JPH0754331B2 - Current detection unit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a current detection unit that detects a leakage of magnetic flux generated by a current flowing in a coil by a magnetic sensor.

[Conventional technology]

An example of a conventional current detection unit is shown in FIG. This is a coil unit 53 formed by winding a copper wire coil 52 around a core 51 of a ring-shaped magnetic material, and arranging a magnetic sensor 55 in a slit 54 that is formed by cutting a part of the core 51.
A magnetic field is generated in the core 51 by the current flowing through the core 52,
The intensity of the magnetic field of the magnetic flux leaked from the slit end face of 51 is detected by the magnetic sensor 55 to measure the amount of current flowing through the coil 52.

Further, FIG. 6 shows another conventional example. This forms a substantially annular core 56 with a rod-shaped magnetic body 56a and curved linear magnetic bodies 56b on both sides thereof, and a copper wire coil 57 is wound around the rod-shaped magnetic body 56a to form a coil unit 58, which is then curved. Both ends of the linear magnetic body 56b are opposed to the surface of the magnetic sensor 59, and the amount of current flowing through the coil 57 by detecting the magnetic field strength at the end surface of the linear magnetic body 56b by the magnetic sensor 59. Is to measure.

[Problems to be Solved by the Invention]

However, in a conventional current detection unit, one coil and one magnetic sensor are paired, so in a system that detects current in multiple systems, a plurality of current detection units (a plurality of coils and a plurality of coils) are used. Magnetic sensor). Therefore, in the multi-current system, there is a problem that the number of components is increased and the area occupied by the current detection unit on the substrate is increased.

In addition, even in a system that detects one current, one coil is used for one magnetic sensor, so a relatively large coil must be mounted on the board, and the coil must be attached to the gap between other parts. However, it was difficult to dispose the current detection units on the substrate.

Furthermore, in the conventional current detection unit, since the closed magnetic circuit coil wound around the ring-shaped or substantially ring-shaped core is used, the outer shape becomes large due to the central space (hole of the core) of the coil, This is an obstacle to downsizing the current detection unit. Further, the closed magnetic circuit coil has a structure in which winding work of the coil is difficult to perform, which causes a problem of high manufacturing cost.

The present invention has been made in view of the above technical background, and an object thereof is to make it possible to reduce the mounting area on a substrate with a small size, and also to easily perform layout design of coils,
Another object of the present invention is to provide an inexpensive current detection unit having a simple structure.

[Means for Solving the Problems]

Therefore, in the current detection unit of the present invention, one or a plurality of open magnetic path coils are mounted close to each other on the front surface and the back surface of the substrate, and the magnetic flux leaked from these coils passes through the magnetic sensor. The feature is that a magnetic sensor is arranged between them.

[Action]

In the present invention, a plurality of coils are arranged for one magnetic sensor, and the magnetic flux of each coil passes through the magnetic sensor. Therefore, in a system that detects a plurality of currents, each coil has a coil. If different currents are passed, the magnetic sensor can be shared. In other words, if different currents flow through each coil, when a current flows through one of the coils, the magnetic flux generated in that coil is detected by the magnetic sensor, and one magnetic sensor can detect multiple currents. Will be possible. Therefore, the number of parts can be reduced, the cost of parts can be reduced, the size of the current detection unit can be reduced, and the mounting area on the substrate or the like can be reduced.

In the case of a system that detects one current, the same current is applied to each coil, and the current is applied in the direction in which the magnetic fields of the coils strengthen at the position of the magnetic sensor. Therefore, if the same sensitivity is obtained, each coil can be made smaller than the case where only one coil is used as in the conventional example, and this plurality of small coils can be distributed and arranged on the substrate or the like. Further, the layout design of the current detection unit on the substrate or the like becomes easy, which can contribute to high-density mounting of the substrate.

Moreover, since the coils are arranged on the front surface and the back surface of the board, the parts are not biased to one surface of the board,
The current detection unit can be configured by effectively using both the front and back surfaces of the substrate, and the current detection unit can be made more compact and the degree of freedom in coil arrangement is further increased.

Further, since the open magnetic circuit coil is used, there is no useless space unlike a closed magnetic circuit coil wound around a ring-shaped core or the like, and the current detection unit can be further downsized. Also,
By using the open magnetic circuit coil, the coil winding work can be simplified, and the manufacturing cost of the current detection unit can be reduced.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 and FIG. 2 show a first embodiment of the present invention in which two chip coils 4, 4 are vertically arranged on the upper surface and the lower surface of the substrate 1, and the space between the chip coils 4, 4 is shown. Magnetic sensor 3
Is arranged.

The chip coil 4 is formed by winding a copper wire coil 2 around an outer periphery of a core 5 made of a magnetic material such as ferrite. The core 5 is provided with flanges 7 on both ends of a columnar coil winding portion 6, and the coil 2 is wound around the coil winding portion 6. Since this chip coil 4 has an open magnetic path structure, it is only necessary to wind the coil 2 around the straight coil winding portion 6 at the time of manufacturing the chip coil 4, and the winding work of the coil 2 can be performed easily, and the manufacturing cost can be reduced. Can be cheaper. Further, the size can be reduced as compared with a coil unit having a closed magnetic circuit structure such as a ring. Since the chip coil 4 is surface-mounted on the substrate 1 such as a printed wiring board, the flange 7 is provided with two electrodes (not shown), and both ends of the coil 2 are electrically connected to these electrodes. It is connected to the.

The magnetic sensor 3 uses a magnetoelectric conversion element such as a Hall element or a magnetoresistive element, and a lead terminal 9 extends from the magnetic sensing section 8.

In addition, the substrate 1 that constitutes the current detection unit 10 is
A sensor housing hole 11 for housing the magnetic sensor 3 is opened in a part of the current detection unit which is a part of a board for mounting other electronic circuits and the like. Also,
This substrate 1 is a double-sided printed wiring board, a wiring pattern (not shown) for connecting the electrodes of the chip coil 4 is provided on the upper surface of the substrate 1, and the electrode of the chip coil 4 is provided on the lower surface. And a wiring pattern (not shown) for connecting the lead terminals 9 of the magnetic sensor 3 are provided.

Then, as shown in FIG. 1, the magnetically sensitive portion 8 of the vertically oriented magnetic sensor 3 is inserted into the sensor housing hole 11 from the lower surface of the substrate 1, and the lead terminals 9 are soldered to the lower surface wiring pattern with the solder 12. I am doing it. Chip coils 4, 4 are arranged vertically above and below the sensor housing hole 11, respectively, and the chip coil 4 on the upper surface is soldered with electrodes on the upper surface wiring pattern by solder 13, and the chip coil 4 on the lower surface is soldered. The electrodes are soldered to the lower surface wiring pattern by 14. In this way, the magnetic sensor 3 is arranged between the end faces of the upper and lower chip coils 4 in the sensor housing hole 11. Since the magnetic sensor 3 is housed in the sensor housing hole 11 in this way, the magnetic sensor 3 can be positioned by the sensor housing hole 11, and the chip coils 4, 4 can be mounted at a predetermined position with high accuracy by an automatic machine or the like. Alternatively, the chip coils 4, 4 and the magnetic sensor 3 can be accurately positioned with respect to each other by the wiring pattern, and thus stable detection accuracy can be obtained.

When detecting two current systems using the current detection unit 10 assembled as described above, two coils 2, 2
The electrodes are connected so that the currents of different circuits flow to each other.
Then, when a current flows through one of the coils 2, a magnetic flux as shown in FIG.
The magnetic flux leaking from the end face of is detected by the magnetic sensor 3, and the magnetic sensor 3 measures the amount of current flowing through the coil 2 by detecting the strength of this magnetic field. In this case, the magnetic sensor 3 can detect when any current flows in any of the coils 2, so that one magnetic sensor 3 can detect two currents.
Can be shared by the two coils 2. When the magnitudes of the currents flowing through both coils are different from each other and have a substantially constant value, it is possible to determine which coil the current has flown with, or whether the current has flown through both coils.

Next, when detecting one current, two coils 2,
2 are connected in series or in parallel, for example, by the wiring pattern of the substrate 1, and current flows through both coils 2 and 2 at the same time to generate a magnetic flux. Moreover, as shown in FIG. Are connected in such a direction that the magnetic flux density passing through the magnetically sensitive portion 8 increases. Therefore, in order to obtain the same sensitivity, each coil 2,2 can be made smaller than in the case of only one coil, and these two small coils 2,2
Can be distributed on the front and back sides of the board 1 and can be placed in a gap between other parts, etc., and the parts are not biased to one surface of the board 1 and the layout design of the coils 2 and 2 can be performed. Can be done easily.

FIG. 3 shows a second embodiment of the present invention (the same parts as those in the embodiment of FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The same applies to the following embodiments). Chip coils 4 and 4 are arranged parallel to each other on the top and bottom surfaces,
One flange 7 of 4, 4 is made to face the sensor housing hole 11. The magnetic sensor 3 has a magnetic sensing part 8 as a sensor storage hole.
11 is inserted and the lead terminals are soldered to the wiring pattern. Therefore, the magnetic sensor 3 is arranged between the upper and lower flanges 7 and 7 in the sensor housing hole 11, and the magnetic flux leaking from the flange 7 passes through the magnetic sensitive section 8 in any of the chip coils 4. There is. In this arrangement, by using the two open magnetic circuit coils 2 and 2, the magnetic flux partially constitutes a closed circuit as shown by the imaginary line in FIG. Leakage can be reduced and sensitivity is improved.

FIGS. 4A and 4B show a third embodiment of the present invention, which is delivered with the magnetic sensor 3 lying sideways in the sensor housing hole 11. Magnetic sensor 3 in such an orientation
Since the dimension of the magnetic sensor 3 in the thickness direction of the substrate 1 becomes smaller when the magnetic sensor 3 is housed in the sensor storage hole 11, the magnetic sensor 3 having a height larger than the thickness of the substrate 1 also has a sensor storage hole.
The protrusion length from 11 can be reduced.

The embodiment of the present invention is not limited to the above embodiment,
Various other methods are possible. For example, in the above embodiment,
Although both use two chip coils, three or more chip coils may be used. Further, not only the chip coil containing the core but also the coil alone may be used. Further, the magnetic sensor may be arranged on the front surface or the back surface of the substrate, but if the magnetic sensor is housed in the sensor storage hole as in the above embodiment, the current detecting unit can be made compact by using the thickness of the substrate. You can

〔The invention's effect〕

According to the present invention, when used in a system that detects a plurality of currents,
The magnetic sensor can be commonly used for each coil, the component cost can be reduced by reducing the number of components, the current detection unit can be downsized, and the mounting area on the substrate or the like can be reduced. Also, if used in a system that detects one current, relatively small coils can be dispersedly arranged on a substrate, etc., and the degree of freedom of arrangement on the substrate, etc. can be increased to facilitate layout design. High-density mounting is also easy. Moreover, since the coils are arranged on the front surface and the back surface of the board, respectively, the front and back surfaces of the board can be utilized, the current detection unit can be made more compact, and the degree of freedom in arranging the coils is increased. Further, since the open magnetic circuit coil is used, there is no useless space unlike the closed magnetic circuit coil, and the current detection unit can be further downsized. Further, by using the open magnetic circuit coil, the winding work of the coil can be simplified, and the manufacturing cost of the current detection unit can be reduced.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a first embodiment of the present invention, FIG. 2 is an explanatory view showing a magnetic flux flow of the same, and FIG. 3 is a view showing a second embodiment of the present invention. Front view with part broken, No. 4
(A) and (b) are a partially cutaway front view and a partially broken side view showing a third embodiment of the present invention, FIG. 5 is a perspective view of a conventional example, and FIG. 6 is another conventional example. FIG. 1 ... Substrate, 2 ... Coil 3 ... Magnetic sensor

Claims (1)

[Claims] 1. A single or a plurality of open magnetic circuit coils are mounted close to each other on the front surface and the back surface of a substrate,
A current detecting unit, wherein a magnetic sensor is arranged between the coils so that a leakage magnetic flux emitted from these coils passes through the magnetic sensor.