JP3757145B2 - Current sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a current sensor capable of measuring a current flowing through an electric wire to be measured by inserting the electric wire to be measured through a penetrating portion of a case.
[0002]
[Prior art]
This type of current sensor is widely known in Japanese Patent Application Laid-Open No. 6-289059 and Japanese Utility Model Laid-Open No. 7-36071. 7 and 8 show examples of conventional current sensors similar to those described in those publications.
[0003]
FIG. 7 is a perspective view showing the current sensor 1 in use, and FIG. 8 is a configuration diagram of the current sensor 1. The case 2 of the current sensor 1 includes a case body 3 and a cover 4 that is vibration-welded or ultrasonically welded to the case body 3. Case 2 has penetration part 5 for inserting electric wire (in this example, bus bar) Wb which is a measuring object.
[0004]
As shown in FIG. 8C, an annular space 6 is formed inside the case 2 so as to surround the through portion 5 for passing the electric wire Wb, and the core 7 is accommodated in the space 6. Yes. The core 7 has an annular shape surrounding the penetrating portion 5 and has a magnetic gap at one place, and a hall element (magnetic sensitive element) 8 is arranged in the magnetic gap. The Hall element 8 is mounted on a circuit board 9 housed and fixed in the case 2. The circuit board 9 has a Hall element 8 and a power supply circuit for supplying a predetermined current to the Hall element 8, and a Hall element 8. A processing circuit for processing the output signal and detecting a current flowing through the electric wire Wb is mounted. 10 is a connector for connecting the circuit board 9 and an external circuit, and 11 is a terminal, which is embedded in the case body 3 in advance.
[0005]
In order to obtain the current sensor 1, the core 7 is accommodated in the case body 3, the circuit board 9 on which the Hall element 8 and the like are mounted is accommodated, the circuit board 9 and the terminal 11 are connected, and then the cover 4 The case main body 3 and the cover 4 are integrated in an airtight manner by vibration welding or ultrasonic welding. Thereby, the current sensor 1 can be obtained. In addition, the part shown with the code | symbol 12 is a welding location of the case main body 3 and the cover 4. FIG.
[0006]
When this current sensor 1 is used, the electric wire Wb is inserted through the through portion 5 of the case 2 and set, and a predetermined current is passed through the hall element 8. Then, since the magnetic flux generated based on the current flowing through the electric wire Wb passes through the magnetic gap of the core 7, a signal voltage is generated in the Hall element 8 according to the magnetic flux, and the processing circuit based on the signal voltage A current value flowing through the electric wire Wb is detected.
[0007]
[Problems to be solved by the invention]
By the way, although the penetration part 5 for letting an electric wire pass to this current sensor 1 is provided in the case 2, depending on the kind and diameter of the electric wire, a big play can be made between the penetration part 5 and the electric wire. As a result, vibration or rattling may be caused, and in some cases, the sensor may be damaged or the detection accuracy may be deteriorated due to sensor displacement. In order to prevent this, it is conceivable to prepare a large number of variations of the current sensor with different shapes and sizes of the penetrating portions, but there is a problem that the cost increases.
[0008]
In consideration of the above circumstances, the present invention can flexibly cope with differences in the types and diameters of the wires to be measured, and reduces variation by preventing extra play between the wires and the penetrations. An object of the present invention is to provide a current sensor that can reduce the cost.
[0009]
[Means for Solving the Problems]
The invention of claim 1 is a component essential for exhibiting a current measuring function in a current sensor capable of measuring a current flowing through the electric wire by inserting the electric wire to be measured through the penetrating portion of the case. And a cover that is attached and fixed so as to close the opening of the case body, and a cylindrical guide that forms the penetrating part corresponding to the electric wire to be measured is formed integrally with the cover. It is characterized by that.
[0010]
In this invention, a cylindrical guide is provided in a cover that is retrofitted to the case main body in order to close the opening of the case main body, and a through-hole for inserting the measurement target electric wire is formed in the cylindrical guide. Excessive play between the electric wire and the penetrating portion can be reliably eliminated by simply attaching a cover having a penetrating portion corresponding to the difference in shape and diameter to the case body.
[0011]
According to a second aspect of the present invention, in the current sensor according to the first aspect of the present invention, an electric wire locking band that can be tightened with respect to the electric wire inserted through the through portion is formed integrally with the cover.
[0012]
In this invention, since the wire locking band is provided integrally with the cover, the current sensor can be fixed to the wire by tightening the wire with the wire locking band.
[0013]
The invention according to claim 3 is the current sensor according to claim 1, wherein an electric wire fixture that can be fitted to the electric wire inserted into the through portion is inserted into the cover via a flexible hinge piece. It is formed integrally.
[0014]
In this invention, since the wire fixing tool is integrally provided on the cover, the current sensor can be fixed to the electric wire by fitting the wire fixing tool to the electric wire. Moreover, since the wire fixing tool is attached via a flexible hinge piece, the wire fixing tool can be prevented from getting in the way when the wire is inserted into the sensor.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
<First Embodiment>
FIG. 1 is a perspective view showing a usage state of the current sensor 20 according to the first embodiment of the present invention, FIG. 2 is a configuration diagram of the current sensor 20, (a) is a front view, (b) is a side view, (c) ) Is a sectional view taken along arrow IIc-IIc in FIG.
[0017]
The resin case 22 constituting the housing of the current sensor 20 includes a substantially annular container-shaped case body 23 and a substantially annular plate-like cover 24 that closes the upper surface opening of the case body 23. As shown in FIG. 2C, the cover 24 is fixed to the upper end edges of the inner peripheral wall 23a and the outer peripheral wall 23b of the case body 23 by means such as vibration welding or ultrasonic welding. The part shown with the code | symbol 35 in a figure is a welding location.
[0018]
Case 22 has penetration part 25 for making cable (electric wire) Wa which is a measuring object penetrate. A cylindrical guide 24a having an inner diameter corresponding to the measurement target cable Wa is integrally formed on the inner peripheral portion of the cover 24, and the penetrating portion 25 is constituted by the cylindrical guide 24a. Therefore, the inner diameter of the inner peripheral wall 23a of the case main body 23 is set to be considerably larger than the assumed outer diameter of the cable Wa, and the cylindrical guide 24a is concentrically inserted into the center hole of the case main body 23 with a marginal space. Has been.
[0019]
In the case main body 23, an annular housing space 26 is formed by an inner peripheral wall 23a, an outer peripheral wall 23b, and a bottom wall 23c. The annular housing space 26 surrounds the through portion 25 through which the cable Wa is passed. 27 is housed. The core 27 has an annular shape surrounding the penetrating portion 25 and has a magnetic gap at one location, and a hall element (magnetic sensitive element) 28 is disposed in the magnetic gap.
[0020]
The Hall element 28 is mounted on a circuit board 29 accommodated and fixed in the case main body 23, and the circuit board 29 has a power supply circuit for supplying a predetermined current to the Hall element 28 together with the Hall element 28 and an output of the Hall element 28. A processing circuit for processing a signal and detecting a current flowing through the cable Wa is mounted.
[0021]
A connector 30 for connecting a lead wire from an external circuit is provided on the surface of the case body 23 opposite to the side on which the cover 24 is attached. The connector 30 is connected to the circuit board 29 in the housing of the connector 30. A connector terminal 31 is provided.
[0022]
Here, the cylindrical guide 24a of the cover 24 of the case 22 in the present embodiment is formed in a cylindrical shape having a size corresponding to the outer diameter of the cable Wa to be measured. The shape and size can be changed according to the height. For example, when the electric wire to be inserted is a bus bar, it is desirable to form a rectangular cylinder corresponding to the cross-sectional shape of the bus bar.
[0023]
In order to obtain the current sensor 20, the core 27 is accommodated in the case body 23, and the circuit board 29 on which the Hall element 28 and the like are mounted is accommodated, and is embedded in the case body 23 in advance with the circuit board 29. Terminal 31 is connected. As a result, the main body portion 20A of the sensor incorporating the essential parts for exhibiting the current measuring function is completed.
[0024]
After that, a cover 24 having a cylindrical guide 24a corresponding to the target cable Wa is put on the main body portion 20A of the sensor. Then, the case main body 23 and the cover 24 are hermetically integrated by vibration welding or ultrasonic welding, thereby completing the current sensor 20 as a finished product.
[0025]
When using this current sensor 20, as shown in FIG. 1, the cable (electric wire) Wa to be measured is inserted through the through-hole 25 constituted by the cylindrical guide 24 a of the cover 24 and set in the Hall element 28. A predetermined current is passed. Then, since the magnetic flux generated based on the current flowing through the cable Wa passes through the magnetic gap of the core 27, a signal voltage is generated in the Hall element 28 according to the magnetic flux, and the processing circuit based on the signal voltage A current value flowing through the cable Wa is detected.
[0026]
As described above, according to the current sensor 20 of the present embodiment, the cylindrical guide 24a is provided on the cover 24 of the case 22, and the cylindrical guide 24a constitutes the through portion 25 for passing the electric wire (cable Wa). Therefore, by fixing the cover 24 having a different shape and size of the cylindrical guide 24a to the body portion 20A of the sensor assembled in advance according to the difference in the shape and diameter of the wire, the wire and the penetrating portion 25 The extra play that occurs during the operation can be surely eliminated, and vibration and rattling in the sensor mounting state can be prevented. Therefore, the positional deviation of the sensor can be eliminated without being affected by the type and size of the electric wire, and a stable and accurate output can be obtained.
[0027]
In addition, since it is possible to flexibly cope with various types of electric wires only by changing the cover 24 as required, variations in the main body portion 20A of the current sensor 20 can be reduced, and cost reduction can be achieved. it can.
[0028]
Second Embodiment
3 is a perspective view showing a usage state of the current sensor 50 according to the second embodiment of the present invention, FIG. 4 is a configuration diagram of the current sensor 50, (a) is a top view, and (b) is a front view.
[0029]
This current sensor 50 uses a cover 24 </ b> B integrally having a wire locking band 40 that can be tightened with respect to a cable Wa inserted through the through portion 25 as a cover of the case 22. Except the point which attached the electric wire latching band 40, it is the same as 1st Embodiment.
[0030]
The wire locking band 40 is a flexible resin band also called a “bundling band”, and includes a band portion 42 and a locking portion 43 that locks through the tip of the band portion 42, and is connected via a connecting piece 41. It is integrally provided at the tip of the cylindrical guide 24a.
[0031]
As shown in FIG. 3, the current sensor 50 can be securely fixed to the cable Wa by tightening the cable Wa with the electric wire locking band 40 in a state where the cable Wa is passed through the through portion 25. Therefore, rattling and vibration can be reliably prevented.
[0032]
<Third Embodiment>
5 is a perspective view showing a usage state of the current sensor 60 according to the third embodiment of the present invention, FIG. 6 is a configuration diagram of the current sensor 60, (a) is a front view, (b) is a side view, and (c). ) Is a top view.
[0033]
The current sensor 60 uses a cover 24 </ b> C integrally including a wire fixing tool 45 that can be fitted to a cable Wa inserted through the through-hole 25 as a cover of the case 22. Except the point which attached the electric wire fixing tool 45, it is the same as 1st Embodiment.
[0034]
The wire fixing tool 45 has a semi-cylindrical shape with a C-shaped cross section, and is integrally provided at the tip of the cylindrical guide 24a via a flexible hinge piece 46, and passes the cable Wa through the through portion 25. It is in a position that does not get in the way.
[0035]
As shown in FIG. 5, the current sensor 60 can be securely fixed to the cable Wa by fitting the wire fixing tool 45 to the cable Wa while the cable Wa is passed through the through portion 25. Therefore, rattling and vibration can be reliably prevented.
[0036]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the through portion for passing the electric wire is constituted by the cylindrical guide provided on the cover to be retrofitted to the case body, the cover having the cylindrical guide corresponding to the electric wire. Is attached to the main body portion of the sensor (portion on the case main body side), play between the electric wire and the penetrating portion can be eliminated, and vibration and rattling in the attached state can be prevented. Therefore, even when the measurement target electric wire is a cable or a bus bar, it is possible to obtain a stable and accurate output without being displaced. In addition, since various types of electric wires can be flexibly handled simply by changing the cover, variations in the main body of the sensor can be reduced, and costs can be reduced.
[0037]
According to the invention of claim 2, since the wire locking band is integrally provided on the cover, in addition to the effect of the invention of claim 1, the current sensor is fixed to the wire by tightening the wire with the wire locking band. The effect that it can do is acquired.
[0038]
According to the invention of claim 3, since the wire fixing tool is integrally provided on the cover, in addition to the effect of the invention of claim 1, the current sensor is fixed to the wire by fitting the wire fixing tool to the wire. The effect that it can do is acquired. Moreover, since the electric wire fixture is attached via the hinge piece, the electric wire fixture can be prevented from getting in the way when the electric wire is inserted through the sensor.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a usage state of a current sensor according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram of the current sensor according to the first embodiment of the present invention, in which (a) is a front view, (b) is a side view, and (c) is a cross-sectional view taken along the arrow IIc-IIc in FIG. is there.
FIG. 3 is a perspective view showing a usage state of a current sensor according to a second embodiment of the present invention.
4A and 4B are configuration diagrams of a current sensor according to a second embodiment of the present invention, in which FIG. 4A is a top view and FIG. 4B is a front view.
FIG. 5 is a perspective view showing a usage state of a current sensor according to a third embodiment of the present invention.
6A and 6B are configuration diagrams of a current sensor according to a third embodiment of the present invention, in which FIG. 6A is a front view, FIG. 6B is a side view, and FIG.
FIG. 7 is a perspective view showing a usage state of a conventional current sensor.
8 is a configuration diagram of the current sensor of FIG. 7, in which (a) is a front view, (b) is a side view, and (c) is a sectional view taken along the line VIIIc-VIIIc in FIG.
[Explanation of symbols]
20, 50, 60 Current sensor 20A body portion 22 case 23 case body 24 cover 24a cylindrical guide 25 penetrating portion 40 wire locking band 45 wire fixing tool 46 hinge piece

Claims (3)

In the current sensor that can measure the current flowing through the wire by inserting the wire to be measured through the penetration part of the case,
The case is composed of a case main body that accommodates components essential for performing the current measurement function, and a cover that is attached and fixed so as to close the opening of the case main body. A current sensor in which a cylindrical guide constituting the corresponding through portion is integrally formed. The current sensor according to claim 1,
A current sensor characterized in that an electric wire locking band capable of being tightened with respect to an electric wire inserted through the penetrating portion is integrally formed on the cover. The current sensor according to claim 1,
A current sensor, wherein an electric wire fixture that can be fitted to an electric wire inserted through the through-hole is integrally formed on the cover via a flexible hinge piece.

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