JP2015132534A - Current detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current detection device that heightens noise immunity, and that makes high accuracy detection possible.SOLUTION: A current detection device 1 comprises: a bus bar 11 having a structure in which a pair of long belt-like flat plates 11a facing each other are coupled together; a magnetic detection element 14, mounted on a circuit board 15, for detecting a current flowing in the bus bar 11; a housing 12 integrally formed while the tips of the pair of flat plates 11a of the bus bar 11 are exposed, and having an inner space 12d for accommodating and holding the circuit board 15 and the magnetic detection element 14 between the pair of flat plates 11a and an opening 12e opened in the inner space 12d; and a magnetic shield member 13 secured to the housing 12.

Description

  The present invention relates to a current detection device, and more particularly to a current detection device that detects a current flowing in a bus bar.

  2. Description of the Related Art A current detection device that detects an energization current of a bus bar by measuring a magnetic flux generated by a current flowing through the bus bar is often used. As a conventional example of this type of current detection device, for example, a current detection device that detects the intensity of a magnetic field generated by a current flowing in a bus bar has been proposed (see, for example, Patent Document 1).

  The conventional current detection device described in Patent Document 1 includes a core having a gap portion on one side of a substantially square shape. A bus bar is inserted through the hollow portion of the core, and a magnetic detection element mounted on the circuit board is arranged in the gap portion of the core, thereby detecting a change in magnetic flux generated in the core as a current. Is configured.

JP 2002-243768 A

  In the conventional current detection device described in Patent Document 1, when the current flowing through the bus bar changes transiently, when the magnetic flux density of the magnetic field generated by the transiently changed current is linked to the substrate of the magnetoelectric conversion element, Electromagnetic induction noise is likely to occur. Due to the electromagnetic induction noise, there is a problem that the transient characteristics of the output of the magnetoelectric conversion element deteriorate.

  Accordingly, it is an object of the present invention to provide a current detection device that improves noise resistance and enables highly accurate detection.

[1] The present invention relates to a bus bar having a structure in which a pair of opposing long strip-like flat plate portions are connected, a magnetic detection element that is mounted on a substrate and detects a current flowing through the bus bar, and the pair of bus bars. A housing that is integrally formed with the front end portion of the flat plate portion exposed, and has an internal space between the pair of flat plate portions for accommodating and supporting the substrate and the magnetic detection element, and an opening that opens to the internal space, and the housing And a magnetic shield member fixed to the current detecting device.

[2] The opening is formed on one side surface in the bus bar width direction of the housing according to [1].

[3] The board according to [1] or [2] is mounted with a connector housing that accommodates a connector terminal that is electrically connected to an external device, and the connection port of the connector housing is connected to the external space from the housing. It is characterized by being exposed to.

[4] A resin molding part for integrating the housing and the substrate is embedded in the internal space according to any one of [1] to [3].

[5] The magnetic shield member according to any one of the above [1] to [4] has a structure in which a pair of opposed long belt-like flat plate portions are connected to each other. A recessed portion that is depressed with a required step is formed on the wall surface and the lower wall surface, and the recessed portion is formed with either a convex portion or a concave portion that snap-fit joins the flat plate portion of the magnetic shield member. It is characterized by.

  According to the present invention, it is possible to effectively obtain a current detection device that has a simple configuration but has improved noise resistance and enables highly accurate detection.

It is a disassembled perspective view which shows roughly an example of the electric current detection apparatus which concerns on 1st Embodiment suitable for this invention. It is a principal part cross-sectional enlarged view of the II-II arrow of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1 for explaining the positional relationship between the bus bar and the magnetic detection element of the current detection device according to the first embodiment. It is a figure for demonstrating the magnetic field which generate | occur | produces from the bus-bar of the electric current detection apparatus which concerns on 1st Embodiment. It is a perspective view (a)-(d) for explaining an example of the manufacturing method of the current detection device concerning a 1st embodiment. It is a disassembled perspective view which shows roughly an example of the electric current detection apparatus which concerns on 2nd Embodiment. It is a disassembled perspective view which shows roughly an example of the electric current detection apparatus which concerns on a modification.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

[First Embodiment]
(Configuration of current detection device)
In FIG. 1, reference numeral 1 indicating the whole exemplifies a typical current detection device according to the first embodiment. The current detection device 1 is used to detect the magnitude of a current flowing through a drive motor of a hybrid vehicle or an electric vehicle and an external device such as a battery. Since motors for hybrid vehicles and electric vehicles are driven by three-phase AC current, three bus bars for three-phase AC power are used for electrical connection with external devices. Correspondingly, a current sensor is provided.

  As shown in FIGS. 1 and 2, the current detection device 1 includes a current detection bus bar 11 that is a conductor through which a current flows, and a magnetic detection element 14 that magnetically detects the current flowing through the bus bar 11. It is provided and used as a coreless type current sensor having no magnetic core.

  The bus bar 11 is made of a metal material such as copper or a copper alloy. One magnetic detection element 14 is not particularly limited, and is composed of a Hall IC in which an amplifier or the like is packaged as an integrated circuit. As the magnetic detection element 14, for example, a GMR element, an MR element, a Hall element, or the like can be used.

  As shown in FIGS. 1 and 2, the bus bar 11 has a pair of flat plate portions 11a and 11a having long strips facing each other, and a connecting portion 11b connecting one end portion in the length direction of the flat plate portion 11a. Thus, the sandwich structure has a vertical cross-sectional shape formed in a U-shape. Flat plate-like connecting portions 11c and 11c are formed at the tip ends of the pair of flat plate portions 11a, which are on the same plane as the flat plate portion 11a and extend in opposite directions. A circular connection hole 11d is formed through the connection portion 11c.

  As shown in FIGS. 1 and 2, the housing 12 is integrally formed on the flat plate portion 11a and the connecting portion 11b of the bus bar 11 by an insert molding method with the connecting portion 11c of the bus bar 11 protruding from the resin base material. Has been. As the resin material of the housing 12, a material excellent in insulation and moisture resistance is preferable. For example, polyphenylene sulfide (PPS) resin or the like is used.

  As shown in FIGS. 1 and 2, the housing 12 has a box structure having an upper wall surface 12a, a lower wall surface 12b, and three side wall surfaces 12c, ..., 12c that connect the upper wall surface 12a and the lower wall surface 12b. It is said that. An opening 12 e that opens into the internal space 12 d of the housing 12 is formed on one side surface of the housing 12 in the bus bar width direction. By forming the opening 12e on one side surface of the housing 12 in the bus bar width direction, an external space is secured so that the insertion of the assembly parts such as the magnetic detection element 14 into the internal space 12d of the housing 12 is not hindered. Has been.

  As shown in FIG. 1 and FIG. 2, a recessed portion 12 f that is depressed with a required step is formed on the upper wall surface 12 a and the lower wall surface 12 b of the housing 12 and the side wall surface 12 c on the connecting portion 11 b side of the bus bar 11. ing. A magnetic shield member 13 for preventing interference between magnetic fields formed by the adjacent bus bars 11 is fitted into the recessed portion 12f. The magnetic shield member 13 has a pair of flat plate portions 13a and 13a disposed to face each other via a connecting portion 13b, and has a U-shaped longitudinal cross-sectional shape.

  As shown in FIGS. 1 and 2, a circular locking hole 13 c is formed through the flat plate portion 13 a of the magnetic shield member 13. This locking hole 13c is snap-fit engaged with a cylindrical locking projection 12g formed to protrude from the upper wall surface 12a and the lower wall surface 12b of the housing 12. If the snap-fit engagement structure has a concavo-convex structure to be concavo-convexly coupled, for example, a locking projection is formed on the flat plate portion 13a of the magnetic shield member 13, and the engagement is formed on the upper wall surface 12a and the lower wall surface 12b of the housing 12. Of course, the structure which forms a stop hole may be sufficient.

  The magnetic shield member 13 is made of a resin material having bending elasticity or a nonmagnetic metal material. For example, PC (polycarbonate) or PET (polyethylene terephthalate) is used as the resin material. As the nonmagnetic metal material, for example, copper or aluminum is used. By configuring the housing 12 using the magnetic shield member 13, the influence of the external magnetic field generated from the other adjacent bus bar 11 is eliminated without weakening the magnetic field passing through the magnetic detection element 14, so that the output can be reduced. Increase the measurement range.

  On the other hand, the magnetic detection element 14 is mounted on the substrate 15 as shown in FIGS. 1 and 2. The substrate 15 is provided with a connector housing 16 having connection terminals (not shown) that are electrically connected to a processing circuit for processing the output from the magnetic detection element 14. The connector housing 16 is electrically connected to an external device such as a control unit (not shown).

  The board 15 on which the connector housing 16 and the like are mounted is supported by a pair of guide grooves 12h and 12h formed in the internal space 12d of the housing 12, as shown in FIGS. Are embedded in the resin molding portion 17 with the connection port exposed to the external space. The housing 12 and the substrate 15 are integrated by the resin molding portion 17. The internal space 12d of the housing 12 has a shielding effect and is hardly affected by external noise. As the resin material of the resin molded portion 17, a resin material having good compatibility with the housing 12 is preferable.

(Operation of current detection device)
As shown in FIGS. 3 and 4, the substrate 15 is arranged in parallel to the direction of the magnetic field generated between the pair of flat plate portions 11 a of the bus bar 11. On the other hand, the magnetic sensing element 14 is preferably arranged in parallel between the pair of flat plate portions 11a of the bus bar 11 and on the center line C between the pair of flat plate portions 11a. is there.

In each of the pair of flat plate portions 11a of the bus bar 11, a current A flows in the opposite direction as shown in FIG. Magnetic fluxes B ₁ and B _{2 that} are approximately proportional to the magnitude of the current A are generated around the bus bar 11. Magnetic fluxes B ₁ and B ₂ generated by the current A flowing through the bus bar 11 pass through the magnetic sensing surface of the magnetic detection element 14 in parallel.

When a current A in the opposite direction flows through the pair of flat plate portions 11a of the bus bar 11, the magnetic flux linked to the substrate 15 generated in the Z direction of the bus bar 11 is canceled out. Magnetic fluxes B ₁ and B ₂ generated in the X and Y directions are amplified between the pair of flat plate portions 11 a of the bus bar 11. The magnetic fluxes B ₁ and B ₂ are detected by the magnetic detection element 14, and an electric signal corresponding to the magnetic flux obtained by adding the magnetic fluxes B ₁ and B ₂ is output to an external device such as a control unit.

(Method for manufacturing current detection device)
The current detection device 1 configured as described above is effectively manufactured by the following manufacturing method. In manufacturing the current detection device 1, first, as shown in FIGS. 5A and 5C, the magnetic shield member 13 and the substrate 15 on which the magnetic detection element 14 and the connector housing 16 are mounted are manufactured. Keep it. Meanwhile, a conductive metal plate is punched and bent to prepare a bus bar 11 having a required shape.

  Next, as shown in FIG. 5B, the bus bar 11 is insert-molded into the housing 12 using a mold for molding the entire shape of the housing 12. An opening 12e communicating with an internal space 12d formed on one side surface of the housing 12 in the bus bar width direction is formed. As a result, the magnetic detection element 14 and the connector housing 16 are prevented from interfering with the bus bar 11 when the board 15 is assembled, and the efficiency of the work of housing and fixing the board 15 in the internal space 12d of the housing 12 is improved. .

  Next, as shown in FIG. 5C and FIG. 5D, the substrate 15 prepared in advance is inserted and supported in the internal space 12d through the opening 12e of the housing 12, and the internal space 12d. The resin molding part 17 is shape | molded by sealing an inside by potting. Next, the shield member 13 prepared in advance is snap-fit coupled to the housing 12. The current detection device 1 is completed by the above process. Of course, the housing 12 and the shield member 13 can be coupled by various methods other than snap-fit.

(Effects of the first embodiment)
By adopting the current detecting device 1 configured as described above, the following effects can be obtained in addition to the above effects.

(1) With a simple configuration, dv / dt (voltage change per unit time) dv / dt noise characteristics by canceling the magnetic flux linked to the substrate 15 generated in the Z direction of the bus bar 11 as a noise generation source. Can be obtained effectively.
(2) Since the pair of flat plate portions 11a have the bus bars 11 through which the currents A flow in opposite directions, the range of the magnetic field can be limited, and the magnetic field does not interlink the substrate 15. , Noise resistance can be improved.
(3) Since the bus bar 11 has a sandwich structure, the uniformity of the magnetic field generated by the current A flowing through the bus bar 11 is increased, and the robustness against disturbances such as dv / dt noise is increased.
(4) Arranging the substrate 15 in parallel with the magnetic field generated by the current A flowing through the bus bar 11 prevents the magnetic field from interlinking the substrate 15, thereby preventing malfunction of the substrate 15.

[Second Embodiment]
Referring to FIG. 6, there is illustrated a current detection device 1 according to the second embodiment. In FIG. 6, the same member names and symbols are assigned to the substantially same members as those in the first embodiment. Therefore, the detailed description regarding these members is omitted.

  In the first embodiment, the connector housing 16 is provided on the substrate 15. In the second embodiment, the first housing is provided with the connector housing 16 on the housing 12. The form is different.

  In FIG. 6, the housing 12 is integrally formed on the flat plate portion 11 a of the bus bar 11 by an insert molding method with the bus bar 11 disposed on one side. The housing 12 is formed with an opening 12e penetrating between the pair of flat plate portions 11a of the bus bar 11 toward the connecting portion 11c in a state where the connecting portion 11c of the bus bar 11 protrudes to the outside.

  As shown in FIG. 6, a connector housing 16 that accommodates four press-fit connector terminals 18,..., 18 is integrally formed on the upper wall surface 12 a of the housing 12. The connector terminal 18 is formed with a press-fit portion 18a having a deformable slit.

  On the other hand, as shown in FIG. 6, a press-fit through hole 15 a for press-fitting and fixing the press-fit portion 18 a of the connector terminal 18 is formed in the substrate 15. The through hole 15a is electrically connected to a processing circuit (not shown) that processes the output from the magnetic detection element 14.

(Effect of the second embodiment)
The current detection device 1 according to the second embodiment configured as described above can be fixed to the substrate 15 without using solder in addition to the same effects as those of the first embodiment. In addition, the connection quality of each of the plurality of connector terminals 18 can be managed individually.

[Modification]
In the current detection device 1 according to the present invention, the following modifications are possible.

  In the first embodiment, the configuration in which the opening 12e is provided on one side surface in the bus bar width direction of the housing 12 integrally formed with the bus bar 11 by the insert molding method is illustrated, but is not limited to the illustrated example. . As shown in FIG. 7, the opening 12 e of the housing 12 may have a configuration provided on one side surface of the housing 12 in the bus bar length direction. The substrate 15 on which the magnetic detection element 14 is mounted is inserted and supported in the internal space 12d of the housing 12 through the opening 12e formed between the pair of connection portions 11c of the bus bar 11.

  As is clear from the above description, typical embodiments, modifications, and illustrations according to the present invention have been illustrated. However, the above-described embodiments, modifications, and illustrations show the invention according to the claims. It is not limited. Therefore, it should be noted that not all the combinations of features described in the above-described embodiments, modifications, and illustrated examples are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 1 ... Current detection apparatus, 11 ... Bus bar, 11a, 13a ... Flat plate part, 11b, 13b ... Connection part, 11c ... Connection part, 11d ... Connection hole, 12 ... Housing, 12a ... Upper wall surface, 12b ... Lower wall surface, 12c ... Side wall surface, 12d ... internal space, 12e ... opening, 12f ... concave part, 12g ... locking protrusion, 12h ... guide groove, 13 ... magnetic shield member, 13c ... locking hole, 14 ... magnetic detection element, 15 ... substrate , 15a ... through hole, 16 ... connector housing, 17 ... resin molding part, 18 ... connector terminal, 18a ... press fit part, A ... current, B ₁ , B ₂ ... magnetic flux, C ... center line

Claims (5)

A bus bar having a structure in which a pair of opposing long strip-like flat plate portions are connected;
A magnetic detecting element mounted on a substrate and detecting a current flowing through the bus bar;
The bus bar is integrally formed with the front ends of the pair of flat plate portions exposed, and has an internal space for accommodating and supporting the substrate and the magnetic detection element between the pair of flat plate portions and an opening that opens to the internal space. A housing;
A magnetic shield member fixed to the housing;
A current detection device comprising:   The current detection device according to claim 1, wherein the opening is formed on one side surface of the housing in the bus bar width direction.   2. A connector housing for accommodating a connector terminal electrically connected to an external device is mounted on the substrate, and a connection port of the connector housing is exposed from the housing to an external space. Or the electric current detection apparatus of 2 description.   The current detection device according to claim 1, wherein a resin molding part for integrating the housing and the substrate is embedded in the internal space. The magnetic shield member has a structure in which a pair of opposed long strip-like flat plate portions are connected,
The housing is formed with a recessed portion depressed with a required step on the upper wall surface and the lower wall surface,
5. The current detection according to claim 1, wherein the concave portion is formed with either a convex portion or a concave portion that snap-fit joins the flat plate portion of the magnetic shield member. apparatus.

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