. 6 to 9 are plan views schematically showing examples of the power transmission coil 351 and magnetic material 355.

As shown in Figures 1 and 3, the power supply system 1 includes a power receiving device 23 and a power transmitting device 35. The power receiving device 23 is provided, for example, on a cart 2. A plurality of power transmitting devices 35 are provided, for example, on a cart base 3 that houses a plurality of carts 2, along the direction of travel of the carts 2. In the following description of the embodiment, an example of the power supply system 1 in which the power receiving device 23 and the power transmitting device 35 are applied to the cart 2 and the cart base 3 will be described.

As shown in FIG. 1, the power supply system 1 includes a cart 2 equipped with a power receiving device 23, and a cart base 3 on which multiple carts 2 are installed and which is equipped with a power transmitting device 35. In the power supply system 1, multiple carts 2, each equipped with a power receiving device 23, are stored in a line on the cart base 3 which has multiple power transmitting devices 35 arranged in a line, and the multiple power transmitting devices 35 and multiple power receiving devices 23 are arranged facing each other at a predetermined interval.

The cart 2 shown in Figures 1 and 2 is a mobile object, such as a shopping cart. The cart 2 includes a frame 11, a basket section 12, casters 151 and 152, electronic equipment 21, a battery box 223 with a battery 22 installed inside, and a power receiving device 23.

The frame 11 is composed of multiple frame members that extend in different directions. The frame 11 supports the car section 12, multiple casters 151, 152, various electronic devices 21, and power receiving device 23 at their respective designated locations.

The frame 11 includes, for example, a pair of left and right vertical frame portions 111, a lower frame portion 112, a horizontal frame portion 113, a handle portion 114, and an attachment frame 115. The vertical frame portions 111, the lower frame portion 112, and the horizontal frame portions 113 extend in directions that intersect with each other.

The vertical frame section 111 comprises a pair of main frames 1111 extending upward from the rear casters 152, a pair of sub-frames 1112 provided on the rear side of the main frames 1111, and a pair of sub-frames 1113 provided on the front side of the main frames 1111. The vertical frame section 111 extends vertically behind the car section 12, and the rear casters 152 are located at the lower end.

The lower frame section 112 comprises multiple frame members arranged along the floor surface. The lower frame section 112 comprises, for example, a pair of main frames 1121, a support frame 1123, a front connecting section 1124, and an attachment section 1125 provided below the support frame 1123. The main frame 1121 extends forward from the rear caster 152 toward the front caster 151.

The support frame 1123 is a frame member that extends downward from the horizontal frame portion 113, bends forward at a predetermined height, extends forward, and has a front end that bends upward. The support frame 1123 is, for example, a U-shaped frame member that curves and folds back at the front. The support frame 1123 extends along a plane parallel to the floor inside the main frame 1121. The support frame 1123 forms a basket storage area on its upper side.

The front connecting portion 1124 extends widthwise at the front end of the lower end of the cart 2 and connects the front ends of the pair of main frames 1121.

The upper end of the mounting portion 1125 is fixed to a predetermined position on the support frame 1123. The mounting portion 1125 extends downward from the support frame 1123, bends backward at a predetermined height, and continues extending rearward. The mounting portion 1125 is a frame member to which the power receiving device 23 is attached. The mounting portion 1125 extends along a plane parallel to the floor inside the main frame 1121, and forms a support surface that supports the power receiving device 23 on the underside of the support frame 1123. For example, the mounting portion 1125 is sized so that when the cart 2 is installed on the cart base 3, the power transmitting device 35 provided on the cart base 3 and the power receiving device 23 provided on the mounting portion 1125 are positioned opposite each other with a predetermined distance between them.

The horizontal frame section 113 has multiple link frames 1131, 1132, and 1133 that span the width between the left and right vertical frame sections 111.

The handle portion 114 is located above the rear end of the cart 2. The handle portion 114 is arranged contiguous with the upper end of the vertical frame portion 111. For example, the handle portion 114 extends in the width direction.

The mounting frame 115 is connected to the vertical frame portion 111. The mounting frame 115 extends, for example, above one of the vertical frame portions 111 and supports various electronic devices 21.

In the frame 11, the car section 12 is supported on the vertical frame section 111, and a front caster 151 and a rear caster 152 are provided at the front and rear ends, respectively, of the lower frame section 112, which is disposed below the car section 12. In addition, in the frame 11, a power receiving device 23 is provided on a mounting section 1125, which is a frame member disposed along the floor surface, of the lower frame section 112. Furthermore, a battery box 223 is provided on the vertical frame section 111. For example, the battery box 223 is supported on a pair of sub-frames 1112 of the vertical frame section 111.

Furthermore, the pair of main frames 1121 in the lower frame section 112 extend diagonally toward the center at the front so that the widthwise spacing at the front is narrow. Therefore, the frame 11 is formed so that the width at the front is narrow and the width at the rear is wide in the forward direction of the cart 2.

The car section 12 is configured in the shape of a box that opens upward, for example, using perforated panel members or mesh wire members. The car section 12 is positioned in front of the vertical frame section 111, at a height spaced above the floor. The left and right sides of the rear end of the car section 12 are supported by the vertical frame section 111.

The front caster 151 and rear caster 152 each have a wheel 153 that rotates in the direction of travel, and a bracket portion 154 that rotatably supports the wheel 153. The bracket portion 154 is rotatably attached to the frame 11. The cart 2 moves when the wheel 153 of the caster 15 rotates on the floor surface. In addition, the traveling direction of the cart 2 can be changed by rotating the bracket portion 154 of the caster 15.

Similar to the shape of the frame 11 and basket section 12, the front casters 151 at the front are positioned so that their width from side to side is narrower than the rear casters 152 at the rear. Therefore, when storing multiple carts 2 lined up one behind the other, the carts 2 can be stored so that the frame 11 of the rear cart 2 overlaps the frame 11 of the front cart 2.

Electronic device 21 is an information terminal such as a tablet terminal for providing information to the user, or a product reader for obtaining information on products selected by the user. Electronic device 21 is connected to, for example, battery 22, and is powered by power from battery 22. Electronic device 21 may also be a charging device for charging a mobile device (e.g., a mobile phone, smartphone, digital camera, etc.) carried by the user using power from battery 22.

In this embodiment, an example is shown in which the electronic device 21 includes a tablet terminal 211 and a product reader 212. The tablet terminal 211 is a computer with a display unit equipped with a touch panel. The tablet terminal 211 is installed with its display unit facing the user positioned on the handle unit 114 side. The tablet terminal 211 displays, for example, information about products read by the product reader 212. The tablet terminal 211 may also perform payment processing for products read by the product reader 212.

The product reader 212 is a device that reads product information. The product reader 212 may also have a display unit that displays the read product information. The product reader 212 is, for example, an RFID tag reader that reads RFID tags attached to products being placed in or taken out of the basket unit 12. The product reader 212 may also be a scanner that reads product identification information, such as barcodes, attached to products.

In addition, the electronic device 21 may be an interface device for connecting a mobile device (smartphone, tablet device, etc.) owned by the user instead of the tablet device 211. The mobile device connected to the interface device as the electronic device 21 may perform the same processing as the tablet device 211 described above. In addition, the interface device as the electronic device 21 may charge the battery equipped in the mobile device. In addition, the interface device as the electronic device 21 may have a built-in battery 22, or may be connected to a separately provided battery 22.

The battery box 223 is provided on the frame 11. The battery box 223 is fixed to and supported by, for example, a pair of sub-frames 1112 arranged below the opening/closing panel 121 of the car section 12. The battery 22 is a power supply device that supplies power to the electronic devices 21 mounted on the cart 2, and includes a charging circuit 221 and a battery pack 222. The battery 22 is connected to and charged by the power receiving device 23.

The charging circuit 221 supplies the power supplied from the load circuit 2325 of the power receiving device 23 to the battery pack 222 as charging power (charging power). For example, the charging circuit 221 converts the power supplied from the load circuit 2325 into direct current (charging power) used to charge the battery pack 222. In other words, the charging circuit 221 converts the power from the load circuit 2325 into charging power of a predetermined current value and voltage value for charging the battery pack 222 and supplies it to the battery pack 222. The charging circuit 221 charges the battery pack 222 with power from the power receiving device 23.

The battery pack 222 is charged by the charging power supplied from the charging circuit 221. The battery pack 222 is also connected to the electronic device 21 and supplies power to the electronic device 21.

The power receiving device 23 receives power transmitted contactlessly and supplies the received power to the electronic device 21 or the battery 22. The power receiving device 23 may also be configured to include an output terminal that supplies power to the electronic device 21. In this case, the battery 22 may be configured to be charged by power supplied via the electronic device 21.

As shown in FIG. 2, the power receiving device 23 is provided at the bottom of the cart 2. The power receiving device 23 is disposed, for example, below the lower frame portion 112. When stored in the cart base 3, the power receiving device 23 faces one of the multiple power transmitting devices 35 provided on the cart base 3.

As shown in Figures 3 and 5, the power receiving device 23 includes, for example, a casing 230, a power receiving coil 231, a power receiving board 232, and a magnetic body 233.

The casing 230 houses the power receiving coil 231 and the power receiving board 232 inside. The casing 230 is connected, for example, to the lower part of the lower frame portion 112. As a specific example, the casing 230 is fixed to the mounting portion 1125 of the lower frame portion 112.

The underside of the casing 230 is placed on the cart 2 in a position that is aligned with the floor surface on which the cart 2 travels. When multiple carts 2 are stacked and lined up and stored in the cart base 3, the casing 230 is shaped so that it does not overlap with the casings 230 of the power receiving devices 23 of adjacent carts 2 in the direction of travel of the carts 2. Furthermore, when multiple carts 2 are stacked and lined up and stored in the cart base 3, the casing 230 is placed in a position that does not overlap with or interfere with the power receiving devices 23 of adjacent carts 2 in the direction of travel of the carts 2.

The receiving coil 231 is disposed within the casing 230. The receiving coil 231 is, for example, a planar coil formed by winding a litz wire. Alternatively, the receiving coil 231 is, for example, a planar coil in which a coil pattern is formed on a printed circuit board. The receiving surface of the receiving coil 231 that receives power is, for example, formed in a planar shape. The receiving surface of the receiving coil 231 is disposed facing the floor surface on which the cart 2 travels.

When the power receiving device 23 faces the power transmitting device 35, the power receiving coil 231 is electromagnetically coupled to the power transmitting coil 351. The power receiving coil 231 generates an induced current due to the magnetic field output from the power transmitting coil 351 of the power transmitting device 35.

The receiving coil 231 is connected in series with a capacitor 2321 (described later) on the receiving board 232. By connecting the receiving coil 231 with the capacitor 2321, a receiving resonant circuit (resonant element) 239 is formed.

Here, the power receiving resonant circuit 239 composed of the power receiving coil 231 and capacitor 2321 functions, for example, as an AC power supply that supplies AC power to the rectifier circuit 2322 connected to the power receiving resonant circuit 239. For example, when using the magnetic field resonance method for power transmission, it is desirable to configure the resonant frequency of the power receiving resonant circuit 239 composed of the power receiving coil 231 and capacitor 2321 so that it is the same or nearly the same as the resonant frequency of the power transmitting resonant circuit 359 composed of the power transmitting coil 351 and capacitor 3521 (described below) of the power transmitting device 35. This improves the power transmission efficiency when the power receiving resonant circuit and power transmitting resonant circuit are electromagnetically coupled.

Note that when using electromagnetic induction for power transmission, the power receiving resonant circuit 239 may be configured with the power receiving coil 231 without including the capacitor 2321.

The power receiving board 232 includes a capacitor 2321, a rectifier circuit 2322, a voltage conversion circuit 2323, a switching circuit 2324, a load circuit 2325, a control circuit 2326, and a communication circuit 2327. By mounting electronic components and wiring patterns, for example, the power receiving board 232 is configured to include various processing circuits including the capacitor 2321, rectifier circuit 2322, voltage conversion circuit 2323, switching circuit 2324, load circuit 2325, control circuit 2326, and communication circuit 2327.

The capacitor 2321 is a capacitor for resonance.
The rectifier circuit 2322 rectifies the AC power supplied from the power receiving resonant circuit and converts it into DC power. The rectifier circuit 2322 includes, for example, a rectifier bridge configured with a plurality of diodes. A pair of input terminals of the rectifier bridge are connected to the power receiving resonant circuit 239. The rectifier circuit 2322 full-wave rectifies the AC power supplied from the power receiving resonant circuit 239, and outputs DC power from a pair of output terminals. The rectifier circuit 2322 supplies the DC power to the voltage conversion circuit 2323.

The voltage conversion circuit 2323 converts the DC voltage output from the rectifier circuit 2322 into the desired DC voltage. For example, two voltage conversion circuits 2323 may be provided. One voltage conversion circuit 23231 is connected to, for example, the rectifier circuit 2322 and the switching circuit 2324 (load circuit 2325). The voltage conversion circuit 23231 converts the DC power supplied from the rectifier circuit 2322 into DC power of a voltage suitable for charging, which is output to the load circuit 2325. The other voltage conversion circuit 23232 is connected to the rectifier circuit 2322 and the control circuit 2326. The other voltage conversion circuit 23232 converts the DC power supplied from the rectifier circuit 2322 into DC power suitable for the voltage required to operate the control circuit 2326.

The switching circuit 2324 switches between the connection and disconnection of the voltage conversion circuit 23231 and the load circuit 2325. The switching circuit 2324 switches between the connection and disconnection of the voltage conversion circuit 23231 and the load circuit 2325, for example, based on a signal from the control circuit 2326.

The load circuit 2325 is a load that receives DC power of the voltage generated by the voltage conversion circuit 23231. The load circuit 2325 is connected, for example, to the charging circuit 221 that charges the assembled battery 222 with power. The load circuit 2325, together with the charging circuit 221, performs, for example, a charging process that stores the DC power of the voltage generated by the voltage conversion circuit 23231 in the assembled battery 222. Note that the load circuit 2325 may not be provided in the power receiving device 23, and the charging circuit 221 of the battery 22 may perform the function of the load circuit 2325. Furthermore, if the power receiving device 23 is configured to have an output terminal that supplies power to the electronic device 21, the power receiving device 23 may not have the load circuit 2325. That is, in this embodiment, a configuration is described in which the power receiving device 23 has a load circuit 2325, but the load circuit 2325 may be provided external to the power receiving device 23, and the switching circuit 2324 of the power receiving device 23 may be connected to the external load circuit via a connector or the like.

The control circuit 2326 controls the operation of the load circuit 2325. The control circuit 2326 is a processing circuit. The control circuit 2326 includes, for example, a processor and a memory. The processor executes arithmetic processing. The processor performs various processes based on, for example, programs stored in the memory and data used in the programs. The memory stores programs, data used in the programs, and the like. The control circuit 2326 may be configured with a microcomputer and/or an oscillator circuit, etc.

The communication circuit 2327 wirelessly communicates information regarding power transmission and reception with the power transmission device 35.

The magnetic body 233 is provided, for example, on the side opposite the power receiving surface of the power receiving coil 231. The magnetic body 233 is formed in a sheet or plate shape.

As shown in Figures 1 and 2, the cart 2 is stored in a cart base 3 provided at a predetermined storage position. In Figures 1 and 2, the cart base 3 stores multiple carts 2 nested one inside the other.

The cart base 3, which serves as a storage device for storing the cart 2, includes a guide base 31 serving as a base portion, a cart gate 32, and multiple power transmission devices 35 supported by the guide base 31.

The guide base 31 comprises a plate-shaped support platform 311 that is placed in a predetermined storage position. The support platform 311 has, on its upper surface, multiple guide rails 312 that extend in one direction and multiple guide grooves 313 formed between the multiple guide rails 312. The support platform 311 also has protrusions and grooves that guide the storage positions of multiple carts 2. The guide base 31 regulates the movement of the front and rear wheels 153 using the guide rails 312 and guide grooves 313, thereby guiding the running direction of the cart 2 on the support platform 311. The guide base 31 also supports multiple power transmission devices 35 at equal intervals.

The cart gate 32 comprises a pair of poles 322 erected from both sides of the guide base 31, and side bars 323 arranged at a predetermined height on both side edges of the guide base 31 and extending in one direction.

Multiple power transmission devices 35 are provided between a pair of guide grooves 313 on the guide base 31, along which the pair of front wheels 153 of the cart 2 are guided. The multiple power transmission devices 35 are arranged side by side in the extension direction of the pair of guide grooves 313 on the guide base 31. Here, the extension direction of the guide grooves 313 is the direction in which the cart 2 travels on the guide base 31. In other words, the extension direction of the guide grooves 313 is the stacking direction of the multiple carts 2 on the guide base 31. The multiple power transmission devices 35 face the power receiving devices 23 of the multiple carts 2 stored in a stack on the cart base 3. The power transmission devices 35 transmit power contactlessly to the power receiving devices 23 of the opposing carts 2.

As shown in Figures 3 to 5, the power transmission device 35 includes, for example, a casing 350, a power transmission coil 351, a power transmission board 352, a fan 353, an AC adapter 354, and a magnetic body 355.

The casing 350 is formed, for example, in the shape of a rectangular box. The casing 350 houses a power transmission coil 351, a power transmission board 352, and a fan 353 inside. The casing 350 faces the power receiving device 23 of the cart 2 housed in the cart base 3, with a predetermined gap between them. The gap between the casing 350 and the casing 230 of the power receiving device 23 is several millimeters, and specifically, 1 to 10 mm.

The casing 350 has, for example, a rectangular bottom wall 3501, a rectangular top wall 3502 facing the bottom wall 3501, and four side walls 3503 connecting the bottom wall 3501 and the top wall 3502.

For example, a power transmission board 352 is disposed on the bottom wall 3501. For example, a power transmission coil 351 is fixed to the top wall 3502. When the power transmission device 35 is mounted on the cart base 3, the top surface of the top wall 3502 extends, for example, along the direction of travel of the cart 2. For example, the top surface of the top wall 3502 extends horizontally. A plurality of exhaust ports 3505 are formed in the top wall 3502.

The exhaust port 3505 is, for example, composed of one or more openings formed in the upper wall 3502. The exhaust port 3505 is formed in various shapes, such as a circle, a rectangle, or an arc. The multiple exhaust ports 3505 face multiple gaps 3512 formed in the winding 3511 (described below) and multiple magnetic holes 3551 formed in the magnetic body 355 (described below). The multiple exhaust ports 3505 are formed in positions and shapes that allow air discharged from the multiple exhaust ports 3505 and coming into contact with the casing 230 of the power receiving device 23 facing the power transmitting device 35 to move into the area of the upper wall 3502 where the power transmitting coil 351 is located. The multiple exhaust ports 3505 are formed, for example, at symmetrical positions around the center of the power transmitting coil 351 or a predetermined position near the center. Note that the arrangement of the multiple exhaust ports 3505 is not limited to symmetrical positions.

In other words, the multiple exhaust ports 3505 can be appropriately positioned so that air exhausted from the exhaust ports 3505 is supplied to a position on the upper surface of the upper wall 3502 that faces the area where the power transmission coil 351 is provided.

At least one of the four side walls 3503 has an air intake 3507 formed in it to introduce external air into the casing 350.

A predetermined gap is formed between the bottom wall 3501 and the top wall 3502 of such a casing 350. Here, the predetermined gap between the bottom wall 3501 and the top wall 3502 refers to the distance between the opposing bottom wall 3501 and top wall 3502 that allows air to flow from the intake port 3507 formed in the side wall 3503 to the exhaust port 3505. As a specific example, the bottom wall 3501 and the top wall 3502 are separated by a width that forms a gap that allows air to flow between the power transmission board 352 arranged on the bottom wall 3501 and the power transmission coil 351 arranged on the top wall 3502. For example, the width of the gap between the power transmission board 352 arranged on the bottom wall 3501 and the power transmission coil 351 arranged on the top wall 3502 is several centimeters, and as a specific example, is 1 cm to 10 cm.

The power transmission coil 351 is, for example, a planar coil including a winding 3511. The power transmission coil 351 is formed, for example, by winding a litz wire. The power transmission coil 351 has, for example, a planar power transmission surface for transmitting power. For example, the winding 3511 is fixed to a magnetic body 355. The power transmission coil 351 is formed by winding the winding 3511 multiple times around a planar frame with an opening in the center. For example, the power transmission coil 351 can be formed in various shapes, such as a square with two intersecting sides of approximately the same length, a rectangular shape such as a rectangle that is long in one direction, a circle, or an ellipse.

The power transmission surface of the power transmission coil 351 is arranged along the floor surface on which the cart 2 travels. The power transmission surface of the power transmission coil 351 is also housed in the cart base 3 and is aligned with the power receiving surface of the power receiving coil 231 provided on the opposing cart 2. Each power transmission coil 351 of the multiple power transmission devices 35 is provided in a position facing the power receiving coil 231 of each power receiving device 23 of the multiple carts 2 housed in the cart base 3.

As a specific example, in the power transmission coil 351, for example, of the winding 3511 wound multiple times, multiple gaps 3512 are formed between adjacent windings in the plane direction of the power transmission surface. The gaps 3512 are formed in two or more locations in the winding direction of the winding 3511. Note that while the examples in Figures 6 to 9 show examples in which gaps 3512 are formed in two locations in the winding direction of the winding 3511, gaps 3512 may be formed in three locations, or may be formed in four or more locations.

The multiple gaps 3512 are formed outside the central region of the power transmission coil 351, which is surrounded by the innermost portion of the wound winding 3511. In other words, the gaps 3512 are formed by bending a portion of the winding 3511 that is more inward than the outermost winding 35111, among the adjacent windings 3511 wound multiple times. The bent shape of the winding 3511 may be a curve with a predetermined radius of curvature, or may be a polygonal shape such as a V-shape or a rectangle formed by combining straight lines at a predetermined angle.

For example, an example of a method for manufacturing a winding 3511 in which a gap 3512 is formed by bending a portion of the winding 3511 may involve manufacturing the winding 3511 so that a portion of the winding is bent, or manufacturing an unbent winding and then bending a portion of the winding. Alternatively, another example of a method for manufacturing a winding 3511 in which a gap 3512 is formed by bending a portion of the winding 3511 may involve separately constructing an outer winding with no bend and an inner winding with a portion of a bend, and then connecting the outer winding and inner winding.

Alternatively, the multiple gaps 3512 are formed by separating a winding 3511 that is more inward than the outermost winding 35111 from the adjacent winding 3511 on the outside by a gap equal to or greater than the gap 3512 toward the center of the power transmission coil 351. Note that the spacing between adjacent windings 3511 that form a gap 3512 is wider than the spacing between adjacent windings 3511 that do not form a gap 3512.

As a specific example, the power transmission coil 351 has multiple windings 3511, and multiple gaps 3512 are formed between the outer winding 35113, which includes the outermost winding 35111, and the inner winding 35114, which includes the innermost winding 35112.

The gap 3512 may also be formed by bending and separating a portion of the adjacent winding 3511 that is wound multiple times and is located inside the outermost winding 35111.

Here, an example of the outer winding 35113 and inner winding 35114 of the winding 3511, which is wound three times, will be described. In this case, the outer winding 35113 is the outermost winding 35111, or the outermost winding 35111 and the winding 3511 adjacent to this outermost winding 35111. Furthermore, the inner winding 35114 is the innermost winding 35112 and the winding 3511 adjacent to this innermost winding 35112, or the innermost winding 35112.

An example of the outer winding 35113 and inner winding 35114 of the winding 3511, which is wound four times, will now be described. In this case, the outer winding 35113 is either the outermost winding 35111 alone, or the first two or three outermost windings 3511 including the outermost winding 35111. The inner winding 35114 is either the innermost winding 3511 including the innermost winding 35112 and the first two or three innermost windings 3511, or the innermost winding 35112 alone.

An example of the outer winding 35113 and inner winding 35114 of the winding 3511 having five turns will now be described. In this case, the outer winding 35113 is either the outermost winding 35111 only, or the winding 3511 from the outside, including the outermost winding 35111, up to the second, third, or fourth turn. The inner winding 35114 is either the innermost winding 3511 from the inside, including the innermost winding 35112, up to the fourth, third, or fourth turn, or the innermost winding 35112 only.

For example, Figure 6 shows an example of a power transmission coil 351 of the first embodiment in which the inner winding 35114 is bent toward the center of the winding 3511 of the power transmission coil 351, thereby forming two gaps 3512. The power transmission coil 351 of the first embodiment is an example of a winding 3511 formed with five turns in the shape of a rectangular frame that is long in one direction, and the winding 3511 from the innermost turn 35112 to the third turn on the long side is called the inner winding 35114. In the power transmission coil 351 of the first embodiment, the inner winding 35114 is bent, thereby forming two gaps 3512 between the outer winding 35113 and the inner winding 35114.

For example, Figure 9 shows an example of a power transmission coil 351 of the second embodiment, in which the inner winding 35114 is separated from the outer winding 35113 at a predetermined distance toward the center of the power transmission coil 351, thereby forming two gaps 3512. The power transmission coil 351 of the second embodiment is, for example, an example of a winding 3511 formed with four turns in the shape of a rectangular frame that is long in one direction, and the winding 3511 from the innermost turn 35112 on the short side to the second turn is called the inner winding 35114. In the power transmission coil 351 of the second embodiment, the inner winding 35114 is separated from the outer winding 35113 by a predetermined distance, thereby forming two gaps 3512 between the outer winding 35113 and the inner winding 35114.

The power transmission coil 351 is arranged on the upper wall 3502 so that the center of the power transmission coil 351 is at the center of the upper wall 3502 of the casing 350 or near the center of the upper wall 3502. The multiple gaps 3512 in the power transmission coil 351 face each of the multiple exhaust ports 3505 formed in the upper wall 3502.

When the power receiving device 23 and the power transmitting device 35 face each other, the power transmitting coil 351 is electromagnetically coupled to the power receiving coil 231.

The power transmission coil 351 is connected in series with a capacitor 3521 (described later) on the power transmission board 352. By connecting the power transmission coil 351 to the capacitor 3521, a power transmission resonant circuit (resonant element) 359 is formed.

Here, it is desirable that the resonant frequency of the power transmission resonant circuit 359, which is composed of the power transmission coil 351 and capacitor 3521, be configured to be the same as or nearly the same as the oscillation frequency of the oscillation circuit of the control circuit 3528. Note that when using an electromagnetic induction method for power transmission, the power transmission resonant circuit 359 may be configured only with the power transmission coil 351, without including the capacitor 3521.

The power transmission board 352 includes a capacitor 3521, a power transmission circuit 3522, a voltage conversion circuit 3523, a switching circuit 3524, a current sensor 3526, a current detection circuit 3527, a control circuit 3528, and a communication circuit 3529. By mounting electronic components and wiring patterns, for example, the power transmission board 352 configures various processing circuits including the capacitor 3521, power transmission circuit 3522, voltage conversion circuit 3523, switching circuit 3524, current sensor 3526, current detection circuit 3527, control circuit 3528, and communication circuit 3529.

Capacitor 3521, together with the transmitting coil 351, forms a resonant circuit.

The power transmission circuit 3522 generates transmission power and supplies the generated transmission power to the power transmission coil 351. For example, under the control of the control circuit 3528, the power transmission circuit 3522 generates AC power as transmission power by switching DC power supplied via an AC adapter 354 or the like. The power transmission coil 351 outputs power that can be received by the power receiving device 23 according to the transmission power supplied from the power transmission circuit 3522. The power transmission circuit 3522 generates AC power at a frequency that is the same as or approximately the same as the resonant frequency of the power transmission resonant circuit 359. The power transmission circuit 3522 has a switching element such as an FET. The power transmission circuit 3522 is switched on and off by the output of an oscillator circuit in the control circuit 3528. The power output from the power transmission circuit 3522 is transmitted to the power receiving device 23 using electromagnetic coupling, such as electromagnetic induction or magnetic field resonance, between the power transmission coil 351 and the power receiving coil 231.

The voltage conversion circuit 3523 converts the voltage of a DC power supply supplied, for example, via an AC adapter 354 connected to a commercial power source, into the desired DC voltage. As a specific example, the voltage conversion circuit 3523 generates power for operating the control circuit 3528 and supplies it to the control circuit 3528.

The switching circuit 3524 switches the connection and disconnection of the AC adapter 354 and the power transmission circuit 3522. The switching circuit 3524 switches the state of power supply from the power transmitting device to the power receiving device by connecting or disconnecting the AC adapter 354 and the power transmission circuit 3522 based on a control signal from the control circuit 3528. For example, the switching circuit 3524 supplies to the power transmitting circuit 3522 either DC power of a voltage supplied from an external DC power source or DC power of a voltage obtained by lowering the DC power supplied from the external DC power source by the voltage conversion circuit 3523. The switching circuit 3524 switches the DC power supplied to the power transmitting circuit 3522 based on the control of the control circuit 3528.

Current sensor 3526 detects the DC current input to power transmission circuit 3522. Current sensor 3526 is a small resistor connected between switching circuit 3524 and power transmission circuit 3522. Current sensor 3526 generates a potential (current detection signal) corresponding to the current transmitted from switching circuit 3524 to power transmission circuit 3522.

The current detection circuit 3527 amplifies the small signal detected by the current sensor 3526 and outputs it to the control circuit 3528.

The control circuit 3528 controls the operation of the power transmission circuit 3522. The control circuit 3528 is a processing circuit. The control circuit 3528 includes, for example, a processor and memory. The processor executes arithmetic processing. The processor performs various processes based on, for example, programs stored in the memory and data used in the programs. The memory stores programs, data used in the programs, and the like. The control circuit 3528 may be configured with a microcomputer and/or an oscillator circuit, etc.

For example, the control circuit 3528 controls the frequency of the AC power output from the power transmission circuit 3522 and controls the on/off operation of the power transmission circuit 3522. For example, the control circuit 3528 controls the switching circuit 3524 to switch between a state in which the power transmission coil 351 generates a magnetic field (power transmission state) and a state in which the power transmission coil 351 does not generate a magnetic field (standby state). The control circuit 3528 may also control the power transmission coil 351 to intermittently generate a magnetic field and change the timing of power transmission.

When a power receiving device 23 faces the power transmitting device 35, the control circuit 3528 first performs authentication processing to confirm whether the power receiving device 23 is a legitimate power receiving device 23. After authentication is established, the control circuit 3528 transmits power from the power transmitting device 35 to the power receiving device 23 and begins charging operations.

Furthermore, for example, the memory of the control circuit 3528 stores, as a threshold value, the current value that flows when a metallic foreign object 99 of a predetermined size made of a metallic material is present between the transmitting coil 351 and the receiving coil 231.

Note that here, the metallic foreign object 99 refers to an object that is at least partially or entirely made of a metallic material. The metallic foreign object 99 is located between the power receiving device 23 and the power transmitting device 35, on the power transmitting coil 351, and generates heat when the power transmitting coil 351 transmits power. Examples of metallic foreign object 99 include coins, metal pieces, pieces of paper or resin films covered with metal films or metal foils such as aluminum, clips, hairpins, and various other items.

Furthermore, a metal foreign object 99 large enough to pass a current value stored as a threshold is, for example, a metal foreign object 99 whose maximum dimension is greater than 3 cm.

The control circuit 3528 then compares the current value detected by the current sensor 3526 and the current detection circuit 3527 with the threshold value. If the current value detected by the current sensor 3526 and the current detection circuit 3527 differs from the normal current value, such as if it exceeds the threshold value, the control circuit 3528 controls the switching circuit 3524 to put the power transmission coil 351 into a standby state in which it does not generate a magnetic field.

The control circuit 3528 also controls, for example, the driving and stopping of the fan 353. As a specific example, the control circuit 3528 drives the fan 353 when the power transmission coil 351 is in a power transmission state. The control circuit 3528 also stops the fan 353 when the power transmission coil 351 is in a standby state.

The communication circuit 3529 wirelessly communicates information regarding power transmission and reception with the communication circuit 2327 of the power receiving device 23.

Fan 353 is disposed within casing 350, draws in air through intake port 3507, and exhausts air through exhaust port 3505. Fan 353 is provided, for example, on the inner surface of side wall 3503, adjacent to intake port 3507. Fan 353 is connected, for example, to control circuit 3528, and its driving and stopping are controlled by control circuit 3528.

The AC adapter 354 is, for example, located outside the casing 350 and connected to the power transmission board 352.

The magnetic material 355 is provided, for example, on the side opposite the power transmission surface of the power transmission coil 351. The magnetic material 355 is formed in a sheet or plate shape. Note that the magnetic material 355 has a magnetic material hole 3551 that opens at a portion facing the exhaust port 3505 and the gap 3512 so that at least the gap 3512 of the power transmission coil 351 connects the exhaust port 3505 in the upper wall 3502 and the internal space of the casing 350. Alternatively, multiple magnetic materials 355 may be provided spaced apart so that they are not located at a portion facing the exhaust port 3505 and the gap 3512, and the spacing (gap) between these multiple magnetic materials 355 may be the magnetic material hole 3551. In this way, the magnetic material hole 3551 faces the exhaust port 3505 and the gap 3512, thereby connecting the internal space of the casing 350 and the exhaust port 3505 in the upper wall 3502.

In the power supply system 1 having the power transmission device 35 configured in this manner, multiple gaps 3512 are formed in the winding 3511 of the power transmission coil 351, and magnetic material holes 3551 are formed in the magnetic material 355, with openings at portions facing the multiple gaps 3512 in the power transmission coil 351. The winding 3511 and magnetic material holes 3551 are then positioned opposite the exhaust port 3505 in the top wall 3502 of the casing 350. This allows the interior of the casing 350 to be connected to the exhaust port 3505 via the gaps 3512 in the winding 3511 and the magnetic material holes 3551 in the magnetic material 355. Therefore, when the fan 353 is driven, the airflow of air blown out from the exhaust port 3505 is blocked by the casing 230 of the power receiving device 23 above the top wall 3502 and flows toward the surface of the top surface of the top wall 3502.

As a result, even if a metallic foreign object 99 made of a metallic material generates heat on the upper surface of the upper wall 3502 of the casing 350 of the power transmitting device 35, the heat is exhausted from the exhaust port 3505, and the metallic foreign object 99 is cooled by the airflow caused by the casing 230 of the power receiving device 23 to flow in the surface direction of the upper wall 3502. Even if the metallic foreign object 99 made of a metallic material generates heat, the power transmitting device 35 can prevent the temperature of the metallic foreign object 99 from rising by cooling the metallic foreign object 99. In addition, the airflow flowing in the surface direction of the upper wall 3502 can also move small or light metallic foreign objects 99.

As a result, even if a metallic foreign object 99 is present on the upper surface of the area where the horizontally extending power transmission coil 351 of the power transmission device 35 is located, the power transmission device 35 and power supply system 1 can suppress a temperature rise in the metallic foreign object 99. The power transmission device 35 and power supply system 1 prevent wireless power transmission while the metallic foreign object 99 remains at a temperature rise.

Furthermore, if the control circuit 3528 detects a metal foreign object 99 of a predetermined size due to a change in the current flowing through the power transmission coil 351, it stops power transmission, thereby suppressing heat generation by the metal foreign object 99. Furthermore, when the power transmission coil 351 is in a power transmission state, the control circuit 3528 drives the fan 353, thereby generating airflow on the upper surface of the power transmission device 35 only when there is a risk that the power transmission coil 351 will cause the metal foreign object 99 to heat up. Therefore, the power transmission device 35 can reduce power consumption and suppress noise generated by driving the fan 353.

The power transmission device 35 and power supply system 1 of the above-described embodiment can suppress heat generation from the metal foreign object 99.

Note that the embodiment is not limited to the above example. In the above example, the power transmission coil 351 has a winding 3511 in which multiple gaps 3512 are formed, and the winding 3511 is provided on the magnetic body 355. However, the present invention is not limited to this. For example, the winding 3511 may be a coil pattern formed on a printed circuit board. When using such a winding 3511, multiple gaps 3512 may be formed in the coil pattern (winding 3511) of the printed circuit board, and openings may be formed in the areas where the gaps 3512 are formed on the printed circuit board, facing the magnetic body holes 3551 in the magnetic body 355.

In addition, in the above example, the cart base 3 is described as having a configuration with multiple guide grooves 313 that guide the movement of the wheels 153 of the cart 2, but this is not limited to this. The cart base 3 may be configured to guide the cart 2 so that the power receiving coil 231 of the power receiving device 23 mounted on the cart 2 is in a predetermined storage position facing the power transmitting coil 351 of the power transmitting device 35. For example, the cart base 3 may not be configured so that each guide groove 313 guides the movement of all the wheels 153 of the cart 2, but rather so that some of the guide grooves 313 guide the movement of the wheels 153 on one side.

In the above example, the power receiving device 23 of the power supply system 1 that supplies power contactlessly has been described as a shopping cart as the cart 2. However, the cart 2 equipped with the power receiving device 23 is not limited to shopping carts, and may be, for example, a picking cart used in warehouses. Furthermore, the application of the power supply system 1 is not limited to carts 2, but can also be used to supply power contactlessly to various other terminals. Furthermore, for example, the shape and specific configuration of the cart 2 and cart base 3 are not limited to those of the above embodiment.

At least one of the embodiments of the power transmission device and power supply system described above can suppress heat generation from metallic foreign objects that are at least partially made of a metallic material.

While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in a variety of other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their variations are within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

1...power supply system, 2...cart, 3...cart base, 11...frame, 12...basket section, 15...caster, 21...electronic device, 22...battery, 23...power receiving device, 31...guide base, 32...cart gate, 35...power transmitting device, 99...metal foreign object, 111...vertical frame section, 112...lower frame section, 113...horizontal frame section, 114...handle section, 115...mounting frame, 121...opening/closing panel, 151...front wheel caster, 152...rear wheel caster, 153...wheel, 154...bracket section, 211...tablet terminal, 212...product reader, 221...charging circuit, 222...battery pack, 223...battery box, 230...casing, 231...receiving coil, 232...receiving board, 233...magnetic material, 239...receiving resonance circuit, 311...support base, 312...guide rail, 313...guide groove, 322...pole, 323...side bar, 350...casing, 351...transmitting coil, 352...transmitting board, 353...fan, 354...AC adapter, 355...magnetic material, 359...transmitting resonance circuit , 1111...main frame, 1112...subframe, 1113...subframe, 1121...main frame, 1123...support frame, 1124...front connecting portion, 1125...mounting portion, 1131...link frame, 1132...link frame, 1133...link frame, 2321...capacitor, 2322...rectifier circuit, 2323...voltage conversion circuit, 2324...switching circuit, 2325...load circuit, 2326...control circuit, 2327...communication circuit, 3501...bottom wall, 3502...upper wall , 3503...side wall, 3505...exhaust port, 3507...intake port, 3511...winding, 3512...gap, 3521...capacitor, 3522...power transmission circuit, 3523...voltage conversion circuit, 3524...switching circuit, 3526...current sensor, 3527...current detection circuit, 3528...control circuit, 3529...communication circuit, 3551...magnetic hole, 23231...voltage conversion circuit, 23232...voltage conversion circuit, 35111...outermost winding, 35112...innermost winding, 35113...outer winding, 35114...inner winding.

Claims (5)

a power transmission coil having a gap formed between adjacent windings;
a casing having an upper wall on which the power transmitting coil is provided facing a power receiving device, and an exhaust port formed in the upper wall facing the gap of the power transmitting coil;
a fan provided within the casing;
A power transmission device comprising: The power transmission device of claim 1, further comprising a magnetic body provided on the power transmission coil, the magnetic body having openings at portions facing the gap and the exhaust port. The power transmission device described in claim 1 or claim 2, wherein the gap is formed by bending a portion of the adjacent winding that is more inward than the outermost winding. The power transmission device described in any one of claims 1 to 3, wherein the gap is formed by separating a winding that is inside the outermost winding from the adjacent winding on the outside. a power transmission device according to any one of claims 1 to 4, the power transmission device being arranged in a cart base that accommodates a plurality of carts along a traveling direction of the carts;
a power receiving device provided at a bottom of the cart and configured to transmit and receive power to and from the power transmitting device;
A power supply system comprising: