JP6538744B2 - Current detector - Google Patents

Description

  The present invention relates to a current detector of magnetic balance type, magnetic proportional type or the like used for measurement of current.

  Conventionally, there is known a prior art of a current sensor that eliminates an error caused by data processing of a detection signal (see Patent Document 1). In this prior art, the voltage from the magnetic field detection element such as a Hall element is converted into digital data by A / D conversion and then processed to reduce the bit error accompanying the data conversion and suppress the measurement error. . Further, heat is radiated by integrally forming the fin portion on the resin case, and an excessive temperature rise is prevented.

JP, 2009-210405, A

The above prior art focuses on the data processing error after converting the magnetic flux density to voltage in the Hall element, and also reduces the influence of heat.
However, even if the same current to be detected flows in the conductor, if variations occur in the positional relationship between the conductor and the magnetic core, variations occur in the magnetic flux density before conversion into voltage by the Hall element, so the measurement accuracy decreases. Do. In addition, even if the resin case is provided with heat radiation performance, the heat transmitted from the conductor can not be suppressed, so the temperature rise can not be suppressed so much.

  Then, this invention makes it a subject to provide a technique which can raise a measurement precision, suppress a temperature rise, and also can raise product value.

In order to solve the above-mentioned subject, the present invention adopts the following solution means.
The current detector of the present invention is one in which the restriction portion is integrated with the case main body. An insertion hole is formed inside the case body, and an accommodation portion is formed around the insertion hole. The insertion hole is a penetrating portion for inserting the conductor, and the accommodating portion is a portion for accommodating and holding the magnetic core and the current detection circuit. In addition, the inside of the housing portion is filled and sealed with a resin sealing body.

  The restriction portion is integrated with a portion constituting the wall of the housing along the insertion hole of the case main body. The restriction site applies different restrictions to the inside of the insertion hole (outside of the case body) and the inside of the accommodation portion (inside of the case body). That is, in the insertion portion, the outer surface of the case main body is brought close to the conductor in the insertion hole, and the inclination of the conductor with respect to the insertion direction is restricted. On the other hand, the restricting portion conversely separates the inner surface of the case main body from the conductor in the housing portion. As a result, the restricted portion brings the inner surface of the case main body closer to the magnetic core, and regulates the filling range (filling amount, volume) of the sealing body in the housing portion by that amount.

  Thus, the positional relationship between the conductor inserted through the insertion hole and the magnetic core accommodated in the housing portion is maintained constant, so that not only the detection (measurement) accuracy by the current detection circuit can be improved but also the case By suppressing the filling amount of the sealing body in the main body (accommodating portion), the product weight (mass) can be suppressed low. Further, even if the case body outer surface is made to be close to the conductor, the case body inner surface is separated from the conductor, so the influence of the heat transmitted from the conductor on the current detection circuit etc. inside can be reduced.

  Preferably, the restriction portion includes a plurality of plate-like pieces, and the leading edge of the plate-like piece is close to the conductor. As a result, the area in which the conductor and the case main body are in contact can be reduced, and the shape can be made less susceptible to the influence of heat from the conductor. Further, the total surface area of the case body can be secured large by the plurality of plate-like pieces, and the heat radiation effect can be enhanced.

  Further, in the housing portion, the portion constituting the wall around the magnetic core is stepped to be close to the magnetic core to regulate the filling range of the sealing body. Since the portion constituting the wall of the housing portion is close to the magnetic core in a step-like manner, the filling amount of the sealing body is reduced (restricted) over the entire periphery of the insertion hole, which can greatly contribute to product weight reduction. .

  Furthermore, when it has the installation surface which fixes a case main body to a target object, it is set as the shape which contacts a target object in the installation surface in the edge of several plate-shaped pieces. Thus, heat from the heat generating component of the current detection circuit can be prevented from staying between the installation surface and the object, and the plate-like piece can improve the heat radiation efficiency.

  According to the present invention, the measurement accuracy can be enhanced to suppress the temperature rise, and further, the total weight can be reduced to increase the product value.

It is a schematic diagram showing the composition of the current detector of one embodiment. It is a schematic diagram showing the composition of the current detector of one embodiment. It is an exploded perspective view of a current detector. It is the rear view which showed the current detector in the installation state. FIG. 5 is a horizontal sectional view of the current detector taken along the line V-V in FIG. 4. It is a horizontal sectional view of a current detector which becomes comparative example (1). It is a horizontal sectional view of the current detector used as comparative example (2). It is a perspective view which shows the shape of the bottom face of an electric current detector.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are schematic diagrams showing the configuration of the current detector 100 according to an embodiment. FIG. 1 is a perspective view showing the current detector 100 from the front side, and FIG. 2 is a perspective view showing the current detector 100 from the rear side.
The configuration of the current detector 100 will be described below.

[Case body]
The current detector 100 includes a case main body 102 made of, for example, a resin. The case main body 102 forms an external form of the current detector 100 and inserts a conductor (not shown) through which a detected current, which is its main purpose, flows, or for an object (also not shown) Play a fixed function. Also, inside the case main body 102, a magnetic core and a current detection circuit (not shown in FIGS. 1 and 2) are accommodated, and the inside is filled and sealed with a potting resin 106 (sealing body). It is done.

  The case main body 102 has a substantially annular shape as a whole, and an insertion hole 104 is formed in the central portion so as to penetrate in the thickness direction (the front-rear direction). In the standing posture shown in FIGS. 1 and 2, although the curved portion is noticeable on the upper surface of the case main body 102, the bottom surface has a shape based on a flat surface. Moreover, in addition to the part which continues in the curved shape of the upper surface on both sides, in addition to having the part of a longitudinally long plane, it has a shape where a plurality of plate pieces 102f are vertically arrayed at intervals.

  The case body 102 is provided with a pair of upper bracket 102a, bottom plate bracket 102b, lower bracket 102c, etc. for fixing to an object (such as a case of a device through which a detected current flows) as described above. ing. The upper bracket 102 a and the lower bracket 102 c are respectively positioned at the four corners outside the case body 102 with the insertion hole 104 at the center. Further, the pair of bottom plate brackets 102b on both sides extends in a wing shape from the bottom surface of the case main body 102 toward both sides.

  Among them, the upper bracket 102a and the lower bracket 102c are used when the case body 102 is fixed to the object on the back surface. The bottom plate bracket 102b is used when the case body 102 is fixed to the object at the bottom. In any case, each bracket 102a, 102b, 102c is formed with a hole through which any fastener (bolt, nut, boss or the like) can be inserted.

[Sealing body]
As shown in FIG. 1, the case body 102 is filled with potting resin 106, and the surface of the potting resin 106 occupies most of the front of the case body 102 (current detector 100). The potting resin 106 seals the magnetic substance core and the current detection circuit accommodated in the case main body 102, and blocks the entry of dust, moisture, and the like. A connector 108 is provided on the front of the current detector 100 so as to protrude.

  Around the insertion hole 104, the case main body 102 is composed of a wall plate portion 102d and a restriction portion 102e. Among them, the wall plate portion 102 d has a substantially octagonal peripheral wall on the front side of the case main body 102. One of the restricting portions 102e is composed of a plurality of plate-like pieces arranged in the circumferential direction on the back side of the case main body 102, and in the wall plate portion 102d, the insertion hole 104 has a smooth peripheral wall surface. In the restriction portion 102e, the insertion hole 104 has an uneven peripheral wall surface.

[Magnetic core]
FIG. 3 is an exploded perspective view of the current detector 100. FIG. As described above, the current detector 100 includes the magnetic core 110 and the current detection circuit, which are accommodated in the case main body 102. For this reason, the housing portion 102g is formed in a recessed shape from the front side to the back side in the case main body 102, and further, the housing portion 102g has an annular shape around the insertion hole 104 as a whole. The magnetic core 110 is housed in the housing portion 102 g so as to surround the insertion hole 104. In the present embodiment, the magnetic core 110 is of a type having a secondary winding 110c, and most of the outer shape shown in FIG. 3 is occupied by the secondary winding 110c. The magnetic core 110 has a ring core (for example, toroidal ring: not visible in FIG. 3) made of a magnetic material inside the secondary winding 110c, and an air gap is formed in part of the ring core. A hall element (not shown) is disposed in the air gap via the spacer 110a.

[Current detection circuit]
Further, the current detector 100 has a base plate 112 and a circuit board 114, and the base plate 112 and the circuit board 114 are also housed in the housing portion 102 g of the case main body 102 together with the magnetic core 110. A current detection circuit is formed on the circuit board 114 by mounting various electronic components together with the connector 108 and the hall element.

  An opening 112a is formed in the center of the base plate 112, and the wall plate portion 102d around the insertion hole 104 can be received in the opening 112a. Also, the circuit board 114 has a notch (no reference numeral) aligned with the opening 112 a of the base plate 112. The base plate 112 is located between the magnetic core 110 and the circuit board 114 in the housing portion 102g, and the magnetic core 110 and the circuit board 114 are attached to the base plate 112 from both sides. Then, the base plate 112 is fixed to the case main body 102, whereby the magnetic core 110 and the circuit board 114 are positioned in the housing portion 102g via the base plate 112. Although the illustration of the potting resin 106 is omitted in FIG. 3, the potting resin 106 is filled in the remaining space in a state where the magnetic core 110, the base plate 112 and the circuit board 114 are all housed in the housing portion 102g. It has become.

Installation form
FIG. 4 is a rear view showing the current detector 100 in an installed state. As described above, the current detector 100 can be installed on the bottom surface of the case main body 102 with respect to the casing S of the object through which the current to be detected flows (generates the current). In this case, the bottom surface of the case main body 102 is an installation surface, and the case main body 102 can be fixed to the housing S via the pair of bottom plate brackets 102 b on both sides.

〔conductor〕
As conductors through which the current to be detected flows, there are flat bus bars Bh and Bv and round bar bus bars Br, which are shown by two-dot chain lines in FIG. The bus bar Bh can be inserted horizontally into the insertion hole 104, the bus bar Bv can be inserted vertically, or the bus bar Br can be inserted through the entire opening.

  As shown in FIG. 4, when the bus bar Bh is inserted horizontally into the insertion hole 104, both side end surfaces (small end surfaces) are in contact with the left and right restricting portions 102e, and the bus bar Bh is vertically formed. When it is inserted, the upper and lower end surfaces (small end surfaces) are in contact with the upper and lower regulating portions 102e. When the round bar-shaped bus bar Br is inserted into the insertion hole 104, the outer peripheral surface of the bus bar Br is in contact with the restriction portions 102e at four positions which are just the octagonal oblique side.

[Regulatory site]
FIG. 5 is a horizontal sectional view of the current detector 100 taken along the line V-V in FIG. Here, although holding of the positional relationship between the bus bar Bh and the magnetic core 110 is described by taking the horizontal cross section as an example, the same holds true for the vertical cross section and the cross section at an angle of 45 °. In FIG. 5 and the subsequent figures, the base plate 112 and the circuit board 114 are not shown.

[In the insertion hole (case body outer side)]
As described above, the case main body 102 is configured of the wall plate portion 102 d and the restricting portion 102 e around the insertion hole 104, and the bus bar Bh inserted into the insertion hole 104 is the current detector 100 (case main body 102). 5 is in contact with the wall plate portion 102d on the front side (upper direction in FIG. 5), and is in contact with the restriction portion 102e on the back side. At this time, the inclination of the bus bar Bh with respect to the insertion direction is restricted because the wall plate portion 102d and the restriction portion 102e are connected in series as seen in the insertion direction and are in contact with the side surface of the bus bar Bh. Thus, the positional relationship between the bus bar Bh and the magnetic core 110 is held constant.

[Electrical characteristics]
The magnetic core 110 has the ring core 110a and the secondary winding 110b made of a magnetic material as described above, but the electric characteristics (ring core 110a particularly when the distances CL and CR from the bus bar Bh to the ring core 110a vary. The magnetic flux density (converging flux density) fluctuates, and the current detection value using the Hall element also fluctuates.
In this respect, in the present embodiment, positional deviation of the bus bar Bh can be prevented by the wall plate portion 102d and the restricting portion 102e, and the positional relationship (distances CL and CR) between the bus bar Bh and the ring core 110a can be held constant. Therefore, the measurement accuracy of the current detector 100 can be improved.

[Inside housing (case body inside)]
On the other hand, focusing attention on the inside of the case main body 102, the restriction 102e separates the inner surface of the case main body 102 from the bus bar Bh. This is because the restricting portion 102e is in the form of a plate-like piece, the inner surface of the case main body 102 is inevitably separated from the bus bar Bh in order for the tip end edge to be flush with the wall plate portion 102d. This is because it is necessary to secure a distance for extending in a plate shape to some extent. Then, the restriction portion 102e separates the inner surface of the case main body 102 from the bus bar Bh means that the inner surface of the case main body 102 is closer to the magnetic core 110 than the wall plate portion 102d in the housing portion 102g. The inner surface (portion constituting the wall) of the case body 102 is offset in a stepped manner by the proximity distance F. As a result, the filling range (the space and volume to be filled) of the potting resin 106 is restricted (reduced) between the inner surface of the case body 102 and the magnetic core 110 in the housing portion 102g, and the potting resin 106 is filled as a whole. The amount will be reduced.

  The control of the filling range of the potting resin 106 (the suppression of the filling amount) by the restricting portion 102 e as described above becomes clearer in comparison with the following comparative example.

[Comparative example (1)]
FIG. 6 is a horizontal cross-sectional view of the current detector 1000 according to comparative example (1). The current detector 1000 of the comparative example (1) does not have the restricting portion 102e which the current detector 100 of the present embodiment has, and the insertion hole 104 is entirely constituted by the wall plate portion 1002d.

  According to the comparative example (1), since the wall plate portion 1002d is in contact with the bus bar Bh throughout the inside of the insertion hole 104, the positional deviation of the bus bar Bh with respect to the insertion direction can be prevented. It can be said that it is equal. However, in such a configuration, only the wall plate portion 1002d is brought close to the bus bar Bh in the insertion hole 104, so that the wall plate portion 1002d is largely separated from the magnetic core 110 in the housing portion 102g. Thus, the filling range of the potting resin 106 is expanded between the magnetic core 110 and the magnetic core 110.

[Effect by filling range regulation]
When the present embodiment and the comparative example (1) are compared, the difference in the filling amount of the potting resin 106 in the case main body 102 (in the housing portion 102g) is clear. That is, it is understood that the filling amount (total amount) of the potting resin 106 is smaller in this embodiment than in the comparative example (1), and the material cost and the product mass can be reduced accordingly (cost reduction and weight reduction). Assuming that the size of the inserted bus bar Bh and the diameter of the magnetic core 110 (depending on the size of the current to be detected and the size of the magnetic field generated thereby) are equivalent to each other, the insertion hole 104 and the housing portion 102g are naturally Since the size of the case main body 102 and the wall thickness of the wall plate portions 102d and 1002d forming the same become equal, the shape of the present embodiment is surely provided for the filling amount of the potting resin 106 used in the comparative example (1). The filling amount can be reduced.

  Then, what happens if the filling amount of the potting resin 106 is simply reduced even in the comparative example (1)? About this point, it becomes clear by the following comparative example (2).

[Comparative example (2)]
FIG. 7 is a horizontal cross-sectional view of a current detector 1000 according to comparative example (2). Although the current detector 1000 of the comparative example (2) does not have the regulation part 102e which the current detector 100 of this embodiment has, the insertion hole 104 is offset in a stepped shape from the front side to the back side. It is comprised by the wall plate part 1002d.

  In the case of the comparative example (2), it can be said that the filling amount of the potting resin 106 is suppressed as compared with the comparative example (1) because the wall plate portion 1002d is offset. However, since the wall plate portion 1002d is simply offset, the positional deviation of the bus bar Bh can not be restricted throughout the insertion hole 104. For this reason, the distances CL 'and CR' with respect to the ring core 110a are not stabilized due to the inclination of the bus bar Bh, and the electrical characteristics are unstable, and the measurement accuracy is also unstable.

  In the current detector 100 according to the present embodiment, the restricting portion 102e functions not only on one surface but functions on both the inside and the outside of the case body 102 (in the insertion hole 104 and in the housing portion 102g). Thus, both the improvement of the measurement accuracy by the stabilization of the electrical characteristics and the reduction of the product weight (total mass) are achieved at one time. In addition, in the regulating portion 102e, the outer surface of the case body 102 makes linear contact with the bus bar Bh (contact at the leading edge of the plate-like piece). It is also advantageous in that it is hard to be

[Installation side]
The superiority according to the present embodiment is not limited to the above.
FIG. 8 is a perspective view showing the shape of the bottom surface 102 h of the current detector 100. As described above, the current detector 100 may be attached to the housing S of the object with the bottom surface 102 h as the installation surface. In this case, the bottom surface 102h of the current detector 100 (case body 102) is closed by the case S of the object, and it can not be said that it is open to the outside air. Therefore, in general, the heat generated from the mounted components (transistors and the like) of the circuit board 114 is easily accumulated between the bottom surface 102 h of the case main body 102 and the housing S.

  The inventor of the present invention pays attention to the above-mentioned point, and by setting the edges of the plurality of plate-like pieces 102 n to be in contact with the housing S on the bottom surface 102 h of the case main body 102, the space between the bottom surface 102 h and the housing S To prevent heat build up. Specifically, a plurality of plate-like pieces 102n extending in the width direction are arranged in a state in which the edge (edge) is erected with respect to the bottom surface 102h in a region near the bottom of the circuit board 114 in the bottom surface 102h. By making the outer surface of the case main body 102 concave between the pieces 102 n, each plate-like piece 102 n has a sufficient length (depth in the vertical direction). In the bottom surface 102h, the region far from immediately below the circuit board 114 is a flat portion 102m, thereby enhancing the stability at the time of installation.

  As a result, the contact area of the bottom surface 102h of the case main body 102 with the housing S is kept small as a whole, and heat is prevented from staying. In particular, when the electronic component of the circuit board 114 is a heat generation source, heat tends to build up in a region near immediately below it, but the heat retention suppressing effect is large by configuring this region with a plurality of plate pieces 102 n. Further, since the plurality of plate-like pieces 102n have a certain length, the heat dissipation area from the case body 102 is enlarged by that amount, and the heat dissipation is enhanced.

  The present invention is not limited to the above-described embodiment, and can be variously modified and implemented. In one embodiment, the insertion holes 104 have a substantially octagonal shape in accordance with the bus bars Bh and Bv to be inserted, but the insertion holes 104 may have a square shape, a hexagonal shape, a circular shape, or the like.

  The number of plate-like pieces arranged in the insertion hole 104 as the restricting portion 102e can be appropriately changed, and the setting of the offset amount (proximity distance F) to be close to the magnetic core 110 in the housing portion 102g is also appropriately It can be changed to

  Besides, the current detector 100 described with the illustration and the structure of a part thereof are merely preferable examples, and the present invention can be preferably implemented even if various elements are added to or a part of the basic structure is added. It goes without saying that

100 current detector 102 case body 102 d wall plate portion 102 e restricting portion 104 insertion hole 106 potting resin 110 magnetic core

Claims (3)

A case main body in which an insertion hole through which a conductor of the current to be detected is inserted is formed inside, and a housing portion for housing a current detection circuit together with an annular magnetic core is formed around the insertion hole;
A sealing body for filling and sealing the inside of the housing portion in a state in which the magnetic core and the current detection circuit are housed;
It is integrated with the part which constitutes the wall of the accommodation section along the insertion hole of the case main body, and in the insertion hole, the outer surface of the case main body is made close to the conductor to restrict the inclination of the conductor with respect to the insertion direction. On the other hand, the housing portion is provided with a regulation portion for regulating the filling range of the sealing body by separating the inner surface of the case main body from the conductor and bringing the inner surface of the case main body into proximity to the magnetic core .
The regulation site is
A current detector comprising a plurality of plate-like pieces extending toward the inside of the insertion hole and having a leading edge close to the conductor at a portion constituting the wall of the housing. In the current detector according to claim 1,
The regulation site is
The current detector is characterized in that a portion constituting the wall of the housing portion is stepped around the magnetic core in the housing portion and is close to the magnetic core. The current detector according to claim 1 or 2
The case body is
A current detector having an installation surface for fixing to an object, and in the installation surface, the case body contacts the object at edges of a plurality of plate-like pieces.