JP2005308526A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive current sensor which can prevent the deformation of a magnetic gap of a core, associated with the curing of a sealing member. <P>SOLUTION: In manufacturing the current sensor 10, articles to be accommodated (a Hall device 12, the core 14, an electronic component 21, wiring members 22-24, and a regulation member 28) are installed inside an accommodation part 17; a liquid having fluidity or the gel-like sealing member 29 is then flown into or dropped into the accommodation part 17 so as to be charged; and the articles to be accommodated are sealed in the accommodation part 17 so as to be fixed in the state in which the articles to be accommodated are positioned in the accommodation part 17, by curing the sealing member 29. Because the regulation member 28 is held in-between in the magnetic gap S of the core 14 without spacing, even when the stress generated associated with the curing of the sealing member 29 is applied to the core 14, the deformation of the magnetic gap S is prevented by the regulation member 28, and the dimensional shape of the magnetic gap S is not varied from the setting value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a current sensor, and more particularly, to a current sensor including a ring-shaped core having a magnetic gap and a Hall element disposed between the magnetic gaps of the core.

  Conventionally, it has a ring-shaped core, a magnetic gap formed by cutting and opening a part of the core, and a Hall element disposed between the magnetic gaps, and the core and the Hall element are opened above the housing. A current sensor is known that is housed in a housing portion, filled with a sealing material of a synthetic resin material in the housing portion, and a core and a Hall element are sealed by curing of the sealing material (for example, , See Patent Document 1).

  The current sensor of Patent Document 1 detects a current value flowing through a conductive member inserted through a ring-shaped core by a Hall element disposed between magnetic gaps. That is, a magnetic flux is generated in the core by the current flowing through the conductive member, and the Hall element generates a voltage (Hall voltage) due to the Hall effect corresponding to the magnetic flux. The Hall voltage generated by the Hall element not only corresponds to the magnetic flux in the core, but also corresponds to the current value flowing through the conductive member that generated the magnetic flux, and can be said to be a detection signal for the current value.

Incidentally, the current sensor of Patent Document 1 is used to detect the value of a current flowing through a conductive member (bus bar) that connects an in-vehicle battery of an automobile and a vehicle electrical component, for example.
Japanese Patent Laid-Open No. 2002-296305 (Pages 4-6, FIGS. 1 and 2)

  In order to manufacture the current sensor of Patent Document 1, first, the core and the Hall element are mounted in the housing portion, and then a liquid or gel-like sealing material having fluidity is poured into the housing portion or dropped (potting). Then, the core and the Hall element are sealed and fixed in the housing part in a state where the core and the Hall element are positioned in the housing part by curing the sealing material.

Here, the magnetic gap of the core is formed by cutting and opening a part of the core. As a result, the stress generated with the hardening of the sealing material is applied to the core, the ring-shaped core is deformed and the dimensional shape of the magnetic gap changes from the set value, and the accuracy and sensitivity of current detection by the Hall element decreases. There was a problem to do.
In particular, when a sealing material having thermosetting properties is used, a large stress is generated when the sealing material is thermally cured due to the linear expansion coefficient of the sealing material, so that the core is easily deformed by the stress.

  By the way, in order to prevent the deformation of the core accompanying the curing of the sealing material, it is sufficient to use a sealing material with a small stress generated during the curing, but since such a sealing material is expensive, the manufacture of the current sensor The problem of increased costs arises.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a current sensor capable of preventing deformation of the magnetic gap of the core accompanying hardening of the sealing material at low cost.

(Claim 1)
According to the first aspect of the present invention, there is provided a ring-shaped core in which a plurality of thin-plate core pieces are laminated and integrated, a magnetic gap formed in a part of the core, and a Hall element disposed between the magnetic gaps And a current sensor comprising a housing having a housing portion for housing the core and the Hall element, and a sealing material filled in the housing portion of the housing and sealing the core and the Hall element, A technical feature is that the housing accommodating portion is provided with deformation preventing means for preventing deformation of the magnetic gap.

(Claim 2)
According to a second aspect of the present invention, in the current sensor according to the first aspect, the magnetic gap includes a cut portion of the core, and the deformation preventing means accommodates the core in the housing portion of the casing. In this case, it is a technical feature that it comprises a restricting member that is sandwiched between the magnetic gaps without any gap.

(Claim 3: Corresponds to the first embodiment or the second embodiment)
According to a third aspect of the present invention, in the current sensor according to the second aspect, the regulating member is sandwiched between at least one of the inside and the outside of the magnetic gap.

(Claim 4: corresponds to the third embodiment)
According to a fourth aspect of the present invention, in the current sensor according to the second aspect, the restriction member surrounds the periphery of the Hall element and is sandwiched between the magnetic gaps.

(Claim 1)
In order to manufacture the current sensor according to the first aspect of the invention, first, the core and the Hall element are mounted in the housing portion, and then a liquid or gel-like sealing material having fluidity is poured or dropped into the housing portion. Then, the core and the Hall element are sealed and fixed in the accommodating portion in a state where the core and the Hall element are positioned in the accommodating portion by curing the sealing material.

At this time, since the housing accommodating portion is provided with the deformation preventing means, even if the stress generated with the hardening of the sealing material is applied to the core, the deformation of the magnetic gap is suppressed by the deformation preventing means. The dimensional shape of the magnetic gap does not change from the set value.
Therefore, according to the first aspect of the present invention, the deformation prevention means is provided in the housing housing portion to prevent the magnetic gap from being deformed due to the hardening of the sealing material, and the accuracy and sensitivity of the current detection by the Hall element is reduced. Can be avoided.

As the sealing material, any material (for example, silicon, etc.) may be used as long as the workability of filling the accommodating portion is good and the core and the Hall element can be reliably sealed after curing. Various synthetic resin materials such as urethane and epoxy may be used.
In particular, when a sealing material having thermosetting properties is used, a large stress is generated when the sealing material is thermally cured due to the linear expansion coefficient of the sealing material. According to the first aspect of the invention, since the deformation of the magnetic gap can be prevented, a thermosetting sealing material can be used.
Therefore, according to the first aspect of the present invention, there is less limitation on the material used for the sealing material, and it becomes possible to use an inexpensive sealing material instead of a large stress generated at the time of curing. Cost can be reduced.

(Claim 2)
In the current sensor according to the second aspect of the present invention, since the restricting member that is sandwiched between the magnetic gaps without any gap when the core is accommodated in the housing accommodating portion is provided as the deformation preventing means, it is generated as the sealing material is cured. Even if the stress to be applied is applied to the core, the deformation of the magnetic gap is suppressed by the restricting member, and the dimensional shape of the magnetic gap does not change from the set value.

(Claim 3)
In the current sensor according to the third aspect of the invention, since the regulating member is sandwiched between at least one of the inside and the outside of the magnetic gap, the deformation of the magnetic gap can be reliably prevented.

(Claim 4)
In the current sensor according to the fourth aspect of the invention, since the restricting member surrounds the Hall element and is sandwiched between the magnetic gaps, the restricting member is sandwiched between a part of the magnetic gaps. Since the deformation of the gap can be more reliably suppressed, the operation and effect of the invention of claim 1 can be further enhanced.

(Explanation of terms)
The deformation preventing means corresponds to the regulating members 28, 42, 52.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In each embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

(First embodiment)
FIG. 1 is an exploded perspective view of a main part for explaining a schematic configuration of a current sensor 10 according to the first embodiment.
FIG. 2 is a perspective view of the current sensor 10.
FIG. 3 is a plan view of a main part of the current sensor 10.

  The current sensor 10 includes a Hall element 12, a core 14 (core fragment 15, magnetic gap S), a housing 16 (accommodating portion 17, connector mounting portion 18, circuit accommodating portion 19, core accommodating portion 20, insertion hole 25, outer peripheral wall 26. ), Electronic component 21, wiring members 22 to 24, mounting bracket 27, regulating member (stopper) 28, sealing material 29, and the like.

The core 14 is formed by laminating and integrating a plurality of thin core pieces 15. The core piece 15 is formed by shearing (pressing) an appropriate conductive magnetic material (for example, iron, an iron-based alloy, permalloy, or the like).
The core 14 (core fragment 15) has a substantially rectangular ring shape with rounded corners formed at four corners, and a part of the ring shape (a part of a substantially rectangular short side in the illustrated example) is cut and opened to form a magnetic gap S. Is formed.

A non-magnetic housing 16 made of synthetic resin is integrally formed by injection molding with a housing portion 17 opened upward and a cylindrical connector mounting portion 18 opened laterally.
The housing portion 17 is configured by connecting a substantially box-shaped circuit housing portion 19 and a core housing portion 20 having a substantially double frame shape.

Here, the circuit housing part 19 is formed in a shallower shape than the core housing part 20, the bottom surface 19 a of the circuit housing part 19 is arranged at a position higher than the bottom surface 20 a of the core housing part 20, and the housing 16 is high and low. It has a stepped structure.
And the connector mounting part 18 is connected with the side of the circuit accommodating part 19, and the housing | casing 16 has comprised the substantially L shape as a whole.

  The Hall element 12 is attached and fixed to the bottom surface 19 a of the circuit housing portion 19, and a plurality of various electronic components 21 constituting the drive control circuit of the Hall element 12 are attached and fixed. An adhesive is used for connecting and fixing the Hall element 12 and each electronic component 21.

  The Hall element 12 and each electronic component 21 are connected via a wiring material 22, and each electronic component 21 is connected via a wiring material 23. A connector terminal (not shown) provided in the connector mounting portion 18 and each electronic component 21 are connected via a wiring member 24. The wiring members 22 to 24 are connected not by soldering but by electric welding.

A rectangular insertion hole 25 for inserting a conductive member, which will be described later, is opened at the approximate center of the bottom surface 20a of the core housing portion 20. The height of the outer peripheral wall 26 of the insertion hole 25 is the same as the height of the outer peripheral wall of the housing portion 17 (the circuit housing portion 19 and the core housing portion 20).
A mounting bracket 27 is attached and fixed to the back surface side of the bottom surface 20 a of the core housing portion 20. The mounting bracket 27 is provided with a through hole, and a bolt is inserted into the through hole and screwed into a fixed object (for example, a member in an automobile engine room) to attach the current sensor 10 to the fixed object. Can be fixed.

  The core 14 is accommodated in the accommodating portion 17. That is, the core 14 is mounted on the bottom surface 20 a of the core housing part 20 so that the core 14 is fitted to the outer peripheral wall 26 of the insertion hole 25 in the core housing part 20 and the ring-shaped core 14 surrounds the insertion hole 25. Is placed.

  The short side portion of the core 14 provided with the magnetic gap S protrudes into the circuit housing portion 19, and the Hall element 12 is disposed at a substantially central position between the magnetic gaps S so as not to contact the core 14. Has been. For example, the gap of the magnetic gap S is set to 2.5 mm, the width of the Hall element 12 is set to 1.5 mm, and the gap between the Hall element 12 and the core 14 is set to 0.5 mm.

  Between the Hall element 12 and the outer peripheral wall 26 on the bottom surface 19 a of the circuit housing portion 19, a substantially rectangular regulating member 28 is erected. The restricting member 28 has an arrangement position and a dimensional shape so that when the core 14 is accommodated in the accommodating portion 17, the restricting member 28 is interposed between the magnetic gaps S of the core 14 without a gap. The regulating member 28 is made of a non-magnetic synthetic resin material, and is integrally formed with the casing 16 by injection molding.

  The accommodating portion 17 is filled with a sealing material 29 (the hatched portion shown in FIGS. 2 and 3), and the contents (the Hall element 12, the core 14, and the electronic component 21) of the accommodating portion 17 are cured by the hardening of the sealing material 29. In addition, the wiring members 22 to 24 and the regulating member 28) are sealed, and the positional relationship of the accommodated objects in the accommodating portion 17 is positioned and fixed.

  In order to use the current sensor 10 configured as described above, first, a conductive member (not shown) to be detected is inserted into the insertion hole 25, and then an external device that inputs a detection signal of the current sensor 10 is used. A connector (not shown) is inserted into the connector mounting portion 18 to connect an external device and a connector terminal (not shown) in the connector mounting portion 18.

When a current is passed through the conductive member, a magnetic flux is generated in the core 14 by the current, and the Hall element 12 disposed in the magnetic path formed in the magnetic gap S by the magnetic flux has a Hall effect corresponding to the magnetic flux. Generates a voltage (Hall voltage).
Here, the Hall voltage generated by the Hall element 12 not only corresponds to the magnetic flux in the core 14 but also corresponds to the current value flowing through the conductive member that generated the magnetic flux. I can say that. Therefore, the Hall voltage generated by the Hall element 12 is output as a detection signal to the external device.

Therefore, the current sensor 10 can detect the current value flowing through the conductive member inserted through the ring-shaped core 14 by the Hall element 12 disposed between the magnetic gaps S of the core 14.
Incidentally, the current sensor 10 is used, for example, to detect the value of a current flowing through a conductive member (bus bar) that connects an in-vehicle battery of an automobile and a vehicle electrical component.

[Operations and effects of the first embodiment]
According to the first embodiment, the following actions and effects can be obtained.

  [1-1] In order to manufacture the current sensor 10, first, an accommodation object (Hall element 12, core 14, electronic component 21, wiring members 22 to 24, regulation member 28) is attached in the accommodation portion 17, and then Then, a liquid or gel-like sealing material 29 having fluidity is poured into the accommodating portion 17 or dropped (potted) and filled, and then the sealing material 29 is cured to accommodate the accommodation. In a state where the positioning is performed in the portion 17, the storage object is sealed and fixed in the storage portion 17.

  At this time, since the regulating member 28 is sandwiched between the magnetic gaps S of the core 14 without any gaps, the magnetic gap S is applied even if a stress generated as the sealing material 29 is cured is applied to the core 14. The deformation is suppressed by the restricting member 28, and the dimensional shape of the magnetic gap S does not change from the set value.

  Therefore, according to the first embodiment, by providing the regulating member 28, the deformation of the magnetic gap S of the core 14 due to the hardening of the sealing material 29 is prevented, and the accuracy and sensitivity of current detection by the Hall element 12 are reduced. Can be avoided.

  [1-2] The sealing material 29 has good filling workability in the housing portion 17, and the contents (the hall element 12, the core 14, the electronic component 21, and the wiring materials 22 to 24) in the housing portion 17 after curing. Any material (for example, various synthetic resin materials such as silicon, urethane, and epoxy) may be used as long as it is a non-magnetic material that can reliably seal the regulating member 28).

  In particular, when the sealing material 29 having thermosetting property is used, a large stress is generated when the sealing material 29 is thermally cured due to the linear expansion coefficient of the sealing material 29, and therefore the core 14 is deformed by the stress. However, since the deformation of the magnetic gap S can be prevented according to the first embodiment, the thermosetting sealing material 29 can be used.

  Therefore, according to the first embodiment, the limitation on the material used for the sealing material 29 is reduced, and an inexpensive sealing material can be used instead of a large stress generated during curing. Manufacturing cost can be reduced.

  [1-3] The regulating member 28 is integrally formed with the housing 16 by injection molding. Therefore, according to the first embodiment, it is not necessary to add a special manufacturing process to form the regulating member 28, and the production cost of the current sensor 10 does not increase by providing the regulating member 28.

(Second Embodiment)
FIG. 4 is an exploded perspective view of a main part for explaining a schematic configuration of the current sensor 40 of the second embodiment.
FIG. 5 is a perspective view of the current sensor 40.
FIG. 6 is a main part plan view of the current sensor 40.

The second embodiment is different from the current sensor 10 of the first embodiment only in that the regulating member 28 is omitted and a regulating member 42 having the same size and shape as the regulating member 28 is provided instead. .
That is, the current sensor 40 includes the Hall element 12, the core 14 (core piece 15, magnetic gap S), the housing 16 (accommodating portion 17, connector mounting portion 18, circuit accommodating portion 19, core accommodating portion 20, insertion hole 25, outer periphery Wall 26), electronic component 21, wiring members 22 to 24, mounting bracket 27, sealing material 29, regulating member 42, and the like.

The Hall element 12 is attached and fixed between the regulating member 42 and the outer peripheral wall 26 on the bottom surface 19 a of the circuit housing portion 19. The restricting member 42 has an arrangement position and a dimensional shape so that when the core 14 is accommodated in the accommodating portion 17, the restricting member 42 is interposed between the magnetic gaps S of the core 14 without any gap. The regulating member 42 is made of a non-magnetic synthetic resin material and is integrally formed with the housing 16 by injection molding.
In other words, the restriction member 28 of the first embodiment is sandwiched between the magnetic gaps S in the inner portion of the Hall element 12, whereas the restriction member 42 of the second embodiment has a hole between the magnetic gaps S. It is sandwiched between the outer portions of the element 12.

As described above, in the second embodiment, since the regulating member 42 is interposed between the magnetic gaps S of the core 14 without any gap, the stress generated with the hardening of the sealing material 29 is applied to the core 14. Even so, the deformation of the magnetic gap S is suppressed by the restricting member 42, and the dimensional shape of the magnetic gap S does not change from the set value.
Therefore, also in the second embodiment, the same operation and effect as in the first embodiment can be obtained.

(Third embodiment)
FIG. 7 is an exploded perspective view of an essential part for explaining a schematic configuration of the current sensor 50 according to the third embodiment.
FIG. 8 is a perspective view of the current sensor 50.
FIG. 9 is a plan view of the main part of the current sensor 50.

The third embodiment differs from the current sensor 10 of the first embodiment only in that the regulating member 28 of the first embodiment is omitted and a regulating member 52 is provided instead.
That is, the current sensor 50 includes the Hall element 12, the core 14 (core piece 15, magnetic gap S), the housing 16 (accommodating portion 17, connector mounting portion 18, circuit accommodating portion 19, core accommodating portion 20, insertion hole 25, outer periphery. Wall 26), electronic component 21, wiring members 22 to 24, mounting bracket 27, sealing material 29, regulating member 52, and the like.

  On the bottom surface 19 a of the circuit housing portion 19, a circular-shaped regulating member 52 having a through hole formed in the central portion is erected. The hall element 12 is fitted in the through hole of the regulating member 52, and the regulating member 52 surrounds the hall element 12. And when the core 14 is accommodated in the accommodating part 17, the arrangement | positioning location and dimension shape of the regulating member 52 are set so that it may be pinched | interposed between the magnetic gaps S of the core 14 without a clearance gap. The regulating member 52 is made of a non-magnetic synthetic resin material and is integrally formed with the housing 16 by injection molding.

  As described above, in the third embodiment, since the regulating member 52 is sandwiched between the magnetic gaps S of the core 14 without any gap, the stress generated as the sealing material 29 is cured is applied to the core 14. Even so, the deformation of the magnetic gap S is suppressed by the restricting member 52, and the dimensional shape of the magnetic gap S does not change from the set value.

  According to the third embodiment in which the regulating member 52 is sandwiched between the magnetic gaps S of the core 14 without any gaps, the regulating members 28 and 42 are sandwiched between a part of the magnetic gaps S of the core 14. Compared to the first embodiment and the second embodiment, the deformation of the magnetic gap S can be more reliably suppressed, so that the operation and effect of the first embodiment can be further enhanced.

[Another embodiment]
In each of the above embodiments, the regulating members 28, 42, 52 and the casing 16 are integrally formed by injection molding. However, the regulating members 28, 42, 52 formed separately from the housing 16 may be attached and fixed to the housing 16 (the bottom surface 19 a of the circuit housing portion 19).

The principal part disassembled perspective view for demonstrating schematic structure of the current sensor 10 of 1st Embodiment which actualized this invention. A perspective view of current sensor 10 of a 1st embodiment. The principal part top view of the current sensor 10 of 1st Embodiment. The principal part disassembled perspective view for demonstrating schematic structure of the current sensor 40 of 2nd Embodiment which actualized this invention. The perspective view of the current sensor 40 of 2nd Embodiment. The principal part top view of the current sensor 40 of 2nd Embodiment. The principal part disassembled perspective view for demonstrating schematic structure of the current sensor 50 of 3rd Embodiment which actualized this invention. The perspective view of the current sensor 50 of 3rd Embodiment. The principal part top view of the current sensor 50 of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 40, 50 ... Current sensor 12 ... Hall element 14 ... Core 15 ... Core fragment 16 ... Housing 17 ... Housing part 19 ... Circuit accommodating part 20 ... Core accommodating part 28, 42, 52 ... Restriction member 29 ... Sealing material S ... Magnetic gap

Claims (4)

A ring-shaped core in which a plurality of thin-plate core pieces are laminated and integrated;
A magnetic gap formed in a part of the core;
Hall elements arranged between the magnetic gaps,
A housing having an accommodating portion for accommodating the core and the Hall element;
A current sensor comprising a sealing material filled in the housing of the housing and sealing the core and the Hall element,
The current sensor according to claim 1, wherein a deformation preventing means for preventing deformation of the magnetic gap is provided in the housing portion of the housing. The current sensor according to claim 1.
The magnetic gap comprises a cut portion of the core;
The deformation sensor includes a regulating member that is sandwiched between the magnetic gaps without a gap when the core is housed in the housing of the housing. The current sensor according to claim 2,
The current sensor according to claim 1, wherein the regulating member is sandwiched between at least one of the inside and the outside of the magnetic gap. The current sensor according to claim 2,
The current sensor according to claim 1, wherein the restricting member surrounds the hall element and is sandwiched between the magnetic gaps.

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