JP2012141262A - Current detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coreless type current detection device in which variation of a gap between a magnetoelectric transducer and a bus bar due to a dimensional tolerance and thermal expansion is prevented, and consequently variation of current detection sensitivity is prevented.SOLUTION: The current detection device 10 includes an electronic board 2 on which a hall element 1 is mounted, a metal spacer 5, and a current detection bus bar 6. The electronic board 2, spacer 5, and current detection bus bar 6 are connected with a connection mechanism comprising a plurality of screws 4 passing through a plurality of first through holes 21 at both sides of the hall element 1 on the electronic board 2, through holes of the tubular spacer 5, and a plurality of third through holes 62 of the current detection bus bar 6; and a plurality of screw receiving sections 63 to which the screws 4 are screwed.

Description

  The present invention relates to a current detection device that detects a current flowing through an electric wire.

  A vehicle such as a hybrid vehicle or an electric vehicle is often equipped with a current detection device that detects a current flowing through a bus bar connected to a battery. As such a current detection device, a magnetic proportional current detection device or a magnetic balance current detection device may be employed.

  As shown in Patent Document 1, a magnetic proportional type or magnetic balance type current detection device is disclosed in Patent Document 2, which is a first type including a magnetic core and a magnetoelectric conversion element (magnetic sensitive element). As described above, there is a second type including a magnetoelectric conversion element arranged with a very small gap with respect to the bus bar. The magnetoelectric conversion element is an element that detects magnetism and outputs a detection signal representing the strength of magnetism as an electric signal. As the magnetoelectric conversion element, a Hall element is usually adopted.

  The magnetic core in the first type is a generally ring-shaped magnetic body that is formed in a series of both ends that face each other via a gap portion and surround the periphery of the hollow portion. The hollow portion of the magnetic core is a space (current detection space) through which a current to be detected passes. The magnetic core plays a role of amplifying the surrounding magnetism that changes in accordance with a change in the current flowing through the hollow portion. In the first type, the magnetoelectric conversion element is disposed in the gap portion of the magnetic core.

  On the other hand, the second type of current detection device is a coreless type that includes a magnetoelectric conversion element and a support that supports the magnetoelectric conversion element in the vicinity of the bus bar, but does not include a magnetic core. Therefore, the second type current detection device is excellent in that it can be miniaturized.

  By the way, in the coreless type current detection device, since the magnetoelectric conversion element detects a minute change in magnetism in the vicinity of the current transmission path, if the position of the magnetoelectric conversion element with respect to the bus bar varies, the current detection sensitivity Vary greatly. Therefore, in the coreless type current detection device, it is important for the stabilization of the quality of the device to position the magnetoelectric conversion element with high accuracy with respect to the bus bar.

  In the current detection device disclosed in Patent Document 2, a magnetoelectric conversion element (magnetic detection element) is mounted on an electronic board, and the electronic board is attached to a resin housing. The housing is used for current detection by screws or the like. It is attached to the bus bar.

JP 2009-128116 A JP 2010-243440 A

  However, as shown in Patent Document 2, when an electronic board on which a magnetoelectric conversion element is mounted is attached to a bus bar through a resin housing larger than the electronic board, due to dimensional tolerance of the housing and thermal expansion. The gap between the magnetoelectric transducer and the bus bar is likely to vary. That is, the conventional coreless type current detection device has a problem in that variations in current detection sensitivity due to dimensional tolerance of the housing and thermal expansion are likely to occur.

  It is an object of the present invention to prevent variations in the distance between the magnetoelectric transducer and the bus bar due to dimensional tolerances and thermal expansion in a coreless type current detection device, and thus prevent variations in current detection sensitivity.

The current detection device according to the present invention includes the following components.
(1) A 1st component is a magnetoelectric conversion element which detects the magnetism which arises when an electric current flows.
(2) The second component is an electronic substrate in which the magnetoelectric conversion element is mounted on a first surface and a plurality of first through holes are formed at positions on both sides of the magnetoelectric conversion element.
(3) The third component is a plurality of cylindrical members in which a second through hole communicating with the first through hole is formed, and a first end is in contact with the first surface of the electronic substrate.
(4) The fourth component includes a plurality of third through holes that communicate with the second through holes of the plurality of cylindrical members, and terminal portions that are connected to the connection ends of the front and rear stages of the current transmission path. And a current detection bus bar comprising a conductor in contact with a second end opposite to the first end of the plurality of cylindrical members in a state where a gap is formed between the magnetoelectric transducer and the magnetoelectric conversion element. .
(5) The fifth component includes a plurality of screws that are passed through the first through hole, the second through hole, and the third through hole, and a plurality of screw receiving portions that are screwed together with the screws. It is a connection mechanism that connects the substrate, the plurality of cylindrical members, and the current detection bus bar.

  Further, it is conceivable that the current detection device according to the present invention further includes the following components. That is, the sixth component is a cover member that is connected to the electronic board by the connecting mechanism and covers a space between the electronic board and the current detection bus bar. Further, in this case, it is preferable that a conductive film electrically connected to the ground pattern of the electronic substrate is formed on the outer surface of the cover member.

  Moreover, in the current detection device according to the present invention, it is conceivable that the screw receiving portion is a burring portion of the edge portion of the third through hole in the current detection bus bar.

  Further, in the current detection device according to the present invention, each of the plurality of cylindrical members may be a metal member. In this case, it is also conceivable that each of the plurality of cylindrical members is mounted on the electronic board.

  Since the current detection device according to the present invention is a coreless type, it is suitable when the space around the bus bar is narrow. In the current detection device according to the present invention, the electronic board on which the magnetoelectric conversion element is mounted is connected to the current detection bus bar by sandwiching the cylindrical member through which the screw passes by a connection mechanism including the screw. That is, the cylindrical member is a spacer that maintains a constant gap between the magnetoelectric conversion element of the electronic substrate and the current detection bus bar. In the current detection device according to the present invention, the cylindrical member is a small member that surrounds the periphery of the screw in a narrow gap between the electronic board and the bus bar, so that there is very little dimensional tolerance and thermal expansion.

  Therefore, if the current detection device according to the present invention is employed, variations in the distance between the magnetoelectric transducer and the bus bar due to dimensional tolerance and thermal expansion hardly occur, and variations in current detection sensitivity can be prevented.

  In addition, if the cover member that covers the space between the electronic board and the current detection bus bar is connected to the electronic board by the connection mechanism, entry of foreign matter into the mounting surface of the magnetoelectric conversion element on the electronic board is prevented, Inconveniences such as short circuit are avoided.

  Further, in the current detection device according to the present invention, if the conductive film electrically connected to the ground pattern of the electronic substrate is formed on the outer surface of the cover member, the magnetic noise and the radio noise are It is blocked before reaching the conversion element. As a result, the magnetoelectric conversion element can be prevented from being affected by magnetic noise or radio wave noise, and fluctuations in current detection sensitivity.

  Further, in the current detection device according to the present invention, if the screw receiving portion is a burring portion in the current detection bus bar, the electronic board is compared with a case where an independent member such as a nut is employed as the screw receiving portion. The operation of connecting the cylindrical member and the current detection bus bar is facilitated.

  Moreover, since the metal member has a markedly smaller coefficient of linear thermal expansion than the resin member, it is preferable that the cylindrical member functioning as the spacer is a metal member. Further, when the cylindrical member is a metal member, it is easy to mount the cylindrical member on the electronic substrate by soldering. And if the cylindrical member is mounted with respect to the electronic board, the operation | work of a connection of an electronic board, a cylindrical member, and the bus bar for electric current detection will become easy rather than the case where a cylindrical member is an independent member.

1 is a perspective view of a current detection device 10 according to a first embodiment of the present invention. 1 is a plan view of a current detection device 10. FIG. 1 is a cross-sectional view of a current detection device 10. FIG. It is a perspective view of 10 A of electric current detection apparatuses which concern on 2nd Embodiment of this invention. It is a top view of 10 A of electric current detection apparatuses. It is sectional drawing of 10 A of electric current detection apparatuses.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example embodying the present invention, and is not an example of limiting the technical scope of the present invention.

  The current detection devices 10 and 10A according to the embodiments of the present invention are coreless type currents that detect current flowing in a bus bar that electrically connects devices such as a battery and a motor in a vehicle such as an electric vehicle or a hybrid vehicle. It is a detection device.

<First Embodiment>
Hereinafter, the configuration of the current detection device 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. As shown in FIGS. 1 to 3, the current detection device 10 includes a Hall element 1, an electronic board 2, a connector 3, two screws 4, two spacers 5, and a current detection bus bar 6. The two screws 4 constitute a connection mechanism that connects the electronic substrate 2, the two spacers 5, and the current detection bus bar 6. FIG. 3 is a cross-sectional view of the DD plane shown in FIG.

<Hall element (magnetoelectric conversion element)>
The Hall element 1 is an example of a magnetoelectric conversion element that is disposed in the vicinity of a bus bar through which a current flows, detects magnetism generated by the current flowing through the bus bar, and outputs a magnetic detection signal as an electric signal.

<Electronic boards and connectors>
The electronic board 2 is a printed circuit board in which the Hall element 1 is mounted on one surface and the connector 3 is mounted on the other surface. The connector 3 is a component that is electrically connected to the Hall element 1 and is connected to a mating connector provided on an unillustrated electric wire. In addition to the Hall element 1 and the connector 3, a circuit for electrically connecting the Hall element 1 and the terminal of the connector 3, amplification of the magnetic detection signal output from the Hall element 1, etc. A circuit that performs the above processing is also implemented.

  For example, on the electronic board 2, a circuit for supplying electric power input from the outside via the electric wire and the connector 3 to the hall element 1, and a detection signal of the hall element 1 are amplified, and the amplified signal is sent to the connector 3. A circuit for outputting to a terminal is provided. Thereby, the current detection device 10 can output a current detection signal to an external circuit such as an electronic control unit through the electric wire with the connector connected to the connector 3.

  Connector 3 includes a ground terminal electrically connected to the ground pattern of electronic substrate 2. The ground pattern of the electronic board 2 is electrically connected to a ground conductor such as a vehicle body via a ground terminal of the connector 3 and a ground wire connected to the ground terminal.

  Two first through holes 21 are formed at positions on both sides of the Hall element 1 in the electronic substrate 2. These first through holes 21 are holes through which the screws 4 are passed.

<Spacer>
The two spacers 5 are cylindrical members in which second through holes communicating with the first through holes 21 of the electronic substrate 2 are formed. One end of the spacer 5 is in contact with the surface of the electronic substrate 2 on which the Hall element 1 is mounted, and the other end of the spacer 5 is in contact with the surface of the current detection bus bar 6. The two spacers 5 are cylindrical members having a small linear expansion coefficient.

  For example, the spacer 5 is a metal member such as iron, aluminum, or copper. When the spacer 5 is a metal member, it is conceivable that the spacer 5 is previously mounted on the electronic substrate 2 by soldering. It is also conceivable that the spacer 5 is a cylindrical member made of a material in which glass is mixed with a resin such as polybutylene terephthalate. A resin material mixed with about 30% by weight of glass has a much smaller linear expansion coefficient than a general resin.

<Bus bar for current detection>
The current detection bus bar 6 is a plate-like conductor made of a metal such as copper, and is a part of the bus bar that electrically connects the battery and the electrical equipment. That is, a current to be detected flows through the current detection bus bar 6. The current detection bus bar 6 is a member independent of the battery-side bus bar connected in advance to the battery and the device-side bus bar connected in advance to the electrical equipment. The current detection bus bar 6 is connected to other bus bars (battery-side bus bar and device-side bus bar), both ends of which are laid in advance.

  The current detection bus bar 6 has a central portion facing the Hall element 1 mounted on the electronic substrate 2 and terminal portions 61 connected to the other bus bars of the front and rear stages laid in advance at both ends thereof. Is formed. The terminal portion 61 shown in FIGS. 1 to 3 is a portion in which a through-hole through which a bolt for connection with other bus bars in the front stage and the rear stage is passed is formed. The current detection bus bar 6 and the other bus bars at the front stage and the rear stage connected thereto form a current transmission path from the battery to the electrical equipment.

  The current detection bus bar 6 has two third through holes 62 communicating with the through holes of the two cylindrical spacers 5. The current detection bus bar 6 is in contact with the end of the two cylindrical spacers 5 opposite to the electronic substrate 2 side in a state where a gap is formed between the current detection bus bar 6 and the Hall element 1.

<Coupling mechanism>
The connection mechanism that connects the electronic substrate 2, the two spacers 5, and the current detection bus bar 6 includes two screws 4 and a screw receiving portion 63 formed on a part of the current detection bus bar 6. On the inner side of the screw receiving portion 63, a screw thread to be screwed with the screw 4 is formed. The screw receiving portion 63 is a burring portion of the edge portion of the third through hole 62 in the current detection bus bar 6.

  The two screws 4 are passed through the two first through holes 21 in the electronic substrate 2, the through holes (second through holes) of the two cylindrical spacers 5, and the third through hole 62 of the current detection bus bar 6. Furthermore, the two screw receiving portions 63 are screwed together. By tightening the screw 63 with respect to the screw receiving portion 63, the electronic substrate 2 and the spacer 5 are sandwiched between the head portion of the screw 63 and the current detection bus bar 6. As described above, the two screws 4 and the two screw receiving portions 63 connect the electronic substrate 2, the two spacers 5, and the current detection bus bar 6 with a certain gap between the Hall element 1 and the current detection bus bar 6. The connecting mechanism is configured to connect in the formed state.

<Effect>
Since the current detection device 10 is a coreless type, it is suitable when the space around the bus bar is narrow. Further, in the current detection device 10, the two spacers 5 maintain a constant gap between the Hall element 1 of the electronic substrate 2 and the current detection bus bar 6. Since the spacer 5 is a small member that surrounds the periphery of the screw 4 in a narrow gap between the electronic substrate 2 and the current detection bus bar 6, dimensional tolerance and thermal expansion hardly occur. Therefore, there is almost no variation in the distance between the Hall element 1 and the current detection bus bar 6 due to dimensional tolerance and thermal expansion, and variations in current detection sensitivity are prevented.

  In addition, since the screw receiving portion 63 is a burring portion of the current detection bus bar 6, the electronic substrate 2, the spacer 5, and the current are compared with the case where an independent member such as a nut is employed as the screw receiving portion 63. The operation of connecting the detection bus bars 6 is easy.

  Further, since the metal member has a remarkably small linear thermal expansion coefficient compared to the resin member, if the spacer 5 is a metal member, the effect of preventing variation in current detection sensitivity due to the thermal expansion of the spacer 5 is further enhanced. . Also, if the spacer 5 is mounted on the electronic board 2, the operation of connecting the electronic board 2, the spacer 5, and the current detection bus bar 6 becomes easier than when the spacer 5 is an independent member. .

Second Embodiment
Next, a current detection device 10A according to a second embodiment of the present invention will be described with reference to FIGS. This current detection device 10A has a configuration in which a cover member 7 is added to the current detection device 10 shown in FIGS. 4 to 6, the same components as those shown in FIGS. 1 to 3 are given the same reference numerals. Hereinafter, only the difference of the current detection device 10A from the current detection device 10 will be described.

  The cover member 7 provided in the current detection device 10 </ b> A is connected to the electronic substrate 2 by a connection mechanism including two screws 4 and two screw receiving portions 63, and covers the space between the electronic substrate 2 and the current detection bus bar 6. It is a member. The cover member 7 is an integrally molded member made of an insulating resin such as polyamide (PA), polypropylene (PP), or ABS resin.

  In the example shown in FIGS. 4 to 6, the cover member 7 is opposite to the mounting surface of the Hall element 1 on the electronic substrate 2 in a state where only the connection end portion of the connector 3 with the mating connector is exposed to the outside. It is formed in a box shape covering the range from the side surface to the side surface of the current detection bus bar 6 through the side surface of the electronic substrate 2.

  The cover member 7 is formed with two fourth through holes 71 communicating with the two first through holes 21 in the electronic substrate 2. The two screws 4 include two fourth through holes 71 in the cover member 7, two first through holes 21 in the electronic substrate 2, through holes (second through holes) in the two cylindrical spacers 5, and current detection. It is passed through the third through hole 62 of the bus bar 6 and further screwed into each of the two screw receiving portions 63. As described above, the two screws 4 and the two screw receiving portions 63 connect the electronic board 2, the two spacers 5, and the current detection bus bar 6, and connect the cover member 7 to the electronic board 2.

  A conductive film 8 electrically connected to the ground pattern of the electronic substrate 2 is formed on the outer surface of the cover member 7. The conductor film 8 is, for example, a metal film such as copper, a copper alloy, or aluminum.

  The conductor film 8 is formed in a non-contact state with the metal screw 4 and the current detection bus bar 6. For example, the conductor film 8 is formed by plating using a mask that hides the portion of the cover member 7 that contacts the screw 4 and the portion of the cover member 7 that contacts the current detection bus bar 6.

  It is also conceivable that the cover member 7 is a member in which the first resin member and the second resin member are synthesized by two-color molding. In this case, a 1st resin member forms the part which contacts the screw 4 in the cover member 7, and the part which contacts the bus bar 6 for electric current detection, and a 2nd resin member forms another part. The first resin member is a resin member such as polycarbonate that is not plated, and the second resin member is a resin member that is plated such as ABS. And it is also conceivable that the conductor film 8 is formed by plating the member obtained by synthesizing the first resin member and the second resin member.

  Further, as a structure for electrically connecting the conductor film 8 and the ground pattern of the electronic substrate 2, the following structure is conceivable. For example, a small through hole is provided in a portion of the cover member 7 where the conductive film 8 is formed, and the conductor filled in the through hole is in contact with the conductive film 8 and the ground pattern of the electronic substrate 2. A structure is conceivable.

<Effect>
When the current detection device 10A is employed, the same effect as when the current detection device 10 is employed is obtained. Further, when the current detection device 10A is employed, the cover member 7 prevents foreign matter from adhering to the electronic substrate 2, and inconveniences such as a short circuit are avoided.

  In the current detection device 10 </ b> A, a conductor film 8 electrically connected to the ground pattern of the electronic substrate 2 is formed on the outer surface of the cover member 7. Therefore, magnetic noise and radio wave noise are blocked before reaching the Hall element 1. As a result, it is possible to prevent the Hall element 1 from being affected by magnetic noise or radio wave noise and changing the current detection sensitivity.

<Others>
The current detection devices 10 and 10A described above each include the first through hole 21 of the electronic substrate 2, the cylindrical spacer 5, the third through hole 62 of the current detection bus bar 6, and two screws 4. However, it is also conceivable that three or more of them are provided. For example, when a plurality of Hall elements 1 are mounted side by side on the electronic board 2, the widths of the electronic board 2 and the current detection bus bar 6 are slightly widened. In such a case, three or four sets of first through holes 21, spacers 5, third through holes 62, and screws 4 are divided on both sides of the plurality of Hall elements 1 to form triangular vertices or quadrangular vertices. It is also conceivable to be provided at the position.

DESCRIPTION OF SYMBOLS 1 Hall element 2 Electronic board 3 Connector 4 Screw 5 Spacer 6 Current detection bus bar 7 Cover member 8 Conductive film 10, 10A Current detection device 21 First through hole 61 Terminal portion 62 Third through hole 63 Screw receiving portion 71 First Four through holes

Claims (6)

A current detection device including a magnetoelectric conversion element for detecting magnetism generated by current flow,
An electronic substrate on which the magnetoelectric conversion element is mounted on a first surface, and a plurality of first through holes are formed at positions on both sides of the magnetoelectric conversion element;
A plurality of cylindrical members formed with a second through hole communicating with the first through hole, a first end contacting the first surface of the electronic substrate;
A plurality of third through-holes communicating with the second through-holes of the plurality of cylindrical members, and terminal portions connected to the connection ends of the front stage and the rear stage of the current transmission path, and the magnetoelectric conversion element; A current detecting bus bar made of a conductor in contact with a second end opposite to the first end in the plurality of cylindrical members in a state where a gap is formed between them;
The first through-hole, the second through-hole, and the third through-hole, and a plurality of screws, and a plurality of screw receiving portions screwed together, the electronic substrate, the plurality of cylindrical members and the A current detection device comprising: a connection mechanism for connecting a current detection bus bar.   The current detection device according to claim 1, further comprising a cover member connected to the electronic substrate by the connection mechanism and covering a space between the electronic substrate and the current detection bus bar.   The current detection device according to claim 2, wherein a conductive film electrically connected to a ground pattern of the electronic substrate is formed on an outer surface of the cover member.   4. The current detection device according to claim 1, wherein the screw receiving portion is a burring portion of an edge portion of the third through hole in the current detection bus bar. 5.   The current detection device according to claim 1, wherein each of the plurality of cylindrical members is a metal member.   The current detection device according to claim 4, wherein each of the plurality of cylindrical members is mounted on the electronic substrate.

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