JP2019017168A - Foreign matter detection device - Google Patents

Abstract

To provide a foreign matter detection device capable of easily detecting a foreign material even when an 8-shaped loop antenna is used.SOLUTION: A foreign matter detection device comprises: a power transmission coil 11 that generates a magnetic field in a magnetic formation space R; a plurality of 8-shaped loop antennas A to H that are laid on a magnetic field detection surface S in the magnetic formation space R, and each include two loop portions a to h; and a detection unit 13 that detects the presence or absence of a foreign matter on the basis of an induction current that occurs in the loop antennas A to H. The loop portions a to h constituting the other loop antennas A to H are disposed between the two loop portions a to h constituting each of the loop antennas A to H.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a foreign object detection device.

  For example, as described in Patent Document 1, there is a foreign object detection device that detects a foreign object based on a change in magnetic flux in a magnetic field. In such a foreign matter detection apparatus, a change in magnetic flux is detected using an 8-shaped loop antenna having two loop portions.

Patent No. 6067211

  Here, for example, when a foreign object enters so as to straddle the two loop portions constituting the 8-shaped loop antenna, the change in magnetic flux detected in each of the two loop portions cancels each other. Foreign objects may not be detected with a letter-shaped loop antenna. For this reason, it is required to make it easier to detect foreign matter even when an 8-shaped loop antenna is used.

  Accordingly, an object of the present invention is to provide a foreign object detection device that can easily detect a foreign object even when an 8-shaped loop antenna is used.

  A foreign matter detection apparatus according to an aspect of the present invention includes a magnetic field generation unit that generates a magnetic field in a magnetic field formation space, a first loop antenna that is disposed in the magnetic field formation space, and two loops that are disposed in the magnetic field formation space. An 8-shaped second loop antenna having a section, and a detection section for detecting the presence or absence of foreign matter based on the induced current generated in the first loop antenna and the second loop antenna, and between the two loop sections A first loop antenna is arranged.

  In this foreign object detection device, the first loop antenna is disposed between two loop portions constituting the 8-shaped second loop antenna. That is, since the two loop portions of the second loop antenna are separated from each other, the entry of foreign matters so as to straddle the two loop portions is suppressed, and foreign matters are easily detected. In addition, since the first loop antenna is disposed between the two loop portions of the second loop antenna, the first loop antenna can detect foreign matter that has entered between the two loop portions of the second loop antenna. Can do. As described above, the foreign object detection device can easily detect the foreign object even when the 8-shaped loop antenna is used.

  A foreign matter detection apparatus according to another aspect of the present invention includes a magnetic field generation unit that generates a magnetic field in a magnetic field formation space, and a plurality of eight-shaped loops that are disposed in the magnetic field formation space and each have two loop portions. An antenna and a detection unit that detects the presence or absence of foreign matter based on an induced current generated in the loop antenna, and a loop unit that configures another loop antenna is disposed between the two loop units that configure the loop antenna. ing.

  In this foreign matter detection device, the loop portion of another loop antenna is arranged between two loop portions constituting the 8-shaped loop antenna. That is, the two loop parts are arranged apart from each other so that another loop antenna can be arranged between the two loop parts. As a result, in the loop antenna in which the two loop portions are separated from each other, the entry of the foreign matter so as to straddle the two loop portions is suppressed, and the foreign matter is easily detected. Further, another loop antenna is arranged between two loop portions arranged apart from each other. Thereby, even if it is a case where two loop parts are arrange | positioned away, the foreign material detection apparatus can detect the foreign material which entered between the loop parts arrange | positioned apart using another loop antenna. As described above, the foreign object detection device can easily detect the foreign object even when the 8-shaped loop antenna is used.

  In all the loop antennas, a loop part constituting another loop antenna may be arranged between two loop parts constituting the loop antenna. In this case, in all the eight-shaped loop antennas, the entry of foreign matters so as to straddle between the two loop portions is suppressed, and foreign matters are easily detected. Moreover, the foreign material which entered between the two loop parts arrange | positioned apart is detected by another loop antenna. In this way, the foreign object detection device can more easily detect the foreign object even when the 8-shaped loop antenna is used.

  The loop antenna is laid on the magnetic field detection surface in the magnetic field formation space, and when viewed from the direction orthogonal to the magnetic field detection surface, the two loop parts constituting the loop antenna are located on the magnetic field detection surface in all the loop antennas. You may arrange | position symmetrically centering | focusing on the reference point. In this case, in the loop antenna arranged outside the loop antenna arranged around the reference point, the two loop portions constituting the loop antenna are arranged apart from each other. In this way, in the loop antenna in which the two loop portions are arranged apart from each other, the entry of foreign matters so as to straddle the two loop portions is suppressed, and foreign matters are easily detected. Moreover, the foreign material which entered between the two loop parts arrange | positioned apart is detected by another loop antenna. As described above, foreign matters are easily detected in the loop antenna arranged outside the loop antenna arranged around the reference point. Therefore, the foreign object detection device can detect foreign objects even more easily even when an 8-shaped loop antenna is used.

  According to various aspects of the present invention, foreign matter can be easily detected even when an 8-shaped loop antenna is used.

It is a figure showing the schematic structure of the non-contact electric supply system concerning an embodiment. It is sectional drawing which shows the structure inside the non-contact electric power feeding system of FIG. It is a figure which shows schematic structure around the antenna board | substrate of the power transmission apparatus in a non-contact electric power feeding system. It is a figure which shows an 8-shaped loop antenna. It is the schematic which shows arrangement | positioning of the loop part of a loop antenna. It is the schematic which shows arrangement | positioning of the loop part of the loop antenna in a 1st modification. It is the schematic which shows arrangement | positioning of the loop part of the loop antenna in a 2nd modification.

  Hereinafter, an embodiment of a non-contact power feeding system to which a foreign object detection device according to the present invention is applied will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the non-contact power supply system 100 includes a power transmission device 1 and a power reception device 2. The power transmission device 1 is installed on a road surface W on which the vehicle V travels. The power transmission device 1 transmits power to the power reception device 2 in a contactless manner. The power receiving device 2 is mounted on a vehicle V that is an electric vehicle, for example. The power transmission device 1 supplies power to the power receiving device 2 of the vehicle V that has arrived at the power supply position, for example, using magnetic coupling between coils such as a magnetic resonance method or an electromagnetic induction method. Note that the non-contact power feeding method is not limited to the one using magnetic coupling, and may be an electric field resonance method, for example.

  As illustrated in FIG. 2, the power transmission device 1 includes a housing 10, a power transmission coil (magnetic field generation unit) 11, an antenna substrate 12, and a detection unit 13 (see FIG. 3). The power transmission coil 11, the antenna substrate 12, and the detection unit 13 are accommodated in the housing 10.

  The power transmission coil 11 generates a magnetic field by AC power supplied from a circuit (not shown) (for example, an inverter circuit). In the present embodiment, the power transmission device 1 transmits power to the power reception device 2 located above the power transmission device 1. For this reason, the power transmission coil 11 generates a magnetic field in the space above the power transmission coil 11. A space in which the power transmission coil 11 generates a magnetic field is defined as a magnetic field formation space R. In a state where the vehicle V is stopped at the power supply position, the power receiving coil 21 of the power receiving device 2 faces the upper surface of the power transmitting coil 11 of the power transmitting device 1 and is located in the magnetic field forming space R. Thereby, power is transmitted from the power transmission coil 11 to the power reception coil 21 via the magnetic field.

  The antenna substrate 12 functions as a sensor that detects foreign substances such as metal that have entered the magnetic field forming space R. Specifically, as shown in FIG. 3, the antenna substrate 12 includes eight-shaped loop antennas A to H and a substrate 12 a on which the loop antennas A to H are laid. The loop antenna A has two loop portions a. The two loop portions a are connected so that the antenna lines intersect (cross connection). That is, when a current flows from one end of the loop antenna A toward the other end, the rotation directions (flow directions) of the currents flowing through the two loop portions a are opposite. Both ends of the loop antenna A are connected to the detection unit 13.

  The loop antennas B to H have the same configuration as the loop antenna A. That is, each of the loop antennas B to H has two loop portions b to h. Both end portions of the loop antennas B to H are connected to the detection unit 13, respectively.

  The antenna substrate 12 is installed on the magnetic field detection surface S in the magnetic field formation space R. That is, the loop antennas A to H are laid on the magnetic field detection surface S. The loop antennas A to H detect a change in magnetic flux on the magnetic field detection surface S. The magnetic field detection surface S is preset in the magnetic field formation space R as a surface for detecting magnetic flux using the loop antennas A to H. For example, the magnetic field detection surface S is orthogonal to the direction in which the power transmission coil 11 and the antenna substrate 12 face each other.

  The loop antenna A is laid on the substrate 12a so that the magnetic flux generated by the power transmission coil 11 passes through the loop part a. Also, the size of the two loop portions a and the antenna are set so that the induced current generated in one loop portion a and the induced current generated in the other loop portion a cancel each other when the power transmission coil 11 generates magnetic flux. The number of turns of the wire has been adjusted. Similarly, the loop antennas B to H are laid on the substrate 12a so that the magnetic flux generated by the power transmission coil 11 passes through the loop portions b to h. Further, like the loop part a, the sizes of the loop parts b to h, the number of turns of the antenna wire, and the like are adjusted.

  When a foreign substance exists in the magnetic field formation space R between the power transmission device 1 and the power reception device 2, the density of the magnetic flux generated by the power transmission coil 11 changes. The loop antennas A to H detect changes in magnetic flux density caused by the presence of foreign matter on the magnetic field detection surface S.

  The detection unit 13 detects the presence or absence of foreign matter in the magnetic field forming space R based on the detection results of the loop antennas A to H (induced currents generated by the loop antennas A to H). The detection unit 13 is various processors (controllers) such as an MPU (Micro Processing Unit) and a CPU (Central Processing Unit). Specifically, when there is no foreign object, no induced current is generated in the loop antennas A to H due to the magnetic flux generated by the power transmission coil 11. When there is a foreign object, the distribution of the magnetic flux generated by the power transmission coil 11 changes, and an induced current is generated in one of the loop antennas A to H. The detection unit 13 detects the presence or absence of a foreign substance based on the induced current generated in any of the loop antennas A to H. When a foreign object is detected by the detection unit 13, the power transmission device 1 stops power transmission by the power transmission coil 11, for example.

  Thus, the loop antennas A to H, the power transmission coil 11, and the detection unit 13 function as a foreign object detection device 30 that detects the presence or absence of a foreign object in the magnetic field formation space R.

  In the present embodiment, as shown in FIG. 4, the loop antenna A is arranged such that the two loop portions a are separated from each other. At least one of the loop parts b to h constituting the other loop antennas B to H is arranged between the loop parts a arranged apart from each other. Moreover, the loop part a is formed in the substantially rectangular shape as FIG. 4 shows. The loop antennas B to H have the same configuration as the loop antenna A shown in FIG. Thereby, when arrange | positioning the loop parts ah on the board | substrate 12a, the clearance gap between the loop parts ah can be decreased compared with the case where the loop parts ah are circular.

  Next, the arrangement of the loop portions a to h of the loop antennas A to H provided on the substrate 12a will be described. In the present embodiment, as shown in FIG. 5, when the antenna substrate 12 is viewed from above, the loop portions a to h are arranged in a matrix of four each in the vertical direction and the horizontal direction. Further, in FIG. 5, the arrangement positions of the respective loop portions a to h when the four a loop portions a to h are arranged in the vertical direction and the horizontal direction using the symbols a to h are shown. For example, FIG. 5 shows that two loop portions a of the loop antenna A are respectively arranged at the positions of “a (A)” on the lower left and “a (A)” on the upper right.

  As shown in FIG. 5, in all the loop antennas A to H, at least one of the other loop parts a to h is provided between the two loop parts a to h constituting the loop antennas A to H. Is arranged. Specifically, for example, a loop part h and a loop part g are arranged between two loop parts a. Similarly, for example, a loop part f and a loop part h are arranged between two loop parts e. That is, the two loop portions a are not adjacent to each other. Similarly, the two loop portions b to h are not adjacent to each other.

  As described above, in the foreign object detection device 30, at least one of the loop portions b to h of the other loop antennas B to H is disposed between the two loop portions a constituting the 8-shaped loop antenna A. ing. That is, the two loop portions a are arranged apart from each other so that other loop antennas B to H can be arranged between the two loop portions a. The other loop portions b to h are also arranged apart from each other, like the loop portion a. As a result, in the loop antenna A in which the two loop portions a are arranged apart from each other, the entry of foreign matter so as to straddle the two loop portions a is suppressed, and foreign matter is easily detected. Note that the foreign matter straddling between the two loop portions a means that the foreign matter overlaps at least a part of one loop portion a and the other loop portion a when viewed from the direction perpendicular to the magnetic field detection surface S. It is that a foreign substance overlaps at least a part. As for the other loop portions b to h, similarly to the loop portion a, the entry of foreign matter so as to straddle between the two loop portions b to h is suppressed, and the foreign matter is easily detected.

  Further, as shown in FIG. 5, a loop portion h of another loop antenna H and a loop portion g of the loop antenna G are disposed between two loop portions a that are spaced apart. Similarly to the loop part a, at least one of the loop parts a to h of the other loop antennas A to H is also arranged between the two loop parts b to h arranged apart from each other. As a result, even if the two loop portions a to h are arranged apart from each other, the foreign object detection device 30 removes the foreign matter that has entered between the separated loop portions a to h from the other loop antenna. It can detect using AH. As described above, the foreign object detection device 30 can easily detect a foreign object even when the 8-shaped loop antennas A to H are used.

  Next, a first modification will be described. The first modification differs from the configuration of the above embodiment only in the arrangement of the loop portions a to h of the loop antennas A to H. Hereinafter, the arrangement of the loop portions a to h in the first modification will be described. As shown in FIG. 6, in all the loop antennas A to H, there is at least one of the other loop portions a to h between the two loop portions a to h constituting the loop antennas A to H. Is arranged.

  Specifically, for example, a loop part h and a loop part f are arranged between two loop parts a. Similarly, for example, a loop portion f is disposed between two loop portions e. The loop portions a to d are arranged apart from each other in the vertical direction in FIG. The loop parts a to d are arranged symmetrically in the vertical direction in FIG. The loop portions e to h are arranged apart from each other in the left-right direction in FIG. That is, the two loop portions a are not adjacent to each other. Similarly, the two loop portions b to h are not adjacent to each other.

  Even when the loop antennas A to H are arranged as in the first modification, the foreign object detection device 30 has the same operational effects as the embodiment.

  Next, a second modification will be described. The second modification differs from the configuration of the above-described embodiment only in the arrangement of the loop portions a to h of the loop antennas A to H. Hereinafter, the arrangement of the loop portions a to h in the second modification will be described. Here, a predetermined position of the magnetic field detection surface S when viewed from a direction orthogonal to the magnetic field detection surface S is defined as a reference point K. In this embodiment, as shown in FIG. 7, the center position when the substrate 12a is viewed from the direction orthogonal to the magnetic field detection surface S is set as a reference point K. The two loop portions a to h constituting the loop antennas A to H are arranged symmetrically with respect to the reference point K.

  Specifically, around the reference point K (position adjacent to the reference point K), two loop portions g and two loop portions h are arranged symmetrically with respect to the reference point K. Outside the loop portions g and h, the loop portions a to f are arranged symmetrically with respect to the reference point K. That is, the two loop portions a are not adjacent to each other. Similarly, the two loop portions b to f are not adjacent to each other. Between each of the two loop portions a to f, at least one of the loop antennas G and H is located.

  As described above, when the loop portions a to h are arranged point-symmetrically, the two loop portions a constituting the loop antennas A to F arranged outside the loop portions g and h arranged around the reference point. -F are arrange | positioned away. In this way, in the loop antennas A to F in which the two loop portions a to f are arranged apart from each other, the entry of foreign matters is suppressed so as to straddle the two loop portions a to f, and foreign matters are detected. It becomes easy. In addition, the foreign matter that has entered between the two loop portions a to f that are spaced apart is detected by at least one of the other loop antennas G and H. As described above, foreign matters are easily detected in the loop antennas A to F arranged outside the loop antennas G and H arranged around the reference point K. Therefore, the foreign object detection device 30 can easily detect the foreign object even when the 8-shaped loop antennas A to H are used.

  Since the two loop portions a are arranged symmetrically with respect to the reference point K, the distance from one loop portion a to the reference point K is equal to the distance from the other loop portion a to the reference point K. Become. For the other loop portions b to h, the distance from one loop portion b to h to the reference point K is the same as the distance from the other loop portion b to h to the reference point K, similarly to the loop portion a. . In general, the density distribution of the magnetic flux generated by the power transmission coil 11 is symmetric with respect to a magnetic flux reference point such as the center position of the power transmission coil 11, for example. For this reason, by matching the position of the reference point K when arranging the loop portions a to h symmetrically with the magnetic flux reference point of the density distribution of the magnetic flux generated by the power transmission coil 11, the two loop portions a It is arranged at a position where the amount of magnetic flux interlinking is substantially the same (position where the density distribution of the magnetic flux is substantially the same). That is, in order to cancel the induced current between the two loop portions a, the configuration of the two loop portions a (the opening area of the loop and the number of turns of the antenna wire) may be the same, and the design of the loop portion a Becomes easy. Similarly to the loop portion a, the design of the loop portions b to h is facilitated for the other loop portions b to h.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, although the loop antennas A to H are all in the shape of eight, any one of the loop antennas may have only one loop portion. And the loop antenna (1st loop antenna) which has only one loop part may be arrange | positioned between the two loop parts which comprise an 8-shaped loop antenna (2nd loop antenna). Specifically, for example, the loop antenna F shown in FIG. 6 has only one loop part f, and the loop part f may be arranged between the two loop parts a.

  The shape of the loop portions a to h is a rectangle, but may be a shape other than a rectangle, such as a circle, an ellipse, a triangle, and a diamond. In the above embodiment and the like, the case where eight loop antennas A to H are used has been described as an example, but the number of loop antennas is not limited to eight. Further, although the loop portions a to h are arranged in a matrix of four each in the vertical direction and the horizontal direction, the number of loop portions arranged in the vertical direction and the horizontal direction is not limited to four. Further, although the loop portions a to h are arranged in a matrix, the present invention is not limited to being arranged in a matrix.

  For example, in the embodiment and the first modification, in all the loop antennas A to H, the other loop antennas A to H are arranged between the two loop portions a to h. A to H may not be arranged in this way. In any one or more loop antennas among the plurality of loop antennas A to H included in the foreign object detection device 30, it is only necessary that another loop antenna is disposed between the two loop portions.

  In the above-described embodiments and the like, the loop antennas A to H detect a change in magnetic flux generated by the power transmission coil 11, but may detect a change in magnetic flux generated by a magnetic field generation unit other than the power transmission coil 11. For example, in the above-described embodiment and the like, the loop antennas A to H may detect a change in magnetic flux in a magnetic field generated by a magnetic field generator provided exclusively for detecting a foreign object.

  In the above embodiment, the case where the foreign object detection device 30 is applied to the power transmission device 1 of the non-contact power supply system 100 has been described as an example, but the foreign object detection device 30 is applied to devices other than the non-contact power supply system 100. Also good. For example, the foreign object detection device 30 may be applied to a metal detection device that uses a coil and a magnetic field.

11 Power transmission coil (magnetic field generator)
13 Detection unit A to H Loop antenna a to h Loop unit K Reference point R Magnetic field formation space S Magnetic field detection surface

Claims (4)

A magnetic field generator for generating a magnetic field in the magnetic field forming space;
A first loop antenna disposed in the magnetic field forming space;
An eight-shaped second loop antenna disposed in the magnetic field forming space and having two loop portions;
A detection unit for detecting the presence or absence of a foreign substance based on an induced current generated in the first loop antenna and the second loop antenna;
With
The foreign object detection device, wherein the first loop antenna is disposed between the two loop portions. A magnetic field generator for generating a magnetic field in the magnetic field forming space;
A plurality of 8-shaped loop antennas disposed in the magnetic field forming space, each having two loop portions;
A detection unit for detecting the presence or absence of foreign matter based on an induced current generated in the loop antenna;
With
The foreign object detection device, wherein the loop part constituting the other loop antenna is arranged between the two loop parts constituting the loop antenna.   The foreign object detection device according to claim 2, wherein, in all the loop antennas, the loop portions constituting the other loop antenna are arranged between the two loop portions constituting the loop antenna. The loop antenna is laid on a magnetic field detection surface in the magnetic field forming space,
When viewed from a direction orthogonal to the magnetic field detection surface, in all the loop antennas, the two loop portions constituting the loop antenna are arranged point-symmetrically around a reference point on the magnetic field detection surface. The foreign matter detection device according to claim 2.

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